Carcinogenic Risk Assessment for Occupational Exposure to Monohalomethanes

摘要

There are four monohalomethanes whose common names are methyl fluoride, methyl chloride, methyl bromide, and methyl iodide. Only the last three compounds are of substantial interest; methyl fluoride has little commercial use and will not be considered further. The monohalomethanes are principally used in industry as methylating agents, although they are also used as fumigants and other applications. In the past, the most important factors considered in designing procedures for the safe handling of these compounds have been their neurotoxicity and other acute effects. Because these compounds are alkylating agents, concern has arisen over their potential carcinogenicity. Several studies have suggested that the monohalomethanes are mutagenic in appropriate test systems, and three studies reported in recent years have suggested that methyl chloride and methyl iodide may be carcinogenic in experimental animals. This report presents a critical review of these and other studies and assesses the carcinogenic potential of each of the three monohalomethanes. It also presents a quantitative assessment of the carcinogenic risks that might be incurred by workers exposed to these compounds in the workplace under a wide range of exposure conditions.