Document ID: EPA-HQ-OPP-2009-0717-0016
Agency: epa
Document Type: Rule
Title: Pesticide Tolerances: Pyroxasulfone
Posted Date: 2012-03-06T05:00Z

[Federal Register Volume 77, Number 40 (Wednesday, February 29, 2012)]
[Rules and Regulations]
[Pages 12207-12213]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2012-4478]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 180

[EPA-HQ-OPP-2009-0717; FRL-9334-2]

Pyroxasulfone; Pesticide Tolerances

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.

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SUMMARY: This regulation establishes tolerances for residues of 
pyroxasulfone, including its metabolites and degradates, in or on field 
corn, pop corn, and sweet corn commodities. K-I Chemical U.S.A., Inc., 
requested these tolerances under the Federal Food, Drug, and Cosmetic 
Act (FFDCA).

DATES: This regulation is effective February 29, 2012. Objections and 
requests for hearings must be received on or before April 30, 2012, and 
must be filed in accordance with the instructions provided in 40 CFR 
part 178 (see also Unit I.C. of the SUPPLEMENTARY INFORMATION).

ADDRESSES: EPA has established a docket for this action under docket 
identification (ID) number EPA-HQ-OPP-2009-0717. All documents in the 
docket are listed in the docket index available at http://www.regulations.gov. Although listed in the index, some information is 
not publicly available, e.g., Confidential Business Information (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 in the electronic 
docket at http://www.regulations.gov, or, if only available in hard 
copy, at the OPP Regulatory Public Docket in Rm. S-4400, One Potomac 
Yard (South Bldg.), 2777 S. Crystal Dr., Arlington, VA. The Docket 
Facility is open from 8:30 a.m. to 4 p.m., Monday through Friday, 
excluding legal holidays. The Docket Facility telephone number is (703) 
305-5805.

FOR FURTHER INFORMATION CONTACT: Susan Stanton, Registration Division 
(7505P), Office of Pesticide Programs, Environmental Protection Agency, 
1200 Pennsylvania Ave. NW., Washington, DC 20460-0001; telephone 
number: (703) 305-5218 email address: stanton.susan@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 those 
engaged in the following activities:
     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 to 
provide 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

[[Page 12208]]

questions regarding the applicability of this action to a particular 
entity, consult the person listed under FOR FURTHER INFORMATION 
CONTACT.

B. How can I get electronic access to other related information?

    You may access a frequently updated electronic version of EPA's 
tolerance regulations at 40 CFR part 180 through the Government 
Printing Office's e-CFR site at http://ecfr.gpoaccess.gov/cgi/t/text/text-idx?&c=ecfr&tpl=/ecfrbrowse/Title40/40tab_02.tpl.

C. How can I file an objection or hearing request?

    Under the FFDCA section 408(g), 21 U.S.C. 346a, any person may file 
an objection to any aspect of this regulation and may also request a 
hearing on those objections. You must file your objection or request a 
hearing on this regulation in accordance with the instructions provided 
in 40 CFR part 178. To ensure proper receipt by EPA, you must identify 
docket ID number EPA-HQ-OPP-2009-0717 in the subject line on the first 
page of your submission. All objections and requests for a hearing must 
be in writing, and must be received by the Hearing Clerk on or before 
April 30, 2012. Addresses for mail and hand delivery of objections and 
hearing requests are provided in 40 CFR 178.25(b).
    In addition to filing an objection or hearing request with the 
Hearing Clerk as described in 40 CFR part 178, please submit a copy of 
the filing that does not contain any CBI for inclusion in the public 
docket. Information not marked confidential pursuant to 40 CFR part 2 
may be disclosed publicly by EPA without prior notice. Submit a copy of 
your non-CBI objection or hearing request, identified by docket ID 
number EPA-HQ-OPP-2009-0717, by one of the following methods:
     Federal eRulemaking Portal: http://www.regulations.gov. 
Follow the online instructions for submitting comments.
     Mail: Office of Pesticide Programs (OPP) Regulatory Public 
Docket (7502P), Environmental Protection Agency, 1200 Pennsylvania Ave. 
NW., Washington, DC 20460-0001.
     Delivery: OPP Regulatory Public Docket (7502P), 
Environmental Protection Agency, Rm. S-4400, One Potomac Yard (South 
Bldg.), 2777 S. Crystal Dr., Arlington, VA. Deliveries are only 
accepted during the Docket Facility's normal hours of operation (8:30 
a.m. to 4 p.m., Monday through Friday, excluding legal holidays). 
Special arrangements should be made for deliveries of boxed 
information. The Docket Facility telephone number is (703) 305-5805.

