EPA 749-F-94-022a CHEMICAL SUMMARY FOR 1,2,4-TRIMETHYLBENZENE prepared by OFFICE OF POLLUTION PREVENTION AND TOXICS U.S. ENVIRONMENTAL PROTECTION AGENCY August 1994 This summary is based on information retrieved from a systematic search limited to secondary sources (see Appendix A). These sources include online databases, unpublished EPA information, government publi- cations, review documents, and standard reference materials. No attempt has been made to verify information in these databases and secondary sources. I. CHEMICAL IDENTITY AND PHYSICAL/CHEMICAL PROPERTIES The chemical identity and physical/chemical properties of 1,2,4-trimethylbenzene are summarized in Table 1. TABLE 1. CHEMICAL IDENTITY AND CHEMICAL/PHYSICAL PROPERTIES OF 1,2,4-TRIMETHYLBENZENE ___________________________________________________________________________ Characteristic/Property Data Reference ___________________________________________________________________________ CAS No. 95-63-6 Common Synonyms pseudocumene, pseudocumol, asymmetrical trimethyl- benzene Budavari et al. 1989 Molecular Formula C9H12 Chemical Structure C6H5(CH3)3 Physical State colorless liquid Verschueren 1983 Molecular Weight 120.19 Budavari et al. 1989 Melting Point -43.78øC Budavari et al. 1989 Boiling Point 169-171øC Budavari et al. 1989 Water Solubility 57 mg/L at 20øC Verschueren 1983 Density d20/4, 0.876 g/mL Budavari et al. 1989 Vapor Density (air = 1) 4.15 Verschueren 1983 KOC 472 U.S. EPA 1987a Log KOW 3.78 U.S. EPA 1987a Vapor Pressure 2.03 mm Hg at 25øC U.S. EPA 1987a Reactivity flammable when heated HSDB 1994 Flash Point 54.4øC Sandmeyer 1981 Henry's Law Constant 5.18 x 10-3 atmùm3/mol U.S. EPA 1987a Fish Bioconcentration Factor 439 (estimated) U.S. EPA 1987a Odor Threshold 0.4 ppm (in air) Verschueren 1983 Conversion Factors 1 ppm = 4.92 mg/m3 1 mg/m3 = 0.2 ppm Sandmeyer 1981 ___________________________________________________________________________ II. PRODUCTION, USE, AND TRENDS A. Production Production of 1,2,4-trimethylbenzene occurs during petroleum refining as a major component of the C9 aromatic hydrocarbon fraction (or simply the C9 fraction). It typically constitutes around forty percent of the C9 fraction with other trimethyl- benzenes and ethyltoluenes making up the remainder of this fraction. Nearly 200 refineries in the United States produce the C9 fraction at an estimated annual volume of 80 billion pounds (U.S. EPA 1991). Only one company (Koch Refining) in the United States currently isolates 1,2,4-trimethylbenzene. In 1981, production was estimated to be greater than 4,540 kilograms. Proprietary sources and Toxics Release Inventory (TRI) data indicate 1992 production volume to be much higher. EPA estimates in excess of 10 million pounds of 1,2,4-trimethylbenzene to be isolated annually. Imports reached approximately 5.41 million kilograms in 1981. No export data are available (HSDB 1994; U.S. International Trade Commission 1994). B. Use The primary use of the C9 fraction, approximately 99% of its production volume, is as a gasoline additive. Uses of the remaining C9 fraction (approximately 350 million pounds) include those as a solvent in coatings; cleaners; pesticides; and printing and inks. Information on 80% of the domestic production of C9 fraction solvents indicate the median ethyltoluene and trimethyl- benzene content is 80% with a range of 75%-90% (U.S. EPA 1991). Isolated 1,2,4-trimethylbenzene is used in a number of industrial applications. It is used chiefly as the raw material for production of trimellitic anhydride. It is also used in the manu- facture of pharmaceuticals and dyes (Sax and Lewis 1987). C. Trends Though no production forecasts have been made for 1,2,4-trimethyl- benzene, TRI data indicate releases to have been stable for the three-year period 1990-1992. III. ENVIRONMENTAL FATE A. Environmental Release Of the total 