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.

SUMMARY

Methanesulfonyl chloride is a pale yellow liquid with an unpleasant odor. It is made commercially either by the chlorination of methyl mercaptan or by the sulfochlorination of methane. It is used as an intermediate in the pharmaceutical, photographic, fiber, dye, and agricultural industries. It is also used as a stabilizer, catalyst, curing agent, and chlorinating agent. Methanesulfonyl chloride causes severe ocular, dermal, and mucous membrane irritation. Chlorine gas and sulfur oxides are produced when it is heated until decomposition.

Data were insufficient to derive AEGL-1 values for methanesulfonyl chloride. Therefore, AEGL-1 values are not recommended.

Appropriate chemical-specific data were not available for deriving AEGL-2 values. In the absence of such data, chemicals with a steep concentration-response curve may be derived by dividing AEGL-3 values by 3 (NRC 2001). A steep concentration-response curve has been demonstrated for methanesulfonyl chloride; mortality in rats exposed to it for 4 h was 10% at 20 ppm and 90% at 28 ppm (Pennwalt Corporation 1987).

A 4-h rat BMCL05 (benchmark concentration, 95% lower confidence limit with 5% response) of 15.5 ppm (Pennwalt Corporation 1987) was used as the point of departure for AEGL-3 values. Values were time scaled using the equation Cn × t = k, where n ranges from 0.8 to 3.5 (ten Berge et al. 1986). An empirical value for n was sought by analyzing lethality data in rats exposed for 1-6 h by log probit analysis (see Appendix E). However, the data and modeling results were considered inadequate to define an empirical value of n, but



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