EPA 749-F-94-020a CHEMICAL SUMMARY FOR PERCHLOROETHYLENE 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 These sources include online databases, unpublished EPA information, government publications, review documents, and standard reference materials. No attempt has been made to verify information contained in these databases and secondary sources. I. CHEMICAL IDENTITY AND PHYSICAL/CHEMICAL PROPERTIES The chemical identity and physical/chemical properties of perchloroethylene are summarized in Table 1. TABLE 1. CHEMICAL IDENTITY AND CHEMICAL/PHYSICAL PROPERTIES OF PERCHLOROETHYLENE ___________________________________________________________________________ Characteristic/Property Data Reference ___________________________________________________________________________ CAS No. 127-18-4 Common Synonyms Perc; PCE; tetrachloroethylene; ethylene tetrachloride Budavari et al. 1989 Molecular Formula C2Cl4 Chemical Structure Cl-C=C-Cl | | Cl Cl Physical State colorless liquid Budavari et al. 1989 Molecular Weight 165.85 Budavari et al. 1989 Melting Point -22øC Budavari et al. 1989 Boiling Point 121øC Budavari et al. 1989 Water Solubility <1 mg/L at 22øC Keith and Walters 1985 Density d15/4, 1.6311 g/mL Budavari et al. 1989 Vapor Density (air = 1) 5.7 HSDB 1994 KOC 665 U.S. Air Force 1989 Log KOW 3.40 HSDB 1994 Vapor Pressure 18.47 mm Hg at 25øC HSDB 1994 Reactivity Flash Point nonflammable ATSDR 1993 Henry's Law Constant 1.8 x 10-2 atm m3/mol ATSDR 1993 Fish Bioconcentration Factor 39 (rainbow trout, Oncorhynchus mykiss) 49 (bluegill, Lepomis macrochirus) U.S. EPA 1988 Odor Threshold 1.0 ppm (in air) ATSDR 1993 Conversion Factors 1 ppm = 6.78 mg/m3 1 mg/m3 = 0.15 ppm Torkelson and Rowe 1981 ___________________________________________________________________________ II. PRODUCTION, USE, AND TRENDS A. Production There are 3 companies producing perchloroethylene at 4 facilities in the United States. Table 2 lists producers, plant locations, and plant capacities. Annual US production capacity is estimated at 400 million pounds per year. Production reached 310 million pounds in 1991, with exports of 50 million pounds and imports of 80 million pounds (Mannsville 1992). B. Use The largest use for perchloroethylene is in dry cleaning and textile operations, accounting for an estimated 60 percent of all perchloro- ethylene use in the US in 1991. It is also used in the production of chlorofluorocarbons; in vapor degreasing and metal cleaning operations; in aerosol formulations; as a carrier for rubber coatings, solvent soaps, printing inks, adhesives, sealants, polishes, lubricants, and silicones; and as a solvent in various consumer products, such as typewriter correction fluid and shoe polishes. Table 3 shows the estimated 1991 end-use pattern for perchloroethylene. C. Trends Demand for perchloroethylene dropped by more than 35 percent from 1989 to 1991. Demand is expected to continue to decrease because of increased solvent recycling activities and lower production of perchloroethylene's principal derivative, CFC-113 (freon 113). TABLE 2. United States Producers of Perchloroethylene ___________________________________________________________________________ Company Plant Location(s) Plant Capacity (in millions of pounds) ___________________________________________________________________________ Dow Chemical Plaquemine, LA 90 PPG Industries Lake Charles, LA 110 Vulcan Chemicals Geismar, LA 150 Wichita, KS 50 ___________________________________________________________________________ Source: Mannsville 1992. TABLE 3. Estimated 1991 United States End-Use Pattern for Perchloroethylene __________________________________________________________________________ Use of Perchloroethylene Percentage of US (typical Standard Industrial Perchloroethylene Use Classification (SIC) Code)(see end note 1) ___________________________________________________________________________ Dry cleaning and textile mill (production, SIC 2842; use 22, 7216) 60% Chlorofluorocarbon production (SIC 2869) 