TOXICIDAD AGUDA DEL MALATION 500® Y TYSON 4E® EN Capitella sp.

Abstract

The toxicity of Malation 500® and Tyson 4E®, whose active ingredients are malathion and chlorpyrifos ethyl, respectively, was experimentally determined using as test organism Capitella sp. collected in the Chetumal Bay and acclimated on lab. To do that, 48 h static toxicity bioassays were done using five nominal concentrations distributed in a logarithmic scale, a blank and three replicates for each bioassay chamber. Ten organisms were exposed to each concentration in crystallizer dishes with a sediment layer, saline solution and their respective volume of pesticide. Mortality was registered and median lethal concentrations (LC50) were determined through the Probit analysis with 95 % confident intervals. The LC50 were 27.79 ± 2.67 mg/L for Malation 500® and 7.46 ± 1.59 mg/L for Tyson 4E®, therefore this last one is more toxic. ANDEVA showed significant differences in the tested concentrations (p < 0.05). Malation 500® was classified as slightly toxic and Tyson 4E® as moderately toxic for Capitella sp. Both risk quotients of the pesticides (RQ < 1) indicate that the ecological risk is negligible.