Document ID: EPA-HQ-OPP-2008-0139-0003
Agency: epa
Document Type: Rule
Title: Thiamethoxam; Pesticide Tolerances
Posted Date: 2008-04-18T04:00Z

[Federal Register: April 18, 2008 (Volume 73, Number 76)]
[Rules and Regulations]               
[Page 21043-21049]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr18ap08-8]                         

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 180

[EPA-HQ-OPP-2008-0139; FRL-8359-9]

 
Thiamethoxam; Pesticide Tolerances

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.

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SUMMARY: This regulation establishes tolerances for combined residues 
of the insecticide thiamethoxam and its metabolite, CGA-322704, in or 
on soybean, hulls and soybean, aspirated grain fractions. Syngenta Crop 
Protection, Inc. requested these tolerances under the Federal Food, 
Drug, and Cosmetic Act (FFDCA).

DATES: This regulation is effective April 18, 2008. Objections and 
requests for hearings must be received on or before June 17, 2008, 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-2008-0139. To access the 
electronic docket, go to http://www.regulations.gov, select ``Advanced 
Search,'' then ``Docket Search.'' Insert the docket ID number where 
indicated and select the ``Submit'' button. Follow the instructions on 
the regulations.gov website to view the docket index or access 
available documents. All documents in the docket are listed in the 
docket index available in 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: Julie Chao, Registration Division 
(7505P), Office of Pesticide Programs, Environmental Protection Agency, 
1200 Pennsylvania Ave., NW., Washington, DC 20460-0001; telephone 
number: (703) 308-8735; e-mail address: chao.julie@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

[[Page 21044]]

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

B. How Can I Access Electronic Copies of this Document?

    In addition to accessing an electronic copy of this Federal 
Register document through the electronic docket at http://
www.regulations.gov, you may access this Federal Register document 
electronically through the EPA Internet under the ``Federal Register'' 
listings at http://www.epa.gov/fedrgstr. You may also access a 
frequently updated electronic version of EPA's tolerance regulations at 
40 CFR part 180 through the Government Printing Office's pilot e-CFR 
site at http://www.gpoaccess.gov/ecfr.

C. Can I File an Objection or Hearing Request?

    Under section 408(g) of FFDCA, 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-2008-0139 in the subject line on the first page of 
your submission. All requests must be in writing, and must be mailed or 
delivered to the Hearing Clerk as required by 40 CFR part 178 on or 
before June 17, 2008.
    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 that is described in ADDRESSES. Information not marked 
confidential pursuant to 40 CFR part 2 may be disclosed publicly by EPA 
without prior notice. Submit this copy, identified by docket ID number 
EPA-HQ-OPP-2008-0139, by one of the following methods:
     Federal eRulemaking Portal: http://www.regulations.gov. 
Follow the on-line 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'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. Petition for Tolerance

    In the Federal Register of March 12, 2008 (73 FR 13225) (FRL-8354-
6), EPA issued a notice pursuant to section 408(d)(3) of FFDCA, 21 
U.S.C. 346a(d)(3), announcing the filing of a pesticide petition (PP 
7F7301) by Syngenta Crop Protection, Inc., P.O. Box 18300, Greensboro, 
NC 27419-8300. The petition requested that 40 CFR 180.565 be amended by 
establishing a tolerance for combined residues of the insecticide 
thiamethoxam, 3-[(2-chloro-5-thiazolyl)methyl]tetrahydro-5-methyl-N-
nitro-4H-1,3,5-oxadiazin-4-imine, and its metabolite, CGA-322704,N-(2-
chloro-thiazol-5-ylmethyl) -N'-methyl-N'-nitro-guanidine, in or on 
soybean, hulls at 2.0 ppm and soybean, aspirated grain fractions at 
0.08 ppm. That notice referenced a summary of the petition prepared by 
Syngenta Crop Protection, Inc., the registrant, which is available to 
the public in the docket, http://www.regulations.gov. There were no 
comments received in response to the notice of filing.

