AEGL-3 values were based on lethality studies in rats exposed to bromoacetone at concentrations of 1-131 ppm and for durations of 6-120 min (Dow Chemical 1968). The threshold for lethality at each AEGL-3 exposure duration was calculated using probit analysis, based on the dose-response program of ten Berge (2006) (see Appendix B). The threshold for lethality was set at LC01 (lethal concentration, 1% lethality). The LC01 was chosen over the BMCL05 (benchmark concentration, 95% lower confidence limit with 5% response) because values derived using the BMCL05 were less consistent with human data (2.5 ppm for 10 min, 0.94 ppm for 30 min, 0.44 ppm for 1 h, 0.089 ppm for 4 h, and 0.039 ppm for 8 h; and only ocular irritation was found in humans exposed at 0.1 and 1.0 ppm). A time-scaling value of 1.3 (C1.3 × t = k) was derived from the data. Interspecies and intraspecies uncertainty factors of 3 each were applied (total of 10), because bromoacetone is an irritant (causes lacrimation, nasal discharge, gasping, wheezing, and labored breathing in rats and ocular irritation in humans), and clinical signs are likely caused by a direct chemical effect on the tissues. This type of portal-of-entry effect is not likely to vary greatly between species or among individuals.
The AEGL values for bromoacetone are summarized in Table 2-1.
Bromoacetone is a colorless liquid that rapidly turns violet, even in the absence of air. It has a pungent odor. It was first used as a chemical weapon during World War I, and was referred to as BA by the British and B-stoff (white cross) by the Germans. It might currently be used in organic synthesis, although production data were not found. It is prepared by treating acetone with bromine and sodium chlorate. Bromoacetone occurs naturally in the essential oil of a seaweed species that grows in the ocean around the Hawaiian Islands (HSDB 2011). Chemical and physical data for bromoacetone is provided in Table 2-2.
TABLE 2-1 AEGL Values for Bromoacetone
|Classification||10 min||30 min||1 h||4 h||8 h||End Point (Reference)|
|AEGL-1 (nondisabling)||0.011 ppm (0.062 mg/m3)||0.011 ppm (0.062 mg/m3)||0.011 ppm (0.062 mg/m3)||0.011 ppm (0.062 mg/m3)||0.011 ppm (0.062 mg/m3)||Ocular irritation in humans (Dow Chemical 1968)|
|AEGL-2 (disabling)||1.4 ppm (7.8 mg/m3)||0.57 ppm (3.2 mg/m3)||0.33 ppm (1.8 mg/m3)||0.11 ppm (0.62 mg/m3)||0.063 ppm (0.35 mg/m3)||One-third AEGL-3 values|
|AEGL-3 (lethality)||4.1 ppm (23 mg/m3)||1.7 ppm (9.5 mg/m3)||0.98 ppm (5.5 mg/m3)||0.32 ppm (1.8 mg/m3)||0.19 ppm (1.1 mg/m3)||Threshold for lethality (LC01) in rats (Dow Chemical 1968)|