dimethenamid (Frontier) Pesticide Tolerances 4/94
40 CFR Part 180
Pesticide Tolerances for Dimethenamid
AGENCY: Environmental Protection Agency (EPA).
ACTION: Final rule.
SUMMARY: This regulation establishes tolerances for residues
of the herbicide, dimethenamid, 2-chloro-N-[(1-methyl-2methoxy)ethyl]-
N-(2,4-dimethyl-thien-3-yl)-acetamide in or on the raw agricultural
commodity (RAC) soybeans at 0.01 parts per million (ppm). This
regulation to establish the maximum permissible level of residues
of the herbicide in or on this commodity was requested in a
petition submitted by Sandoz Agro Inc.
DATES: This regulation becomes effective on April 6, 1994.
ADDRESSES: Written objections and hearing requests, identified
by the document control number, [PP3F4177/R2052], may be submitted
to: Hearing Clerk (1900), Environmental Protection Agency, Rm.
M3708, 401 M St., SW., Washington, DC 20460. A copy of any objection
and hearing request filed with the Hearing Clerk should be identified
by the document control number and submitted to: Public Response
and Program Resources Branch, Field Operations Division (7505C),
Office of Pesticide Programs, Environmental Protection Agency,
401 M St., SW., Washington DC 20460. In Person, bring a copy
of objections and hearing requests to: Rm 1132, CM #2, 1921
Jefferson Davis Highway, Arlington, VA 22202.
Fees accompanying objections shall be labeled "Tolerance
Petition Fees" and forwarded to: EPA Headquarters Accounting
Operations Branch, OPP (Tolerance Fees), P.O. Box 360277M, Pittsburgh,
FOR FURTHER INFORMATION CONTACT: By mail: Cynthia Giles-Parker,
Product Manager (PM) 22, Registration Division, Environmental
Protection Agency, 401 M St., SW., Washington, DC 20460. Office
location and telephone number: Rm. 229, CM #2, 1921 Jefferson
Davis Highway, Arlington, VA 22202, (703-305-5540).
SUPPLEMENTARY INFORMATION: EPA issued a notice published in
the Federal Register on October 21, 1993 (58 FR 54353) which
announced that Sandoz Agro Inc., 1300 East Touhy Avenue, Des
Plaines, IL 60018, had submitted a pesticide petition (PP 3F4177)
to EPA requesting that the Administrator, pursuant to section
408(d) of the Federal Food, Drug, and Cosmetic Act (FFDCA),
21 U.S.C. 346a(d), establish tolerances for the residues of
the herbicide, dimethenamid, 2-chloro-N-[(1-methyl-2-methoxy)ethyl]-
N-(2,4-dimethyl-thien-3-yl)-acetamide in or on the RAC soybean
grain at 0.01 ppm. The Agency is editorially correcting the
RAC to read soybeans. There were no comments or requests for
referral to an advisory committee received in response to this
notice of filing. The data submitted in the petitions and all
other relevant material have been evaluated. The toxicology
data considered in support of the tolerances include:
1. A rat acute oral study with an LD50 of 2.14 grams (g)/kilogram
(kg), males, 1.30 g/kg females and 1.57 g/kg combined.
2. A 13-week rat feeding study with a no-observed effect
level (NOEL) of 500 ppm (33.5 milligrams (mg)/kg/day for males
and 40.1 mg/kg/day for females).
3. A 13-week dog feeding study with a NOEL of 100 ppm (2.5
4. A 21 day rabbit dermal study with a NOEL of 50 mg/kg/day
with mild irritant effect at all dose levels.
5. A carcinogenicity study in mice with no carcinogenic effects
observed at any dose level under the conditions of the study
and a systemic NOEL of 300 ppm (40.8 mg/kg/day for males and
40.1 mg/kg/day for females, based on food consumption) and a
systemic lowest effect level (LEL) of 1,500 ppm (205 mg/kg/day
for males and 200 mg/kg/day for females based on food consumption)
based on significantly elevated liver weights.
