[Federal Register Volume 72, Number 103 (Wednesday, May 30, 2007)]
[Proposed Rules]
[Pages 30168-30207]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E7-9706]
Federal Register / Vol. 72, No. 103 / Wednesday, May 30, 2007 /
Proposed Rules
[[Page 30168]]
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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Part 82
[EPA-HQ-OAR-2002-0064; FRL-8316-7]
RIN 2060-AK26
Protection of Stratospheric Ozone: Listing of Substitutes for
Ozone-Depleting Substances--n-Propyl Bromide in Adhesives, Coatings,
and Aerosols
AGENCY: Environmental Protection Agency.
ACTION: Notice of Proposed Rulemaking.
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SUMMARY: Pursuant to the U.S. Environmental Protection Agency's (EPA or
``we'') Significant New Alternatives Policy (SNAP) program, this action
proposes to list n-propyl bromide (nPB) as an unacceptable substitute
for methyl chloroform, chlorofluorocarbon (CFC)-113, and
hydrochlorofluorocarbon (HCFC)-141b when used in adhesives or in
aerosol solvents because nPB in these end uses poses unacceptable risks
to human health when compared with other substitutes that are
available. In addition, EPA takes comment on alternate options that
would find nPB acceptable subject to use conditions in adhesives or in
aerosol solvents. This action also proposes to list nPB as acceptable,
subject to use conditions, as a substitute for methyl chloroform, CFC-
113, and hydrochlorofluorocarbon (HCFC)-141b in the coatings end use.
This proposal supersedes EPA's proposal of June 3, 2003 on the
acceptability of nPB as a substitute for ozone-depleting substances for
aerosols and adhesives.
DATES: Comments must be received in writing by July 30, 2007. Under the
Paperwork Reduction Act, comments on the information collection
provisions must be received by the Office of Management and Budget
(OMB) on or before June 29, 2007. Any person interested in requesting a
public hearing, must submit such request on or before June 29, 2007. If
a public hearing is requested, a separate notice will be published
announcing the date and time of the public hearing and the comment
period will be extended until 30 days after the public hearing to allow
rebuttal and supplementary information regarding any material presented
at the public hearing. Inquiries regarding a public hearing should be
directed to the contact person listed below.
ADDRESSES: Submit your comments, identified by Docket ID No. EPA-HQ-
OAR-2002-0064, by one of the following methods:
http://www.regulations.gov. Follow the on-line
instructions for submitting comments.
E-mail: [email protected].
Mail: Air and Radiation Docket, Environmental Protection
Agency, Mailcode 6102T, 1200 Pennsylvania Ave., NW., Washington DC
20460, Attention Docket ID No. EPA-HQ-OAR-2002-0064. In addition,
please mail a copy of your comments on the information collection
provisions to the Office of Information and Regulatory Affairs, Office
of Management and Budget (OMB), Attn: Desk Officer for EPA, 725 17th
St., NW., Washington, DC 20503.
Hand Delivery: EPA Docket Center, (EPA/DC) EPA West, Room
3334, 1301 Constitution Ave., NW., Washington, DC, Attention Docket ID
No. EPA-HQ-OAR-2002-0064. Such deliveries are only accepted during the
Docket's normal hours of operation, and special arrangements should be
made for deliveries of boxed information.
Instructions: Direct your comments to Docket ID No. EPA-HQ-OAR-
2002-0064. EPA's policy is that all comments received will be included
in the public docket without change and may be made available online at
http://www.regulations.gov, including any personal information
provided, unless the comment includes information claimed to be
Confidential Business Information (CBI) or other information whose
disclosure is restricted by statute. Do not submit information that you
consider to be CBI or otherwise protected through www.regulations.gov
or e-mail. The http://www.regulations.gov Web site is an ``anonymous
access'' system, which means EPA will not know your identity or contact
information unless you provide it in the body of your comment. If you
send an e-mail comment directly to EPA without going through http://www.regulations.gov, your e-mail address will be automatically captured
and included as part of the comment that is placed in the public docket
and made available on the Internet. If you submit an electronic
comment, EPA recommends that you include your name and other contact
information in the body of your comment and with any disk or CD-ROM you
submit. If EPA cannot read your comment due to technical difficulties
and cannot contact you for clarification, EPA may not be able to
consider your comment. Electronic files should avoid the use of special
characters, any form of encryption, and be free of any defects or
viruses. For additional instructions on submitting comments, go to
Section I.B. of the SUPPLEMENTARY INFORMATION section of this document.
Docket: All documents in the docket are listed in the http://www.regulations.gov index. Although listed in the index, some
information is not publicly available, i.e., CBI or other information
whose disclosure is restricted by statute. Certain other material, such
as copyrighted material, is not placed on the Internet and will be
publicly available only in hard copy form. Publicly available docket
materials are available either electronically in http://www.regulations.gov or in hard copy at the Air and Radiation Docket,
EPA/DC, EPA West, Room 3334, 1301 Constitution Ave., NW., Washington,
DC. The Public Reading Room is open from 8:30 a.m. to 4:30 p.m., Monday
through Friday, excluding legal holidays. The telephone number for the
Public Reading Room is (202) 566-1744, and the telephone number for the
Air and Radiation Docket is (202) 566-1742.
FOR FURTHER INFORMATION CONTACT: Margaret Sheppard, Stratospheric
Protection Division, Office of Atmospheric Programs, Mail Code 6205J,
Environmental Protection Agency, 1200 Pennsylvania Ave., NW.,
Washington, DC 20460; telephone number (202) 343-9163; fax number (202)
343-2362 e-mail address: [email protected]. Notices and
rulemakings under the SNAP program are available on EPA's Stratospheric
Ozone World Wide Web site at http://www.epa.gov/ozone/snap/regs.
SUPPLEMENTARY INFORMATION:
Table of Contents
I. General Information
A. Does this action apply to me?
B. What should I consider as I prepare my comments for EPA?
C. What acronyms and abbreviations are used in the preamble?
II. How does the Significant New Alternatives Policy (SNAP) program
work?
A. What are the statutory requirements and authority for the
SNAP program?
B. How do the regulations for the SNAP program work?
C. Where can I get additional information about the SNAP
program?
III. What is EPA proposing today?
A. What is n-propyl bromide?
B. What industrial end uses are included in our proposed
decision?
C. What is the proposed text for EPA's listing decisions?
D. What does an unacceptability determination on adhesives and
aerosols mean?
E. What is the scope of the proposed determination for coatings?
[[Page 30169]]
IV. What criteria did EPA consider in preparing this proposal?
A. Availability of Alternatives to Ozone-Depleting Substances
B. Impacts on the Atmosphere and Local Air Quality
C. Ecosystem and Other Environmental Impacts
D. Flammability and Fire Safety
E. Health impacts and exposure
V. How did EPA assess impacts on human health?
A. Newly Available Exposure Data
B. Newly Available Data on Health Effects
C. Evaluation of Acceptable Exposure Levels for the Workplace
D. Other Analyses of nPB Toxicity
E. Community Exposure Guideline
VI. What listing is EPA proposing for each end use, and why?
A. Aerosol Solvents
B. Adhesives
C. Coatings
VII. What other regulatory options did EPA consider?
A. Alternative Option for Comment: Acceptable With Use
Conditions Requiring Exposure Limit and Monitoring
B. Regulatory Options Where nPB Would Be Acceptable With Use
Conditions Requiring Specific Equipment
VIII. What are the anticipated costs of this regulation to the
regulated community?
IX. How do the decisions for EPA's June 2003 proposal compare to
those for this proposal?
X. How can I use nPB as safely as possible?
XI. Statutory and Executive Order Reviews
A. Executive Order 12866: Regulatory Planning and Review
B. Paperwork Reduction Act
C. Regulatory Flexibility Act
D. Unfunded Mandates Reform Act
E. Executive Order 13132: Federalism
F. Executive Order 13175: Consultation and Coordination With
Indian Tribal Governments
G. Executive Order 13045: Protection of Children From
Environmental Health and Safety Risks
H. Executive Order 13211: Actions That Significantly Affect
Energy Supply, Distribution, or Use
I. National Technology Transfer and Advancement Act
XII. References
I. General Information
A. Does this action apply to me?
This proposed rule would regulate the use of n-propyl bromide as an
aerosol solvent and as a carrier solvent in adhesives and coatings.
Businesses in these end uses that currently might be using nPB, or
might want to use it in the future, include:
Businesses that manufacture electronics or computer
equipment.
Businesses that require a high level of cleanliness in
removing oil, grease, or wax, such as for aerospace applications or for
manufacture of optical equipment.
Foam fabricators that glue pieces of polyurethane foam
together or foam cushion manufacturers that glue fabric around a
cushion.
Furniture manufacturers that use adhesive to attach wood
parts to floors, tables and counter tops.
A company that manufactures ammunition for the U.S.
Department of Defense. Regulated entities may include:
Table 1.--Potentially Regulated Entities, by North American Industrial Classification System (NAICS) Code or
Subsector
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NAICS code or
Category subsector Description of regulated entities
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Industry...................................... 331 Primary Metal Manufacturing.
Industry...................................... 332 Fabricated Metal Product Manufacturing.
Industry/Military............................. 332992 Small Arms Ammunition Manufacturing.
Industry...................................... 333 Machinery Manufacturing.
Industry...................................... 334 Computer and Electronic Product Manufacturing.
Industry...................................... 335 Equipment Appliance, and Component
Manufacturing.
Industry...................................... 336 Transportation Equipment Manufacturing.
Industry...................................... 337 Furniture and Related Product Manufacturing.
Industry...................................... 339 Miscellaneous Manufacturing.
Industry...................................... 326150 Urethane and Other Foam Product (except
Polystyrene) Manufacturing.
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This table is not intended to be exhaustive, but rather a guide
regarding entities likely to be regulated by this action. If you have
any questions about whether this action applies to a particular entity,
consult the person listed in the preceding section, FOR FURTHER
INFORMATION CONTACT.
B. What should I consider as I prepare my comments for EPA?
1. Submitting Confidential Business Information (CBI). Do not
submit this information to EPA through www.regulations.gov or e-mail.
Clearly mark the part or all of the information that you claim to be
CBI. For CBI information in a disk or CD ROM that you mail to EPA, mark
the outside of the disk or CD ROM as CBI and then identify
electronically within the disk or CD ROM the specific information that
is claimed as CBI. In addition to one complete version of the comment
that includes information claimed as CBI, a copy of the comment that
does not contain the information claimed as CBI must be submitted for
inclusion in the public docket. Information so marked will not be
disclosed except in accordance with procedures set forth in 40 CFR part
2.
2. Tips for Preparing Your Comments. When submitting comments,
remember to:
Identify the rulemaking by docket number and other
identifying information (subject heading, Federal Register (FR) date
and page number).
Follow directions--The agency may ask you to respond to
specific questions or organize comments by referencing a Code of
Federal Regulations (CFR) part or section number.
Explain why you agree or disagree; suggest alternatives
and substitute language for your requested changes.
Describe any assumptions and provide any technical
information and/or data that you used.
If you estimate potential costs or burdens, explain how
you arrived at your estimate in sufficient detail to allow for it to be
reproduced.
Provide specific examples to illustrate your concerns, and
suggest alternatives.
Explain your views as clearly as possible, avoiding the
use of profanity or personal threats.
Make sure to submit your comments by the comment period
deadline identified.
C. What acronyms and abbreviations are used in the preamble?
Below is a list of acronyms and abbreviations used in this
document.
8-hr--eight hour
ACGIH--American Conference of Governmental Industrial Hygienists
AEL--acceptable exposure limit
[[Page 30170]]
ASTM--American Society for Testing and Materials
BMD--benchmark dose
BMDL--benchmark dose lowerbound, the lower 95%-confidence level
bound on the dose/exposure associated with the benchmark response
BSOC--Brominated Solvents Consortium
CAA--Clean Air Act
CAS Reg. No--Chemical Abstracts Service Registry Identification
Number
CBI--Confidential Business Information
CEG--community exposure guideline
CERHR--Center for the Evaluation of Risks to Human Reproduction
CFC-113--the ozone-depleting chemical 1,1,2-trifluoro-1,2,2-
trichloroethane, C2Cl3F3, CAS Reg.
No. 76-13-1
CFC--chlorofluorocarbon
cfm--cubic feet per minute
CFR--Code of Federal Regulations
CNS--central nervous system
DNA--deoxyribonucleic acid
EDSTAC--The Endocrine Disruptor Screening and Testing Advisory
Committee
EPA--the United States Environmental Protection Agency
FR--Federal Register
GWP--global warming potential
HCFC-141b--the ozone-depleting chemical 1,1-dichloro-1-fluoroethane,
CAS Reg. No. 1717-00-6
HCFC-225ca/cb--the commercial mixture of the two ozone-depleting
chemicals 3,3-dichloro-1,1,1,2,2-pentafluoropropane, CAS Reg. No.
422-56-0 and 1,3-dichloro-1,1,2,2,3-pentafluoropropane, CAS Reg. No.
507-55-1
HCFC--hydrochlorofluorocarbon
HEC--human equivalent concentration
HFC-245fa--the chemical 1,1,3,3,3-pentafluoropropane, CAS Reg. No.
460-73-1
HFC-365mfc--the chemical 1,1,1,3,3-pentafluorobutane, CAS Reg. No.
405-58-6
HFC-4310mee--the chemical 1,1,1,2,3,4,4,5,5,5-decafluoropentane, CAS
Reg. No. 138495-42-8
HFC--hydrofluorocarbon
HFE--hydrofluoroether
HHE--health hazard evaluation
ICF--ICF Consulting
ICR--Information Collection Request
iPB--isopropyl bromide, C3H7Br, CAS Reg. No.
75-26-3, an isomer of n-propyl bromide; also called 2-bromopropane
or 2-BP
Koc--organic carbon partition coefficient, for
determining the tendency of a chemical to bind to organic carbon in
soil
LC50--the concentration at which 50% of test animals die
LOAEL--Lowest Observed Adverse Effect Level
Log Kow--logarithm of the octanol-water partition
coefficient, for determining the tendency of a chemical to
accumulate in lipids or fats instead of remaining dissolved in water
mg/l--milligrams per liter
MSDS--Material Safety Data Sheet
NAICS--North American Industrial Classification System
NIOSH--National Institute for Occupational Safety and Health
NOAEL--No Observed Adverse Effect Level
NOEL--No Observed Effect Level
nPB--ln-propyl bromide, C3H7Br, CAS Reg. No.
106-94-5; also called 1-bromopropane or 1-BP
NPRM--Notice of Proposed Rulemaking
NTP--National Toxicology Program
NTTAA--National Technology Transfer and Advancement Act
ODP--ozone depletion potential
ODS--ozone-depleting substance
OEHHA--Office of Environmental Health Hazard Assessment of the
California Environmental Protection Agency
OMB--U.S. Office of Management and Budget
OSHA--the United States Occupational Safety and Health
Administration
PCBTF--parachlorobenzotrifluoride, CAS Reg. No. 98-56-6
PEL--Permissible Exposure Limit ppm-parts per million
RCRA--Resource Conservation and Recovery Act
RFA--Regulatory Flexibility Act
RfC--reference concentration
SIP--state implementation plan
SNAP--Significant New Alternatives Policy
TCA--the ozone-depleting chemical 1,1,1-trichloroethane, CAS Reg.
No. 71-55-6; also called methyl chloroform, MCF, or 1,1,1
TCE--the chemical 1,1,2-trichloroethene, CAS Reg. No. 79-01-6,
C2Cl3H; also call trichloroethylene
TERA--Toxicological Excellence for Risk Assessment
TLV--Threshold Limit Value(tm)
TSCA--Toxic Substances Control Act
TWA--time-weighted average
UMRA--Unfunded Mandates Reform Act
U.S.C.--United States Code
VMSs--volatile methyl siloxanes
VOC--volatile organic compound
II. How does the Significant New Alternatives Policy (SNAP) program
work?
A. What are the statutory requirements and authority for the SNAP
program?
Section 612 of the Clean Air Act (CAA) authorizes EPA to develop a
program for evaluating alternatives to ozone-depleting substances,
referred to as the Significant New Alternatives Policy (SNAP) program.
The major provisions of section 612 are:
Rulemaking--Section 612(c) requires EPA to promulgate
rules making it unlawful to replace any class I (chlorofluorocarbon,
halon, carbon tetrachloride, methyl chloroform, and
hydrobromofluorocarbon) or class II (hydrochlorofluorocarbon) substance
with any substitute that the Administrator determines may present
adverse effects to human health or the environment where the
Administrator has identified an alternative that (1) reduces the
overall risk to human health and the environment, and (2) is currently
or potentially available.
Listing of Unacceptable/Acceptable Substitutes--Section
612(c) also requires EPA to publish a list of the substitutes
unacceptable for specific uses. We must publish a corresponding list of
acceptable alternatives for specific uses.
Petition Process--Section 612(d) grants the right to any
person to petition EPA to add a substitute to or delete a substitute
from the lists published in accordance with section 612(c). EPA has 90
days to grant or deny a petition. Where the Agency grants the petition,
we must publish the revised lists within an additional six months.
90-day Notification--Section 612(e) requires EPA to
require any person who produces a chemical substitute for a class I
substance to notify the Agency not less than 90 days before new or
existing chemicals are introduced into interstate commerce for
significant new uses as substitutes for a class I substance. The
producer must also provide the Agency with the producer's health and
safety studies on such substitutes.
Outreach--Section 612(b)(1) states that the Administrator
shall seek to maximize the use of federal research facilities and
resources to assist users of class I and II substances in identifying
and developing alternatives to the use of such substances in key
commercial applications.
Clearinghouse--Section 612(b)(4) requires the Agency to
set up a public clearinghouse of alternative chemicals, product
substitutes, and alternative manufacturing processes that are available
for products and manufacturing processes which use class I and II
substances.
B. How do the regulations for the SNAP program work?
On March 18, 1994, EPA published the original rulemaking (59 FR
13044) that described the process for administering the SNAP program
and issued the first acceptability lists for substitutes in the major
industrial use sectors. These sectors include: Refrigeration and air
conditioning; foam blowing; solvents cleaning; fire suppression and
explosion protection; sterilants; aerosols; adhesives, coatings and
inks; and tobacco expansion. These sectors comprise the principal
industrial sectors that historically consumed large volumes of ozone-
depleting substances.
Anyone who plans to market or produce a substitute for an ozone-
depleting substance (ODS) in one of the eight major industrial use
sectors must provide the Agency with health and safety studies on the
substitute at least 90 days before introducing it into
[[Page 30171]]
interstate commerce for significant new use as an alternative. This
requirement applies to the person planning to introduce the substitute
into interstate commerce, typically chemical manufacturers, but may
also include importers, formulators or end-users when they are
responsible for introducing a substitute into commerce.
The Agency has identified four possible decision categories for
substitutes: Acceptable; acceptable subject to use conditions;
acceptable subject to narrowed use limits; and unacceptable. Use
conditions and narrowed use limits are both considered ``use
restrictions'' and are explained below. Substitutes that are deemed
acceptable with no use restrictions (no use conditions or narrowed use
limits) can be used for all applications within the relevant sector
end-use. Substitutes that are acceptable subject to use restrictions
may be used only in accordance with those restrictions. It is illegal
to replace an ODS with a substitute listed as unacceptable.
After reviewing a substitute, the Agency may make a determination
that a substitute is acceptable only if certain conditions of use are
met to minimize risks to human health and the environment. We describe
such substitutes as ``acceptable subject to use conditions.'' If you
use these substitutes without meeting the associated use conditions,
you use these substitutes in an unacceptable manner and you could be
subject to enforcement for violation of section 612 of the Clean Air
Act.
For some substitutes, the Agency may permit a narrowed range of use
within a sector. For example, we may limit the use of a substitute to
certain end-uses or specific applications within an industry sector or
may require a user to demonstrate that no other acceptable end uses are
available for their specific application. We describe these substitutes
as ``acceptable subject to narrowed use limits.'' If you use a
substitute that is acceptable subject to narrowed use limits, but use
it in applications and end-uses which are not consistent with the
narrowed use limit, you are using these substitutes in an unacceptable
manner and you could be subject to enforcement for violation of section
612 of the Clean Air Act.
The Agency publishes its SNAP program decisions in the Federal
Register. For those substitutes that are deemed acceptable subject to
use restrictions (use conditions and/or narrowed use limits), or for
substitutes deemed unacceptable, we first publish these decisions as
proposals to allow the public opportunity to comment, and we publish
final decisions as final rulemakings. In contrast, we publish
substitutes that are deemed acceptable with no restrictions in
``notices of acceptability,'' rather than as proposed and final rules.
As described in the rule implementing the SNAP program (59 FR 13044),
we do not believe that rulemaking procedures are necessary to list
alternatives that are acceptable without restrictions because such
listings neither impose any sanction nor prevent anyone from using a
substitute.
Many SNAP listings include ``comments'' or ``further information.''
These statements provide additional information on substitutes that we
determine are unacceptable, acceptable subject to narrowed use limits,
or acceptable subject to use conditions. Since this additional
information is not part of the regulatory decision, these statements
are not binding for use of the substitute under the SNAP program.
However, regulatory requirements listed in this column are binding
under other programs. The further information does not necessarily
include all other legal obligations pertaining to the use of the
substitute. However, we encourage users of substitutes to apply all
statements in the ``Further Information'' column in their use of these
substitutes. In many instances, the information simply refers to sound
operating practices that have already been identified in existing
industry and/or building-code standards. Thus, many of the comments, if
adopted, would not require the affected industry to make significant
changes in existing operating practices.
C. Where can I get additional information about the SNAP program?
For copies of the comprehensive SNAP lists of substitutes or
additional information on SNAP, look at EPA's Ozone Depletion World
Wide Web site at http://www.epa.gov/ozone/snap/lists/index.html. For
more information on the Agency's process for administering the SNAP
program or criteria for evaluation of substitutes, refer to the SNAP
final rulemaking published in the Federal Register on March 18, 1994
(59 FR 13044), codified at Code of Federal Regulations at 40 CFR part
82, subpart G. You can find a complete chronology of SNAP decisions and
the appropriate Federal Register citations at http://www.epa.gov/ozone/snap/chron.html.
III. What is EPA proposing today?
In this action, EPA proposes to list n-propyl bromide (nPB) as (1)
unacceptable for use as a substitute for CFC-113,\1\ methyl chloroform
\2\ and HCFC-141b \3\ in the adhesive and aerosol solvent end uses; and
(2) acceptable subject to use conditions (limited to coatings at
facilities that, as of May 30, 2007, have provided EPA with information
demonstrating their ability to maintain acceptable workplace exposures)
as a substitute for methyl chloroform, CFC-113, and HCFC-141b in the
coatings end use. This Notice of Proposed Rulemaking (NPRM) supersedes
the NPRM published on June 3, 2003 (68 FR 33284) for aerosol solvents
and adhesives.
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\1\ CFC-113 is also referred to as Freon-113, or 1,1,2-
trifluoro-1,2,2-trichloroethane. Its CAS Reg. No. is 76-13-1.
\2\ Methyl chloroform is also referred to as 1,1,1-
trichloroethane, TCA, MCF, or 1,1,1. Its CAS Reg. No. is 71-55-6.
\3\ HCFC-141b is also referred to as 1,1-dichloro-1-
fluoroethane. Its CAS Reg. No. is 1717-00-6.
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A. What is n-propyl bromide?
n-propyl bromide (nPB), also called 1-bromopropane, is a non-
flammable organic solvent with a strong odor. Its chemical formula is
C3H7Br. Its identification number in Chemical
Abstracts Service's registry (CAS Reg. No.) is 106-94-5. nPB is used to
remove wax, oil, and grease from electronics, metal, and other
materials. It also is used as a carrier solvent in adhesives. Some
brand names of products using nPB are: Abzol[supreg], EnSolv[supreg],
and Solvon[supreg] cleaners; Pow-R-Wash[supreg] NR Contact Cleaner,
Superkleen Flux Remover 2311 and LPS NoFlash NU Electro Contact Cleaner
aerosols; and Whisper Spray and Fire Retardant Soft Seam 6460
adhesives.
B. What industrial end uses are included in our proposed decision?
This proposal addresses the use of n-propyl bromide in the aerosol
solvent end use of the aerosol sector and the adhesives and coatings
end uses in the adhesives, coatings, and inks sector as discussed
below. EPA is issuing a decision on the use of nPB in metals,
electronics, and precision cleaning in a separate final rule. EPA has
insufficient information for ruling on other end uses or sectors where
nPB might be used (e.g., inks, foam blowing, fire suppression).
1. Aerosol Solvents
We understand that nPB is being used as an aerosol solvent in:
Lubricants, coatings, or cleaning fluids for electrical or
electronic equipment;
Lubricants, coatings, or cleaning fluids for aircraft maintenance;
or
[[Page 30172]]
Spinnerrette lubricants and cleaning sprays used in the
production of synthetic fibers.
2. Adhesives
Types of adhesives covered under the SNAP program are those that
formerly used methyl chloroform, specifically, adhesives for laminates,
flexible foam, hardwood floors, tire patches, and metal to rubber
adhesives. Of these applications, nPB-based adhesives have been used
most widely in spray adhesives used in manufacture of foam cushions,
and to a lesser degree in laminate adhesives.
3. Coatings
The SNAP program regulates the use of carrier solvents in durable
coatings, including paints, varnishes, and aerospace coatings (59 FR
13118). The SNAP program currently does not regulate carrier solvents
in lubricant coatings, such as silicone coatings used on medical
equipment (59 FR 13119). Methyl chloroform has been used as a carrier
solvent in coatings, and to a much lesser degree, HCFC-141b also has
been a carrier solvent. This rule responds to a submission from a
facility that is substituting methyl chloroform with nPB as an
ammunition coating (sealant).
C. What is the proposed text for EPA's listing decisions?
In the proposed regulatory text at the end of this document, you
will find our proposed decisions for those end uses for which we have
proposed nPB as unacceptable or acceptable subject to use conditions.
The proposed conditions listed in the ``Use Conditions'' column would
be enforceable while information contained in the ``Further
Information'' column of those tables provides additional
recommendations on the safe use of nPB. Our proposed decisions for each
end use are summarized below in tables 2 through 4.
Proposed Listings
Table 2.--Aerosols Proposed Unacceptable Substitutes
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End Use Substitute Decision Further information
----------------------------------------------------------------------------------------------------------------
Aerosol solvents.................. n-propyl bromide (nPB) as Unacceptable......... EPA finds unacceptable
a substitute for CFC-113, risks to human health in
HCFC-141b, and methyl this end use compared to
chloroform. other available
alternatives. nPB, also
known as 1-bromopropane,
is Number 106-94-5 in
the CAS Registry.
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Table 3.--Adhesives, Coatings, and Inks Proposed Unacceptable Substitutes
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Enduse Substitute Decision Further information
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Adhesives......................... n-propyl bromide (nPB) as Unacceptable......... EPA finds unacceptable
a substitute for CFC-113, risks to human health in
HCFC-141b, and methyl this end use compared to
chloroform. other available
alternatives. nPB, also
known as 1-bromopropane,
is Number 106-94-5 in
the CAS Registry.
