Estimación De La Toxicidad Combinada De Mezclas De Furadán 4F® Y Monofos® Sobre Oncorhynchus Mykiss (walbaum, 1792)

The aim of present study was to evaluate the ecotoxicological effect of Furadán 4F® (active ingredient (a.i.) carbofuran) and Monofos® (a.i. metamidophos) in heterotoxic and equitoxic mixtures on trout larvaes Oncorhynchus mykiss and, with these results, to evaluate aquatic environmental risk of both insecticides. Mortalities were evaluated from 24 to 96 hours of exposure and joint toxicity was estimated through the calculation of toxic units (TU). For heterotoxic mixtures exposure, LC50 (96 hours) of Monofos® decreased with the increase of two fixed and constant concentrations of Furadán 4F® (251 and 502 μg.L-1 equivalent of a.i. carbofuran), exhibiting synergic toxicity. The same behavior was observed for the LC50 (96 hours) exposure to Furadán 4F® at five constant and fixed concentrations for Monofos® (1.42; 2.85; 5.70; 11.41 and 22.82 mg.L-1 equivalent of a.i. metamidophos), which also showed synergic toxicity. TU varied from 0.97 to 1.02 for equitoxic mixtures. Results indicate that Furadán 4F® and Monitor® exhibit a synergic or partial additive toxicity whenever at equitoxic concentrations.