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 section 408(b)(2)(D) of FFDCA, and the factors 
specified in section 408(b)(2)(D) of FFDCA, EPA has reviewed the 
available scientific data and other relevant information in support of 
this action. EPA has sufficient data to assess the hazards of and to 
make a determination on aggregate exposure for the petitioned-for 
tolerances for combined residues of the insecticide thiamethoxam, 3-
[(2-chloro-5-thiazolyl)methyl]tetrahydro-5-methyl-N-nitro-4H-1,3,5-
oxadiazin-4-imine, and its metabolite, CGA-322704, N-(2-chloro-thiazol-
5-ylmethyl)-N'-methyl -N'-nitro-guanidine, in or on soybean, hulls at 
2.0 ppm and soybean, aspirated grain fractions at 0.08 ppm. EPA's 
assessment of exposures and risks associated with establishing 
tolerances 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. Specific information on the studies received and the nature 
of the adverse effects caused by thiamethoxam as well as the no-
observed-adverse-effect-level (NOAEL) and the lowest-observed-adverse-
effect-level (LOAEL) from the toxicity studies are discussed in the 
final rule published in the Federal Register of June 22, 2007, (72 FR 
34401) (FRL-8133-6).

B. Toxicological Endpoints

    For hazards that have a threshold below which there is no 
appreciable risk, a toxicological point of departure (POD) is 
identified as the basis for derivation of reference values for risk 
assessment. The POD may be defined as the highest dose at which no 
adverse effects are observed (the NOAEL) in the toxicology study 
identified as appropriate for use in risk assessment. However, if a 
NOAEL cannot be

[[Page 21045]]

determined, the lowest dose at which adverse effects of concern are 
identified (the LOAEL) or a Benchmark Dose (BMD) approach is sometimes 
used for risk assessment. Uncertainty/safety factors (UFs) are used in 
conjunction with the POD to take into account uncertainties inherent in 
the extrapolation from laboratory animal data to humans and in the 
variations in sensitivity among members of the human population as well 
as other unknowns. Safety is assessed for acute and chronic dietary 
risks by comparing aggregate food and water exposure to the pesticide 
to the acute population adjusted dose (aPAD) and chronic population 
adjusted dose (cPAD). The aPAD and cPAD are calculated by dividing the 
POD by all applicable UFs. Aggregate short-, intermediate-, and 
chronic-term risks are evaluated by comparing food, water, and 
residential exposure to the POD to ensure that the margin of exposure 
(MOE) called for by the product of all applicable UFs is not exceeded. 
This latter value is referred to as the Level of Concern (LOC).
    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 
greater than that 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 thiamethoxam used for 
human risk assessment is discussed in Unit Unit III.B. of the final 
rule published in the Federal Register of June 22, 2007 (72 FR 34401) 
(FRL-8133-6).

