Integrated assessment of pesticides, inorganic ions, and health risks in drinking water from Missal, a rural agricultural municipality in Southern Brazil.

Missal is a small municipality in Paraná, southern Brazil, with an economy predominantly based on soybean and corn cultivation. This study evaluated the occurrence of pesticides and inorganic ions in nine groundwater-derived drinking water sources and one surface water reference site. A total of 120 water samples were collected monthly over one year and analyzed using chromatographic methods. Results were evaluated according to Brazilian drinking water regulations and compared with international guidelines. Paraquat and parathion, both banned in Brazil, were detected at concentrations of 4.50-93.21 µg L-1 and up to 71.02 µg L-1, respectively. Glyphosate and AMPA were found in 53% and 77% of samples, respectively, while 2,4-D and parathion were present in all samples. Temporal analysis indicated seasonal variation, with significantly higher concentrations during periods of increased precipitation (p < 0.05), with total pesticide concentrations reaching up to 400 µg L-1. These patterns suggest temporal influence associated with agricultural application and rainfall-driven transport. Cytotoxicity and genotoxicity were assessed using the Allium cepa assay, revealing increased mitotic index and chromosomal aberrations at six sampling points. A Hazard Index (HI) greater than 1 was observed at seven points, mainly due to nitrate and parathion, suggesting potential non-carcinogenic health risks. These findings suggest that combined exposure to pesticides and inorganic ions may contribute to non-carcinogenic risk, supporting the relevance of continuous and integrative monitoring.