The toxicology and metabolism of chlorothalonil in fish. 3. Metabolism, enzymatics and detoxication in Salmo spp. and Galaxias spp.

Hepatic glutathione S-transferase (GST) activity towards chlorothalonil, tetrachloro-isophthalonitrile (TCIN), was established for the five fish species: Salmo gairdneri, S. trutta, Galaxias maculatus, G. truttaceus and G. auratus . Low level exposure to TCIN was found to induce higher GST activity in G. maculatus, G. truttaceus and S. gairdneri . Significant decreases occurred in liver thiol levels of fish when exposed to varying concentrations of TCIN for 96 h without feeding. Liver GSH levels increased in S. gairdneri exposed to 10 mu g/l over 96 h with feeding. A marked increase in GST activity was observed during 96 h exposure to 10 mu g/l. No significant changes in the activity of glyceraldehyde 3-phosphate dehydrogenase (GAPDH) were observed during exposure to 10 mu g/l TCIN in vivo. A transient decrease in activity was observed during exposure to 30 mu g/l TCIN.