20% Vapor degreasing and metal cleaning (use, various industries) 15% Miscellaneous (no applicable SIC Code(s)) 5% ___________________________________________________________________________ Source: Mannsville 1992. III. ENVIRONMENTAL FATE A. Environmental Release Due to the volatility and end-use pattern of perchloroethylene, 80-85% of the chemical used annually is released into the atmosphere with only 1% to water. Releases occur primarily through evaporation from the dry cleaning industry or from effluent from manufacturing and processing facilities (ATSDR 1993). In 1992, more than 12.3 million pounds of perchloroethylene were released to the atmosphere, 10 thousand pounds to surface water, 13 thousand pounds to underground injection sites, and 9 thousand pounds to land from U.S. facilities (TRI92 1994). Atmospheric emissions measured 1.7 ppb in samples taken 1.5 meters above the soil at contaminated landfill sites, and 3 ppb in samples from stack effluents of waste incinerators (ATSDR 1993). Surface water samples from Lake St. Clair, Canada contained up to 0.473 ppb due to industrial wastes, and well water near a dry cleaning plant in Japan reached levels of 27,000 ppb (ATSDR 1993). Recycling methods for perchloroethylene produce contaminated sludges and filters which, when deposited to landfills, can result in leaching of the chemical into soils (ATSDR 1993). B. Transport Perchloroethylene volatilizes rapidly to the atmosphere from water and soil as predicted by a Henry's law constant of 1.8 x 10-2 atmùm3/mol (ATSDR 1993; U.S. Air Force 1989). Volatilization half- lives for perchloroethylene in typical surface waters were estimated to be 7 days, 1.4 days, and 5.6 days for pond, river, and lake waters, respectively (ATSDR 1993). Sorption and release from soils is dependent upon organic matter content, temperature, satur- ation, and salinity. Unsaturated topsoil demonstrates approximately 97% sorption of the total perchloroethylene present, however, in saturated deep soils, 26% of the chemical leaches to ground water (U.S. Air Force 1989). C. Transformation/Persistence 1. Air - Perchloroethylene is degraded in the atmosphere by reaction with photochemically produced hydroxyl radicals. The estimated half-life is about 96 days; phosgene and chloroacetyl- chlorides are the major degradation products (ATSDR 1993). 2. Soil - Approximately 2.2% of the perchloroethylene present in unsaturated top soils will volatilize into soil air but in saturated soils 26% leaches into ground waters (U.S. Air Force 1989). Substantial chemical sorption to soils is predicted by a relatively high KOC (665) indicating persistence for months to years (U.S. Air Force 1989). Small amounts of anaerobic micro- bial degradation may also occur (ATSDR 1993). 3. Water - Volatilization of perchloroethylene into the atmosphere is the major route of removal from water. Hydrolysis occurs very slowly or only at high temperatures (U.S. Air Force 1989). Photolytic degradation in surface waters (U.S. Air Force 1989) and microbial dehalogenation (ATSDR 1993) account for only a small amount of perchloroethylene loss from waters. 4. Biota - Bioaccumulation in aquatic organisms is not expected to be important based on the bioconcentration factors of 39 for rainbow trout (Oncorhynchus mykiss) or 49 for bluegill (Lepomis macrochirus) (U.S. EPA 1988). IV. HUMAN HEALTH EFFECTS A. Pharmacokinetics 1. Absorption - The main route of human exposure to perchloro- ethylene is through the respiratory tract, with intake via the gastrointestinal tract being less common. Perchloroethylene is rapidly absorbed into the blood from inspired air and the amount absorbed is dependent upon chemical concentration, lean body mass, level of activity during exposure, respiratory minute volume, and duration of exposure (ATSDR 1993; U.S. EPA 1988). Perchloroethylene is not absorbed well by the skin. This is not likely to be a significant route of exposure (Torkelson and Rowe 1981). 