[Federal Register: March 12, 2003 (Volume 68, Number 48)]
[Notices]
[Page 11850-11855]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr12mr03-93]
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ENVIRONMENTAL PROTECTION AGENCY
[OPP-2003-0022; FRL-7295-9]
Dimethenamid; Notice of Filing a Pesticide Petition to Establish
a Tolerance for a Certain Pesticide Chemical in or on Food
AGENCY: Environmental Protection Agency (EPA).
ACTION: Notice.
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SUMMARY: This notice announces the initial filing of a pesticide
petition proposing the establishment of regulations for residues of a
certain pesticide chemical in or on various food commodities.
DATES: Comments, identified by docket ID number OPP-2003-0022, must be
received on or before April 11, 2003.
ADDRESSES: Comments may be submitted electronically, by mail, or
through hand delivery/courier. Follow the detailed instructions as
provided in Unit I. of the SUPPLEMENTARY INFORMATION.
FOR FURTHER INFORMATION CONTACT: Sidney Jackson, Registration Division
(7505C), Office of Pesticide Programs, Environmental Protection Agency,
1200 Pennsylvania Ave., NW., Washington, DC 20460-0001; telephone
number: (703) 305-7610; e-mail address: jackson.sidney@epa.gov.
SUPPLEMENTARY INFORMATION:
I. General Information
A. Does this Action Apply to Me?
You may be potentially affected by this action if you are an
agricultural producer, food manufacturer, or pesticide manufacturer.
Potentially affected entities may include, but are not limited to:
[sbull] Industry (NAICS 111), e.g., Crop production.
[sbull] Industry (NAICS 112), e.g., Animal production.
[sbull] Industry (NAICS 311), e.g., Food manufacturing.
[sbull] Industry (NAICS 32532), e.g., Pesticide manufacturing.
This listing is not intended to be exhaustive, but rather provides
a guide for readers regarding entities likely to be affected by this
action. Other types of entities not listed in this unit could also be
affected. The North American Industrial Classification System (NAICS)
codes have been provided to assist you and others in determining
whether this action might apply to certain entities. To determine
whether you or your business may be affected by this action, you should
carefully examine the applicability provisions in Unit I.A. If you have
any questions regarding the applicability of this action to a
particular entity, consult the person listed under FOR FURTHER
INFORMATION CONTACT.
B. How Can I Get Copies of this Document and Other Related Information?
1. Docket. EPA has established an official public docket for this
action under docket identification (ID) number OPP-2003-0022. The
official public docket consists of the documents specifically
referenced in this action, any public comments received, and other
information related to this action. Although a part of the official
docket, the public docket does not include Confidential Business
Information (CBI) or other information whose disclosure is restricted
by statute. The official public docket is the collection of materials
that is available for public viewing at the Public Information and
Records Integrity Branch (PIRIB), Rm. 119, Crystal Mall 2,
1921 Jefferson Davis Hwy., Arlington, VA. This docket facility is open
from 8:30 a.m. to 4 p.m., Monday through Friday, excluding legal
holidays. The docket telephone number is (703) 305-5805.
2. Electronic access. You may access this Federal Register document
[[Page 11851]]
electronically through the EPA Internet under the ``Federal Register''
listings at http://www.epa.gov/fedrgstr/.
An electronic version of the public docket is available through
EPA's electronic public docket and comment system, EPA Dockets. You may
use EPA Dockets at http://www.epa.gov/edocket/ to submit or view public
use EPA Dockets at http://www.epa.gov/edocket/ to submit or view public
comments, access the index listing of the contents of the official
public docket, and to access those documents in the public docket that
are available electronically. Although not all docket materials may be
available electronically, you may still access any of the publicly
available docket materials through the docket facility identified in
Unit I.B.1. Once in the system, select ``search,'' then key in the
appropriate docket ID number.
Certain types of information will not be placed in the EPA Dockets.
Information claimed as CBI and other information whose disclosure is
restricted by statute, which is not included in the official public
docket, will not be available for public viewing in EPA's electronic
public docket. EPA's policy is that copyrighted material will not be
placed in EPA's electronic public docket but will be available only in
printed, paper form in the official public docket. To the extent
feasible, publicly available docket materials will be made available in
EPA's electronic public docket. When a document is selected from the
index list in EPA Dockets, the system will identify whether the
document is available for viewing in EPA's electronic public docket.
