Dimethenamid-p; Pesticide Tolerances for Emergency Exemptions

Note: EPA no longer updates this information, but it may be useful as a reference or resource.

[Federal Register: May 3, 2006 (Volume 71, Number 85)]
[Rules and Regulations]
[Page 25935-25942]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr03my06-10]

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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Part 180
[EPA-HQ-OPP-2006-0216; FRL-7770-8]

AGENCY: Environmental Protection Agency (EPA).
ACTION: Final rule.

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SUMMARY: This regulation establishes a time-limited tolerance for
residues of dimethenamid-p in or on squash, winter. This action is in
response to EPA's granting of an emergency exemption under section 18
of the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA)
authorizing use of the pesticide on squash, winter. This regulation
establishes a maximum permissible level for residues of squash, winter.
The tolerance will expire and is revoked on June 30, 2009.

DATES: This regulation is effective May 3, 2006. Objections and
requests for hearings must be received on or before July 3, 2006.

ADDRESSES: To submit a written objection or hearing request follow the
detailed instructions as provided in Unit VII. of the SUPPLEMENTARY
INFORMATION. EPA has established a docket for this action under Docket
identification (ID) number EPA-HQ-OPP-2006-0216. All documents in the docket
are listed on the http://www.regulations.gov web site. EDOCKET,
EPA's electronic public docket and comment system was replaced on November
25, 2005, by an enchanced Federal-wide electronic docket management and
comment system located at http://www.regulations.gov. Follow the
on-line instructions. 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 EDOCKET or in hard copy at the
Public Information and Records Integrity Branch (PIRIB), Rm. 119,
Crystal Mall #2, 1801 S. Bell St., 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.
? Important Note: OPP will be moving to a new location the
first week of May 2006. As a result, from Friday, April 28 to Friday,
May 5, 2006, the OPP Regulatory Public Docket will NOT be accepting any
deliveries at the Crystal Mall #2 address and this facility
will be closed to the public. Beginning on May 8, 2006, the OPP
Regulatory Public Docket will reopen at 8:30 a.m. and deliveries will
be accepted in Rm. S-4400, One Potomac Yard (South Building), 2777 S.
Crystal Drive, Arlington, VA 22202. The mail code for the mailing
address will change to (7502P), but will otherwise remain the same. The
OPP Regulatory Public Docket telephone number and hours of operation
will remain the same after the move.

FOR FURTHER INFORMATION CONTACT: Shaja R. Brothers, Registration
Division (7505C), Office of Pesticide Programs, Environmental
Protection Agency, 1200 Pennsylvania Ave., NW., Washington, DC 20460-
0001; telephone number: (703) 308-3194; e-mail address:
brothers.shaja@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:
? Crop production (NAICS code 111).
? Animal production (NAICS code 112).
? Food manufacturing (NAICS code 311).
? Pesticide manufacturing (NAICS code 32532).
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. 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 Access Electronic Copies of this Document and Other
Related Information?

In addition to using EDOCKET (http://www.regulations.gov/), you may
access this Federal Register document electronically through the EPA
Internet under the ``Federal Register'' listings at http://www.epa.gov/
fedrgstr/. A frequently updated electronic version of 40 CFR part 180
is available on E-CFR Beta Site Two at http://www.gpoaccess.gov/ecfr/.

II. Background and Statutory Findings

EPA, on its own initiative, in accordance with sections 408(e)
and408(l)(6) of the Federal Food, Drug, and Cosmetic Act (FFDCA), 21
U.S.C. 346a, is establishing a time-limited tolerance for residues of
the herbicide dimethenamid-p, 1-(RS)-2-chloro-N-[(1-methyl-2-
methoxy)ethyl]-N-(2,4-dimethylthien-3-yl)-acetamide in or on squash,
winter at 0.01 parts per million (ppm). Dimethenamid-p is a 90:10, S:R
mixture of dimethenamid isomers, and is already included in the
existing tolerances codified at 40 CFR 180.464. This tolerance will
expire and is revoked on June 30, 2009. EPA will publish a document in
the Federal Register to remove the revoked tolerance from the Code of
Federal Regulations.
Section 408(l)(6) of FFDCA requires EPA to establish a time-limited
tolerance or exemption from the requirement for a tolerance for
pesticide chemical residues in food that will result from the use of a
pesticide under an emergency exemption granted by EPA under section 18
of FIFRA. Such tolerances can be established without providing notice
or period for public comment. EPA does not intend for its actions on
section 18-related tolerances to set binding precedents for the
application of section 408 of FFDCA and the new safety standard to
other tolerances and exemptions. Section 408(e) of FFDCA allows EPA to
establish a tolerance or an exemption