2. Distribution - Following inhalation exposure of perchloro- ethylene by humans, the chemical is sequestered in fat and fatty organs (ATSDR 1993). Perchloroethylene has been detected in the breath of individuals more than 14 days after termination of exposure by inhalation (ATSDR 1993). Following oral exposure to animals, perchloroethylene was detected in subcutaneous fat, liver, and kidney (ATSDR 1993). There is also limited evidence indicating the chemical can cross the placenta and distribute to the fetus (ATSDR 1993). 3. Metabolism - Perchloroethylene is metabolized by the liver cytochrome P-450 system to trichloroacetic acid (TCA), which is the major urinary metabolite, and trichloroethanol. However, urinary TCA levels reach a plateau indicating that the system is saturable (ATSDR 1993). 4. Excretion - The majority of an absorbed dose of perchloro- ethylene, whether oral or inhalation, is excreted as parent compound via exhalation (ATSDR 1993). Less than 1% of an estimated absorbed dose was excreted as urinary metabolites by humans exposed to 144 ppm perchloroethylene for 4 hours. Percentages of exhaled parent compound versus urinary metabolites vary slightly with other species (ATSDR 1993). B. Acute Toxicity Humans exposed to intermediate to high levels of perchloroethylene in air experience eye and respiratory irritation, dizziness, incoordination, and unconsciousness. Animal studies indicate perchloroethylene adversely affects the central nervous system and the liver. 1. Humans - The Dow Chemical Company has summarized human inhal- ation data as follows: 50 ppm, very faint odor, no physiological effects; 100 ppm, faint odor; 200 ppm, definite odor, moderate eye irritation, mild light-headedness; 400 ppm, strong odor, eye and nasal irritation, incoordination within 2 hours; 600 ppm, strong, unpleasant odor, eye and nasal irritation, dizziness within 10 minutes; 1000 ppm, very strong odor, severe irritation to eyes and respiratory tract, dizziness within 2 minutes; 1500 ppm, nauseating odor, extreme irritation to eyes and respiratory tract, complete incoordination within minutes, unconsciousness within 30 minutes (Torkelson and Rowe 1981). An oral dose of 500 mg/kg of perchloroethylene was not lethal in humans (Torkelson and Rowe 1981). 2. Animals - The lowest inhalation doses causing death in rats or mice within 4 hours were 3786 ppm and 2613 ppm, respectively (NTP 1986). Signs of toxicity included hypoactivity and anesthesia. Hepatocellular vacuolization occurred in mice after exposure to 200 ppm for 4 hours (ATSDR 1993) and after 1750 ppm for 14 days (NTP 1986). Oral LD50 values for perchlor- oethylene range from 2600 mg/kg for rats to >5 g/kg for mice. No deaths were reported for dogs or cats at 4000 mg/kg or for rabbits at 5000 mg/kg (Torkelson and Rowe 1981). C. Subchronic/Chronic Toxicity Adverse liver and kidney effects have been observed in workers exposed to perchloroethylene. Prolonged exposure to perchloro- ethylene can defat the skin, causing irritation, dryness, and dermatitis. EPA has derived an oral reference dose (RfD) (see end note 2) of 0.01 mg/kg/day for perchloroethylene, based on increased liver weight and reduction of body weight in animals drinking water containing perchloroethylene. 1. Humans - Liver damage such as hepatomegaly, icterus, and elevated, serum SGOT and SGPT (no estimates of dose given), as well as altered renal function (14 year average; TWA of 10 ppm), have been reported for workers exposed occupationally to perchloroethylene (ATSDR 1993). Prolonged and frequently repeated dermal exposure can cause irritation, dryness, and dermatitis due to defatting (Torkelson and Rowe 1981). 