United States Office of Pesticides and Toxic Substances Environmental Protection Office of Pesticide Programs (TS-766C) Agency Washington, DC 20460 vvEPA Pesticide Fact Sheet Name of Chemical: METHOXYCHLOR Reason for Issuance: REGISTRATION STANDARD Date ISSUed: December 1988 Fact Sheet Number: is? 1. DESCRIPTION OF CHEMICAL Generic name: 1,1,l-trichloro-2,2-bis(4- methoxyphenyl) ethane Common name: Methoxychlor Trade Names: Marlate, Prentox, and Methoxcide Other Chemical Nomenclature: 1,1,l-trichloro-2,2-di(4- methoxyphenyl)ethane; 1,1- (2,2,2-tri chloroethylidene)- bis[4-methoxybenzene]; 1,1,1- trichloro-2,2-bis(p- methoxyphenyl)ethane; 2,2- b i s)p-methoxypheny1) -1,1,1 - trichloroethane CAS Registry No.: 72-43-5 EPA Pesticide Chemical Code (Shaughnessy Number): 034001 Empirical Formula: C16H15C13°2 Molecular Weight: 345.7 Year of initial registration: 1948 Pesticide type: Insecticide/Acaricide Chemical family: Chlorinated Hydrocarbon U.S. Registrants: Chemical Formulators; Prentiss Drug & Chemical Co., J.R. Simplot Co.; Dynachem Industries; Clover Chemical Co.; Drexel Chemical Co.; Kincaid Enterprises; and Wesley Industries ------- Enterprises; and Wesley Industries 2. USE PATTERNS AND FORMULATIONS Registered Uses: TERRESTRIAL FOOD CROP use: (1) seed treatment only use on grains and various vegetables; (2) foliar application (including seed treatment) use on vegetables and fruits; and (3) foliar application only use on vegetables and fruits TERRESTRIAL NON-FOOD CROP use on grasses, ornamentals and trees GREENHOUSE FOOD CROP use on mushrooms DOMESTIC AND NON-DOMESTIC OUTDOOR use around dwellings and for garbage and sewer areas, general urban outdoor use AQUATIC FOOD use on cranberry AQUATIC NON-FOOD use for mosquito larvae control in aquatic sites, such as beaches, lakes, marshes and rivers FORESTRY use on forest trees INDOOR use on: (1) postharvest stored grain commodity and premise treatment; (2) direct animal treatment for dogs, cats, and farm animals; (3) agricultural premise use; (4) kennelst dug sleeping quarters and cat sleeping quarters; (5) indoor domestic dwellings for use on household contents such as human clothing (including woolens); (6) direct application to humans; (7) commercial and industrial use in food processing, storage transportation areas and equipment Pests Controlled: various nuisance species (some of public health significance) including cockroaches, mosquitoes, flies and chiggers; various arthropods attacking field crops, vegetables, fruits, ornamentals, stored grain, livestock and domestic pets Methods of Application: sprays, fogs, paints, ground and aerial equipment, animal dust-bags, dips, sprays and back-rubbers Formulations: Wettable powders, dusts, emulsifiable 2 ------- concentrates, flowable concentrates„ liquid soluble concentrates, granules, ready-to-use products (liquids) and pressurized liquids 3. SCIENCE FINDINGS Summary Science Statement With the-exception of one mutagenicity study, there are n; acceptable acute, subchronic, or long-term toxicology/oncogenicity studies available to support technical methoxychlor. In the acceptable mutagenicity study, an unscheduled DNA synthesis assay in mammalian cells in cult-ire, no abnormal DNA synthesis was noted at any of the dose levels tested. Based on acceptable laboratory data, technical methoxycn ;.ur is characterized as very highly toxic to fish and aquatic invertebrates, and practically nontoxic to birds and bees. Hase-'i on theoretical calculations, both terrestrial and aquatic use'; oi methoxychlor may pose a hazard to aquatic organisms, although there is no field evidence to support this. The impacts oi methoxychlor use to nontarget organisms will be assessed upon receipt of ecological effects and environmental fate data, The environmental fate of methoxychlor cannot be characterized because acceptable data are lacking. Prelimi*)^.y data suggest that methoxychlor is unlikely to contaminate groundwater because of its low solubility and high rate of adsorption to soil particles. The nature of the residues of methoxychlor in plants and animals is not adequately understood. None of the tclerar-c- for methoxychlor is adequately supported. Plant and angina1 metabolism studies, residue studies, analytical methorlo ;oy^ processing studies, and storage stability data are needed be -co the Agency can determine the adequacy of current tolerance- levels. Chemical/Physical Characteristics of the Technical M.F.