Interconversions and toxicity changes in hexachlorocyclohexane isomers on dispersion in water

Studies on the transformations of hexachlorocyclohexane isomers, alpha-, beta-, gamma- and delta-, in aqueous solution were carried out at 25 +/- 1 degree C over a period of four weeks. Gas liquid chromatographic technique was used for analysis. The results indicated a loss as well as interconversion of all the four isomers with time. The resulting changes in toxicity of the aqueous solution were studied against Drosophila using topical application. Toxicity studies with aqueous solution of technical hexachlorocyclohexane were simultaneously carried out for comparison. Toxicity of the aqueous solutions of alpha-, beta-, and delta- isomers showed an increase while that of the gamma- isomer decreased significantly during the four week experimental period. Aqueous solution of technical HCH was equally toxic as that of the gamma- isomer initially and did not show much decrease in its toxicity at the end. Changes in toxicity of the individual isomer solutions were considered to be due, in part, to interconversions of HCH isomers.