Persistent Polyhalogenated Compounds: Biochemistry, Toxicology, Medical Applications, and Associated Environmental Issues

Abstract

This chapter will focus on several classes of halogenated compounds that have had widespread practical applications in industry and commerce. Because many of these compounds are chemically and thermally very stable, their extensive use has evoked serious concerns over potential longterm harmful effects to the environment. Indeed, many of these compounds have proven to be quite toxic, and environmental concerns are increased by their bioaccumulation in the food chain. Research designed to elucidate mechanisms of toxicity has helped define environmental issues and has produced significant biochemical data not only on the toxicology of the compounds of concern, but also on cellular mechanisms of the organisms involved, including humans. The environmental impact of certain halogenated compounds makes this topic a matter of extreme relevance, and inclusion of this subject in this volume clearly is appropriate. Biochemistry, toxicity, and potential environmental impact of several classes of halogenated insecticides will be considered first. This will be followed by a review of the problems associated with the toxicity of polyhalogenated hydrocarbons and related phenols, dioxins, and dibenzofurans. The development of halogenated volatile anesthetics and the use of perfluorinated aliphatic hydrocarbons as artificial oxygen carriers will be reviewed briefly. The biochemistry of simple halogenated aliphatic compounds, such as chloroform and carbon tetrachloride, is related in large part to metabolic activation to toxic species and will be discussed in Chapter 9.