II. Summary of Petitioned-For Tolerance

    In the Federal Register of January 6, 2010 (75 FR 864) (FRL-8801-
5), EPA issued a notice pursuant to FFDCA section 408(d)(3), 21 U.S.C. 
346a(d)(3), announcing the filing of a pesticide petition (PP 9F7560) 
by K-I Chemical U.S.A., Inc., c/o Landis International, Inc., P.O. Box 
5126, Valdosta, GA 31603-5126. The petition requested that 40 CFR part 
180 be amended by adding a section for the herbicide pyroxasulfone and 
establishing tolerances therein for residues of pyroxasulfone, 3-[[[5-
(difluoromethoxy)-1-methyl-3-(trifluoromethyl)-1H-pyrazol-4-
yl]methyl]sulfonyl]-4,5-dihydro-5,5-dimethylisoxazole, and its 
metabolites M-1, 5-difluoromethoxy-1-methyl-3-trifluoromethyl-1H-
pyrazol-4-ylmethanesulfonic acid; M-3, 5-difluoromethoxy-1-methyl-3-
trifluoromethyl-1H-pyrazol-4-carboxylic-acid; and M-25, (5-
difluoromethoxy-3-trifluoromethyl-1H-pyrazol-4-yl)methanesulfonic acid 
in or on field corn kernel at 0.01 parts per million (ppm); field corn 
forage at 0.15 ppm; field corn stover at 0.15 ppm; field corn meal at 
0.01 ppm; field corn grits at 0.01 ppm; field corn flour at 0.01 ppm; 
field corn starch at 0.01 ppm; field corn oil (wet and dry milled) at 
0.01 ppm; sweet corn ears at 0.02 ppm; sweet corn forage at 0.15 ppm; 
sweet corn stover at 0.15 ppm; wheat grain at 0.02 ppm; wheat forage at 
0.2 ppm; wheat straw at 0.2 ppm; soybean seed at 0.05 ppm; soybean 
forage at 1.0 ppm; soybean hay at 2.0 ppm; soybean meal at 0.05 ppm; 
soybean hulls at 0.02 ppm; and soybean refined oils at 0.01 ppm. That 
notice referenced a summary of the petition prepared by K-I Chemical 
U.S.A., Inc., the registrant, which is available in the docket, http://www.regulations.gov. There were no comments received in response to the 
notice of filing.
    Based upon review of the data supporting the petition, EPA has 
revised the tolerance expression, commodity terms, and tolerance levels 
for corn commodities. The Agency has also determined that the submitted 
data are not adequate to support tolerances on soybean or wheat 
commodities and is, therefore, not establishing tolerances on these 
commodities at this time. The reasons for these changes are explained 
in Unit IV.C.

III. Aggregate Risk Assessment and Determination of Safety

    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. * * 
*''
    Consistent with FFDCA section 408(b)(2)(D), and the factors 
specified in FFDCA section 408(b)(2)(D), 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 and to make a 
determination on aggregate exposure for pyroxasulfone, including 
exposure resulting from the tolerances established by this action. 
EPA's assessment of exposures and risks associated with pyroxasulfone 
follows.

A. Toxicological Profile

    EPA has evaluated the available toxicity data and considered its 
validity, completeness, and reliability as well as the relationship of 
the results of the studies to human risk. EPA has also considered 
available information concerning the variability of the sensitivities 
of major identifiable subgroups of consumers, including infants and 
children.
    Pyroxasulfone acute toxicity to mammals is low by all routes of 
exposure. Subchronic and chronic oral toxicity testing of pyroxasulfone 
in mice, rats, and dogs produced a variety of adverse effects in 
several target organs. Effects seen in animal studies included cardiac 
toxicity (increased cardiomyopathy in mice and rats), liver toxicity 
(centrilobular hepatocellular hypertrophy, histopathological, and/or 
clinical pathological indicators), neurotoxicity characterized by 
axonal/myelin degeneration in the sciatic nerve (dog, mouse, and rat) 
and spinal cord sections (dog), skeletal muscle

