PERCHLORYL FLUORIDE

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: 7616-94-6; Chemical Formula: ClO₃F

OSHA’s former 8-hour TWA limit for perchloryl fluoride was 3 ppm. The ACGIH has a TLV-TWA of 3 ppm and a STEL of 6 ppm for this colorless gas with a sweet odor. The proposal retained the 8-hour TWA PEL of 3 ppm for perchloryl fluoride and added a STEL of 6 ppm. NIOSH (Ex. 8-47, Table N1) concurs that these limits are appropriate, and they are established in the final rule.

The 4-hour LC(50)s in rats and mice were 385 and 630 ppm, respectively. Dogs exposed for 4 hours to 220- to 450-ppm concentrations of the vapor, followed by exposure to 620 ppm for 2.5 hours, became hyperpneic and cyanotic and showed increased methemoglobin. Dogs succumbing to these exposures had pigment deposition in the liver, spleen, and bone marrow; alveolar hemorrhage and collapse; and emphysema (Greene, Colbourn, Donati, and Weeks 1960, as cited in ACGIH 1986/Ex. 1-3, p. 466).

Exposure to 185 ppm for six hours/day, five days/week for seven weeks killed 18 of 20 rats, 20 of 39 mice, and all exposed guinea pigs (Greene, Colbourn, Donati, and Weeks 1960, as cited in ACGIH 1986/Ex. 1-3, p. 466). These animals had difficulty breathing, became cyanotic, and developed alveolar edema and methemoglobinemia; at autopsy, they showed fluorosis, patchy lungs, enlarged spleens, and hemosiderosis of the kidneys, spleen, and liver. When animals were exposed on a similar regimen but to a concentration of 104 ppm for six weeks, all guinea pigs but only 1 of 20 rats died (Greene, Colbourn, Donati, and Weeks 1960, as cited in ACGIH 1986/Ex. 1-3, p. 466). After a six-month exposure to 24 ppm, bone fluoride levels increased fourfold in guinea pigs, threefold in rats, and about 50 percent in dogs. Animals exposed at 24 ppm showed no signs of irritation (Greene, Colbourn, Donati, and Weeks 1960, as cited in ACGIH 1986/Ex. 1-3, p. 466). Only NIOSH commented on perchloryl fluoride.

In the final rule, OSHA is retaining the 8-hour TWA of 3 ppm and adding a STEL of 6 ppm for perchloryl fluoride. These limits are based on the fluoride content of this compound. The Agency concludes that this combined limit will protect workers from the significant risk of fluorosis and hematologic effects, which together constitute material impairments of health that are associated with exposures to perchloryl fluoride at levels above these limits.