[[Page 25936]]

from the requirement of a tolerance on its own initiative, i.e.,
without having received any petition from an outside party.
Section 408(b)(2)(A)(i) of FFDCA allows EPA to establish a
tolerance (the legal limit for a pesticide chemical residue in or on a
food) only if EPA determines that the tolerance is ``safe.'' Section
408(b)(2)(A)(ii) of FFDCA defines ``safe'' to mean that ``there is a
reasonable certainty that no harm will result from aggregate exposure
to the pesticide chemical residue, including all anticipated dietary
exposures and all other exposures for which there is reliable
information.'' This includes exposure through drinking water and in
residential settings, but does not include occupational exposure.
Section 408(b)(2)(C) of FFDCA requires EPA to give special
consideration to exposure of infants and children to the pesticide
chemical residue in establishing a tolerance and to ``ensure that there
is a reasonable certainty that no harm will result to infants and children
from aggregate exposure to the pesticide chemical residue. . . ..''
Section 18 of FIFRA authorizes EPA to exempt any Federal or State
agency from any provision of FIFRA, if EPA determines that ``emergency
conditions exist which require such exemption.'' This provision was not
amended by the Food Quality Protection Act of 1996 (FQPA). EPA has
established regulations governing such emergency exemptions in 40 CFR
part 166.

III. Emergency Exemption for Dimethenamid-p on Squash, Winter and FFDCA
Tolerances

Amiben (chlorambem) was the primary herbicide used in squash and
other cucurbits until 1991, when production of this herbicide ceased.
EPA did not revoke tolerances until 1999 to allow use of remaining
stocks. Growers began applying Amiben in banded strips over the crop
row, as the product was no longer available. By 2000, weed control had
become a major difficulty in squash.
Winter squash grown in western Oregon is processed for both puree
and seeds. Confectionary seed production constitutes 70% to 90% of the
market, depending on the year. Seed yield has been dropping
precipitously during the last 5 years (2000-2004). Fruit yield for
puree has not changed dramatically, but is far short of the production
goals expected before amiben was removed from the market. Growers
typically expected 25 to 30 tons per acre, and in some cases yields
were as high as 35 tons per acre during the 1980's. In contrast, fruit/
puree yield during the 5-year period of 2000-2004 averaged only about
18 tons per acre. The production cost have risen over the last 5 years,
while the price paid per product has remained nearly constant.
Consequently, growers had cut back their acreage of winter squash
during 2000-2004 to well below 4,500 acres, solely due to the lack of
weed control and resulting yield/economic losses.
EPA has authorized under FIFRA section 18 the use of dimethenamid-p
on squash, winter for control of nightshade and other summer weeds in
Oregon. After having reviewed the submission, EPA concurs that
emergency conditions exist for this State.
As part of its assessment of this emergency exemption, EPA assessed
the potential risks presented by residues of dimethenamid-p in or on
squash, winter. In doing so, EPA considered the safety standard in
section 408(b)(2) of FFDCA, and EPA decided that the necessary
tolerance under section 408(l)(6) of FFDCA would be consistent with the
safety standard and with FIFRA section 18. Consistent with the need to
move quickly on the emergency exemption in order to address an urgent
non-routine situation and to ensure that the resulting food is safe and
lawful, EPA is issuing this tolerance without notice and opportunity
for public comment as provided in section 408(l)(6) of FFDCA. Although
this tolerance will expire and is revoked on June 30, 2009, under
section 408(l)(5) of FFDCA, residues of the pesticide not in excess of
the amounts specified in the tolerance remaining in or on squash,
winter after that date will not be unlawful, provided the pesticide is
applied in a manner that was lawful under FIFRA, and the residues do
not exceed a level that was authorized by this tolerance at the time of
that application. EPA will take action to revoke this tolerance earlier
if any experience with, scientific data on, or other relevant
information on this pesticide indicates that the residues are not safe.
Because this tolerance is being approved under emergency
conditions, EPA has not made any decisions about whether dimethenamid-p
meets EPA's registration requirements for use on squash, winter or
whether a permanent tolerance for this use would be appropriate. Under
these circumstances, EPA does not believe that this tolerance serves as
a basis for registration of dimethenamid-p by a State for special local
needs under FIFRA section 24(c). Nor does this tolerance serve as the
basis for any State other than Oregon to use this pesticide on this
crop under section 18 of FIFRA without following all provisions of
EPA's regulations implementing FIFRA section 18 as identified in 40 CFR
part 166. For additional information regarding the emergency exemption
for dimethenamid-p, contact the Agency's Registration Division at the
address provided under FOR FURTHER INFORMATION CONTACT.

IV. Aggregate Risk Assessment and Determination of Safety

EPA performs a number of analyses to determine the risks from
aggregate exposure to pesticide residues. For further discussion of the
regulatory requirements of section 408 of FFDCA and a complete
description of the risk assessment process, see the final rule on
Bifenthrin Pesticide Tolerances (62 FR 62961, November 26, 1997) (FRL-
5754-7).
Consistent with section 408(b)(2)(D) of FFDCA, EPA has reviewed the
available scientific data and other relevant information in support of
this action. EPA has sufficient data to assess the hazards of
dimethenamid-p and to make a determination on aggregate exposure,
consistent with section 408(b)(2) of FFDCA, for a time-limited
tolerance for residues of dimethenamid-p in or on squash, winter at
0.01 ppm. EPA's assessment of the dietary exposures and risks
associated with establishing the tolerance follows.