1,2,4-trimethylbenzene released to the environment in 1992, 5.3 million pounds were released into the atmosphere, 8 thousand pounds released into surface water, 14 thousand pounds to underground injection sites, and 511 thousand pounds released onto the land (TRI92 1994). Average atmospheric concentrations in the U.S. range from 0.58 ppb in rural areas to 1.20 ppb in urban areas (U.S. EPA 1988a). Drinking water from Cincinnati, OH contained 1,2,4-trimethylbenzene concentrations of 0.127 microgram/L (U.S. EPA 1988a). The chemical has been detected in seawater from the Narragansett Bay (Rhode Island) at concentrations ranging from 0.002 - 0.540 microgram/L (U.S. EPA 1988a). B. Transport 1,2,4-Trimethylbenzene volatilizes rapidly from surface waters as predicted by a Henry's law constant of 5.18 x 10-3 (vapor pressure, 2.03 mm Hg) (U.S. EPA 1987a). The volatilization half-life from a model river is calculated to be 3.4 hours (U.S. EPA 1988a). The chemical also volatilizes from soils, however, based on an estimated KOC of 472, moderate adsorption to soils and sediments may occur (U.S. EPA 1987a). C. Transformation/Persistence 1. Air - Degradation of 1,2,4-trimethylbenzene in the atmosphere occurs by reaction with hydroxyl radicals (U.S. EPA 1987a). Reaction also occurs with ozone but very slowly (half life, 8820 days) (CHEMFATE 1994). In the atmosphere, two estimates of the half-life are approximately 6 hours (U.S. EPA 1987a) and, in the presence of hydroxyl radicals, 0.5 days (CHEMFATE 1994). 2. Soil - Volatilization is the major route of removal of 1,2,4- trimethylbenzene from soils; although, biodegradation may also occur (U.S. EPA 1987a). 3. Water - Because of 1,2,4-trimethylbenzene's water solubility and its vapor pressure of 2.03 mm Hg, the chemical will rapidly volatilize from surface waters (U.S. EPA 1987a). Biodegradation of 1,2,4-trimethylbenzene occurred with inoculums from both seawater and ground water (U.S. EPA 1988a), but, no details or degradation products were given. Various strains of Pseudomonas can biodegrade 1,2,4-trimethylbenzene (U.S. EPA 1988a), but, again no details were included. 4. Biota - The estimated bioconcentration factor (439) and high volatility of 1,2,4-trimethylbenzene indicates that bioaccumula- tion of the chemical will not be significant (U.S. EPA 1987a). IV. HUMAN HEALTH EFFECTS A. Pharmacokinetics 1. Absorption - Absorption of 1,2,4-trimethylbenzene occurs after oral, inhalation, or dermal exposure. Occupationally, inhalation and dermal exposures are the most important routes of absorption (U.S. EPA 1988a) although systemic intoxication from dermal absorption is not likely to occur (HSDB 1994) due to the dermal irritation caused by the chemical prompting quick removal. Following oral administration of the chemical to rats, 62.6% of the dose was recovered as urinary metabolites indicating substantial absorption (U.S. EPA 1987a). 2. Distribution - 1,2,4-Trimethylbenzene is lipophilic and may accumulate in fat and fatty tissues. In the blood stream, approximately 85% of the chemical is bound to red blood cells (U.S. EPA 1988a). 3. Metabolism - Metabolism occurs by side-chain oxidation to form alcohols and carboxylic acids which are then conjugated with glucuronic acid, glycine, or sulfates for urinary excretion (U.S. EPA 1988a). After a single oral dose to rats of 1200 mg/kg, urinary metabolites consisted of approximately 43.2% glycine, 6.6% glucuronic, and 12.9% sulfuric acid conjugates (HSDB 1994; U.S. EPA 1988a). The two principle metabolites excreted by rabbits after oral administration of 438 mg/kg/day for 5 days were 2,4-dimethylbenzoic acid and 3,4-dimethylhippuric acid (HSDB 1994; U.S. EPA 1988a). 