Although not all docket materials may be available electronically, you
may still access any of the publicly available docket materials through
the docket facility identified in Unit I.B. EPA intends to work towards
providing electronic access to all of the publicly available docket
materials through EPA's electronic public docket.
For public commenters, it is important to note that EPA's policy is
that public comments, whether submitted electronically or in paper,
will be made available for public viewing in EPA's electronic public
docket as EPA receives them and without change, unless the comment
contains copyrighted material, CBI, or other information whose
disclosure is restricted by statute. When EPA identifies a comment
containing copyrighted material, EPA will provide a reference to that
material in the version of the comment that is placed in EPA's
electronic public docket. The entire printed comment, including the
copyrighted material, will be available in the public docket.
Public comments submitted on computer disks that are mailed or
delivered to the docket will be transferred to EPA's electronic public
docket. Public comments that are mailed or delivered to the docket will
be scanned and placed in EPA's electronic public docket. Where
practical, physical objects will be photographed, and the photograph
will be placed in EPA's electronic public docket along with a brief
description written by the docket staff.
C. How and To Whom Do I Submit Comments?
You may submit comments electronically, by mail, or through hand
delivery/courier. To ensure proper receipt by EPA, identify the
appropriate docket ID number in the subject line on the first page of
your comment. Please ensure that your comments are submitted within the
specified comment period. Comments received after the close of the
comment period will be marked ``late.'' EPA is not required to consider
these late comments. If you wish to submit CBI or information that is
otherwise protected by statute, please follow the instructions in Unit
I.D. Do not use EPA Dockets or e-mail to submit CBI or information
protected by statute.
1. Electronically. If you submit an electronic comment as
prescribed in this unit, EPA recommends that you include your name,
mailing address, and an e-mail address or other contact information in
the body of your comment. Also include this contact information on the
outside of any disk or CD ROM you submit, and in any cover letter
accompanying the disk or CD ROM. This ensures that you can be
identified as the submitter of the comment and allows EPA to contact
you in case EPA cannot read your comment due to technical difficulties
or needs further information on the substance of your comment. EPA's
policy is that EPA will not edit your comment, and any identifying or
contact information provided in the body of a comment will be included
as part of the comment that is placed in the official public docket,
and made available in EPA's electronic public docket. 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.
i. EPA Dockets. Your use of EPA's electronic public docket to
submit comments to EPA electronically is EPA's preferred method for
receiving comments. Go directly to EPA Dockets at http://www.epa.gov/
edocket
, and follow the online instructions for submitting comments.
Once in the system, select ``search,'' and then key in docket ID number
OPP-2003-0022. The system is an ``anonymous access'' system, which
means EPA will not know your identity, e-mail address, or other contact
information unless you provide it in the body of your comment.
ii. E-mail. Comments may be sent by e-mail to opp-docket@epa.gov,
Attention: Docket ID Number OPP-2003-0022. In contrast to EPA's
electronic public docket, EPA's e-mail system is not an ``anonymous
access'' system. If you send an e-mail comment directly to the docket
without going through EPA's electronic public docket, EPA's e-mail
system automatically captures your e-mail address. E-mail addresses
that are automatically captured by EPA's e-mail system are included as
part of the comment that is placed in the official public docket, and
made available in EPA's electronic public docket.
iii. Disk or CD ROM. You may submit comments on a disk or CD ROM
that you mail to the mailing address identified in Unit I.C.2. These
electronic submissions will be accepted in WordPerfect or ASCII file
format. Avoid the use of special characters and any form of encryption.
2. By mail. Send your comments to: Public Information and Records
Integrity Branch (PIRIB) (7502C), Office of Pesticide Programs (OPP),
Environmental Protection Agency, 1200 Pennsylvania Ave., NW.,
Washington, DC 20460-0001, Attention: Docket ID Number OPP-2003-0022.
3. By hand delivery or courier. Deliver your comments to: Public
Information and Records Integrity Branch (PIRIB), Office of Pesticide
Programs (OPP), Environmental Protection Agency, Rm. 119, Crystal Mall
2, 1921 Jefferson Davis Hwy., Arlington, VA, Attention: Docket
ID Number OPP-2003-0022. Such deliveries are only accepted during the
docket's normal hours of operation as identified in Unit I.B.1.