C. Exposure Assessment

    1. Dietary exposure from food and feed uses. In evaluating dietary 
exposure to thiamethoxam, EPA considered exposure under the petitioned-
for tolerances as well as all existing thiamethoxam tolerances in 40 
CFR 180.565. EPA assessed dietary exposures from thiamethoxam in food 
as follows:
    For both acute and chronic exposure assessments EPA combined 
residues of clothianidin coming from thiamethoxam with residues of 
thiamethoxam per se. As discussed above, thiamethoxam's major 
metabolite is CGA-322704, which is also the registered active 
ingredient clothianidin. There is available information indicating that 
thiamethoxam and clothianidin have different toxicological effects in 
mammals and should be assessed separately, however, these exposure 
assessments for this action incorporated the total residue of 
thiamethoxam and clothianidin to estimate dietary exposure. This 
aggregation of thiamethoxam and clothianidin began with the initial 
assessment of thiamethoxam, prior to the requested registration of 
clothianidin as an active ingredient, and is being maintained in this 
action for historical purposes. In future assessments, as time and 
resources allow, the EPA will provide a rationale for the separate 
analysis of risks coming from thiamethoxam and clothianidin, and will 
conduct separate evaluations of exposure and risk for each chemical. 
The combining of these residues, as was done in these assessments, 
results in highly conservative estimates of dietary exposure and risk.
    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. In estimating acute dietary 
exposure, EPA used food consumption information from the U.S. 
Department of Agriculture (USDA) 1994-1996 and 1998 Nationwide 
Continuing Surveys of Food Intake by Individuals (CSFII). As to residue 
levels in food, EPA assumed maximum residues of thiamethoxam and 
clothianidin observed in the thiamethoxam field trials. It was also 
assumed that 100% of crops with registered or requested uses of 
thiamethoxam are treated. This assumption is highly conservative with 
respect to thiamethoxam use and removes the need to include residues of 
clothianidin coming from the use of that active ingredient.
    ii. Chronic exposure. In conducting the chronic dietary exposure 
assessment EPA used the food consumption data from the USDA 1994-1996 
and 1998 Nationwide CSFII. As to residue levels in food, EPA assumed 
maximum residues of thiamethoxam and clothianidin observed in the 
thiamethoxam field trials. It was also assumed that 100% of crops with 
registered or requested uses of thiamethoxam are treated. This 
assumption is highly conservative with respect to thiamethoxam use and 
removes the need to include residues of clothianidin coming from the 
use of that active ingredient.
    A complete listing of the inputs used in these assessments can be 
found in the document titled ``Thiamethoxam Acute and Chronic Aggregate 
Dietary and Drinking Water Exposure and Risk Assessments for FIFRA 
Section 3 Registration,'' available in the docket EPA-HQ-OPP-2006-0523, 
http://www.regulations.gov.
    iii. Cancer. A quantitative cancer exposure assessment is not 
necessary because EPA concluded that thiamethoxam is ``Not Likely to be 
Carcinogenic to Humans'' based on convincing evidence that a non-
genotoxic mode of action for liver tumors was established in the mouse 
and that the carcinogenic effects are a result of a mode of action 
dependent on sufficient amounts of a hepatotoxic metabolite produced 
persistently. Therefore, the Agency concluded that thiamethoxam is not 
expected to pose a carcinogenic risk and an exposure assessment 
pertaining to cancer risk is not necessary.
    iv. Anticipated residue information. Section 408(b)(2)(E) of FFDCA 
authorizes EPA to use available data and information on the anticipated 
residue levels of pesticide residues in food and the actual levels of 
pesticide residues that have been measured in food. For the present 
action, EPA has used maximum residue values from field trials. These 
trials are designed to produce worst-case residue levels in foods, and 
likely overestimate residues of thiamethoxam and clothianidin that may 
actually occur in or on foods.
    2. Dietary exposure from drinking water. Thiamethoxam is expected 
to be persistent and mobile in terrestrial and aquatic environments. 
These fate properties suggest that thiamethoxam has a potential to move 
into surface water and shallow ground water. The Agency lacks 
sufficient monitoring data to complete a comprehensive dietary exposure 
analysis and risk assessment for thiamethoxam in drinking water. 
Because the Agency does not have comprehensive monitoring data, 
drinking water concentration estimates are made by reliance on 
simulation or modeling taking into account data on the environmental 
fate characteristics of thiamethoxam. 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 the Screening Concentration in Ground Water 
(SCI-GROW) models, the estimated drinking water concentrations (EDWCs) 
of thiamethoxam for acute exposures are estimated to be 12.26 parts per 
billion (ppb) for surface water and 7.94 ppb for ground water. The 
EDWCs for chronic exposures are

[[Page 21046]]

