[Federal Register: April 29, 2003 (Volume 68, Number 82)]
[Notices]
[Page 22704-22709]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr29ap03-89]
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DEPARTMENT OF HEALTH AND HUMAN SERVICES
Agency for Toxic Substances and Disease Registry
[ATSDR-192]
Announcement of Final Priority Data Needs for 10 Priority
Hazardous Substances
AGENCY: Agency for Toxic Substances and Disease Registry (ATSDR), U.S.
Department of Health and Human Services (HHS).
ACTION: Notice.
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SUMMARY: This Notice announces the final priority data needs for 10
priority hazardous substances (see attached Table 1) as part of the
continuing development and implementation of the ATSDR Substance-
Specific Applied Research Program (SSARP). The Notice also serves as a
continuous call for voluntary research proposals. The SSARP is
authorized by the Comprehensive Environmental Response, Compensation,
and Liability Act of 1980 (Superfund) or CERCLA, and amended by the
Superfund Amendments and Reauthorization Act of 1986 (SARA) [42 U.S.C.
9604(i)].
At the time the SSARP was initiated on October 17, 1991, a list of
priority data needs for 38 priority hazardous substances was announced
in the Federal Register (56 FR 52178). The list was subsequently
revised based on public comments and published in final form on
November 16, 1992 (57 FR 54150). In 1997, ATSDR finalized the priority
data needs for a second list of 12 substances that was subsequently
announced in the Federal Register (62 FR 40820).
[[Page 22705]]
Ten substances constitute the third list of hazardous substances
for which priority data needs have been identified by ATSDR. The 10
substances, which are included in the ATSDR Priority List of Hazardous
Substances established by ATSDR and the U.S. Environmental Protection
Agency (EPA) (66 FR 54014, October 25, 2001), are:
[sbull] asbestos
[sbull] benzidine
[sbull] chlorinated dibenzo-p-dioxins
[sbull] 1,2-dibromoethane
[sbull] 1,2-dichloroethane
[sbull] 1,1-dichloroethene
[sbull] ethylbenzene
[sbull] pentachlorophenol
[sbull] 1,1,2,2-tetrachloroethane
[sbull] total xylenes
In developing this list, ATSDR solicited input from EPA and the
National Institute of Environmental Health Sciences (NIEHS), both of
which also reviewed the draft priority data needs before they were made
available for public comment. The priority data needs were initially
announced by ATSDR in the Federal Register on August 14, 2001 (66 FR
42660). The public was invited to comment on them during a 90-day
period. ATSDR received comments from four industry groups and a
nonprofit private organization concerning programmatic and substance-
specific issues pertaining to the implementation of the research
program. ATSDR has identified several generic issues resulting from the
public comments. These issues and ATSDR's responses are presented
below. ATSDR has finalized the priority data needs for these 10
substances. Both the priority data needs documents (that provide
ATSDR's rationale for assigning priority to a data need) and the
response to public comments documents are available by requesting them
in writing from ATSDR (see ADDRESSES section of this Notice).
This Notice also serves as a continuous call for voluntary research
proposals. Private-sector organizations may volunteer to conduct
research to address specific priority data needs in this Notice by
indicating their interest through submission of a letter of intent to
ATSDR (see ADDRESSES section of this Notice). The letter should include
a brief statement that addresses the priority data need(s) to be filled
and the methods to be used. A Tri-Agency Superfund Applied Research
Committee (TASARC) comprised of scientists from ATSDR, the National
Toxicology Program (NTP), and EPA will review all submissions.
DATES: The ATSDR voluntary research program is a continuous program,
and private-sector organizations can volunteer to fill identified data
needs from now until that time when ATSDR announces that other research
has been initiated for a specific data need.
ADDRESSES: Private-sector organizations interested in volunteering to
conduct research to fill identified priority data needs should write to
Dr. William Cibulas, Chief, Research Implementation Branch, Division of
Toxicology, ATSDR, 1600 Clifton Road, NE., Mailstop E-29, Atlanta,
Georgia 30333, or e-mail Dr. Cibulas at wcibulas@cdc.gov. Requests for
the priority data needs documents and response to public comments
documents should be addressed similarly.
FOR FURTHER INFORMATION CONTACT: Dr. William Cibulas, Chief, Research
Implementation Branch, Division of Toxicology, ATSDR, 1600 Clifton
Road, NE., Mailstop E-29, Atlanta, Georgia 30333, telephone (404) 498-
0140.