6. A rat chronic feeding/carcinogenicity study with a systemic
NOEL of 100 ppm (5 mg/kg/day) and a LEL of 700 ppm (35 mg/kg/day)
due to decreased food efficiency and histopathology findings.
Under the conditions of the study limited evidence of carcinogenicity
was observed based on a statistically significant increasing
trend for benign liver cell tumors in male rats and a statistically
significant increasing trend for ovarian tubular adenomas in
female rats. A re-evaluation of the ovarian neoplasia data indicated
that there was no statistically significant, dose-related, trend
in the incidence of ovarian tumors in female rats. This study
is discussed further below.
7. A 1 year dog feeding study with a NOEL of 250 ppm (9.6
mg/kg/day) and with a LEL = 1,250 ppm (49 mg/kg/day) based on
clinical chemistry and histological changes in liver.
8. A two generation reproduction study in rats with a parental
and reproductive NOEL of 500 ppm (36 mg/kg/day for males and
40 mg/kg/day for females) and a parental and reproductive LEL
of 2,000 ppm (150 mg/kg/day for males and 160 mg/kg/day for
females) based on reduction of body weight and of food consumption,
and increases in liver weights (parental toxicity), and significant
reductions in pup weight during lactation (reproductive toxicity).
9. A rabbit developmental study with a maternal NOEL of 37.5
mg/kg/day and a LEL of 75 mg/kg/day based on decreased body
weight and food consumption, and with a developmental NOEL of
75 mg/kg/day and a LEL of 150 mg/kg/day based on a low incidence
of abortion/premature delivery and angulation of the hyoid alae.
10. A rat developmental study with a maternal NOEL of 50
mg/kg/day and a LEL of 215 mg/kg/day based on excess salivation,
increased liver weight and reduced body weight gain and food
consumption, and with a developmental NOEL of 215 mg/kg/day
and a LEL of 425 mg/kg/day based on increased resorptions.
11. An Ames mutagenicity assay negative with and without
activation, an in vitro chromosomal aberration using CHO cells
positive with and without activation, an unscheduled DNA synthesis
in rat hepatocytes unequivocally positive in one in vitro assay
and negative in another in vitro assay. A Dominant Lethal Study
to further evaluate the mutagenic mechanism is due March 5,
1995 (2 years after the date of the initial conditional registration
of dimethenamid under the Federal Insecticide Fungicide and
Rodenticide Act [FIFRA]).
The Agency has concluded that the available data provide
limited evidence of carcinogenicity for dimethenamid in rats
and has classified the pesticide as a Category C carcinogen
(possible human carcinogen with limited evidence of carcinogenicity
in animals) in accordance with Agency guidelines, published
in the Federal Register in 1986 (51 FR 33992). Based on a review
by the Health Effects Division Peer Review Committee for Carcinogenicity
of the Office of Pesticide Programs, the Agency has determined
that a quantitative risk assessment is not appropriate for the
1. The tumor response was primarily due to a significantly
increasing trend for benign and/or malignant liver tumors in
males and due to a significantly increasing trend for ovarian
tubular adenomas in female rats. A re-evaluation of the ovarian
neoplasia data indicated that there was not a statistically
significant, dose-related, trend in the incidence of ovarian
tumors in female rats.
2. The chemical was not carcinogenic when administered in
the diet to mice at dose levels ranging from 30 to 3,000 ppm.
Based on this evidence, EPA concludes that dimethenamid poses
at most a negligible cancer risk to humans and that for purposes
of risk characterization the Reference Dose (RfD) approach should
be used for quantification of human risk. Residues of dimethenamid
will not concentrate in processed soybean commodities and a
food or feed additive regulation is not required for dimethenamid.
The standard risk assessment approach of using the RfD based
on systemic toxicity was applied to dimethenamid. Using a hundredfold
safety factor and the NOEL of 5 mg/kg bwt/day determined by
the most sensitive species from the 2-year rat feeding study,
the RfD is 0.05 mg/kg/day. The Anticipated Residue Contribution
(ARC) from the established tolerances is 0.000003 mg/kg bwt/day
and utilizes 0.007 percent of the RfD for the overall U. S.
population. The proposed use on soybeans would contribute an
additional 0.000068 mg/kg/day, raising the ARC to 0.000071 mg/kg
bwt/day, or 0.14 percent of the RfD. The exposure of the most
highly exposed subgroup in the population did not utilize a
significantly greater amount of the RfD.
