DETECTION OF PESTICIDES IN WATER BY BIOCHEMICAL ASSAY

Abstract

The wide-spread use of organic pest icides, their potential as water con taminants, and their high toxicity have necessitated the development of tech niques for determining their presence in water. The initial evaluation of the toxicity of these compounds to aquatic organisms, particularly fish, followed the standard technique for bioassay that was proposed in 1951 and gen erally adopted for the evaluation of toxic substances in water (1). These procedures provided a systematic ap proach to the establishment of the comparative toxic potential of these pesticides in surface waters. How ever, the significance of pesticides in water is not only the consideration of direct toxic effects but, of equal im portance, also involves consideration of chronic effects. The two major classes of organic pesticides, chlorinated hydrocarbons and organic phosphorous compounds, differ both in their mode of action as well as their chemical behavior in water. Chemical assay of these com pounds in water, at concentrations of 1 mg/1 or lower, has been limited un til very recently by the sensitivity of the analytical procedures. It was not always possible to chemically detect the presence of the compounds at the levels which were obviously producing physiological reactions in exposed