Translocation, distribution, and environmental degradation of hexachlorophene in tomatoes

Abstract

The translocation, distribution, metabolism and environmental degradation of hexachlorophene were investigated in tomato plants (Lycopersicon esculentum Mill cv. beefsteak). All plants were grown under standardized conditions and treated with leaf-applied¹⁴C-ring-labeled hexachlorophene (HCP). Treatment time ranged from 0 to 70 days. Autoradiographic analyses were performed on all plants. Selected plant tissues were extracted and chromatographed, using thin layer (TLC) and gas liquid chromatography (GLC).

Hexachlorophene was not translocated from the plant leaves. No metabolites of hexachlorophene were found. A slight, but statistically nonsignificant, amount of HCP was lost from the leaves and the inert controls.

At the end of the 70-day treatment, based on TLC and regression analysis of thin layer chromatographic plates, averages of 89.5% and 75.9% of the applied HPC remained unaltered on the treated plants and controls, respectively. This indicated that 10.5% and 24.1%, respectively, of the original HCP had been altered. Differences between the treatments and controls were statistically significant after 28 days of exposure. Further analyses of the above data, using gas chromatographic methods, showed that as many as 14 peaks were found in the treated samples and the controls, including the parent material.

Ultraviolet photolysis seemed to be the mechanism responsible for alteration of the hexachlorophene. Three extracted chlorinated compounds have been identified by GC-mass spectral (MS) analysis including 2,2′-dihydroxy-3,5′, 6,6′-tetrachlorodiphenylmethane, 2,2′-dihydroxy-3,5,5′,6,6′-pentachlorodiphenylmethane, and 2,2′-dihydroxy-3,3′,5,5′,6,6′-hexachlorodiphenylmethane (parent HCP). Eleven other electrophylic compounds have been found in various treated plant or control extracts. Further analyses will be necessary to verify the identification of the other degradation products.