Avaliação toxicológica com microcrustáceo Daphnia magna da qualidade de água de abastecimento público fortificada com agrotóxicos por meio do delineamento composto central rotacional

Abstract

The intensive use of pesticides has demonstrated the potential risks that these substances cause to the environment and humans, as these compounds do not only reach the target. Among the most used pesticides in Brazil, glyphosate and 2.4-D classified as medium toxic and extremely toxic, respectively, have been found in soils and water, causing contamination of the environment and humans. In this sense, the objective of this work was to fortify a sample of groundwater used for public supply of a municipality in the Missions Region of the state of Rio Grande do Sul, with the glyphosate and 2.4-D pesticides, aiming to identify the acute and genotoxicity that these chemical compounds cause when combined in the same sample. For this, a sample of groundwater used for public supply was analyzed, and its quality was evaluated in relation to the physicochemical and microbiological parameters, namely, absorbance (λ – 254 nm), electrical conductivity (µS cm-1), apparent color (uC), hardness (mg CaCO3 L-1), fluoride (mg L-1), dissolved oxygen (mg L-1), hydrogen potential, temperature (° C), turbidity (uT), total coliforms and Escherichia coli, Then the detection and quantification of the pesticides was performed, and then the comparison between the results obtained and the values established in the Consolidation Ordinance nº 5/2017 of the Ministry of Health and the Ordinance nº 320/2014 of the Secretary of State for Health of Rio Grande Do Sul. For the acute toxicity test, the cultivation of the micro crustacean Daphnia magna was performed and for the genotoxicity test the bioindicator Allium cepa was used, the water sample was fortified with the pesticides in conception defined in the central rotational composite design, totaling 12 experiments. The results indicated fluoride, Escherichia coli and total coliforms values in dissonance with the established in Consolidation Ordinance nº 5/2017. Regarding pesticides, the presence of atrazine, azoxystrobin, clomazone, fipronil, tebuconazole and trifloxystrobin were identified, and fipronil was higher than the maximum allowed in Ordinance nº 320/2014 of the Secretary of State of Rio Grande Do The acute toxicity test with Daphnia magna indicated that the herbicide 2.4-D has higher toxicity when compared to glyphosate toxicity, corroborating the maximum allowed value (VMP) in Consolidation Ordinance nº 5/2017, which is lower. VMP for glyphosate. While in the genotoxicity test it was possible to conclude that pesticides interfere with a 95 % significance level in the cell division process. Finally, it is concluded that the combination of pesticides in the same sample of groundwater used for public supply causes damage to the Daphnia magna microcrustacean, interferes with the processes of celldivision and consequently causes damage to human health and the environment due to the effects. toxic and genotoxic effects of these chemical compounds.