[[Page 12209]]

myopathy, kidney toxicity (increased incidence of chronic progressive 
nephropathy in dogs and retrograde nephropathy in mice), urinary 
bladder mucosal hyperplasia, inflammation, and urinary bladder 
transitional cell papillomas (rats). Decreased body weight and enzyme 
changes were noted in some studies. Immunotoxicity studies in rats and 
mice showed no evidence of immunotoxic effects from pyroxasulfone.
    Pyroxasulfone was moderately toxic to rats following a 4-week 
dermal exposure producing local inflammation and systemic effects of 
minimal to mild cardiac myofiber degeneration at the limit dose. No 
adverse effects were noted in a 28-day inhalation study at the highest-
dose tested.
    Pyroxasulfone did not exhibit developmental toxicity in the rat 
developmental toxicity study and exhibited only slight developmental 
toxicity in rabbits (reduced fetal weight and resorptions) at the limit 
dose. However, developmental effects were noted in post-natal day (PND) 
21 offspring in the rat developmental neurotoxicity (DNT) study 
characterized as decreased brain weight and morphometric changes. 
Developmental effects in the rabbit developmental study and DNT study 
occurred in the absence of maternal toxicity, indicating potential 
increased quantitative susceptibility of offspring. In a reproductive 
toxicity in rats reduced pup weight and body weight gains during 
lactation occurred at similar or higher doses causing pronounced 
maternal toxicity (reduced body weight, body weight gain, and food 
consumption and increased kidney weight, cardiomyopathy, and urinary 
bladder mucosal hyperplasia with inflammation).
    In cancer studies in mice and rats, renal tubular adenomas were 
observed in male mice and urinary bladder transitional cell papillomas 
were observed in male rats. The kidney adenomas in male mice were 
determined to be spontaneous and not treatment-related based on the 
following considerations:
    1. Absence of any cytotoxicity (degeneration or individual cell 
necrosis) in studies ranging from 14 days to 18 months at doses up to 
15,000 ppm.
    2. Absence of cell regeneration leading to precursor lesions such 
as atypical tubular hyperplasia at all time points and doses up to 
15,000 ppm.
    3. Lack of exacerbation of chronic progressive nephropathy, a 
spontaneous disease in rodents that results in cell regeneration which 
can result in renal tubule tumors in chronic studies.
    4. Lack of a clear dose response in the distribution of tumors 
between test substance treated groups.

The urinary bladder tumors seen in male rats were determined to be a 
threshold effect. Pyroxasulfone exposure causes the growth of crystals 
in the urinary tract with subsequent calculi formation resulting in 
cellular damage. Crystal formation in the absence of calculi is not 
associated with hyperplasia or urinary bladder tumors; therefore, the 
formation of urinary bladder calculi is the prerequisite for subsequent 
hyperplasia and neoplasia. In other words, urinary bladder tumors do 
not develop at doses too low to produce calculi. There is also a clear 
threshold of 1,000 ppm (42.55 milligrams/kilogram/day (mg/kg/day)) for 
development of calculi and tumorigenesis. The point of departure (POD) 
of 50 ppm (2.0 mg/kg/day) selected for chronic risk assessment is not 
expected to result in urinary bladder calculi formation, which is a 
prerequisite for subsequent hyperplasia and neoplasia. Therefore, the 
Agency has determined that the quantification of risk using a non-
linear approach (i.e., Reference dose (RfD)) will adequately account 
for all chronic toxicity, including carcinogenicity, that could result 
from exposure to pyroxasulfone. There is no concern for mutagenicity.
    Specific information on the studies received and the nature of the 
adverse effects caused by pyroxasulfone as well as the no-observed-
adverse-effect-level (NOAEL) and the lowest-observed-adverse-effect-
level (LOAEL) from the toxicity studies can be found at http://www.regulations.gov in document ``Pyroxasulfone Human Health Risk 
Assessment for Use of New Active Ingredient Pyroxasulfone on Corn,'' p. 
34, in docket ID number EPA-HQ-OPP-2009-0717.

B. Toxicological Points of Departure/Levels of Concern

    Once a pesticide's toxicological profile is determined, EPA 
identifies toxicological POD and levels of concern to use in evaluating 
the risk posed by human exposure to the pesticide. For hazards that 
have a threshold below which there is no appreciable risk, the 
toxicological POD is used as the basis for derivation of reference 
values for risk assessment. PODs are developed based on a careful 
analysis of the doses in each toxicological study to determine the dose 
at which no adverse effects are observed (the NOAEL) and the lowest 
dose at which adverse effects of concern are identified (the LOAEL). 
Uncertainty/safety factors are used in conjunction with the POD to 
calculate a safe exposure level--generally referred to as a population-
adjusted dose (PAD) or a RfD--and a safe margin of exposure (MOE). For 
non-threshold risks, the Agency assumes that any amount of exposure 
will lead to some degree of risk. Thus, the Agency estimates risk in 
terms of the probability of an occurrence of the adverse effect 
expected in a lifetime. For more information on the general principles 
EPA uses in risk characterization and a complete description of the 
risk assessment process, see http://www.epa.gov/pesticides/factsheets/riskassess.htm.
    A summary of the toxicological endpoints for pyroxasulfone used for 
human risk assessment is shown in Table 1 of this unit.

