Federal Register / Vol. 77, No. 40 / Wednesday, February 29, 2012 / Rules and Regulations 12207 

regulations in title 40 of the CFR, after 

appearing in the Federal Register, are 

listed in 40 CFR part 9, and included on 

the related collection instrument, or 

form, if applicable. 

C. Regulatory Flexibility Act 

Since this order is not a rule under 

the APA (5 U.S.C. 551(4)), and does 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. 

D. Unfunded Mandates Reform Act; and 

Executive Orders 13132, and 13175 

This order 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 section 

408(n)(4) of FFDCA. 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 order. In 

addition, this order does not impose any 

enforceable duty or contain any 

unfunded mandate as described under 

Title II of the Unfunded Mandates 

Reform Act (UMRA) (2 U.S.C. 1531– 

1538). 

E. Executive Orders 13045, 13211 and 

12898 

As indicated previously, this action is 

not a ‘‘regulatory action’’ as defined by 

Executive Order 12866. As a result, this 

action is not subject to Executive Order 

13045, entitled ‘‘Protection of Children 

from Environmental Health Risks and 

Safety Risks’’, (62 FR 19885, April 23, 

1997) and Executive Order 13211 

entitled ‘‘Actions Concerning 

Regulations That Significantly Affect 

Energy Supply, Distribution, or Use’’, 

(66 FR 28355, May 22, 2001). In 

addition, this order also does not 

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). 

F. National Technology Transfer and 

Advancement Act 

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 

(NTTAA), (15 U.S.C. 272 note). 

IV. Congressional Review Act 

The Congressional Review Act, 5 

U.S.C. 801 et seq. does not apply 

because this action is not a rule as that 

term is defined in 5 U.S.C. 804(3). 

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 10, 2012. 

Steven Bradbury, 

Director, Office of Pesticide Programs. 

Therefore, 40 CFR chapter I is 

amended as follows: 

PART 180—[AMENDED] 

■ 1. The authority citation for part 180 

continues to read as follows: 

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

§ 180.157 [Removed] 

■ 2. Remove § 180.157. 

[FR Doc. 2012–4065 Filed 2–28–12; 8:45 am] 

BILLING CODE 6560–50–P 

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. 

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 


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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)-1Hpyrazol-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-1Hpyrazol-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 


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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-observedadverse-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

Exposure/scenario 

Point of departure and 

uncertainty/safety 

factors 

RfD, PAD, LOC for risk 

assessment 

Study and 

toxicological effects 

Acute dietary (General population 

including infants and children 

and females 13–50 years of 

age).

NOAEL = 100 mg/kg/day .............

UFA = 10x 

UFH = 10x 

FQPA SF = 1x 

Acute RfD = 1 mg/kg/day .............

aPAD = 1 mg/kg/day 

Developmental neurotoxicity in 

rats 

LOAEL = 300 mg/kg/day based 

on decreased brain weight in 

both sexes, reduced thickness 

of the hippocampus, corpus 

callosum, and cerebellum in 

PND 21 female offspring. 


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TABLE 1—SUMMARY OF TOXICOLOGICAL DOSES AND ENDPOINTS FOR PYROXASULFONE FOR USE IN HUMAN HEALTH RISK

ASSESSMENT—Continued 

Exposure/scenario 

Point of departure and 

uncertainty/safety 

factors 

RfD, PAD, LOC for risk 

assessment 

Study and 

toxicological effects 

Chronic dietary (All populations) .... NOAEL= 2 mg/kg/day ...................

UFA = 10x 

UFH = 10x 

FQPA SF = 1x 

Chronic RfD = 0.02 mg/kg/day .....

cPAD = 0.02 mg/kg/day 

1 year chronic dog study LOAEL 

= 10 mg/kg/day based on impaired 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 fooduse 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 nonoccupational, 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. 


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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 shortterm 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 intermediateterm 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 


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12212 Federal Register / Vol. 77, No. 40 / Wednesday, February 29, 2012 / Rules and Regulations 

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 


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Federal Register / Vol. 77, No. 40 / Wednesday, February 29, 2012 / Rules and Regulations 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] 

■ 1. The authority citation for part 180 

continues to read as follows: 

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

■ 2. Section 180.659 is added to subpart 

C to read as follows: 

§ 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)-1Hpyrazol-4-yl]methyl]sulfonyl]-4,5- 

dihydro-5,5-dimethylisoxazole, and its 

metabolite, 5-(difluoromethoxy)-1- 

methyl-3-(trifluoromethyl)-1H-pyrazol4-carboxylic acid (M-3), calculated as 

the stoichiometric equivalent of 

pyroxasulfone, in or on the commodity. 

Commodity Parts per 

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. 

Commodity Parts per 

million 

Corn, field, forage ....................... 0.06 

Commodity Parts per 

million 

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 

DEPARTMENT OF COMMERCE 

National Oceanic and Atmospheric 

Administration 

50 CFR Part 679 

[Docket No. 101126522–0640–02] 

RIN 0648–XB044 

Fisheries of the Economic Exclusive 

Zone Off Alaska; Shallow-Water 

Species by Amendment 80 Vessels in 

the Gulf of Alaska 

AGENCY: National Marine Fisheries 

Service (NMFS), National Oceanic and 

Atmospheric Administration (NOAA), 

Commerce. 

ACTION: Temporary rule; closure. 

SUMMARY: NMFS is prohibiting directed 

fishing for species that comprise the 

shallow-water species fishery by 

Amendment 80 vessels in the Gulf of 

Alaska (GOA). This action is necessary 

because the first seasonal 

apportionment of the sideboard limit for 

2012 Pacific halibut prohibited species 

catch (PSC) specified for the shallowwater species fishery by Amendment 80 

vessels in the GOA has been reached. 

DATES: Effective 1200 hrs, Alaska local 

time (A.l.t.), February 24, 2012, through 

1200 hrs, A.l.t., April 1, 2012. 

FOR FURTHER INFORMATION CONTACT: 

Steve Whitney, 907–586–7269. 

SUPPLEMENTARY INFORMATION: NMFS 

manages the groundfish fishery in the 

GOA exclusive economic zone 

according to the Fishery Management 

Plan for Groundfish of the Gulf of 

Alaska (FMP) prepared by the North 

Pacific Fishery Management Council 

under authority of the MagnusonStevens Fishery Conservation and 

Management Act. Regulations governing 

fishing by U.S. vessels in accordance 

with the FMP appear at subpart H of 50 

CFR part 600 and 50 CFR part 679. 


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