D. How Should I Submit CBI To the Agency?
Do not submit information that you consider to be CBI
electronically through EPA's electronic public docket or by e-mail. You
may claim information that you submit to EPA as CBI by marking any part
or all of that information as CBI (if you submit CBI on disk or CD ROM,
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 CBI). Information so marked will not be disclosed except in
accordance with procedures set forth in 40 CFR part 2.
[[Page 11852]]
In addition to one complete version of the comment that includes
any 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 and EPA's electronic public docket. If you submit
the copy that does not contain CBI on disk or CD ROM, mark the outside
of the disk or CD ROM clearly that it does not contain CBI. Information
not marked as CBI will be included in the public docket and EPA's
electronic public docket without prior notice. If you have any
questions about CBI or the procedures for claiming CBI, please consult
the person listed under FOR FURTHER INFORMATION CONTACT.
E. What Should I Consider as I Prepare My Comments for EPA?
You may find the following suggestions helpful for preparing your
comments:
1. Explain your views as clearly as possible.
2. Describe any assumptions that you used.
3. Provide copies of any technical information and/or data you used
that support your views.
4. If you estimate potential burden or costs, explain how you
arrived at the estimate that you provide.
5. Provide specific examples to illustrate your concerns.
6. Make sure to submit your comments by the deadline in this
notice.
7. To ensure proper receipt by EPA, be sure to identify the docket
ID number assigned to this action in the subject line on the first page
of your response. You may also provide the name, date, and Federal
Register citation.
II. What Action is the Agency Taking?
EPA has received a pesticide petition as follows proposing the
establishment and/or amendment of regulations for residues of a certain
pesticide chemical in or on various food commodities under section 408
of the Federal Food, Drug, and Cosmetic Act (FFDCA), 21 U.S.C. 346a.
EPA has determined that this petition contains data or information
regarding the elements set forth in FFDCA section 408(d)(2); however,
EPA has not fully evaluated the sufficiency of the submitted data at
this time or whether the data support granting of the petition.
Additional data may be needed before EPA rules on the petition.
List of Subjects
Environmental protection, Agricultural commodities, Feed additives,
Food additives, Pesticides and pests, Reporting and recordkeeping
requirements.
Dated: March 4, 2003.
Debra Edwards,
Acting Director, Registration Division, Office of Pesticide Programs.
Summary of Petition
The petitioner summary of the pesticide petition is printed below
as required by FFDCA section 408(d)(3). The summary of the petition was
prepared by the petitioner and represents the view of the petitioner.
The petition summary announces the availability of a description of the
analytical methods available to EPA for the detection and measurement
of the pesticide chemical residues or an explanation of why no such
method is needed.
PP 0E6196
EPA has received a pesticide petition (PP 0E6196) from the
Interregional Research Project No. 4 (IR-4), Technology Centre of New
Jersey, Rutgers, the State University of New Jersey, 681 U.S. Highway
1 South, North Brunswick, NJ 08902-3390 proposing, pursuant to
section 408(d) of the FFDCA, 21 U.S.C. 346a(d), to amend 40 CFR part
180.464 by establishing tolerances for residues of dimethenamid, (R,S)-
2-chloro-N-[(1-methyl-2-methoxy) ethyl]-N-(2,4-dimethyl-thien-3-yl)-
acetamide in or on the raw agricultural commodities beet, garden, roots
at 0.01 parts per million (ppm); beet, garden, tops at 0.01 ppm; beet,
sugar, roots at 0.01 ppm; beet, sugar, tops at 0.01 ppm; garlic, dry
bulb at 0.01 ppm; horseradish at 0.01 ppm; onion, dry bulb at 0.01 ppm,
shallot, dry bulb at 0.01 ppm; and tuberous and corm vegetables
subgroup (Crop group 1C) at 0.01 ppm. EPA has determined that the
petition contains data or information regarding the elements set forth
in section 408(d)(2) of the FFDCA; however, EPA has not fully evaluated
the sufficiency of the submitted data at this time or whether the data
supports granting of the petition. Additional data may be needed before
EPA rules on the petition. This petition summary was prepared by the
registrant, BASF Corporation, P.O. Box 13528, Research Triangle Park,
NC 27709-3528.