4. Excretion - The major routes of excretion of 1,2,4-trimethyl- benzene are exhalation of parent compound and elimination of urinary metabolites. Half-times for urinary metabolites were reported as 9.5 hours for glycine, 22.9 hours for glucuronide, and 37.6 hours for sulfuric acid conjugates (U.S. EPA 1988a). B. Acute Toxicity Direct contact with liquid 1,2,4-trimethylbenzene is irritating to the skin and breathing the vapor is irritating to the respiratory tract causing pneumonitis. Breathing high concentrations of the chemical vapor causes headache, fatigue, and drowsiness. 1. Humans - Liquid 1,2,4-trimethylbenzene is irritating to the skin and inhalation of vapor causes chemical pneumonitis (HSDB 1994). High concentrations of vapor (5000-9000 ppm) cause headache, fatigue, and drowsiness (HSDB 1994). The concentration of 5000 ppm is roughly equivalent to a total of 221 mg/kg assuming a 30 minute exposure period (see end note 1). 2. Animals - Mice exposed to 8130-9140 ppm 1,2,4-trimethylbenzene (no duration given) had loss of righting response and loss of reflexes (Sandmeyer 1981). Direct dermal contact with the chemical (no species given) causes vasodilation, erythema, and irritation (U.S. EPA 1988a). Seven of 10 rats died after an oral dose of 2.5 mL of a mixture of trimethylbenzenes in olive oil (average dose approximately 4.4 g/kg) (U.S. EPA 1988a). Rats and mice were exposed by inhalation to a coal tar distillate contain- ing about 70% 1,3,5- and 1,2,4-trimethylbenzene; no pathological changes were noted in either species after exposure to 1800-2000 ppm for up to 48 continuous hours, or in rats after 14 exposures of 8 hours each at the same exposure levels (U.S. EPA 1988a). No effects were reported for rats exposed to a mixture of trimethyl- benzenes at 1700 ppm for 10 to 21 days (HSDB 1994). C. Subchronic/Chronic Toxicity Long-term exposure to solvents containing 1,2,4-trimethylbenzene may cause nervousness, tension, and bronchitis. 1. Humans - Painters that worked for several years with a solvent containing 50% 1,2,4- and 30% 1,3,5-trimethylbenzene showed nervousness, tension and anxiety, asthmatic bronchitis, anemia, and alterations in blood clotting; hematological effects may have been due to trace amounts of benzene (U.S. EPA 1987a; HSDB 1994). 2. Animals - Rats were given 1,2,4-trimethylbenzene orally at doses of 0.5 or 2.0 g/kg/day, 5 days/week for 4 weeks. All rats exposed to the high dose died and 1 rat in the low dose died (no times given); no other effects were reported (U.S. EPA 1987b). Rats exposed by inhalation to 1700 ppm of a trimethylbenzene isomeric mixture for 4 months had decreased weight gain, lymphopenia and neutrophilia (HSDB 1994). D. Carcinogenicity No information was found on the carcinogenicity of 1,2,4 trimethyl- benzene. Results of mutagenicity (see Section IV.E) testing, requested by and submitted to EPA under Section 4 of the Toxic Substances Control Act (TSCA), did not trigger carcinogenicity testing for the C9 fraction. 1. Humans - No information was found in the secondary sources searched regarding the carcinogenicity of 1,2,4-trimethylbenzene in humans. 2. Animals - No information was found in the secondary sources searched regarding the carcinogenicity of 1,2,4-trimethylbenzene to animals. The chemical is not listed among the chemicals studied or to be studied by the National Toxicology Program (NTP 1994). E. Genotoxicity No information was found in the secondary sources searched regarding the genotoxicity of 1,2,4-trimethylbenzene. Results of mutagenicity testing, requested by and submitted to EPA under Section 4 of TSCA, indicate that the C9 fraction does not induce gene mutations in prokaryotes (Salmonella tymphimurium/mammalian microsome assay); or in mammalian cells in culture (in Chinese hamster ovary cells with and without activation). The C9 fraction does not does not induce chromosome mutations in Chinese hamster ovary cells with and without activation; does not induce chromosome aberrations in the bone marrow of Sprague-Dawley rats exposed by inhalation (6 hours/day for 5 days); and does not induce sister chromatid exchange in Chinese hamster ovary cells with and without activation. F. Developmental/Reproductive Toxicity No information was found in the secondary sources searched regarding the reproductive/ developmental effects of 1,2,4-trimethylbenzene. Results of testing, requested by and submitted to EPA under Section 4 of TSCA, indicate that the C9 fraction can adversely affect the reproductive system and the developing offspring. Testing results indicate that the C9 fraction has a lowest-observed-effect level (LOEL) of 100 ppm (210 mg/kg/day in mice) for developmental effects and a LOEL of 100 ppm (100 mg/kg/day in rats) for reproductive effects. 1. Humans - No information was found in the secondary sources searched regarding the developmental or reproductive toxicity of 1,2,4-trime- thylbenzene in humans. 2. Animals - No information was found in the secondary sources searched regarding the developmental or reproductive toxicity of 1,2,4-tri- methylbenzene in animals. In response to a TSCA Section 4 test rule, a three-generation repro- ductive study on the C9 fraction was conducted by the International Research and Development Corporation for the American Petroleum Institute. CD rats (30/sex/group) were exposed by inhalation to the C9 fraction at concentrations of 0, 100, 500, or 1500 ppm (0, 100, 500, or 1500 mg/kg/day) for 6 hours/day, 5 days/week. EPA has concluded that there was evidence of parental and reproductive toxicity at all dose levels. Indicators of parental toxicity included reduced body weights, increased salivation, hunched posture, aggressive behavior, and death. Indicators of adverse reproductive system effects included reduced litter size and reduced pup body weight. The LOEL was 100 ppm; a no-observed-effect level was not established (Seed 1989). No effects on fecundity or fertility occurred in rats treated dermally with up to 0.3 mL/rat/day of a mixture of trimethyl- benzenes, 4-6 hours/day, 5 days/week over one generation (Chevron 1985). In response to a TSCA Section 4 test rule, a developmental toxicity study on the C9 fraction was conducted by the International Research and Development Corporation for the American Petroleum Institute. CD-1 mice (30/dose group) were exposed by inhalation to the C9 fraction at concentrations of 0, 100, 500, or 1500 ppm (0, 210, 1100, or 3200 mg/kg/day) for 6 hours/day during days 6 through 15 of gestation. EPA has concluded that there was evidence of develop- mental toxicity at all dose levels. Indicators of adverse develop- mental effects included increased frequency of whole litter resorptions, reduced pup viability, and malformations (cleft palate, unossified sternebrae, and reduced skull ossification). The LOEL was 100 ppm; a no-observed-effect level was not established (Campbell 1989). Developmental toxicity, including possible develop- mental neurotoxicity, was evident in rats in the above described 3-generation reproductive study (Seed 1989). G. Neurotoxicity 1,2,4-Trimethylbenzene depresses the central nervous system. Exposure to solvent mixtures containing the chemical causes headache, fatigue, nervousness, and drowsiness. Results of testing, requested by and submitted to EPA under Section 4 of TSCA, are flawed. Results of the developmental toxicity study (see Section IV F) indicate that the C9 fraction caused adverse neurological effects at the highest dose (1500 ppm) tested. 1. Humans - 1,2,4-Trimethylbenzene is a central nervous system depressant (Budavari et al. 1989). Occupationally, workers exposed to a solvent containing 50% 1,2,4-trimethylbenzene had nervousness, headaches, drowsiness, and vertigo (U.S. EPA 1988a). Headache, fatigue, and drowsiness were reported for workers exposed (no dose given) to paint thinner containing 80% 1,2,4- and 1,3,5-trimethylbenzenes (HSDB 1994). 