EPA REGISTRATION DIVISION CO MPANY NOTICE OF FILING FOR

PESTICIDE PETITIONS PUBLISHED IN THE FEDERAL REGISTER

EPA Registration Division contact: [ Kathryn Montague (703) 305-1243]

INSTRUCTIONS: Please utilize this outline in p reparing the pesticide petition. In

cases where the outline element does not apply, please insert “NA-Remove” and

maintain the outline. Please do not chan ge the margins, font, or format in your pesticide petition. Simply replace the instructions that appear in green , i.e., “ [insert company name] ,” with the information specific to your action.

TEMPLATE:

[Bayer CropScience]

[Insert petition number]

EPA has received a pesticide petition ([insert petition number]) from [BayerCropScience], [2 T.W. Alexander Dr ive, Research Triangle Park, NC, 27709] proposing, pursuant to section 408(d) of the Federal Food, Drug, and Cosmetic Act (FFDCA), 21 U.S.C. 346a(d), to amend 40 CFR part 180. 537(a)

(Options (pick one)

1. by establishing a tolerance for residues of

[the herbicide isoxaflutole [5-cyc lopropyl-4-(2-methylsulfonyl-4- trifluoromethylbenzoyl) isoxazole] and its metabolite 1-(2-methylsulphonyl-4- trifluoromethylphenyl)-2-cyano-3-cycl opropyl propane -1,3-dione (RPA 202248), calculated as the parent compound

, in or on the raw agricultural commodity [soybean, at [0.05] and soybean, aspira ted grain fractions at 0.25] parts per million (ppm). EPA has determined that the petiti on contains data or informati on regarding the elements set forth in section 408 (d)(2) of FDDCA; however, EPA has not fully evaluated the sufficiency of the submitted data at this tim e or whether the data supports granting of the petition. Additional data may be needed before EPA rules on the petition.

A. Residue Chemistry

1. Plant metabolism. [The nature of the residue in plants and animals following exposure to isoxafluto le is understood. In plants, the first metabolic step is opening of the isoxazole ring of isoxaflutole to afford RPA 202248. This metabolite then undergoes hydrolysis to produ ce RPA 203328. In animals, metabolism of M-385623-Ü1-12

isoxaflutole proceeds in a similar pathway via opening of the isoxazole ring to RPA 202248 and RPA 205834. These metabolites undergo further hydrolysis to produce RPA 207048 and RPA 203328. The residues of regulatory concern in plant and animal tissues are the parent compound, isoxaflutole, and its metabolite, RPA 202248.]

2. Analytical method. [Bayer CropScience has submi tted a method description and validation for an LC-MS/MS (CAL study # 019-03) for use in corn and rotational crops. This method is the prop osed enforcement method for all crops. A modification of this method, IS-004-P10- 02 was developed and validated for use in the soybean field trials. In method IS -004P10-02, isoxaflutole and IFT-DKN are extracted from plant matrices by adding an acidic methanol/water solution to an aliquot of plant matrix followed by blending. An isotopic internal standard is added to the extract and the sample is capped an d mixed. The sample is then diluted 1:1 with 0.1% formic acid in water, placed in a vial and an aliquot analyzed by tandem mass spectrometry (LC/MS/MS). Quantificati on was based on the use of internal standards and comparison of peak areas with those of known standards. The detection by MS/MS was performed on a triple-quadrupole tandem mass spectrometer, equipped with a Turbo IonSpray (ESI) interface operated in positive ion mode and multiple reaction monitoring (MRM). A confirmatory transition is provided for use as necessary. The initial extr action for this method is similar to the previously submitted GC/MSD method wh ich has been radio-validated. The radiovalidation data demonstrated that the meth od adequately recovers aged residues of isoxaflutole and its metabolites. Average concurrent recoveries for isoxaflutole and

IFT-DKN were within 70% to 120% in s oybean seed at 0.01 (LLMV) and 0.10 ppm. The limit of quantitation is 0.01 ppm for bo th compounds and the limit of detection is 0.0008 ppm for IFT and 0.0017 ppm for IFT-DKN. The method has been shown to be specific for the target analytes and includes confirmatory ion-transitions.]