-;,e:±j±)_ Chemical/Physical Characteristics: Color: Data Gap Physical State: Crystalline solid (>?c.rir« Chemicals, 1987) Odor: Data Gap Melting Point: 89 °C (Farm Chemicals,, 1987) Specific Gravity: Data Gap Solubility: Very soluble in aromatic- chlorinated, or ketonic i e < v.-> ------- somewhat soluble in paraffinic types; essentially insoluble in water (Farm Chemicals, 1987) Vapor Pressure: Data Gap Flammability: Data Gap pH: Data Gap Toxicology Characteristics With the exception of one mutagenicity study, there are no acceptable acute, subchronic or long-term toxicology/oncogenicity studies available to support technical methoxychlor. In the mutagenicity study, a mammalian cell in culture unscheduled DMA synthesis assay (UDS assay), no increase in abnormal DNA synthesis was noted. Environmental Characteristics The Agency is unable to assess the environmental fate of methoxychlor because acceptable data are lacking. Preliminary data indicate that methoxychlor is stable to hydrolysis (half- life > 200 days); photodegradation in water (half-life of 4.5 months); and aerobic soil metabolism (half-life > 3 months in sandy loam soil). The half-life for anaerobic soil metabolism is reported at less than 1 month in sandy loam soil. Preliminary data also indicate that methoxychlor has a high adsorption rate to soil sediment (Kd value is 620). Ecological Characteristics Based on acceptable laboratory data, technical methoxychlor is characterized as practically nontoxic to birds on both an acute oral and subacute dietary basis and very highly toxic to fish and aquatic invertebrates on an acute basis. There is sufficient information to characterize methoxychlor as relatively nontoxic to honey bees. The acute toxicity value = 24 ug/bee. - Acute LD50 (bobwhite): >2510 mg/kg - Dietary LC50 >5620 ppm (upland gamebird) - Freshwater invertebrates toxicity (96-hr LC50) for daphnid .78 ppb - Fish acute toxicity (96-hr LC50) for rainbow trout: 1.31 ppm - Fish acute toxicity (96-hr LC50) for brook trout: 0.009 ppm Tolerance Assessment Tolerances have been established for residues of 4 ------- methoxychlor in a variety of raw agricultural commodities, in meat, fat and meat byproducts (40 CFR 180.120). Tolerances are expressed in terms of methoxychlor per se. The nature of the residues of methoxychlor in plants and animals is not adequately understood. None of the tolerances for methoxychlor is adequately supported. Plant and animal metabolism studies, residue studies, analytical methodology, processing studies, and storage stability data are needed before the Agency can determine the adequacy of current tolerance levels. The Preliminary Limiting Dose (PLD) of methoxychlor is .005 mg/kg/day. This is based on a rabbit teratology study with a No Observed Effect Level (NOEL) of 5 mg/kg/day for increased loss of litters and an uncertainty factor of 1000 to account for inter- and intraspecies differences, poor quality of the study used and total incompleteness of the subchronic and chronic toxicity data base. The study is not considered to be adequate to define a NOEL for purposes of setting an Acceptable Daily Intake, since the experimental design was considered to be inadequate. It is being used on an interim basis for calculation of the PLD. The Agency is unable to complete a tolerance assessment of methoxychlor because of the incompleteness of the toxicology and residue chemistry data bases. 