 Table 1--Summary of Toxicological Doses and Endpoints for Pyroxasulfone for Use in Human Health Risk Assessment
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                                        Point of departure and
          Exposure/scenario               uncertainty/safety     RfD, PAD, LOC for risk         Study and
                                               factors                 assessment         toxicological effects
----------------------------------------------------------------------------------------------------------------
Acute dietary (General population      NOAEL = 100 mg/kg/day..  Acute RfD = 1 mg/kg/day  Developmental
 including infants and children and    UFA = 10x..............  aPAD = 1 mg/kg/day.....   neurotoxicity in rats
 females 13-50 years of age).          UFH = 10x..............                           LOAEL = 300 mg/kg/day
                                       FQPA SF = 1x...........                            based on decreased
                                                                                          brain weight in both
                                                                                          sexes, reduced
                                                                                          thickness of the
                                                                                          hippocampus, corpus
                                                                                          callosum, and
                                                                                          cerebellum in PND 21
                                                                                          female offspring.

[[Page 12210]]

 
Chronic dietary (All populations)....  NOAEL= 2 mg/kg/day.....  Chronic RfD = 0.02 mg/   1 year chronic dog
                                       UFA = 10x..............   kg/day.                  study LOAEL = 10 mg/kg/
                                       UFH = 10x..............  cPAD = 0.02 mg/kg/day..   day based on impaired
                                       FQPA SF = 1x...........                            hind limb function,
                                                                                          ataxia, hind limb
                                                                                          twitching and tremors;
                                                                                          clinical pathology:
                                                                                          Increased creatine
                                                                                          kinase, aspartate
                                                                                          aminotransferase;
                                                                                          axonal/myelin
                                                                                          degeneration of the
                                                                                          sciatic nerve and
                                                                                          spinal cord sections.
                                      --------------------------------------------------------------------------
Cancer (Oral, dermal, inhalation)....  ``Not Likely to be Carcinogenic to Humans'' at doses that do not cause
                                        crystals with subsequent calculi formation resulting in cellular damage
                                        of the urinary tract. Risk is quantified using a non-linear (i.e., RfD)
                                        approach.
----------------------------------------------------------------------------------------------------------------
DNT = neurotoxicity study, FQPA SF = Food Quality Protection Act Safety Factor.
LOAEL = lowest-observed-adverse-effect-level. LOC = Levels of Concern.
mg/kg/day = milligram/kilogram/day. NOAEL = no-observed-adverse-effect-level.
PAD = population adjusted dose (a = acute, c = chronic). PND = post-natal day.
RfD = reference dose. UFA = extrapolation from animal to human (interspecies).
UFH = potential variation in sensitivity among members of the human population (intraspecies).

