97-3646. ISK Biosciences Corporation; Pesticide Tolerance Petition Filing  

  • [Federal Register Volume 62, Number 30 (Thursday, February 13, 1997)]
    [Notices]
    [Pages 6780-6784]
    From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
    [FR Doc No: 97-3646]
    
    
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    ENVIRONMENTAL PROTECTION AGENCY
    [PF-708; FRL-5587-3]
    
    
    ISK Biosciences Corporation; Pesticide Tolerance Petition Filing
    
    AGENCY: Environmental Protection Agency (EPA).
    
    ACTION: Notice of filing.
    
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    SUMMARY: This notice announces the filing of a pesticide petition 
    proposing the establishment of a regulation for residues of 
    chlorothalonil in or on almonds and almond hulls. The notice includes a 
    summary of the petition prepared by the petitioner, ISK Biosciences 
    Corporation.
    
    DATES: Comments, identified by the docket number [PF-708], must be 
    received on or before March 17, 1997.
    
    ADDRESSES: By mail, submit written comments to: Public Response and 
    Program Resources Branch, Field Operations Division (7506C), Office of 
    Pesticide Programs, Environmental Protection Agency, 401 M St., SW., 
    Washington, DC 20460. In person, bring comments to Rm. 1132, CM #2, 
    1921 Jefferson Davis Highway, Arlington, VA.
        Comments and data may also be submitted electronically by sending 
    electronic mail (e-mail) to: opp-docket@epamail.epa.gov. Comments and 
    data will also be accepted on disks in WordPerfect 5.1 file format or 
    ASCII file format. All comments and data in electronic form must be 
    identified by docket number [PF-708]. Electronic comments on this 
    notice of filing may be filed online at many Federal Depository 
    Libraries. Additional information on electronic submissions can be 
    found in Unit II. of this document.
        Information submitted as comments concerning this document may be 
    claimed confidential by marking any part or all of that information as 
    ``Confidential Business Information'' (CBI). CBI should not be 
    submitted through e-mail. Information marked as CBI will not be 
    disclosed except in accordance with procedures set forth in 40 CFR part 
    2. A copy of the comment that does not contain CBI must be submitted 
    for inclusion in the public record. Information not marked confidential 
    may be disclosed publicly by EPA without prior notice. All written 
    comments will be available for public inspection in Rm. 1132 at the 
    address given above, from 8:30 a.m. to 4 p.m., Monday through Friday, 
    excluding legal holidays.
    
    FOR FURTHER INFORMATION CONTACT: By mail: Cynthia Giles-Parker, Product 
    Manager (PM 22), Registration Division (7505C), Office of Pesticide 
    Programs, Environmental Protection Agency, 401 M St., SW., Washington, 
    DC 20460. Office location, telephone number, and e-mail address: 
    Crystal Mall #2, Room 229, 1921 Jefferson Davis Highway, Arlington, VA, 
    703-305-7740, e-mail: giles-parker.cynthia@epamail.epa.gov.
    
    SUPPLEMENTARY INFORMATION: EPA has received a pesticide petition (PP 
    5F4558), originally published in the Federal Register on November 15, 
    1995 (60 FR 57419) (FRL-4971-5), from ISK Biosciences Corporation 
    (``ISK''), 5966 Heisley Road, P.O. Box 8000, Mentor, Ohio 44061, 
    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 180.275 by 
    establishing tolerances for residues of the fungicide chlorothalonil 
    and its metabolite, 4-hydroxy-2,5,6-trichloroisophthalonitrile (SDS-
    3701) in or on the raw agricultural commodity (RAC) almonds (nutmeats) 
    at 0.05 parts per million (ppm) and almond hulls at 1.0 ppm. The 
    proposed analytical method is by electron capture gas chromatography. 
    EPA has determined that the petition contains data or information 
    regarding the elements set forth in section 408 (d)(2) of the FFDCA; 
    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.
        As required by section 408(d) of the FFDCA, as recently amended by 
    the Food Quality Protection Act (FQPA) Pub. L. 104-170, ISK included in 
    the petition a summary of the petition and authorization for the 
    summary to be published in the Federal Register in a notice of receipt 
    of the petition. The summary represents the views of ISK. EPA is in the 
    process of evaluating the petition. As required by section 408(d)(3) of 
    the FFDCA, EPA is including the summary as a part of this notice of 
    filing. EPA has made minor edits to the summary for the purpose of 
    clarity.
    