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Table 4.--Adhesives, Coatings, and Inks Substitutes That Are Proposed Acceptable Subject to Use Conditions
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End Use Substitute Decision Use conditions Further information
----------------------------------------------------------------------------------------------------------------
Coatings............ n-propyl bromide Acceptable subject Use is limited to EPA recommends the use
(nPB) as a to use conditions. coatings facilities of personal protective
substitute for that, as of May 30, equipment, including
methyl chloroform, 2007, have provided chemical goggles,
CFC-113, and HCFC- EPA information flexible laminate
141b. demonstrating their protective gloves and
ability to maintain chemical-resistant
acceptable workplace clothing.
exposures. EPA expects that all
users of nPB would
comply with any final
Permissible Exposure
Limit that the
Occupational Safety
and Health
Administration issues
in the future under 42
U.S.C. 7610(a).
nPB, also known as 1-
bromopropane, is
Number 106-94-5 in the
CAS Registry.
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Note: As of May 30, 2007, the Lake City Army Ammunition Plant is the only facility using nPB in coatings that
has provided information to EPA that meets this condition.
D. What does an unacceptability determination on adhesives and aerosols
mean?
In this action, EPA is proposing to find nPB unacceptable as a
substitute for methyl chloroform, CFC-113, and HCFC-141b for use as a
carrier solvent in adhesives and as an aerosol solvent. If this
proposal were to become final, it would be illegal to use nPB or blends
of nPB and other solvents in adhesives or in aerosol solvent
formulations as a substitute for ozone-depleting substances.
E. What is the scope of the proposed determination for coatings?
We propose to list nPB as an acceptable substitute, subject to use
conditions, for methyl chloroform, CFC-113, and HCFC-141b in coatings
for facilities that, as of May 30, 2007, have
[[Page 30173]]
provided EPA information demonstrating their ability to maintain
acceptable workplace exposures. EPA has received a petition to allow
use of nPB for the ammunition coating application at Lake City Army
Ammunition Plant. This is the only coatings application or facility for
which EPA has exposure and usage data demonstrating an ability to
maintain workplace exposure levels below even the minimum level of the
range of exposures that EPA is considering to be potentially acceptable
(i.e., 17 to 30 ppm) (see section IV.E for an evaluation of the health
risks associated with nPB). If other facilities are interested in using
nPB as a substitute for methyl chloroform, CFC-113, or HCFC-141b in
their coatings application, or if a person wishes to market nPB for
such use, then the interested party would need to make a submission
under the SNAP program.
IV. What criteria did EPA consider in preparing this proposal?
In the original rule implementing the SNAP program (March 18, 1994;
59 FR 13044, at 40 CFR 82.180(a)(7)), the Agency identified the
criteria we use in determining whether a substitute is acceptable or
unacceptable as a replacement for class I or II compounds:
(i) Atmospheric effects and related health and environmental
impacts;
[e.g., ozone depletion potential]
(ii) General population risks from ambient exposure to compounds
with direct toxicity and to increased ground-level ozone;
(iii) Ecosystem risks [e.g., bioaccumulation, impacts on surface
and groundwater];
(iv) Occupational risks;
(v) Consumer risks;
(vi) Flammability; and
(vii) Cost and availability of the substitute.
In this review, EPA considered all the criteria above. However, n-
propyl bromide is used in industrial applications such as electronics
cleaning or spray adhesives used in foam fabrication. In those consumer
products made using nPB, such as a piece of furniture or a computer,
the nPB would have evaporated long before a consumer would purchase the
item. Therefore, we believe there is no consumer exposure risk to
evaluate in the end uses we evaluated for this rule.
Section 612(c) of the Clean Air Act directs EPA to publish a list
of replacement substances (``substitutes'') for class I and class II
ozone depleting substances based on whether the Administrator
determines they are safe (when compared with other currently or
potentially available substitutes) for specific uses or are to be
prohibited for specific uses. EPA must compare the risks to human
health and the environment of a substitute to the risks associated with
other substitutes that are currently or potentially available. In
addition, EPA also considers whether the substitute for class I and
class II ODSs ``reduces the overall risk to human health and the
environment'' compared to the ODSs being replaced. Our evaluation is
based on the end use; for example, we compared nPB as a carrier solvent
in adhesives to other available or potentially available adhesive
alternatives.
Although EPA does not judge the effectiveness of an alternative for
purposes of determining whether it is acceptable, we consider
effectiveness when determining whether alternatives that pose less risk
are available in a particular application within an end use. There are
a wide variety of acceptable alternatives listed for aerosol solvents,
but not all may be appropriate for a specific application because of
differences in materials compatibility, flammability, degree of
cleanliness required, local environmental requirements, and other
factors.
EPA evaluated each of the criteria separately and then considered
overall risk to human health and the environment in comparison to other
available or potentially available alternatives. We concluded that
overall, environmental risks were not sufficient to find nPB
unacceptable in any of the evaluated end uses. However, the overall
risks to human health, and particularly the risks to worker health, are
sufficiently high in the adhesive and aerosol solvent end uses to
warrant our proposal to find nPB unacceptable.
A. Availability of Alternatives to Ozone-Depleting Substances
Other alternatives are available in each end use considered in this
proposal. Examples of other available alternatives for aerosol solvents
that have already been found acceptable or acceptable subject to use
conditions under the SNAP program include water-based formulations,
alcohols, ketones, esters, ethers, terpenes, HCFC-141b, HCFC-225ca/cb,
hydrofluoroethers (HFEs), hydrofluorocarbon (HFC)-4310mee, HFC-365mfc,
HFC-245fa, hydrocarbons, trans-1,2-dichloroethylene, methylene
chloride, trichloroethylene \4\ (TCE), perchloroethylene \5\, and
parachlorobenzotrifluoride (PCBTF). Of these, hydrocarbons, alcohols,
blends of trans-1,2-dichloroethylene and HFEs or HFCs, and HCFC-225ca/
cb are most likely to be used in the same applications as nPB. nPB is
already commercially available in aerosols. Its use is primarily for
electrical contact cleaning, with some use for benchtop cleaning
applications (Williams, 2005).
---------------------------------------------------------------------------
\4\ Also called trichlorethene or TCE,
C2Cl3H, CAS Reg. No. 79-01-6.
\5\ Also called PERC, tetrachloroethylene, or tetrachloroethene,
C2Cl4, CAS Reg. No. 127-18-4.
---------------------------------------------------------------------------
Many alternatives are also available for use in adhesives,
coatings, and inks: Water-based formulations, high solid formulations,
alcohols, ketones, esters, ethers, terpenes, HFEs, hydrocarbons, trans-
1,2-dichloroethylene, chlorinated solvents, PCBTF, and a number of
alternative technologies (e.g., powder, hot melt, thermoplastic plasma
spray, radiation-cured, moisture-cured, chemical-cured, and reactive
liquid). Of these, the alternative adhesives most likely to be used in
the same applications as nPB are water-based formulations, adhesives
with methylene chloride, and flammable adhesives with acetone (IRTA,
2000). nPB is already used in adhesives, and particularly in foam
fabrication and in constructing seating for aircraft (IRTA, 2000;
Seilheimer, 2001).
To our knowledge, nPB is potentially available as a carrier solvent
in coatings, but has not yet been commercialized, except for use by one
facility, the Lake City Army Ammunition Plant. The Lake City Army
Ammunition Plant evaluated twenty-nine carrier solvent alternatives to
methyl chloroform and determined that nPB is the only satisfactory
alternative for their application given the current process at that
facility (Harper, 2005).
B. Impacts on the Atmosphere and Local Air Quality
As discussed in the June, 2003 proposal, nPB emissions from the
continental United States are estimated to have an ozone depletion
potential (ODP) of approximately 0.013-0.018, (Wuebbles, 2002), lower
than that of the ozone depletion potential of the substances that nPB
would replace--CFC-113 (ODP = 1.0), and methyl chloroform and HCFC-141b
(ODPs = 0.12) (WMO, 2002). Some other acceptable alternatives for these
ODSs also have low ODPs. For example, HCFC-225ca/cb has an ODP of 0.02-
0.03 (WMO, 2002) and is acceptable as an aerosol solvent. There are
other acceptable solvents for aerosols, adhesives, and coatings that
essentially have no ODP--aqueous cleaners, HFEs, HFC-4310mee, HFC-
365mfc, HFC-245fa, hydrocarbons, volatile methyl siloxanes (VMSs),
methylene chloride, TCE, perchloroethylene, and PCBTF.
[[Page 30174]]
Based on this information, we do not believe the use of nPB within the
U.S., and within the end-uses reviewed in this rulemaking, poses a
significantly greater risk to the ozone layer than other available
substitutes.
Comments on the June 2003 NPRM expressed concern that other
countries, particularly those in equatorial regions, might assume that
nPB does not pose a danger to the stratospheric ozone layer if the U.S.
EPA's SNAP program finds nPB acceptable (Linnell, 2003; Steminiski,
2003). Because the ODP for nPB is higher when used in the tropics,\6\
we recognize the concerns raised by these commenters. However, EPA is
regulating use in the U.S. and cannot dictate actions taken by other
countries. We believe the more appropriate forum to address this
concern is through the Parties to the Montreal Protocol. At the most
recent Meeting of the Parties, the Parties made the following decision
with regard to n-propyl bromide, in order to ``allow Parties to
consider further steps regarding n-propyl bromide, in the light of
available alternatives'' (Decision XVIII/11):
---------------------------------------------------------------------------
\6\ nPB emissions in the tropics have an ODP of 0.071 to 0.100;
the portions of the U.S. outside the continental U.S., such as
Alaska, Hawaii, Guam, and the U.S. Virgin Islands, contain less than
1 percent of the U.S.'s businesses in industries that could use nPB.
Thus, their potential impact on the ozone layer must be
significantly less than that of the already low impact from nPB
emissions in the continental U.S. (U.S. Economic Census, 2002a
through f).
---------------------------------------------------------------------------
1. To request the Scientific Assessment Panel to update existing
information on the ozone depletion potential of n-propyl bromide,
including ozone depleting potential depending on the location of the
emissions and the season in the hemisphere at that location;
2. To request the Technology and Economic Assessment Panel to
continue its assessment of global emissions of n-propyl bromide, * * *
paying particular attention to:
(a) Obtaining more complete data on production and uses of n-propyl
bromide as well as emissions of n-propyl bromide from those sources;
(b) Providing further information on the technological and
economical availability of alternatives for the different use
categories of n-propyl bromide and information on the toxicity of and
regulations on the substitutes for n-propyl bromide;
(c) Presenting information on the ozone depletion potential of the
substances for which n-propyl bromide is used as a replacement;
3. To request that the Technology and Economic Assessment Panel
prepare a report on the assessment referred to in paragraph 1 in time
for the twenty-seventh meeting of the Open-ended Working Group for the
consideration of the Nineteenth Meeting of the Parties. (MOP 18, 2006)
The global warming potential (GWP) index is a means of quantifying
the potential integrated climate forcing of various greenhouse gases
relative to carbon dioxide. Earlier data found a direct 100-year
integrated GWP (100yr GWP) for nPB of 0.31 (Atmospheric and
Environmental Research, Inc., 1995). More recent analysis that
considers both the direct and the indirect GWP of nPB found a 100-yr
GWP of 1.57 (ICF, 2003a; ICF, 2006a). In either case, the GWP for nPB
is comparable to or below that of previously approved substitutes in
these end uses.
Use of nPB may be controlled as a volatile organic compound (VOC)
under state implementation plans (SIPs) developed to attain the
National Ambient Air Quality Standards for ground-level ozone, which is
a respiratory irritant. Users located in ozone nonattainment areas may
need to consider using a substitute for cleaning that is not a VOC or
if they choose to use a substitute that is a VOC, they may need to
control emissions in accordance with the SIP. Companies have petitioned
EPA, requesting that we exempt nPB from regulation as a VOC. However,
unless and until EPA issues a final rulemaking exempting a compound
from the definition of VOC and states change their SIPs to exclude such
a compound from regulation, that compound is still regulated as a VOC.
Other acceptable ODS-substitute solvents that are VOCs for state air
quality planning purposes include most oxygenated solvents such as
alcohols, ketones, esters, and ethers; hydrocarbons and terpenes;
trichloroethylene; trans-1,2-dichloroethylene; monochlorotoluenes; and
benzotrifluoride. Some VOC-exempt solvents that are acceptable ODS
substitutes include HFC-245fa, HCFC-225ca/cb, HFC-365mfc and HFC-
4310mee for aerosol solvents, and methylene chloride,
perchloroethylene, HFE-7100, HFE-7200, PCBTF, acetone, and methyl
acetate for aerosol solvents, adhesives, and coatings.
C. Ecosystem and Other Environmental Impacts
EPA considered the possible impacts of nPB if it were to pollute
soil or water as a waste and compared these impacts to screening
criteria developed by the Endocrine Disruptor Screening and Testing
Advisory Committee (EDSTAC, 1998) (see Table 5). Available data on the
organic carbon partition coefficient (Koc), the breakdown
processes in water and hydrolysis half-life, and the volatilization
half-life indicate that nPB is less persistent in the environment than
many solvents and would be of low to moderate concern for movement in
soil. Based on the LC50, the acute concentration at which
50% of tested animals die, nPB's toxicity to aquatic life is moderate,
being less than that for some acceptable cleaners (for example,
trichloroethylene, hexane, d-limonene, and possibly some aqueous
cleaners) and greater than that for some others (methylene chloride,
acetone, isopropyl alcohol, and some other aqueous cleaners). The
LC50 for nPB is 67 milligrams per liter (mg/l), which is
greater and thus less toxic than an LC50 of 10 mg/l, one of
EPA's criteria for listing under the Toxics Release Inventory (US EPA,
1992; ICF, 2004a). Based on its relatively low bioconcentration factor
and log Kow value (logarithm of the octanol-water partition
coefficient), nPB is not prone to bioaccumulation. Table 5 summarizes
information on environmental impacts of nPB; trans-1,2-
dichloroethylene, a commonly-used solvent in blends for aerosol
solvents, precision cleaning, and electronics cleaning; acetone, a
commonly-used carrier solvent in adhesives; trichloroethylene, a
solvent used for metals, electronics, and precision cleaning that could
potentially be used in aerosol or adhesive end-uses; and methyl
chloroform, an ODS that nPB would replace.
[[Page 30175]]
Table 5.--Ecosystem and Other Environmental Properties of nPB and Other Solvents
--------------------------------------------------------------------------------------------------------------------------------------------------------
Description of Value for trans-
Property environmental Value for nPB 1,2-dichloro- Value for acetone Value for Value for methyl
property ethylene trichloroethylene chloroform
--------------------------------------------------------------------------------------------------------------------------------------------------------
Koc, organic-carbon partition Degree to which a 330 (Source: ICF, 32 to 49 (Source: 5.4 (Source: 106 to 460 (Source: 152 (Source: U.S.
coefficient. substance tends 2004a). ATSDR, 1996). ATSDR, 1994). ATSDR, 1997). EPA, 1994a).
to stick to soil
or move in soil.
Lower values (<
300)\*\ indicate
great soil
mobility; values
of 300 to 500
indicate moderate
mobility in soil.
Break down in water............ Mechanism and Hydrolysis is Photolytic Biodegradation is Volatilization and Volatilization
speed with which significant. decomposition, most significant biodegradation most most
a compound breaks Hydrolysis half- dechlorination form of breakdown significant, with significant;
down in the life of 26 days and (Source: ATSDR, hydrolysis biodegradation
environment. (Source: ICF, biodegradation 1994). relatively and hydrolysis
(Hydrolysis half- 2004a). are significant; insignificant. also occur
life values > 25 hydrolysis not Hydrolysis half- (Source: ATSDR,
weeks\*\ are of significant life of 10.7 to 30 2004).
concern.). (Source: ATSDR, months (Source:
1996). ATSDR, 1997).
Volatilization half-life from Tendency to 3.4 hours-4.4 days 3 to 6.2 hours 7.8 to 18 hours 3.4 hours to 18 days Hours to weeks
surface waters. volatilize and (Source: ICF, (Source: ATSDR, (Source: ATSDR, (Source: ATSDR, (Source: U.S.
pass from water 2004a). 1996). 1994). 1997). EPA, 1994a).
into the air.
LC50 (96 hours) for fathead Concentration at 67 mg/L (Source: 108 mg/L (Source: 7280 to 8120 mg/L 40.7 to 66.8 mg/L 52.8 to 105 mg/L
minnows. which 50% of Geiger, 1988). U.S. EPA, 1980). (Source: Fisher (Source: NPS, 1997). (Source: U.S.
animals die from Scientific, 2001). EPA, 1994a).
toxicity after
exposure for 4
days.
log Kow........................ Logarithm of the 2.10 (Source: ICF, -0.48 (Source: -0.24 (Source: 2.38 (Source: 2.50 (Source:
octanol/water 2004a). LaGrega et al., LaGrega et al., LaGrega et al., LaGrega et al.,
partition 2001, p. 1119). 2001, p. 1117). 2001, p. 1127). 2001, p. 1127).
coefficient, a
measure of
tendency to
accumulate in
fat. Log Kow
values >3 \;*\
indicate high
tendency to
accumulate.
Bioconcentration factor........ High factors 23 (Source: HSDB, 5 to 23 (Source: <1 (Source: ATSDR, 10 to 100 (Source: <9 (Source: U.S.
(>1000)\*\ 2004). ATSDR, 1996). 1994). ATSDR, 1997). EPA, 1994a).
indicate strong
tendency for fish
to absorb the
chemical from
water into body
tissues.
--------------------------------------------------------------------------------------------------------------------------------------------------------
\*\Criteria from EDSTAC, 1998.
nPB is not currently regulated as a hazardous air pollutant and is
not listed as a hazardous waste under the Resource Conservation and
Recovery Act (RCRA). nPB is not required to be reported as part of the
Toxic Release Inventory under Title III of the Superfund Amendments and
Reauthorization Act. Despite this, large amounts of nPB might be
harmful if disposed of in water. We recommend that users dispose of nPB
as they would dispose of any spent halogenated solvent (F001 waste
under RCRA). Users should not dump nPB into water, and should dispose
of it by incineration. We conclude that nPB does not pose a
significantly greater risk to the environment than other available
alternatives, and that the use of nPB within the U.S. should not be
prohibited under the SNAP program on the basis of its environmental
impacts.
D. Flammability and Fire Safety
A number of commenters on the June 2003 proposal provided
additional information on the flammability of nPB using standard test
methods for determining flash point, such as the American Society for
Testing and Materials (ASTM) D 92 open cup, ASTM D56 Tag closed cup,
and ASTM D93 Pensky-Martens closed cup methods (BSOC, 2000; Miller,
2003; Morford, 2003a, 2003b, and 2003c;
[[Page 30176]]
Shubkin, 2003; Weiss Cohen, 2003). We agree with the commenters that by
these standard test methods, nPB displayed no flash point. Thus under
standard test conditions, nPB is not flammable, and it should not be
flammable under normal use conditions. With its low potential for
flammability, nPB is comparable to chlorinated solvents, HCFCs, HFEs,
HFC-245fa, HFC-4310mee, and aqueous cleaners, and is less flammable
than many acceptable substitutes, such as ketones, alcohols, terpenes,
and hydrocarbons. nPB exhibits lower and upper flammability limits of
approximately 3% to 8% (BSOC, 2000). A number of other solvents that
are typically considered to be non-flammable also have flammability
limits (for example, methylene chloride, HCFC-141b, and methyl
chloroform). If the concentration of vapor of such a solvent falls
between the upper and lower flammability limits, it could catch fire in
presence of a flame. Such a situation is unusual, but users should take
appropriate precautions in cases where the concentration of vapor could
fall between the flammability limits.
E. Health Impacts and Exposure
In evaluating potential human health impacts of nPB used as a
substitute for ozone-depleting substances, EPA considered impacts on
both exposed workers and on the general population. Using the same
approach finalized in the original SNAP rulemaking, EPA evaluated the
available toxicity data using EPA guidelines to develop health-based
criteria to characterize human health risks (US EPA, 1994b. Inhalation
Reference Concentration Guidelines; U.S. EPA, 1991. Guidelines for
Developmental Toxicity Risk Assessment; U.S. EPA, 1995a. Benchmark Dose
guidelines; U.S. EPA, 1996. Guidelines for Reproductive Toxicity Risk
Assessment).
To assess human health risks, EPA followed the four basic steps of
risk assessment outlined by the National Academy of Sciences: hazard
identification, dose-response relationship, exposure assessment, and
risk characterization (NAS, 1983). First, EPA examined available
studies on nPB's effects. Second, EPA considered the acceptable
exposure levels for evaluating worker exposure and a community exposure
guideline (CEG) for evaluating exposure to the general population based
upon inhalation exposure. Third, EPA compared the acceptable exposure
levels and CEG to available exposure data and projections of exposure
levels to assess exposure, including new exposure data available since
publication of the June 2003 NPRM. Finally, EPA decided whether there
was sufficient evidence indicating that nPB could be used as safely as
other alternatives available in a particular end use.
Authority To Set an Acceptable Exposure Limit
Two commenters on the June 2003 NPRM said that EPA has no
jurisdiction to develop any acceptable exposure limit (AEL) designed to
be applicable to a workplace environment and that only the Occupational
Safety and Health Administration (OSHA) has that authority (Stelljes,
2003; Morford, 2003d). In contrast, another commenter said that EPA has
the authority to set an AEL for nPB under section 612 of the Clean Air
Act, has done so in the past for other chemicals (e.g., HFC-4310mee,
HCFC-225ca/cb), and should require the AEL as a use condition (Risotto,
2003).
EPA believes it has the authority to calculate exposure limits for
the workplace under section 612. Section 612(c) specifically states
that
The Administrator shall issue regulations: providing that it shall
be unlawful to replace any class I or class II substance with any
substitute substance which the Administrator determines may present
adverse effects to human health or the environment, where the
Administrator has identified an alternative to such replacement
that--
(1) reduces the overall risk to human health and the
environment; and
(2) is currently or potentially available.
Thus, we must compare the risks to human health and the environment of
a substitute to the risks associated with other substitutes that are
currently or potentially available, as required by the Clean Air Act.
In order to compare risks to human health, EPA performs quantitative
risk assessments on different chemicals comparing exposure data and
exposure limits, following the process described above by the National
Academies of Science (NAS, 1983) and as described in the preamble to
the original final SNAP rule (March 18, 1994; 59 FR 13066). Because
most humans who are exposed to nPB are exposed in the workplace, the
appropriate exposure data and exposure limits to protect human health
must include workplace exposure data and acceptable exposure limits for
the workplace. Because there is wide disparity in acceptable exposure
limits for nPB developed by industry, ranging from 5 ppm to 100 ppm
(Albemarle, 2003; Chemtura, 2006; Docket A-2001-07, item II-D-19;
Enviro Tech International, 2006; Farr, 2003; Great Lakes Chemical
Company, 2001), and because there is not a Permissible Exposure Limit
for nPB set by the Occupational Safety and Health Administration, EPA
believes it is appropriate to independently evaluate the human health
risks associated with use of nPB in the workplace. Similarly, EPA has
developed a community exposure guideline to assess the human health
effects of nPB exposure to the general public.
Skin Notation
Several commenters on the June 2003 proposal stated that a skin
notation for nPB is appropriate, while another commenter agreed with
EPA's proposal that no skin notation was necessary (Smith, 2003; HESIS,
2003; Werner, 2003, Weiss Cohen, 2003). Rat studies indicate that
dermal exposure to nPB results in neither appreciable absorption
through the skin (RTI, 2005) nor systemic toxicity (Elf Atochem, 1995).
Unlike methyl chloride and dichlorvos, which are absorbed through the
skin and could contribute to systemic toxicity (ACGIH, 1991), EPA is
not proposing to include a skin notation for nPB in the information
provided to users associated with this rulemaking because of the
relatively low level of absorption. The American Conference of
Governmental Industrial Hygienists (ACGIH) provides no skin notation in
its documentation for threshold limit values (TLVs) for several
solvents, including nPB (ACGIH, 2005), methylene chloride, and
perchloroethylene, and there is no evidence that absorption through the
skin is greater for nPB than for the other halogenated compounds.
Further, including a statement giving advice about how to reduce skin
exposure in the ``Further Information'' column of listings is likely to
be more informative to workers than a skin notation.
Given the possibility that some nPB can be absorbed through the
skin in humans, and that the solvent can irritate the skin, EPA
encourages users to wear protective clothing and flexible laminate
gloves when using nPB and encourages vendors to include such
precautions in their Material Safety Data Sheets (MSDSs). EPA requests
comment on whether it would be useful, in lieu of a skin notation to
add the following statement in the ``further information'' column of
each end use where we find nPB acceptable with restrictions: ``EPA
recommends the use of personal protective equipment, including chemical
goggles, flexible laminate protective gloves and chemical-resistant
clothing, when using nPB.''
EPA also considered the potential health effects of contamination
of nPB formulations with isopropyl bromide
[[Page 30177]]
(iPB).\7\ In the June 2003 proposed rule, we proposed as a use
condition that nPB formulations contain no more than 0.05% iPB by
weight. One commenter opposed the proposed use condition, stating that
it places an undue legal burden on end users, rather than the
manufacturers of raw materials, that it would not benefit worker
safety, and that the nPB industry has worked to reduce iPB content
below 0.05% (Morford, 2003e). We agree that industry has met this
contamination limit for several years without regulation. Furthermore,
EPA agrees that if users are exposed to nPB concentrations no higher
than the highest potentially acceptable concentration (30 ppm), a
worker's exposure to iPB will be sufficiently low to avoid adverse
effects. Therefore, this proposed rule does not include a use condition
limiting iPB content in nPB formulations.
---------------------------------------------------------------------------
\7\ iPB is also referred to as 2-bromopropane, 2-propyl bromide,
or 2-BP. Its CAS registry number is 75-26-3.
---------------------------------------------------------------------------
1. Workplace Risks
In the June 2003 NPRM, EPA proposed that an exposure limit of 25
ppm would be protective of a range of effects observed in animal and
human studies, including reproductive and developmental toxicity,
neurotoxicity, and hepatotoxicity. Reduction of sperm motility in rats,
noted across multiple studies at relatively low exposures, was
determined to be the most sensitive effect. The Agency derived an
exposure limit of 18 ppm from a dose response relationship in male rat
offspring (``F1 generation'') whose parents were exposed to nPB from
prior to mating through birth and weaning of the litters (WIL, 2001).
We then proposed to adjust this value upwards to 25 ppm based on
principles of risk management, consistent with one of the original
``Guiding Principles'' of the SNAP program (59 FR 13046, March 18,
1994). As we discussed in the June 2003 NPRM, EPA noted that adhesives
users should be able to achieve an AEL of 25 ppm and that 25 ppm was
between the level based on the most sensitive endpoint (sperm motility
in the F1 offspring generation at 18 ppm) and the second most sensitive
endpoint (sperm motility in the F0 parental generation at 30 ppm).
Following SNAP program principles, we noted that ``a slight adjustment
of the AEL may be warranted after applying judgment based on the
available data and after considering alternative derivations'' (69 FR
33295). Because the animals were exposed to nPB for some time periods
that would not occur during actual occupational exposure, we stated
further that ``18 ppm is a reasonable but possibly conservative
starting point, and that exposure to 25 ppm would not pose
substantially greater risks, while still falling below an upper bound
on the occupation[al] exposure limit.''
Since the 2003 proposal, the Agency has reviewed both information
available at the time of the 2003 NPRM related to the health risks
associated with nPB use, as well as more recent case studies of nPB
exposures and effects in the workplace, newly published toxicological
studies, comments to the June 2003 NPRM, including new risk assessments
on nPB, and a new threshold limit value (TLV) issued by ACGIH.