3. Magnitude of residues. [The soybean varieties used as described in the following summary are tolerant to isoxaflu tole. Field residue trials (20) were conducted to explore 3 different applicatio n patterns in soybeans . In each trial, Isoxaflutole 480 SC containing 4 lb ai/gal (480 g ai/L), was applied to soybean plots at 0.094 lb/A (105 g/ha) pre-emergent (either pre-plant, preplant incoroporated or post plant prior to emergence), at the V3 gr owth stage (3rd trifoliate unfolded) or at or before the R1 growth stage (beginning flowering). Soybean seeds were analyzed

for isoxaflutole and IFT-DKN residues. B ayer CropScience proposes to off label harvesting soybean forage and hay and theref ore, these matrices were not analyzed.

In all treatments, parent isoxaflutole residues were <LOQ and often <LOD. Total isoxaflutole resdiues (parent + IFT-DKN) were <LOQ when isoxaflutole is applied preplant or pre-emergent. The maximum total isoxaflut ole residues were slightly greater than 0.01 ppm when isoxaflutole was applied at the V3 growth stage. Residues increased when applied at the R1 growth stage (first bloom).3

In a processing study conducted at 5X the maximum rate (0.468 lb ai or 525 g ai/ha)

isoxaflutole and its metabolite did not con centrate into hulls, oil or soymilk (<1X processing factor). Isoxaflutole and its meta bolite concentrated slightly into soybean meal (1.21X processing factor), but this fa ctor is less than the theoretical factor (2.2X) and the apparent required tolerance is less than the proposed tolerance for the RAC. Therefore, no separate toleran ces are proposed for soybean processed fractions. In the same processing st udy conducted at 5X the maximum rate,

isoxaflutole and its metabolite did con centrate into soybean aspirated grain fractions (7.26X). A separate tolerance for aspirated grain fractions is proposed at 0.25 ppm]

B. Toxicological Profile

1. Acute toxicity. [The developmental LOAEL of 5 mg/kg/day from the developmental toxicity study in rabbits ha s been identified as the acute dietary endpoint to be used in risk assessments for the sub-population females (13-49 years old). Because of the use of a LOAEL, an unc ertainty factor of 3X in addition to the conventional safety factor of 100X to acco unt for inter- and intra-species variations was applied for risk assessment. Applicat ion of these uncertainty factors to the LOAEL of 5 mg/kg/day was used to derive the acute reference dose (aRfD) of 0.02 mg/kg. EPA also identified the NOA EL of 125 mg/kg/day from the acute neurotoxicity study as the endpoint of conc ern to be used in acute dietary risk assessment for the general population in cluding infants and children. EPA has applied a uncertqainty factor of 100 (10 for interspecies extrapolation and 10x for intraspecies variability) to the NOAEL of 125 mg/kg/day to derive an acute reference dose of 1.25 mg/kg for the general population

. ]

2. Short and Intermediate Term Toxicity . [The short and intermediate – term

dermal and inhalation risks have b een addressed by using a LOAEL of 5.0 mg/kg/day, based on increased incidence of fetuses with the 27th pre-sacral vertebrae. A 3.5% dermal absorption fa ctor was applied and a 100% inhalation absorption factor was assumed. A body weig ht of 60 kg was used since the endpoints selected were from the developmental toxi city studies with demonstrated fetal effects. The level of concern (LOC) for isoxaflutole occupational dermal and inhalation exposures is 300 (i.e., a margin of exposure <300 represents a risk of concern.]

3. Genotoxicty. [A Salmonella sp. reverse gene mutation assay, a mouse lymphoma forward gene mutation assay, an in vitro cytogenetic assasy in cultured human lymphocytes, and a mouse micronucleus assay conducted using isoxaflutole were negative and provided no evidence of mutagenicity.]

4. Reproductive and developmental toxicity. [In a developmental toxicity study,

technical isoxaflutole was administered to female Sprague-Dawley rats by gavage at dose levels of 0, 10, 100 or 500 mg/kg/day be tween days 6 through 15 of gestation. The maternal LOAEL is 500 mg/kg/day base d on increased incidence of clinical4

signs and decreased body weights, body weight gains and food consumption. The maternal NOEL is 100 mg/kg/day. The developmental LOAEL is 100 mg/kg/day based on decreased fetal body weights and increased incidences of skeletal anomalies. The developmental NOEL is 10 mg/kg/day. Isoxaflutole demonstrated no evidence of teratogenicity in this assay. In a developmental toxicity study, technical

isoxaflutole was administered to female New Zealand white rabbits by gavage at dose levels of 0, 5, 20 or 100 mg/kg/day from days 6 th rough 19 of gestation. The maternal LOAEL is 100 mg/kg/day based on increased clinical signs and decreased body weight gains and food consumptio n. The maternal NOEL is 20 mg/kg/day