A. Toxicological Endpoints

The dose at which no adverse effects are observed (the NOAEL) from
the toxicology study identified as appropriate for use in risk
assessment is used to estimate the toxicological endpoint. However, the
lowest dose at which adverse effects of concern are identified (the
LOAEL) is sometimes used for risk assessment if no NOAEL was achieved
in the toxicology study selected. An uncertainty factor (UF) is applied
to reflect uncertainties inherent in the extrapolation from laboratory
animal data to humans and in the variations in sensitivity among
members of the human population as well as other unknowns. An UF of 100
is routinely used, 10X to account for inter-species differences and 10X
for intra-species differences. A 3X UF was added for short-term dermal
and inhalation exposure for S-dimethenamid-p due to the absence of a
maternal NOAEL, and a lower LOAEL in comparison to S-dimethenamid-RS
shown in the developmental toxicity study in rats.
For dietary risk assessment (other than cancer) the Agency uses the
UF to calculate an acute or chronic reference dose (aRfD or cRfD) where
the RfD is

[[Page 25937]]

equal to the NOAEL divided by the appropriate UF (RfD = NOAEL/UF).
Where an additional safety factor is retained due to concerns unique to
FQPA, this additional factor is applied to the RfD by dividing the RfD
by such additional factor. The acute or chronic Population Adjusted
Dose (aPAD or cPAD) is a modification of the RfD to accommodate this
type of FQPA SF.
For non-dietary risk assessments (other than cancer) the UF is used
to determine the level of concern (LOC). For example, when 100 is the
appropriate UF (10X to account for interspecies differences and 10X for
intraspecies differences) the LOC is 100. To estimate risk, a ratio of
the NOAEL to exposures (margin of exposure (MOE) = NOAEL/exposure) is
calculated and compared to the LOC.
The linear default risk methodology (Q*) is the primary method
currently used by the Agency to quantify carcinogenic risk. The Q*
approach assumes that any amount of exposure will lead to some degree
of cancer risk. A Q* is calculated and used to estimate risk which
represents a probability of occurrence of additional cancer cases
(e.g., risk is expressed as 1 x 10-6 or one in a million).
Under certain specific circumstances, MOE calculations will be used for
the carcinogenic risk assessment. In this non-linear approach, a
``point of departure'' is identified below which carcinogenic effects
are not expected. The point of departure is typically a NOAEL based on
an endpoint related to cancer effects though it may be a different
value derived from the dose response curve. To estimate risk, a ratio
of the point of departure to exposure margin of exposure (MOE)
_cancer = point of departure/exposures) is calculated.
Much of the existing toxicological and residue chemistry data base
for dimethenamid is based on studies conducted with the racemic (50:50)
mixture of S and R isomers. EPA has previously concluded that the data
base is adequate for the risk assessment of both the racemic
dimethenamid and the 90:10, S:R dimethenamid-p in the Federal Register
of September 24, 2004 (69 FR 57197) (FRL-7680-1). A summary of the
toxicological endpoints for dimethenamid-p used for human risk
assessment is shown in the following Table 1:

Table 1.--Summary of Toxicological Dose and Endpoints for Dimethenamid-p for Use in Human Risk Assessment
----------------------------------------------------------------------------------------------------------------
Dose Used in Risk
Assessment, Special FQPA SF and
Exposure/Scenario* Interspecies, Level of Concern for Study and Toxicological
Intraspecies, and any Risk Assessment Effects
Traditional UF
----------------------------------------------------------------------------------------------------------------
Acute dietary (females 13-49 years of NOAEL = 75 milligram/ FQPA SF = 1X Developmental toxicity
age) based on RS data kilogram/day (mg/kg/ aPAD = acute RfD / FQPA in rabbits
day) SF = 0.75 mg/kg/day. Maternal LOAEL = 150 mg/
UF = 100............... kg/day based on
Acute RfD = 0.75 mg/kg/ abortions and
day. decreased body weight
gain and food
consumption
Developmental LOAEL =
150 mg/kg/day based on
post-implantation loss
----------------------------------------------------------------------------------------------------------------
Acute dietary (general population Not applicable. No studies identify an acute hazard (dose and endpoint)
including infants and children) based on a single-oral exposure (dose)
----------------------------------------------------------------------------------------------------------------
Chronic dietary (all populations) NOAEL= 5 mg/kg/day FQPA SF = 1X Chronic/carcinogenicity
based on RS data UF = 100............... cPAD = chronic RfD / rats
Chronic RfD = 0.05 mg/ FQPA SF = 0.05 mg/kg/ LOAEL = Male/Female (M/
kg/day. day. F); 36/49 mg/kg/day
based on decreased
body weight and body
weight gain in both
sexes, increased food
conversion ratios in
females, and increased
microscopic hepatic
lesions in both sexes
----------------------------------------------------------------------------------------------------------------
Dermal absorption based on RS data 30% No studies are available. Value estimated from
the ratio of the LOAEL for maternal weight
decrement in developmental study to LOAEL for
male weight decrement in the 21-day dermal
study.Ratio of (developmental rabbit maternal
LOAEL, body weight) / (21-day dermal rabbit
LOAEL for systemic toxicity, body weight) x 100
= (150/500) x 100 = 30%
----------------------------------------------------------------------------------------------------------------
Dermal short-term (1-30 days) NOAEL = 25/3(UF) = 8 mg/ Developmental toxicity study in rats (MRID
kg/day 44332243). LOAEL = 25 mg/kg/day was based on
Dermal absorption = 30% maternal body weight decrement, body weight
UF = 32; MOE = 3005.... gain decrement and decreased food consumption.
----------------------------------------------------------------------------------------------------------------
Dermal Intermediate-term, (1-6 NOAEL = 6.8 mg/kg/day Chronic feeding study in rats (MRID 41706808 and
months) (F) 42030102). LOAEL = 36/49 mg/kg/day (M/F) based
Dermal absorption = 30% on decreased body weight and body weight gain
UF = 1................. and at termination increased microscopic
MOE = 100.............. hepatic lesions. NOAEL = 5.1/6.8 mg/kg/day for
(M/F)
----------------------------------------------------------------------------------------------------------------
Inhalation, short-term (1-30 days) NOAEL = 8 mg/kg/day (F) Same as dermal, short-term
Inhalation absorption =
100%.
UF = 32................
MOE = 300..............
----------------------------------------------------------------------------------------------------------------
----------------------------------------------------------------------------------------------------------------