C. Exposure Assessment

    1. Dietary exposure from food and feed uses. In evaluating dietary 
exposure to pyroxasulfone, EPA considered exposure under the 
petitioned-for tolerances on corn commodities only. EPA is not 
establishing the petitioned-for tolerances on soybean and wheat 
commodities and no other tolerances have previously been established 
for pyroxasulfone. EPA assessed dietary exposures from pyroxasulfone in 
food as follows:
    i. Acute exposure. Quantitative acute dietary exposure and 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. Such effects were identified 
for pyroxasulfone. In estimating acute dietary exposure, EPA used food 
consumption information from the United States Department of 
Agriculture (USDA) 1994-1996 and 1998 Nationwide Continuing Surveys of 
Food Intakes by Individuals (CSFII). As to residue levels in food, EPA 
assumed that 100% of field, pop and sweet corn commodities are treated 
with pyroxasulfone and that residues on these commodities are present 
at tolerance levels, adjusted upward to account for metabolites of 
concern (M-1, M-3, and M-25) that are not included in the tolerance 
expression.
    ii. Chronic exposure. In conducting the chronic dietary exposure 
assessment EPA used the food consumption data from the USDA 1994-1996 
and 1998 CSFII. As to residue levels in food, EPA made the same 
assumptions (adjusted tolerance-level residues and 100 percent crop 
treated (PCT)) as in the acute dietary exposure assessment.
    iii. Cancer. EPA determines whether quantitative cancer exposure 
and risk assessments are appropriate for a food-use pesticide based on 
the weight of the evidence from cancer studies and other relevant data. 
Cancer risk is quantified using a linear or nonlinear approach. If 
sufficient information on the carcinogenic mode of action is available, 
a threshold or non-linear approach is used and a cancer RfD is 
calculated based on an earlier noncancer key event. If carcinogenic 
mode of action data are not available, or if the mode of action data 
determines a mutagenic mode of action, a default linear cancer slope 
factor approach is utilized. Based on the data summarized in Unit 
III.A., EPA has concluded that a nonlinear RfD approach is appropriate 
for assessing cancer risk to pyroxasulfone. Cancer risk was assessed 
using the same exposure estimates as discussed in Unit III.C.1.ii.
    iv. Anticipated residue and PCT information. EPA did not use 
anticipated residue or PCT information in the dietary assessment for 
pyroxasulfone. Tolerance level residues (adjusted upward to account for 
additional metabolites of concern) and 100 PCT were assumed for all 
food commodities.
    2. Dietary exposure from drinking water. The Agency used screening 
level water exposure models in the dietary exposure analysis and risk 
assessment for pyroxasulfone in drinking water. These simulation models 
take into account data on the physical, chemical, and fate/transport 
characteristics of pyroxasulfone. Further information regarding EPA 
drinking water models used in pesticide exposure assessment can be 
found at http://www.epa.gov/oppefed1/models/water/index.htm.
    Based on the Pesticide Root Zone Model/Exposure Analysis Modeling 
System (PRZM/EXAMS) and Pesticide Root Zone Model Ground Water (PRZM 
GW), the estimated drinking water concentrations (EDWCs) of 
pyroxasulfone for acute exposures are estimated to be 17 parts per 
billion (ppb) for surface water and 210 ppb for ground water. EDWCs of 
pyroxasulfone for chronic exposures for non-cancer assessments are 
estimated to be 3.2 ppb for surface water and 174 ppb for ground water.
    Modeled estimates of drinking water concentrations were directly 
entered into the dietary exposure model. For acute dietary risk 
assessment, the water concentration value of 210 ppb was used to assess 
the contribution to drinking water. For chronic dietary risk 
assessment, the water concentration of value 174 ppb was used to assess 
the contribution to drinking 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). Pyroxasulfone is not 
registered for any specific use patterns that would result in 
residential exposure.

[[Page 12211]]

    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.''
    EPA has not found pyroxasulfone to share a common mechanism of 
toxicity with any other substances, and pyroxasulfone does not appear 
to produce a toxic metabolite produced by other substances. For the 
purposes of this tolerance action, therefore, EPA has assumed that 
pyroxasulfone does not have 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 EPA's Web site at http://www.epa.gov/pesticides/cumulative.

D. Safety Factor for Infants and Children

    1. In general. Section 408(b)(2)(C) of FFDCA provides that EPA 
shall apply an additional tenfold (10X) margin of safety for infants 
and children in the case of threshold effects to account for pre-natal 
and post-natal toxicity and the completeness of the database on 
toxicity and exposure unless EPA determines based on reliable data that 
a different margin of safety will be safe for infants and children. 
This additional margin of safety is commonly referred to as the Food 
Quality Protection Act (FQPA) Safety Factor (SF). In applying this 
provision, EPA either retains the default value of 10X, or uses a 
different additional safety factor when reliable data available to EPA 
support the choice of a different factor.
    2. Pre-natal and post-natal sensitivity. The pre-natal and post-
natal toxicity database for pyroxasulfone includes developmental 
toxicity studies in rats and rabbits, a DNT study in rats, and a 2-
generation reproduction toxicity study in rats. As discussed in Unit 
III.A, evidence of increased susceptibility of fetuses and offspring 
was seen in the DNT study and developmental toxicity study in rabbits 
following in utero or post-natal exposure to pyroxasulfone. No 
increased susceptibility was seen in the rat developmental or 
reproduction toxicity studies. In rabbits, developmental toxicity was 
only seen at the limit dose of 1,000 mg/kg/day as reduced fetal weight 
and increased fetal resorptions with a NOAEL of 500 mg/kg/day for these 
effects, compared to no maternal toxicity at these doses. In a DNT 
study in rats, offspring toxicity (decreased brain weight and 
morphometric changes on PND 21) was seen at 300 mg/kg/day compared to 
no maternal toxicity at 900 mg/kg/day. The degree of concern for the 
increased susceptibility seen in these studies is low and there are no 
residual uncertainties based on the following considerations:
    i. The increased susceptibility is occurring at high doses.
    ii. NOAELs and LOAELs have been identified for all effects of 
concern, and thus a clear dose response has been well defined.
    iii. The PODs selected for risk assessment are protective of the 
fetal/offspring effects.
    3. Conclusion. EPA has determined that reliable data show the 
safety of infants and children would be adequately protected if the 
FQPA SF were reduced to 1X. That decision is based on the following 
findings:
    i. The toxicity database for pyroxasulfone is complete.
    ii. Pyroxasulfone is a neurotoxic chemical and there is evidence of 
increased susceptibility of offspring with regard to neurotoxic effects 
in the rat DNT study. There is also evidence of increased 
susceptibility of fetuses/offspring with regard to non-neurotoxic 
effects in the rabbit developmental toxicity study. However, the 
concern for the increased susceptibility is low and EPA did not 
identify any residual uncertainties after establishing toxicity 
endpoints and traditional uncertainty factors (UFs) to be used in the 
risk assessment for pyroxasulfone.
    iii. There are no residual uncertainties in the exposure database. 
The dietary food exposure assessments were performed based on 100 PCT 
and tolerance-level residues (adjusted upward to account for additional 
metabolites of concern not included in the tolerance expression), and 
EPA made conservative (protective) assumptions in the ground and 
surface water modeling used to assess exposure to pyroxasulfone in 
drinking water. These assessments will not underestimate the exposure 
and risks posed by pyroxasulfone.

