The toxicology and metabolism of chlorothalonil in fish. 4. Zinc co-exposure and the significance of metallothionein in detoxication in Salmo gairdneri .

Rainbow trout, Salmo gairdneri , were subjected to various regimes of exposure to zinc (0.36 mg/l) and super(14)C-chlorothalonil ( super(14)C-TCIN, 10 mu g/l). Gel column chromatography of hepatic cytosol after exposures showed no binding of super(14)C-TCIN to metallothionein proteins with or without pre-exposure or with coexposure to zinc. super(14)C-TCIN did not induce the production of metallothionein with or without 96 h preexposure to 0.36 mg/l zinc, whereas induction did occur with zinc coexposure over 156 h. super(14)C-TCIN exposure did not affect cytosolic zinc levels, but exposure to zinc did reduce the level of cytosolic super(14)C-TCIN over the observed protein molecular weight range. It appears that metallothionein does not play a significant role in TCIN detoxication at this sublethal exposure level.