Tolerances have been previously established for dimethenamid
in corn grain, corn fodder and corn forage. The metabolism of
dimethenamid in plants is adequately understood. There is no
reasonable expectation of secondary residues occurring in meat,
milk and eggs from the tolerance associated with this petition.
An adequate analytical method, gas chromatography, is available
for enforcement purposes. Because of the long lead time from
establishing these tolerances to publication of the enforcement
methodology in the Pesticide Analytical Manual, Vol. II, the
analytical methodology is being made available in the interim
to anyone interested in pesticide enforcement when requested
from: Calvin Furlow, Public Information Branch, Field Operations
Division (7506C), Office of Pesticide Programs, Environmental
Protection Agency, 401 M St., SW., Washington, DC 20460. Office
location and telephone number: Room 1130A, CM #2, 1921 Jefferson
Davis Highway, Arlington, VA 22202, (703-305-5937).
The pesticide is considered useful for the purposes for which
the tolerances are sought. Based on the information and data
considered, the Agency concludes that the establishment of the
tolerances will protect the public health. Therefore, the tolerances
are established as set forth below.
Any person adversely affected by this regulation may, within
30 days after publication of this document in the Federal Register,
file written objections and/or request a hearing with the Hearing
Clerk, at the address given above (40 CFR 178.20). A copy of
the objections and/or hearing requests filed with the Hearing
Clerk should be submitted to the OPP docket for this rulemaking.
The objections submitted must specify the provisions of the
regulation deemed objectionable and the grounds for the objections
(40 CFR 178.25). Each objection must be accompanied by the fees
provided by 40 CFR 180.33(i). If a hearing is requested, the
objections must include a statement of the factual issue(s)
on which a hearing is requested, and the requestor's contentions
on each such issue, and a summary of the evidence relied upon
by the objection (40 CFR 178.27). A request for a hearing will
be granted if the Administrator determines that the material
submitted shows the following: there is a genuine and substantial
issue of fact; there is a reasonable possibility that available
evidence identified by the requestor would, if established,
resolve one or more of such issues in favor of the requestor,
taking into account uncontested claims or facts to the contrary;
and resolution of the factual issue(s) in the manner sought
by the requestor would be adequate to justify the action requested
(40 CFR 178.32).
The Office of Management and Budget has exempted this rule
from the requirements of section 2 of Executive Order 12866.
Pursuant to the requirements of the Regulatory Flexibility
Act (Pub. L. 96-354, 94 Stat. 1164, 5 U.S.C. 601-612), the Administrator
has determined that regulations establishing new tolerances
or raising tolerance levels or establishing exemptions from
tolerance requirements do not have a significant economic impact
on a substantial number of small entities. A certification statement
to this effect was published in the Federal Register of May
4, 1981 (46 FR 24950).
List of Subjects in 40 CFR Part 180
Environmental protection, Administrative practice and procedure,
Agricultural commodities, Pesticides and pests, Reporting and
Dated: March 28, 1994.
Douglas D. Campt,
Director, Office of Pesticide Programs.
Therefore, chapter I of title 40 of the Code of Federal Regulations
is amended as follows:
PART 180 - [AMENDED]
1. The authority citation for Part 180 continues to read
Authority: 21 U.S.C. 346a and 371.
2. Section 180.464 is amended by revising the section heading
to read as set forth below and by alphabetically inserting in
the table the raw agricultural commodity, soybeans, to read
sec180.464 Dimethenamid, 2-chloro-N-[(1-methyl-2methoxy)ethyl]-
N-(2,4-dimethyl-thien-3-yl)-acetamide; tolerances for residues.
Commodities Parts per million
---------------------------------------------------------------- * * * * *
Soybeans ............................ 0.01
[FR Doc. 94-8104 Filed 4-5-94; 8:45 am]