E. Aggregate Risks and Determination of Safety

    EPA determines whether acute and chronic dietary pesticide 
exposures are safe by comparing aggregate exposure estimates to the 
acute population adjusted dose (aPAD) +and chronic population adjusted 
dose (cPAD). For linear cancer risks, EPA calculates the lifetime 
probability of acquiring cancer given the estimated aggregate exposure. 
Short-, intermediate-, and chronic-term risks are evaluated by 
comparing the estimated aggregate food, water, and residential exposure 
to the appropriate PODs to ensure that an adequate MOE exists.
    1. Acute risk. Using the exposure assumptions discussed in this 
unit for acute exposure, the acute dietary exposure from food and water 
to pyroxasulfone will occupy 4.2% of the aPAD for infants less than 1 
year old, the population group receiving the greatest exposure.
    2. Chronic risk. Using the exposure assumptions described in this 
unit for chronic exposure, EPA has concluded that chronic exposure to 
pyroxasulfone from food and water will utilize 60% of the cPAD for 
infants less than 1 year old, the population group receiving the 
greatest exposure. There are no residential uses for pyroxasulfone.
    3. Short-term risk. Short-term aggregate exposure takes into 
account short-term residential exposure plus chronic exposure to food 
and water (considered to be a background exposure level). A short-term 
adverse effect was identified; however, pyroxasulfone is not registered 
for any use patterns that would result in short-term residential 
exposure. Short-term risk is assessed based on short-term residential 
exposure plus chronic dietary exposure. Because there is no short-term 
residential exposure and chronic dietary exposure has already been 
assessed under the appropriately protective cPAD (which is at least as 
protective as the POD used to assess short-term risk), no further 
assessment of short-term risk is necessary, and EPA relies on the 
chronic dietary risk assessment for evaluating short-term risk for 
pyroxasulfone.
    4. Intermediate-term risk. Intermediate-term aggregate exposure 
takes into account intermediate-term residential exposure plus chronic 
exposure to food and water (considered to be a background exposure 
level). An intermediate-term adverse effect was identified; however, 
pyroxasulfone is not registered for any use patterns that would result 
in intermediate-term residential exposure. Intermediate-term risk is 
assessed based on intermediate-term residential exposure plus chronic 
dietary exposure. Because there is no intermediate-term residential 
exposure and chronic dietary exposure has already been assessed under 
the appropriately protective cPAD (which is at least as protective as 
the POD used to assess intermediate-term risk), no further assessment 
of intermediate-term

[[Page 12212]]

risk is necessary, and EPA relies on the chronic dietary risk 
assessment for evaluating intermediate-term risk for pyroxasulfone.
    5. Aggregate cancer risk for U.S. population. As explained in Unit 
III.A., the Agency has determined that the quantification of risk using 
a non-linear (i.e., RfD) approach will adequately account for all 
chronic toxicity, including carcinogenicity, that could result from 
exposure to pyroxasulfone. Therefore, based on the results of the 
chronic risk assessment discussed in Unit III.E.2., pyroxasulfone is 
not expected to pose a cancer risk to humans.
    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, or to infants and children from aggregate 
exposure pyroxasulfone residues.

IV. Other Considerations

A. Analytical Enforcement Methodology

    Adequate enforcement methodology (a liquid chromatography/mass 
spectrometry/mass spectrometry (LC/MS/MS) method) 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; 
email address: residuemethods@epa.gov.