estimated to be 1.29 ppb for surface water and 7.94 ppb for ground 
water.
    The registrant has conducted small-scale prospective ground water 
studies in several locations in the United States to investigate the 
mobility of thiamethoxam in a vulnerable hydrogeological setting. A 
review of those data shows that generally residues of thiamethoxam as 
well as CGA-322704 are below the limit of quantitation (0.05 ppb. When 
quantifiable residues are found, they are sporadic and at low levels. 
The maximum observed residue levels from any monitoring well were 1.0 
ppb for thiamethoxam and 0.73 ppb for CGA-322704. These values are well 
below the modeled estimates summarized above, indicating that the 
modeled estimates are, in fact, protective of what actual exposures are 
likely to be.
    Modeled estimates of drinking water concentrations were directly 
entered into the dietary exposure model. For both the acute and chronic 
assessments the acute EDWC of 12.26 ppb (0.0123 ppm) was used as a 
worst-case estimate of exposure via 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).
    Thiamethoxam is registered for use on turfgrass on golf courses, 
residential lawns, commercial grounds, parks, playgrounds, athletic 
fields, landscapes, interiorscapes and sod farms. Thiamethoxam is 
applied by commercial applicators only. Therefore, exposures resulting 
from homeowner applications were not assessed. However, entering areas 
previously treated with thiamethoxam could lead to exposures for adults 
and children. As a result, risk assessments have been completed for 
postapplication scenarios. Short-term exposures (1 to 30 days of 
continuous exposure) may occur as a result of activities on treated 
turf. There are no use patterns for thiamethoxam that indicate 
intermediate-term (1 to 6 months of continuous exposure) or chronic 
non-dietary exposures are likely to occur.
    Dermal exposures were assessed for adults and children. Oral non-
dietary ingestion exposures (i.e. soil ingestion, and hand-/object-to-
mouth) were assessed for children as well. Since all postapplication 
scenarios occur outdoors the potential for inhalation exposure is 
negligible and therefore does not require an inhalation exposure 
assessment. For purposes of this assessment exposure from residential 
lawns is used to represent the worst case scenario for both dermal and 
oral postapplication exposure.
    Postapplication dermal exposure resulting from contact with treated 
turf was assessed using the EPA's Standard Operating Procedures for 
Residential Exposure and a chemical-specific turf transfer residue 
study.
    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.''
    Thiamethoxam is a member of the neonicotinoid class of pesticides 
and produces, as a metabolite, another neonicotinoid, clothianidin. 
Structural similarities or common effects do not constitute a common 
mechanism of toxicity. Evidence is needed to establish that the 
chemicals operate by the same, or essentially the same sequence of 
major biochemical events (EPA, 2002). Although clothianidin and 
thiamethoxam bind selectively to insect nicotinic acetylcholine 
receptors (nAChR), the specific binding site(s)/receptor(s) for 
clothianidin, thiamethoxam, and the other neonicotinoids are unknown at 
this time. Additionally, the commonality of the binding activity itself 
is uncertain, as preliminary evidence suggests that clothianidin 
operates by direct competitive inhibition, while thiamethoxam is a non-
competitive inhibitor. Furthermore, even if future research shows that 
neonicotinoids share a common binding activity to a specific site on 
insect nicotinic acetylcholine receptors, there is not necessarily a 
relationship between this pesticidal action and a mechanism of toxicity 
in mammals. Structural variations between the insect and mammalian 
nAChRs produce quantitative differences in the binding affinity of the 
neonicotinoids towards these receptors, which, in turn, confers the 
notably greater selective toxicity of this class towards insects, 
including aphids and leafhoppers, compared to mammals. While the 
insecticidal action of the neonicotinoids is neurotoxic, the most 
sensitive regulatory endpoint for thiamethoxam is based on unrelated 
effects in mammals, including effects on the liver, kidney, testes, and 
hematopoietic system. Additionally, the most sensitive toxicological 
effect in mammals differs across the neonicotinoids (e.g., testicular 
tubular atrophy with thiamethoxam; mineralized particles in thyroid 
colloid with imidacloprid). Thus, there is currently no evidence to 
indicate that neonicotinoids share common mechanisms of toxicity, and 
EPA is not following a cumulative risk approach based on a common 
mechanism of toxicity for the neonicotinoids. 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 website 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 prenatal 
and postnatal 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 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. Prenatal and postnatal sensitivity. In the developmental 
studies, there is no evidence of increased quantitative or qualitative 
susceptibility of rat or rabbit fetuses to in utero exposure to 
thiamethoxam. The developmental NOAELs are either higher than or equal 
to the maternal NOAELs. The toxicological effects in fetuses do not 
appear to be any more severe than those in the dams or does. In the rat 
developmental neurotoxicity study, there was no quantitative evidence 
of increased susceptibility.
    There is evidence of increased quantitative susceptibility for male 
pups in both two-generation reproductive studies. In one study, there 
are no toxicological effects in the dams whereas for the pups, reduced 
bodyweights are observed at the highest dose level, starting on day 14 
of lactation. This contributes to an overall decrease in bodyweight 
gain during the entire lactation period. Additionally, reproductive 
effects in males appear in the F1 generation in the form of 
increased incidence and severity of testicular tubular atrophy. These 
data are considered to be evidence of increased quantitative 
susceptibility for male pups (increased incidence of testicular tubular 
atrophy at 1.8

[[Page 21047]]

