ACUTE TOXICITY OF HERBICIDES DIURON AND HEXAZINONE TO Danio rerio

The objective of this study was to evaluate the toxicity of a commercial herbicide extensively used in sugarcane cultivation, composed of diuron, hexazinone and inert ingredients using Danio rerio as test organism. Laboratory tests were performed according to the recommendations of the ABNT 15088 (2004) and USEPA (2002) standards. The water control parameters were pH, total water hardness, electrical conductivity, dissolved oxygen and temperature, swimming activity and mortality of the test organism. The lethal concentration (LC50) of the commercial herbicide for Danio rerio was of 581.50mg.L-1. Significant behavioral changes were observed at concentrations starting from 50 mg.L-1 of the commercial herbicide, causing hypoactivity of swimming movements in over 50% of the test organisms. To evaluate the toxicity of the inert ingredients, which account for 40% p/p of the herbicide's composition, the compounds hexazinone and diuron were tested separately. At the studied concentrations, hexazinone and diuron did not cause mortality or altered swimming movements. It was concluded that the inert ingredients in the composition of the commercial herbicide were the major cause for acute toxicity to Danio rerio.