OSHA has not developed a permissible exposure limit (PEL) for nPB
that EPA could use to evaluate toxicity risks from workplace exposure.
The ACGIH, an independent organization with expertise in industrial
hygiene and toxicology, has developed a final workplace exposure limit
of 10 ppm (ACGIH, 2005); however, as discussed below, EPA has concerns
about the documentation and basis of ACGIH's derivation.
The Agency reconsidered which exposure levels are likely to protect
against various health effects, based on review of all available
information. We summarize benchmark dose data for a number of endpoints
found in these analyses in Table 6 below. We examined these data to
assess the acceptability of nPB use in the aerosol solvent, adhesive
and coatings end uses reviewed in this proposed rule. These data
indicate that, once uncertainty factors are applied consistent with EPA
guidelines, the lowest levels for acceptable exposures would be derived
for reproductive effects.\8\ The data indicate that levels sufficient
to protect against male reproductive effects (e.g., reduced sperm
motility) would be in a range from 18 to 30 ppm,\9\ in the range of 17
to 22 ppm to protect against female reproductive effects (e.g., number
and length of estrous cycles), and at approximately 20 ppm for effects
related to reproductive success (live litter size).
---------------------------------------------------------------------------
\8\ By EPA guidelines, we would apply an uncertainty factor of -
10, or approximately 3, for differences between species for all
health effects. We would also apply an uncertainty factor of
[radic]10 (3) for variability within the working population for
reproductive and developmental effects, because, among other
reasons, these conditions would not necessarily screen out an
individual from being able to work, unlike for liver or nervous
system effects. Therefore, for reproductive and developmental
effects, we use a composite uncertainty factor of 10. See further
discussion of uncertainty factors in section V.C. below.
\9\ Based on WIL, 2001, as analyzed in ICF, 2002. The equivalent
values based upon Stelljes and Wood's (2004) analysis of WIL, 2001
would be slightly lower, from 16 to 28 ppm.
Table 6.--Summary of Endpoints Using Benchmark Response Modeling
----------------------------------------------------------------------------------------------------------------
Human
Benchmark dose equivalent
Endpoint a Study lowerbound concentration
(BMDL) b (ppm) (HEC) c (ppm)
----------------------------------------------------------------------------------------------------------------
Liver Effects d
----------------------------------------------------------------------------------------------------------------
Liver vacuolation in males (F1 offspring WIL, 2001 as analyzed in ICF, 2002 110 116
generation).
Liver vacuolation in males (F0 parent WIL, 2001 as analyzed in ICF, 2002 143 150
generation).
Liver vacuolation......................... ClinTrials, 1997b as analyzed in 226 170
ICF, 2002 and Stelljes & Wood,
2004.
----------------------------------------------------------------------------------------------------------------
Reproductive Effects--Male
----------------------------------------------------------------------------------------------------------------
Sperm motility (F1 offspring generation).. WIL, 2001 as analyzed in ICF, 2002 169 177
WIL, 2001 as analyzed in Stelljes 156 164
& Wood, 2004.
Sperm motility (F0 parent generation)..... WIL, 2001 as analyzed in ICF, 2002 282 296
WIL, 2001 as analyzed in Stelljes 263 276
& Wood, 2004.
Prostate weight (F0 parent generation).... WIL, 2001 as analyzed in TERA, 190 200
2004.
[[Page 30178]]
Sperm count............................... Ichihara et al., 2000b as analyzed 232 325
in Stelljes & Wood, 2004.
Sperm deformities (F0 parent generation).. WIL, 2001 as analyzed in Stelljes 296 311
& Wood, 2004.
----------------------------------------------------------------------------------------------------------------
Reproductive Effects--Female
----------------------------------------------------------------------------------------------------------------
Number of estrus cycles during a 3 week WIL, 2001 as analyzed in ICF, 2006 162 170
period (F0 parent generation). WIL, 2001 as analyzed in ICF, 2006 208 218
Estrous cycle length (F1 offspring WIL, 2001 as analyzed in TERA, 400 420
generation) d. 2004.
Estrous cycle length (F0 parent WIL, 2001 as analyzed in TERA, 210 220
generation) e. 2004.
No estrous cycle incidence (F1 offspring WIL, 2001 as analyzed in TERA, 180 189
generation). 2004.
No estrous cycle incidence (F0 parent WIL, 2001 as analyzed in TERA, 480 504
generation). 2004.
----------------------------------------------------------------------------------------------------------------
Reproductive Effects--Reproductive Success
----------------------------------------------------------------------------------------------------------------
Decreased live litter size (F1 offspring WIL, 2001 as analyzed in TERA, 190 200
generation). 2004.
Decreased live litter size (F2 offspring WIL, 2001 as analyzed in TERA, 170 179
generation). 2004.
Pup weight gain, post-natal days 21 to 28 WIL, 2001 as analyzed in TERA, 180 189
(F1 offspring generation). 2004.
----------------------------------------------------------------------------------------------------------------
Developmental Effects
----------------------------------------------------------------------------------------------------------------
Fetal body weight......................... WIL, 2001 as analyzed in TERA, 310 326
2004.
Fetal body weight......................... WIL, 2001 as analyzed in CERHR, 305 320
2002a.
----------------------------------------------------------------------------------------------------------------
Nervous System Effects
----------------------------------------------------------------------------------------------------------------
Hindlimb strength......................... Ichihara et al, 2000a as analyzed 214 300
in Stelljes and Wood, 2004.
----------------------------------------------------------------------------------------------------------------
a Unless explicitly stated, data are from a parental generation. Of the studies analyzed, only the WIL, 2001
study has multiple generations to be analyzed.
b The benchmark response value represents a specified level of excess risk above a control response.
c When considering workplace exposures, the human equivalent concentration is the BMDL, adjusted to apply to a
40-hour work week in which workers are exposed for 8 hours a day for five days per week. Animals in the WIL,
2001 study were exposed for 6 hours a day, 7 days a week. Animals in the Ichihara, 2000a and 2000b studies
were exposed for 8 hours a day, 7 days a week. Animals in the ClinTrials, 1997b study were exposed for 6 hours
a day, 5 days a week.
d After applying an uncertainty factor of 3 for animal to human extrapolation, acceptable levels of exposure to
protect against liver effects would be in the range of 39 to 57 ppm.
e Omits data from those animals that have stopped estrous cycling altogether (TERA, 2004).
2. General Population Risks
EPA used a community exposure guideline of 1 ppm to assess
potential risks to the general population living near a facility using
nPB (see section V.E below). Of the end uses covered in this rule, use
of nPB-based adhesives would result in the highest exposure levels, and
so, we first examined general population exposure from adhesives. ICF
Consulting modeled inhalation exposure to nPB to people living near a
plant using nPB-based adhesives in several scenarios using the Agency's
SCREEN3 model (US EPA, 1995b). Based on this modeling, EPA found that
the exposure to individuals in the general population was below the
community exposure guideline. The analysis indicates that nPB is no
greater a hazard to the general population than other acceptable
solvents under the SNAP program. For further discussion, see the risk
screen for nPB (ICF, 2006a).
Representatives from a state environmental agency and from a
potential user of nPB have asked EPA whether we had developed a
reference concentration (RfC). We clarify that the community exposure
guideline is a value developed by the SNAP program for our risk
assessment of nPB following EPA's RfC Guidelines. However, it is not a
formal RfC developed by EPA's National Center for Environmental
Assessment and is not in IRIS. At this time, EPA does not have plans to
issue an official RfC for nPB.
V. How did EPA assess impacts on human health?
A. Newly Available Exposure Data
Since publication of the June 2003 NPRM, EPA has received
additional information on exposure levels in each end use discussed in
this proposal.
In the adhesives end use, we considered new exposure modeling based
on information from site visits to facilities using spray adhesives
(ICF, 2006a). These data predicted that:
At average rates of ventilation and adhesive application,
average workplace exposures would be approximately 60 ppm.
Average adhesive application rates and poor ventilation
rates resulted in average exposures of approximately 250 ppm.
High (90th percentile) adhesive application rates and
average ventilation rates resulted in average exposures of
approximately 600 ppm.
In the worst case scenario with high adhesive application
rates and poor ventilation, average workplace exposures would be as
high as 2530 ppm.
We compared the modeled data in the four exposure scenarios to
measured exposure data in three health hazard evaluations by the
National Institute for Occupational Safety and Health (NIOSH) (NIOSH
2002a, 2002b, 2003a).
[[Page 30179]]
Our understanding is that North Carolina OSHA received complaints from
workers and requested that NIOSH evaluate health hazards at these three
facilities. NIOSH found average exposure levels of 68 ppm, 116 ppm, 127
ppm, and 195 ppm for sprayers actively using the adhesive prior to
installation of state-of-the-art ventilation systems (NIOSH 2002a,
2002b, 2003a). The plant with an average exposure level of 68 ppm for
sprayers (9 samples) had an average exposure level comparable to the
average concentration of 60 ppm in the modeling scenario with average
adhesive rates and average ventilation levels. The other plants with
average exposure levels of 116 to 127 ppm (20 samples), and of 195 ppm
(36 samples) for sprayers had exposure levels between the average
modeled exposure for a facility with average adhesive application rates
and average ventilation (60 ppm) and the average modeled exposure for a
facility with average adhesive application rates and poor ventilation
(250 ppm). Based on this comparison, EPA believes the modeled exposure
levels are a reasonable predictor of actual exposure based on current
industry practice in the adhesive end use.
In the aerosol solvent end use, we received a study on workplace
exposure levels of nPB-based aerosols from a commenter (Linnell, 2003).
This study was performed to simulate typical exposure levels in a
number of situations where nPB might be used in the workplace while
using different types of ventilation equipment, rather than using data
from current industry users of nPB-based aerosols in their actual
manufacturing or maintenance processes. As discussed below in section
VI.A., we are concerned that the exposure data and ventilation levels
in this study may not be representative of use of nPB-based aerosols in
industry. Personal breathing zone samples taken from the collars of
workers showed 8-hour time-weighted average (TWA) exposures of 5.5, 13,
and 32 ppm for workers using 310 g of nPB from a spray can \10\
(Linnell, 2003). The two higher exposure levels occurred in the absence
of any local or regional ventilation; the use of both local and
regional ventilation equipment with ventilation levels around 1900
ft3/min was associated with the lowest exposure level.
Short-term exposures of 370, 1,100 and 2,100 ppm taken from a room with
regional ventilation at 640 cubic feet per minute (cfm), when averaged
over an 8-hour period, resulted in exposures of 12, 34, and 66 ppm
(Linnell, 2003). EPA considers the highest of these 8-hour values, 66
ppm, not to be representative of worker exposure from inhalation
because the measurement was taken from the worker's wrist, rather than
from his breathing zone. Another short-term exposure value of 190 ppm,
taken from a vented booth with local ventilation at 472 cfm, in
addition to the regional ventilation of 640 cfm, resulted in an 8-hour
exposure of 6 ppm. Similar measurements were made in another study we
considered in developing the June 2003 NPRM: Eight hour (8-hr) TWA
exposures of 11.3, 15.1, 17.0, and 30.2 ppm with regional ventilation
of 300 cubic feet per minute from a fan for the entire room
(Confidential submission, 1998).
---------------------------------------------------------------------------
\10\ Unlike samples measured directly in the breathing zone,
area samples measured in the study are not considered representative
of actual exposure and are not discussed here. Short-term
measurements taken over 15 minutes from personal samplers, although
in some cases extremely high, are not discussed in detail here
because available toxicity information does not indicate need for a
short-term exposure limit for nPB in addition to the 8-hr TWA limit
(ACGIH, 2005; ERG, 2004). Additional information on these other
samples is in the occupational exposure assessment for aerosols in
the risk screen for nPB (ICF, 2006a).
---------------------------------------------------------------------------
Another commenter submitted information on aerosol exposures for a
number of other available alternative aerosols (Werner, 2003). While
these data do not include nPB, based on the properties of aerosol
solvents, we believe it is reasonable to compare concentrations of
these different chemicals to potential nPB exposures. The study
compared concentrations of eight different chemicals that are
acceptable under the SNAP program in aerosol formulations: HFE-7100,
HFE-7200, trans-1,2-dichloroethylene, HCFC-225ca and -225cb, acetone,
pentane, and HFC-134a. In this study, with ventilation of only 48 cfm,
8-hr TWA exposure from the different chemicals varied from 35.5 ppm to
194.0 ppm,\11\ below the recommended exposure levels for these
particular chemicals (ICF, 2006a) but above the range of exposure
levels that EPA would consider acceptable for nPB.
---------------------------------------------------------------------------
\11\ These measurements can be converted to estimates of nPB
exposure by multiplying the measured concentration of the alternate
chemical by the molecular weight of the same alternate chemical and
dividing this by the molecular weight of nPB, 123. After performing
this calculation, the equivalent exposure levels for nPB vary from
29.5 ppm to 394.4 ppm.
---------------------------------------------------------------------------
In addition, we considered new information from modeling of nPB
exposures (ICF, 2006a). The modeling examined exposure levels that
would be expected at ventilation levels of 450 cfm, 625 cfm, and 1350
ppm, considering the molecular weight of the compound and the
composition of different aerosol blends. EPA's SNAP program has
previously used these same levels to calculate potential aerosol
exposures, based upon exposure levels expected during benchtop
cleaning. In a space with an air exchange rate of 450 ft3/
minute or less,\12\ EPA's modeling predicts 8-hour average exposure of
approximately 16 to 17 ppm if a user sprays 450 g of nPB (approximately
1 lb),\13\ and corresponding higher exposure values at higher spray
rates (e.g., 33 ppm if the amount of nPB sprayed is 900 g) (ICF,
2006a). Exposure values were predicted to be lower at higher
ventilation rates.
---------------------------------------------------------------------------
\12\ This corresponds roughly to a regional or room fan at low
levels or natural air currents in an open area. Confined areas would
have even lower air exchange rates with higher exposure levels.
\13\ We consider use of 1000 g/day to be the high end of typical
use, based on the setup of one of the exposure studies (Confidential
Submission, 1998). The typical aerosol solvent user in the
electronics industry uses a can per day (Williams, 2005). This is
comparable to or slightly less than the spray rate assumed in the
modeling.
---------------------------------------------------------------------------
Since the June 2003 NPRM, EPA received a new submission for nPB in
coatings (Lake City Army Ammunition Plant, 2003). The Lake City Army
Ammunition Plant provided data on workplace exposure to nPB (Lake City
Army Ammunition Plant, 2004). The mean exposure at this facility was
3.7 ppm. Out of 31 samples taken, 25 (approximately 80%) were below 5
ppm. Only one of 31 samples had an exposure level above 10 ppm, and
that exposure value was approximately 21 ppm.
B. Newly Available Data on Health Effects
Since publication of the June 2003 NPRM, EPA has examined
additional occupational (Table 7) and animal (Table 8) studies that
have become available:
[[Page 30180]]
Table 7.--Recent Studies on nPB Occupational Exposure
----------------------------------------------------------------------------------------------------------------
Sample size/
Case Study population Exposure data Observations Remarks
----------------------------------------------------------------------------------------------------------------
Beck and Caravati, 2003....... 6 foam cushion Exposure during Lower leg weakness Small sample size
factory workers 30-40 hr/wk for accompanied by pain studied. Possible
(gluers). a 3-month and difficulty with interference or
period. standing and synergistic effects
Exposure walking, numbness of from other adhesive
measured in one legs and feet, ingredients (1,2-
day was a mean hyperreflexia and epoxybutane and
of 130 ppm hypertonicity of styrene-butadiene).
(range, 91-176 lower extremities,
ppm). dizziness and
shortness of breath,
and peripheral
neurotoxicity.
Measured serum
bromide levels were
elevated, range 44-
170 mg/dL.
Majersik et al., 2004; 6 foam cushion 5-8 hr/day for Subacute onset of Follow-up to Beck and
Majersik et al., 2005 *. factory workers at least 2 lower extremity Caravati (2003).
(gluers). years with mean pain, difficulty Chronic nPB exposure
air walking, and high associated with
concentration serum bromide levels incapacitating
of 130 ppm on in blood. Neurotoxic neurotoxic syndrome.
last day of symptoms persisted Initial report from
study. for at least 2 years Utah OSHA indicated
Measurements after exposure ended. erroneously that
taken over 9 workers were not
hours spraying while
(equivalent to measurements were
92-127 ppm with taken. In fact,
mean of 108 ppm adhesives were being
for an 8-hour sprayed and fans
TWA). were being used only
for portions of the
day that
measurements were
taken, making
measurements likely
to be representative
of conditions during
the past several
months at the plant.
Ichihara et al., 2004a........ 37 chemical 12 hour shifts Mucosal irritation Inadequate exposure
plant workers over 2-day (nose, throat), characterization and
(24 males and period, mean headache, dizziness, exposure to other
13 females). concentration constipation, potential toxicants,
of 82 ppm intoxication, and small sample size,
(range, 0-170 feeling light-headed and no appropriate
ppm). or heavy-headed. control group.
Four female workers Healthy worker
complained of effect possible,
disruption or where more sensitive
cessation of workers left the
menstruation. No factory between 1996
severe chronic and 1999.
symptoms of
neurological damage
at less than 170
ppm. Several workers
had hemoglobin and
hematocrit values
outside of the
normal range and
were diagnosed with
mild anemia; most of
these cases also
showed signs of iron
deficiency.
Ichihara et al., 2004b........ 27 female 1-day exposure Responses indicated No long-term exposure
chemical plant period, range anxiety, fatigue, measurements, small
workers (23 age of exposure, confusion, tension, sample size; lack of
matched with 23 0.34-49 ppm. and depression. controls for age,
females from a Changes in menstrual height, and body-
beer factory status but not weight. Low B
control group). statistically vitamin levels in
significant. Effects normal range in some
on peripheral and workers but
central nervous researchers
system--diminished concluded this did
vibration sensation not cause observed
of the foot; neurological
significantly longer effects.
distal latency in Additionally, the
the tibial nerve; study did not
decreased values in indicate any
sensory nerve significant
conduction velocity differences in the
in the sural nerve; prevalence of
and lower scores on menstrual cycle
memory and abnormalities.
perceptual tests. No
comparable effects
seen in control
group.
Nemhauser, 2005 *............. Foam cushion In 1999 study, Higher exposure to Small sample sizes
factory workers 16 workers nPB and dose- studied with
(gluers) in exposed to mean dependent moderate worker
North Carolina. air relationship among participation.
concentration those who reported Healthy worker
of 116 ppm, and anxiety, headache, effect likely
12 sprayers and ataxia. No occurred: Those that
exposed to mean reproductive had most significant
concentration abnormalities health effects had
of 108 ppm with reported in medical already removed
range of 58 to survey for men or themselves from
254 ppm. In women. Semen workplace by the
2001 study, 13 analysis found no time of the study.
workers exposed differences between No arsenic found at
to nPB mean air exposed and the plant.
concentration unexposed workers. Neurotoxic effects
of 46 ppm and caused by nPB. See
12 sprayers related Health
were exposed to Hazard Evaluation
mean (HHE): NIOSH, 2003a.
concentration
of 101 ppm,
with range of
38 to 281 ppm.
NIOSH, 2003a.................. 16 workers in 1999 Initial Most workers exposed Arsenic was not
1999 Site Visit: to nPB levels > 25 attributed to
evaluation; 13 Geometric mean ppm. Exposure occupational
workers in 2001 nPB concentrations lower exposure. The
follow-up concentration in 2001 than 1999, National Institute
evaluation. (from personal but difference not for Occupational
samples), 81.2 statistically Safety and Health
(range, 18-254 significant. (NIOSH) stated that
ppm); 2001 Headache, anxiety, neurological
follow-up: feeling drunk symptoms may have
Geometric mean, associated with nPB been related to
81.2 ppm exposure. excess exposure to
(range, 7-281 Hematological nPB, but that no
ppm). endpoints unaffected other effects could
in exposed group. No conclusively be
correlation of nPB related to nPB
exposure with sperm exposure.
or semen indices or
with neurological
abnormalities.
[[Page 30181]]
Raymond and Ford, 2005 *...... 4 foam cushion Exposure study Dizziness, numbness, Small sample size,
factory workers conducted 9 ocular symptoms, possible confounding
(gluers) in months after lower extremity effect from arsenic.
North Carolina. index patient weakness and
became ill unsteady gait,
indicated weakness,
workers exposed hypesthesia, and
to mean nPB air ataxic gait in all
concentration four workers.
of 116 ppm. 4 Symptoms decreased
workers exposed over time but after
for 2-3 weeks six years, at least
before initial one worker re-
symptoms exposed twice at
detected. other furniture
plants; one or more
still suffer from
ataxia.
Toraason et al., 2006......... 41 and 22 foam 1-3 days up to 8 No statistically Authors find limited
cushion factory hrs per day, significant evidence that nPB
workers with differences in DNA poses a ``small
(gluers) at 2 concentrations damage with worker's risk'' for DNA
facilities. of 0.2-271 ppm nPB exposure. In damage.
at facility A, vitro results showed
4-27 ppm at nPB increased DNA
facility B. damage.
----------------------------------------------------------------------------------------------------------------
* Presentation at North American Congress of Clinical Toxicology on September 14, 2005.
Table 8.--Recent Animal Studies of nPB Effects
--------------------------------------------------------------------------------------------------------------------------------------------------------
Population/sample
Citation size Exposure Observations Comments
--------------------------------------------------------------------------------------------------------------------------------------------------------
Fueta et al., 2002................ 24 male Wistar rats 6 hr/day, 5 day/wk No apparent morphological defects Only one exposure concentration was
(12 control, 12 for 8 weeks at 700 in the brain. used (which is higher than the
exposed). ppm. level already associated with
other toxic effects in rodents
[400 ppm]) and a shorter exposure
duration (8 weeks) was used than
the other subchronic studies that
have shown effects (13 weeks).
Fueta et al., 2004................ 58 male Wistar rats 6 hr/day, 5 day/wk No apparent morphological defects Unclear how nPB and/or its
(29 experimental for 4 to 8 weeks, in the brain. Chronic inhalation metabolites directly act on
and 29 in control 700 ppm. changes brain enzyme levels and receptors or channels in the
group). electrical activity that is brain.
reversible after exposure.
Furuhashi et al., 2006............ 80 Wistar rats (pups (1) 8 hr/day (4 hr, (1) At 800 ppm: most rat offspring Authors concluded that exposure to
and their dams). followed by 2.5-hr died within 2 days of birth or in nPB during pregnancy and lactation
rest period, utero;. body weights of dams adversely affects growth and
followed by 4 hr significantly lower, organ weights survival of offspring. Low numbers
exposure), 7 day/wk of offspring significantly lower of offspring in 400- and 800-ppm
during gestation after weaning at 800 ppm in males, exposure groups prevent
and nursing at 0, and 800 and 400 ppm in females. statistical testing
100, 400, 800 ppm Most sperm and estrous indicators EPA comments: Study design
in first experiment. did not differ among the groups, inconsistent with guidelines for
(2) Dams exposed although the rate of sperm arrival developmental studies, so
(800 ppm) during to the cauda epididymis was comparisons to previous studies
gestation (Group significantly lower in the 400 ppm are difficult. The mechanism for
A), offspring not group. Inconsistent or no changes the adverse effects observed is
exposed during in biochemical indicators. not known (e.g., indirect exposure
nursing. Offspring (2) Second experiment No difference through milk, changes in nursing
of Group (B) of in body weights and pregnancy behavior, changes in milk
unexposed dams were endpoints between exposed (800 production, exposure in utero,
nursed by exposed ppm) and unexposed dams. Live changes in the intrauterine
dams. Offspring in offspring at birth, survival environment)
control groups C rates, body weights, significantly
and D not exposed. decreased, number of dead
offspring, significantly increased
in 800-ppm groups.
Honma et al., 2003................ Fisher 344 male rats 8 hr/day, 7day/wk 3 week exposure to greater than 50 Neurological effects shown to be
for three weeks ppm temporarily increased transient and reversible at >= 200
exposed to 0, 10, locomotor activity and ambulatory ppm (Ichihara et al., 2000) or
50, 200 or 1000 ppm and rearing behaviors in male rats. absent after 28 days of exposure
(5 rats/dosage and at concentrations >= 400 ppm
5 different tests). (ClinTrials, 1997a) or after 90
days of exposure at concentrations
up to 600 ppm (ClinTrials, 1997b)
in other studies. Human studies
are limited by co-exposures and
poor estimates of exposure
concentrations. Thus, EPA is not
using this endpoint as the basis
of an AEL.
[[Page 30182]]
Ishidao et al., 2002.............. 30 male Wistar rats. 6 hr/day, 5 day/wk nPB is metabolized rapidly in the Exposure levels are higher than in
with test groups rat following exposures to nPB at some other studies and are much
(10/dose) exposed concentrations >= 700 ppm for at higher than concentrations seen in
to 700 ppm for 4 least 3 weeks. the workplace. nPB metabolism
and 12 weeks and appears to be different following
1500 ppm for 3 and multiple exposures as compared to
4 weeks. acute exposures (see RTI, 2005;
ICF, 2006b).
NTP, 2003......................... Female and male 0, 62.5, 125, 250, Early mortality in mice at 500 ppm Unpublished study. Conclusions
B6C3F1 mice and 500 (rats and accompanied by liver and lung cell drawn from a review of raw data
Fischer 344 rats. mice), 1000 (rats) degeneration and cytoplasmic from the National Toxicology
ppm for 90 days. vacuolization. Cytoplasmic Program (NTP) Web site. In
vacuolization also in rat liver general, the severity of effects
cells >= 250 ppm (males) and >= (in non-reproductive organs) is
500 ppm (females), with increased slightly higher at lower
severity at higher doses. No concentrations in male rats than
adverse central nervous system in females.
(CNS) effects or histopathology
reported.
RTI, 2005/Garner et al., 2006..... Female and male Exposure via several nPB cleared by mice after 48 hours The study authors concluded that:
B6C3F1mice and injection routes as follows: 45% as volatiles in nPB administered via
Fisher 344N rats, (intraperitoneal, the breath, 28% as CO2 in the intraperitoneal injection or
four to six animals intravenous, breath, 26% in urine, <3% in inhalation is eliminated mostly
in each test trial. cannuliz-ation), feces, and 2% retained in the through the breath, with urine as
inhalation, and body. Distribution was similar in a secondary path.
dermal. Injection male rats, although amounts in Metabolism of nPB appears
conducted via bolus urine and volatiles in breath were to be primarily through cytochrome
dosing at 5, 20, or higher in mice. At higher doses, P450 enzymes (CYP2E1),
100 mg/kg body the amount of nPB excreted in particularly in mice; glutathione
weight. Inhalation urine and as CO2 decreased, with a conjugation still plays an
concentrations of much greater change in rats important role in rats.