4. SUMMARY OF REGULATORY POSITIONS AND RATIONALES Methoxychlor is not being placed into Special Review at this time. Since there are so few acceptable studies available to support registration of products containing methoxychlor, the Agency is not yet able to make a determination as to whether any of the criteria of 40 CFR 154.7 have been met or exceeded. The Agency will not approve any new food uses, including minor uses for this chemical since none of the tolerances are adequately supported. - The Agency is unable to assess methoxychlor's potential for contaminating groundwater. When data required in the Standard have been received and evaluated, the Agency will assess the potential for methoxychlor to contaminate groundwater. - Updated worker safety rules are required for end-use product labels. -The Agency is not establishing a longer reentry interval lot agricultural uses of methoxychlor beyond the minimum reentry interval (sprays have dried, dusts have settled, and vapors have dispersed). - Revised and updated fish and wildlife statements ar^ ------- required for end-use product labels. Since methoxychlor is practically nontoxic to bees, the bee statement imposed under under PR Notice 68-19 is no longer appropriate. Registrants must remove the bee statement from the labeling. - The Agency is not classifying methoxychlor as a restricted use pesticide at this time, since it is unable to determine if this pesticide meets any of the risk criteria of 40 CFR 152.170. Upon receipt of data required under this Standard, the Agency will apply the criteria of 40 CFR 152.170 to determine if any uses of methoxychlor warrant restricted use classification. - Since methoxychlor is an analogue of DDT, the Agency is requiring specific analysis of methoxychlor for the potential impurities 1,1,l-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) and other structurally similar compounds. SUMMARY OF OUTSTANDING DATA REQUIREMENTS Toxicology Acute Oral Toxicity Acute Dermal Toxicity Acute Inhalation Toxicity Eye Irritation Dermal Irritation Dermal Sensitization 21-Day Dermal Toxicity Chronic Testing (rodent) Chronic Testing (non-rodent) Oncogenicity (rat) Oncogenicity (mouse) Teratogenicity (rat) Teratogenicity (rabbit) Reproduction Gene Mutation Other Mechanisms of Mutagenicity Metabolism Time Frame 9 Months 9 Months 9 " 9 " 9 " 9 " 9 " 50 " 50 " 50 " 50 " 15 " 15 " 39 " 9 " 12 " 24 " Environmental Fate/Exposure Hydrolysis Photodegradation in Water Photodegradation on Soil Aerobic Soil Metabolism Anaerobic Soil Metabolism Anaerobic Aquatic Metabolism Aerobic Aquatic Metabolism Leaching and Adsorption/ Desorption 9 Months 9 " 9 " 27 " 27 " 27 " 27 " 12 " ------- Aquatic Dissipation Forestry Soil, Long-term Confined Rotational Crop Accumulation in Irrigated Crops Accumulation in Fish Accumulation in Aquatic Nontarget Organisms Fish and Wildlife Avian Reproduction Freshwater Fish LC5Q Studies (TEP) Freshwater Invertebrate LC5Q Studies (TEP) Estuarine and Marine Organisms LC5Q Studies (TEP) Fish Early Life Stage and Invertebrate Life Cycle Simulated or Actual Field Testing-Aquatic Organisms Seed Germination/Seedling Emergence Aquatic Plant Growth Residue Chemistry Residue data - Raw Agricultural Commodities Processing Studies Plant and Animal Metabolism Storage Stability Residue Analytical Methods Product Chemistry All Data 27 " 27 " 39 " 39 " 39 " 12 " 12 " 24 Months 9 " 9 " 12 " 15 " 24 " 9 " 9 " 18 Months 24 " 18 " 15 " 15 " 9 -15 Months 6. Contact Person at EPA Dennis H. Edwards Jr. Product Manager (12) Insecticide-Rodenticide Branch Registration Division (TS-767) Environmental Protection Agency Washington, DC 20460 Tel. No. (703) 557-2386 ------- DISCLAIMER: The information presented in this Chemical Information Fact Sheet is a summary only and may not be used to | fulfill data requirements for pesticide registration and " reregistration. ------- &EPA U.S. Environmental Protection Agency Office of Pesticide Program (TS-757C) PMSD, Information Services Branch 401 M Street, S.W. Washington, D.C. 20460 Official Business Penalty for Private Use $300 First Class Mail Postage and Fees Paid EPA Permit No. G-35 ------- |