BROMINE 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: 7789-30-2; Chemical Formula: BrF₅

OSHA had no former limit for bromine pentafluoride. The ACGIH has a TLV-TWA of 0.1 ppm. The proposed PEL was 0.1 ppm as an 8-hour TWA, and NIOSH (Ex. 8-47, Table N1) concurs with this limit. The final rule promulgates a 0.1-ppm 8-hour TWA PEL for bromine pentafluoride. This substance is a pale yellow liquid at temperatures below 40.3 deg. C; above this temperature, it is a colorless, pungent, corrosive gas.

Bromine pentafluoride has been shown to be acutely toxic in animals. Animals exposed to bromine pentafluoride vapor at 500 ppm exhibited immediate symptoms of gasping, swollen eyelids, clouded corneas, tearing, salivation, and acute distress; these symptoms appeared after exposure for a period as short as three minutes. Exposures to 50 ppm were fatal after 30 minutes, and chronic exposures above 3 ppm resulted in severe nephrosis (in some animals), as well as marked hepatosis and severe respiratory involvement (The Matheson Co., Inc., as cited in ACGIH 1986/Ex. 1-3, p. 66). Bromine pentafluoride is toxicologically more active than free, elemental fluorine, and its toxicity appears to be closely related to that of chlorine trifluoride (Horn and Weir 1955/Ex. 1-592; Horn and Weir 1956, as cited in ACGIH 1986/Ex. 1-3, p. 66). Chlorine trifluoride has caused severe toxicity and some fatalities in dogs and rats exposed over a period of six months to an average concentration of 1.17 ppm for six hours daily (Horn and Weir 1955/ Ex. 1-592).

In the final rule, OSHA is establishing a PEL of 0.1 ppm as an 8-hour TWA to prevent the significant risk of serious systemic injury potentially associated with exposure to this substance at levels above the new limit. The Agency concludes that this limit will substantially reduce this risk of systemic toxicity, which constitutes a material impairment of health..