    I. Petition Summary
    
    A. Residue Chemistry Data
    
        1. Plant/animal metabolism. The nature of the residue of 
    chlorothalonil in plants and animals, including ruminants, is well 
    understood. Chlorothalonil is not systemic in plants. Any 
    chlorothalonil residue found on almond nutmeats occurs as a surface 
    residue from transfer of the residue during harvesting and shelling 
    operations. Chlorothalonil is rapidly metabolized in the ruminant and 
    is not transferred to meat and milk from the dietary consumption by 
    animals. Furthermore, chlorothalonil is not stable in meat or milk.
        2. Analytical method. An adequate analytical method (gas 
    chromatography) is available for enforcement purposes. The method is 
    listed in the Pesticide Analytical Manual, Vol. II (PAM II).
        3. Magnitude of the residues. Residue data from studies conducted 
    with almonds support a tolerance of 0.05 ppm for combined residues of 
    chlorothalonil and its metabolite, 4-hydroxy-2,5,6-
    trichloroisophthalonitrile in/on almond nutmeats and 1.0 ppm in/on 
    almond hulls. Residues of chlorothalonil on plants are surface 
    residues. Nutmeats are not systemically exposed to chlorothalonil since 
    chlorothalonil is not a systemic fungicide in plants. Chlorothalonil 
    residues are not directly translocated to the nutmeats, but residues 
    from the hulls that contaminate the almond shells during harvest may be 
    transferred to the nutmeats during the shelling process.
    
    B. Toxicological Profile
    
        The following studies on file with the Agency support this 
    petition.
        1. Acute toxicity. Acute toxicity studies include an acute oral rat 
    study on technical chlorothalonil with an LD50 >10,000 milligram/
    kilogram (mg/kg), an acute dermal toxicity study in the rabbit with an 
    LD50 >20,000 mg/kg, a 4-hour inhalation study with finely ground 
    technical chlorothalonil resulting in a LC50 of 0.092 mg/L (actual 
    airborne concentration), a primary eye irritation study with 
    irreversible eye effects in the rabbit at 21 days, a primary dermal 
    irritation study showing technical chlorothalonil is not a dermal 
    irritant, and a dermal sensitization study showing technical 
    chlorothalonil is not a skin sensitizer.
        2. Genotoxicity. The mutagenic potential of chlorothalonil has been 
    evaluated in a large number of studies covering a variety of endpoints. 
    ISK concludes that chlorothalonil is not mutagenic.
        Mutagenicity studies with chlorothalonil include gene mutation 
    assays in bacterial and mammalian cells; in vitro and in vivo 
    chromosomal aberration assays; DNA repair assays in bacterial systems; 
    and cell
    
    [[Page 6781]]
    