[[Page 25938]]

Table 1.--Summary of Toxicological Dose and Endpoints for Dimethenamid-p for Use in Human Risk Assessment--
Continued
----------------------------------------------------------------------------------------------------------------
Dose Used in Risk
Assessment, Special FQPA SF and
Exposure/Scenario* Interspecies, Level of Concern for Study and Toxicological
Intraspecies, and any Risk Assessment Effects
Traditional UF
----------------------------------------------------------------------------------------------------------------
Inhalation intermediate-term (1-6 NOAEL = 6.8 mg/kg/day Same as dermal intermediate-term
months) (F)
Inhalation absorption =
100%.
UF = 1.................
MOE = 100..............
----------------------------------------------------------------------------------------------------------------
Cancer Classified as ``C'' a possible human carcinogen; however, no Q1* was has
been established for an assessment of cancer risk.
----------------------------------------------------------------------------------------------------------------
* The reference to the FQPA SF refers to any additional SF retained due to concerns unique to FQPA.

B. Exposure Assessment

1. Dietary exposure from food and feed uses. Tolerances have been
established (40 CFR 180.464(a)) for the residues of dimethenamid-p, in
or on bean, dry, seed; beet, garden, roots; beet, garden, tops; beet,
sugar, dried pulp; beet, sugar, molasses; beet, sugar, roots; beet,
sugar, tops; corn, field, forage; corn, field, grain; corn, field,
stover; corn, pop, forage; corn, pop, grain; corn, pop, stover; corn,
sweet, forage; corn, sweet, kernal plus cob with husk removed; corn,
sweet, stover; garlic; horseradish; onion, dry bulb; peanut, hay;
peanut, nutmeat; shallot, bulb; sorghum, grain; sorghum, grain, forage;
sorghum, grain, stover; soybean, seed; and tuberous and corm
vegetables. The tolerance expression includes both the R and S isomers,
these tolerances also cover the registered uses of dimethenamid-p. The
current tolerances for all plant commodities are set at 0.01 ppm. Risk
assessments were conducted by EPA to assess dietary exposures from
dimethenamid-p in food as follows:
i. Acute exposure. Acute dietary risk assessments are performed for
a food-use pesticide if a toxicological study has indicated the
possibility of an effect of concern occurring as a result of a 1 day or
single exposure. The Dietary Exposure Evaluation Model (DEEM\TM\)
analysis evaluated the individual food consumption as reported by
respondents in the U.S. Department of Agriculture (USDA) 1994-1996, and
1998 nationwide Continuing Surveys of Food Intake by Individuals
(CSFII) and accumulated exposure to the chemical for each commodity.
The following assumptions were made for the acute exposure assessments:
The acute dietary analysis is conservative, based on tolerance-level
residues and 100% crop treated assumptions for all commodities.
ii. Chronic exposure. In conducting this chronic dietary risk
assessment the DEEM\TM\ analysis evaluated the individual food
consumption as reported by respondents in the USDA 1994, 1996, and 1998
nationwide CSFII and accumulated exposure to the chemical for each
commodity. The following assumptions were made for the chronic exposure
assessments: The chronic dietary analysis is conservative, based on
tolerance-level residues and 100% crop treated assumptions for all
commodities.
iii. Cancer. Dimethenamid-p has been classified as a Category ``C''
(possible human carcinogen). Based on increased tumor incidence only in
rats (not mice). The Agency determined that a quantitative cancer risk
assessment is not required. The RfD approach was used to estimate
cancer risk. Therefore, the chronic (non-cancer) risk assessment is an
adequate estimate of cancer risk as well as other chronic effects.
2. Dietary exposure from drinking water. The Agency lacks
sufficient monitoring exposure data to complete a comprehensive dietary
exposure analysis and risk assessment for dimethenamid-p in drinking
water. Because the Agency does not have comprehensive monitoring data,
drinking water concentration estimates are made by reliance on
simulation or modeling taking into account data on the physical
characteristics of dimethenamid-p.
The Agency uses the Generic Estimated Environmental Concentration
(GENEEC) or the Pesticide Root Zone/Exposure Analysis Modeling System
(PRZM/EXAMS) to estimate pesticide concentrations in surface water and
Screening Concentration in Groundwater (SCI-GROW), which predicts
pesticide concentrations in ground water. In general, EPA will use
GENEEC (a Tier I model) before using PRZM/EXAMS (a Tier II model) for a
screening-level assessment for surface water. The GENEEC model is a
subset of the PRZM/EXAMS model that uses a specific high-end runoff
scenario for pesticides. GENEEC incorporates a farm pond scenario,
while PRZM/EXAMS incorporate an index reservoir environment in place of
the previous pond scenario. The PRZM/EXAMS model includes a percent
crop (PC) area factor as an adjustment to account for the maximum PC
coverage within a watershed or drainage basin.
None of these models include consideration of the impact processing
(mixing, dilution, or treatment) of raw water for distribution as
drinking water would likely have on the removal of pesticides from the
source water. The primary use of these models by the Agency at this
stage is to provide a coarse screen for sorting out pesticides for
which it is highly unlikely that drinking water concentrations would
ever exceed human health levels of concern.
Based on the PRZM/EXAMS and SCI-GROW models, the estimated
environmental concentrations (EECs) of dimethenamid-p for acute
exposures are estimated to be 49 parts per billion (ppb) for surface
water and 0.42 ppb for ground water. The EECs for chronic exposures are
estimated to be 7.9 ppb for surface water and 0.42 ppb for ground water.
3. From non-dietary exposure. The term ``residential exposure'' is
used in this document to refer to non-occupational, non-dietary
exposure (e.g., for lawn and garden pest control, indoor pest control,
termiticides, and flea and tick control on pets). Dimethenamid-p is not
registered for use on any sites that would result in residential exposure.
4. Cumulative effects from substances with a common mechanism of
toxicity. Section 408(b)(2)(D)(v) of FFDCA requires that, when
considering whether to establish, modify, or revoke a tolerance, the
Agency consider ``available information'' concerning the cumulative
effects of a particular pesticide's residues and ``other substances
that have a common mechanism of toxicity.''
Unlike other pesticides for which EPA has followed a cumulative
risk approach