A. Residue Chemistry
1. Plant and animal metabolism. BASF Corporation notes that
metabolism in plants and animals is understood.
2. Analytical method. The proposed analytical method uses
extraction and clean-up followed by quantification with capillary
column gas chromatography (GC) using thermionic nitrogen specific
detector. A GC/mass spectrocopy (MS) method for identification is also
available. This method is not selective towards the dimethenamid isomer
and is therefore valid for residues from both dimethenamid and the
enriched dimethenamid-P. Tolerances are proposed based on a non-isomer
specific basis.
3. Magnitude of residues. For onion, magnitude of the residue data
are based on applications with dimethenamid. Residue trials were
conducted at 8 locations in California, Michigan, New York, Oregon,
Texas, Washington, and Wisconsin. Treatments were made at 1.5 lbs
active ingredient/acre (ai/A) 30 or 45 days before harvest. No residues
above the limit of quantitation (LOQ) of 0.01 ppm were detected in dry
bulb onion. Residue data from dry bulb onion will be used as surrogate
data for dry bulb garlic and shallots.
For sugar beet, magnitude of the residue data are based on
dimethenamid-P applications to sugar beet at 0.98 lb ai/A.
Dimethenamid-P is the biologically active isomer from the racemic
dimethenamid mixture. The method measures both dimethenamid and
dimethenamid-P, so the sugar beet residue determinations for
dimethenamid-P are considered representative of the proposed treatments
with dimethenamid. No residues were detected in sugar beet roots or
tops from a testing program conducted in 12 locations across 8 states.
Data from processing studies indicate that no residues are detected in
the roots even at exaggerated rates of 3.15 lbs ai/A. The limit of
quantitation is 0.01 ppm. The sugar beet trials also support the
tolerances for table beet.
For the tuberous and corm vegetable subgroup, magnitude of the
residue data for potatoes are based on applications with dimethenamid-
P. Residue trials were conducted at 17 locations in California,
Colorado, Florida, Idaho, Michigan, New Jersey, North Carolina, Oregon,
Pennsylvania, Washington, and Wisconsin. Treatments were made at 1.25
lbs ai/A 40 days before harvest. No residues above the LOQ of 0.01 ppm
were detected in potato tubers. Data from processing studies indicate
that no residues are detected in the tubers even at exaggerated rates
of 12.5 lbs ai/A. Residue data from potato tubers will be used as
surrogate data for horseradish.
BASF believes that due to the low levels of residue in the RAC's,
tolerances in animals are not required.
[[Page 11853]]
B. Toxicological Profile
1. Acute toxicity. Based on available acute toxicity data,
dimethenamid and dimethenamid-P do not pose an acute dietary risk. The
acute toxicity studies place both technical materials in acute toxicity
category II for acute oral; in acute toxicity category III for acute
dermal, inhalation, and eye; and in acute toxicity category IV for
dermal irritation. The technical materials are a positive skin
sensitizer.
2. Genotoxicity. The following testing was performed with
dimethenamid for genotoxicity. A modified ames test: Negative; in vitro
CHO/HGPRT mammalian cell mutation assay: Negative; in vitro cytogentics
- CHO cells (1 study; chromosome aberrations): Weakly positive; in
vitro UDS test using rat hepatocytes (3 studies; DNA damage and
repair): 2 negative; 1 equivocally positive, mouse micronucleus assay
(2 studies; chromosome aberrations): Negative, rat dominant lethal
assay: 1 study equivocally positive, 1 study negative. Overall
dimethenamid has been tested in 14 genetic toxicology assays. The
weight of the evidence demonstrates that dimethenamid is not genotoxic.
The following testing was performed with dimethenamid-P for
genotoxicity. A modified ames test (3 studies; point mutation):
Negative; in vitro CHO/HGPRT mammalian cell mutation assay (1 study;
point mutation): Negative; in vitro cytogentics - CHO cells (1 study;
chromosome aberrations): Negative; in vitro UDS test using rat
hepatocytes (1 study; DNA damage and repair): Negative; mouse
micronucleus assay (1 study; chromosome aberrations): Negative.