    transformation assays. All were negative with the following two 
    exceptions:
        i. Chlorothalonil was positive in an in vitro chromosomal 
    aberration assay in CHO cells without metabolic activation but was 
    negative with metabolic activation.
        ii. In vivo chromosomal aberration studies in rats and mice were 
    negative and one study in the Chinese hamster was equivocal. The 
    results of this study could not be confirmed in a subsequent study at 
    higher doses. The conclusion was that chlorothalonil does not cause 
    chromosome aberrations in bone marrow cells of the Chinese hamster. It 
    can be concluded that chlorothalonil does not have clastogenic 
    potential in intact mammalian systems.
        In bacterial DNA repair tests chlorothalonil was negative in 
    Bascillus subtilis, but was positive in Salmonella typhimurium. In an 
    in vivo DNA binding study in rats, with 14C-chlorothalonil, there 
    was no covalent binding of the radiolabel to the DNA of the kidney, 
    which is the target organ for chlorothalonil toxicity in rodents.
        3. Developmental and reproductive toxicity. A developmental 
    toxicity study with rats given gavage doses of 0, 25, 100, and 400 mg/
    kg body weight (bwt)/day from days 6 through 15 of gestation resulted 
    in a no observed effect level (NOEL) for maternal toxicity of 100 mg/
    kg/day based on increased mortality, reduced body weight, and a slight 
    increase in early resorptions at the highest dose. There were no 
    developmental effects observed at any dose in this study.
        A developmental toxicity study in rabbits given gavage doses of 0, 
    5, 10, or 20 mg/kg/day on days 7 through 19 of gestation resulted in a 
    maternal NOEL of 10 mg/kg/day. Effects observed in the dams in the 
    high-dose group were decreased body weight gain and reduced food 
    consumption. There were no developmental effects observed in this 
    study.
        A 2-generation reproduction study in rats fed diets containing 0, 
    500, 1,500 and 3,000 ppm resulted in a reproductive NOEL of 1,500 ppm 
    (equivalent to 115 mg/kg/day) based on lower neonatal body weights by 
    day 21. There were no effects seen on any other reproductive parameter 
    at any dose level in this study.
        4. Subchronic toxicity. i. A 90-day subchronic toxicity study was 
    conducted in rats at doses of 0, 1.5, 3.0, 10, and 40 mg/kg bwt. 
    Treatment related hyperplasia and hyperkeratosis of the forestomach was 
    observed at the two highest dose levels. Although the initial 
    histopathological evaluation did not demonstrate any nephrotoxicity, a 
    subsequent evaluation observed a treatment-related increase in 
    hyperplasia of the proximal tubule epithelium at 40 mg/kg bwt in the 
    male rats but not in the females. The NOEL for renal histopathology was 
    10 mg/kg bwt in males and 40 mg/kg bwt in females.
        ii. A 90-day oral toxicity study was conducted in dogs with dose 
    levels of technical chlorothalonil of 15, 150, and 750 mg/kg bwt/day. 
    The two highest dosages resulted in lower body weight gain in male 
    dogs. The NOEL was 15 mg/kg/day. There were no macroscopic or 
    microscopic tissue alterations related to chlorothalonil and there were 
    no signs of renal toxicity.
        iii. Two 21-day dermal toxicity studies have been conducted with 
    technical chlorothalonil. In the initial study, doses of 50, 2.5, and 
    0.1 mg/kg bwt/day were administered to rabbits. The NOEL for systemic 
    effects was greater than 50 mg/kg bwt/day and the NOEL for dermal 
    irritation was 0.1 mg/kg bwt/day.
        A subsequent 21-day dermal study was conducted in male rats to 
    specifically evaluate the potential for nephrotoxicity in this 
    laboratory species following dermal dosing. In this study the doses 
