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CAPTAFOL (DIFOL

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: 2425-06-1; Chemical Formula: C10H9Cl4NO2S

OSHA formerly had no permissible exposure limit for captafol. The proposed limit for captafol was an 8-hour TWA of 0.1 mg/m3, with a skin notation. The 0.1 mg/m3 limit, which is consistent with that of the ACGIH, is the PEL included in this final rule; however, OSHA is not including in the final rule the skin notation proposed for this substance. NIOSH (Ex. 8-47, Table N6A) concurred with the Agency's selection of a PEL for captafol, which is a white, crystalline substance with a slight but characteristic odor.

In humans, skin irritation, skin sensitization, and respiratory sensitization have been reported in both American and Japanese studies of farmers applying captafol as a fungicide. Arimatsu (1970/Ex. 1-1010) reported that farmers using captafol have experienced acute contact dermatitis manifesting as erythematous dermatitis and phototoxic eruptions. Kahn (1975, as cited in ACGIH 1986/Ex. 1-3, p. 97) reported that workers cleaning up in an area where captafol was handled experienced skin and respiratory sensitization.

The ACGIH (1986/Ex. 1-3) reported that the dermal LD(50) for captafol is greater than 9 g/kg in rabbits, indicating that the substance is not readily absorbed through the skin. As discussed in Section VI.C.18, OSHA has determined that skin notations are appropriate only when there is evidence that indicates that dermal contact may lead to skin absorption and increase the potential for systemic poisoning. Since this is not the case for captafol, OSHA finds that a skin notation is not warranted.

A two-year study conducted by the World Health Organization (Reinhardt and Brittelli 1981/Ex. 1-1063) reported growth depression in rats at captafol dietary levels of 1500 and 5000 ppm, and histopathologic examination revealed changes in the livers and kidneys of the animals exposed at these levels. In male rats, an increase in liver-to-body-weight ratio was observed at levels of 250 ppm and higher after 12 months of captafol feeding (Reinhardt and Brittelli 1981/Ex. 1-1063). No tumors were observed in this study. However, NIOSH (Ex. 8-47, Table N6A) submitted comments on captafol showing that several newer studies have demonstrated that captafol is a broad-spectrum carcinogen in mice and rats (Ito et al. 1984; EPA 1984, 1985, 1987). In 1987, the EPA cancelled the registration for captafol on the basis of this substance's carcinogenicity in laboratory animals; the EPA considers captafol a Category C substance, i.e., a possible human carcinogen. OSHA is aware of these recent studies on captafol's carcinogenicity and finds that they lend urgency to the establishment of a PEL for this previously unregulated substance. NIOSH's was the only comment OSHA received on this substance.

In the final rule, the Agency is establishing a permissible exposure limit for captafol of 0.1 mg/m3 as an 8-hour TWA to protect workers against the significant risk of contact dermatitis and respiratory and skin irritation and sensitization, all material impairments of health, that are associated with exposure to captafol at the levels formerly permitted by the absence of an OSHA limit. The Agency concludes that this 8-hour TWA PEL will substantially reduce these significant risks.

 

 
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