Hazardous Chemical Information System (HCIS)

Perchloroethylene

Exposure Standard first adopted in 1990

Carcinogen category notice:

Category 2: Suspected human carcinogen. See section 3.6 of the Globally Harmonized System of Classification and Labelling of Chemicals (GHS) Third revised edition.

The placing of a substance in Category 2 is done on the basis of evidence obtained from human and/or animal studies, but which is not sufficiently convincing to place the substance in Category 1. Based on strength of evidence together with additional considerations, such evidence may be from either limited evidence of carcinogenicity in human studies or from limited evidence of carcinogenicity in animal studies.

No standard should be applied without reference to Guidance on the interpretation of Workplace exposure standards for airborne contaminants.

Documentation notice: National Occupational Health and Safety Commission documentation available for these values.

1. IDENTITY

2. CHEMICAL AND PHYSICAL PROPERTIES

Perchloroethylene is a clear, colourless, non-flammable liquid with an ether odour. Stabilisers which contain amines, epoxides or esters are added to prevent decomposition. Its chemical and physical properties include:

3. MAJOR INDUSTRIAL USES

The major uses of perchloroethylene are for commercial dry cleaning and metal degreasing. It also has minor use in products for home use.

4. METABOLISM

Perchloroethylene is absorbed mainly through inhalation, causing both irritation and neurobehavioural effects. Skin burns, blistering and erythema can occur from severe direct contact with perchloroethylene ⁽¹⁾ . Some skin absorption can occur but does not appear to be of major significance ⁽³⁾ .

Perchloroethylene is eliminated slowly through the lungs. A small amount is metabolised to trichloroethanol and trichloroacetic acid ⁽¹⁾ .

5. ANIMAL STUDIES

5.1 Toxic Effects

The oral LD₅₀ of perchloroethylene in mice was reported to be 6.4-10.8g/kg body weight. The four-hour inhalation LC₅₀ in mice was 5200ppm ⁽⁴⁾ .

Repeated exposures of rats, rabbits and guinea pigs to perchloroethylene vapour have produced pathological changes in the liver. At 400ppm, 130 seven-hour exposures over six months caused no effect in rats, rabbits, or monkeys, while guinea pigs have increased liver and kidney weights and slight fatty degeneration. Guinea pigs were found to be more susceptible than other species. Guinea pigs exposed at 200ppm exhibited slight to moderate pathological change in the liver. Liver weight increase but no histopathology was observed at 100ppm for seven months ⁽⁵⁾ .

Kylin et al ⁽⁶⁾ exposed mice to 200ppm perchloroethylene vapour for 4 hours/day for 1, 2, 4, or 8 weeks. The researchers reported fatty degeneration in the livers of the animals. No liver cell necroses were observed.

5.2 Carcinogenicity

The International Agency for Research on Cancer (IARC) has reviewed the carcinogenicity of perchloroethylene in experimental animals ^(4,7) .

Perchloroethylene was tested for carcinogenicity in mice and rats by gavage. In mice, it produced heptocellular carcinomas in both sexes. In the experiment with rats, no increases in tumour incidences were observed ⁽⁸⁾ .

In an inhalation study of rats, exposure to perchloroethylene produced an increased incidence of leukaemia ⁽⁹⁾ . Rampy et al ⁽¹⁰⁾ also reported an inhalational study in rats. Groups of rats were exposed to 300 or 600ppm perchloroethylene vapour for 12 months, followed by observation up to 30 months. No increases in tumour incidences were found.

6. HUMAN STUDIES

6.1 Acute Effects

Excessive exposure to perchloroethylene can have adverse effects on the central nervous system, mucous membranes, eyes, skin, lungs, liver and kidney. The effects on the central nervous system are always noted. Unconsciousness, dizziness, headache, vertigo or light narcosis have been reported in many instances after occupational exposure. An oral dose of 500mg/kg body weight did not cause death ⁽¹¹⁾ .

The first controlled inhalation study was reported by Rowe et al ⁽⁵⁾ . Exposure to 106ppm perchloroethylene vapour for one hour was not objectionable to any of the six subjects, while the concentration of 216ppm caused eye irritation and slight dizziness. These findings were also confirmed by the study of Stewart et al ⁽¹²⁾ .