Dimethenamid-P has been tested in a total of 7 genetic toxicology
assays. These assays were performed both in vitro and in vivo and
multiple assays were conducted for each of the three EPA Guideline
requirement categories. Based on the data presented above, the data
indicates that dimethenamid-P does not induce gene mutations, is not
clastogenic and does not induce other effects indicative of
genotoxicity. Therefore, BASF concludes that dimethenamid-P does not
pose a mutagenic hazard to humans.
3. Reproductive and developmental toxicity--i. Rat. A developmental
rat study using dimethenamid via oral gavage resulted in dosages of 0,
50, 215, and 425 milligram per kilogram (mg/kg)/day with a development
toxicity no observed adverse effect level (NOAEL) of 215 mg/kg/day and
a maternal toxicity of 50 mg/kg/day based on the following: (1) Signs
of maternal toxicity, in the form of reduced body weight gain and food
consumption, increased liver weight and clinical observations were
observed at dose levels > 215 mg/kg/day with an increase in effects to
the upper dose level; (2) at the = 215 mg/kg/day dose levels slight
decreases in fetal body weights were observed which are not indicative
a teratogenic effect; and (3) at the 425 mg/kg/day dose level a slight
increase in resorptions was observed, and two fetuses had incomplete
ossified manubria. These effects are not indicative of a teratogenic
effect.
A developmental rat study using dimethenamid-P via oral gavage
resulted in dosages of 0, 25, 150, and 300 mg/kg/day with a development
toxicity NOAEL of 25 mg/kg/day and a maternal toxicity of 25 mg/kg/day
based on based on the following: (1) Signs of maternal toxicity, in the
form of decreased body weights and food consumption were observed at
dose levels > 150 mg/kg/day with an increase in effects to the upper
dose level; (2) at the 150 mg/kg/day dose level slight decreases in
fetal body weights and retarded ossification of the pelvis pubis were
observed which are not indicative a teratogenic effect; and (3) at the
300 mg/kg/day dose level slight decreases in fetal body weights,
microphthalmia in two fetuses/two litters, distended ureters, and
retarded ossification of the 2nd sternal centra and pelvis pubis were
observed, similarly, these effects are not indicative of a teratogenic
effect.
ii. Rabbits. A developmental study in rabbits using dimethenamid
via oral gavage resulted in dosages of 0, 37.5, 75, and 150 mg/kg/day
(HDT) with a development toxicity NOAEL of 75 mg/kg/day and a maternal
toxicity of 37.5 mg/kg/day based on: (1) Decreased body weight, food
consumption, and absorption/premature delivery in the 75 and 150 mg/kg/
day dose groups; and (2) effects on fetal development were a low
incidence of absorption/premature delivery and hyoid angulated changes
in the 150 mg/kg/day dose group which are not are indicative of a
teratogenic effect.
iii. Two-generation reproduction - rats. A two-generation
reproduction study using dimethenamid with rats fed dosages of 0, 7.5,
38, and 155 mg/kg/day (average mg/kg/day dose levels for both male and
female rats) with a reproductive NOAEL of 38 mg/kg/day and with a
parental NOAEL of 38 mg/kg/day based on: (1) Parental toxicity as
evident by reduction in body weight and food consumption and
significant increases in absolute and/or relative liver weights in both
males and female rats in the 155 mg/kg/day dose group; and (2)
significant reductions in pup weight during lactation were observed in
the 150 mg/kg/day dose group. No changes in pregnancy rates, fertility
or length of gestation were observed at all dose levels tested.