[[Page 25939]]

based on a common mechanism of toxicity, EPA has not made a common
mechanism of toxicity finding as to dimethenamid-p and any other
substances and dimethenamid-p does not appear to produce a toxic
metabolite produced by other substances. For the purposes of this
tolerance action, therefore, EPA has not assumed that dimethenamid-p
has a common mechanism of toxicity with other substances. For
information regarding EPA's efforts to determine which chemicals have a
common mechanism of toxicity and to evaluate the cumulative effects of
such chemicals, see the policy statements released by EPA's Office of
Pesticide Programs concerning common mechanism determinations and
procedures for cumulating effects from substances found to have a
common mechanism on EPA's Web site at
http://www.epa.gov/pesticides/cumulative/.

C. Safety Factor for Infants and Children

1. In general. Section 408 of FFDCA provides that EPA shall apply
an additional tenfold margin of safety for infants and children in the
case of threshold effects to account for prenatal and postnatal
toxicity and the completeness of the data base on toxicity and exposure
unless EPA determines that a different margin of safety will be safe
for infants and children. Margins of safety are incorporated into EPA
risk assessments either directly through use of a MOE analysis or
through using uncertainty (safety) factors in calculating a dose level
that poses no appreciable risk to humans.
2. Developmental toxicity studies. In a developmental toxicity
study in rats, maternal toxicity was evidenced by excessive salivation,
increased liver weight and reduced body weight gain and food
consumption at 215 and 425 milligrams per kilogram per day (mg/kg/day).
Developmental toxicity was evidenced by an increased incidence of
resorption in the 425 mg/kg/day rats. The maternal NOAEL is 50 mg/kg/
day and the maternal LOAEL is 215 mg/kg/day. The developmental NOAEL is
215 mg/kg/day and the developmental LOAEL is 425 mg/kg/day.
In a developmental toxicity study in rabbits, maternal toxicity was
evidenced by decreased body weight, food consumption and increased
abortion/premature delivery at 75 and 150 mg/kg/day. Developmental
toxicity was evidenced by increased abortion/premature delivery and
hyoid alae angulated changes in the 150 mg/kg group. The maternal NOAEL
is 37.5 mg/kg/day and the maternal LOAEL is 75 mg/kg/day. The
developmental NOAEL is 75 mg/kg/day and the developmental LOAEL is 150
mg/kg/day.
3. Reproductive toxicity study. In a 2-generation reproductive
study in rats, parental toxicity was evidenced by significant
reductions in body weight and food consumption in males and significant
increases in absolute and relative liver weights in both sexes.
Significant reductions in pup weight during lactation occurred at 150
mg/kg/day. The parental NOAEL is 36 mg/kg/day and the parental LOAEL is
150 mg/kg/day. The reproduction NOAEL is 36 mg/kg/day and the
reproduction LOAEL is 150 mg/kg/day.
4. Prenatal and postnatal sensitivity. No offspring prenatal or
postnatal susceptibility to either RS-dimethenamid or S-dimethenamid-p
was seen in a rabbit or two rat developmental studies and reproduction
study. There is low concern for prenatal or postnatal toxicity since
the developmental effects from the S and RS mixture are similar and
occur at similar doses.
5. Conclusion. There is a complete toxicity data base for
dimethenamid-p and exposure data are complete or are estimated based on
data that reasonably accounts for potential exposures. EPA determined
the 10X safety factor to protect infants and children should be reduced
to 1X because there are low concerns, and no residual uncertainties
with regard to prenatal and/or postnatal toxicity. Additionally,
developmental, reproductive, and prenatal-postnatal effects were seen
only at levels above those that caused effects in adults.