. The developmental toxicity LOAEL is considered by EPA to be 5 mg/kg/day based on increased incidence of fetuses with 27th pre-sacral vertebrae, a very common

variation in rabbits. Isoxaflutole demonstr ated no evidence of teratogenicity. In a 2- generation reproduction study, technical is oxaflutole was administered to rats at dose levels of 0, 0.5, 2, 20 or 500 mg/kg/d ay (actual levels in males: 0, 0.45, 1.76, 17.4 or 414 mg/kg/day; females: 0, 0.46, 1.79, 17.7 or 437 mg /kg/day, respectively). The parental systemic LOAEL is 17.4 mg/kg/ day for males and females based on increased liver weights and hypertroph y. The parental systemic NOEL is 1.76 mg/kg/day for males and females. The reproductive LOAEL is greater than 437 mg/kg/day based on the lack of reproduc tive effects. The reproductive NOEL is greater than or equal to 437 mg/kg/d ay. Overall, developmental toxicity was observed in rats and rabbits primarily as growth retardations, including delays in skeletal ossification, effects that have b een observed with other HPPD inhibitors. There was no evidence of reproductive toxicity in the two-generation reproductive toxicity study in rats; however, both adul ts and offspring exhibi ted ocular and liver toxicities as seen in similar long-term studies. In the acute and subchronic neurotoxicity studies in rats, mild change s in FOB parameters (grip strength and/or landing foot splay) were observed in adul t animals. However, similar effects were not observed in either pregnant animals or in offspring in the DNT study in rats. In both maternal animals and offspring, ch anges in body weight and/or food consumption were the primary effects seen in the DNT study and at the same dose (highest dose tested only). Decreased br ain weights were observed in offspring on PND11 at the high dose only, but not at a la ter time point, which is an indicator of a developmental delay and/or a secondary effect of the decreased body weight also observed in the offspring. There were no ef fects on pup swimming ability, learning, memory, motor activity, or auditory startl e response at any dose, nor was there any evidence of neuropathology in the study at any dose.]

4. Subchronic toxicity. [In a 21-day dermal toxicity study, technical

isoxaflutole was administered to male and female rats at doses of 0, 10, 100 and 1000 mg/kg/day (8-hour exposure/day, 7 days/week). No clinical signs or effects on body weight, food consumption, hematology, c linincal chemistry or opthalmology were observed. A slight but statistically signific ant increase in liver weight was noted for females (absolute and relative) and for males (relative only) at 1000 mg/kg/day. This finding was considered as an adapti ve response to isoxaflutole treatment. Therefore, the no observed adverse effect level (NOA EL) for sub-acute dermal exposure to isoxaflutole is 1000 mg/kg/d ay or greater for males and females.]5

In a sub-chronic neurotoxicity study, techni cal isoxaflutole was administered to rats at dietary levels of 0, 25, 250 and 750 mg/k g/day for 90 days. Treatment related effects observed in high-dose males were de creases in body weig ht and body weight gain. The LOEL was established at 750 mg /kg/day. The NOEL wa s 250 mg/kg/day.]

5. Chronic toxicity. [ A 2-year combined chronic feeding/carcinogenicity study in rats in which the NOAEL was 2 mg/k g/day and the LOAEL was 20 mg/kg/day based on hepatoxicity, thyroid, ocular eff ects in males and hepatoxicity in females. An uncertainty factor of 100 was used to account for inter- and intra-species variation. Application of this uncertainty fa ctor to NOAEL resulted in the chronic reference dose (cRfD) of 0.02 mg/kg/day.]

