Document ID: EPA-HQ-OPP-2006-0216-0001
Agency: epa
Document Type: Rule
Title: Dimethenamid-p; Pesticide Tolerances for Emergency Exemptions
Posted Date: 2006-05-03T12:41:58Z

[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]

 
Dimethenamid-p; Pesticide Tolerances for Emergency Exemptions

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.epa.gov/edocket/), 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 athttp://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 (65 FR 67249, 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.

0
Therefore, 40 CFR chapter I is amended as follows:

PART 180--[AMENDED]

0
1. The authority citation for part 180 continues to read as follows:

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

0
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