2. Animals - Mice exposed by inhalation to 400 ppm perchloro- ethylene for 13 weeks had lesions in the liver consisting of leukocytic infiltrations, centrilobular necrosis, and bile stasis (NTP 1986). Dose-related renal tubular karyomegaly was observed in rats (0, 200, 400 ppm) and mice (0, 100, 200 ppm) over a 2 year inhalation study (NTP 1986). Perchloroethylene, administered by gavage to mice at 0 to 2000 mg/kg/day, 5 days/week, for 6 weeks, caused liver toxicity at doses of 100 mg/kg/day and higher (U.S. EPA 1994). In another study, rats administered 14, 400, or 1400 mg/kg/day in drinking water for 13 weeks had decreased body weight gain and equivocal hepatic toxicity; a no-observed-adverse-effect-level (NOAEL) for this study was 14 mg/kg/day (ATSDR 1993). The U.S. EPA (1994) calculated a chronic reference dose for perchloroethylene of 0.01 mg/kg/day, based on the NOAEL for this study. D. Carcinogenicity EPA is currently assessing the carcinogenicity of perchloro- ethylene. There is inadequate evidence of carcinogenicity in humans; perchloroethylene has been shown to cause cancer in laboratory animals by both inhalation (rats and mice) and oral (mice) exposures. 1. Humans - Epidemiology studies of dry cleaning and laundry workers have failed to show clear evidence of carcinogenicity in humans exposed to perchloroethylene (ATSDR 1993). Confounding factors include concurrent exposure to petroleum based solvents, health habits such as smoking and alcohol consumption, and socioeconomic status. 2. Animals - Positive evidence for the carcinogenicity of perchloroethylene in F344 rats and B6C3F1 mice (50/sex/dose) was provided by a 2 year NTP study (1986). Animals were exposed by inhalation 6 hours/day, 5 days/week at concentra- tions of 0, 200, or 400 ppm for rats and 0, 100, or 200 ppm for mice. Perchloroethylene caused an increase in mononuclear cell leukemia in male and female rats and an increase in hepato- cellular adenomas and/or carcinomas in male and female mice. Some rare renal tubular cell carcinomas and brain gliomas were seen in male rats (NTP 1986). Positive evidence for the carcinogenicity of perchloroethylene in mice was provided by a 2 year NCI study (1977). Rats and mice (50/sex/dose) were exposed to perchloroethylene in corn oil by gavage 5 days/ week for 78 weeks. Doses were 0, 536, or 1072 mg/kg/day for male mice; 0, 386, or 772 mg/kg/day for female mice; 0, 471, or 941 mg/kg/day for male rats, and 0, 474, or 949 mg/kg/day for female rats. Perchloroethylene caused highly significant increases in hepatocellular carcinomas in mice (USEPA 1988). Perchloroethylene has been classified by IARC (1987) as 2B, inadequate evidence in humans but sufficient evidence in animals. A cancer assessment by the U.S. EPA is currently under review (U.S. EPA 1994). E. Genotoxicity IARC (1987) has reported percloroethylene as negative for gene mutations in Salmonella, for mitotic recombination and gene conversion in yeast, and for recessive lethals in Drosophila. IARC (1987) also has reported perchloroethylene as positive for cell transformation in Fischer rat embryo cells but not negative in BALB/C3T3 mouse cells. The chemical was negative for cell transformation in Syrian hamster embryo cells (GENETOX 1994). F. Developmental/Reproductive Toxicity The information on the developmental toxicity and reproductive system effects of perchloroethylene in humans and animals is limited. No conclusions can be made on the developmental and reproductive toxicity of perchloroethylene at this time. 1. Humans - No information was found in the secondary sources searched concerning developmental toxicity in humans from exposure to perchloroethylene. However, a limited number of reproductive studies on women in the dry cleaning industry reported an increase in menstrual disorders and spontaneous abortions. ATSDR (1993) has concluded that possible exposure to chemicals other than perchloroethylene precludes identifica- tion of perchloroethylene as the chemical responsible for the observed effects. 