4. Chronic feeding and carcinogenicity. The established reference
dose (RfD) for dimethenamid and dimethenamid-P is based on a 2-year
feeding study in rats with dimethenamid, with a threshold NOAEL of 5.1
mg/kg/day. Using an uncertainty factor of 100, the RfD is calculated to
be 0.05 mg/kg/day. The following are summaries of the pertinent
toxicity data supporting dimethenamid tolerances:
i. Chronic feeding - nonrodent. A 1-year feeding study in dogs fed
dimethenamid at dosages of 0, 2, 9.6, or 49 mg/kg/day with a NOAEL of
9.6 mg/kg/day based on the following effects: (1) Slight decreases in
body weights for both the high dose male and female dogs as compared to
controls; (2) a variable degree of periportal hepatocyte vacuolation in
the high-dose male and female dogs; (3) minimal or mild hepatocyte
enlargement was similarly observed in the high-dose dogs; and (4) the
liver changes at the high-dose group correlated with increase in serum
alkaline phosphatase activity and cholesterol levels and increased
liver-to-body weight ratios in both male and female dogs.
ii. Chronic feeding/carcinogenicity - rat. A combined chronic
feeding/carcinogenicity study using dimethenamid was performed in rats
being fed dosages of 0, 5.1, 36, and 80 mg/kg/day (males) and 0, 6.8,
49, and 109 mg/kg/day (females) with a NOAEL of 5.1 mg/kg/day (males)
and 6.8 mg/kg/day (females) based on the following effects: (1)
Decreased body weights in both males and female rat at dose levels > 36
mg/kg/day dose groups with a slight progression of severity to the
upper level; (2) decreased food consumption in both males and female
rats at dose levels > 36 mg/kg/day dose groups with a slight
progression of severity to the upper dose level; (3) minimal
hematological and clinical chemistry value changes at dose levels > 36
mg/kg/day dose groups with very slight increase of severity at the
higher dose tested; (4) increased absolute liver weights for females at
dose levels > 49 mg/kg/day; (5) microscopic findings were observed in
the liver, parathyroid, and stomach of high-dose males, only, and
ovaries of high-dose females; and (6) an increased incidence of benign
and malignant tumors of the liver at the highest dose level tested. The
liver tumors observed in this study occurred at an incidence which was
slightly beyond the historical control range for this tumor type, and
occurred at the
[[Page 11854]]
maximum tolerated dose (MTD). Given the lack of structural activity
relationship (SAR) and the lack of mutagenicity discussed in section
B.2., it is BASFs opinion that dimethenamid-P should not be considered
a biologically relevant carcinogen in rats and the assessment is made
that the results of this carcinogenicity study do not indicate a
carcinogenic potential of the test substance for humans.
iii. Carcinogenicity - mice. A carcinogenicity study using
dimethenamid in mice fed dosages of 0, 3.8, 41, 205, and 431 (HDT) mg/
kg/day (males) and 0, 4.1, 41, 200, and 411 (HDT) mg/kg/day (females)
with a NOAEL of 41 mg/kg/day for male and female mice based on the
following effects: (1) Decreased body weights and food consumption were
observed in both males and female mice at the highest dose tested; (2)
increased liver weights were observed for male and female mice at the
highest dose tested at an interim sacrifice and increased weights for
kidney and liver were observed for female mice at dose levels > 200 mg/
kg/day at terminal sacrifice; (3) microscopic findings were observed in
the liver and stomach for both male and female mice at the upper dose
levels; (4) concerning the finding in the stomach, EPA has determined
that this finding was attributed to irritation of the material and the
finding was not toxicology significant; and (4) no increased incidence
of neoplasms occurred at any dose levels tested in this study. EPA has
concluded that this product is not carcinogenic under the conditions of
this study.
Dimethenamid is considered not to be carcinogenic in mice by BASF.
In the rat carcinogenicity study, a slight increase in liver tumors was
observed in males, only, at the highest dose tested. The liver tumors
observed in this study occurred at an incidence that was slightly
beyond the historical control range for this tumor type, and occurred
at the MTD. Dimethenamid shares no common mechanisms with other
compounds in the chloroacetanilide class of compounds. It is BASF's
opinion that dimethenamid and dimethenamid-P should not to be
considered biologically relevant carcinogens in rats and the assessment
is made that the results of this carcinogenicity study do not indicate
a carcinogenic potential of these substances for humans.
However, EPA has determined that dimethenamid is considered to be a
Group C carcinogen - possible human carcinogen - based on the judgment
of the EPA Carcinogenicity Peer Review Committee assessment. Also, the
Committee determined for risk assessment purposes, the RfD approach
should be used to quantify human risk. BASF agrees with the Agency that
the RfD approach for human risk assessment is valid.