2. Animals - Mice exposed to 8130-9140 ppm (no duration given) of 1,2,4-trimethylbenzene had loss of righting response and loss of reflexes (Sandmeyer 1981). In response to a TSCA Section 4 test rule, a neurotoxicity study was conducted by the Experimental Pathology Laboratories for the American Petroleum Institute. Male Sprague-Dawley rats (20/dose group) were exposed by inhalation to the C9 fraction at concen- trations of 0, 100, 500, or 1500 ppm (0, 100, 500, or 1500 mg/kg/day) for 6 hours/day, 5 days/week for 13 weeks (Rees 1989). No adverse neurotoxicity effects were noted, but several critical limitations to the study were noted by EPA reviewers. No further neurotoxicity tested was recommended (McMaster 1990). Neurobehavioral effects were noted in mice exposed in the develop- mental toxicity study on the C9 fraction (Section IV.F). In the high dose (1500 ppm) group observations included abnormal gait, labored breathing, weakness, excessive salivation, reduced activity, impaired hindlimb function, tremors, and lack of righting reflex. No observed adverse changes were reported at the lower doses (100 ppm and 500 ppm). V. ENVIRONMENTAL EFFECTS 1,2,4-Trimethylbenzene has moderate acute toxicity to aquatic organisms; acute toxicity values fall within the range of greater than 1 mg/L and 100 mg/L. LC50 values for specific aquatic organisms range from approx imately 5 to 8 mg/L (AQUIRE 1994) which is orders of magnitude greater than any measured concentration in seawater (0.002 - 0.54 microgram/L) (U.S. EPA 1988a). The high concentrations required to induce toxicity in laboratory animals are not likely to be reached in the environment. A. Toxicity to Aquatic Organisms Ninety-six hour LC50 values are 7.72 mg/L for Pimephales promelas (fathead minnow) and 5.1 mg/L for Cancer magister (dungeness crab, first instar) (AQUIRE 1994). No stress was observed in Oncorhynchus mykiss (rainbow trout, fingerling) or Petromyzon marinus (sea lamprey, larvae) at 5 mg/L for 24 hours (AQUIRE 1994). The 48 hour EC50 for Daphnia magna (water flea) is 3.61 mg/L (AQUIRE 1994). B. Toxicity to Terrestrial Organisms No information was found in the secondary sources searched for toxicity of 1,2,4-trimethylbenzene to terrestrial organisms. However, due to the high volatility of the chemical (vapor pressure, 2.03 mm Hg), it is unlikely to accumulate in soil or surface water to toxic concentrations. C. Abiotic Effects According to the definition provided in the Federal Register (1992), 1,2,4-trimethylbenzene is a volatile organic compound (VOC) substance. As a VOC, 1,2,4-trimethylbenzene can contribute to the formation of photochemical smog in the presence of other VOCs. VI. EPA/OTHER FEDERAL ACTIVITY Occupational exposure to 1,2,4-trimethylbenzene is regulated as trimethylbenzenes. The Occupational Safety and Health Administration's time weighted average (TWA) permissible exposure limit for trimethyl- benzenes is 25 ppm. Federal agency activity for 1,2,4-trimethylbenzene is summarized in Tables 2 and 3. TABLE 2. EPA OFFICES AND CONTACT NUMBERS FOR INFORMATION ON 1,2,4-TRIMETHYLBENZENE. ___________________________________________________________________________ EPA Office Statute Contact Number ___________________________________________________________________________ Pollution Prevention & Toxics PPA (202) 260-1023 EPCRA (sec. 313/TRI) (800) 424-9346 TSCA (202) 554-1404 Solid Waste & Emergency Response EPCRA (sec. 311/312) (800) 424-9346 ________________________________________________________________________ EPA OFFICE LAW PHONE NUMBER ________________________________________________________________________ Pollution Prevention Toxic Substances Control Act & Toxics (sec. 4/8A/8D/8E) (202) 554-1404 Emergency Planning and Community Right-to-Know Act (EPCRA) Regulations (Sec. 313) (800) 424-9346 Toxics Release Inventory data (202) 260-1531 Air Clean Air Act (919) 541-0888 