SUPPLEMENTARY INFORMATION:
Background
The Comprehensive Environmental Response, Compensation, and
Liability Act of 1980 (Superfund) or CERCLA, as amended by the
Superfund Amendments and Reauthorization Act of 1986 (SARA) [42 U.S.C.
9604(i)], requires that ATSDR (1) develop jointly with EPA a list of
hazardous substances found at National Priorities List (NPL) sites (in
order of priority), (2) prepare toxicological profiles of these
substances, and (3) assure the initiation of a research program to
address identified priority data needs associated with the substances.
The primary purpose of this research program is to provide the
public and scientific communities with answers to some of the key
questions regarding health effects and exposure to these substances.
For ATSDR, this research program supplies necessary information to
improve the database to conduct public health assessments. This link
between research and public health assessments, and the process for
distilling priority data needs for ranked hazardous substances from
data needs identified in associated ATSDR toxicological profiles, are
described in the ATSDR ``Decision Guide for Identifying Substance-
Specific Data Needs Related to Toxicological Profiles'' (54 FR 37618,
September 11, 1989).
At the time the Substance-Specific Applied Research Program (SSARP)
was initiated on October 17, 1991, a list of priority data needs for 38
priority hazardous substances was announced in the Federal Register (56
FR 52178). The list was subsequently revised based on public comments
and published in final form on November 16, 1992 (57 FR 54150). In
1997, ATSDR finalized the priority data needs for a second list of 12
substances (62 FR 40820). Currently, a total of 190 priority data needs
have been identified for these 50 substances as described in ``Update
on the Status of the Superfund Substance-Specific Applied Research
Program'' (67 FR 4836, January 31, 2002).
In 2001, ATSDR identified the priority data needs for 10 additional
hazardous substances and announced them in draft form on August 14,
2001 (66 FR 42660). The public was invited to comment on the draft
priority data needs during a 90-day period. The agency responded to all
the comments and revised the priority data needs, as needed.
ATSDR's Response to Public Comments
As mentioned in the SUMMARY section of this Notice, ATSDR has
identified several generic public comments on the priority data needs
for the 10 hazardous substances. These comments and ATSDR's responses
are presented below.
Comment: Request for ATSDR to clarify if and how any further
testing requests or regulatory requirements for testing will be subject
to public scrutiny.
Response: ATSDR published the draft priority data needs (PDNs) in
the August 14, 2001, Federal Register Notice with a public comment
period of 90 days. A final list of PDNs will be published following
completion of deliberations on the comments received. In the event that
a study is to be conducted via the mechanisms described in the Federal
Register Notice--e.g., industry-sponsored voluntary research, or
university-based research supported by the Comprehensive Environmental
Response, Compensation, and Liability Act (CERCLA) funds--the study
protocol and final report will be reviewed by ATSDR's external peer
reviewers, and all documents related to the project will be made
available for public inspection at ATSDR. Also, any testing that
results from coordination with the U.S. Environmental Protection Agency
(EPA) and development of a Toxic Substances Control Act (TSCA) test
rule will be subjected to a public comment period consistent with EPA
guidelines. ATSDR publishes an update of its Substance-Specific Applied
Research Program in the Federal Register every three years.
Comment: Concern that the Federal Register Notice makes no mention
of the use of in vitro methodologies.
[[Page 22706]]
Response: ATSDR agrees with the commenter and will more explicitly
state its support of innovative methodologies, including non-animal
testing, in future notices about the agency's Substance-Specific
Applied Research Program. In a recently published Federal Register
Notice updating the status of this research program (67 FR 4836,
January 31, 2002), the agency stated that ``ATSDR encourages the use of
in vitro assessment methods and other innovative tools for filling
priority data needs. For example, the agency believes that
physiologically based pharmacokinetic (PBPK) modeling could serve as a
valuable tool in predicting across route similarities (or differences)
in toxicological responses to hazardous substances. Therefore, on a
case-by-case basis, a priority data need can be filled using existing
data and modeling.'' In fact, in the ATSDR voluntary research program
(a component of ATSDR's Substance-Specific Applied Research Program),
the Halogenated Solvents Industry Alliance, Inc. (HSIA) has conducted
studies to fill ATSDR's priority data needs for volatile organic
compounds using PBPK modeling.
Also, ATSDR is a member of the National Toxicology Program's (NTP)
Interagency Coordinating Committee on the Validation of Alternative
Methods (ICCVAM) and supports development, validation, and acceptance
of alternative toxicological test methods that reduce, refine, and
replace the use of animals, as appropriate. Through its participation
on ICCVAM, ATSDR keeps informed of reliable and valid alternative test
methods.