B. International Residue Limits

    In making its tolerance decisions, EPA seeks to harmonize U.S. 
tolerances with international standards whenever possible, consistent 
with U.S. food safety standards and agricultural practices. EPA 
considers the international maximum residue limits (MRLs) established 
by the Codex Alimentarius Commission (Codex), as required by FFDCA 
section 408(b)(4). The Codex Alimentarius is a joint United Nations 
Food and Agriculture Organization/World Health Organization food 
standards program, and it is recognized as an international food safety 
standards-setting organization in trade agreements to which the United 
States is a party. EPA may establish a tolerance that is different from 
a Codex MRL; however, FFDCA section 408(b)(4) requires that EPA explain 
the reasons for departing from the Codex level.
    The Codex has not established a MRL for pyroxasulfone.

C. Revisions to Petitioned-For Tolerances

    The petitioner proposed tolerances for residues of pyroxasulfone on 
corn, soybean, and wheat commodities. EPA is not establishing the 
proposed tolerances on soybean and wheat commodities at this time due 
to inadequate supporting data. In the case of soybeans, the residue 
analyses from the field trials did not measure the major metabolite M-
28, which comprised approximately 50% of the total residue in soybean 
metabolism studies. Without data on M-28, an appropriate tolerance 
level for soybean cannot be determined. The submitted data for wheat 
were collected from field trials conducted in Australia and, therefore, 
are not considered to be geographically representative of wheat growing 
areas of the United States. Additionally, EPA requires that data be 
collected on wheat hay, and hay data were not collected in any of the 
submitted field trials. Further, the petitioner did not conduct 
processing studies with wheat, so the Agency cannot determine whether 
separate tolerances are needed for the processed commodities of wheat. 
The petitioner must address these deficiencies before the proposed 
soybean and wheat tolerances can be established.
    The petitioner proposed tolerances for residues of pyroxasulfone 
and its metabolites M-1, M-3, and M-25 on ``field corn grain,'' ``field 
corn forage,'' ``field corn stover,'' ``sweet corn ears,'' ``sweet corn 
forage,'' ``sweet corn stover,'' and several processed field corn 
commodities (grits, meal, flour, starch, and oil). EPA has concluded 
that the metabolites M-1, M-3, and M-25 should be included as residues 
of concern for risk assessment purposes for all corn commodities; 
however, to harmonize with its global review partners, Australia and 
Canada, U.S. tolerances for corn grain commodities will be enforced by 
measuring only parent pyroxasulfone and the M-3 metabolite. Tolerances 
for corn forage and stover will be enforced by measuring the parent 
pyroxasulfone and all three metabolites. EPA has determined that the 
proposed tolerances on processed field corn commodities (grits, meal, 
flour, starch, and oil) are unnecessary, since residues on these 
commodities are not expected to exceed those in the raw agricultural 
commodities (RACs) and thus will be covered by the RAC tolerances.
    EPA has revised the commodity terms for all field and sweet corn 
commodities and is establishing tolerances on pop corn commodities, 
separate from those on field corn, as follows to agree with the 
Agency's Food and Feed Vocabulary: ``Corn, field, grain;'' ``Corn, 
field, forage;'' ``Corn, field, stover;'' ``Corn sweet, kernel plus cob 
with husks removed;'' ``Corn, sweet, forage;'' ``Corn, sweet, stover;'' 
``Corn, pop, grain;'' ``Corn, pop, stover.''
    Finally, EPA has revised the tolerance levels for corn grain and 
forage commodities as follows based on analysis of the field trial data 
using the tolerance MRL calculator in accordance with the Organization 
for Economic Cooperation and Development's ``MRL Calculator User Guide 
Standard Operating Procedure (SOP).'' Field (and pop) corn grain was 
increased from 0.01 ppm to 0.015 ppm. Field corn forage was decreased 
from 0.15 ppm to 0.06 ppm. Sweet corn grain was decreased from 0.02 ppm 
to 0.015 ppm. Sweet corn forage was decreased from 0.15 ppm to 0.10 
ppm.

V. Conclusion

    Therefore, tolerances are established for residues of 
pyroxasulfone, 3-[[[5-(difluoromethoxy)-1-methyl-3-(trifluoromethyl)-
1H-pyrazol-4-yl]methyl]sulfonyl]-4,5-dihydro-5,5-dimethylisoxazole, 
including its metabolites and degradates, as set forth in the 
regulatory text.