    were 60, 100, 250, and 600 mg/kg bwt/day. The NOEL for nephrotoxicity 
    was greater than 600 mg/kg bwt/day.
        5. Estrogenic effects. Based upon all of the chronic toxicity, 
    teratogenicity, mutagenicity, and reproductive studies conducted with 
    chlorothalonil and its metabolites, ISK concludes that there were no 
    results which indicate any potential to cause estrogenic effects or 
    endocrine disruption. These effects would have manifested themselves in 
    these studies as reproductive or teratogenic effects or by producing 
    histopathological changes in estrogen sensitive tissues such as the 
    uterus, mammary glands, or the testes. Thus, ISK concludes based upon 
    the in vivo studies, that chlorothalonil does not cause estrogenic 
    effects.
        6. Chronic toxicity. i. A 12-month chronic oral toxicity study in 
    Beagle dogs was conducted with technical chlorothalonil at dose levels 
    of 15, 150, and 500 mg/kg/day. The NOEL was 150 mg/kg/day based on 
    lower blood albumin levels at the highest dose. There was no 
    nephrotoxicity observed at any dose in this study. This study replaced 
    an old outdated study that was not conducted under current guidelines 
    and did not use the current technical material.
        ii. A chronic feeding/carcinogenicity study with Fischer 344 rats 
    fed diets containing 0, 800, 1,600 or 3,500 ppm (equivalent to 0, 40, 
    80 or 175 mg/kg bwt/day) for 116 weeks in males or 129 weeks in 
    females, resulted in a statistically higher incidence of combined renal 
    adenomas and carcinomas. At the high dose, which was above the MTD, 
    there was also a statistically significant higher incidence of tumors 
    of the forestomach in female rats.
        iii. In a second chronic feeding/carcinogenicity study with Fischer 
    344 rats, designed to define the NOEL for tumors and the preneoplastic 
    hyperplasia, animals were fed diets containing 0, 2, 4, 15 or 175 mg/
    kg/day. The NOEL in this study, based on renal tubular hyperplasia, was 
    a nominal dose of 2 mg/kg bwt/day. Because of the potential for 
    chlorothalonil to bind to diet the 2 mg/kg bwt/day dose, expressed as 
    unbound chlorothalonil, is 1.8 mg/kg bwt/day. The NOEL for hyperplasia 
    and hyperkeratosis of the forestomach was 4 mg/kg bwt/day or a dose of 
    3.8 mg/kg bwt/day based on unbound chlorothalonil.
        iv. A 2-year carcinogenicity study, conducted in CD-1 mice at 
    dietary levels of 0, 750, and 1,500 or 3,000 ppm (equivalent to 0, 107, 
    214 or 428 mg/kg/day), resulted in a statistically higher incidence of 
    squamous cell carcinomas of the forestomach in both sexes and a 
    statistically higher incidence of combined renal adenomas/carcinomas in 
    only the male mice receiving the low dose. There were no renal tumors 
    in any female mouse in this study.
        v. A 2-year carcinogenicity study, in male CD-1 mice for the 
    purpose of establishing the NOEL for renal and forestomach effects, was 
    conducted at dietary levels of 0, 10/15, 40, 175, or 750 ppm 
    (equivalent to 0, 1.4/2.1, 5.7, 25 or 107 mg/kg/day). The NOEL for 
    renal effects was 40 ppm and the NOEL for forestomach effects was 15 
    ppm. This study did not duplicate the results from the previous study 
    where a statistically higher incidence of renal tumors, when compared 
    to controls, was observed at 750 ppm.
        In 1987, the Office of Pesticide Programs' Toxicology Branch Peer 
    Review Committee classified chlorothalonil as a B2 (probable human 
    carcinogen) based on evidence of carcinogenicity in the forestomach and 
    kidneys of rats and mice. The Agency currently regulates chlorothalonil 
    as a B2 carcinogen although ISK has provided a significant amount of 
    mechanistic data indicating that the tumors result from a threshold 
    mechanism. A potency factor, Q1* (Q1
    
