Avaliação da toxicidade de herbicidas usados emcana-de-açúcar para o Paulistinha (Danio rerio) / Toxicity evaluation of herbicides used in sugarcane crops toZebrafish (Danio rerio)

Na natureza, os organismos são constantemente expostos a mais de um agente tóxico e, apesar do fenômeno de interaçõesquímicas ser conhecido há tempos, são poucos os estudos realizados que privilegiam a observação dos efeitosdecorrentes da exposição a duas ou mais substâncias. O objetivo deste trabalho foi avaliar o efeito combinado damistura dos herbicidas Gesapax 500® (ametrina 500 g/L) e Velpar K® (diuron 468 g/kg + hexazinone 132 g/kg) sobreo paulistinha (Danio rerio). O ensaio foi baseado no teste FET da OECD, com duração de 96 horas. As concentraçõestestadas foram 0, 21,22, 29,52, 41,08, 57,17 e 79,56 mg/L de Gesapax 500 vs. 0, 15,21, 21,17, 29,46, 40,99 e 57,04mg/L de Velpar K. Os testes foram conduzidos em triplicata e avaliados diariamente. As CL50-96h determinadas foram41,705 ± 8,373 mg/L para o Gesapax 500 e 55,460 ± 20,826 mg/L para o Velpar K. O modelo da mistura que melhordescreve a relação entre os dois componentes é a ação independente, sendo a toxicidade dose-dependente, ou seja,em baixas doses ocorre antagonismo e, em altas doses, sinergismo. Os endpoints edemas, atraso no desenvolvimentoembrionário (delay) e na absorção do saco vitelínico e diminuição na frequência de cardíaca foram observados apartir das concentrações mais baixas da mistura. Pelos dados obtidos, concluiu-se que a mistura de Gesapax 500 eVelpar K é medianamente tóxica para o paulistinha e que os endpoints avaliados foram úteis na determinação de suatoxicidade.

In nature, organisms are constantly exposed to more than one toxic agent, and although the phenomenon of chemical interactionsare known for some time, there are few previous studies that emphasize observation of the effects resulting fromexposure to two or more substances. The aim of this study was to evaluate the combined effect of the mixture of herbicideGesapax 500® (ametrina 500 g/L) and Velpar K® (diuron 468 g/kg + hexazinone 132 g/kg) on zebrafish (Danio rerio). The testwas based on the Fish Embryo Toxicity (FET) from OECD, lasting 96 hours. The concentrations tested were: 0, 21.22, 29.52,41.08, 57.17 and 79.56 mg/L Gesapax 500 vs. 0, 15.21, 21.17, 29.46, 40.99 and 57.04 mg/L Velpar K. Tests were conductedin triplicate and evaluated daily. LC50-96h was determined to 41.705 ± 8.373 mg/L to Gesapax 500 and 55.460 ± 20.826 mg/Lto Velpar K. The mixture model that best describes the relationship between the two components is independent action andtoxicity of the mixture is dose-dependent, occurring antagonism at low doses and synergism at high doses. The endpointsedema, delay in general development and in yolk sac absorption and decrease in frequency of heart-beat rate were observedfrom the lower concentrations of the mixture. From the data obtained, it is concluded that the mixture of Velpar K and Gesapax500 is moderately toxic to zebrafish and that the endpoints evaluated were useful in determining its toxicity.

In Vitro Cytotoxic Effect of Glyphosate Mixture Containing Surfactants

We investigated whether glyphosate influences the cellular toxicity of the surfactants TN-20 and LN-10 on the mouse fibroblast-like cells, alveolar epithelial cells, and a heart cell line. The cytotoxicity of TN-20 and LN-10 (0.4-100 microM), in the presence or absence of glyphosate was determined by assessing membrane integrity. TN-20 toxicity was significantly lower in the presence of 50 microM glyphosate for the fibroblast-like cell (6.25 microM; 3.9% +/- 3.4% vs -4.8% +/- 0.7%), for the alveolar cells (0.78 microM; 5.7% +/- 0.9% vs 0.1% +/- 0.6%), and for the heart cell line (25.0 microM; 7.9% +/- 3.0% vs 19.4% +/- 0.7%) compared to that of TN-20 alone. The cellular toxicity of LN-10 towards the fibroblast-like cells was found to be increased in the presence of 50 microM glyphosate when LN-10 concentrations of 50 microM (31.3% +/- 3.9% vs 19.2% +/- 0.9%) and 100 microM (62.1% +/- 3.4% vs 39.0% +/- 0.7%) were compared to that of LN-10 alone. These results suggest that the mixture toxicity may be a factor in glyphosate-surfactant toxicity in patients with acute glyphosate herbicide intoxication.