Long-term dietary study and development of no-observed-effect level (NOEL) of technical HCH to rats

Daily feeding of technical hexachlorocyclohexane (HCH) (0.5, 5, 25, 250, and 500 mg/kg diet/d) for a period of 360 d to male rats elicited a dose-dependent toxicity, while the dose of technical HCH (0.5 mg/kg diet/d) did not produce signs of intoxication, mortality, organ body weight ratio, enzymatic, and pathomorphological changes. Other doses (5, 25, 250, and 500 mg/kg diet/d) produced significant changes in one or the other parameters studied. Based on this study, it may be suggested that the lowest dose of technical HCH (0.5 mg/kg diet/d) could be considered as the no-observed-effect level in experimental rats.