70, 240, 800, and compared to mice. At high concentrations,
2700 ppm After pretreatment with a female rats may have a decreased
administered in a cytochrome P450 inhibitor, a capacity to metabolize nPB
single acute decrease in nPB cleared as CO2 compared to male rats.
exposure. A dose of (80%) and urine (40%); nPB decreases glutathione
96 mg/kg was pretreatment with a glutathione levels in the liver after a one-
applied to a shaved inhibitor reduced nPB cleared as time exposure to nPB at
area on the backs CO2 by 10% and urine by 4%. concentrations as low as 70 ppm.
of six male rats The Vmax, a measure of the nPB is not appreciably
with a non- maximum initial rate of an enzyme- absorbed (~3-27%) in rats
occlusive charcoal catalysed reaction, is 0.227 for following dermal application.
filter covering male rats, 0.143 for female rats, EPA agrees with these points,
(that is, one that 0.329 for male mice and 0.234 for except we found that gender
does not prevent female mice. Half-lives were differences were only apparent in
evaporation). comparable between males and rats at very high concentrations
females at <= 800 ppm. (2700 ppm and greater). We also
For rats exposed to nPB note that:
through skin, 37% of the dose was Inhalation tests were only
excreted in volatiles, 1.2 % in one-time exposures at very high
urine, 1.7% as CO2, and 35.7% was concentrations (240 to 2700 ppm),
on the applicators or in the skin and thus, are not comparable to
washes. Only 0.32% remained in long-term dosing at the lower
tissues. Airborne concentrations levels expected in the workplace.
of nPB in the chamber were 4 to 10 Results of dermal testing
ppm after dosing. are not conclusive because of
potential for inhalation exposure.
Sohn et al., 2002................. 40 male and 40 6 hr/day, 5 day/wk No effects on mortality, activity, The differences between the various
female Sprague- for 13 weeks, test weight gain, food consumption, studies may be due to variability
Dawley rats. groups (10/sex/ urinalysis, or histological in exposure methodology and
dose) were exposed effects in the brains and spinal achieved concentrations of nPB.
to 0, 200, 500 or cords.
1250 ppm.
Stump, 2005*...................... 125 female/125 male Both test groups of Decreased litter size at 250 and Reproductive effects seen in both
rats in first 25 male rats/ 25 500 ppm in both generations. rat sexes which is a strong signal
generation and 100 female rats exposed Decreased fertility at 100 and 250 of reproductive toxicity potential
female/100 male to 0, 100, 200, ppm in offspring generation. in humans. The author considers
rats in offspring 250, 500 and 750 Complete infertility at 750 ppm.... 100 ppm to be a lowest observed
generation. ppm nPB for 10 adverse effect level (LOAEL). This
weeks. is a presentation of data from
WIL, 2001.
Wang et al., 2003................. 36 male Wistar rats. 8 hr/day, 5 day/wk Decrease in creatine kinase in the Small study size. No behavioral
for 12 weeks, test spinal cord (17% at >= 200 ppm) changes or physical symptoms were
groups ( 9 rats) and brain (15-28% at >= 400 ppm) observed in the animals, so the
were exposed to 0, at 200, 400, and 800 ppm. No toxicological relevance of the
200, 400 or 800 ppm. physical or behavioral changes decrease in creatine kinase is
observed. questionable.
Yamada et al., 2003............... 40 female Wistar 8 hr/day, 7 day/wk All rats at 800 ppm became Data suggest that nPB is affecting
rats. with test groups (9/ seriously ill after 7 weeks of the maturation of ovarian
dose) exposed to 0, exposure. Significant decrease in follicles. A no observed adverse
200, 400, or 800 antral follicles at >= 200 ppm, effect level (NOAEL) of 200 ppm is
ppm for 12 weeks. and a decrease in the number of identified with a LOAEL of 400 ppm
female rats exhibiting regular for the changes in estrus cycles.
estrous cycles in 400-ppm females
during 7-9 weeks of exposure and
at 2-3 weeks at the 800-ppm dose.
--------------------------------------------------------------------------------------------------------------------------------------------------------
* Presentation at North American Congress of Clinical Toxicology on September 14, 2005
[[Page 30183]]
In general, the recent animal studies collectively show a
range of effects associated with nPB exposure that are qualitatively
consistent with previously published findings. (Exceptions to this are
the negative results regarding central nervous system toxicity in the
NTP (2003) study and the Sohn (2002) study on rats.) Some general
conclusions we draw from the new studies include:
Case reports of nPB exposure in the workplace indicate
that severe, possibly irreversible, neurological effects may occur at
sustained concentrations of approximately 100 ppm or greater (Beck and
Caravati, 2003; Majersik et al, 2004; Majersik et al., 2005; Ichihara
et al., 2002a; Miller, 2005; Raymond and Ford, 2005). In other cases,
similar or higher concentrations up to 170 ppm caused less severe
nervous system effects (Nemhauser, 2005; NIOSH, 2003a; Ichihara,
2004a). Some neurological effects occurred in workers at levels of less
than 50 ppm (Ichihara et al., 2004b). Because of design and
methodological limitations, such as small numbers of subjects and
limited exposure information, these studies do not provide a sufficient
quantitative basis to derive an acceptable exposure limit.
Data on female rats indicate that nPB affects the
maturation of ovarian follicles and the ovarian cycle (Yamada et al.,
2003), consistent with previously reviewed data (WIL , 2001; Sekiguchi
et al., 2002).
Some data on occupation exposure suggest that workers
exposed to nPB may have experienced menstrual disorders (Ichihara et
al., 2002; Ichihara et al., 2004b). However, the data are not
statistically significant and are not sufficient to conclude that nPB
exposure caused these female reproductive effects.
Data on DNA damage in workers exposed to nPB was not
statistically significant (Toraason et al., 2006).
Metabolic data on mice and rats indicate some species
differences. Metabolism of nPB appears to be primarily through
cytochrome P450 enzymes, particularly in mice; glutathione conjugation
also plays a role, and a bigger role for rats than for mice (RTI,
2005).
New data from toxicological studies on nervous system
effects remain inconsistent and equivocal concerning the level at which
nervous system effects occur (Fueta et al., 2002; Fueta et al., 2004;
Honma et al., 2003; Ishidao et al., 2002, NTP, 2003; Sohn et al. 2002,
Wang et al., 2003).
A number of commenters on the June 2003 NPRM suggested that EPA
should consider neurotoxicity as the endpoint in deriving an AEL for
nPB (Linnell, 2003; Werner, 2003; Rusch and Bernhardt, 2003, Rusch,
2003). In particular, they requested that EPA consider the study
conducted by Wang (2003) and epidemiological data on neurotoxic effects
of nPB. As discussed above, the data on neurotoxic effects of nPB on
workers are limited and are not sufficient to determine acceptable
levels of exposure. In the study on rats by Wang et. al. (2003),
measurements found a decrease in enzymes in the spinal cord and brain
at 200, 400, and 800 ppm, but the animals displayed no physical or
behavioral changes. Because of the lack of physical symptoms or
behavioral changes, EPA does not believe that the decrease in enzyme
levels in the central nervous system are toxicologically relevant.
Other studies examining neurological effects of nPB showed those
effects to be transient and reversible at and above 200 ppm (Ichihara
et al., 2000a). Exposures of 200 ppm and above for three weeks had no
effect on memory, learning function, or coordination of limbs (Honma,
2003); the effect of spontaneous locomotor activity seen in this study
at 50 ppm and above was not considered adverse by the authors. In other
studies, neurological effects were absent after extended periods of
exposure-after 28 days of exposure at concentrations > 400 ppm
(ClinTrials, 1997a) and after 90 days of exposure at concentrations up
to 600 ppm (ClinTrials, 1997b). Thus, although neurological effects
have been associated with nPB exposure, the data are currently
insufficient to quantify and determine acceptable exposure levels based
on this endpoint.
One commenter on the June 2003 NPRM requested that EPA evaluate a
study by Yamada et al. (2003), a study published just prior to the June
2003 NPRM. In response to the comment, EPA reexamined Yamada et al.,
2003 and re-evaluated the literature (Ichihara et al., 1999, 2002,
2004a,b; Sekiguchi, 2002, Yamada et al., 2003; WIL, 2001) to assess
potential reproductive toxicity in females (ICF, 2006a, Att. A). A peer
review of these effects is in the public docket (ICF, 2004b). Multiple
benchmark analyses found a statistically significant decrease in the
number of estrous cycles and increase in estrous cycle length
associated with nPB exposure, consistent with other reproductive
endpoints, namely reductions in sperm motility, decreased live litter
size, and change in prostate weight (ICF, 2002a; ICF, 2006a; Stelljes
and Wood, 2004; TERA, 2004).
Reproductive effects are seen in males, females, and offspring, and
in different generations of the two-generation study (WIL, 2000). They
also are consistent with results seen in one-generation reproductive
studies, such as Ichihara et al. (2000b) and Yamada (2003). See Table 6
above in section IV.E.1. for a more complete list of the different
health effects. EPA believes that the preponderance of the data
indicate that exposure levels sufficient to protect against male
reproductive effects (e.g., reduced sperm motility) would be in a range
from 18 to 30 ppm, in the range of 17 to 22 ppm to protect against
female reproductive effects (e.g., number and length of estrous
cycles), and at approximately 20 ppm for effects related to
reproductive success (live litter size). We have not determined what
specific level within those ranges (an overall range of 17 to 30 ppm)
is most appropriate for evaluating whether a substitute may be used
safely and consider these exposure levels to be potentially acceptable.
Therefore, we assessed the acceptability of nPB by considering whether
it could be used safely in the three end-uses. For end-uses with
likelihood of exposures above the range we are considering, while
following typical industry practices, we are proposing an
unacceptability determination. For end-uses that as their normal
practice meet exposure levels below the range we are considering, we
are proposing an acceptability determination. It is not necessary for
100% of exposure data for an end use to be above or below the range of
17 to 30 ppm in order to make a determination on the acceptability of
an end use because there may be occasional cases that are not following
common industry practices. Unusual events would not indicate the
industry's likelihood of keeping exposures at safe levels, and thus,
should not be the determining factor in our decision. Rather, we
consider the overall likelihood that typical industry use would
consistently result in acceptably low or unacceptably high exposures.
In the June 2003 NPRM, EPA used a BMDL of 169 ppm as a point of
departure for developing an AEL. Some commenters stated that data from
the F1 generation is inappropriate for calculating occupational
exposure, citing statements from toxicologists, such as, ``occupational
exposure involves adults only.'' They also stated that EPA has not
required this for other chemicals and that the resulting value is more
conservative than what is normal and appropriate for industrial
toxicology (Morford, 2003f, Ruckriegel, 2003). Others stated that sperm
motility effects on the F1 generation are appropriate to consider
(Risotto, 2003; Farr, 2003), particularly because of the
[[Page 30184]]
potential for in utero effects and because of the consistent presence
of these reproductive effects in both generations and at multiple
levels. EPA acknowledges that using data from the F1 offspring
generation may be conservative because the pups in the F1 generation
were exposed to nPB between weaning and sexual maturity (WIL, 2001).
During occupational exposure, this period of exposure would not occur
because children under age 16 are not allowed to work in industrial
settings. However, EPA believes that because of the potential for in
utero effects that would only be seen in the offspring generation,
looking only at the F0 parental generation could underestimate the
adverse health impacts of a chemical. Therefore, we believe it is
appropriate to consider effects seen in both the F0 parental generation
and the F1 offspring generation. Further, effects on sperm motility in
the parental and offspring generations are seen at levels generally
consistent with multiple reproductive effects seen in both generations
and both sexes exposed to nPB, such as estrous cycle length, lack of
estrous cycling, the number of estrous cycles in a given period of
time, fertility indices, and the number of live pup births (TERA, 2004;
ICF, 2006a; SLR International, 2001). Therefore, we believe that the
available data indicate that in order to protect against adverse
reproductive effects, an exposure level within the range of 17 to 30
ppm, would potentially be acceptable. We would reach the same proposed
decisions of unacceptability based upon data from the F0 generation.
C. Evaluation of Acceptable Exposure Levels for the Workplace
To calculate acceptable exposure levels for nPB, EPA uses standard
risk assessment methods delineated in Agency guidance (U.S. EPA, 1994b)
in evaluating data, choosing a benchmark dose level or a NOAEL, and
making the adjustments and uncertainty factors prescribed to account
for differences in the duration of exposure and in sensitivity between
and within species.
Adjustment for Occupational Exposure Pattern
To account for differences between the exposure pattern used in the
WIL study (6 hours per day for 7 days per week) when compared to a
typical workweek of 8 hours per day and 5 days a week, a ``human
equivalent concentration'' (HEC) is first calculated by adjusting the
benchmark dose level:
(BMDL in ppm x 6 hours/8 hours) x 7 days/5 days = HEC (ppm)
HECs for the major health endpoints are shown in Table 6 above in
section IV.E.1.
Uncertainty Factors
According to EPA risk assessment guidance for reference
concentrations (RfC) (EPA 1994a), uncertainty factors of up to 10 may
be applied to the HEC for each of the following conditions:
(1) Data from animal studies are used to estimate effects on
humans;
(2) Data on healthy people or animals are adjusted to account for
variations in sensitivity among members of the human population (inter-
individual variability);
(3) Data from subchronic studies are used to provide estimates for
chronic exposure;
(4) Studies that only provide a LOAEL rather than a NOAEL or
benchmark dose; or
(5) An incomplete database of toxicity information exists for the
chemical.
EPA believes that two uncertainty factors are appropriate for this
database to account for that: (1) Physiological differences between
humans and rats; and (2) variability within the working population. The
rationale for the use of these two uncertainty factors is described
below.
EPA RfC guidelines state that an uncertainty factor of 10 may be
used for potential differences between study animals and humans. This
factor of 10 consists in turn of two uncertainty factors of 3--the
first to account for differences in pharmacodynamics \14\ and the
second to account for differences in pharmacokinetics \15\ between the
study of animal and humans. (The value of three is the square root of
10 rounded to one digit, with 10 representing an order of magnitude
(EPA,1994a). In practice, EPA uses the square root of 10 when there are
two or four uncertainty factors of 3, yielding a total uncertainty
factor of 10 or 100, and we use a value of 3 when multiplying by an
uncertainty factor of 10). By EPA RfC guidelines (U.S. EPA, 1994b), no
adjustment for differences in pharmacokinetics is necessary in this
instance because the blood/air partition coefficient \16\ for nPB in
the human (7.1) is less than in the rat (11.7), indicating that the
delivered dose of nPB into the bloodstream in rats is slightly higher
than in humans. Consistent with Appendix J of EPA's RfC guidelines for
an inhaled compound that exerts its effects through the bloodstream,
EPA applies an uncertainty factor of 1 for pharmacokinetics.
---------------------------------------------------------------------------
\14\ Pharmacodynamics refers to the biochemical and
physiological effects of chemicals in the body and the mechanism of
their actions.
\15\ Pharmacokinetics refers to the activity or fate of
chemicals in the body, including the processes of absorption,
distribution, localization in tissues, biotransformation, and
excretion.
\16\ The blood/air partition coefficient is the ratio of a
chemical's concentration between blood and air when at equilibrium.
---------------------------------------------------------------------------
However, EPA recognizes that the lack of an uncertainty adjustment for
pharmacokinetic differences between animals and humans rests on a
default approach applied to category 3 gases described in Appendix J of
its guidelines for deriving an inhalation RfC. This default approach
assumes that nPB's toxicokinetics follow a model in which: (1) The
toxicity is directly related to the inhaled parent compound in the
arterial blood, and (2) the critical metabolic pathways scale across
species, with respect to body weight, in the same way as the
ventilation rate. Given the hypothesized metabolic pathways for nPB
(ICF, 2002a; CERHR, 2002a), it is plausible that toxicity in rats may
be related to a reactive metabolite in the target tissue rather than
the blood level of the parent compound. EPA is not aware of any
quantitative data on nPB metabolism in humans, or evidence implicating
the biologically active agent or mode of action. Some commenters on the
June 2003 NPRM stated that EPA should use an uncertainty factor of 1 or
2 to extrapolate from animals to humans (Weiss Cohen, 2003), while
others suggested uncertainty factors of 2 or 3 for pharmacokinetics, or
an overall uncertainty factor of 10 for rat to human extrapolation
because of a lack of information on the metabolism and mode of action
of nPB and because the rat is an insensitive model for effects on male
reproduction in humans (Werner, 2003; Rusch and Bernhardt, 2003).
Commenters provided no data to indicate that (1) the toxicity is not
directly related to the inhaled parent compound in the arterial blood,
or (2) the critical metabolic pathways do not scale across species,
with respect to body weight, in the same way as the ventilation rate.
Recent studies provide additional data regarding metabolism of nPB in
rats and mice (RTI, 2005), but data on human metabolism are still
lacking.
One analysis of these metabolic data suggested that mice are less
sensitive to the effects of nPB than rats and hypothesized that humans
would also be less sensitive than rats (Stelljes, 2005). However, this
analysis makes numerous assumptions about toxic nPB metabolites and
metabolic activation pathways that have not been confirmed by
experimental data. A review of this
[[Page 30185]]
analysis is available in the public docket (ICF, 2006c). Despite the
difference in metabolic pathways for nPB in mice and rats (RTI, 2005),
EPA finds no significant species-specific differences in toxicity exist
between rats and mice at inhaled concentrations <500 ppm for 13 weeks
(NTP, 2003; ICF, 2006b). These metabolic and subchronic inhalation
studies conducted under the National Toxicology Program did not
specifically examine for reproductive toxicity or nPB metabolism in
target organs that control reproductive function. In summary, there are
little available data about the metabolic activation or reactive
metabolites responsible for reproductive toxicity in rodents.
Similarly, for nPB, there is little information available about
differences and similarities between rodents and humans. Given this
circumstance, EPA assumes, in the absence of evidence to the contrary,
that nPB toxicity is directly related to the inhaled parent compound in
the arterial blood and that the critical metabolic pathways scale
across species in a manner similar to the ventilation rate. Therefore,
the Agency is proposing to apply an uncertainty factor of 1 to account
for interspecies differences in pharmacokinetics.
EPA requests additional data and comment from the public on the
pharmacokinetics, metabolism, and mode of action of nPB that will help
determine whether an interspecies uncertainty factor greater than the
default value of 1 is warranted to account for pharmacokinetics. If
data become available indicating that nPB does not conform to the
constraints assumed by the default pharmacokinetic model in the RfC
guidelines, we would revise our risk assessment for nPB as necessary,
and apply an uncertainty factor for pharmacokinetics consistent with
the RfC guidelines in extrapolating from animal to humans. Depending on
the resulting difference in the acceptable exposure levels, we would
also revise our acceptability determinations accordingly. Given the
available data on the blood/air partition coefficient and EPA RfC
guidance in the absence of other information, EPA is applying the same
rationale used for other compounds reviewed under EPA's SNAP program
with a comparable amount of data where an uncertainty factor of 1 for
pharmacokinetics was applied. To account for uncertainty in
pharmacodynamics of nPB, EPA is applying the default uncertainty factor
of 3. This follows the procedures in EPA's RfC guidelines for
situations where there are no data to compare pharmacodynamics in rats
versus humans (U.S. EPA, 1994b). Recently published data on humans and
rodents do not decrease the uncertainty regarding the pharmacodynamics
of nPB; therefore, modification of the uncertainty factor of 3 for
differences between species is not justified.
One commenter stated that EPA did not cite any data that describes
the size, condition, or very existence of a subpopulation of men
especially sensitive to the effects of nPB. In addition, this commenter
asserted that sensitive populations are not traditionally considered
when deriving an occupational exposure limit, and that EPA has never
mentioned a concern with sensitive subpopulations in previous SNAP
reviews.
EPA disagrees with the comments. There are preexisting reproductive
conditions as well as significant variability in fertility among
otherwise healthy adults in the workplace. Women over age 35 and men
over age 40 have fertility rates up to three times lower than those of
people in their twenties, with effects on the ovarian cycle and on
sperm motility as major factors changing with increasing age for women
and men, respectively (Dunson et al., 2002). Adding damage from other
factors, such as smoking or occupation exposure to chemicals such as
nPB, therefore, can potentially harm an individual's ability to
reproduce further (Dunson, et al. 2002). In addition, we note that EPA
has used uncertainty factors in the past to protect sensitive
subpopulations on other chemicals reviewed under the SNAP program
(e.g., trifluoroiodomethane at 69 FR 58907, October 1, 2004). For
deriving AELs from health endpoints such as liver effects and
neurotoxicity, the SNAP program typically has assigned an uncertainty
factor of 1 for sensitive subpopulations because we assume that
individuals who are especially susceptible to these effects will have
greater difficulty working than most people. However, there is no
connection between the ability to reproduce and the ability to work in
the industrial sectors discussed in this rule. Thus, we find it
appropriate to apply an uncertainty factor greater than 1 for
reproductive effects.
Some commenters on the June 2003 NPRM said that an uncertainty
factor of 1 is appropriate for variability within the working
population because sensitive subpopulations will not be present in the
working population (Stelljes, 2003, Morford, 2003f). Other commenters
stated that there will be very little difference in variability between
the worker population and the general population and that it is unclear
why EPA selected an uncertainty factor of 3 instead of 10 (Werner,
2003). Commenters suggested uncertainty factors for variability in the
working population of 1, 2, and 5 (Stelljes, 2003; Weiss Cohen, 2003;
Werner, 2003).
EPA's RfC guidelines recommend an uncertainty factor of 10 to
account for intraspecies variability within the general population.
However, in deriving an acceptable exposure limit, EPA's focus is on
worker exposure, which excludes some particularly vulnerable
populations, such as children, most adolescents, and the elderly. Thus,
we believe that a full uncertainty factor of 10, as for the general
population, may be higher than necessary to protect workers. However,
because of variability in reproductive function due to factors present
among workers, such as aging, smoking, and sexually transmitted
disease, and because there is no screening of workers that would make
workers more likely to have healthy reproductive systems than non-
workers of the same age, we believe than an uncertainty factor of 1 is
not sufficiently protective. Under EPA guidelines, 3 is a default value
for an uncertainty factor where there is indication that a value less
than an order of magnitude (10) but greater than one is appropriate,
and where the available data are not sufficiently quantified to select
a specific value. Therefore, EPA is again proposing to assign an
uncertainty factor of 3 to account for difference between individuals
in the working population.
The uncertainty factors of 3 for animal-human extrapolation and 3
for variability within the human working population (each representing
the square root of ten, half an order of magnitude) yield a composite
uncertainty factor of 10. This factor was applied to all HECs derived
from reproductive studies summarized in Table 6 in section IV.E.1
above. The resultant values are higher than the value that would have
been obtained had EPA used the TLV of 10 ppm developed by the ACGIH.
EPA believes that the benchmark dose approach more accurately
characterizes the observed effects and provides a more robust
utilization of the data.
D. Other Analyses of nPB Toxicity
Analyses Reviewed During Preparation of June 2003 NPRM
One commenter on the June 2003 NPRM stated that documents by Drs.
Doull, Rozman, Stelljes, Murray, Rodricks, and the KS Crump Group were
not acknowledged (Morford, 2003f, g, and h). EPA specifically mentioned
[[Page 30186]]
and responded to the occupational exposure limit recommendations from
Drs. Rozman, Doull, and Stelljes in the preamble to the June 2003 NPRM
at 68 FR 33298-33299. In addition, EPA included more detailed written
responses to these derivations and the evaluation by Dr. Rodricks in
the online docket prior to proposal (EPA-HQ-OAR-2002-0064-0017, -0018,
and -0019). We considered these documents in preparation of the June
2003 proposal as well as this proposal.
In general, we disagree that the neurotoxicity endpoint selected by
Drs. Rozman and Doull is the most appropriate endpoint for setting an
AEL and we agree with Dr. Stelljes that sperm motility in the F1
offspring generation of the WIL, 2001 2-generation study is an
appropriate endpoint. We agree with a number of these documents that
data from the F1 generation may be conservative because workplace
exposure would not include exposure to the F1 animals during the four-
week period from weaning to sexual maturity. However, EPA believes that
because of the potential for in utero effects that would only be seen
in the offspring generation, looking only at the F0 parental generation
could underestimate the adverse health impacts of a chemical.
Therefore, it was appropriate for us to consider effects seen in both
the F0 parental generation and the F1 offspring generation. Further,
effects on sperm motility in the parental and offspring generations are
seen at levels generally consistent with multiple reproductive effects
seen in both generations and both sexes exposed to nPB, such as estrous
cycle length, lack of estrous cycling, the number of estrous cycles in
a 3-week period, and the number of live pup births (TERA, 2004; ICF,
2006a; SLR International, 2001; Stelljes and Wood, 2004). We believe
that the document from the K. S. Crump group, a survey of the ratio of
points of departure to TLVs set by the ACGIH, is not relevant now that
the ACGIH has issued a TLV specifically for nPB. ACGIH appears to set
an AEL for nPB that is a factor of 10 lower than the endpoint cited as
lowest (100 ppm for effects on pup weight) (ACGIH, 2005). Thus, ACGIH
has used an approach for nPB consistent with the total uncertainty
factor of 10 assigned by EPA. In general, we find that these documents
submitted by the commenter assigned uncertainty factors in a manner
inconsistent with EPA guidance. This would result in a higher AEL than
we would determine following the approach EPA has used on other
chemicals, as well as an AEL that in our view would not sufficiently
protect human health from nPB's effects because of multiple sources of
uncertainty in available data (e.g., variability within the working
population, differences between animals and humans in how nPB affects
the reproductive system).
Since the 2003 NPRM, a number of reviews of nPB toxicity have been
issued, several of which include recommendations for occupational
exposure limits. CERHR, 2003a and 2004a are similar to CERHR, 2002a,
the expert panel report for nPB for the Center for the Evaluation of
Risks to Human Reproduction (CERHR). CERHR, 2003b and 2004b are similar
to CERHR, 2002b, the CERHR expert panel's report for iPB. These
documents discuss the usefulness of data in available studies for
assessing nPB's health impacts and establish No Observed Adverse
Concentration levels of 100 ppm for both male and female reproductive
effects in animals, but do not derive an AEL. Rozman and Doull, 2005
derived an AEL of 25 ppm for nPB based on neurotoxicity, using more
recent information than Rozman and Doull, 2002.
The Stelljes and Wood (2004) analysis is similar in its results to
SLR International (2001), a study by the same authors. EPA previously
reviewed SLR International, 2001 in developing the June 2003 NPRM. Both
studies by Stelljes and Wood concluded with a recommended AEL of 156
ppm, based on male reproductive effects and uncertainty factors of 1 in
driving the AEL. Stelljes (2005) reviews RTI's 2005 study on metabolism
of nPB in mice and rats and other literature and speculates that humans
should be less sensitive to nPB than either mice or rats based on
differences in metabolite production. Stelljes (2005) recommends that
no uncertainty factor is required to extrapolate from animals to humans
and that an uncertainty factor of no more than 2 is appropriate to
account for differences within the working population. All of these
documents assigned uncertainty factors in a manner that is not
sufficiently supported by the available data and that is inconsistent
with EPA's guidance. For example, Stelljes (2005) discusses metabolic
data in rats and mice from RTI, 2005 and concludes that on this basis,
the uncertainty factor for extrapolation from animals to humans should
be 1. However, the metabolic data relate to pharmacokinetics--the
activity of chemicals in the body--and do not address EPA's proposed
uncertainty factor of 3 related to pharmacodynamics (the biochemical
and physiological effects of chemicals in the body and the mechanism of
their actions). Using the AEL from one of these documents would result
in a higher, less protective AEL than we would determine following the
approach EPA has used for other chemicals under the SNAP program and
would not consider multiple sources of uncertainty in health effects
(i.e., variability within the working population and differences
between animals and humans in how nPB affects the reproductive system).
Thus, we are concerned that the AELs based on these documents would not
be sufficiently protective and would result in an inappropriate
acceptability decision. Detailed reviews of these documents are
available in the public docket.
