Effects of the emulsifiable herbicide Dicamba on amphibian tadpoles: an underestimated toxicity risk?

The effects of exposure to the herbicide Dicamba (DIC) on tadpoles two amphibian species, Scinax nasicus and Elachistocleis bicolor, were assessed. Mortality biochemical sublethal evaluated using acetylcholinesterase (AChE), glutathione S-transferase (GST), reductase (GR), aspartate aminotransferase (AST), alanine (ALT) activities thyroid hormone (T4) levels. LC50 value at 48h was 0.859 mg L?1 for S. 0.221 E. bicolor tadpoles. After DIC concentrations 48 h, GST activity increased in but significantly decreased with respect controls. GR only all tested concentrations. AChE inhibited both h. also caused significant changes transamination, as evidenced by an increase AST ALT species. T4 levels higher DIC-treated species than DIC-induced alterations system enzymes transaminases indicate lesions liver tissues cellular function. Moreover, observed inhibition could lead accumulation acetylcholine, excessively stimulating postsynaptic receptors, may overactive thyroid. commercial formulation showed a high biotoxicity native after short-term exposure, controversially differing from toxicity level indicated official fact sheet data. This highlights need urgent re-categorization reevaluation