6. Animal metabolism. [In a metabolism study, 14C-isoxaflutole was administered to groups of male and female rats (five/sex/dose) at a single low oral dose (1 mg/kg), a repeated low oral dose (1 mg/kg as a final do se in a 15 day repeat dose series) and a single high dose (100 mg/kg). In addition, pharmacokinetics in blood was evaluated using 2 groups of 10 ra ts each that received a single low oral dose of 1 or 100 mg/kg of 14C-isoxaflutole. Urine and feces were collected at 24, 48, 96, 120, 144 and 168 hours after dosing and ti ssues were collected at 168 hours postdosing. Isoxaflutole was rapidly and exte nsively absorbed and metabolized. RPA 202248, a major metabolite, represented 70% or more of the radi oactivity excreted

in the urine and feces from the two lowe st dose groups. A minor metabolite, RPA 203328, was more polar. Elimination was rapi d and dose dependent. The mean total recovery of the radiolabel was 99.2%. Urin ary elimination was predominant in the two low dose groups while the major portion of radiolabel was excreted via the feces in the high dose group. The higher feca l elimination possibly resulted from the saturation of absorption resulting in el imination of unchanged parent compound. The majority of the radiolabel was elimin ated in the first 24 and 48 hours for the low and high dose groups, with an estima ted mean blood half-life of 60 hours. No

sex differences were observed in the metabolism of 14C-isoxaflutole.]

7. Metabolite toxicology

. [RPA 202248. In acute oral toxicity study, RPA

202248 had an oral LD 50 greater than 2000 mg/kg (category III) in the rat. In an Ames assay, RPA 202248 was found to be de void of mutagenic activity in the presence and absence of metabolic activation.

8. Endocrine disruption

. [No special studies have been conducted to investigate the potential of isoxaflutole to induce estrogenic or other endocrine effects. However, no evidence of estrogenic or other endocrine effects have been noted in any of the standard toxicology studies that have been conducted with this product and there is no reason to suspect that any such effects would be likely.]6

C. Aggregate Exposure

1. Dietary exposure. [Tolerances are currently established under 40 CFR

Section 180.537 for combined residues of the herbicide isoxaflutole and its

metabolite RPA 202248 calculated as the parent compound, in or on field corn grain, forage (stover), and fodder. Associat ed tolerances are also established on the liver of cattle, goats, horses, poultry, and sheep. Bayer CropScience is requesting to

revise the established tolerances for isoxaflu tole by adding tolerances for soybean raw agricultural commodities. There are no residential uses proposed for

isoxaflutole. Potential human risk scenar ios, therefore, cover aggregate exposure from food residues and drinking water.]

Food & Water. Acute, chronic and cancer dietary (food plus water) risk

assessments were conducted for the U.S. using DEEM-FCIDTM, Version 2.14, which uses food consumption data from USDA’s Continuing Sur veys of Food Intakes by Individuals (CSFII) from 1994-1996 and 1998. Tier 1 acute, chronic and cancer dietary exposure assessments were cond ucted using the following data and assumptions:

 Maximum residue value from fiel d trial data (0.0055ppm for corn grain and 0.04 ppm for soybeans)

 No concentration in processed fractions

 Drinking water values from FI RST: 7.29ppb acute and 2.54ppb for

chronic

 Secondary residues are not required

The estimated acute dietary (food and wat er) exposure calculations to isoxaflutole residues and associated dietary risk ex pressed as a percentage of the acute population adjusted dose (%aPAD) resul ts in a value of 0.03 % for the US population, 0.12% for infants, 0.06% for children 1-2 and children 3-5 years of age and 1.9 % for females ages 13 to 49. The esti mated chronic dietary (food and water) exposure to isoxaflutole residues of concern and associated dietary risk expressed as a percentage of the chronic population adjust ed dose (%cPAD) results in a value of 0.4 % for the US population, 1.2% for infa nts, 0.69% for children 1-2 years of age,

0.67% for children 3-5 and 0.35 % for females 13 to 49 years of age.

The cancer risk estimate for the US population is 2.99 x 10-7 and 9.09 x 10-7 for food and food + water respectively. The Tier One risk assessment which used maximum residue values, 100% crop treate d and conservative modeled drinking water concentrations, gave acceptable risk estimates for all populations examined

for the acute and chronic scenarios. Th e cancer risk for the US Population was below 1 x 10 -6.]

2. Non-dietary exposure

. [Isoxaflutole products are not labeled for residential uses (food or non-food), thereby eliminating the potential for residential exposure or7

non-occupational exposure.]

D. Cumulative Effects [Section 408(b)(2)(D)(v) requires that, when considering whether to establish, modify, or revoke a tolerance, the Agency consider “available information” concerning the cumulative effe cts of a particular pesticide’s residues

and “other substances that have a commo n mechanism of toxicity.” There are no

available data to determine whether isoxaflutole has a common mechanism of toxicity with other substances or how to in clude this pesticide in a cumulative risk assessment. For the purposes of this petiti on filing, therefore, it has been assumed that isoxaflutole does not have a common mechanism of toxicity with other substances.]