Toxicological Excellence in Risk Assessment (TERA), 2004 reviews
other AEL derivations for nPB, performs a benchmark dose (BMD)
analysis, and recommends an AEL of 20 ppm based on live litter size.
This analysis is consistent with EPA guidance for BMD modeling and for
assigning uncertainty factors. A review of this document is available
in the public docket (ICF, 2004c).
ICF (2004b, 2006a) derived an AEL for nPB based upon female
reproductive effects. ICF (2004b, 2006a) discussed the relevant
literature (Ichihara et al., 1999, 2002, 2004a, 2004b; Sekiguchi, 2002;
Yamada et al., 2003; WIL, 2001) and calculated mean estrous cycle
length and the mean number of estrous cycles occurring during a three-
week period at different exposure levels in the WIL, 2001 2-generation
study. ICF (2004b, 2006a) found statistically significant reductions in
the number of estrous cycles in a three-week period, both including and
excluding females that had stopped their estrous cycles, at 250, 500,
and 750 ppm in the F0 parental generation and at 500 and 750 ppm in the
F1 generation. ICF (2004b, 2006a) conducted BMD modeling and calculated
BMDL values of the number of estrous cycles in a three-week period that
varied from 102 to 208 ppm, depending upon the model used and the
benchmark criteria selected. All data were calculated based on the mean
reductions in estrous cycle number calculated from the WIL, 2001 study.
Values were calculated for the F0 generation; the number of data for
the F1 generation was too small for statistical analysis. The BMDLs
that ICF calculated for the number of estrous cycles in a three-week
period were 162 ppm and 208 ppm, depending on the benchmark response
criteria (10% change in response vs. one standard
[[Page 30187]]
deviation) and using a linear-heterogeneous model.
The California Environmental Protection Agency's Office of
Environmental Health Hazard Assessment (OEHHA) listed both nPB and iPB
as reproductive toxins on the basis of developmental, male
reproductive, and female reproductive toxicity under the State's Safe
Drinking Water and Toxic Enforcement Act of 1986, also known as
Proposition 65 (OEHHA, 2006). Under this law, California is required to
list chemicals known to be carcinogenic or to be reproductive toxins
and to update that list at least annually.
The American Conference of Government Industrial Hygienists (ACGIH)
issued a recommended Threshold Limit ValueTM (TLV) of 10 ppm
(time-weighted average) for nPB (ACGIH, 2005). ACGIH summarized
numerous studies showing different effects of nPB and identified no
observed effect levels (NOELs) of 200 ppm for hepatotoxicity
(ClinTrials, 1997b) and less than 100 ppm for developmental toxicity,
as evidenced by decreased fetal weight (Huntingdon Life Sciences,
2001).
OSHA has not developed a permissible exposure limit (PEL) for nPB
that EPA could use to evaluate toxicity risks \17\ from workplace
exposure. In prior SNAP reviews, EPA has used ACGIH TLVs where
available in assessing a chemical's risks and determining its
acceptability if OSHA has not set a PEL. ACGIH is recognized as an
independent, scientifically knowledgeable organization with expertise
in issues of toxicity and industrial hygiene. However, in this case,
EPA believes that ACGIH's TLV for nPB of 10 ppm has significant
limitations as a reliable basis for an acceptable exposure limit,
especially given the availability of other, more comprehensive analyses
described in this proposal. First, according to the authors of the
Huntingdon Life Sciences study, the decrease in fetal weight was an
artifact of sampling procedure that biased the data (test animals were
only sacrificed at the end of the day rather than at random). The CERHR
expert panel excluded ``aberrantly low'' fetal weights from one litter
in this study and calculated a BMDL greater than 300 ppm for this
endpoint after removing those outlier data (CERHR, 2002a, 2003a, and
2004a). TERA calculated a similar BMDL when analyzing the same data set
(TERA, 2004). Further, the reference list in the documentation on the
TLV indicates that ACGIH did not review and evaluate all the studies
available prior to the development of the recommended exposure limit.
For example, key supporting articles that reported disruption of
estrous cycles (Yamada et al., 2003 and Sekiguchi et al., 2002) were
not discussed in the TLV documentation. Further, ACGIH did not provide
sufficient reasoning for the selection of the chosen endpoint over
others (e.g., reproductive toxicity and/or neurotoxicity). The lack of
discussion of applied uncertainty factors also prevents a determination
of how ACGIH arrived at a TLV of 10 ppm. In summary, EPA is not basing
its proposed acceptability determination for nPB on the ACGIH TLV
because: (1) Other scientists evaluating the database for nPB did not
find the reduced pup weight to be the most sensitive endpoint; (2)
benchmark dose (BMD) analysis of the reduced pup weight data (CERHR,
2002a; TERA, 2004) results in a higher BMDL (roughly 300 ppm) than
those for reproductive effects; and (3) ACGIH may not have reviewed the
complete body of literature as several studies discussing neurotoxicity
and female reproductive effects were omitted from the list of
references. A number of reviews of this document are available in the
public docket (ICF, 2004d; O'Malley, 2004).
---------------------------------------------------------------------------
\17\ Vendors of nPB-based products have recommended a wide range
of exposure limits, from 5 ppm to 100 ppm (Albemarle, 2003;
Chemtura, 2006; Docket A-2001-07, item II-D-19; Enviro Tech
International, 2006; Farr, 2003; Great Lakes Chemical Company,
2001).
---------------------------------------------------------------------------
We note that, even if EPA had selected the ACGIH TLV as our basis
for assessing the risks of nPB, we would have proposed the same
determinations. In the specific coatings application that we propose to
find acceptable subject to use conditions at the Lake City Army
Ammunition Plant, exposure data showed an ability to meet an exposure
level of 10 ppm, with the vast majority of measurements below that
value. Thirty-four of 35 samples had concentrations below 10 ppm, and
the mean concentration for the plant was less than 4 ppm (Lake City
Army Ammunition Plant, 2004). For the aerosol and adhesive end uses, it
would be even more difficult to achieve an exposure level of 10 ppm
than to achieve a level in the range that EPA is considering (17 to 30
ppm). Thus, we would have proposed the same decisions for nPB of
acceptable, subject to use conditions for coatings and unacceptable for
aerosols and adhesives using the ACGIH's TLV of 10 ppm to assess health
risks. Despite some flaws in its derivation, the TLV of 10 ppm is less
than two-fold lower than the low end of the range of acceptable
exposure levels based on the most sensitive reproductive endpoints.
This small difference is well within the uncertainty required to
extrapolate a benchmark dose from an experimental study in rats to an
occupational exposure limit in humans.
E. Community Exposure Guideline
In this proposal, EPA is using a community exposure guideline (CEG)
of 1 ppm to evaluate potential health risks among populations living
near facilities using nPB. This community exposure guideline is an
estimate of a continuous inhalation exposure (averaged over 24 hours
per day, 7 days per week) to the general public (including sensitive
subgroups) that is likely to be without an appreciable risk of adverse
health effects during a lifetime.
Based on EPA risk assessment guidelines (US EPA, 1994b), the CEG
was derived using the lowest BMDL from effects listed in Table 6 as the
point of departure (110 ppm for vacuolation in the liver of animals in
the F1 generation of WIL, 2001). The HEC was calculated as follows:
110 ppm x (6 hours exposure in study/24 hours avg time) x (7 days/7
days) = 28 ppm
EPA used an uncertainty factor of 3 for extrapolation from animals
to humans, as discussed above in section VI.A, and an uncertainty
factor of 10 for variability within the general population, consistent
with EPA's RfC guidelines. Dividing the HEC of 28 ppm by 30 yields a
community exposure guideline of approximately 1 ppm. If we had used
sperm motility (HEC of 42 ppm based on a BMDL of 169 ppm) or number of
estrous cycles (HEC of 40 ppm based on a BMDL of 162 ppm) as starting
points, we would calculate the same approximate CEG value. We note
that, following RfC guidelines, EPA's community exposure guideline
includes a number of conservative assumptions, including exposure
adjustments to protect an individual exposed for up to 24 hours a day
for 70 years (U.S. EPA, 1994b, p. 1-5).
EPA evaluated general population exposure using EPA's SCREEN3 (U.S.
EPA, 1995b) air dispersion model to assess the likely maximum
concentration of nPB from single sources.\18\ EPA used data collected
from
[[Page 30188]]
actual facilities (Swanson, 2002) to characterize two scenarios: (1) A
typical large, high-use adhesive application facility where the closest
resident is 100 meters away; and (2) a smaller facility with average-
use adhesive application in an urban area, where the nearest resident
is only 3 meters away. The results indicated that modeled exposures in
either scenario did not exceed the CEG of 1 ppm. The highest exposure
modeled was 0.24 ppm at a distance of 3 meters away from the source in
the urban scenario, while most other exposures were at least an order
of magnitude lower (ICF, 2003; ICF, 2006a). Because the community
exposure guideline was not exceeded for any of the exposure scenarios
in this conservative screening approach, EPA has concluded that nPB
exposure to populations living close to facilities using nPB is not a
concern for purposes of determining the acceptability of nPB under the
SNAP program.
---------------------------------------------------------------------------
\18\ We performed the modeling for a facility using nPB-based
adhesives because the nPB emissions from this type of facility were
expected to be higher than those from facilities using nPB for other
end uses. Thus, if a facility using adhesives would not result in
emissions exceeding the CEG, facilities using nPB in aerosols or in
metals, electronics, or precision cleaning also would not result in
emissions exceeding the CEG.
---------------------------------------------------------------------------
VI. What listing is EPA proposing for each end use, and why?
In this rule, EPA is proposing to find nPB unacceptable in adhesive
and aerosol solvent end uses, and acceptable subject to use conditions
in the coatings end use. The proposed listings, summarized in Table 9,
are intended to allow the use of nPB where it does not pose a human
health risk significantly greater than other substitutes and prohibit
nPB's use where nPB exposure cannot be maintained, or is unlikely to be
maintained, at even the highest level considered in this proposal
(i.e., 30 ppm). We also are taking comment on an alternate approach of
finding nPB acceptable subject to use conditions in the above end uses
(see Section VII.A).
Table 9.--Proposed Decisions by End Use and Sector
------------------------------------------------------------------------
And our proposed
For nPB in this sector and Our proposal is to alternate approach
end use: list nPB as: is:
------------------------------------------------------------------------
Aerosols:
Aerosol solvents........ Unacceptable........ Acceptable, subject
to use
conditions.\2\
Adhesives, Coatings, and
Inks:
Coatings................ Acceptable, subject Acceptable, subject
to use conditions to use
\1\. conditions.\2\
Adhesives............... Unacceptable........ Acceptable, subject
to use
conditions.\2\
------------------------------------------------------------------------
\1\ Use of nPB in this end use is limited to coatings at facilities
that, as of May 30, 2007, have provided EPA information demonstrating
their ability to maintain acceptable workplace exposures (i.e., the
Lake City Army Ammunition Plant).
\2\ Use conditions would include proposed requirements that users must
(1) meet an exposure limit of 20 ppm on an eight-hour time-weighted
average, (2) monitor workers' exposure to nPB using a personal
breathing zone sampler on an eight-hour time-weighted average
initially and periodically (every 6 months or longer, depending on the
concentration during initial monitoring), and (3) keep records of the
worker exposure data on site at the facility for at least three years
from the date of the measurement.
A. Aerosol Solvents
In this rule, EPA proposes to find nPB unacceptable in the aerosol
solvent end use. There are a number of aerosol solvent alternatives
that do not pose any risk for ozone depletion or for ground level smog
formation.\19\ EPA's greatest concern with nPB-based aerosols is that
users of nPB as an aerosol solvent cannot reliably maintain exposures
at sufficiently low levels to ensure that workers are protected. This
finding is based on measured exposure data and model estimations
indicating the likelihood of elevated concentrations associated with
nPB-based aerosols given typical ventilation conditions. A number of
other acceptable solvent alternatives are available that can be used at
exposure levels below their respective acceptable exposure limits.
---------------------------------------------------------------------------
\19\ Smog, also known as ground-level ozone, is produced from
emissions of volatile organic compounds that react under certain
conditions of temperature and light.
---------------------------------------------------------------------------
Ventilation conditions are an important consideration in evaluating
potential risks within this end-use category. ``Benchtop cleaning'' of
individual parts, which is feasible under exhaust hoods or in spray
booths with adequate ventilation, comprises 25% or less of the market
involving ODS substitutes for aerosols (U.S. EPA, 2004). According to
industry information and several commenters, the majority of the market
for nPB-based aerosols involves in-place applications requiring a
portable aerosol, such as cleaning energized electrical contacts and
switches, maintenance in underground mines, or cleaning active elevator
motors (CSMA, 1998; U.S. EPA, 2004; Williams, 2005). These applications
often occur in tightly confined spaces where it is not feasible to
install ventilation equipment or remove parts to ventilated areas
(CSMA, 1998; Linnell, 2003; Werner, 2003). Other acceptable
substitutes, such as blends of HFEs or HFCs and trans-dichloroethylene,
are available in these end uses. One commenter also suggested that a
user of an nPB-based aerosol will assume that they are being provided
with a product that offers similar margins of safety as the product
being replaced (i.e., HCFC-141b) and therefore can be used under the
same conditions (Werner, 2003).
The likelihood that nPB aerosol solvents would be used in poorly
ventilated spaces is of particular concern given the likelihood of
elevated exposure levels. The exposure data from aerosol solvent use
are extremely limited. These data are from simulations of a number of
situations where nPB might be used, such as benchtop cleaning of
electronics and cleaning automotive brakes, rather than data from
facilities currently using nPB in manufacturing or maintenance
processes. Thus, the available exposure data may not be representative
of ventilation levels normally used with nPB-based aerosols and may not
adequately represent exposure levels during in-place cleaning,
industry's most common application for nPB-based aerosols. The
distribution of exposure levels in the seven samples ranging from 5.5
to 32 ppm corresponded to the range of ventilation rates reported--0,
300, 640, and 1900 cfm--with the highest ventilation rate resulting in
the lowest exposure levels and the lower ventilation levels resulting
in the values above 30 ppm. The ventilation rate most consistent with
use in a confined space for in-place cleaning, 0 cfm, resulted in half
the exposures (one of two) exceeding 30 ppm. The highest ventilation
rate, 1900 cfm, occurred at a vented booth, which would not be feasible
to install for in-place cleaning applications--the majority of
applications for nPB-based aerosols. The middle ventilation rates of
300 and 640 cfm occurred during use of a fan for an entire room
(regional ventilation), as might be expected for benchtop cleaning
(Confidential submission, 1998), but not for in-place cleaning in
confined spaces. In modeling nPB exposure from aerosol solvent use at a
low ventilation rate of
[[Page 30189]]
450 cfm, a level that might be expected during benchtop cleaning, 8-
hour average concentrations of 16.5 to 33 ppm are predicted, depending
on the amount of nPB used (ICF, 2006a). Exposure levels for confined
spaces with even lower ventilation rates, as we would expect for in-
place cleaning, would be even higher, likely exceeding the high end of
the range that EPA is considering. Short-term exposures of 370 and
1,100 ppm taken from workers' collars in a room with regional
ventilation at 640 cfm, when averaged over an 8-hour period, resulted
in exposure levels of 12 and 34 ppm. These exposures occurred as a
result of using nPB over a period up to 15 minutes, so it is likely
that users would have greater exposure than 30 ppm if they used nPB for
longer than 15 minutes per day, as with multiple uses. The available
data sets have a small sample size, may not be representative of in-
place cleaning in confined spaces, and do not provide EPA with
convincing data that nPB is likely be used safely, at exposure levels
at or below the highest level in the range we are considering for
evaluation of acceptability.
EPA is concerned that many, and perhaps most, uses of nPB aerosol
solvents result in a high probability of exposures at or above even the
upper end of the range of exposures that the Agency is considering to
be potentially acceptable. EPA is aware of no data on ventilation
levels demonstrating that most users of aerosol solvents, or of nPB in
particular, would use aerosols in locations with sufficiently high
ventilation levels to protect human health (e.g., 1900 cfm or greater).
We request data on worker exposure levels, typical ventilation rates,
and patterns for usage of nPB-based aerosols, considering both benchtop
and in-place use.
EPA has found numerous other aerosol solvents acceptable. These
aerosol solvents can be used safely in a manner consistent with their
respective acceptable exposure limits. This is highlighted in a study
comparing concentrations of eight different chemicals that are
acceptable under the SNAP program in aerosol formulations: HFE-7100,
HFE-7200, trans-1,2-dichloroethylene, HCFC-225ca and -225cb, acetone,
pentane, and HFC-134a. In this study, with ventilation of only 48 cfm,
8-hr TWA exposure from the different chemicals varied from 35.5 ppm to
194.0 ppm, and all chemicals met their respective recommended exposure
levels (ICF, 2006a). As discussed above in section V.A, when these
concentrations are adjusted for the chemicals' respective molecular
weights, they would correspond to nPB concentrations of 29.5 to 394.4
ppm, which is at or above even the highest level the Agency would
consider acceptable. The ventilation level in this study is closer to
what we would expect in a confined space where fans or vents cannot be
installed, as for in-place cleaning. Based on these considerations, the
Agency believes that nPB used as an aerosol solvent would impose
significantly more risk to human health than other alternatives
available for this end use.
B. Adhesives
EPA proposes to find nPB unacceptable in the adhesive end use. As
for aerosol solvents, we found that some alternative adhesive
formulations could reduce particular environmental risks more than nPB,
such as generation of ground level ``smog'' or ozone depletion
potential. However, we find the greatest concern in this end use is
with nPB's human health effects. We propose to find nPB unacceptable in
adhesives because it poses significantly greater risk to human health
as compared to other available alternatives in this end use.
In the June 2003 NPRM, we initially proposed to find nPB acceptable
in adhesives based on the SNAP program principle that ``EPA does not
intend to restrict a substitute if it poses only marginally greater
risk than another substitute * * *. The Agency also does not want to
intercede in the market's choice of available substitutes, unless a
substitute has been proposed or is being used that is clearly more
harmful to human health and the environment than other alternatives.''
(68 FR 33294, citing the original March 18, 1994 SNAP rule at 59 FR
13046). At the time of the proposal, we considered data from NIOSH
monitoring and health hazard evaluations for three facilities using
nPB-based adhesives. At two of the three facilities, NIOSH worked
together with the companies to install state-of-the-art ventilation
equipment. Looking at exposure data from all workers after ventilation
improvements, we believed it would be possible for facilities to meet
the proposed AEL of 25 ppm (68 FR 33294).
One public commenter suggested that EPA should reconsider
whether industrial exposures consistently occur and/or can be
controlled to a level at or below 25 ppm (Werner, 2003). We reevaluated
the exposure data for the two plants that had improved their
ventilation, focusing on exposure to the workers that receive the
highest exposures because they directly spray the nPB-based adhesive.
We found that, even in the best case, a substantial number of workers
spraying nPB-based adhesives would be exposed above the highest level
in the range we are considering.
NIOSH investigators initially reported that mean exposures
to nPB ranged from 60 to 381 ppm (8-hour time weighted averages) at
three different foam-fabrication facilities using nPB-based adhesives
(NIOSH, 2000a, 2000b, 2001, 2002a, 2002b, 2003a). In one facility,
average (mean) nPB exposures were reduced from 169 ppm to 19 ppm,
following installation of ventilation equipment (NIOSH, 2000b).
Although use of spray booths at this facility reduced the average
exposure level to 19.4 ppm for all workers, the majority of the
sprayers directly using nPB-based adhesives still would be exposed at
unacceptably high levels. Out of fourteen sprayers at the Custom
Products facility:
Six, or 43% of sprayers, would be exposed to more than 30
ppm.
Nine, or 64% of sprayers, would be exposed to more than 25
ppm.
Ten, or 71% of sprayers, would be exposed to more than 20
ppm.
Eleven, or 79% of sprayers, would be exposed to more than
15 ppm.
Thirteen, or 93% of sprayers, would be exposed to more
than 10 ppm.
At another facility using nPB-based adhesives, the average exposure
was reduced from 58 pm to 19 ppm after the company installed
ventilation recommended by NIOSH (NIOSH, 2001). Data on exposure for
sprayers found fewer individuals receiving high exposures than at the
facility monitored in NIOSH (2000b), but 65% (22 of 34) of exposure
samples for sprayers were higher than 15 ppm, 33% (11 of 34) were
higher than 20 ppm and 15% (5 of 34) were higher than 25 ppm after
improving ventilation.
Overall, 42% of sprayers in these two facilities using nPB-based
adhesives were exposed to concentrations of nPB greater than 20 ppm (21
of 48 workers) and 23% (14 of 48 workers) were exposed to more than 25
ppm, even after installing state-of-the-art ventilation with assistance
from NIOSH. Sprayers had significantly higher individual exposures than
workers who did not work directly with the nPB-based adhesive.
In response to public comment and additional information available
to EPA since the June 2003 NPRM, we now propose that use of nPB-based
adhesives poses significantly higher risks to human health than other
available adhesives. Since the June 2003 NPRM, there have been a number
of reports of
[[Page 30190]]
workers working with nPB-based adhesives that have suffered adverse,
persistent neurological effects that resulted in hospitalization (Beck
and Caravati, 2003, and Majersik et al., 2004, 2005; Calhoun County,
2005; Miller, 2005; Raymond and Ford, 2005). Based on data from actual
facilities using adhesives, it is estimated that a facility using nPB
with average adhesive application rates and average ventilation rates
would have exposure levels of approximately 60 ppm on an 8-hr time-
weighted average (ICF, 2006a). Modeling of exposures at high adhesive
application rates and average or lower ventilation rates resulted in
exposures of approximately 250 to 2530 ppm (ICF, 2006a). We believe
these modeling results show that most adhesive users would exceed
acceptable exposure levels by significant margins and that it is
unlikely that adhesive users would be able to use nPB safely.
Considering the exposure data for nPB-based adhesives, we believe
it is unlikely that, even with improved ventilation, adhesive users
could reduce exposures to acceptable levels on a consistent basis. In
the best case seen, a facility with low to average initial exposure
levels was able to reduce exposures to the middle of the range EPA is
considering after extensive assistance from NIOSH in installing state-
of-the-art ventilation. We expect that many facilities will begin with
higher exposure levels and will not have the same level of assistance
to improve ventilation, thus making it unlikely that they would achieve
acceptable exposures. Given the information above, we are concerned
that nPB-based adhesives cannot be reliably used in a manner that
protects human health. We request comment and further data on whether
it is feasible to use nPB-based adhesives with worker exposure levels
consistently at or below any of the values in the range of exposure
levels that EPA is considering potentially acceptable (i.e., 17 to 30
ppm).
The available information indicates that all acceptable carrier
solvents in adhesives other than nPB have projected or actual exposure
less than the appropriate workplace exposure limit EPA used in finding
those substitutes acceptable. Examples of other carrier solvents
currently used in adhesives and acceptable under the SNAP Program
include hydrocarbon solvents, acetone, methylene chloride, and water.
EPA finds that there are other available alternatives that pose
significantly less risk to human health and the environment compared to
nPB in the adhesives end use.
During the public comment period on the June 2003 NPRM, one
commenter representing the adhesives industry stated that there are
some small but critical applications that require nonflammability and
high solvency (Collatz, 2003). The commenter did not specify what those
applications are, and whether there was information showing that other
types of adhesives, such as those using water, flammable solvents, or
methylene chloride, are technically infeasible in these applications.
We request comment and data on whether there are any unique
applications in the adhesives end use for which there are no
technically feasible alternatives other than nPB and thus, for which
nPB should be allowed. If so, and if determined that nPB should be
unacceptable except where no other substitutes are feasible, we would
consider finding nPB acceptable subject to narrowed use limits, with
requirements for each end user to perform a demonstration that there
are no other technically feasible alternatives for their particular
site, to install local exhaust ventilation equipment designed to reduce
exposures to acceptable levels and to perform worker exposure
monitoring. Alternatively, if there was sufficient information provided
during the public comment period showing that there are applications in
which nPB can be safely used, we would consider finding nPB acceptable
in adhesives, subject to use conditions requiring installation of local
exhaust ventilation and worker exposure monitoring. This would allow
for use of nPB in any applications where it may be used safely if any
such applications exist.
C. Coatings
We are proposing to find nPB acceptable, subject to use conditions,
for facilities that, as of May 30, 2007, have provided EPA information
demonstrating their ability to maintain workplace exposure levels below
even the minimum level of the range of exposures that EPA is
considering to be potentially acceptable (i.e., 17 to 30 ppm). The SNAP
submission with information on coatings was made for a single facility
and EPA is unaware of anyone else interested in using nPB in this end
use. Therefore, there are currently no analyses indicating whether nPB
would pose significantly greater risks in any coating applications
other than this facility. Workplace exposure levels to nPB from
ammunition sealant at Lake City Army Ammunition Plant ranged from less
than 1 ppm up to 21 ppm on an eight-hour time-weighted average. Thirty-
four of 35 samples had concentrations below 10 ppm, and the mean
concentration for the plant was less than 4 ppm (Lake City Army
Ammunition Plant, 2004). The vast majority of measurements show worker
exposure well below the lowest level in the range of exposures that EPA
is considering. Thus, we believe that nPB can be used as safely as
other acceptable solvents used at their acceptable exposure limits
under the conditions at this facility.
Other acceptable substitutes for ozone-depleting substances in
coatings, in general, include oxygenated solvents, hydrocarbon
solvents, terpenes, hydrofluoroethers 7100 and 7200, benzotrifluorides
(include parachlorobenzotrifluoride), monochlorotoluenes, trans-1,2-
dichloroethylene, chlorinated solvents, water-based formulations, and
high-solids formulations. In the particular application for ammunition
coatings, the submitter evaluated a large number of alternatives and
found that n-propyl bromide was the only one of 29 solvents tested that
could meet performance specifications at this facility (Harper, 2005).
Thus, it is not clear that there are other substitutes available for
this specific application, and exposure data show that in this specific
application, nPB can be used in a way that does not pose significantly
greater risks to human health compared to other acceptable substitutes
in the coatings end use.
VII. What other regulatory options did EPA consider?
EPA considered several different options, but we prefer the
approach proposed in this rule. We also take comment on the options
discussed below.
A. Alternate Option for Comment: Acceptable With Use Conditions
Requiring Exposure Limit and Monitoring
We also take comment on a proposed alternate approach in which nPB
would be acceptable subject to use conditions in all the end uses
addressed in this action. Under this alternate approach, users would
meet an exposure limit, monitor exposure of workers using nPB, and keep
records to demonstrate compliance with these requirements. For purposes
of this alternative proposal, we selected 20 ppm to use as an exposure
limit above which use would be unacceptable, and 10 ppm as an action
level that allows reduced exposure monitoring, for the reasons
discussed below in section VII.A.1, ``Use Conditions and Their
Rationale.'' However, we are soliciting comment on whether a different
exposure level within the 17 to 30 ppm range should
[[Page 30191]]
be selected. The following requirements would apply at each facility
where nPB is used:
Exposure Limit
The owner or operator would be required to ensure that workers
using nPB are exposed to no more than 20 ppm on an 8-hour time-weighted
average. The exposure limit could be met through engineering controls
(e.g., ventilation equipment), work practices, or reduced use of nPB.
Initial Worker Exposure Monitoring
For each facility where nPB is used, the owner or operator of the
facility would be required to ensure that personal breathing zone air
samples of each nPB user's exposure would be collected on an eight-
hour, time-weighted average initially within 90 days after a final rule
becomes effective. Monitoring measurements may be taken with an organic
chemical monitoring badge on the collar or a tube filled with charcoal
on the collar.