2. Animals - Perchloroethylene has not been shown to be teratogenic to rats, mice, or rabbits. Fetotoxicity at levels causing maternal toxicity was reported in rats and mice exposed to 300 ppm by inhalation on gestation days 6-15, but in another study, no effects were reported for rats exposed on days 1-19 or rabbits on days 1-24 of gestation to 500 ppm (ATSDR 1993). Rat pups of dams exposed to 900 ppm on gestation days 7-13 or days 14-20 had decreased performance on some ability tests initially; after about 2 weeks, pups exposed on gestation days 14-20 were superior to controls in rotorod and open field tests (ATSDR 1993; U.S. Air Force 1989). G. Neurotoxicity Evidence from both human and animal studies indicate that perchlor- oethylene adversely affects the central nervous system. The threshold for acute inhalation effects, including headaches, dizzi- ness, and incoordination, in humans is 100 ppm. 1. Humans - The central nervous system is a major target for perchloroethylene toxicity after either oral or inhalation exposure, with a threshold for acute inhalation toxicity in the range of 100-200 ppm (ATSDR 1993). Dizziness and drowsiness occurred in volunteers exposed to 216 ppm after 45 minutes, and loss of motor coordination occurred after 2 hours or 10 minutes of exposure to 280 ppm or 600 ppm, respectively (ATSDR 1993). Exposure to 100 ppm for 7 hours for 5 days resulted in headache, dizziness, difficulty in speaking, sleepiness, and loss of coordination (ATSDR 1993). The concentration of 100 ppm is roughly equivalent to 84.75 mg/kg/day (see end note 3). Acute symptoms in dry cleaning workers abated after termination of exposure; however, for some individuals exposed for one year or longer, memory and concentration impairment persisted (ATSDR 1993). 2. Animals - Clinical signs of neurotoxicity reported for experi- mental animals exposed to perchloroethylene include excita- bility, ataxia, hypoactivity, and loss of consciousness (ATSDR 1993). Mice exposed by inhalation to 2328 ppm for 4 hours show signs of anesthesia (NTP 1986). Dyspnea, hypoactivity, and ataxia were observed in rats and mice exposed to 1750 ppm for 6 hours/day, 5 days/week for 2 weeks (NTP 1986). V. ENVIRONMENTAL EFFECTS A. Toxicity to Aquatic Organisms Perchloroethylene has moderate acute toxicity to aquatic organisms; toxicity values are generally in the range between >1 mg/L and 100 mg/L. Ninety-six hour LC50 values for fish are 13.4-21.4 mg/L for Pimephales promelas (fathead minnow), 13 mg/L for Lepomis macrochirus (bluegill), and 5.0-5.8 mg/L for Oncorhynchus mykiss (rainbow trout) (AQUIRE 1994). The 96-hour EC50 for immobility in Pimephales promelas (fathead minnow) is 14.4 mg/L (AQUIRE 1994). Forty-eight hour LC50 and EC50's for Daphnia magna (water flea) are 9.1-18.0 mg/L and 7.5-8.5 mg/L, respectively; decreased growth and reproduction occurred at 1.1 mg/L for 28 days (AQUIRE 1994). Decreased photo- synthesis occurred in marine diatoms at 2 mg/L for 48 hours (AQUIRE 1994). B. Toxicity to Terrestrial Organisms No information was found in the secondary sources searched for toxicity of perchloroethylene to terrestrial organisms. However, based on the range of oral LD50's, 2600 mg/kg to 8850 mg/kg, for rats and mice, respectively, and the fact that no deaths were reported for dogs or cats at 4000 mg/kg or for rabbits at 5000 mg/kg (Torkelson and Rowe 1981), it is unlikely that the chemical will be toxic to terrestrial animals at environmental levels. Due to the high volatility of perchloroethylene, the chemical will not accumulate in soils or surface water in toxic concentrations. Lack of definitive developmental toxicity at high levels in laboratory animals suggests the chemical will not be teratogenic in other animals at environmental levels. C. Abiotic Effects Perchloroethylene reacts with hydroxyl radicals in the lower atmosphere to produce chloroacetylchlorides and phosgene (ATSDR 1993). The presence of these degradation products in air contribute to the production of photochemical smog (Federal Register 1992). Perchloroethylene is not likely to remain in the atmosphere long enough to reach the upper atmosphere as a significant source of ozone-destroying chlorine atoms. VI. EPA/OTHER FEDERAL/OTHER GROUP ACTIVITY Voluntary reduction of perchloroethylene environmental releases has occurred since 1991, as a result of a joint industry/EPA pollution prevention