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    star), of 0.00766 (mg/kg/day)1 has been used by the Agency when 
    conducting mathematical modeling to estimate carcinogenic risk to man. 
    ISK believes that because the nephrotoxicity seen in the rat is due to 
    a threshold mechanism, any risk associated with chlorothalonil can be 
    managed using the margin of safety (exposure) approach.
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        1``Mechanistic Interpretation of the Oncogenicity of 
    Chlorothalonil in Rodents and an Assessment of Human Relevance,'' by 
    Drs. C. F. Wilkinson and J. C. Killeen, Regulatory Toxicology and 
    Pharmacology 24: 69-84 (1996), Article No. 006.
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        Numerous metabolism and toxicology studies indicate that 
    chlorothalonil is non-genotoxic and produces a species-specific renal 
    toxicity in the rat that eventually may lead to tumor formation through 
    an epigenetic mechanism. Studies comparing metabolism and toxicological 
    effects in dogs with those in rats demonstrate that the renal effects 
    observed in the rat are due to the exposure of the kidney of the rat to 
    significant levels of nephrotoxic thiol metabolites of chlorothalonil. 
    In the dog, no thio metabolites are found and there are no toxic 
    effects seen in kidneys of dogs dosed with high levels of 
    chlorothalonil.
        7. Reference dose (RfD). The NOEL for chlorothalonil in the rat is 
    1.8 mg/kg bwt based on the nephrotoxicity observed in the chronic rat 
    study. The NOEL in the dog was 15 mg/kg bwt in the 90-day study and 150 
    mg/kg bwt based on the 1-year study. NOEL for maternal toxicity from 
    developmental studies are 10 mg/kg bwt in rabbits and 100 mg/kg bwt in 
    the rat. The NOEL for pup growth in the reproduction study was 1,500 
    mg/kg bwt, which would be most conservatively estimated as equating to 
    approximately 75 mg/kg bwt. Data indicate that the nephrotoxicity in 
    the rat is produced through a mechanism for which there is a clear 
    threshold. In a study which measured cell turnover in the rat kidney 
    with proliferating cell nuclear antigen (PCNA) immunohistochemical 
    staining, a NOEL was established at 1.5 mg/kg bwt. Other chronic 
    studies have established the NOEL for hyperplasia in the kidney to be 
    1.8 mg/kg bwt. If all the available toxicity data in laboratory animals 
    are considered without regards to its applicability to humans, the 
    lowest NOEL for any adverse effect would be 1.5 mg/kg bwt/day. Because 
    the mechanism of toxicity which is related to the tumor formation in 
    the kidney has been shown to have a threshold, the use of the normal 
    100-fold safety factor in conjunction with the 1.5 mg/kg NOEL would 
    produce a reference dose which would provide more than adequate safety 
    for all of the possible effects seen in any laboratory animal.
        In two recent reviews of chlorothalonil by the Joint Meeting of 
    Pesticide Residue Experts (1990 and 1992) and the review by the World 
    Health Organization's International Program for Chemical Safety, these 
    esteemed groups concluded that the rat was not the appropriate species 
    to use in consideration of the risk assessment for man. They concluded 
    that the dog was the more appropriate species for determination of 
    subchronic and chronic effects. If the toxicological data for the dog 
    were used, the NOEL would be at least 15 mg/kg bwt, which is based on 
    the most recent 90-day study of the dog.
        Therefore, under the most conservative scenario (using the 
    toxicological data in the rat), the reference dose would be 1.8 mg/kg 
    bwt/day divided by a 100-fold safety factor or 0.018 mg/kg bwt/day with 
    a threshold model being used for carcinogenic risk assessment. In the 
    scenario that uses the toxicological data of the dog, the reference 
    dose would be 15 mg/kg bwt/day divided by a safety factor of 100 or 
    0.15 mg/kg bwt/day.
    
