SULFUR PENTAFLUORIDE

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: 5714-22-7; Chemical Formula: S₂F₁₀

The previous OSHA limit for sulfur pentafluoride was 0.025 ppm as an 8-hour TWA. OSHA proposed revising this limit to 0.01 ppm as a ceiling, and NIOSH (Ex. 8-47, Table N1) concurred with this proposal. The Agency is establishing this limit in the final rule. This limit is consistent with the ACGIH (1986/Ex. 1-3) recommended limit. Sulfur pentafluoride is a colorless gas or liquid with a sulfur-dioxide-like odor.

Sulfur pentafluoride’s toxic effects include lung congestion and lesions, and pulmonary edema. In a study in which rats were exposed to sulfur pentafluoride for 16 to 18 hours, levels of 0.1 ppm caused lung irritation, 0.5 ppm resulted in severe pulmonary lesions, and 1 ppm proved fatal (Greenberg and Lester 1950/Ex. 1-590). One-hour exposures to 10 ppm sulfur pentafluoride resulted in diffuse hemorrhagic lesions in the lungs of rats, while rats exposed to 1 ppm for one hour had severe congestion of the lungs. Rats exposed for one hour to 0.1 ppm showed no effects. Subsequent examination of rats surviving the 10- and 1-ppm exposures revealed that the lungs had returned to normal after 24 hours (Greenberg and Lester 1950/Ex. 1-590). Saunders, Shoshkes, DeCarlo, and Brown (1953/Ex. 1-610) established that the LD(50) for sulfur penta-fluoride in rabbits is 5.8 mg/kg, and that death was due to fulminant pulmonary edema. According to this study, sulfur pentafluoride does not injure the columnar epithelium of the respiratory tract, and exposure is not followed by bronchopneumonia.

Other than NIOSH’s submission, OSHA received no comments on its proposal to revise the sulfur pentafluoride limit to 0.01 ppm as a ceiling. The 0.01-ppm ceiling was selected on the basis of evidence showing that even brief exposures to 1 ppm caused pulmonary effects in animals and prolonged exposures to 0.1 ppm caused lung irritation in animals. OSHA concludes that this limit for sulfur pentafluoride will reduce the risks of irritation and pulmonary effects to which workers could be exposed in the absence of a ceiling limit. The Agency considers these effects material impairments of health. Therefore, OSHA is promulgating a ceiling limit for sulfur pentafluoride of 0.01 ppm.