5. Endocrine disruption. No specific tests have been performed with
dimethenamid-P or dimethenamid to determine whether the chemical may
have an effect in humans that is similar to an effect produced by
naturally occurring estrogen or other endocrine effects. However, there
are no significant findings in other relevant toxicity studies, i.e.
teratology and multi-generation reproductive studies, that would
suggest the dimethenamid produces endocrine related effects.
C. Aggregate Exposure
1. Dietary exposure--i. Food. BASF has reviewed the available
toxicology database to determine the endpoints of concern. For
dimethenamid and dimethenamid-P, BASF believes there is no concern
regarding an acute dietary risk since the available data do not
indicate any evidence of significant toxicity from a 1 day or single
event exposure by the oral route.
For the purpose of assessing the potential chronic dietary
exposure, BASF has estimated aggregate exposure based on theoretical
maximum residue contribution (TMRC) from the tolerance of dimethenamid
on sweet corn, sorghum, peanuts, and dry beans at 0.01 ppm for all uses
stated, respectively. The TMRC is a ``worse case'' estimate of dietary
exposure since it is assumed that 100% of all crops for which the
tolerances are established are treated and that pesticide residues are
always found at tolerance levels. EPA in a letter issued on October 13,
1995, for dimethenamid, determined the TMRC for the crops mentioned in
section C.1. to be 0.076 and 0.341 microgram (ug)/kg/day for the
general U.S. population and non-nursing infants (< 1), respectively.
Dimethenamid treated crops using the TMRC values utilized 0.15% and
0.683% for the general U.S. population and non-nursing infants (< 1),
respectively, of the RfD (0.05 mg/kg/day). These assessments are also
valid for dimethenamid-P. BASF concurs with this assessment.
The addition of an onion tolerance at 0.01 ppm has a TMRC of 0.0011
ug/kg/day for the general population and a TMRC of 0.0004 ug/kg/day for
non-nursing infants. Sugar beet tolerances at 0.01 ppm, add 0.0033 ug/
kg/day to the TMRC for the general population and 0.0013 ug/kg/day to
the TMRC for non-nursing infants. The addition of table beet tops, dry
bulb garlic, horseradish, and dry bulb shallot is negligible; table
beet root tolerances at 0.01 ppm add 0.00022 ug/kg/day to the TMRC for
the general population and 0.0019 ug/kg/day to the TMRC for non-nursing
infants. The addition of potato tolerances at 0.01 ppm would contribute
0.011 ug/kg/day to the TMRC for the general population and 0.014 ug/kg/
day to the TMRC for non-nursing infants. The addition of sweet potato
tolerances at 0.01 ppm would contribute 0.00039 ug/kg/day to the TMRC
for the general population and 0.0029 ug/kg/day to the TMRC for non-
nursing infants. The total RfD utilization from all uses, both
registered and proposed, is 0.18% for the general population, and 0.72%
for non-nursing infants.
Therefore, based on the completeness and reliability of the
toxicity data, and the exposure assessment discussed in section C.1.,
BASF concludes that there is a reasonable certainty that no harm will
result from aggregate exposure to residues of dimethenamid and
dimethenamid-P, including all anticipated dietary exposure.
ii. Drinking water. Other potential sources of exposure to
dimethenamid for the general population are residues in drinking water
and exposure from non-occupational sources. In a dimethenamid-P
environmental-fate risk assessment dated December 1998, EPA calculated
the following maximum concentrations for drinking water: Based on SCI-
GROW model calculations, ground-water concentrations were expected to
be < 1.0 parts per billion (ppb). Based on PRZM/EXAMS model
calculations for surface water, the maximum yearly average (chronic)
concentration was 5.4 ug/l from a Southeast corn scenario. Using these
values, the drinking water level of comparison (DWLOC) and the
aggregate RfD utilization are summarized in the table below.
------------------------------------------------------------------------
U.S. Non-nursing
population infants (%
(% of RfD) of RfD)
------------------------------------------------------------------------
Chronic dietary exposure 0.18 0.72
------------------------------------------------------------------------
Remainder RfD available for water (%) 99.82 99.32
(drinking water level of comparison)
------------------------------------------------------------------------
[[Page 11855]]
SCI-GROW ground water estimation\1\ < 0.10 0.20
------------------------------------------------------------------------
PRZM/EXAMS surface water estimation\1\ 0.30 1.10
------------------------------------------------------------------------
Total of RfD used by diet and water 0.58 2.00
------------------------------------------------------------------------
1Used highest values predicted from the model for all agricultural uses.