    C. Aggregate Exposure
    
        The following is a description of the likelihood of exposure to 
    chlorothalonil from various routes.
        1. Dietary exposure.-- i. Food. The Agency's Dietary Exposure 
    Analysis dated April 1, 1996, of ISK's petition (PP 5F4558), which 
    requested tolerances for chlorothalonil and its metabolite, 4-hydroxy- 
    2,5,6-trichloroisophthalonitrile (SDS-3701) in/on almond nutmeats and 
    almond hulls, determined the dietary exposure from the proposed new 
    anticipated residue contributed from almonds to be 0.000001 mg/kg bwt/
    day to the U.S. population and also to children ages 1 to 6.
        The Agency had calculated that the exposure of the general 
    population from existing published tolerances for chlorothalonil is 
    0.000133 mg/kg bwt/day and 0.00021 mg/kg bwt/day for infants and 
    children ages 1 to 6. Unfortunately, the Agency's calculation of the 
    total exposure contained a significant error. The Agency grossly 
    overestimated the exposure from the use of chlorothalonil on mushrooms 
    by using an anticipated residue of 2.54 ppm which constitutes an 
    illegal residue. The tolerance is 1.0 ppm. There were also other 
    overestimates of less magnitude in the April 1996 EPA document. ISK 
    believes that the correct exposure, based on the current registered 
    uses for chlorothalonil, is 0.0000642 mg/kg bwt/day for the general 
    population and 0.000105 mg/kg bwt/day for infants and children 1 to 6 
    years of age.
        ii. Drinking water. Chlorothalonil was included for monitoring in 
    the National Survey of Pesticides in Drinking Water Wells conducted by 
    EPA. No chlorothalonil residues were detected in any of the 1,300 
    community water systems and domestic wells (using methodology for 
    chlorothalonil having a limit of detection (LOD) of 0.06 g/l 
    and limit of quantitation of 0.12 g/l). The absence of 
    chlorothalonil detections in the National Survey of Pesticides in 
    Drinking Water Wells provides adequate information to conclude that 
    chlorothalonil is not a contaminant in drinking water wells and that 
    the population is not exposed to chlorothalonil in these water sources. 
    These findings are consistent with the known physical/chemical 
    properties of chlorothalonil including low water solubility (0.9 ppm) 
    and high affinity for organic matter including soil. It has also been 
    demonstrated that chlorothalonil does not leach into groundwater from 
    applications made to growing crops.
        Aerobic aquatic metabolism studies with chlorothalonil establish a 
    half-life in natural aquatic habitats of less than 10 hours, depending 
    on environmental conditions. Considering the short half-life of 
    chlorothalonil in natural water/sediment systems and that surface water 
    is filtered and treated prior to consumption, chlorothalonil is not 
    likely to be present in drinking water obtained from natural surface 
    water systems.
        An exposure estimate, based on surface water concentration recently 
    cited by EPA, would conclude that the average concentration in surface 
    water would be less than 0.002 ppm. Assuming that everyone in the 
    United States consumed untreated surface water, the exposure to 
    chlorothalonil of the general population would be less than 5.8  x  
    10-7 mg/kg bwt/day. This would be a worse case scenario, which 
    would greatly overestimate exposure.
        2. Non-dietary exposure. Potential non-dietary exposures to 
    chlorothalonil may result from the following uses of chlorothalonil. In 
    each case, the exposure would be from the dermal route and only for an 
    intermittent duration. The two 21-day dermal studies that have been 
    conducted in the rabbit and rat indicate that there is no 
    nephrotoxicity associated with the dermal exposure to chlorothalonil at 
    dose levels up to 600 mg/kg/day. Therefore, the exposures from the uses 
    of chlorothalonil listed below would not
    
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    be expected to add to the carcinogenic risk associated with 
    chlorothalonil.
        i. Golf course uses. Chlorothalonil products are commonly applied 
    to golf course trees and greens to control a broad complex of turf 
    diseases. Application to golf course fairways is much less common. Golf 
    is not a game played by infants or small children, therefore no 
    exposure to infants and children would be anticipated.
        ii. Residential owner uses. Applications of chlorothalonil products 
    to home lawns are rare. Thus, there is very little exposure to 
    chlorothalonil related to use on residential turf. Applications to 
    roses and other ornamentals in home gardens is also a minor use of 
    chlorothalonil.
        iii. Paint. Chlorothalonil is used in paints and stains for control 
    of mildew and molds on exterior surfaces of buildings. Chlorothalonil 
    is also occasionally used for interior paints, but this use represents 
    only a small proportion of the chlorothalonil used in paints. About 2% 
    of the chlorothalonil used in paint is used in interior paint; however, 
    only 0.2% or less of interior paints in the United States contain 
    chlorothalonil. In paints chlorothalonil is tightly bound within the 
    paint matrices; thus, effective control of mildew may last for several 
    years and the potential for exposure is very limited.
        iv. Grouts. Chlorothalonil is used in cement tile grouts and for 
    control of mildew and molds. Chlorothalonil is bound within the grout 
    matrices and very little is available for exposure. This is a minor use 
    of chlorothalonil and non-occupational dermal exposure of humans to 
    chlorothalonil from this source is extremely low.
        v. Wood treatment. Chlorothalonil is not currently used for 
    pressure-treating wood. It is used for control of sapstain as a surface 
    treatment on rough-cut, newly-sawn lumber to protect it from molds and 
    mildews while drying. Being a surface residue, it is removed during the 
    finishing operations prior to sale of the wood. Chlorothalonil does not 
    occur in structural wood used for residential or occupational 
    scenarios.
    
