Agrotóxicos em águas de abastecimento: um diagnóstico sistematizado da porção mineira da Bacia do rio São Francisco

Abstract

Considering the impacts resulting from the development of agricultural activities, pesticides represent a group of contaminants that can negatively affect aquatic life, ecosystems, and soil, in addition to causing direct effects on human health. Regarding the alteration of water quality in water supply sources, drinking water is a potential source of exposure. This study aimed to build a systematic diagnosis of the pesticide presence in water sources in Minas Gerais, with emphasis on the Minas Gerais portion of the São Francisco River Basin. From the analysis of the water supply quality data present in SISAGUA from 2015 to 2020, it was possible to obtain an overview of the risks involved in the agricultural activities developed. The monitoring carried out by the control showed the violation of 19 of the 27 parameters established by Ordinance GM/MS No. 2914/2011 for the presence of pesticides in water for human consumption. Of the 19 parameters violated, 5 represented approximately 50% of the analyses above the VMP quantified in the state: aldrin+dieldrin (n=58), aldicarb+aldicarbesulfone+aldicarbesulfoxide (n=28), DDT+DDD+DDE (n=27) and lindane (n=25), all with prohibited use and commercialization in the country. In the surveillance analyses, compounds that were not included in the regulations in force during the period evaluated (Ordinance GM/MS No. 2914/011) were detected: epoxiconazole, thiamethoxam, clothianidin, and imidacloprid. Given the supply water monitoring data from the São Francisco River basin, ten pesticides were identified above the maximum level established by the GM/MS Ordinance No. 2914/2011, being 7 insecticides and 3 herbicides. A correlation was observed between the main uses of these substances identified above the MLP and the most significant crops in the Upper São Francisco (coffee, banana, corn, sugarcane, beans, and soybeans) area. Regarding the concentration of pesticide residues in water, the data suggest that despite the high values of Log Kow, precipitation can be a relevant factor in the transport of these substances to the springs supplying the basin. Considering the QR values referring to the risk assessment of this work for the ten pesticides identified above the MLP, the Brazilian legislation would not protect the aquatic ecosystem in the São Francisco River basin. It was also found that of the 10 compounds studied, 7 pose a potential risk of surface water contamination by runoff, associated with sediment or dissolved in water, according to the Goss criteria. According to the Gus criteria, only atrazine was classified as potentially contaminating groundwater. In this context, the study pointed out possible negative impacts of agricultural activities on water resources, aquatic biota, and humans. It highlights the need for the formulation and implementation of public policies to rationalize the use of pesticides in the basin and in the state as a whole. In addition, policies should be developed to promote good agricultural practices and encourage research on the effects of these compounds in different environmental compartments.