milligrams/kilogram/day (mg/kg/day) when compared to the parents 
(hyaline changes in renal tubules at 61 mg/kg/day; NOAEL is 1.8 mg/kg/
day).
    In the more recent two-generation reproduction study, the most 
sensitive effect was sperm abnormalities at 3 mg/kg/day (the NOAEL is 
1.2 mg/kg/day) in the F1 males. This study also indicates 
increased susceptibility for the offspring for this effect.
    Although there is evidence of increased quantitative susceptibility 
for male pups in both reproductive studies, NOAELs and LOAELs were 
established in these studies and the Agency selected the NOAEL for 
testicular effects in F1 pups as the basis for risk 
assessment. The Agency has confidence that the NOAEL selected for risk 
assessment is protective of the most sensitive effect (testicular 
effects) for the most sensitive subgroup (pups) observed in the 
toxicological database.
    Due to the finding of quantitative sensitivity in the reproduction 
studies, the EPA conducted a degree of concern analysis to assess the 
residual uncertainties for pre- and/or postnatal susceptibility. The 
Agency concluded that there is low concern for an increased 
susceptibility in the young given:
    i. There was no increased sensitivity (qualitative or quantitative) 
in the rat developmental, rabbit developmental and rat developmental 
neurotoxicity studies.
    ii. There was a clear NOAEL identified for the effects in pups in 
the rat reproduction studies where sensitivity was seen.
    iii. The Agency selected this NOAEL as the basis for risk 
assessment.
    3. Conclusion. The final rule published in the Federal Register of 
January 5, 2006 (http://www.epa.gov/fedrgstr/EPA-PEST/2005/January/Day-
05/p089.htm) reported that the EPA had determined that the 10X special 
safety factor to protect infants and children should be retained for 
thiamethoxam based on the following factors: Effects on endocrine 
organs observed across species; the significant decrease in alanine 
amino transferase levels in the companion animal studies and in the dog 
studies; the mode of action of this chemical in insects (interferes 
with the nicotinic acetyl choline receptors of the insect's nervous 
system); the transient clinical signs of neurotoxicity in several 
studies across species; and the suggestive evidence of increased 
quantitative susceptibility in the rat reproduction study.
    Since that determination, EPA has received and reviewed a 
Developmental Neurotoxicity (DNT) study in rats and an additional 
Reproduction study in rats. Taking the results of this study into 
account, 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 thiamethoxam is complete, including 
acceptable/guideline developmental toxicity, 2-generation reproduction, 
and developmental neurotoxicity studies designed to detect adverse 
effects on the developing organism, which could result from the 
mechanism that may have produced the decreased alanine amino 
transferase levels.
    ii. For the reasons discussed above, there is low concern for an 
increased susceptibility in the young.
    iii. Although there is evidence of neurotoxicity after acute 
exposure to thiamethoxam at doses of 500 mg/kg/day including drooped 
palpebral closure, decrease in rectal temperature and locomotor 
activity and increase in forelimb grip strength, no evidence of 
neuropathology was observed. These effects occurred at doses at least 
fourteenfold and 416-fold higher than the doses used for the acute, and 
chronic risk assessments, respectively; thus, there is low concern for 
these effects since it is expected that the doses used for regulatory 
purposes would be protective of the effects noted at much higher doses.
    iv. There are no residual uncertainties identified in the exposure 
databases. The dietary food exposure assessments were performed based 
on assumption that the maximum residues of thiamethoxam and 
clothianidin observed in the thiamethoxam field trials were remaining 
on crops. Although there is available information indicating that 
thiamethoxam and clothianidin have different toxicological effects in 
mammals and should be assessed separately, the residues of each have 
been combined in these assessments to ensure that the estimated 
exposures of thiamethoxam do not underestimate actual potential 
thiamethoxam exposures. An assumption of 100% crop treated was made for 
all foods evaluated in the assessments. For both the acute and chronic 
assessments the acute EEC of 12.26 ppb (0.0123 ppm) was used as a 
worst-case estimate of exposure via drinking water. Compared to the 
results from small-scale prospective ground water studies where the 
maximum observed residue levels from any monitoring well were 1.0 ppb 
for thiamethoxam and 0.73 ppb for CGA-322704, the modeled estimates are 
protective of what actual exposures are likely to be. Similarly 
conservative Residential SOPs as well as a chemical-specific turf 
transfer residue (TTR) study were used to assess post-application 
exposure to children as well as incidental oral exposure of toddlers. 
These assessments will not underestimate the exposure and risks posed 
by thiamethoxam.

E. Aggregate Risks and Determination of Safety

    EPA determines whether acute and chronic pesticide exposures are 
safe by comparing aggregate exposure estimates to the aPAD and cPAD. 
The aPAD and cPAD represent the highest safe exposures, taking into 
account all appropriate SFs. EPA calculates the aPAD and cPAD by 
dividing the POD by all applicable UFs. For linear cancer risks, EPA 
calculates the probability of additional cancer cases 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 POD to ensure that the MOE called for 
by the product of all applicable UFs is not exceeded.
    1. Acute risk. Using the exposure assumptions discussed in this 
unit for acute exposure, the acute dietary exposure from food and water 
to thiamethoxam will occupy 3% of the aPAD for children 1 to 2 years 
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 exposure to 
thiamethoxam from food and water will utilize 42% of the cPAD for 
children 1 to 2 years old, the population group with greatest exposure. 
Based on the use patterns proposed, chronic residential exposure to 
residues of thiamethoxam is not expected.
    3. Short-term risk. Short-term aggregate exposure takes into 
account residential exposure plus chronic exposure to food and water 
(considered to be a background exposure level).
    Thiamethoxam is currently registered for use that could result in 
short-term residential exposure and the Agency has determined that it 
is appropriate to aggregate chronic food and water and short-term 
exposures for thiamethoxam. The level of concern for the margin of 
exposure (MOE) is 100 for all residential uses (i.e., MOEs less than 
100 indicate potential risks of concern). Using the exposure 
assumptions described in this unit for short-term exposures, EPA has 
concluded that food, water, and