VI. Statutory and Executive Order Reviews

    This final rule establishes tolerances under FFDCA section 408(d) 
in response to a petition submitted to the Agency. 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 final rule has been 
exempted from review under Executive Order 12866, this final rule is 
not subject to Executive Order 13211, entitled Actions Concerning 
Regulations That Significantly Affect Energy Supply, Distribution, or 
Use (66 FR 28355, May 22, 2001) or Executive Order 13045, entitled 
Protection of Children from Environmental Health Risks and Safety Risks 
(62 FR 19885, April 23, 1997). 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., 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).
    Since tolerances and exemptions that are established on the basis 
of a petition

[[Page 12213]]

under FFDCA section 408(d) 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.
    This final rule directly regulates growers, food processors, food 
handlers, and food retailers, not States or tribes, nor does this 
action alter the relationships or distribution of power and 
responsibilities established by Congress in the preemption provisions 
of FFDCA section 408(n)(4). As such, the Agency has determined that 
this action will not have a substantial direct effect on States or 
tribal governments, on the relationship between the national government 
and the States or tribal governments, or on the distribution of power 
and responsibilities among the various levels of government or between 
the Federal Government and Indian tribes. Thus, the Agency has 
determined that Executive Order 13132, entitled Federalism (64 FR 
43255, August 10, 1999) and Executive Order 13175, entitled 
Consultation and Coordination with Indian Tribal Governments (65 FR 
67249, November 9, 2000) do not apply to this final rule. In addition, 
this final rule does not impose any enforceable duty or contain any 
unfunded mandate as described under Title II of the Unfunded Mandates 
Reform Act of 1995 (UMRA) (Pub. L. 104-4).
    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).

VII. Congressional Review Act

    The Congressional Review Act, 5 U.S.C. 801 et seq., generally 
provides that before a rule may take effect, the agency promulgating 
the rule must submit a rule report 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 the Federal 
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: February 15, 2012.
Steven Bradbury,
 Director, Office of Pesticide Programs.

    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 180.659 is added to subpart C to read as follows:

Sec.  180.659  Pyroxasulfone; tolerances for residues.

    (a) General. (1) Tolerances are established for residues of the 
herbicide pyroxasulfone, including its metabolites and degradates, in 
or on the commodities in the table below. Compliance with the tolerance 
levels specified below is to be determined by measuring only the sum of 
pyroxasulfone, 3-[[[5-(difluoromethoxy)-1-methyl-3-(trifluoromethyl)-
1H-pyrazol-4-yl]methyl]sulfonyl]-4,5-dihydro-5,5-dimethylisoxazole, and 
its metabolite, 5-(difluoromethoxy)-1-methyl-3-(trifluoromethyl)-1H-
pyrazol-4-carboxylic acid (M-3), calculated as the stoichiometric 
equivalent of pyroxasulfone, in or on the commodity.

------------------------------------------------------------------------
                                                               Parts per
                          Commodity                             million
------------------------------------------------------------------------
Corn, field, grain..........................................       0.015
Corn, pop, grain............................................       0.015
Corn, sweet, kernel plus cob with husks removed.............       0.015
------------------------------------------------------------------------

     (2) Tolerances are established for residues of the herbicide 
pyroxasulfone, including its metabolites and degradates, in or on the 
commodities in the table below. Compliance with the tolerance levels 
specified below is to be determined by measuring only the sum of 
pyroxasulfone, 3-[[[5-(difluoromethoxy)-1-methyl-3-(trifluoromethyl)-
1H-pyrazol-4-yl]methyl]sulfonyl]-4,5-dihydro-5,5-dimethylisoxazole, and 
its metabolites, 5-(difluoromethoxy)-1-methyl-3-(trifluoromethyl)-1H-
pyrazol-4-yl]methanesulfonic acid (M-1); 5-(difluoromethoxy)-1-methyl-
3-(trifluoromethyl)-1H-pyrazol-4-carboxylic acid (M-3); and [5-
(difluoromethoxy)-3-(trifluoromethyl)-1H-pyrazol-4-yl]methanesulfonic 
acid (M-25), calculated as the stoichiometric equivalent of 
pyroxasulfone, in or on the commodity.

------------------------------------------------------------------------
                                                               Parts per
                          Commodity                             million
------------------------------------------------------------------------
Corn, field, forage.........................................        0.06
Corn, field, stover.........................................        0.15
Corn, pop, stover...........................................        0.15
Corn, sweet, forage.........................................        0.10
Corn, sweet, stover.........................................        0.15
------------------------------------------------------------------------

     (b) Section 18 emergency exemptions. [Reserved]
    (c) Tolerances with regional registrations. [Reserved]
    (d) Indirect or inadvertent residues. [Reserved]

[FR Doc. 2012-4478 Filed 2-28-12; 8:45 am]
BILLING CODE 6560-50-P