Occurrence of Some Chlorinated Aliphatic Hydrocarbons in the Environment

Abstract

THE total world production of chlorinated aliphatic hydrocarbons probably exceeds 3 × 10⁶ ton yr⁻¹ (ref. 1). Some of the compounds concerned are used chiefly as intermediates in the chemical industry (for example, in the manufacture of polyvinylchloride, aerosol propellants and refrigerants). But others are employed principally as solvents, particularly for degreasing and dry-cleaning. By contrast with the compounds used as intermediates, for which losses to the environment are unlikely to exceed 1–2%, most of those used as solvents will eventually be lost, chiefly by evaporation but also in effluents. Their loss in the United States alone has been estimated to be ∼2 × 10⁵ ton yr⁻¹ (ref. 2). Most of the commercially important chlorinated aliphatic hydrocarbons are comparatively stable compounds, and are likely to have reasonably long lifetimes in the atmosphere and aquatic environment. It is likely therefore that the atmosphere and surface waters would contain significant concentrations of them (particularly those used as solvents). At present there seems to be no information available about the levels of these compounds in the natural reservoirs, nor about the extent to which they are concentrated by aquatic organisms. A project has been initiated recently in these laboratories to examine the environmental distribution of the aliphatic chlorocompounds. We present here some preliminary data for air and natural waters.