Comment: Request for ATSDR to withdraw the endocrine disruption and
developmental neurotoxicity priority data needs because there are no
validated animal tests for these end points.
Response: ATSDR has identified a priority data need to assess the
potential for pentachlorophenol to affect endocrine functions and for
reproductive studies with ethylbenzene. As a result of the agency's
evaluation of the comments received from the Pentachlorophenol Task
Force, the priority data need for in vivo endocrine disruptor studies
via oral exposure to pentachlorophenol has been changed. This change
resulted because the Pentachlorophenol Task Force submitted a recently
completed two-generation reproduction study that was subsequently
published in a peer-reviewed journal. ATSDR accepted the data and no
longer assigned priority to this research need. With regard to
ethylbenzene, no new information has been available to ATSDR, and the
priority data need for ethylbenzene remains unchanged. For the same
reason, ATSDR will not withdraw the priority data need for
developmental neurotoxicity testing for xylenes.
ATSDR is a nonregulatory, science-based agency. The agency is
mandated (in consultation with EPA and agencies and programs of the
Public Health Service) to assess whether adequate information on the
health effects of hazardous substances is available. Where adequate
information is not available, ATSDR, in cooperation with NTP, is
required to assure the initiation of a research program to determine
these health effects. Toward this end, ATSDR established the Tri-Agency
Superfund Applied Research Committee (TASARC) consisting of scientists
from ATSDR, EPA, and NTP to collaborate on mutual research needs and to
discuss issues relevant to the proposed studies, such as the validation
status and regulatory acceptance of proposed test methods. It should be
noted that ATSDR does not develop testing guidelines or methodologies
for toxicological research.
Consistent with the CERCLA mandate, on August 14, 2001, ATSDR
published a Federal Register Notice announcing the identification of
key research needs for 10 additional hazardous substances, and provided
a rationale for these determinations in support documents (i.e.,
priority data needs documents are available for all 10 substances).
However, the agency did not identify, propose, or discuss specific test
methods to be used to fill the data needs (66 FR 42660). There are no
universally agreed upon and validated animal tests to fill the priority
data needs for endocrine disruption and developmental neurotoxicity,
similar to a lack of such tests to fill the priority data needs for
biomarker and mechanistic studies. Consequently, these studies require
basic research or other mechanisms to satisfy the information need.
Therefore, in filling these research needs, ATSDR does not specify or
require that certain (animal) tests be performed. Instead, ATSDR
remains open to receiving scientific information to fill these research
needs from a variety of sources, including organizations that may
propose innovative methodologies involving non-animal tests. In such
cases, the agency generally consults with programmatic experts at the
National Institute of Environmental Health Sciences (NIEHS) and EPA,
and outside scientists to advise the agency on the appropriateness and
validation status of the proposed methods for filling its research
needs. Also, ATSDR is working closely with organizations such as NTP's
Interagency Coordinating Committee on the Validation of Alternative
Methods (ICCVAM) to stay abreast of testing validation issues. In fact,
ATSDR is participating fully in this committee's effort to validate a
battery of in vivo and in vitro tests to assess endocrine disruption.
Comment: Concern about ATSDR calling for more lethal poisoning
tests on animals and request that ATSDR withdraw its proposal to
conduct more acute toxicity tests on animals for these 10 substances.
Response: The ATSDR Substance-Specific Applied Research Program is
designed to address the most important public health research needs for
citizens exposed to hazardous environmental substances. ATSDR has not
required, and will not require, LD50 or other lethality data
as an adjunct to the process. However, ATSDR often requests short-term
(acute) toxicity data on non-lethal end points in order to determine
the agency's health guidance values (minimal risk levels [MRLs]) for
citizens who are possibly exposed to chemicals for durations of 14 days
or less.
If the agency considers the existing acute duration (14 days or
less) database to be inadequate for fully characterizing the short-term
toxicity of a particular hazardous substance, it will identify the need
to conduct additional [inhalation and/or oral] studies for determining
critical targets and establishing dose-response relationships.
Comment: Concern that ATSDR's requests for more information ignore
sophisticated analyses that can be conducted using, for example,
structure-activity relationships (SAR).
Response: In evaluating the need for additional data on a
particular end point and assigning priority to data needs for the 10
substances, ATSDR first reviewed the available chemical-specific data
for a given end point. In addition, ATSDR conducted SAR analyses on
these substances and used the information in a strength-of-evidence
approach to determine the need to assign priority for the missing
information.
