Previous findings from our laboratory suggested a possible interaction of
atrazine,
bentazon and
molinate with other environmental and/or occupational
poisons. The aim of this research was to obtain further toxicological information by using
phenobarbital-induced rats and to characterize the effects of these
herbicides on the hepatic microsomal metabolism of
xenobiotics. Acute experiments have shown that the LD50 is augmented by the
barbiturate pretreatment when
atrazine is used, remains unchanged in the case of
bentazon, but is lowered when
molinate is given. Recrystallized
atrazine, in the absence of the wetting compounds, elicits the same acute toxicity found when animals are challenged with a commercial preparation. No significant sex-related differences have been observed. In long-term treatment with these toxicants,
atrazine shortened the
hexobarbital narcosis, but no effect was observed after administration of either
bentazon or
molinate. Further studies on
hexobarbital sleeping time demonstrated that females are more susceptible than males to the
narcotic effect of this compound. The induction-like effect of
atrazine exposure has been confirmed, mainly in young animals. At the end of the sleeping time, the actual serum concentration of
hexobarbital is practically the same, and is not related to the length of the sleeping time. The absence of behavioral alterations in the open field tests exclude possible neurological effects of the
triazine herbicide. In conclusion, these data demonstrate that
atrazine by itself induces the hepatic pharmacometabolic system, while its metabolites result less toxic than the parent compound. On the contrary, metabolic transformations render the toxic effects of
bentazon more severe.