Slight eye irritation was reported by six individuals who were exposed at concentrations of 100ppm for four hours ⁽¹³⁾ .

The (Swedish) National Board of Occupational Safety and Health has reviewed the toxicity of perchloroethylene ⁽²⁾ . Short-term exposure at 100ppm would cause temporary irritation to mucous membranes of the nose and throat. Prolonged (seven-hour) exposure at 100ppm could produce slight drowsiness, slight headache and/or dizziness. Irritation of the eyes, headache, drowsiness and dizziness would occur from short-term exposure at 200ppm.

6.2 Neurobehavioural Effects

Tuttle et al ⁽¹⁴⁾ examined 27 dry cleaners for neurobehavioural effects. Exposure of these workers to perchloroethylene was quite low; the 8-hour TWA being 18ppm in the exposed group. Occurrence of psychological problems and signs of functional disturbances in the peripheral nervous system were investigated. The researchers found no difference between the exposed and the control groups.

Hake and Stewart ⁽¹⁵⁾ exposed volunteer subjects to 20, 100 or 15ppm of perchloroethylene vapour over five consecutive days. The researchers found, in subjects exposed at 100ppm, a slight decrement in performance on on a coordination test, but no adverse health effects were observed. Additional behavioural and neurological tests revealed no interaction effects for perchloroethylene with alcohol or diazepam. The authors were of the view that an occupational exposure standard of 100ppm would not provide a sufficient margin of safety regarding unimpaired performance during during repeated exposures.

6.3 Carcinogenicity

The IARC ^(4,7) and US Environmental Protection Agency (EPA) ⁽¹⁶⁾ have reviewed the carcinogenicity of perchloroethylene in humans.

In several recent studies ^(17-23) , excesses of lymphosarcomas, leukaemias and cancers of the skin, colon, lung and urogenital tract were reported in laundry or dry-cleaning workers. However, the number of cases involved were small; and many of these studied workers were also exposed to other organic solvents, such as trichloroethylene and petroleum distillates. Moreover, in some of these studies, the dry-cleaning solvents used were not identified. Taken together, with all these discrepancies, these studies have not provided a satisfactory basis for drawing definitive conclusions.

7. OVERSEAS EXPOSURE STANDARDS

8. CONCLUSION

Perchloroethylene causes irritation at concentrations of 100-120ppm. Short-term exposure at 200ppm can result in irritation, dizziness, confusion, nausea and headache.

Perchloroethylene can cause narcotic and anaesthetic effects. Prolonged exposure at 100ppm resulted in a slight decrement in performance on coordination test but no observable health effect. An occupational exposure level of 100ppm does not appear to provide an adequate margin of safety.

There is limited evidence for carcinogenicity of perchlorethylene in experimental animals. Perchloroethylene has induced malignant tumours of the liver in mice. Exposure of rats through inhalation produced an increased incidence of leukaemia. Some other studies have not produced positive results.

There is inadequate evidence for carcinogenicity of perchloroethylene in humans.

9. RECOMMENDATION FOR EXPOSURE STANDARD

To prevent irritation and subjective complaints, the Exposure Standards Working Group recommends for perchloroethylene a time-weighted average exposure standard of 50ppm. A short-term exposure limit of 150ppm is also recommended. This level should be low enough to prevent anaesthetic effects.

After reviewing the relevant data, the Exposure Standards Working Group is of the view that perchloroethylene may have carcinogenic potential to humans, based on the limited evidence from animal studies. The Working Group recommends that perchloroethylene be classified as Category 3 Carcinogen (Substance Suspected of having Carcinogenic Potential). The reader is encouraged to review the section on Carcinogens in the Guidance Note on the Interpretation of Exposure Standards for Atmospheric Contaminants in the Occupational Environment for guidance on the classification system of carcinogens.