D. Aggregate Risks and Determination of Safety

Aggregate dietary risk for dimethenamid-p is assessed by comparing
acute and chronic dietary (food and drinking water) exposure estimates
to their respective aPAD and cPAD, with risk expressed as a percent of
the PAD. Acute and chronic water residues were incorporated into the
dietary exposure analyses. There are no residential uses of
dimethenamid-p. Therefore, the reported acute and chronic dietary
exposures are aggregate food and water risks associated with the
proposed section 18 use (squash, winter), and the existing registered uses.
The acute and chronic aggregate (food and drinking water) exposure
assessment was conducted using the DEEM software with the Food
Commodity Intake Database (DEEM\TM\/FCID), Version 1.3) which
incorporates consumption data from the USDA CSFII, 1994-1996 and 1998.
The 1994-1996 and 1998 data are based on the reported consumption of
more than 20,000 individuals over 2 non-consecutive survey days.
Consumption data are averaged for the entire U.S. population and within
population subgroups for chronic exposure assessment, but are retained
as individual consumption ``events'' for acute exposure assessment.
Exposure estimates are expressed in mg/kg body weight/day and risk as a
percent of the aPAD/cPAD.
An upper-bound (Tier 1) acute and chronic aggregate risk assessment
was conducted for dimethenamid-p food commodities and drinking water
combined. The residue estimate for each food commodity is based on the
tolerance for that crop (0.01 ppm) and each crop is assessed as if 100%
of the crop has been treated with dimethenamid-p. The EEC inputs
(acute/chronic) for drinking water are described as ``Tier 2,'' but are
considered upper-bound estimates for finished drinking water. It should
also be noted that, like the tolerance level inputs for foods, the
residue inputs for drinking water are point estimates rather than a
residue distribution (as seen in probabilistic assessments).
1. Acute risk. Using the exposure assumptions discussed in this
unit for acute exposure, the acute dietary exposure to dimethenamid-p
from food will occupy 0.32% of the aPAD for females 13-49 years and
older. EPA does not expect the aggregate exposure to exceed 100% of the
aPAD, as shown in the following Table 2:

[[Page 25940]]

Table 2.--Aggregate Risk Assessment for Chronic (Non-Cancer) Exposure to Dimethenamid-p
----------------------------------------------------------------------------------------------------------------
DEEM\TM\-FCID
Population Subgroup PAD, mg/kg/day -------------------------------------------------
Exposure, mg/kg/day %PAD
----------------------------------------------------------------------------------------------------------------
Acute dietary estimates (95th percentile of exposure)
----------------------------------------------------------------------------------------------------------------
Females 13-49 years 0.75 0.002416 < 1
----------------------------------------------------------------------------------------------------------------

2. Chronic risk. Using the exposure assumptions described in this
unit for chronic exposure, EPA has concluded that exposure to
dimethenamid-p from food will utilize 0.4% of the cPAD for the U.S.
population, 1.2% of the cPAD for all infants < 1 year old and0.7% of the
cPAD for children 1-2 years old. There are no residential uses for
dimethenamid-p that result in chronic residential exposure to
dimethenamid-p. EPA does not expect the aggregate exposure to exceed
100% of the cPAD, as shown in the following Table 3:

Table 3.--Aggregate Risk Assessment for Chronic (Non-Cancer) Exposure to Dimethenamid-p
----------------------------------------------------------------------------------------------------------------
DEEM\TM\-FCID
Population Subgroups PAD, mg/kg/day -------------------------------------------------
Exposure, mg/kg/day %PAD
----------------------------------------------------------------------------------------------------------------
Chronic PAD Dietary Estimates
----------------------------------------------------------------------------------------------------------------
U.S. Population...................... 0.05 0.000205 < 1
----------------------------------------------------------------------------------------------------------------
All infants (< 1 year) 0.05 0.000605 1.2
----------------------------------------------------------------------------------------------------------------
Children (1-2 years) 0.05 0.000329 < 1
----------------------------------------------------------------------------------------------------------------
Children (3-5 years) 0.05 0.000315 < 1
----------------------------------------------------------------------------------------------------------------
Children (6-12 years) 0.05 0.000221 < 1
----------------------------------------------------------------------------------------------------------------
Youth (13-19 years) 0.05 0.000163 < 1
----------------------------------------------------------------------------------------------------------------
Adults (20-49 years) 0.05 0.000187 < 1
----------------------------------------------------------------------------------------------------------------
Adults (50+ years) 0.05 0.000189 < 1
----------------------------------------------------------------------------------------------------------------