[[Page 21048]]

residential exposures aggregated result in aggregate MOEs of 730 
through 2,800 for all exposure scenarios (dermal exposures, and oral 
non-dietary ingestion) for infants, children and adults.
    4. Intermediate-term risk. Intermediate-term aggregate exposure 
takes into account residential exposure plus chronic exposure to food 
and water (considered to be a background exposure level). There are no 
use patterns for thiamethoxam that indicate intermediate-term (1 to 6 
months of continuous exposure) exposures are likely to occur.
    5. Aggregate cancer risk for U.S. population. The Agency has 
classified thiamethoxam as not likely to be a human carcinogen based on 
convincing evidence that a non-genotoxic mode of action for liver 
tumors was established in the mouse and that the carcinogenic effects 
are a result of a mode of action dependent on sufficient amounts of a 
hepatotoxic metabolite produced persistently. Thiamethoxam is not 
expected to pose a cancer risk.
    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 to thiamethoxam residues.

IV. Other Considerations

A. Analytical Enforcement Methodology

    Adequate enforcement methodology (high-performance liquid 
chromatography/ultraviolet (HPLC/UV) or mass spectrometry (MS)) is 
available to enforce the tolerance expression. The method may be 
requested from: Chief, Analytical Chemistry Branch, Environmental 
Science Center, 701 Mapes Rd., Ft. Meade, MD 20755-5350; telephone 
number: (410) 305-2905; e-mail address: residuemethods@epa.gov.

B. International Residue Limits

    There are no CODEX or Mexican maximum residue limits (MRLs) for 
thiamethoxam. A number of Canadian MRLs exist for this chemical and are 
in accord with U.S. tolerances. The new/revised tolerances established 
by this rule have been derived using the NAFTA Tolerance Harmonization 
Spreadsheet.

V. Conclusion

    Based upon review of the supporting data, EPA has determined that 
tolerance levels for the following crops should be set as follows: 
soybean, hulls at 2.0 ppm; and soybean, aspirated grain fractions at 
0.08 ppm. Therefore, tolerances are established for the combined 
residues of thiamethoxam, 3-[(2-chloro-5-thiazolyl)methyl]tetrahydro-5-
methyl-N-nitro-4H-1,3,5-oxadiazin-4-imine, and its metabolite, CGA-
322704, N-(2-chloro-thiazol-5-ylmethyl)-N'-methyl-N'-nitro-guanidine, 
in or on soybean, hulls at 2.0 ppm and soybean, aspirated grain 
fractions at 0.08 ppm.

VI. Statutory and Executive Order Reviews

    This final rule establishes tolerances under section 408(d) of 
FFDCA 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, 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 under section 408(d) of FFDCA, such as the tolerance in 
this final rule, do not require the issuance of a proposed rule, the 
requirements of the Regulatory Flexibility Act (RFA) (5 U.S.C. 601 et 
seq.) do not apply.
    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 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 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) (Public Law 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: April 9, 2008.
Lois Rossi,
Director, Registration Division, Office of Pesticide Programs.

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

PART 180--[AMENDED]

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

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

0
2. Section 180.565 is amended by alphabetically adding the following 
commodities to the table in paragraph (a) to read as follows:

Sec.  180.565  Thiamethoxam; tolerances for residues.

    (a) * * *

[[Page 21049]]

------------------------------------------------------------------------
                      Commodity                        Parts per million
------------------------------------------------------------------------
                                * * * * *
Soybean, aspirated grain fractions...................               0.08
Soybean, hulls.......................................                2.0
                                * * * * *
------------------------------------------------------------------------

* * * * *

[FR Doc. E8-8398 Filed 4-17-08; 8:45 am]

BILLING CODE 6560-50-S