HEXAFLUOROACETONE

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: 684-16-2; Chemical Formula: C₃F₆O

Previously, OSHA had no limit for hexafluoroacetone. The ACGIH has a TLV-TWA of 0.1 ppm, with a skin notation, for this colorless, nonflammable, highly reactive gas. The proposed PEL was an 8-hour TWA of 0.1 ppm, with a skin notation. NIOSH (Ex. 8-47) concurred with these limits, which are established by the final rule.

Inhalation studies of hexafluoroacetone in animals have shown varied systemic toxicities, including injury to the liver, kidney, testes, thymus, and bone marrow. In rats and dogs exposed six hours/day, five days/week for 13 weeks at concentrations of about 0.1, 1.0, or 12 ppm, no effects (other than increased lung weights in dogs) were observed in either species at 0.1 ppm. However, the 12-ppm exposures produced severe effects in both species, including marked but reversible testicular damage and slight hypoplasia of the spleen, thymus, and lymph nodes (E.I. du Pont de Nemours & Company, Inc. 1971, as cited in ACGIH 1986/Ex. 1-3,p. 303). Reversible kidney damage in rats and increased lung weights in dogs occurred during the 1.0-ppm exposures. An earlier four-hour acute exposure of rats demonstrated that 300 ppm was a lethal concentration (E.I. du Pont de Nemours and Co., Inc. 1971, as cited in ACGIH 1986/Ex. 1-3, p. 303).

In rats, two-week dermal exposures of 65, 130, or 250 mg/kg resulted in numerous adverse effects, including testicular damage and corresponding changes in lipid metabolism (Kennedy, Henry, Chen, and Dashiell 1982/Ex. 1-1038). A dermal dose of 13 mg/kg produced no adverse effects in rats (Lee and Gillies 1984/Ex. 1-561). An injected dose of radiolabeled hexafluoroacetone was, for the most part, rapidly excreted in the urine in unmetabolized form; this material also did not accumulate in rat testes (Gillies and Rickard 1984/Ex. 1-322). Brittelli and co-workers (1979/Ex. 1-300) reported that hexafluoroacetone was fetotoxic in rats. Dermal application of 90 mg/kg/day to pregnant rats resulted in maternal toxicity. Fetal toxicity occurred at maternal doses of 25 mg/kg, and fetal size was reduced at maternal doses of 5 and 25 mg/kg; however, 1 mg/kg produced no fetal effect. Although soft-tissue damage and external abnormalities were observed, teratogenicity could not be demonstrated definitively (Brittelli, Culik, Dashiell, and Fayerweather 1979/Ex. 1-300). Other than the comment by NIOSH (Ex. 8-47), OSHA received no comments on this substance.

The final rule establishes an 8-hour TWA PEL of 0.1 ppm TWA and a skin notation for hexafluoroacetone. The Agency concludes that these limits, taken together, will protect workers from the significant risk of systemic injuries at multiple organ sites, reproductive effects, kidney damage, and fetotoxic effects, all of which constitute material health impairments that are associated with exposure to hexafluoro-acetone at levels above the new PEL.