HYDROGEN BROMIDE

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: 10035-10-6; Chemical Formula: HBr

The previous OSHA PEL for hydrogen bromide was 3 ppm as an 8-hour TWA. The Agency proposed revising this limit to 3 ppm as a ceiling limit not to be exceeded at any time during the working day; NIOSH (Ex. 8-47, Table N1) concurred with this proposal. In the final rule, OSHA is establishing this ceiling limit, which conforms to the recommendation made by the ACGIH. Hydrogen bromide (HBr) is a colorless, corrosive, nonflammable gas with an acrid odor.

Animal studies have demonstrated that hydrogen bromide has a considerably higher acute toxicity than hydrogen chloride (HCl) in mice and a somewhat higher acute toxicity than this chemical in rats (NIOSH 1977i/Ex. 1-1182). In mice, the LC(50) is 800 ppm HBr in air for 60 minutes (and 2500 ppm HCl in air for 30 minutes); in rats, the LC(50) is 2800 ppm HBr in air for 60 minutes (and 5000 ppm HCl in air for 30 minutes).

The chief toxic effect of hydrogen bromide in humans is primary irritation of the nose and throat. Irritation begins within several minutes at levels of between 3 and 6 ppm. At 2 ppm, the odor of HBr is detectable, but no irritation is experienced (Connecticut State Department of Health 1955, as cited in ACGIH 1986/Ex. 1-3, p. 312). No chronic effects have been associated with exposure to hydrogen bromide. No comments, other than NIOSH’s, were received on this substance.

OSHA finds that, under its previous 3-ppm TWA limit, workers were at significant risk of experiencing irritant effects due to short-term exposures to levels of hydrogen bromide exceeding 3 ppm. The Agency considers the irritant effects of exposure to hydrogen bromide to be material impairments of health. Therefore, OSHA is establishing a 3-ppm ceiling limit for this substance in the final rule to limit short-term exposures to hydrogen bromide and reduce this risk.