Periodic Exposure Monitoring
(1) The owner or operator of the facility would be required to
ensure that personal breathing zone air samples of user exposure are
collected periodically on an eight-hour, time-weighted average
depending on the results of the most recent set of exposure data. A
monitoring program could be instituted by the company or by the nPB
supplier for that facility. Periodic sampling requirements would be
based on the most recent monitoring results, as follows:
Table 10.--Alternative Approach Exposure Levels and Periodic Exposure
Monitoring
------------------------------------------------------------------------
If exposure measurements for nPB are at
this level: Then the owner or operator:
------------------------------------------------------------------------
all measurements at or below 10 ppm.... is not required to perform
periodic exposure monitoring.
all measurements at or below 20 ppm, must take personal breathing
with some measurements above 10 ppm. zone samples again at least
once in the next six months.
at least one measurement above 20 ppm.. must stop using nPB in the
application exceeding the
exposure limit until exposure
data show that 20 ppm can be
consistently met in the vast
majority of cases.
unknown, in cases of new workplace must take personal breathing
conditions increasing exposure or new zone samples as a test before
applications of nPB. using nPB in new industrial
applications or conditions, or
within 7 days of an emergency
caused by a leak, rupture or
breakdown, and use this value
to determine the next time
monitoring is required.
------------------------------------------------------------------------
(2) For periodic monitoring, the owner or operator would be allowed
either to monitor each nPB user's exposure, or to monitor exposure of a
representative nPB user in each job classification in a work area
during every work shift, where the monitored nPB user is expected to
have the highest exposure.
(3) The owner or operator would be allowed to discontinue the
periodic 8-hour TWA monitoring for nPB users at the facility where at
least two consecutive sets of measurements taken at least seven days
apart are below 10 ppm.
Monitoring for New Conditions or Applications
Whenever there is a change in workplace conditions that may
increase exposure or whenever a new application of nPB is introduced,
the owner or operator would be required to take personal breathing zone
samples accounting for all nPB users as a test before using nPB in
manufacturing or repair. These could be either samples for each nPB
user or samples representing each job classification in a work area
during a work shift, so long as the samples are based on the user with
the likely highest exposure. Examples of changes in workplace
conditions that may increase exposure include changes in production,
process control equipment, or work practices, or a leak, rupture, or
other breakdown.\20\ Examples of introduction of a new application of
nPB include aerosol contact cleaning in a location with regional
ventilation or natural ventilation, where previous measurements were
carried out on workers in a location with local ventilation. If the
change occurs because of an unpredictable emergency, then the owner or
operator would need to ensure exposure monitoring takes place within 7
days of the change.
---------------------------------------------------------------------------
\20\ See 29 CFR 1910.1052(d)(4)(i).
---------------------------------------------------------------------------
Sampling Methods and Accuracy
Exposure samples would be required to be analyzed either by NIOSH
method 1003 for halogenated hydrocarbons or method 1025 for 1-
bromopropane and 2-bromopropane or by another method that is accurate
to 25% at the 95 percent confidence level.
Recordkeeping Requirements
The owner or operator of the facility would be required to keep
records of the monitored exposure data at the facility for at least
three years from the date the measurements were taken for purposes of
this rule. These records would be required to be made available in the
event of a facility inspection or a request for the data by EPA. Note
that the EPA's recordkeeping requirement does not affect OSHA's
standard on access to employee exposure and medical records, which
requires retaining any exposure records for at least 30 years (29 CFR
1910.1020(d)(ii)).
The regulatory listings by end-use under this alternate approach
that the Agency requests comment on would be as follows:
BILLING CODE 6560-50-P
[[Page 30192]]
[GRAPHIC] [TIFF OMITTED] TP30MY07.000
[[Page 30193]]
[GRAPHIC] [TIFF OMITTED] TP30MY07.001
BILLING CODE 6560-50-C
[[Page 30194]]
1. Use Conditions and Their Rationale
The major provisions of the use conditions and the related issues
that EPA considered in developing the alternate approach that we are
taking comment on are as follows:
Exposure limit. A requirement to meet a workplace exposure limit
would be an interim measure to ensure that nPB will be used safely
until OSHA issues a final permissible exposure limit (PEL) under the
Occupational Safety and Health Act. In the event that OSHA issues a
final PEL, it would supersede EPA's exposure limit. EPA is specifically
deferring to OSHA, and has no intention to assume responsibility to
displace OSHA's authority under Public Law 91-596. EPA's exposure limit
would not pre-empt the authority of OSHA to take regulatory or
enforcement action with respect to exposure to this substance. This is
made clear by the Clean Air Act under which EPA would promulgate this
regulation (Subchapter VI--Stratospheric Ozone Protection), which
provides at 42 U.S.C. 7610 in pertinent part: ``* * * this chapter
[Chapter 85--Air Pollution Prevention] shall not be construed as
superseding or limiting the authorities, under any other provision of
law, of the Administrator or any other Federal officer, department, or
agency.'' By issuing an exposure limit for nPB, EPA's intention would
be to fill existing regulatory gaps during the interim period of
substitution away from ozone-depleting compounds and provide the needed
margin of protection for human health and the environment until OSHA
develops other regulatory controls or standards under appropriate
authorities.
As discussed above in section IV.E.1, EPA is considering exposures
within the range of 17 to 30 ppm as potentially acceptable in order to
determine whether nPB may be used safely in each end use. For purposes
of having a clear compliance target under this alternative approach for
public comment, we are using 20 ppm as the exposure limit above which
use would be unacceptable. We chose this value because we expect it to
be protective against the reproductive and developmental effects
identified previously (live litter size, sperm motility, estrous
cycles). Worker exposure monitoring. The worker exposure monitoring
requirements under the use conditions in the alternate approach were
modeled after OSHA's requirements for monitoring for methylene
chloride. 29 CFR 1910.1052(d). We expect that the regulated community
would be familiar with this approach and there might be fewer changes
for regulated businesses if OSHA later were to establish a workplace
standard for nPB. Because the exposure limit would be an 8-hr TWA value
that is derived from studies that measured exposure via inhalation, the
proposed use conditions require the owner or operator to monitor 8-hr
TWA values that measure workers' exposure in the breathing zone (e.g.,
samples from a worker's collar). We are not proposing to monitor short-
term exposures because acute, short-term exposures of nPB are not of
significant health concern, so long as long-term exposures are below
the 8-hour TWA limit or potentially acceptable exposure levels (ERG,
2004).
Option for monitoring representative set of workers. Personal
breath zone samples could be taken either from each worker using nPB or
from a representative \21\ set of exposed workers expected to have the
highest exposure. Allowing exposure monitoring from representative
workers using nPB, rather than requiring separate monitoring for each
individual using nPB, would reduce overall compliance burden, while
still detecting any exposure levels in excess of the exposure limit and
avoiding underestimates of exposure.
---------------------------------------------------------------------------
\21\ In its methylene chloride standard, OSHA defined
representative sampling as follows: ``The employer has taken one or
more personal breathing zone air samples for at least one employee
in each job classification in a work area during every work shift,
and the employee sampled is expected to have the highest * * *
exposure.'' (29 CFR 1910.1052(d)(1)(ii)(A)).
---------------------------------------------------------------------------
Initial monitoring. Users already using nPB would need to undergo
exposure monitoring no later than 90 days after the date the final rule
becomes effective. A user that has never used nPB before would need to
perform initial monitoring before beginning to use nPB in the
facility's industrial applications.
Periodic monitoring. Monitoring would have to be performed
periodically on a schedule based on the results of the most recent set
of exposure monitoring data. Monitoring from workers' personal
breathing zone would be required during the next six months if an
initial measurement finds exposure levels between the action level \22\
and the 8-hour TWA exposure limit. No periodic monitoring would be
required if initial measurements are below the action level. The action
level would be the value that is half the exposure limit, in this case
10 ppm. OSHA standards also set an action level of half the PEL.
---------------------------------------------------------------------------
\22\ The action level is the exposure level that is half the 8-
hour TWA exposure limit. In this case, the action level would be10
ppm.
---------------------------------------------------------------------------
Under the alternate approach, monitoring would no longer be
required where the most recent exposure monitoring data found all
worker exposures at or below 10 ppm. OSHA rules also reduce monitoring
requirements for exposures below the action level because if measured
values are that low, it is unlikely that any measurement will exceed
the PEL unless a major change to the process occurs.
Monitoring for changes in workplace conditions or nPB use. New
monitoring would be required if an event occurs that would make the
most recent set of monitoring data no longer representative. EPA would
expect that the owner or operator would plan new applications of nPB or
changes to control equipment or work practices and would perform a test
for worker exposure levels before using nPB on a regular basis in that
application. In the case of an emergency, such as a breakdown of
ventilation equipment or a leak, we would expect exposure monitoring to
be performed as soon as possible, and no later than 7 days after the
change in workplace conditions. This period is intended to give an
owner or operator time to locate and purchase exposure monitoring
equipment in an emergency where the equipment may not already be
available at the facility.
Monitoring method and accuracy. We take comment on the use of NIOSH
methods 1003 and 1025 (NIOSH, 2003b and c) for analyzing nPB exposure
under the proposed alternate approach. Several of the studies that
supplied EPA with exposure data used this method and they are
standardized methods prepared by NIOSH, a recognized authority on
industrial hygiene. In addition, we would allow other methods that are
accurate to 25% at the 95 percent confidence level. Based
on the accuracy of available methods, most OSHA standards require
exposure monitoring accurate to 25% at the 95 percent confidence level,
as in the methylene chloride standard (29 CFR 1910.1052(d)(1)(iii)(A))
and other OSHA standards.
Recordkeeping requirements. We would require that users keep
records of the worker exposure data for three years from the date the
measurement is taken.\23\ This would provide information allowing EPA
to determine if facilities are complying with the exposure limit and if
workers exposed to nPB are sufficiently protected.
---------------------------------------------------------------------------
\23\ OSHA's standard on access to employee exposure and medical
records requires retaining exposure records for at least 30 years
(29 CFR 1910.1020(d)(ii)), and these requirements would not be
affected by this regulation.
---------------------------------------------------------------------------
Responsibility for meeting requirements. Under the alternate
approach, the owner or operator of a
[[Page 30195]]
facility using nPB would be responsible for meeting the rule's use
conditions.
2. Advantages and Disadvantages of the Alternate Approach
Setting use conditions that require users to meet an exposure limit
and to monitor and keep records to demonstrate achieving the limit
would protect the health of nPB users while giving industry more
flexibility and more options for ODS substitutes, compared to finding
nPB unacceptable. This could be especially useful for users of HCFC-
141b as an aerosol solvent that are seeking an effective ODS
substitute. If there were any situations in which other available
alternatives did not provide as good performance, nPB would still be
available as an option, provided the use conditions could be met. The
monitoring requirements would encourage good industrial hygiene and
safe use of nPB.
Considering the list of use conditions above, we believe that
setting use conditions requiring an exposure limit, worker exposure
monitoring, and recordkeeping would be complex and potentially
confusing. Requiring users to meet the exposure limit, although
providing greater potential flexibility, also would provide less
certainty about how to comply. A user could spend considerable time and
expense trying to meet the exposure limit, only to find that it is not
achievable.
Given the limited circumstances under which we expect aerosol and
adhesive users could meet an acceptable exposure limit and given the
availability of other, less toxic alternatives in both of these end
uses, EPA's preferred option is to find nPB unacceptable in aerosols
and adhesives. Further, considering that without regulatory
requirements, the users of nPB at the Lake City Army Ammunition Plant
have been operating with the vast majority of exposure levels below 17
ppm, the low end of the range of exposures that EPA is considering to
be potentially acceptable (Lake City Army Ammunition Plant, 2004), it
appears unnecessary to require an exposure limit in that application.
B. Regulatory Options Where nPB Would Be Acceptable With Use Conditions
Requiring Specific Equipment
We considered use conditions for the adhesive and aerosol solvent
end uses that would reduce the human health risks of using nPB by
reducing exposure levels with requirements for installation and use of
ventilation equipment. We also offer for comment use conditions that
would require aerosol dispensing equipment that would reduce exposure
levels and that would allow use of aerosol blends with reduced amounts
of nPB to maintain acceptable exposure levels.
1. Aerosols
For the aerosol solvent end use, EPA considered proposing a
requirement for installation of ventilation equipment. Such a use
condition would need to specify and define which kinds of ventilation
equipment would be necessary. For example, because one study on
exposure levels found that exposure levels reliably fell in or below
the range that EPA is considering (i.e., 17 to 30 ppm) only where both
local exhaust ventilation and regional ventilation equipment were used,
a possible requirement would be for installation of both local exhaust
ventilation and regional ventilation. We would define local exhaust
ventilation as ventilation that removes vapors from a specific work
location using ducts and fans. We would define regional ventilation as
ventilation that moves air around in a large working area, such as one
or more fans used for an entire room. A problem with requiring the type
of ventilation equipment that all facilities must use is that it still
might not provide enough ventilation in some situations and in other
situations may be unnecessary to meet an exposure limit.
Another approach for aerosols we considered was to require a
specific level of ventilation. Possible criteria for the level of
ventilation would be the air flow rate, in cubic feet per minute (cfm)
or cubic meters per second, or the face velocity at the location where
a user would work, in feet per minute (fpm) or meters per second face
velocity. Based on both modeling and exposure data from one study (ICF,
2006a; Linnel, 2003), an appropriate air flow rate for nPB-based
aerosols would be greater than 1900 cfm and an appropriate face
velocity would be 170 fpm. Alternatively, we considered requiring that
facilities meet the guidelines for face velocity in spray booths from
the ACGIH Ventilation Manual, in the range of 100 to 150 fpm, depending
on the specific type of booth (ACGIH, 2002).
These options would appear to provide greater flexibility for
industry compared to finding nPB unacceptable in aerosol solvents.
However, our understanding is that in most aerosol applications, it
might not be feasible to install adequate ventilation, and thus, to
reduce human health risks. In the case of benchtop cleaning or
degreasing, such as during rework of individual parts that are not yet
sufficiently clean, it is possible to transport the part to a hood or
spray booth to provide sufficient ventilation. However, for
applications that require in-place cleaning such as cleaning energized
electrical contacts and switches, maintenance in underground mines, or
cleaning hot elevator motors, it is not feasible to install ventilation
equipment in place or to remove the parts for cleaning in ventilation
equipment (CSMA, 1998; Linnell, 2003). Information available to EPA
shows that benchtop cleaning is perhaps 25% or less of the market for
the ODS being replaced in aerosols (US EPA, 2004) and that electrical
contact cleaning makes up the vast majority of the market for nPB-based
aerosols (Williams, 2005); thus, we expect that necessary ventilation
cannot be installed in most aerosol applications for nPB. It would be
difficult to explain and potentially confusing for users that an
aerosol product may be used for cleaning in one location in a facility,
but not in another, particularly when the ODS being substituted for
could be used in all locations at safe exposure levels. Further, it
would be difficult for EPA to enforce use conditions on ventilation
equipment, because aerosols are portable and can easily be used outside
of the ventilation equipment. Other acceptable substitutes, such as
blends of HFEs or HFCs and trans-dichloroethylene, are available in
these end uses.
Another option that the Agency considered is finding nPB acceptable
as an aerosol solvent, subject to the use condition that the aerosol
product must be dispensed from a device or a system that is capable of
maintaining acceptable exposure levels. The Agency is aware of at least
two remote dispensing systems that could potentially mitigate exposures
when used with low-pressure aerosols (Micro Care's Trigger
GripTM and Miller Stephenson's Cobra[supreg] Solvent Spray
Cleaning Brush). Vendor data indicates that each aerosol can may last
twice as long when using a remote dispensing system, compared to
standard aerosol usage, indicating the ability to halve average
exposure levels and reduce total solvent use (Micro Care, 2006).
However, these types of systems would only be practical for benchtop
cleaning, and not electrical contact cleaning, which comprises the
majority of nPB aerosol use. The Agency requests comment on the
viability and enforceability of a use condition requiring aerosol
dispensing systems or other mitigation devices that could provide
sufficient performance while
[[Page 30196]]
ensuring acceptable workplace exposure levels of nPB.
Finally, the Agency considered another option by which the use of
nPB would be acceptable in aerosol solvent uses, subject to the
condition that users may only use blends of no more than fifty percent
nPB and the remainder being propellants and other solvents, with
manufacturer's recommended exposure guidelines for compounds other than
nPB being no lower than 100 ppm. Based on exposure modeling performed
on simulations of several commercial blends of nPB and another compound
with a higher exposure limit (HFC-365mfc), it appears that users should
be able to maintain exposures reliably below the range that EPA is
considering for acceptability (i.e., 17 to 30 ppm) when using a blend
containing no more than fifty percent nPB by weight at the ventilation
levels modeled (ICF, 2006a). We note that the modeling does not
consider the possibility that a user might need to use more of a blend
with less nPB, since nPB is more aggressive than many other solvents
used in aerosols. It also does not address exposure levels in confined
spaces as might occur during in-place cleaning with aerosols. We
request comment and relevant, empirical data on the 8-hour TWA
exposures that can be reliably attained when using blends containing
50% or less of nPB by weight. In order to make this option enforceable,
EPA would require users to keep records of nPB-containing aerosol
blends they purchase, including the MSDS or other documentation of the
proportion of nPB in the blend they use. We request comment on whether
this is a feasible, enforceable option and whether it would provide
useful flexibility to industry while ensuring adequate health
protection.
2. Adhesives
EPA also considered use conditions for ventilation equipment or for
specific ventilation levels for use of nPB-based adhesives. However, to
date, we have found no study that demonstrates a ventilation option
that could consistently achieve even the highest level within the range
that EPA is considering for acceptability when using spray adhesives.
Even with state-of-the-art ventilation equipment installed with the
expert assistance of NIOSH, adhesives users were not able to lower
exposure limits sufficient to protect the vast majority of their
workers. Modeling of different levels of adhesive usage and
ventilation, based on conditions at different facilities indicates that
air flow rates would need to be more than 100,000 cfm. Even this high
air flow rate might not be sufficient, since an air flow rate of 28,500
cfm resulted in exposure levels of 3.5 to 35 times an acceptable
exposure level, depending on the amount of adhesive used (ICF, 2006a,
Att. D). Less toxic substitutes such as water-based adhesives and
acetone-based adhesives are available in this end use.
VIII. What are the anticipated costs of this regulation to the
regulated community?
As part of our rulemaking process, EPA estimated potential economic
impacts of this proposed regulation. In our analysis, we assumed that
capital costs are annualized over 15 years or less using a discount
rate for determining net present value of 7.0%. Because the use
condition for coatings still permits nPB's use in the only known
coatings application using nPB, we find no additional cost to the user
community from this regulatory provision. We found that if this
proposed rule were to become final, the cost to the user community of
the unacceptability determinations, which are regulatory prohibitions
on the use of nPB in adhesives and aerosols, would be in the range of
$2.3 to $6.7 million per year for adhesive users and $36.3 to 39.7
million per year for aerosol users.
EPA also estimated the cost to the user community of the use
conditions in the proposed alternate approach for aerosols, adhesives,
and coatings. The requirements for users to meet an acceptable exposure
limit and to perform exposure monitoring would be in the range of $42.3
to 67.5 million per year. The upper end of the range of estimated
impacts assumes laboratory grade ventilation for aerosols, which we
expect to be significantly more expensive than standard industrial fume
hoods or spray booths (approximately $10,000 compared to $1,000 for
each hood). For coatings, use of nPB is limited to a single facility
that already performs workplace exposure monitoring, and thus, no new
costs would be incurred. For aerosols and adhesives, we assumed the
installation of fume hoods or spray booths, the use of personal
protective equipment, and monitoring for 1.9 to 2.0 times per year on
average. Using these assumptions, we calculated the cost of the use
conditions in the proposed alternate approach at $18.0 to 24.0 million
for adhesive users, and $24.3 to 43.5 million for aerosol users. The
estimated cost of the use conditions does not consider that some users
could choose to switch to other alternatives at a lower cost.
Estimated costs of the proposed regulation and proposed alternate
approach are summarized in Table 13. For more detailed information, see
section XIII.C. below and EPA's analysis in the docket (US EPA, 2006).
Table 13.--Estimated Costs of Regulatory Options EPA is Providing for Comment
----------------------------------------------------------------------------------------------------------------
Annual cost of
Sector or end use Requirements under Annual cost of Requirements under alternate
proposed rule proposed rule alternate approach approach
----------------------------------------------------------------------------------------------------------------
Aerosol Solvents.............. Cease use of nPB and $36.3 to 39.7 Achieve 20 ppm; $24.3 to 43.5
switch to a million. exposure monitoring million.
different ODS one or two times per
substitute. year; Recordkeeping.
Coatings...................... Decision applies to None............ Achieve 20 ppm; None.
use nPB in coatings exposure monitoring,
at facilities that, one or two times per
as of May 30, 2007, year; recordkeeping.
have provided EPA
information
demonstrating their
ability to maintain
acceptable workplace
exposures.
Adhesives..................... Cease use of nPB and $2.3 to 6.7 Achieve 20 ppm; $18.0 to 24.0
switch to a million. exposure monitoring, million.
different ODS one or two times per
substitute. year; recordkeeping.
---------------------------------------------------------------------------------
Total..................... ..................... $38.6 to 46.4 ..................... $42.3 to 67.5
million. million.
----------------------------------------------------------------------------------------------------------------
[[Page 30197]]
IX. How do the decisions for EPA's June 2003 proposal compare to those
for this proposal?
Table 14 compares the acceptability determination and evidence
cited in the June 2003 proposal and this proposal.
Table 14.--n-Propyl Bromide Acceptability Decision
------------------------------------------------------------------------
Current proposed
Proposed decision 2003 proposed rule rule--preferred
proposal
------------------------------------------------------------------------
Industrial End Use 1: Aerosol Solvents. to a Use Condition
(Limiting use to
nPB formulations
containing no more
than 0.05% by
weight isopropyl
bromide; AEL of 25
ppm \1\ on 8-hr TWA
recommended.
Industrial End Use 2: Adhesives. to a Use Condition
(Limiting use to
nPB formulations
containing no more
than 0.05% by
weight isopropyl
bromide; AEL of 25
ppm \1\ on 8-hr TWA
recommended.
Industrial End Use 3: Coatings. to Use Conditions
(Decision limited
to coatings at
facilities that, as
of May 30, 2007,
have provided EPA
information
demonstrating their
ability to maintain
acceptable
workplace
exposures.\2\
------------------------------------------------------------------------
\1\ Proposed acceptable exposure limit of 25 ppm adjust upward from
value of 18 ppm based upon nPB's effect on sperm motility from
evaluation of the WIL 2001 Study ``An Inhalation Two-Generation
Reproductive Toxicity Study of 1-Bromopropane in Rats.''
(a) ICF, 2001. ''Brief Discussion of the BMD Approach: Overview of its
Purpose, Methods, Advantages, and Disadvantages.'' Prepared for U.S.
EPA.
(b) ICF, 2002a. ''Risk Screen for Use of N Propyl Bromide.'' Prepared
for U.S. EPA, May, 2002.
(c) ICF, 2002b. Comments on the NTP-Center for the Evaluation of Risks
to Human Reproduction, Final Report on 1-Bromopropane. Cover Letter
Dated 5/9/02.
Also, evaluation of documents by CERHR (2002a, b), Doull and Rozman
(2001), Rodricks (2002), Rozman and Doull (2002), SLR International
(2001), and others.
\2\ For purposes of this proposal, EPA is considering levels within the
range of 17-30 ppm based on the following information on nPB's health
effects for purposes of determining acceptability: estrous cycle
length at 17 to 22 ppm, live litter size at 20 ppm, and sperm motility
at 18 to 30 ppm from evaluation of the WIL 2001 Study ``An Inhalation
Two-Generation Reproductive Toxicity Study of 1-Bromopropane in Rats''
and confirmed by comparison with other studies. Also, considers
evaluation of documents by Stelljes and Wood (2004); TERA (2004); ICF,
2006a; ACGIH (2005); Rozman and Doull (2005); Stelljes (2005); and
others.
X. How can I use nPB as safely as possible?
Below are actions that will help nPB users minimize exposure
levels:
All end uses
All users of nPB should wear appropriate personal
protective equipment, including chemical goggles, flexible laminate
protective gloves (e.g., Viton, Silvershield) and chemical-resistant
clothing. Special care should be taken to avoid contact with the skin
since nPB, like many halogenated solvents, can be absorbed through the
skin. Refer to OSHA's standard for the selection and use of Personal
Protective Equipment, 29 CFR 1910.132.
Limit worker exposure to solvents to minimize any
potential adverse health effects. Workers should avoid staying for long
periods of time in areas near where they have been using the solvent.
Where possible, shorten the period during each day when a worker is
exposed. Where respiratory protection is necessary to limit worker
exposures, respirators must be selected and used in accordance with
OSHA's Respiratory Protection standard, 29 CFR 1910.134.
Use less solvent, or use a different solvent, either alone
or in a mixture with nPB.
Follow all recommended safety precautions specified in the
manufacturer's MSDS.
Workers should receive safety training and education that
includes potential health effects of exposure to nPB, covering
information included on the appropriate MSDSs, as required by OSHA's
Hazard Communication Standard (29 CFR 1910.1200).
Request a confidential consultation from your State
government on all aspects of occupational safety and health. You can
contact the appropriate state agency that participates in OSHA's
consultation program. These contacts are on OSHA's web site at http://www.osha.gov/oshdir/consult.html. For further information on OSHA's
confidential consultancy program, visit OSHA's web page at http://www.osha.gov/html/consultation.html.
Use the employee exposure monitoring programs and product
stewardship programs where offered by manufacturers and formulators of
nPB-based products.
If the manufacturer or formulator of your nPB-based
product does not have an exposure monitoring program, we recommend that
you start your own exposure monitoring program, and/or request a
confidential consultation from your State government. A medical
monitoring program should be established for the early detection and
prevention of acute and chronic effects of exposure to nPB. The
workers' physician(s) should be given information about the adverse
health effects of exposure to nPB and the workers' potential for
exposure.
Spray applications
For spray applications (e.g., aerosols), consider your
available options, and if using nPB, use sufficient ventilation to
reduce exposure to maintain acceptable exposure levels.
For ventilation, we recommend that you follow the design
guidelines for ventilation in ACGIH's Industrial Ventilation: A Manual
of Recommended Practice (ACGIH, 2002). In particular, the guidelines in
Chapter 10.75 are appropriate for spray booths, and the
[[Page 30198]]
guidelines in Chapter 10.35 are appropriate for laboratory hoods.
The ACGIH Ventilation Manual recommends a minimum flow
rate of 150 cubic feet per minute (cfm) for each sq-ft of opening for a
small booth with at least 4 sq-ft of open face area. This equates to an
average face velocity of 150 ft/min. For a large booth, the recommended
face velocity is 100 ft/min for walk-in booths and 100 to 150 ft/min
for a large spray booth where the operator works outside. In general,
the opening should be kept as small as possible to accommodate the
work-pieces, generally 12 inches wider and taller than the largest
piece of work. If all spraying is not directed towards the back of the
booth or the booth is too shallow for the size of the pieces being
sprayed or if disruptive air currents are present at the face of the
booth, a greater flow of air will be needed.
We note that these steps are useful for reducing exposure to any
industrial solvent, and not just nPB.
