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EPA REGISTRATION DIVISION COMPANY NOTICE OF FILING FOR

PESTICIDE PETITIONS PUBLISHED IN THE FEDERAL REGISTER

EPA Registration Division contact: William Cutchin 703

- 305

- 7990

Jeneil Biosurfactant Company

I N

- 10848

EPA has r eceived a pesticide petition ( IN

- 10848 ) from Jeneil Biosurfactant Company, 400 N. Dekora Woods Blvd. Saukville, WI 53080 request ing, 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 to establish an exemption from the requirement of a

tolerance for me thyl isobutyrate ( CAS No. 547

- 63

- 7 ) when used as an inert solvent applied to growing crops or harvested crops under 40 CFR 180.910 in pesticide

formulations

. EPA has determined that the pe tition contains data or information 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 time 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. NA

2. Analytical method. NA

3. Magnitude of residues. NA

B. Toxicological Profile

There was little in the toxicity database of methyl isobutyrate. Str ucturally similar compounds were employed as read

- across substances, including isobutyl isobutyrate, which was categorized by the Joint FAO/WHO Expert Committee on Food Additives (JECFA) into the same category as methyl isobutyrate, esters of aliphatic acy clic primary

alcohols with branched chain aliphatic acyclic acids. Compounds in this category are natural components of a wide variety of foods and are metabolized by the carboxylesterases that hydrolyze them to component alcohols and carboxylic acids in t he intestines, blood, and liver. In the case of methyl isobutyrate, the alcohol metabolite is methanol and for isobutyl isobutyrate, it is isobutanol. The acid metabolite in both cases is isobutyric acid.2

JECFA carried out a structural assessment of met hyl isobutyrate toxicity using the

method of Cramer, a peer

- reviewed approach to classifying chemicals with respect to

non

- cancer risk from oral exposure. It primarily uses information on the toxicity of a

chemical's substructures and the predicted pathway of mammalian metabolism. Other

factors in the classification include whether the compound occurs naturally in the body and in food. The Expert Committee reviewed methyl isobutyrate as a member of the

group esters of aliphatic acyclic primary alcohols with branched chain aliphatic acyclic acids, and determined that methyl isobutyrate and the other 31 compounds in this group belong in Cramer Structural Class I, the class of lowest concern, based on the absence of substructures associated with toxicity, an ef ficient metabolic pathway, and the fact that it is an endogenous chemical in food.

1. Acute toxicity. An LD 50 value of 16,000 mg/kg/ bw was determined in rats for methyl isobutyrate. The LC 50 of methyl isobutyrate was reported to be 25.5 mg/L in

mice. The se correspond to acute t oxicity c ategory of IV for oral and inhalation routes of exposure. No further information was available on this compound's acute toxicity. The structurally similar compound isobutyl isobutyrate, which was also in the JECFA group

est ers of aliphatic acyclic primary alcohols with branched chain aliphatic acyclic acids, was Toxicity Category IV for dermal acute toxicity indicating low dermal toxicity potential.

2. Genotoxicty. Methyl isobutyrate did not significantly induce chromosome loss

in mitotically growing Saccharomyces cerevisiae D61.M cells, without the presence of a

known inducer. The structurally similar isobutyl isobutyrate did not induce reverse

mutations in Salmonella typhimurium strains TA98, TAIOO, TA1535, and TA1537, or in

Escherichia coli strain WP2 uvrA at concentrations as high as 5000 u g/mL in the absence or presence of metabolic activation.

An evaluation of the structure of methyl isobutyrate for alerts to genotoxicity yields no identifiable structures of concern. A "structural alert" is defined as a molecular

substructure with a high correlation (>90% overall) to mutagenicity. The structural alert QSAR analysis is derived from data from 44 substructures and mutagenicity data from

over 4000 chemicals f rom National Toxicology Program's (NTP) database and the Japanese Industrial Safety and Health Law (ISHL) database. None of the substructures are found in methyl isobutyrate, suggesting that is unlikely to be genotoxic.

