AEGL-2 is the airborne concentration (expressed as ppm or mg/m3) of a substance above which it is predicted that the general population, including susceptible individuals, could experience irreversible or other serious, long-lasting adverse health effects or an impaired ability to escape.
AEGL-3 is the airborne concentration (expressed as ppm or mg/m3) of a substance above which it is predicted that the general population, including susceptible individuals, could experience life-threatening health effects or death.
Airborne concentrations below the AEGL-1 represent exposure concentrations that could produce mild and progressively increasing but transient and nondisabling odor, taste, and sensory irritation or certain asymptomatic, nonsensory effects. With increasing airborne concentrations above each AEGL, there is a progressive increase in the likelihood of occurrence and the severity of effects described for each corresponding AEGL. Although the AEGL values represent threshold concentrations for the general public, including susceptible subpopulations, such as infants, children, the elderly, persons with asthma, and those with other illnesses, it is recognized that individuals, subject to idiosyncratic responses, could experience the effects described at concentrations below the corresponding AEGL.
Bromoacetone is a colorless liquid with a pungent odor. It is described as a dermal, ocular, and respiratory irritant. Bromoacetone was first used as a chemical weapon during World War I, and may currently be used in organic synthesis, although production data were not found. Bromoacetone is prepared by treating acetone with bromine and sodium chlorate. It occurs naturally in the essential oil of a seaweed species that grows in the ocean around the Hawaiian Islands (HSDB 2011).
AEGL-1 values for bromoacetone were based on a concentration of 0.1 ppm that caused ocular irritation in humans (Dow Chemical 1968). An intraspecies uncertainty factor of 3 was applied because contact irritation is a portal-of-entry effect and is not expected to vary widely between individuals. An interspecies uncertainty factor of 1 was applied because the study was conducted in humans. Time scaling was not performed, because the critical effect (ocular irritation) is a function of direct contact with the bromoacetone vapor and is unlikely to increase with duration of exposure (NRC 2001). However, because of the lack of human data on exposure to bromoacetone longer than a few seconds and because the point of departure was a nominal concentration, a modifying factor of 3 was applied.
When rat irritation data were used to derive AEGL-2 values for bromoacetone, it yielded values essentially identical to the AEGL-3 values calculated from lethality data. Thus, although the concentration-response relationship for bromoacetone is not particularly steep, the AEGL-3 values were divided by 3 to calculate AEGL-2 values.