E. Safety Determination

1. U.S. population. [Based on the completeness a nd reliability of the toxicity data, it is concluded that dietary risk from the propos ed uses of isoxaflutole are acceptable for all populations. Chronic ex posure (non-cancer) for the US Population (food and water) utilizes <0.4% (0.00008 mg/kg bw/day) of the chronic PAD. The cancer risk estimate for the US populat ion is 2.99 x 10-7 and 9.09 x 10-7 for food and food + water respectively, which is belo w 1 x 10 -6. Acute exposure for the US Population utilizes 0.03% of the acute PAD (0.000422 mg/bw/day). The most highly exposed population for the acute scenarios is the Female 13 to 49 years of age population subgroup which utilizes 1.9% (food and water) of the acute PAD (0.00038 mg/bw/day).] The most highly exposed population subgroups for the chronic scenario (food and water) are ch ildren 1-2 (0.69% of the chronic PAD, 0.000137 mg/bw/day), children 3-5 (0.67% of the chronic PAD, 0.000133 mg/bw/day), and infants at 1.2% (0.000239 mg /bw/day) of the chronic PAD. EPA generally has no concern for exposures below 100% of the PAD (acute or chronic), because the PAD represents the level at or below which exposure will not pose appreciable risk to human health. An es timated lifetime can cer risk below 1.0x10-6 is considered acceptable for the US Popul ation. Therefore there is a reasonable certainty that no harm will occur to th e US Population from aggregate exposure (food and drinking water) to residues of isoxaflutole. ]

2. Infants and children. [ The most highly exposed population subgroups for the chronic scenario (food and water) are ch ildren 1-2 (0.69% of the chronic PAD, 0.000137 mg/bw/day), children 3-5 (0.67% of the chronic PAD, 0.000133 mg/bw/day), and infants at 1.2% (0.0002 39 mg/bw/day) of the chronic PAD. Children 1-6, Children 7-12 and non-nursing infants for the chronic analysis. Less

than 3% of the chronic PAD was utilized by all three subgroups. Acute and chronic exposures for infants and children are far below 100% of the PAD (acute or chronic). Since the PAD represents a scient ifically determined level at or below which exposure will not pose appreciable risk to human health there is a reasonable certainty that no harm will occur to thes e sub-populations from aggregate exposure (food and drinking water) to residues of isoxaflutole.]8

F. International Tolerances. [Maximum residue limits (MRLs) for isoxaflutole and

metabolites in or on corn commodities have not been established by the Codex

Alimentarius Commission. Maximum residue limits have been established in Canada for the combined residues of isoxaflutole and its metabolites at 0.1 ppm for soybean and at 0.2 ppm for corn, 0.01 ppm for eggs, 0.5 ppm for liver of cattle, 0.3 ppm for liver of poultry, 0.1 ppm for meat byproducts of cattle, horses, hogs, poultry and sheep, 0.2 ppm for meat of catt le, horses, hogs, poultry and sheep and 0.02 ppm for milk. PMRA Canada has a pending proposal to revise the existing MRLs (i.e., removing the IFT-benzoic acid metabolite from the tolerance expression) to 0.02 ppm in field corn grain. Maximum residue limi ts have also been established by Japan for cereal grains (inc luding rice) at 0.05 ppm, corn (including pop corn and sweet corn) at 0.1 ppm, su garcane at 0.01 ppm, legumes/pulses at 0.03 ppm, livestock (cattle, pig and other terrestrial mammals) meat and fat at 0.2 ppm, liver at 0.4 ppm, milk at 0.03 ppm, edible offal at 0.08 pp m, poultry at 0.08 ppm and chicken and other poultry eggs at 0.02 ppm. MRLs are also established for

isoxaflutole in Australia for maize at 0.1 ppm, sugarcane at 0.01 ppm and in Brazil for maize at 0.01 ppm, sugarcane at 0.08 ppm. MRLs also are esta blishd in Morocco and Montenagro for maize at 0.05 ppm. The revised/pending MRL for parent IFT and the DKN metabolite in the EU for corn grain will be 0.02 ppm.]