3. Reproductive and developmental toxicity. In two prenatal developmental toxicity inhalation studies, mated female Wistar rats and Flimalayan rabbits were exposed to isobutanol (99.8%) at vapor concentrations of 0,151, 758 or 3030 ppm (0, 500, 2,500 or 10,000 mg/m 3 ) for six hours/day. The rats were do sed on post

- coitum days 6

- 15. No mortality or significant differences in clinical signs, body weight development, or gross pathology between controls and treated groups were observed. No effects on development were noted. The maternal and developmental rat NOAELs were 3030 ppm. Rabbits (15/dose) were dosed on postinsemination days 7

- 19. High

- dose rabbit dams had a slightly lower body weight gain, particularly during the first phase of exposure. The maternal NOAEL for rabbits was 758 ppm. Fetuses exhibited n o signs of developmental3

changes in response to isobutanol. Therefore, the rabbit developmental NOAEL was 3030 ppm, the highest dose.

In a 2

- generation reproductive inhalation study isobutanol (99.9%) was

administered to 30 Crl:CD(SD)IGS BR rats/sex/dose by whole body exposure at 0, 500,1000 and 2500 ppm (0,1476, 2952, and 7380 mg/m^) for 6 hours per day 7 days per week. Exposure began at the commencement of the study for the F 0 generation, and on postnatal day 28 for the F1 generation. It ended after wea ning of the pups (F 0 g eneration postnatal day 28, F1 generation postnatal day 21). For dams, exposure was discontinued after day 20 of gestation through lactation day 5. No exposure

- rel ated effects were

observed on F0 and F1 parental survival or on F 0 and F1 reproductive performance, body weights, food consumption and food efficiency in males or females. There were no significant spermatogenic or macroscopic findings, changes in primordial follicle or corpora lutea counts, changes in mean organ weights or h istopathologic lesions in the F 0 or F1 rats at any dose. Pup endpoints were not significant for either F1 or F2 generations, including survival, general physical condition, and mean body weights. There were no macroscopic findings, changes in mean organ we ights, or maturation of F1 pups. The

NOAEL of isobutanol for parental systemic, reproductive and neonatal toxicity is 2500 ppm (7380 mg/m 3 the maximum applied dose ) in males and females of the F0 , F1 and F2 generations. The study was rated "reliable withou t restriction" by the European Chemicals Agency (ECHA).

4. Subchronic toxicity. No repeat

- dose studies of methyl isobutyrate were

identified in a search of the toxicological literature. Methyl isobutyrate was categorized by JECFA i nto the same category a s isobutyl isobutyrate, for which a subchronic toxicity study exists . Isobutyl isobutyrate is similar in structure to methyl isobutyrate; both compounds contain an isobutyl ester group and are therefore expected to be similarly

metabolized.

In an 18

- wee k oral gavage study Wistar rats (15/sex/dose) received doses of 0,
10,100, or 1000 mg/kg bw/day. No lasting significant effects were no ted in blood or urine

parametes, histological examination, behavior, appearance, body weight, or food/water

consu mption. There were no significant changes in organ weights related to treatment of

animals with isobu tyl isobutyrate. The NOAEL was reported to be 1000 mg/kg/day.

The repeat

- dose toxicity of isobutanol was also considered in the evaluation of methyl isobutyrate . Methyl isobutyrate and isobutanol have long been consumed by

humans because both compounds are natural food chemicals as well as being food additives permitted for direct addition to food (21 CFR 172.515). This approach is further justified based on the structural similarity and metabolic relationship between the two compounds. Both have an oxy

- isobutane group, plus both compounds are metabolized in vivo to form isobutyric acid in a 1:1 molar ratio. Based on these structural and metabolic similarities, it seems reasonable to conclude that isobutanol could also approximate the toxicity of methyl isobutyrate.

In a 90

- day oral rodent toxicity study on isobutanol, which served as the scientific

basis for US ERA' s oral Reference Dose (RfD) for that compound, isobu tanol was4

administered to 30 Crj: CD(SD) rats/sex/dose by gavage for 90 days at dose levels of 0,100, 316, or 1000 mg/kg bw/day. Treatment related effects were seen only at 1000 mg/kg bw/day, and included hypoactivity, which was significant during wee k one and decreased markedly after week 4, and lower body weight gain (18% below that of control rats) in males during week one. Food consumption averages were below those of the controls for both males and females during weeks 1 and 2. Clinical signs and effects on body weight and food consumption were all transient and were considered as adaptive and therefore as not adverse. In addition, serum potassium levels were 11

- 15% lower in both sexes compared to controls on day 29, but group mean serum potassium

concentrations were similar for treated and control groups at the final clinical pathologic

evaluation . No difference between dosed groups and controls were found for ophthalmoscopic examina tion

, hematology, urinalysis, organ weights, gross pathology

and h istopathology. The NOEL determined to be 316 mg/kg bw/day and the NOAEL was 1000 mg/kg/day. U.S. EPA derived an oral RfD of 0.3 mg/kg/day for isobutanol by applying uncertainty factors totaling 1000 to this NOEL.