initiative known as the 33/50 program. The Clean Air Act Amendments of 1990 list perchloroethylene as a hazardous air pollutant. Occupational exposure to perchloroethylene is regulated by the Occu- pational Safety and Health Administration (OSHA). The permissible worker exposure limit is 100 parts per million parts of air (ppm) as an 8-hour time-weighted average (TWA) (29 CFR 1910.1000). Federal agencies and other groups that can provide additional information on perchloroethylene are summarized in Tables 4 and 5. TABLE 4. EPA OFFICES AND CONTACT NUMBERS FOR INFORMATION ON PERCHLOROETYLENE ________________________________________________________________________ EPA OFFICE LAW PHONE NUMBER ________________________________________________________________________ Pollution Prevention Toxic Substances Control Act & Toxics (Sec. 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 & Comprehensive Environmental Emergency Response Response, Compensation, and Liability Act (Superfund)/ Resource Conservation and Recovery Act / EPCRA (Sec. 304/311/312) (800) 424-9346 Water Clean Water Act (202) 260-7588 Safe Drinking Water Act (Drinking Water Standard: 0.005 mg/L) (800) 426-4791 ___________________________________________________________________________ TABLE 5. OTHER FEDERAL OFFICES/OTHER GROUPS CONTACT NUMBERS FOR INFORMATION ON PERCHLOROETHYLENE ___________________________________________________________________________ Other Agency/Department/Other Group Contact Number ___________________________________________________________________________ Agency for Toxic Substances & Disease Registry (404) 639-6000 American Conference of Governmental Industrial Hygienists (Recommended Exposure Limit (see end note 4): 25 ppm) (Recommended Short Term Exposure Limit (see end note 5): 100 ppm) (513) 742-2020 Consumer Product Safety Commission (301) 817-0994 National Institute for Occupational Safety & Health (Recommended Exposure Limit: Lowest Feasible Concentration; 0.4 ppm Limit of Quantitation) (800) 356-4674 Occupational Safety & Health Administration (Permissible Exposure Limit (see end note 6): 100 ppm) (Check your local phone book under U.S. Department of Labor) ___________________________________________________________________________ VII. END NOTES 1. Standard Industrial Classification code is the statistical classifi- cation standard for all Federal economic statistics. The code provides a convenient way to reference economic data on industries of interest to the researcher. SIC codes presented here are not intended to be an exhaustive listing; rather, the codes listed should provide an indication of where a chemical may be most likely to be found in commerce. 2. The RfD is an estimate (with uncertainty spanning perhaps an order of magnitude) of the daily exposure level for the human population, including sensitive subpopulations, that is likely to be without an appreciable risk of deleterious effects during the time period of concern. 3. Calculated using the factor 6.78 (Torkelson and Rowe 1981) to convert 100 ppm to 678 mg/m3 which is multiplied by 0.125 (the occupational 7-hour breathing rate, 8.75 m3 [standard 8-hour breathing rate, 10 m3] divided by the assumed adult body weight, 70 kg, and assuming 100% absorption) to obtain the dose in mg/kg/day (U.S. EPA 1988a). 4. The ACGIH recommended exposure limit is a time-weight average (TWA) con- centration for an 8-hour workday for a 40-hour workweek. 5. This is a recommended 15-minute exposure limit that should not be exceeded at any time. 6. The OSHA exposure limit is a time-weighted average (TWA) concentration that must not be exceeded during an 8-hour workshift during a 40-hour work- week. VIII. CITED REFERENCES ATSDR. 1993. Agency for Toxic Substances and Disease Registry. Toxicological Profile for Tetrachloroethylene. Update. ATSDR, Atlanta, GA, 151 pp. AQUIRE. 1994. EPA ERL-Duluth's Aquatic Ecotoxicology Data Systems. U.S. EPA, Duluth, MN. Retrieved July 1994. 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