Comment: Request that ATSDR defer final assessment of its priority
data needs until the industry groups have completed their work under
EPA's voluntary children's chemical evaluation program (VCCEP), the
hazardous air pollutants (HAPs) test rule, and an enforceable consent
agreement (for 1,2-dichloroethane) among others.
[[Page 22707]]
Response: ATSDR has developed a process for assigning priority to
data needs identified in the agency's toxicological profiles for
hazardous substances. Specifically, the process for prioritizing the
data needs is based on a logical scientific approach as described in
ATSDR's Decision Guide (54 FR 37618, September 11, 1989). The
identified priority data needs (PDNs) are then subjected to public and
peer review. Currently, ATSDR considers these PDNs to be the most
critical research needs for these hazardous substances. However, the
agency will continue to evaluate new data for these substances obtained
through additional testings, e.g., industry groups' participation in
other federal agencies' programs. Specifically, ATSDR is working
closely with EPA on these activities where we have identified
overlapping research priorities. Therefore, the status of these PDNs
may change in the future. In this current Federal Register Notice
announcing the final list of PDNs, ATSDR states that these PDNs remain
on the agency's list but that they may potentially be filled by
individual industry groups working under specific EPA programs (see
Table 1).
In summary, as a result of the agency's evaluation of all the
public comments received for the 10 hazardous substances, two priority
data needs were changed. Specifically, in vivo endocrine disruptor
studies via oral exposure and multigeneration reproduction study
involving multiple matings and examining male and female fertility via
oral exposure were initially identified as priority data needs for
pentachlorophenol. During the public comment period, ATSDR received
from the Pentachlorophenol Task Force a recently completed two-
generation reproduction study that was subsequently published in a
peer-reviewed journal. ATSDR accepted the data and no longer assigned
priority to these research needs. No changes were made to the priority
data needs for the other nine substances as a result of the public
comments.
Implementation of Substance-Specific Applied Research Program
Regarding the implementation of the SSARP, in section 104(i)(5)(D),
CERCLA states that it is the sense of Congress that the costs for
conducting this research program be borne by the manufacturers and
processors of the hazardous substances under the Toxic Substances
Control Act of 1976 (TSCA) and by registrants under the Federal
Insecticide, Fungicide, and Rodenticide Act of 1972 (FIFRA), or by cost
recovery from responsible parties under CERCLA. To execute this
statutory intent, ATSDR developed a plan whereby parts of the SSARP are
being conducted via regulatory mechanisms (TSCA/FIFRA), private-sector
voluntarism, and through the direct use of CERCLA funds. CERCLA also
requires that ATSDR consider recommendations of the Interagency Testing
Committee (ITC), established under Section 4(e) of TSCA, on the types
of research to be done. ATSDR actively participates on this committee;
however, none of the proposed 10 substances are now on the ITC priority
testing list.
The priority data needs identified in this Notice reflect the
opinion of the agency, in consultation with other federal programs, of
the research needed pursuant to ATSDR's authority under CERCLA. They do
not represent the priority data needs for any other program. Consistent
with section 104(i)(12) of CERCLA as amended (42 U.S.C. 9604(i)(12)),
nothing in this research program shall be construed to delay or
otherwise affect or impair the authority of the President, the
Administrator of ATSDR, or the Administrator of EPA to exercise any
authority regarding any other provision of law, including the Toxic
Substances Control Act of 1976 (TSCA) and the Federal Insecticide,
Fungicide, and Rodenticide Act of 1972 (FIFRA), or the response and
abatement authorities of CERCLA. In developing this research program,
ATSDR has worked with other federal programs to determine common
substance-specific data needs, as well as mechanisms to implement
research that may include authorities under TSCA and FIFRA, private-
sector voluntarism, or the direct use of CERCLA funds.
When deciding the type of research that should be done, ATSDR
considers the recommendations of the Interagency Testing Committee
established under section 4(e) of TSCA. Federally funded projects that
collect information from 10 or more respondents and that are funded by
cooperative agreements are subject to review by the Office of
Management and Budget (OMB) under the Paperwork Reduction Act. If the
proposed project involves research on human subjects, the applicants
must comply with Department of Health and Human Services regulations
(45 CFR part 46) regarding the protection of human subjects. Assurance
must be provided that the project will be subject to initial and
continuing review by the appropriate institutional review committees.
Overall, data generated from this research program will lend support to
others conducting human health assessments involving these 10
substances by providing additional scientific information for the risk
assessment process.