XI. Statutory and Executive Order Reviews
A. Executive Order 12866: Regulatory Planning and Review
Under Executive Order (EO) 12866 (58 FR 51735, October 4, 1993),
this action is a ``significant regulatory action.'' It raises novel
legal or policy issues arising out of legal mandates, the President's
priorities, or the principles set forth in the Executive Order.
Accordingly, EPA submitted this action to the Office of Management and
Budget (OMB) for review under EO 12866 and any changes made in response
to OMB recommendations have been documented in the docket for this
action.
In addition, EPA prepared an analysis of the potential costs and
benefits associated with this action. This analysis is contained in the
document ``Analysis of Economic Impacts of Proposed nPB Rule on
Aerosols and Adhesives.'' A copy of the analysis is available in the
docket for this action (Ref. EPA-HQ-OAR-2002-0064) and the analysis is
briefly summarized here. EPA estimates the total costs of the proposed
rule to between $38.6 and 46.4 million per year.
B. Paperwork Reduction Act
The information collection requirements in this proposed rule have
been submitted for approval to the Office of Management and Budget
(OMB) under the Paperwork Reduction Act, 44 U.S.C. 3501 et seq. The
Information Collection Request (ICR) document prepared by EPA has been
assigned EPA ICR number 2224.01.
If the provisions of this proposed rule become final (i.e., if the
proposed regulatory language at the end of this document is finalized),
there would be no new information collection burden. This proposed rule
contains no new requirements for reporting or recordkeeping. OMB has
previously approved the information collection requirements contained
in the existing regulations in subpart G of 40 CFR part 82 under the
provisions of the Paperwork Reduction Act, 44 U.S.C. 3501 et seq. and
has assigned OMB control number 2060-0226 (EPA ICR No. 1596.06). This
ICR included five types of respondent reporting and record-keeping
activities pursuant to SNAP regulations: Submission of a SNAP petition,
filing a SNAP/Toxic Substance Control Act (TSCA) Addendum, notification
for test marketing activity, record-keeping for substitutes acceptable
subject to use restrictions, and record-keeping for small volume uses.
However, if EPA were to finalize the proposed alternate approach
described in section VII.A of this preamble, users of nPB would have an
information collection burden from exposure monitoring and
recordkeeping. Under the proposed alternate approach, users of nPB
would be required to monitor worker exposure initially and periodically
(usually every 6 months) and keep records of these exposure data at the
facility for at least three years from the date the samples were taken.
This data is necessary to ensure that users of nPB are meeting the
regulatory use conditions. If the data indicates that the use condition
is not being met, it could be used by EPA or citizens in an enforcement
action against the facility. These data would be considered available
to the public and would not be considered confidential.
The estimated burden of recordkeeping for the entire regulated
community under the proposed alternate approach is as much as $7.0
million and 13,170 hours per year. The estimated recordkeeping burden
for a typical user is $96 and 0.18 hours per worker per monitoring
event. We estimate approximately 1.9 monitoring events per year per
worker, assuming that roughly 90% of exposed workers must be monitored
every six months and 10% must be monitored once annually. We estimate
that up to 35,000 workers would be monitored for exposure to nPB. Costs
under the proposed alternate approach include the annual cost of
purchasing passive organic exposure monitoring badges, the annual cost
of services for analyzing the resulting exposure, and the annual cost
of reviewing and filing the data up to 2 times per year.
Burden means the total time, effort, or financial resources
expended by persons to generate, maintain, retain, or disclose or
provide information to or for a Federal agency. This includes the time
needed to review instructions; develop, acquire, install, and utilize
technology and systems for the purposes of collecting, validating, and
verifying information, processing and maintaining information, and
disclosing and providing information; adjust the existing ways to
comply with any previously applicable instructions and requirements;
train personnel to be able to respond to a collection of information;
search data sources; complete and review the collection of information;
and transmit or otherwise disclose the information.
An Agency may not conduct or sponsor, and a person is not required
to respond to, a collection of information unless it displays a
currently valid OMB control number. The OMB control numbers for EPA's
regulations are listed in 40 CFR part 9 and 48 CFR chapter 15.
To comment on the Agency's need for this information, the accuracy
of the provided burden estimates, and any suggested methods for
minimizing respondent burden, including through the use of automated
collection techniques, EPA has established a public docket for this
rule, which includes this ICR, under Docket ID number EPA-HQ-OAR-2002-
0064. Submit any comments related to the ICR for this proposed rule to
EPA and OMB. See Addresses section at the beginning of this notice for
where to submit comments to EPA. Send comments to OMB at the Office of
Information and Regulatory Affairs, Office of Management and Budget,
725 17th St., NW., Washington, DC 20503, marked ``Attention: Desk
Officer for EPA.'' Include the ICR number in any correspondence. Since
OMB is required to make a decision concerning the ICR between 30 and 60
days after May 30, 2007, a comment to OMB is best assured of having its
full effect if OMB receives it by June 29, 2007. The final rule will
respond to any OMB or public comments on the information collection
requirements contained in this proposal.
C. Regulatory Flexibility Act
The Regulatory Flexibility Act (RFA) generally requires an agency
to prepare a regulatory flexibility analysis of any rule subject to
notice and comment rulemaking requirements under the Administrative
Procedure Act or any
[[Page 30199]]
other statute unless the agency certifies that the rule will not have a
significant economic impact on a substantial number of small entities.
Small entities include small businesses, small organizations, and small
governmental jurisdictions. The RFA provides default definitions for
each type of small entity. Small entities are defined as: (1) A small
business as defined by the Small Business Administration's (SBA)
regulations at 13 CFR 121.201; (2) a small governmental jurisdiction
that is a government of a city, county, town, school district or
special district with a population of less than 50,000; and (3) a small
organization that is any not-for-profit enterprise which is
independently owned and operated and is not dominant in its field.
However, the RFA also authorizes an agency to use alternate definitions
for each category of small entity, ``which are appropriate to the
activities of the agency'' after proposing the alternate definition(s)
in the Federal Register and taking comment. 5 U.S.C. 601(3)-(5). In
addition, to establish an alternate small business definition, agencies
must consult with SBA's Office of Advocacy.
EPA proposed an alternate definition for regulatory flexibility
analyses under the RFA for rules related to the use of nPB as an
alternative to ozone-depleting substances (ODS) in metals, precision,
and electronics cleaning, adhesives, and aerosol solvents in the June
2003 NPRM (68 FR 33309, June 3, 2003). EPA established this final
definition under section 601(3) of the RFA when we promulgated the
final rule on the acceptable use of nPB in metals, precision, and
electronics cleaning in the Rules and Regulations section of today's
Federal Register. For purposes of assessing the economic impacts of
this proposed rule on small entities, EPA defined ``small business'' as
a small business with less than 500 employees, rather than use the
individual SBA size standards for the numerous NAICS subsectors and
codes. We believe that no small governments or small organizations are
affected by this rule. EPA chose to use the alternate definition to
simplify the economic analysis. This approach slightly reduced the
number of small businesses included in our analysis and slightly
increased the percentage of small businesses for whom the analysis
indicated the use of nPB in accordance with this proposed rule may have
an economically significant impact. Furthermore, this size standard was
set by the Small Business Administration for all NAICS codes for
businesses using nPB-based adhesives, one of the end uses that would be
affected by this rule.
After considering the economic impacts of this proposed rule on
small entities, I certify that this action will not have a significant
economic impact on a substantial number of small entities. This rule
proposes to list nPB as an unacceptable substitute for ODS in aerosols
and adhesives. EPA has analyzed the economic impacts of switching from
nPB to other alternative aerosol solvents or adhesives. EPA estimates
that up to 3,380 small industrial end users currently use nPB in the
end uses addressed by this proposed rule and thus could be subject to
the regulatory impacts of this rule. This number includes approximately
3,100 users of nPB-based aerosol solvents, and 280 users of nPB-based
adhesives. Considering the regulatory impacts on adhesive and aerosol
users that must switch to other alternatives, we found that up to 258
(8%) of small businesses would experience impacts of 1% or greater of
annual sales and no small businesses would experience impacts of 3% or
greater of annual sales. Based on the relatively small number and low
percentage of small businesses that would experience significant
economic impacts, EPA concludes that this rule would not have a
significant economic impact on a substantial number of small entities.
In the case of coatings uses, our understanding is that only a
single facility, the Lake City Army Ammunition Plant, is currently
using coatings with nPB as the carrier solvent, and this facility could
continue to use nPB following its current practices. Therefore, we
consider there to be no economic impact of this rule on coatings users
and have not done further analysis for this end use.
Types of businesses that would be subject to this proposed rule
include:
Manufacturers of computers and electronic equipment that
clean with nPB cleaning solvents (NAICS subsector 334).
Manufacturers of appliances, electrical equipment, and
components that require oil, grease, and solder flux to be cleaned off
(NAICS subsection 335).
Manufacturers of transportation equipment, such as
aerospace equipment that requires cleaning either in a tank or with
aerosols, or aircraft seating, which is assembled using adhesives
containing nPB as a carrier solvent; and ship or boat builders applying
adhesives with nPB (NAICS subsector 336).
Manufacturers of furniture, including various kinds of
furniture with cushions and countertops assembled using adhesives
containing nPB as a carrier solvent (NAICS subsector 337).
Foam fabricators, who assemble foam cushions or sponges
using adhesives containing nPB as a carrier solvent (NAICS code
326150).
In order to consider the resources that affected small businesses
have available to operate and to respond to the proposed regulatory
requirements, EPA compared the cost of meeting the proposed regulatory
requirements to small businesses' annual sales. In our analysis for
this proposed rule, we used the average value of shipments for the
products manufactured by the end user as a proxy for sales or revenues,
since these data are readily available from the U.S. Department of
Commerce. The following tables display the average value of shipments
for different sizes of business and different NAICS subsectors or codes
in the affected industrial sectors. EPA then used data from these
sources to determine the potential economic impacts of this proposed
rule on small businesses.
Table 15.--Average Value of Shipments in NAICS Subsectors Using Aerosol Solvents, by Number of Employees at
Business
----------------------------------------------------------------------------------------------------------------
Average value of shipments per business ($) by NAICS
subsector code
-----------------------------------------------------
Number of employees at business 335, electrical
334, computer equipment, 336,
and electronic appliance, and transportation
products component mfg equipment
----------------------------------------------------------------------------------------------------------------
1 to 4 employees.......................................... 345,007 315,772 412,460
5 to 9 employees.......................................... 1,317,238 1,243,065 1,414,384
10 to 19 employees........................................ 2,566,913 2,483,327 2,573,352
[[Page 30200]]
20 to 49 employees........................................ 5,672,245 5,389,945 5,738,739
50 to 99 employees........................................ 12,951,836 12,650,236 12,735,583
100 to 249 employees...................................... 31,258,875 31,290,638 34,256,544
250 to 499 employees...................................... 84,270,454 77,279,974 86,911,454
Avg. value ship small businesses in sub-sector............ 8,261,788 9,539,205 11,029,561
Avg. value ship all businesses in subsector............... 20,810,094 13,417,905 45,029,773
Avg. value shipments subset small businesses using nPB.... 11,246,045 12,066,562 13,422,547
----------------------------------------------------------------------------------------------------------------
Table 16.--Average Value of Shipments in NAICS Categories Using nPB as a Carrier Solvent in Adhesives, by Number of Employees at Business
--------------------------------------------------------------------------------------------------------------------------------------------------------
Average value of shipments per small business ($) by NAICS sub sector
-----------------------------------------------------------------------------------------
326150,
Number of employees at business 337121, 337110, wood urethane and 336360, motor 337124, metal
upholstered kitchen cabinet other foam vehicle seating household
household and counter tops products (except and interior furniture
furniture polystyrene) trim
--------------------------------------------------------------------------------------------------------------------------------------------------------
1 to 4 employees.............................................. 234,345 156,833 496,318 425,863 187,950
5 to 9 employees.............................................. 963,021 622,744 1,305,183 1,728,132 903,393
10 to 19 employees............................................ 1,771,416 1,141,119 3,152,283 3,082,486 1,431,480
20 to 49 employees............................................ 3,653,623 2,619,197 6,615,331 5,508,370 3,538,684
50 to 99 employees............................................ 8,089,968 7,386,365 13,281,000 14,088,500 7,547,536
100 to 249 employees.......................................... 17,502,175 17,151,091 31,524,872 44,310,286 19,821,719
250 to 499 employees.......................................... 40,250,813 55,982,674 64,119,800 123,803,610 d(1)
Avg. Small Businesses in Sub sector........................... 3,588,297 1,150,768 10,472,992 12,542,725 3,141,720
Avg. ALL Businesses in Sub sector............................. 5,490,101 1,475,602 11,110,822 44,808,573 5,239,747
Avg. Subset Small Businesses using nPB........................ 11,519,540 5,999,622 18,950,068 12,019,847 20,401,301
--------------------------------------------------------------------------------------------------------------------------------------------------------
\(1)\ ``d'' designates ``Data withheld to avoid disclosing data of individual companies; data are included in higher level totals.'' The average value
of shipments for businesses estimates those values marked with ``d,'' and thus may be overestimated or underestimated.
This proposed rule would list nPB as unacceptable for use in
adhesives and aerosols. The available alternatives identified include
adhesive formulations based on water, methylene chloride, or flammable
solvents such as acetone and aerosol formulations of flammable
solvents, combustible solvents, blends of trans-dichloroethylene and
HFEs or HFCs, and HCFC-225ca/cb. We considered various aspects of the
cost of switching to other alternatives, including the cost of meeting
OSHA requirements and the cost of the alternative adhesive. We
specifically request public comment on the assumptions and costs used
in EPA's analysis (US EPA, 2007).
We estimate that up to 9 small businesses using nPB-based
adhesives, or roughly 3% of the 280 or so small businesses that use
nPB-based adhesives, would experience a cost increase (i.e., an impact)
of greater than 1.0% of annual sales, and no small businesses would
experience an impact of greater than 3% of annual sales if this
proposed rule became final. For small businesses using nPB-based
aerosols, we estimate that approximately 249 would experience a cost
increase of greater than 1.0% of annual sales. This equates to roughly
8% of the 3100 or so small businesses currently using nPB-based aerosol
solvents. No small businesses using aerosols would experience an impact
of greater than 3% of annual sales. Approximately eight percent of all
3380 or so small businesses choosing to use nPB in these end uses would
experience an impact of greater than 1.0% of annual sales and no small
businesses would experience an impact of greater than 3.0% of annual
sales. Because of the small total number and small percentage of
affected businesses that would experience an impact of greater than
either 1.0% or 3.0% of annual sales, EPA does not consider this
proposed rule to have a significant economic impact on a substantial
number of small businesses.
We also analyzed the potential small business impacts of the
proposed alternate approach. Under the proposed alternate approach,
users would have to: (1) Meet an exposure level of 20 ppm on an eight-
hour time-weighted average, (2) monitor workers' exposure to nPB using
a personal breathing zone sampler on an eight-hour time-weighted
average initially and periodically (every 6 months or longer, depending
on the concentration during initial monitoring), and (3) keep records
of the worker exposure data on site at the facility for at least three
years from the date of the measurement. We assume that the cost of
following the proposed alternate approach is the cost of installing
ventilation for aerosols and adhesives or emission controls for solvent
cleaning, the cost of using personal protective equipment, and the cost
of monitoring worker exposure. Approximately 67 to 387 aerosol solvent
users (2 to 13 percent), 25 to 54 adhesive users (9 to 19 percent), and
2.6 to 12.6 percent of all 3380 or so small businesses would experience
impacts of greater than 1% of annual sales if they chose to use nPB
subject to the proposed use conditions rather than switching to another
ODS substitute.
[[Page 30201]]
Four to nine users of nPB-based adhesives, or less than 1% of all small
businesses affected by this proposal, would experience impacts of 3% or
greater of annual sales under the proposed alternate approach. Based on
this analysis, the proposed alternate approach would not create a
significant adverse economic impact on a substantial number of small
entities.
Although this proposed rule would not have a significant economic
impact on a substantial number of small entities if it became final,
EPA nonetheless has tried to reduce the impact of this rule on small
entities. Before selecting preferred the regulatory option in this
proposed rule, we considered a number of regulatory options, such as:
Placing a narrowed use limit on the use of nPB in
adhesives and aerosols that would allow its use only in those cases
where alternatives are technically infeasible due to performance or
safety issues. This would have required testing, recordkeeping, and
some installation of capital equipment.
Requiring that when nPB is used in adhesives or aerosols,
it must be used with local ventilation equipment and personal
protective equipment. This would have required further installation of
capital equipment, without necessarily protecting workers as thoroughly
as a required acceptable exposure limit or requiring a switch to
another alternative.
Prohibiting the use of nPB in all end uses.
Retaining the previously proposed requirement for a limit
on iPB content in nPB formulations.
The costs of a number of these options are included in EPA's analysis
(US EPA, 2006; U.S. EPA, 2007).
In developing our regulatory options, we considered information we
learned from contacting small businesses using or selling nPB. EPA
staff visited the site of a small business using nPB for cleaning
electronics. We contacted several fabricators of foam cushions that
have used adhesives containing nPB. We participated in meetings with a
number of adhesive manufacturers and users of adhesives in furniture
construction. We developed a fact sheet and updated our program Web
site to inform small businesses about the proposed rule and to request
their comments.
We continue to be interested in the potential impacts of the
proposed rule on small entities and welcome comments on issues related
to such impacts.
D. Unfunded Mandates Reform Act
Title II of the Unfunded Mandates Reform Act of 1995 (UMRA), Public
Law 104-4, establishes requirements for Federal agencies to assess the
effects of their regulatory actions on State, local, and tribal
governments and the private sector. Under section 202 of the UMRA, EPA
generally must prepare a written statement, including a cost-benefit
analysis, for proposed and final rules with ``Federal mandates'' that
may result in expenditures to State, local, and tribal governments, in
the aggregate, or to the private sector, of $100 million or more in any
one year. Before promulgating an EPA rule for which a written statement
is needed, section 205 of the UMRA generally requires EPA to identify
and consider a reasonable number of regulatory alternatives and adopt
the least costly, most cost-effective or least burdensome alternative
that achieves the objectives of the rule. The provisions of section 205
do not apply when they are inconsistent with applicable law. Moreover,
section 205 allows EPA to adopt an alternative other than the least
costly, most cost-effective or least burdensome alternative if the
Administrator publishes with the final rule an explanation why that
alternative was not adopted. Before EPA establishes any regulatory
requirements that may significantly or uniquely affect small
governments, including tribal governments, it must have developed under
section 203 of the UMRA a small government agency plan. The plan must
provide for notifying potentially affected small governments, enabling
officials of affected small governments to have meaningful and timely
input in the development of EPA regulatory proposals with significant
Federal intergovernmental mandates, and informing, educating, and
advising small governments on compliance with the regulatory
requirements. EPA has determined that this rule does not contain a
Federal mandate that may result in expenditures of $100 million or more
for State, local, and tribal governments, in the aggregate, or the
private sector in any one year. This proposed rule does not affect
State, local, or tribal governments. The enforceable requirements of
the rule for the private sector affect a number of end users in
manufacturing. The estimated cost of the proposed requirements for the
private sector is approximately $38.6 to 46.4 million per year, and the
proposed alternate approach would cost the private sector approximately
$ 42.3 to 67.5 million per year. Therefore, the impact of this rule on
the private sector is less than $100 million per year. Thus, this rule
is not subject to the requirements of sections 202 and 205 of the UMRA.
EPA has determined that this rule contains no regulatory requirements
that might significantly or uniquely affect small governments. This
regulation applies directly to facilities that use these substances and
not to governmental entities.
E. Executive Order 13132: Federalism
Executive Order 13132, entitled ``Federalism'' (64 FR 43255, August
10, 1999), requires EPA to develop an accountable process to ensure
``meaningful and timely input by State and local officials in the
development of regulatory policies that have federalism implications.''
``Policies that have federalism implications'' is defined in the
Executive Order to include regulations that have ``substantial direct
effects on the States, on the relationship between the National
government and the States, or on the distribution of power and
responsibilities among the various levels of government.''
This proposed rule does not have federalism implications. It will
not have substantial direct effects on the States, on the relationship
between the national government and the States, or on the distribution
of power and responsibilities among the various levels of government,
as specified in Executive Order 13132. This regulation applies directly
to facilities that use these substances and not to governmental
entities. Thus, Executive Order 13132 does not apply to this rule.
F. Executive Order 13175: Consultation and Coordination With Indian
Tribal Governments
Executive Order 13175, entitled ``Consultation and Coordination
with Indian Tribal Governments'' (65 FR 67249, November 6, 2000),
requires EPA to develop an accountable process to ensure ``meaningful
and timely input by tribal officials in the development of regulatory
policies that have tribal implications.'' ``Policies that have tribal
implications'' is defined in the Executive Order to include regulations
that have ``substantial direct effects on one or more Indian tribes, on
the relationship between the Federal government and the Indian tribes,
or on the distribution of power and responsibilities between the
Federal government and Indian tribes.''
This proposed rule does not have tribal implications. It will not
have substantial direct effects on tribal governments, on the
relationship between the Federal government and Indian tribes, or on
the distribution of power and responsibilities between the
[[Page 30202]]
Federal government and Indian tribes, as specified in Executive Order
13175.
This proposed rule would not significantly or uniquely affect the
communities of Indian tribal governments, because this regulation
applies directly to facilities that use these substances and not to
governmental entities. Thus, Executive Order 13175 does not apply to
this proposed rule.
G. Executive Order 13045: Protection of Children From Environmental
Health and Safety Risks
Executive Order 13045: ``Protection of Children from Environmental
Health Risks and Safety Risks'' (62 FR 19885, April 23, 1997) applies
to any rule that: (1) Is determined to be ``economically significant''
as defined under Executive Order 12866, and (2) concerns an
environmental health or safety risk that EPA has reason to believe may
have a disproportionate effect on children. If the regulatory action
meets both criteria, the Agency must evaluate the environmental health
or safety effects of the planned rule on children, and explain why the
planned regulation is preferable to other potentially effective and
reasonably feasible alternatives considered by the Agency.
This proposed rule is not subject to the Executive Order because it
is not economically significant as defined in Executive Order 12866,
and because the Agency does not have reason to believe the
environmental health or safety risks addressed by this action present a
disproportionate risk to children. The exposure limits and
acceptability listings in this proposed rule apply to the workplace.
These are areas where we expect adults are more likely to be present
than children, and thus, the agents do not put children at risk
disproportionately.
The public is invited to submit or identify peer-reviewed studies
and data, of which the agency may not be aware, that assessed results
of early life exposure to nPB.
H. Executive Order 13211: Actions That Significantly Affect Energy
Supply, Distribution, or Use
This rule is not a ``significant energy action'' as defined in
Executive Order 13211, ``Actions Concerning Regulations That
Significantly Affect Energy Supply, Distribution, or Use'' (66 FR 28355
(May 22, 2001)) because it is not likely to have a significant adverse
effect on the supply, distribution, or use of energy. This action would
impact manufacturing of various metal, electronic, medical, and optical
products cleaned with solvents containing nPB and products made with
adhesives containing nPB. Further, we have concluded that this rule is
not likely to have any adverse energy effects.
I. National Technology Transfer and Advancement Act
As noted in the proposed rule, Section 12(d) of the National
Technology Transfer and Advancement Act of 1995 (``NTTAA''), Public Law
104-113, section 12(d) (15 U.S.C. 272 note) directs EPA to use
voluntary consensus standards in its regulatory activities unless to do
so would be inconsistent with applicable law or otherwise impractical.
Voluntary consensus standards are technical standards (e.g., materials
specifications, test methods, sampling procedures, and business
practices) that are developed or adopted by voluntary consensus
standards bodies. The NTTAA directs EPA to provide Congress, through
OMB, explanations when the Agency decides not to use available and
applicable voluntary consensus standards.
This action does not involved technical standards. Therefore, EPA
did not consider the use of any voluntary consensus standards. We note
that the American Conference of Governmental Industrial Hygienists
(ACGIH), although it sets voluntary standards, is not a voluntary
consensus standards body. Therefore, use of an acceptable exposure
limit from the ACGIH is not subject to the NTTAA.
XII. References
The documents below are referenced in the preamble. All documents
are located in the Air Docket at the address listed in section I.B.1 at
the beginning of this document. Unless specified otherwise, all
documents are available electronically through the Federal Docket
Management System, Docket EPA-HQ-OAR-2002-0064. Some specific
items are available only in hard copy in dockets A-2001-07 or A-92-42
(legacy docket numbers for SNAP nPB rule and for SNAP program and
submissions). Numbers listed after the reference indicate the docket
and item numbers.
Availability
Harper, 2005. Telephone call from M. Sheppard, EPA to Dr. S. Harper,
ATK. Re: Availability of other methyl chloroform substitutes for the
Lake City Army Ammunition Plant. October 11, 2005. (EPA-HQ-OAR-2002-
0064-0150)
IRTA, 2000. Alternative Adhesive Technologies in the Foam Furniture
and Bedding Industries: A Cleaner Technologies Substitution
Assessment, Cost and Performance Evaluation. Michael Morris and Katy
Wolf, Institute for Research and Technical Assistance. Prepared for
the U.S. EPA Office of Pollution Prevention Technology, June 2000.
(A-2001-07, II-D-70)
Seilheimer, 2001. Telephone Log of April 4, 2001 call between
Margaret Sheppard, EPA, and Bob Seilheimer, Imperial Adhesives. (A-
2001-07, II-B-5)
Williams, 2005. Notes on conversation of Ed Williams, Technical
Manager, LPS Laboratories, and Margaret Sheppard, EPA. November 3,
2005 (EPA-HQ-OAR-2002-0064-0198)
Impacts on the Atmosphere, Local Air Quality, and Other Environmental
Impacts
Atmospheric and Environmental Research, Inc., 1995. Estimates of the
Atmospheric Lifetime, Global Warming Potential and Ozone Depletion
Potential of n-Propyl Bromide. Independent study prepared for
Albemarle Corporation. (A-2001-07, II-D-17)
ATSDR, 1994. Toxicological Profile For Acetone. Agency for Toxic
Substances and Disease Registry. May, 1994. Available at http://www.atsdr.cdc.gov/toxprofiles/tp21-c5.pdf (EPA-HQ-OAR-2002-0064-
0118)
ATSDR, 1996. Toxicological Profile For 1,2-Dichloroethene. Agency
for Toxic Substances and Disease Registry. August, 1996. Available
at http://www.atsdr.cdc.gov/toxprofiles/tp87-c5.pdf (EPA-HQ-OAR-
2002-0064-0113)
ATSDR, 1997. Toxicological Profile For Trichloroethylene. Agency for
Toxic Substances and Disease Registry. September, 1997. Available
athttp://www.atsdr.cdc.gov/toxprofiles/tp19-c5.pdf (EPA-HQ-OAR-2002-
0064-0123)
ATSDR, 2004. Draft Toxicological Profile For 1,1,1-Trichloroethane.
Agency for Toxic Substances and Disease Registry. September, 2004.
Updated draft for comment. Available at http://www.atsdr.cdc.gov/toxprofiles/tp70-c6.pdf (EPA-HQ-OAR-2002-0064-0132)
EDSTAC, 1998. Final Report of the Endocrine Disruptor Screening and
Testing Advisory Committee. August, 1998. (EPA-HQ-OAR-2002-0064-
0136)
Fisher Scientific, 2001. Material Safety Data Sheet for acetone.