Solid Waste & EPCRA (Sec. 311/312) (800) 424-9346 Emergency Response ________________________________________________________________________ TABLE 3. OTHER FEDERAL OFFICE CONTACT NUMBERS FOR INFORMATION ON 1,2,4-TRIMETHYLBENZENE. ________________________________________________________________________ Other Agency/Department Contact Number ________________________________________________________________________ Consumer Products Safety Commission (301) 504-0994 National Institute for Occupational Safety & Health (800) 356-4674 (Exposure Limit for Trimethylbenzenes (see end note 2): 25 ppm) Occupational Safety & Health Administration (Exposure Limit for Trimethylbenzenes (see end note 3): 25 ppm) (Check local phone book for phone number under Department of Labor) ___________________________________________________________________________ VII. END NOTES 1. Calculated using the factor 4.92 (Sandmeyer 1981) to convert 5000 ppm to 24,600 mg3/m which is multiplied by 0.009 (breathing rate for 30 minutes, 0.625 m3 [standard occupational 8-hour breathing rate, 10 m3] divided by the assumed adult body weight, 70 kg) to obtain the dose in mg/kg (U.S. EPA 1988b). 2. The NIOSH exposure limit is a recommended time-weighted average (TWA) concentration for total trimethylbenzene isomers for up to a 10-hour workday during a 40-hour work week. 3. The OSHA exposure limit is a time-weighted average (TWA) concentration for total trimethylbenzene isomers for up to a 10-hour workday during a 40-hour work week. VIII. CITED REFERENCES AQUIRE. 1994. EPA ERL-Duluth's Aquatic Ecotoxicology Data Systems. U.S. EPA, Duluth, MN. Retrieved August 1994. Budavari S, O'Neil MJ, Smith A, Heckelman PE (Eds.). 1989. The Merck Index, 11th ed. Rahway, NJ: Merck & Co., Inc., p. 1258. Campbell. 1989. Detailed review of C9 aromatic hydrocarbons. Memorandum from M. Campbell, Toxics Effects Branch to C. Auer, Health and Environ- mental Review Division, Office of Toxic Substances, U.S. EPA. Washington, D.C. CHEMFATE. 1994. Syracuse Research Corporation's Environmental Fate Data Bases, retrieved 8/5/94. Syracuse Research Corporation, Syracuse, NY. Chevron. 1985. One generation reproduction study of PED 5450 in rats with cover letter. Washington, D.C.: Office of Toxic Substances, U.S. EPA. EPA Doc. No. 878214973. Federal Register. 1992. Part 51 - Requirements for Preparation, Adoption, and Submittal of Implementation Plans. Fed. Reg. 57:3945. HSDB. 1994. Hazardous Substances Data Bank. MEDLARS Online Information Retrieval System, National Library of Medicine. Retrieved July 1994. McMaster. 1990. Review of neurotox test data for the C9 aromatic hydro- carbons. Memorandum from S. McMaster, Toxics Effects Branch to A. Auletta, Toxic Effects Branch, Office of Toxic Substances, U.S. EPA. Washington, D.C. NTP. 1994. National Toxicology Program. Management Status Report produced from Chemtrack System, National Library of Medicine. Rees. 1989. Section 4 testing of C9 aromatic hydrocarbons: Neurotoxicity data. Memorandum from C. Rees, Toxics Effects Branch to C. Auer, Health and Environmental Review Division, Office of Toxic Substances, U.S. EPA. Washington, D.C. Sandmeyer EE. 1981. Aromatic hydrocarbons. In: Patty's Industrial Hygiene and Toxicology, 3rd ed., Vol. 2B, GD Clayton and FE Clayton, Eds. New York: John Wiley & Sons. Sax NI, Lewis RJ, Eds. 1987. Condensed Chemical Dictionary, Eleventh Edition, Van Nostrand Reinhold Co., New York. Seed. 1989. Review of Section 4 study - Three generation reproduction/ fertility study in rats with C9 aromatic hydrocarbons. Memorandum from J. Seed, Toxics Effects Branch to N. Chudhari, Test Rules Development Branch, Office of Toxic Substances, U.S. EPA. Washington, D.C. TRI92. 1994. 