Wistar rats (10/sex/group) were exposed t o isobutanol in drinking water at concentrations of 0, 1000, 4000, or 16,000 ppm, equivalent to approximately 0, 80, 340, or 1450 mg/kg bw/day isobutanol actually ingested. The highest dose was chosen based on palatability. The 90

- day study was carried out under OECD Test Guideline 408 and included full hematology, clinical chemistry, urinalysis, and ophthalmological endpoints as well as post

- sacrifice histological exam. Body weight, food and water consumption, and clinical signs of toxicity were monitored throughout the study. The following organs were weighed: livers, kidneys, adrenal glands, and testes. There were no significant dose

dependent signs of toxicity in any of these parameters. Study authors concluded that the NOAEL for isobutanol was the highe st dose, 1450 mg/kg/day

.

In a 90

- day inhalation study, 99% pure isobutanol was administered by dynamic whol e

body exposure to 10

- 20 Sprague

- Dawley rats/sex/dose at 0, 250, 1000, or 2500 ppm for 6 hours p er day, 5 days/week. During exposure time only, ther e was a slight decreased

response to e xternal stimuli that disappeared immediately after exposure. ECHA

considered it an effect of the narcotic properties of isobutanol rather than an adverse effect. In high dose females, t ota l erythrocyte count, hemoglobi n, and hematocrit were slightly elevated compared to controls (p < 0.05). ECHA considered this to be not biologically significant. No differences were found in body weight, food consumption, ophthalmoscopic examination, clinical observation, clinical chemi stry, neurobehavioral observations, organ weights, gross pathology, and histopathology. The NOAEL for

repeat

- dose effects including neurotoxicity is 2500 ppm.

5. Chronic toxicity. There were no adequate studies on the carcinogenic potential

of methyl iso butyrate or isobutanol. Methyl isobutyrate was not genotoxic in one study

and it does not contain reactive substructures of concern

.

6. Animal metabolism. Metabolism of aliphatic esters such as methyl isobutyrate proceeds rapidly through hydrolysis to fo rm an alcohol and carboxylic acid. These are

r eactions of the carboxylesterases or esterases, which predominate in hepatocytes but are present in most tissues throughout the body, including small intestine, colon, kidney,5

trachea and lung. Hydrolysis of me thyl isobutyrate is extensive and will form methanol and isobutyric acid. Isobutyric acid is metabolized to propionic acid which, in turn, is

converted to succinic acid and ultimately to glucose and glycogen. Methanol is oxidized and excreted ultimately as CO 2 and water.

7. Metabolite toxicology

. NA

8. Endocrine disruption

. Toxicity data related to endocrine disruption were not

identified in the methyl isobutyrate database. As the scientific knowledge develops, screening of additional compounds may be a dded to the Endocrine Disruptor Screening Program (EDSP). When additional screening and/or testing is conducted, methyl isobutyrate may be the focus of screening and/or testing to better characterize effects related to endocrine disruption.

C. Aggregate E xposure

1. Dietary exposure. The estimated dietary exposure to methyl isobutyrate was determined using methods to estimate chronic dietary exposure for a generic inert ingredient. This assessment considers drinking water and crop

- specific residues from p re

harvest applications of agricultural insecticides, herbicides and fungicides, assuming the highest established tolerance level residue for each commodity. The assessment assumes

that the ingredient is used on all crops. The inert ingredient is assumed t o be present in all

commo dities treated with 57 of the most significant active ingredients at the maximum

tolerance level a s identified by the U.S. EPA for the default assessment. Chronic dietary exposure estimates we r e derived for the general US populatio n and sub

