OSHA's previous exposure limit for bromine was 0.1 ppm as an 8-hour TWA. OSHA proposed to supplement this TWA limit with a STEL of 0.3 ppm, the same limit recommended by the ACGIH, and NIOSH (Ex. 8-47, Table N1) concurred with this proposal. In the final rule, the Agency is establishing a 0.1-ppm TWA limit and a 0.3-ppm STEL for bromine. Bromine is a dark, reddish-brown, noncombustible, diatomic liquid that has irritating vapors.
Early studies of bromine exposure indicated that workers exposed to 0.75 ppm for 6 hours exhibited no symptoms (Flury and Zernik 1931a, as cited in ACGIH 1986/Ex. 1-3, p. 65). Later studies reported physiological responses to different concentrations of bromine and used these findings to make the following recommendations: the maximum allowable concentration for prolonged exposures should be 0.1 to 0.15 ppm, and the maximum allowable concentration for short-term exposures (i.e., 30 minutes to one hour) should be 4 ppm (Henderson and Haggard 1943b, as cited in ACGIH 1986/Ex. 1-3, p. 65). These investigators found levels of 40 to 60 ppm dangerous for short-term exposures, and a level of 1000 ppm proved rapidly fatal even during short exposures. These authors reported that the effects of exposure to bromine include respiratory irritation and lung edema. Elkins (1959a/Ex. 1106) reported that workers exposed to 1 ppm in a plant handling liquid bromine found this level excessively irritating.
OSHA received no comments on its proposed STEL for bromine, other than the NIOSH concurrence statement. The Agency finds that both the TWA and the short-term limits are necessary to substantially reduce the risk of respiratory irritation and lung damage that could occur following short-term exposures to concentrations of bromine that would be permitted by the 8-hour TWA limit alone. OSHA considers the effects related to bromine exposure material impairments of health. Therefore, OSHA is revising the limit for bromine to 0.1 ppm as an 8-hour TWA and 0.3 ppm as a 15-minute STEL.