Updated March 19, 2001. Available at http://www.mhatt.aps.anl.gov/dohn/msds/acetone.html (EPA-HQ-OAR-2002-0064-0129)
Geiger et al., 1998. Geiger, D.L., Call, D.J., and Brooke, L.T.
1988. Acute Toxicities of Organic Chemicals to Fathead Minnows
(Pimephales promelas), Vol. 4. In: Center for Lake Superior
Environmental Stud., Univ. of Wisconsin-Superior, Superior, WI
I:355. (Summarized in ICF, 2004a)
HSDB, 2004. Hazardous Substances Databank File for 1-Bromopropane.
Accessed 1/2004 from the World Wide Web at http://
toxnet.nlm.nih.gov/cgi-bin/sis/
[[Page 30203]]
search/f?./temp/dLwM9e:1 (Summarized in ICF, 2004a)
ICF, 2003a. ICF Consulting. Revised Evaluation of the Global Warming
Potential for n-Propyl Bromide. (EPA-HQ-OAR-2002-0064-0164)
ICF, 2004a. ICF Consulting. Memo to E. Birgfeld, EPA, re: nPB
Aquatic Toxicity. January 19, 2004. (EPA-HQ-OAR-2002-0064-0177)
ICF, 2006a. ICF Consulting. Risk Screen on Substitutes for Ozone-
Depleting Substances for Adhesive, Aerosol Solvent, and Solvent
Cleaning Applications. Proposed Substitute: n-Propyl Bromide. April
18, 2006. Attachments: A, Determination of an AEL; B, Derivation of
an RfC; C, Evaluation of the Global Warming Potential; D,
Occupational Exposure Analysis for Adhesive Applications; E,
Occupational Exposure Analysis for Aerosol Solvent Applications; F,
General Population Exposure Assessment for n-Propyl Bromide
LaGrega, M., Buckingham, P., Evans, J., and Environmental Resources
Management, 2001. Hazardous Waste Management. Second Edition.
McGraw-Hill, New York, NY. 2001. (EPA-HQ-OAR-2002-0064-0112)
Linnell, 2003. Comments from the Electronics Industry Alliance.
(EPA-HQ-OAR-2002-0064 items -0043, -0044, and -0045)
MOP 18, 2006. Report of the Eighteenth Meeting of the Parties to the
Montreal Protocol on Substances that Deplete the Ozone Layer.
November 16, 2006. (EPA-HQ-OAR-2002-0064-0163)
NPS, 1997. Irwin, R.J., M. VanMouwerik, L. Stevens, M.S. Seese, and
W. Basham. 1997. Environmental Contaminants Encyclopedia. National
Park Service, Water Resources Division, Fort Collins, Colorado.
(EPA-HQ-OAR-2002-0064-0086)
Steminiski, 2003. July 27, 2003 Comment from J. Steminiski, Ph.D.
(EPA-HQ-OAR-2002-0064-0035 and -0043)
U.S. Economic Census, 2002a. General Summary: 2002. Subject Series.
Report No. EC02-31SG-1, October, 2005. U.S. Census Bureau. (EPA-HQ-
OAR-2002-0064-0133)
U.S. Economic Census, 2002b. U.S. Economic Census for Island Areas,
2002. Report for Northern Marianas Islands, Rpt. No. IA02-00A-NMI,
May, 2004. U.S. Census Bureau. (EPA-HQ-OAR-2002-0064-0091)
U.S. Economic Census, 2002c. U.S. Economic Census for Island Areas,
2002. Report for Guam, Rpt. No. IA02-00A-GUAM, March, 2005. U.S.
Census Bureau. (EPA-HQ-OAR-2002-0064-0102)
U.S. Economic Census, 2002d. U.S. Economic Census for Island Areas,
2002. Report for Virgin Islands, Rpt. No. IA02-00A-VI , April, 2005.
U.S. Census Bureau. (EPA-HQ-OAR-2002-0064-0131)
U.S. Economic Census, 2002e. U.S. Economic Census for Island Areas,
2002. Report for American Samoa, Rpt. No. IA02-00A-AS, April, 2005.
U.S. Census Bureau. (EPA-HQ-OAR-2002-0064-0103)
U.S. Economic Census, 2002f. U.S. Economic Census for Island Areas,
2002. Report for Puerto Rico: Manufacturing, Rpt. No. IA02-00I-PRM,
October, 2005. U.S. Census Bureau. (EPA-HQ-OAR-2002-0064-0107)
U.S. EPA, 1980. Ambient Water Quality Criteria for
Dichloroethylenes. EPA 440/5-80-041 October, 1980. Available at
http://www.epa.gov/waterscience/pc/ambientwqc/dichloroethylenes80.pdf
U.S. EPA, 1992. Hazard Assessment Guidelines for Listing Chemicals
on the Toxic Release Inventory, Revised Draft. Washington, DC:
Office of Pollution, Prevention and Toxics. As referenced in ICF,
2004f.
U.S. EPA, 1994a. Chemical Summary for Methyl Chloroform, prepared by
Office of Pollution Prevention and Toxics, August, 1994. (EPA-HQ-
OAR-2002-0064-0121)
WMO, 2002: Scientific Assessment of Ozone Depletion: 2002, Global
Ozone Research and Monitoring Project--Report No. 47, Geneva, 2003
Full report available online at http://esrl.noaa.gov/csd/assessments/ (A-2001-07, II-A-20)
Wuebbles, Donald J. 2002. ``The Effect of Short Atmospheric
Lifetimes on Stratospheric Ozone.'' Written for Enviro Tech
International, Inc. Department of Atmospheric Sciences, University
of Illinois-Urbana. (EPA-HQ-OAR-2002-0064-0114)
Flammability and Fire Safety
BSOC, 2000. February 1, 2000 Tabulation of Flammability Studies on
n-Propyl Bromide from the Brominated Solvents Committee, and other
information on flammability of n-propyl bromide. (A-2001-07, II-D-
45)
Miller, 2003. Albemarle Corporation comments-Flash Point Data for n-
Propyl Bromide. (EPA-HQ-OAR-2002-0064-0040)
Morford, 2003a. Enviro Tech International Comment re Section IV D
Flammability with Exhibits (7/25/03) (EPA-HQ-OAR-2002-0064-0030)
Morford, 2003b. Enviro Tech International Supporting Exhibits on
Flammability (7/25/03) (EPA-HQ-OAR-2002-0064-0031)
Morford, 2003c. Enviro Tech Int. Flammability of nPB & Comparison
With Methylene Chloride-Additional Comments on Flammability (7/29/
03) (EPA-HQ-OAR-2002-0064-0036)
Shubkin, 2003. R. Shubkin, Poly Systems, EPA received 7/23/03 Re:
Comment on Flammability of n-Propyl Bromide as Discussed in Proposed
Rule Published in Federal Register (EPA-HQ-OAR-2002-0064-0025)
Weiss Cohen, 2003. T. Weiss Cohen, Dead Sea Bromine Group, 7/31/2003
Comment to Federal Register Proposed Rules of June 3, 2003, on
Protection of Stratospheric Ozone: Listing of Substitutes for Ozone-
Depleting Substances--n-Propyl Bromide (EPA-HQ-OAR-2002-0064-0053)
Impact on human health; how did EPA assess impacts on human health?
ACGIH, 1991. Skin Notation Documentation for Methyl Chloride.
Available online at http://www.acgih.org.
ACGIH, 2005. Documentation for Threshold Limit Value for 1-
Bromopropane. 2005. Available online at www.acgih.org.
Albemarle, 2003. Product Description for Abzol[supreg] Cleaners.
2003. (EPA-HQ-OAR-2002-0064-0148)
Beck and Caravati, 2003. Neurotoxicity associated with 1-
bromopropane exposure. Utah Poison Control Center, University of
Utah, Salt Lake City, UT. J Toxicology Clinical Toxicology
41(5):729. (Abstract from conference). 2003. (EPA-HQ-OAR-2002-0064-
0111)
CERHR, 2002a. NTP-Center for the Evaluation of Risks to Human
Reproduction Expert Panel Report on the Reproductive and
Developmental Toxicity of 1-Bromopropane [nPB]. March 2002. (EPA-HQ-
OAR-2002-0064-0096)
CERHR, 2002b. NTP-Center for the Evaluation of Risks to Human
Reproduction Expert Panel Report on the Reproductive and
Developmental Toxicity of 2-Bromopropane [iPB]. March 2002. (EPA-HQ-
OAR-2002-0064-0083)
CERHR, 2003a. NTP-CERHR Monograph on the Potential Human
Reproductive and Developmental Effects of 1-Bromopropane. October
2003. (EPA-HQ-OAR-2002-0064-0084)
CERHR, 2003b. NTP-CERHR Monograph on the Potential Human
Reproductive and Developmental Effects of 2-Bromopropane. October
2003. (EPA-HQ-OAR-2002-0064-0079)
CERHR, 2004a. NTP-CERHR Expert Panel report on the reproductive and
developmental toxicity of 1-bromopropane. Center for the Evaluation
of Risks to Human Reproduction. Repro Toxicol. Vol. 18, pp. 157-188.
2004. (EPA-HQ-OAR-2002-0064-0096)
CERHR, 2004b. NTP-CERHR Expert Panel report on the reproductive and
developmental toxicity of 2-bromopropane. Boekelheide, et al. Repro
Toxicol. Vol. 18, pp. 189-217. 2004. (EPA-HQ-OAR-2002-0064-0098)
Chemtura, 2006. Material Safety Data Sheet for n-propyl bromide.
April, 2006. (EPA-HQ-OAR-2002-0064-0151)
ClinTrials, 1997a. A 28-Day Inhalation Study of a Vapor Formulation
of ALBTA1 in the Albino Rat. Report No. 91189. Prepared by
ClinTrials BioResearch Laboratories, Ltd., Senneville, Quebec,
Canada. May 15, 1997. Sponsored by Albemarle Corporation, Baton
Rouge, LA. (A-91-42, X-A-4)
ClinTrials, 1997b. ALBTA1: A 13-Week Inhalation Study of a Vapor
Formulation of ALBTA1 in the Albino Rat. Report No. 91190. Prepared
by ClinTrials BioResearch Laboratories, Ltd., Senneville, Quebec,
Canada. February 28, 1997. Sponsored by Albemarle Corporation, Baton
Rouge, LA. (A-91-42, X-A-5)
[[Page 30204]]
Confidential submission, 1998. Airborne Exposure Assessment of 1-
Bromopropane, 1998. (A-2001-07, II-D-89).
Dunson et al, 2002. Dunson, D., Colombo, and B., Baird, D. Changes
with age in the level and duration of fertility in the menstrual
cycle. Human Reproduction, Vol. 17, No. 5, pp. 1399-1403, 2002.
(EPA-HQ-OAR-2002-0064-0120)
Elf Atochem, 1995. Micronucleus Test by Intraperitoneal Route in
Mice. n-Propyl Bromide. Study No. 12122 MAS. Study Director,
Brigitte Molinier. Study performed by Centre International de
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Enviro Tech International, 2006. Material Safety Data Sheet for
Ensolv (n-propyl bromide solvent) (EPA-HQ-OAR-0064-0143)
Farr, 2003. Comment on proposed rule on n-propyl bromide from Craig
Farr, Atofina. July 31, 2003. (EPA-HQ-OAR-2002-0064-0060)
Fueta et al., 2002. Y. Fueta, K. Fukunaga, T. Ishidao, H. Hori.
Hyperexcitability and changes in activities of Ca2+/calmodulin-
dependent kinase II and mitogen-activated protein kinase in the
hippocampus of rats exposed to 1-bromopropane. 2002. Life Sciences
72 (2002) 521-529. (EPA-HQ-OAR-2002-0064-0115)
Fueta et al., 2004. Y. Fueta, T. Fukuda, T. Ishidao, H. Hori.
Electrophysiology and immunohistochemistry in the hippocampal CA1
and the Dentate Gyrus of Rats Chronically exposed to 1-Bromopropane,
a Substitute for Specific Chlorofluorocarbons. Neuroscience 124
(2004) 593-603. (EPA-HQ-OAR-2002-0064-0142)
Furuhashi, et al., 2006. K. Furuhashi, J. Kitoh, J. Tsukamura, K.
Maeda, H. Wang, W. Li, S. Ichihara, T. Nakajima, and G. Ichihara.
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Great Lakes Chemical Corporation, 2001. Letter from E. Stouder,
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HESIS, 2003. California Department of Health Services--HESIS 1-
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Honma et al., 2003. Honma, T., Suda, M., Miyagawa, M. ``Inhalation
of 1-bromopropane causes excitation in the central nervous system of
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Huntingdon Life Sciences, 2001. A Developmental Toxicity Study in
Rat Via Whole Body Inhalation Exposure. (A-2001-07, II-D-27) ICF,
2002a. Risk Screen for Use of N-Propyl Bromide. ICF Consulting.
Prepared for U.S. EPA, May, 2002. (EPA-HQ-OAR-2002-0064-0006 through
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ICF, 2003. ICF Consulting. General Population Exposure Assessment
for N-Propyl Bromide. June 03, 2003. (EPA-HQ-OAR-2002-0064-0011)
ICF, 2004b. ICF Consulting. External Expert Review Panel on N-Propyl
Bromide. December 13, 2004.
ICF, 2004c. ICF Consulting. ICF Consulting Review of the TERA
Report. December 13, 2004.
ICF, 2004d. ICF Consulting. Review of ACGIH's Proposed Threshold
Limit Value for 1-Bromopropane. April 26, 2004.
ICF, 2006a. Full citation given above in section on ``Impacts on the
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ICF, 2006b. ICF Consulting. Revised Memorandum regarding RTI
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ICF, 2006c. ICF Consulting. Evaluation of Memorandum from Dr. M.
Stelljes. April, 2006.
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Xuncheng Ding, Hailan Wang, Yideng Liang, Simeng Peng, Seiichiro
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Xiaoyun Wu, William M. Valentine, and Yasuhiro Takeuchi.
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Env'l Health Perspectives, 30 June 2004. (EPA-HQ-OAR-2002-0064-0139)
Ishidao et al., 2002. Ishidao, T., Kunugita, N., Fueta, Y.,
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(EPA-HQ-OAR-2002-0064-0029)
Lake City Army Ammunition Plant, 2004. March 9, 2004 Industrial
Hygiene Air Sampling Report for Normal Propyl Bromide Based Mouth
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Majersik et al., 2004. Chronic Exposure to 1-Bromopropane Associated
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Miller, 2005. ``1-Bromopropane: A Private Neurological Practice
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Morford, 2003d. White Paper: ``EPA Is Unlawfully Regulating
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Morford, 2003e. Comment regarding proposed restriction on isopropyl
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(EPA-HQ-OAR-2002-0064-0042)
Morford, 2003f. Support for EPA Proposal to Approve n propyl bromide
and Comments Pursuant to Section D. Flammability of Protection of
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Substances--n-Propyl Bromide: Proposed Rule Federal Register Vol. 68
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Morford, 2003g. Enviro Tech International, Inc. Combined Exhibits to
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Morford, 2003h. Initial Comments to Protection of Stratospheric
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[[Page 30205]]
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Rodricks, 2002. October 21, 2002 remarks from Dr. J. Rodricks,
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derivation of an OEL for n-propyl bromide with cover letter to EPA
from Enviro Tech International (A-2001-07, II-D-65)
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and mice. Research Triangle Institute report for the National
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0081, -0082, -0101, -0104, -0137, -0137.1)
Ruckriegel, 2003. Comment on n-Propyl Bromide Recommended Workplace
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0055)
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Stelljes, 2003. Comments from Dr. Marc Stelljes, SLR International,
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Stelljes and Wood, 2004. Stelljes, M., Wood, R. Development of an
occupational exposure limit for n-propylbromide using benchmark dose
methods. Regulatory Toxicology and Pharmacology 40 (2004) 136-150
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[[Page 30206]]
WIL, 2001. WIL Research Laboratories. ``An inhalation two-generation
reproductive toxicity study of 1-bromopropane in rats.'' Sponsored
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Dysfunction in Rats. Toxicol Sci 71:96-103 (EPA-HQ-OAR-2002-0064-
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Listings for Each End Use
Beck and Caravati, 2003. Full citation above for ``Human Health''
section.
Calhoun County, 2005. Summary of Court Case against Franklin
Technologies and Mid-South Adhesive Company in Calhoun County, MS.
(EPA-HQ-OAR-2002-0064-0217)
Collatz, 2003. Comment entitled ``Addition of n-Propyl-Bromide to
the Significant New Alternatives Policy (SNAP) List'' submitted by
Mark Collatz, Director of Government Relations, The Adhesive and
Sealant Council, Inc. 04-Aug-2003. (EPA-HQ-OAR-2002-0064-0066)
Confidential submission, 1998. Full citation above in ``Human
Health'' section.
CSMA, 1998. Letter with attachments from J. DiFazio, Chemical
Specialties Manufacturers Association to C. Newberg, EPA Re:
Maintaining the Current Exemption under Section 610 of the Clean Air
Act for Use of HCFC-141b in Electronic Cleaning and Aircraft
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Harper, 2005. Full citation above for ``Availability'' section.
ICF, 2006a. Full citation above for section on ``Impacts on the
atmosphere, local air quality, and other environmental impacts''.
Lake City Army Ammunition Plant, 2004. Full citation above in
``Human Health''section.
Linnell, 2003. Comments from the Electronics Industry Alliance. (IV-
D-25/EPA-HQ-OAR-2002-0064 items -0043, -0044, and -0045)
Majersik et al., 2004. Full citation above for ``Human Health''
section.
Majersik et al, 2005. Full citation above for ``Human Health''
section.
Miller, 2005. Full citation above for ``Human Health'' section.
NIOSH, 2000a. U.S. Dept. of Health and Human Services, Letter to
Marx Industries, Inc., February 1, 2000. Re: results of nPB exposure
assessment survey conducted Nov. 16-17, 1999. (A-2001-07, II-D-7)
NIOSH, 2000b. U.S. Dept. of Health and Human Services, Letter to
Custom Products Inc., December 21, 2000. Re: results of nPB exposure
assessment survey conducted Nov. 16, 2000. (HHE Report 98-0153) (A-
2001-07, II-D-8)
NIOSH, 2001. U.S. Dept. of Health and Human Services, Letter to STN
Cushion Company, March 7, 2001. Re: Results of nPB exposure
assessment survey conducted November 14, 2000. (A-2001-07, II-D-9)
NIOSH, 2002a. Full citation above in ``Human Health'' section.
NIOSH, 2002b. Full citation above in ``Human Health'' section.
NIOSH, 2003a. NIOSH Health Hazard Evaluation Report 99-
0260-2906 Marx Industries, Inc. Sawmills, NC Available online at
http://www.cdc.gov/niosh/hhe/reports/pdfs/1999-0260-2906.pdf. (EPA-
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Raymond and Ford, 2005. Full citation above for ``Human Health''
section.
U.S. EPA, 2004. U.S. EPA Solvent Market Report: The U.S. Solvent
Cleaning Industry and the Transition to Non Ozone Depleting
Substances. Prepared for U.S. Environmental Protection Agency,
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Consulting. September 2004. (EPA-HQ-OAR-2002-0064-0106)
Werner, 2003. Full citation above for ``Human Health'' section.
Williams, 2005. Full citation above for ``Availability'' section.
What other options did EPA consider?
ACGIH, 2002. Industrial Ventilation: A Manual of Recommended
Practice 23rd Edition. American Conference of Governmental
Industrial Hygienists, Cincinnati, Ohio Available online at http://www.acgih.org.
CSMA, 1999. Full citation above for ``Decisions for Each Sector and
End Use'' section.
Ensolv, 2006. Material Safety Data Sheet for Ensolv Solvents. Enviro
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ERG, 2004. Analysis of Health and Environmental Impacts of ODS
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ICF, 2006a. Full citation above for section on ``Impacts on the
atmosphere, local air quality, and other environmental impacts''.
Lake City Army Ammunition Plant, 2004. Full citation above for
``Decisions for Each Sector and End Use'' section.
Linnell, 2003. Full citation above for ``Ozone Depletion Potential
and Other Environmental Impacts'' section.
Micro Care, 2006. Web page for Micro Care Corporation on the Trigger
GripTM Dispensing System. URL at http://www.microcare.com/products/PDF/PS-05T_G.html, last update January
19, 2006. Also see http://www.microcare.com/images/PDF-CSP-Allied%20Worker%20Exposures.pdf.
NIOSH, 2000a. U.S. Dept. of Health and Human Services, Letter to
Marx Industries, Inc., February 1, 2000. Re: Results of nPB exposure
assessment survey conducted Nov. 16-17, 1999. (A-2001-07, II-D-7)
NIOSH, 2002a. NIOSH Health Hazard Evaluation Report: HETA
98-0153-2883; Custom Products, Inc.; Mooresville, NC. National
Institute for Occupational Safety and Health. November 2002.
Available online at http://www.cdc.gov/niosh/hhe/reports/pdfs/1998-0153-2883.pdf. (EPA-HQ-OAR-2002-0064-0093)
NIOSH. 2002b. NIOSH Health Hazard Evaluation Report: HETA
2000-0410-2891; STN Cushion Company; Thomasville, NC.
National Institute for Occupational Safety and Health. August 2002.
Available online at http://www.cdc.gov/niosh/hhe/reports/pdfs/2000-0410-2891.pdf. (A-2001-07, II-A-31)
NIOSH, 2003a. NIOSH Health Hazard Evaluation Report 99-
0260-2906 Marx Industries, Inc. Sawmills, NC Available online at
http://www.cdc.gov/niosh/hhe/reports/pdfs/1999-0260-2906.pdf. (EPA-
HQ-OAR-2002-0064-0094)
NIOSH, 2003b. Method 1025 for 1- and 2-Bromopropane. NIOSH Manual of
Analytical Methods, 4th Edition, March 15, 2003. (EPA-HQ-OAR-2002-
0064-0173)
NIOSH, 2003c. Method 1003 for Halogenated Hydrocarbons. NIOSH Manual
of Analytical Methods, 4th Edition, March 15, 2003. (EPA-HQ-OAR-
2002-0064-0134)
Williams, 2005. Full citation above for ``Availability'' section.
What are the anticipated costs of this regulation to the regulated
community?
U.S. EPA, 2006. Analysis of Economic Impacts of nPB Rulemaking.
2006.
Comparison of EPA's June 2003 Proposal and This Proposal
ACGIH, 2005. Full citation above for ``Human Health'' section.
CERHR, 2002a. Full citation above for ``Human Health'' section.
CERHR, 2002b. Full citation above for ``Human Health'' section.
Doull and Rozman, 2001. Derivation of an Occupational Exposure Limit
for n-Propyl Bromide, prepared by John Doull, PhD., M.D., and Karl
K. Rozman, PhD., D.A.B.T. submitted by Envirotech International,
Inc. (A-2001-07, II-D-14)
ICF, 2001. Brief Discussion of the BMD Approach: Overview of its
Purpose, Methods, Advantages, and Disadvantages. Prepared for U.S.
EPA. (A-2001-07, II-A-52)
ICF, 2002a. Full citation above for ``Human Health'' section.
ICF, 2002b. Comments on the NTP-Center for the Evaluation of Risks
to Human Reproduction, Final Report on 1-Bromopropane. Cover Letter
Dated 5/9/02. (EPA-HQ-OAR-2002-0064-0013)
ICF, 2006a. Full citation above for section on ``Impacts on the
atmosphere, local air quality, and other environmental impacts''.
Rodricks, 2002. Full citation above for ``Human Health'' section.
Rozman and Doull, 2002. Full citation above for ``Human Health''
section.
Rozman and Doull, 2005. Full citation above for ``Human Health''
section.
SLR International, 2001. Full citation above for ``Human Health''
section.
Stelljes and Wood, 2004. Full citation above for ``Human Health''
section.
Stelljes, ME. 2005. Full citation above for ``Human Health''
section.
[[Page 30207]]
TERA, 2004. Full citation above for ``Human Health'' section.
WIL, 2001. Full citation above for ``Human Health'' section.
How can I use nPB as safely as possible?
ACGIH, 2002. Full citation above for ``What other options did EPA
consider'' section.
Statutory and Executive Order Reviews
U.S. EPA, 2006. Analysis of Economic Impacts of nPB Rulemaking.
2006.
U.S. EPA, 2007. Analysis of Economic Impacts of Proposed nPB Rule
for Aerosols and Adhesives. 2007.
List of Subjects in 40 CFR Part 82
Environmental protection, Administrative practice and procedure,
Air pollution control, Reporting and recordkeeping requirements.
Dated: May 15, 2007.
Stephen L. Johnson,
Administrator.
For the reasons set out in the preamble, 40 CFR part 82 is proposed
to be amended as follows:
PART 82--PROTECTION OF STRATOSPHERIC OZONE
1. The authority citation for Part 82 continues to read as follows:
Authority: 42 U.S.C. 7414, 7601, 7671--7671q.
2. Subpart G is amended by adding Appendix S to read as follows:
Subpart G--Significant New Alternatives Policy Program
* * * * *
Appendix S to Subpart G--Substitutes Subject to Use Restrictions and
Unacceptable Substitutes
Listed in the May 30, 2007 final rule.
Aerosols--Unacceptable Substitutes
----------------------------------------------------------------------------------------------------------------
End use Substitute Decision Further information
----------------------------------------------------------------------------------------------------------------
Aerosol solvents.................. n-propyl bromide (nPB) as Unacceptable......... EPA finds unacceptable
a substitute for CFC-113, risks to human health in
HCFC-141b, and methyl this end use compared to
chloroform. other available
alternatives. nPB, also
known as 1-bromopropane,
is Number 106-94-5 in
the CAS Registry.
----------------------------------------------------------------------------------------------------------------
Adhesives, Coatings, and Inks--Substitutes That Are Acceptable Subject to Use Conditions
----------------------------------------------------------------------------------------------------------------
End use Substitute Decision Use conditions Further information
----------------------------------------------------------------------------------------------------------------
Coatings n-propyl bromide Acceptable subject Use is limited to EPA recommends the use
(nPB) as a to use conditions. coatings at facilities of personal protective
substitute for that, as of May 30, equipment, including
methyl chloroform, 2007, have provided chemical goggles,
CFC-113, and HCFC- EPA information flexible laminate
141b. demonstrating protective gloves and
acceptable workplace chemical-resistant
exposures. clothing.
EPA expects that all
users of nPB would
comply with any final
Permissible Exposure
Limit that the
Occupational Safety
and Health
Administration issues
in the future under 42
U.S.C. 7610(a).
nPB, also known as 1-
brompropane, is Number
106-94-5 in the CAS
Registry.
----------------------------------------------------------------------------------------------------------------
As of May 30, 2007, the Lake City Army Ammunition Plant is the only facility using nPB in coatings that has
provided information to EPA that meets this condition.
Adhesives, Coatings, and Inks--Unacceptable Substitutes
----------------------------------------------------------------------------------------------------------------
End use Substitute Decision Further information
----------------------------------------------------------------------------------------------------------------
Adhesives......................... n-propyl bromide (nPB) as Unacceptable......... EPA finds unacceptable
a substitute for CFC-113, risks to human health in
HCFC-141b, and methyl this end use compared to
chloroform. other available
alternatives. nPB, also
known as 1-bromopropane,
is Number 106-94-5 in
the CAS Registry.
----------------------------------------------------------------------------------------------------------------
[FR Doc. E7-9706 Filed 5-29-07; 8:45 am]
BILLING CODE 6560-50-P