CAPTAN

OSHA comments from the January 19, 1989 Final Rule on Air Contaminants Project extracted from 54FR2332 et. seq. This rule was remanded by the U.S. Circuit Court of Appeals and the limits are not currently in force.

CAS: 133-06-2; Chemical Formula: C₉H₈Cl₃NO₂S

OSHA did not formerly regulate captan. The ACGIH has a TLV-TWA of 5 mg/m³ for this substance, which is a white, crystalline, odorless solid. The proposed PEL was an 8-hour TWA of 5 mg/m³, and the final rule promulgates this limit.

Skin applications of 900 mg/kg captan produce skin irritation in experimental animals. Long-term feeding studies did not reveal adverse effects in dogs fed captan in the diet at levels of 100 mg/kg/day for 66 weeks or in rats fed 1000 mg/kg/day for two years (Martin 1971/Ex. 1-1161; Spencer 1968, as cited in ACGIH 1986/Ex. 1-3, p. 98). Male mice showed decreased fertility at levels of 50 or 100 mg/kg/day for five days (Collins 1972/Ex. 1-893).

Studies on the mutagenicity of captan indicate that the substance acts as an alkylating agent and induces chromosome rearrangements in rats and point mutations in Neurospora crassa (Epstein and Legator, as cited in ACGIH 1986/Ex. 1-3, p. 98). Legator and colleagues (1969, as cited in ACGIH 1986/Ex. 1-3, p. 98) reported that captan concentrations of 10 ug/ml inhibited DNA in human embryo cells, and concentrations of 1.5 ug/ml produced chromosomal aberrations in the somatic and germ cells of kangaroo rats. Animal evidence concerning the carcinogenicity of captan is contradictory, although high doses caused significant incidences of polyploid carcinoma of the duodenum and adenomatous polyps in mice (NCI 1977a, as cited in ACGIH 1986/Ex. 1-3, p. 98).

Some captan-exposed individuals experience skin irritation (Spencer 1968, as cited in ACGIH 1986/Ex. 1-3, p. 98). A case of recurrent urticaria caused by captan exposure has been reported and confirmed (Croy 1973/Ex. 1-894), and captan caused high reactivity when administered in a battery of patch tests (Rudner 1977/Ex. 1-967).

NIOSH (Ex. 8-47, Table N6A) concurs with the limit being established, but notes that captan could be classified as a potential occupational carcinogen. No other comments were received on this substance.

In the final rule, OSHA is establishing a PEL of 5 mg/m³ TWA to protect workers exposed to captan from the significant risk of exposure-related skin irritation, reproductive effects, mutagenicity, and, perhaps, carcinogenicity, all of which constitute material health impairments. The Agency concludes that this limit will substantially reduce these significant risks.