    D. Cumulative Effects
    
        ISK has considered the potential for cumulative effects of 
    chlorothalonil and other substances that have a common mechanism of 
    toxicity. Chlorothalonil is a halogenated benzonitrile which readily 
    undergoes displacement of the 2, 4 and 6 chlorines by glutathione and 
    other thiol containing amino acids and proteins. In the rat, the thiol 
    metabolites are sufficiently absorbed to produce a nephrotoxic effect. 
    In dogs where this absorption does not occur, nephrotoxicity does not 
    occur. ISK does not have any information to indicate that toxic effects 
    observed in rats occur through a mechanism which is common to any other 
    agricultural chemical. Thus, consideration of common mechanisms of 
    toxicity is not appropriate at this time.
        Chlorothalonil should not be confused with chlorinated hydrocarbon 
    pesticides which have significantly different chemical and biological 
    properties.
    
    E. Safety Determination
    
        1. U.S. population. In EPA's Dietary Exposure Analysis, dated April 
    1, 1996, for chlorothalonil and its metabolite in/on almond nutmeats 
    and almond hulls, the Agency determined that the oncogenic dietary 
    risks associated with potential exposure from anticipated residue of 
    0.05 ppm from almonds is minimal. The risk assessment concluded that 
    chlorothalonil does not pose a significant chronic or acute dietary 
    risk for uses that are currently published or for uses recommended by 
    EPA for registration. Unfortunately, the Agency's calculation of the 
    total exposure for existing published uses contained a significant 
    error. The Agency grossly overestimated the exposure from the use of 
    chlorothalonil on mushrooms by using an anticipated residue of 2.54 ppm 
    which constitutes an illegal residue. The tolerance is 1.0 ppm.
        The Agency has used a linearized model to estimate the carcinogenic 
    risk associated with chlorothalonil, whereas ISK believes that a 
    threshold based model is appropriate. If the linearized multistage 
    model is used with the corrected exposure estimates for food presented 
    earlier, the carcinogenic risk would be estimated at 4.9  x  107 
    for the general population and 8.0  x  107 for infants and 
    children. Using the overestimated exposure estimates of EPA, with a 
    threshold based model and using the conservative RfD of 0.018 mg/kg 
    bwt/day, the margin of safety for the general population would exceed 
    10,000 and the margin of safety for infants and children would exceed 
    7,000. Using corrected exposure estimates would obviously yield larger 
    margins of exposure. Using a conservative RfD of 0.018 mg/kg/day, as 
    the Agency has done in recent Dietary Risk Evaluation System (DRES) 
    analyses, and incorporating corrections needed in exposure values for 
    mushrooms and several other lesser corrections, ISK calculated the 
    overall dietary exposure to anticipated residues of chlorothalonil, 
    from all registered uses and pending uses of chlorothalonil, to be 
    0.36% of the RfD for the general U.S. population and 0.59% of the RfD 
    for children ages 1 to 6 years old, which is the group with the highest 
    exposure.
        Because the worse case assumption for human exposure from drinking 
    water indicates that exposure would be only 1% of the dietary exposure, 
    the risk assessment is not significantly altered by considering the 
    exposure from drinking water.
        2. Infants and children. There is a complete data base for 
    chlorothalonil which includes pre- and post-natal developmental 
    toxicity data as well as mechanistic data related to the rodent 
    specific nephrotoxicity observed in subchronic and chronic studies. The 
    toxicological effects of chlorothalonil in rodents are well understood. 
    Chlorothalonil has a low level of toxicity in dogs.
        In a 2-generation reproduction study in rats, all reproductive 
    parameters investigated showed no treatment-related effects except pup 
    weight gain. Specifically, the weights of pups exposed to 
    chlorothalonil were comparable to controls at parturition through day 
    four of lactation. It was only after day four of lactation, when the 
    pups begin to consume the test diet, that body weight gain lags behind 
    controls. This only occurred at the highest dose tested, which is 3,000 
    ppm. The dose of chlorothalonil the pups would receive would be far in 
    excess of the estimated adult dose of 150 mg/kg bwt/day (3,000 ppm 
    -20). The doses for the pups could have easily exceeded 500 mg/kg 
    bwt/day. Dose levels of 375 mg/kg bwt and above have been shown to 
    significantly affect body weight in the rat. Therefore, the reduction 
    of body weight gain observed in the reproduction study is considered to 
    be comparable to the effects that have been observed in older rats. The 
    NOEL for this effect was 1,500 ppm.
        In developmental toxicity studies conducted in the rat and the 
    rabbit, chlorothalonil did not cause any developmental effects even at 
    dose levels that produced significant maternal toxicity. In the rabbit 
    a dose level of 20 mg/kg bwt caused maternal toxicity, but there were 
    no developmental effects and in the rat, a dose level of 400 mg/kg bwt 
    caused maternal toxicity without developmental toxicity.
        The extensive data base that is available for chlorothalonil is 
    devoid of any indication that chlorothalonil would represent any 
    unusual or disproportionate hazard to infants or children. Therefore, 
    there is no need to impose an additional 10x safety factor
    