- groups of the population using the Dietary Exposure Evaluation Model, DEEMTM. The inert ingredient

is assumed to be in the formulati on at a concentration of 50% for the default assessment. Chronic dietary exposure estimates wer e derived for the ge neral US population and subgroups of the population. The estimated exp osure for the total US population is 0.1893 mg/kg bw/day, or 1.89% of the cPAD. Children age 1 to 2 years old have the highest estimated exposure at 0.7062 mg/kg bw/day, or 7.06% of the cPAD.

i. Food. Dietary exposures of concern are not anticipated for methyl isobutyrate

due to its lack of persis tence in the environment and lo w general toxicity. A significant

source of dietary methyl isobutyrate comes from natural food sources and its use as a food additive. Methyl isobutyrate occurs naturally in a wide variety of foods, including apple juice, bananas, blueberry, dill herb, grape, kiwi fruit, kumquat peel oil, melon, naranjilla fruit, papaya, pineapple, potato fried potato, starfruit, a nd strawberry juice. JECFA (1999) estimated the current level of intake of methyl isobutyrate as a flavoring agent to be 270 u g/day in the U.S., equivalent to approximately 0.00386 mg/kg bw/day

for a 70

- kg person.

ii. Drinking water

. Methyl isobutyrate e xposure via drinking water from use as an

inert ingredient is not expected to be significant. The physical and chemical properties of methyl isobutyrate indicate it is moderately volatile, readily biodegradable, and therefore not persistent in water. Expos ure via the drinking water was estimated in the DEEM dietary exposure assessment assuming a concentration of 100 ppb.6

2. Non

- dietary exposure

. Residential exposures of concern are not anticipated for methyl isobutyrate due to its inherent ability to biod egrade in the environment, low projected use

- level in pesticides, and low general toxicity.

D. Cumulative Effects

Section 408(b)(2)(D) (9v) of the FFDCA requires that, when considering whether

to establish, modify, or revoke a tolerance, the Agency cons ider "available information" concerning the cumulative effects of a particular pesticide's residues and "other

substances that have a common mechanism of toxicity."

To our knowledge there are no available data or other reliable information that

suggests any toxic effects produced by methyl isobutyrate would be cumulative with those of any other chemical compounds. EPA has not made a common mechanism of toxicity finding as to m ethyl isobutyrate and other compounds. Isobutyl isobutyrate does not produce tox ic metabolites in common with other substances of potential concern. For the purpose of the tolerance exemption proposed, it is assumed that methyl isobutyrate

does not share a common mechanism of toxicity with other substances.

E. Safety Determination

1. U.S. population. Taking into consideration all available information on methyl isobutyrate, there is a reasonable certainty that no harm to any population subgroup will

result from dietary and other non

- occupational exposures to methyl isobutyrate when

used as an inert ingredient in an inert mixture intended for use in pesticide formulations. The toxicity profile of methyl isobutyrate indicates a low hazard from all routes of exposure, and a lack of genotoxicity. The NOAEL of 1000 mg/kg/day derived for

i sobutyl isobutyrate was used as a point of departure for methyl isobutyrate. Uncertainty

factors often each for intra

- and interspecies extrapolations were used, totaling l 00 x. An RfD was then established for methyl isobutyrate of 10 mg/kg/day. The chronic Population Adjusted Dose (cPAD) was determined to be the same as the RfD because no effects of isobutanol on development or reproduction were observed and therefore there was insufficient evidence for increased susceptibility of sensitive populations. The refore, the oral RfD and cPAD for methyl isobutyrate are both 10 mg/kg/day. For the total US population, the estimated chronic dietary exposure from food and drinking water for methyl isobutyrate, calculated as 50% of all agricultural formulations, is 1.89 % of the

cPAD. This estimated exposure to methyl isobutyrate is well below any level of potential

concern.

2. Infants and children

. There is a reasonable certainty that no harm to infants and children will result from the use of methyl isobutyrate as an inert ingredient in pesticide products. There is no indication that this chemical is a developmental toxin or that there

is a concern for increased sensitivity to infants and children to methyl isobutyrate when

used as an inert ingredient in pesticide form ulations. For this reason, a safety factor7

analysis has not been implemented to assess risk and the additional tenfold safety factor for the protection of infants and children is also unnecessary.

F. International Tolerances

NA