Substance-Specific Priority Data Needs
The final priority data needs are identified in Table 1. Unique
identification numbers (37A through 46G) are assigned to the priority
data needs for this list of 10 priority hazardous substances; the
priority data needs for the first 50 substances were assigned
identification numbers 1A through 36E (67 FR 4836). Parts of the
proposed research are unique to CERCLA and may be most appropriately
addressed by ATSDR programs as follows.
ATSDR's responsibility as a public health agency addressing
environmental health issues is, when appropriate, to collect human data
to validate substance-specific exposure and toxicity assumptions. ATSDR
will obtain this information by conducting exposure and health effects
studies, and by establishing and using substance-specific subregistries
of people enrolled in the agency's National Exposure Registry who are
potentially exposed to these substances. When a subregistry or a human
exposure study is identified as a priority data need, the responsible
ATSDR program will determine its feasibility, which depends on
identifying appropriate populations and funding.
In addition, the need to collect, evaluate, and interpret
environmental data from contaminated media around hazardous waste sites
remains a priority data need for all 10 priority hazardous substances
ATSDR has identified for this third set.
However, some of this information has already been collected
through individual state programs and the EPA's CERCLA activities;
therefore, ATSDR will evaluate the extant information from these
programs to better characterize the need for additional site-specific
information.
ATSDR acknowledges that the conduct of human studies to determine
possible links between exposure to hazardous substances and human
health effects may be accomplished through mechanisms other than agency
programs. We encourage private-sector organizations and other
governmental programs to use ATSDR's priority data needs to plan their
research activities, including identifying appropriate
[[Page 22708]]
populations and conducting studies to answer specific human health
questions.
Dated: April 10, 2003.
Georgi Jones,
Director, Office of Policy and External Affairs, Agency for Toxic
Substances and Disease Registry.
Table 1.--Final Substance--Specific Priority Data Needs (PDNs) for Third
Set of 10 Priority Hazardous Substances
------------------------------------------------------------------------
Substance PDN ID Priority data needs
------------------------------------------------------------------------
Asbestos.......................... 37A Epidemiologic studies of
individuals
occupationally exposed to
asbestos levels lower
than those experienced
before the institution of
current occupational
standards governing the
use of asbestos, but
higher than current
levels in the general
population. These studies
should be performed in
conjunction with the
immunotoxicity studies.
37B Immunotoxicity studies of
individuals
occupationally exposed to
asbestos.
37C Development of human and
rat lung retention models
to aid in extrapolating
between rat and human
data.
37D Improved analytical
methods for screening
samples and determining
the chemical structure of
asbestos fibers. Also,
techniques are needed to
normalize studies in
which different
analytical methods were
employed.
37E Exposure levels, fiber
size distribution, and
asbestos fiber type in
areas with natural
geologic deposits of
friable asbestos and at
hazardous waste sites.
Also, techniques for
estimating air levels of
asbestos from soil
concentrations and
activity scenarios.
37F Exposure levels in humans
living near hazardous
waste sites and in other
populations, such as
humans living in areas
with naturally high
levels of friable
asbestos.
37G Potential candidate for
subregistry of exposed
persons.
Benzidine......................... 38A Dose-response data for
acute- and intermediate-
duration exposure via the
oral route (the study of
intermediate-duration
exposure should include
evaluation of
reproductive and
endocrine organ
histopathology, lymphoid
tissues histopathology as
well as examination of
relevant blood
components, and nervous
system histopathology).
38B Exposure levels in humans
living near hazardous
waste sites.
38C Exposure levels in
children.
38D Potential candidate for
subregistry of exposed
persons.
Chlorinated dibenzo-p-dioxins 39A Studies via oral exposure
(CDDs). designed to assess
childhood susceptibility.
39B Comparative toxicokinetic
studies examining the
relative absorption of
CDDs across exposure
routes and the relative
contribution of each
exposure route to total
body burdens.
39C Exposure levels in humans
living near hazardous
waste sites.
39D Exposure levels in
children.
1,2-Dibromoethane................. 40A Dose-response data in
animals for acute- and
intermediate-duration
exposure by the oral
route (the study of
intermediate-duration
exposure should include
evaluation of
neuropathology and
observation for overt
signs of neurotoxicity).
40B Multigeneration
reproductive toxicity
studies via oral
exposure.
40C Developmental toxicity
studies via oral
exposure.
40D Immunotoxicity battery
studies via oral
exposure.
40E Exposure levels in humans
living near hazardous
waste sites and in other
populations, such as
workers exposed to 1,2-
dibromoethane.