3. Short-term risk. Short-term aggregate exposure takes into
account residential exposure plus chronic exposure to food and water
(considered to be a background exposure level).
Dimethenamid-p is not registered for use on any sites that would
result in residential exposure. Therefore, the aggregate risk is the
sum of the risk from food and water, which were previously addressed.
4. Intermediate-term risk. Intermediate-term aggregate exposure
takes into account non-dietary, non-occupational exposure plus chronic
exposure to food and water (considered to be a background exposure
level). Dimethenamid-p is not registered for use on any sites that
would result in residential exposure. Therefore, the aggregate risk is
the sum of the risk from food and water, which were previously addressed.
5. Aggregate cancer risk for U.S. population. Dimethenamid-p has
been classified as a Category ``C'' (possible human carcinogen). Based
on increased tumor incidence only in rats (not mice), the Agency
determined that a quantitative cancer risk assessment is not required.
The RfD approach was used to estimate cancer risk. Therefore the
chronic (non-cancer) risk assessment is an adequate estimate of cancer
risk as well as other chronic effects.
6. Determination of safety. Based on these risk assessments, EPA
concludes that there is a reasonable certainty that no harm will result
to the general population, and to infants and children from aggregate
exposure to dimethenamid-p residues.

V. Other Considerations

A. Analytical Enforcement Methodology

An adequate enforcement method is available for determining
dimethenamid residues in plants and soil. The Gas Chromatography/
Nitrogen Phosphorus Detection (GC/NPD) method (AM-0884-0193-1) has been
validated by the Agency and submitted for publication in FDA's
Pesticide Analytical Manual, Volume II. The method does not separate
the R and S isomers of dimethenamid and the limit of quantitation (LOQ)
is 0.01 ppm. Thus, adequate enforcement methodology is available to
enforce the tolerance expression. The method may be requested from:
Chief, Analytical Chemistry Branch, Environmental Science Center, 701
Mapes Rd., Ft. Meade, MD 20755-5350; telephone number: (410) 305-2905;
e-mail address: residuemethods@epa.gov.

B. International Residue Limits

There are no CODEX or Canadian maximum residue limits established
for dimethenamid or dimethenamid-p. Therefore, tolerance harmonization
is not germane to the current section 18 proposed use.

VI. Conclusion

Therefore, the time-limited tolerance is established for residues
of dimethenamid-p, 1-RS-2-chloro-N-[(1-methyl-2-methoxy)ethyl]-N-(2,4-
dimethylthien-3-yl)-acetamide in or on squash, winter at 0.01 ppm.

VII. Objections and Hearing Requests

Under section 408(g) of FFDCA, as amended by FQPA, any person may
file an objection to any aspect of this regulation and may also request
a hearing on those objections. The EPA

[[Page 25941]]

procedural regulations which govern the submission of objections and
requests for hearings appear in 40 CFR part 178. Although the
procedures in those regulations require some modification to reflect
the amendments made to FFDCA by FQPA, EPA will continue to use those
procedures, with appropriate adjustments, until the necessary
modifications can be made. The new section 408(g) of FFDCA provides
essentially the same process for persons to ``object'' to a regulation
for an exemption from the requirement of a tolerance issued by EPA
under new section 408(d) of FFDCA, as was provided in the old sections
408 and 409 of FFDCA. However, the period for filing objections is now
60 days, rather than 30 days.

A. What Do I Need to Do to File an Objection or Request a Hearing?

You must file your objection or request a hearing on this
regulation in accordance with the instructions provided in this unit
and in 40 CFR part 178. To ensure proper receipt by EPA, you must
identify docket ID number EPA-HQ-OPP-2006-0216 in the subject line on
the first page of your submission. All requests must be in writing, and
must be mailed or delivered to the Hearing Clerk on or before July 3, 2006.
1. Filing the request. Your objection must specify the specific
provisions in the regulation that you object to, and the grounds for
the objections (40 CFR 178.25). If a hearing is requested, the
objections must include a statement of the factual issue(s) on which a
hearing is requested, the requestor's contentions on such issues, and a
summary of any evidence relied upon by the objector (40 CFR 178.27).
Information submitted in connection with an objection or hearing
request may be claimed confidential by marking any part or all of that
information as CBI. Information so marked will not be disclosed except
in accordance with procedures set forth in 40 CFR part 2. A copy of the
information that does not contain CBI must be submitted for inclusion
in the public record. Information not marked confidential may be
disclosed publicly by EPA without prior notice.
Mail your written request to: Office of the Hearing Clerk (1900L),
Environmental Protection Agency, 1200 Pennsylvania Ave., NW.,
Washington, DC 20460-0001. You may also deliver your request to the
Office of the Hearing Clerk in Suite 350, 1099 14\th\ St., NW.,
Washington, DC 20005. The Office of the Hearing Clerk is open from 8
a.m. to 4 p.m., Monday through Friday, excluding legal holidays. The
telephone number for the Office of the Hearing Clerk is (202) 564-6255.
2. Copies for the Docket. In addition to filing an objection or
hearing request with the Hearing Clerk as described in Unit VII.A1.,
you should also send a copy of your request to the PIRIB for its
inclusion in the official record that is described in ADDRESSES. Mail
your copies, identified by the docket ID number EPA-HQ-OPP-2006-0216,
to: Public Information and Records Integrity Branch, Information
Technology and Resources Management Division (7502C), Office of
Pesticide Programs, Environmental Protection Agency, 1200 Pennsylvania
Ave., NW., Washington, DC 20460-0001. In person or by courier, bring a
copy to the location of the PIRIB described in ADDRESSES.