    [[Page 6784]]
    
    for infants or children. The standard uncertainty factor of 100x should 
    be used for all segments of the human population when calculating risks 
    associated with chlorothalonil.
    
    F. International Tolerances
    
        A maximum residue level has not been set for chlorothalonil on 
    almonds by the Codex Alimentarius Commission.
    
    II. Public Record
    
        EPA invites interested persons to submit comments on this notice of 
    filing. Comments must bear a notation indicating the docket number [PF-
    708].
        A record has been established for this notice of filing under 
    docket number [PF-708] including comments and data submitted 
    electronically as described below. A public version of this record, 
    including printed paper versions of electronic comments, which does not 
    include any information claimed as CBI, is available for inspection 
    from 8:30 a.m. to 4 p.m., Monday through Friday, excluding legal 
    holidays. The public record is located in Room 1132 of the Public 
    Response and Program Resources Branch, Field Operations Division 
    (7506C), Office of Pesticide Programs, Environmental Protection Agency, 
    Crystal Mall #2, 1921 Jefferson Davis Highway, Arlington, VA.
        Electronic comments can be sent directly to EPA at:
        opp-docket@epamail.epa.gov
    
    
        Electronic comments must be submitted as ASCII file avoiding the 
    use of special characters and any form of encryption.
        The official record for this notice of filing, as well as the 
    public version, as described above will be kept in paper form. 
    Accordingly, EPA will transfer all comments received electronically 
    into printed paper form as they are received and will place the paper 
    copies in the official record which will also include all comments 
    submitted directly in writing. The official record is the paper record 
    maintained at the address in ``ADDRESSES'' at the beginning of this 
    document.
    
    List of Subjects
    
        Environmental protection, Administrative practice and procedure, 
    Agricultural commodities, Pesticides and pests, Reporting and 
    recordkeeping requirements.
    
        Dated: February 7, 1997.
    
    Donald R. Stubb,
    
    Acting Director, Registration Division, Office of Pesticide Programs.
    
    [FR Doc. 97-3646 Filed 2-12-97; 8:45 am]
    BILLING CODE 6560-50-F
    
    
    

Document Information

Published:
02/13/1997
Department:
Environmental Protection Agency
Entry Type:
Notice
Action:
Notice of filing.
Document Number:
97-3646
Dates:
Comments, identified by the docket number [PF-708], must be received on or before March 17, 1997.
Pages:
6780-6784 (5 pages)
Docket Numbers:
PF-708, FRL-5587-3
PDF File:
97-3646.pdf