1992 Toxics Release Inventory. Office of Pollution Prevention and Toxics, U.S. EPA, Washington, D.C., p. 94. U.S. EPA. 1987a. U.S. Environmental Protection Agency. Health Effects Assessment for Trimethylbenzenes. Office of Research and Development, U.S. EPA, Washington, D.C., 12 pp. ECAO-CIN-H059. U.S. EPA. 1987b. U.S. Environmental Protection Agency. Reportable Quantity Document for Pseudocumene. Office of Research and Development, U.S. EPA, Washington, D.C., 2 pp. U.S. EPA. 1988a. U.S. Environmental Protection Agency. Drinking Water Health Advisory for 1,2,4-Trimethylbenzene. Office of Research and Develop- ment, U.S. EPA, Washington, D.C., 14 pp. ECAO-CIN-W029. U.S. EPA. 1988b. U.S. Environmental Protection Agency. Methodology for Evaluating Potential Carcinogenicity in Support of Reportable Quantity Adjustments Pursuant to CERCLA Section 102. Carcinogen Assessment Group, Office of Health and Environmental Assessment, U.S. EPA, Washington, D.C., pp. 21, 22. OHEA-C-073. U.S. EPA. 1991. U.S. Environmental Protection Agency. RAB Pre-RM1 Presentation for the C9 Aromatic Hydrocarbon Fraction. Risk Assessment Branch (prepared by E. Brandt), Existing Chemicals Division, Office of Toxic Substances, U.S. EPA, Washington, D.C. U.S. International Trade Commission. 1994. Synthetic Organic Chemicals. United States Production and Sales, 1992. February 1994. Verschueren K (Ed). 1983. Handbook of Environmental Data on Organic Chemicals, 2nd ed. New York: Van Nostrand Reinhold Co., pp. 1162-1163. APPENDIX A. SOURCES SEARCHED FOR FACT SHEET PREPARATION AQUIRE. 1994. Aquatic Information Retrieval online data base. Chemical Information Systems, Inc., a subsidiary of Fein-Marquart Assoc. ATSDR. 1989-1994. Agency for Toxic Substances and Disease Registry. Toxicological Profiles. Chamblee, GA: ATSDR. Budavari S, O'Neil MJ, Smith A, Heckelman PE (Eds.). 1989. The Merck Index, 11th ed. Rahway, N.J.: Merck & Co., Inc. CHEMFATE. 1994. Syracuse Research Corporation's Environmental Fate Data Bases. Syracuse Research Corporation, Syracuse, NY. Clayton GD, Clayton FE, Eds. 1981-1982. Patty's Industrial Hygiene and Toxicology, 3rd ed. New York: John Wiley & Sons. GENETOX. 1994. U.S. EPA GENETOX Program, computerized database. HSDB. 1994. Hazardous Substances Data Bank. MEDLARS Online Information Retrieval System, National Library of Medicine. IARC. 1979-1994. International Agency for Research on Cancer. IARC Monographs on the Evaluation of Carcinogenic Risk of Chemicals to Man. Lyon: IARC. NIOSH (National Institute for Occupational Safety and Health). 1992. NIOSH Recommendations for Occupational Safety and Health. Compendium of Policy Documents and Statements. Cincinnati, OH: NIOSH. NTP. 1994. National Toxicology Program. Toxicology and Carcinogenesis Studies. Tech Rep Ser. NTP. 1994. National Toxicology Program. Management Status Report. Produced from NTP Chemtrack system. April 8, 1994. National Toxicology Program, Research Triangle Park, NC. OSHA. 1994. Occupational Safety and Health Administration. Table Z-2. Limits for Air Contaminants. RTECS. 1994. Registry of Toxic Effects of Chemical Substances. MEDLARS Online Information Retrieval System, National Library of Medicine. U.S. Air Force. 1989. The Installation Restoration Toxicology Guide, Vols. 1-5. Wright-Patterson Air Force Base, OH. U.S. EPA (U.S. Environmental Protection Agency). 1991. Table 302.4 List of Hazardous Substances and Reportable Quantities 40 CFR, part 302.4:3-271. U.S. EPA. Most current. Drinking Water Regulations and Health Advisories. Office of Drinking Water, U.S. Environmental Protection Agency, Washington, D.C. U.S. EPA. Most Current. Health Effects Assessment Summary Tables. Cincinnati, OH: Environmental Criteria and Assessment Office, U.S.EPA. U.S. EPA reviews such as Health and Environmental Effects Documents, Health and Environmental Effect Profiles, and Health and Environmental Assess- ments. U.S. EPA. 1994. Integrated Risk Information System (IRIS) Online. Cincinnati, OH: Office of Health and Environmental Assessment.