B. When Will the Agency Grant a Request for a Hearing?

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).

VIII. Statutory and Executive Order Reviews

This final rule establishes a time-limited tolerance under section
408 of FFDCA. The Office of Management and Budget (OMB) has exempted
these types of actions from review under Executive Order 12866,
entitled Regulatory Planning and Review (58 FR 51735, October 4, 1993).
Because this rule has been exempted from review under Executive Order
12866 due to its lack of significance, this rule is not subject to
Executive Order 13211, Actions Concerning Regulations That
Significantly Affect Energy Supply, Distribution, or Use (66 FR 28355,
May 22, 2001). This final rule does not contain any information
collections subject to OMB approval under the Paperwork Reduction Act
(PRA), 44 U.S.C. 3501 et seq., or impose any enforceable duty or
contain any unfunded mandate as described under Title II of the
Unfunded Mandates Reform Act of 1995 (UMRA) (Public Law 104-4). Nor
does it require any special considerations under Executive Order 12898,
entitled Federal Actions to Address Environmental Justice in Minority
Populations and Low-Income Populations (59 FR 7629, February 16, 1994);
or OMB review or any Agency action under Executive Order 13045,
entitled Protection of Children from Environmental Health Risks and
Safety Risks (62 FR 19885, April 23, 1997). This action does not
involve any technical standards that would require Agency consideration
of voluntary consensus standards pursuant to 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). Since
tolerances and exemptions that are established on the basis of a FIFRA
section 18 exemption under section 408 of FFDCA, such as the tolerance
in this final rule, do not require the issuance of a proposed rule, the
requirements of the Regulatory Flexibility Act (RFA) (5 U.S.C. 601 et
seq.) do not apply. In addition, the Agency has determined that this
action will not have a substantial direct effect on 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, entitled Federalism
(64 FR 43255, August 10, 1999). Executive Order 13132 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 final rule directly regulates growers, food
processors, food handlers, and food retailers, not States. This action
does not alter the relationships or distribution of power and
responsibilities established by Congress in the preemption provisions
of section 408(n)(4) of FFDCA. For these same reasons, the Agency has
determined that this rule does not have any ``tribal implications'' as
described in Executive Order 13175, entitled Consultation and
Coordination with Indian Tribal Governments (59 FR 22951, November 6,
2000). Executive Order 13175, 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

[[Page 25942]]

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 rule 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 Federal
Government and Indian tribes, as specified in Executive Order 13175.
Thus, Executive Order 13175 does not apply to this rule.

IX. Congressional Review Act

The Congressional Review Act, 5 U.S.C. 801 et seq., as added by the
Small Business Regulatory Enforcement Fairness Act of 1996, generally
provides that before a rule may take effect, the agency promulgating
the rule must submit a rule report, which includes a copy of the rule,
to each House of the Congress and to the Comptroller General of the
United States. EPA will submit a report containing this rule and other
required information to the U.S. Senate, the U.S. House of
Representatives, and the Comptroller General of the United States prior
to publication of this final rule in theFederal Register. This final
rule is not a ``major rule'' as defined by 5 U.S.C. 804(2).

List of Subjects in 40 CFR Part 180

Environmental protection, Administrative practice and procedure,
Agricultural commodities, Pesticides and pests, Reporting and
recordkeeping requirements.

Dated: April 25, 2006.
Lois Rossi,
Director, Registration Division, Office of Pesticide Programs.

? Therefore, 40 CFR chapter I is amended as follows:

PART 180--[AMENDED]

? 1. The authority citation for part 180 continues to read as follows:

Authority: 21 U.S.C. 321(q), 346a and 371.

? 2. Section 180.464 is amended by adding text to paragraph (b) after the
paragraph heading to read as follows:

Sec. 180.464 Dimethenamid; tolerances for residues.

* * * * *
(b) * * * A time-limited tolerance is established for residues of
dimethenamid-p, 1-(RS)-2-chloro-N-[(1-methyl-2-methoxy)ethyl]-N-(2,4-
dimethylthien-3-yl)-acetamide in or on the following commodity:

--------------------------------------------------------------------------
Commodity Parts per million Expiration/revocation date
--------------------------------------------------------------------------
Squash, winter..... 0.01 06/30/09
--------------------------------------------------------------------------

* * * * *
[FR Doc. 06-4161 Filed 5-2-06; 8:45 am]
BILLING CODE 6560-50-S

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