Assumes 2L/day and 70 kg adult; 1L/day and 10 kg infant.
2. Non-dietary exposure. For non-occupational exposure,
dimethenamid/ dimethenamid-P is not registered for either golf course
or homeowner uses which could contribute to ``non-dietary or other
exposure.''
D. Cumulative Effects
BASF has considered the potential for cumulative effects of
dimethenamid and other substances that have a common mechanism of
toxicity. BASF is aware of several other chloroacetanilide herbicides
that have been considered structurally similar to dimethenamid, these
being: Acetochlor, propachlor, butachlor, metolachlor, and alachlor.
However, BASF believes that consideration of a common mechanism of
toxicity to these products is not appropriate or valid. This conclusion
was based on the presentation EPA made to the EPA FIFRA Science
Advisory Panel (SAP) on March 20, 1997. The title of the presentation
was ``Grouping of Chloroacetanilide Pesticides Based on a Common
Mechanism of Toxicity.'' In this presentation EPA showed the structure
of several chloroacetanilides that included dimethenamid. BASF is
identifying Chlor-7 as dimethenamid. EPA concluded that Chlor-7 should
not be considered to have a common mechanism to the other
chloroacetanilides based on the following reasons:
[sbull] Except for Chlor-7 all other members of this case study
have a potential to generate a quinone imine. The quinone imine
intermediate, is capable of reacting with macromolecules.
[sbull] Chlor-7 has not produced nasal nor thyroid tumors in rats,
thus does not support inclusion in the group for a common mechanism for
these tumor types.
For liver tumors, Chlor-1, Chlor-7, Chlo-r5, and Chlor-6, can be
potentially grouped for a common mechanism, but EPA determined that
there is no knowledge of a common mechanism of toxicity or of a common
toxic species responsible for the effect. Therefore, EPA concluded that
because a mechanism can not be postulated, it believes that sufficient
evidence is not available to support a common mechanism for this tumor
type with these materials.
Therefore, BASF agrees with the position put forward by the Agency
and confirmed by the SAP that a common mechanism is inappropriate for
dimethenamid (Chlor-7) and the other chloroacetanilides mentioned in
section D. BASF has considered only the potential risks of dimethenamid
in its exposure assessment.
E. Safety Determination
1. U.S. population. Using the exposure assumptions described in
section C., based on the completeness and the reliability of the
toxicity data, BASF has estimated that aggregate exposure to
dimethenamid will utilize < 1% of the RfD (0.05 mg/kg/day) for the U.S.
population. EPA generally has no concern for exposure below 100% of the
RfD. Therefore, based on the completeness and reliability of the
toxicity data, and the exposure assessment discussed in sections B. and
C., BASF concludes that there is a reasonable certainty that no harm
will result from aggregate exposure to residues of dimethenamid
including all anticipated dietary exposure and all other non-
occupational exposures.
2. Infants and children. BASF cites results of developmental
toxicity studies reported in section B.3. including:
[sbull] Observed developmental toxicity effects in rats are not
indicative of teratogenic effect.
[sbull] The results of developmental study in rabbits also
demonstrated that dimethenamid is not a teratogenic compound and has a
development toxicity NOAEL of 75 mg/kg/day and a maternal toxicity of
37.5 mg/kg/day.
BASF believes that these test results demonstrate that the rat and
rabbit are similarly sensitive to dimethenamid. Additionally, the NOAEL
of 5 mg/kg/day from the chronic rat study used to set the RfD is 7.5X
and 5X lower than the maternal NOAELs established in the rabbit and rat
teratology studies, respectively. The developmental effects observed in
either the rat or rabbit occurred only at maternally toxic doses.
Therefore, BASF concludes that no additional safety factor is needed
for children.
F. International Tolerances
A maximum residue level has not been established under Codex
Alimentarius Commission for dimethenamid for any of the proposed uses.
[FR Doc. 03-5914 Filed 3-11-03; 8:45 am]
BILLING CODE 6560-50-S