REFERENCES

1. American Conference of Governmental Industrial Hygienists (ACGIH), Documentation of the threshold limit values and biological exposure indices, 5th edition, Cincinnati, Ohio, 1986

2. National Board of Occupational Safety and Health, Consensus report for tetrachloroethylene, Scientific Basis for Swedish Occupational Standards, 1981:21, 34-39, Solna, Sweden, 1981

3. Stewart RD & Dodd HC, "Absorption of carbon tetrachloride, trichloroethylene, tetrachloroethylene, methylene chloride and 1,1,1-trichloroethane through human skin", Am Ind Hyg Assoc J 25, 439-446, 1964

4. International Agency for Research on Cancer, IARC Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans, Volume 20, IARC, Lyon, France, p.491-514, 1979

5. Rowe VK et al, "Vapor toxicity of tetrachloroethylene for laboratory animals and human subjects", Arch Ind Hyg, 5, 566, 1952

6. Kylin BJ et al, "Hepatotoxicity of inhaled trichloroethylene and tetrachloroethylene - long-term exposure", Acta Pharmacol Toxicol, 22, p.379, 1965

7. International Agency for Research on Cancer, IARC Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans, Suppl.7, IARC, Lyon, France, p.355-357, 1987

8. National Cancer Institute, Bioassay of tetrachloroethylene for possible carcinogenicity (Technical Report Series No.13), DHEW Publication No. (NIH)77-813, Washington DC, 1977

9. National Toxicology Program, Toxicology and carcinogenesis studies of tetrachloroethylene (perchloroethylene) (CAS No. 127-18-4) in F344/N rats and B6C3F1 mice (inhalation studies) (Tech Rep Serv No. 311; NIH Publ No. 86-2567), Research Triangle Park, NC, 1986

10. Rampy LW et al, "Results of long-term inhalation toxicity studies on rats of 1,1,1-trichloroethane and perchloroethylene formulations (Abstract)", In: International Congress on Toxicology, Toronto, Canada, 1977, p.27

11. National Institute for Occupational Safety and Health (NIOSH), Criteria for a recommended standard - occupational exposure to tetrachloroethylene, DHEW Pub No. (NIOSH) 76-155, 1976

12. Stewart RD et al, "Experimental human exposure to tetrachloroethylene", Arch Environ Health, 20, 224, 1970

13. Stewart RD et al, Tetrachloroethylene - development of a biologic standard for the industrial worker by breath analysis, Report No. NIOSH-MCOW-ENVM-PCE 76-6, The Medical Dept of Environmental Medicine, Milwaukee, WI, 1974

14. Tuttle T et al, "A behavioural and neurological evaluation of dry cleaners exposed to perchloroethylene", DHEW (NIOSH) Publication No. 77-214, Washington 1977

15. Hake CL & Stewart RD, "Human exposure to tetrachloroethylene: inhalation and skin contact", Envir Health Perspectives, 21, 231-238, 1977

16. US Environmental Protection Agency, Health AssesSment Document for Tetrachloroethylene (Perchloroethylene) EPA/600/8-82/005F, July 1985, Final Report, Research Triangle Park, NC

17. Katz RM et al, "Female laundry end dry cleaning workers in Wisconsin: a mortality analysis", Am J Public Health, 71, 305-307, 1981

18. Blair A et al, "Causes of death among laundry end dry cleaning workers", Am J Public Health, 69, 508-511, 1979

19. Kaplan SD, "Dry cleaners workers exposed to perchloroethylene. A retrospective cohort mortality study (PB81-231367), Springfield VA, National Technical Information Services, 1980

20. Duh RW & Asal NR, "Mortality among laundry and dry cleaning workers in Oklahoma", Am J Public Health, 74, 1278-1280, 1984

21. Brown DP & Kaplan SD, "Retrospective cohort mortality study of dry cleaner workers using perchloroethylene", J Occup Med, 29, 535-541, 1987

22. Blair A et al, "Mortality among dry cleaners", Med Lav, 77, 82-83, 1986

23. Smith EM et al, "Bladder cancer risk among laundry workers, dry cleaners, and others in chemically-related occupations", J Occup Med 27, 295-297, 1985

Footnotes:

Documentation notice:
Entries carrying a notice for National Occupational Health and Safety Commission documentation indicate that these substances have been reviewed in detail by the Exposure Standards Expert Working Group and that documentation supporting the adopted national values is available in the National Commission's Documentation of the Exposure Standards [NOHSC:10003(1995)].