Summarization Of Recent Literature Pertaining To An Occupational Health Standard For Methylene Chloride.
NIOSH 1980 Jun:103 pages
Methylene-chloride (74873) and human and animal toxicity studies, work practices and engineering controls, sampling and analysis, and research gaps in existing information are reviewed. Repeated exposure to methylene-chloride during the normal work cycle in workers produces the risk of accumulation of the chemical in adipose tissue. Performance decrements observed in methylene-chloride exposed workers is attributed to the main metabolite carbon-monoxide (630080). Animal studies show that exposure to methylene-chloride causes elevation in blood carboxyhemoglobin, which is due more to an increase in the rate of carbon-monoxide production than to a change in carbon-monoxide hemoglobin affinity. Hepatic microsomal cytochrome-P-450 mixed function oxygenase system catalyzes conversion of methylene-chloride to carbon-monoxide and chloride and a second metabolic pathway yields formaldehyde (50000) and inorganic halide. Evidence for mutagenicity in salmonella-typhimurium is suggestive at best. Results from mouse lung tumor bioassay are also suggestive of carcinogenic activity. In one epidemiologic study no increased risk for malignancy or circulatory disease is identified. Installation of methylene-chloride to the eyes of rabbits produce minor effects but no gross or micropathologic changes. Hepatic effects are produced in guinea-pigs following inhalation of methylene-chloride and the effects are accentuated by concurrent exposure to ethanol (64175). The authors conclude that data indicates a need to revise existing occupational health standards on methylene-chloride.
NIOSH-Contract; Safety-research; Industrial-safety; Poisons; Chlorides; Exposure-levels; Pulmonary-function-tests; Carcinogens; Mutation; Skin-exposure; Contract-210-78-0009;
74-87-3; 630-08-0; 50-00-0; 64-17-5;
NTIS Accession No.
NIOSH, Public Health Service, U.S. Department of Health, Education, and Welfare, Rockville, Maryland, NTIS PB83-238-527