40F Exposure levels in
children.
40G Potential candidate for
subregistry of exposed
persons.
1,2-Dichloroethane[hairsp]*....... 41A Dose-response data in
animals for acute-
duration (14-day)
exposure by the
inhalation route,
including a comparison of
young and adult animals.
41B Dose-response data in
animals for acute-
duration (14-day)
exposure by the oral
route, including a
comparison of young and
adult animals.
41C Dose-response data in
animals for intermediate-
duration exposure by the
inhalation route (the
study should be performed
in conjunction with the
neurotoxicology battery
of tests).
41D Neurotoxicology battery of
tests following
inhalation exposure.
41E Neurotoxicology battery of
tests following oral
exposure.
41F Dose-response data in
animals for chronic-
duration exposure by the
oral route.
41G Developmental toxicity
data for inhalation
exposure (assessment of
developmental
cardiotoxicity and
neurotoxicity).
41H Developmental toxicity
data for oral exposure
(assessment of
developmental
cardiotoxicity and
neurotoxicity).
41I Additional analyses and
studies for comparative
toxicokinetics across
species, ages, routes,
and durations.
41J Children's susceptibility.
41K Exposure levels in humans
living near hazardous
waste sites.
41L Exposure levels in
children.
41M Potential candidate for
subregistry of exposed
persons.
1,1-Dichloroethene[hairsp]*....... 42A Dose-response data in
animals for acute-
duration exposure by the
inhalation route.
42B Dose-response data in
animals for chronic-
duration exposure by the
inhalation route.
42C Dose-response data in
animals for acute- and
intermediate-duration
exposure by the oral
route.
42D Carcinogenicity studies in
two species following
inhalation exposure.
[[Page 22709]]
42E Reproductive toxicity
studies assessing male
and female end points
following inhalation
exposure.
42F Developmental toxicity
studies following oral
exposure.
42G Immunotoxicology battery
of tests following oral
exposure.
42H Battery of neurobehavioral
tests following
inhalation exposure.
42I Children's susceptibility.
42J Exposure levels in humans
living near hazardous
waste sites.
42K Exposure levels in
children.
42L Potential candidate for
subregistry of exposed
persons.
Ethylbenzene[hairsp]*............. 43A Dose-response data for
acute-duration exposure
by the inhalation route.
43B Dose-response data for
chronic-duration exposure
by the inhalation route.
43C Dose-response data for
acute- and intermediate-
duration exposure by the
oral route; the study of
intermediate-duration
exposure should include
an evaluation of clinical
signs of neurotoxicity
and histopathology of
reproductive organs,
endocrine glands, and
nervous system.
43D Multigeneration toxicity
study examining
reproductive end points
and indicators of
endocrine disruption
following inhalation
exposure.
43E Two-species developmental
study with continued
assessment of offspring
during postnatal
development following
oral exposure.
43F Studies for comparative
toxicokinetics.
43G Exposure levels in humans
living near hazardous
waste sites.
43H Exposure levels in
children.
43I Potential candidate for
subregistry of exposed
persons.
Pentachlorophenol................. 44A Comparative toxicokinetic
studies.
44B Exposure levels in humans
living near hazardous
waste sites.
44C Exposure levels in
children through play
activities near
contaminated
environmental media.
44D Potential candidate for
subregistry of exposed
persons.
1,1,2,2-Tetrachloroethane......... 45A Two-species developmental
toxicity study by the
oral route.
45B Immunotoxicity battery
following oral exposure.
45C Mammalian in vivo
genotoxicity assays.
45D Exposure levels in humans
living near hazardous
waste sites.
45E Exposure levels in
children.
45F Potential candidate for
subregistry of exposed
persons.
Total xylenes..................... 46A Dose-response data for
chronic-duration exposure
by the oral route. This
study should be done in
conjunction with the
neurotoxicology battery
of tests.
46B Neurotoxicology battery of
tests following oral
exposure.
46C Two-generation
reproductive study
following oral exposure.
46D Developmental toxicity
study that includes
neurodevelopmental end
points following oral
exposure.
46E Exposure levels in humans
living near hazardous
waste sites.
46F Exposure levels in
children.
46G Potential candidate for
subregistry of exposed
persons.
------------------------------------------------------------------------
* Some of the toxicity priority data needs may potentially be filled by
individual industry groups working under specific EPA programs.
[FR Doc. 03-9300 Filed 4-28-03; 8:45 am]
BILLING CODE 4163-70-P