DEGRADATION OF DIAZINON BY SODIUM-HYPOCHLORITE - CHEMISTRY AND AQUATIC TOXICITY

The insecticide diazinon is rapidly degraded by sodium hypochlorite between pH 8 and 10. The sequence of reactions was determined and the 2 principal end products of the reaction were identified as acetic acid and isobutyramidinium trichloroacetate. Treatment with hypochlorite reduced the acute toxicity of diazinon dust formulations to bluegill [Lepomis macrochirus] by at least 3700-fold. Bioassay data indicated that a diazinon emulsifiable concentrate formulation retained considerable toxicity after treatment with sodium hypochlorite. The toxic components of the emulsifiable concentrate reaction mixture were identified as the heavy aromatic naphtha constituent of the formulation and the chlorinated aromatic hydrocarbons produced by the hypochlorite reaction. These components were almost as toxic as the diazinon formulation. A model approach emphasizing the need for bioassay data in development of chemical disposal systems is proposed and discussed.