Cytogenotoxicity of soil contaminated with an atrazine-based herbicide under laboratory conditions: bioassays with Allium cepa

Atrazine is a widely used herbicide for weed control in crops such as corn, sugarcane, and sorghum. However, it can have adverse effects on non-target organisms. This study aimed to evaluate the cytogenotoxic effects of a Red-Yellow Latosol contaminated with atrazine under laboratory conditions. Concentrations exceeding the recommended field doses (2 mg/kg to 1024 mg/kg) were tested, simulating excessive herbicide use and contamination from effluent disposal, such as wash water from spraying tanks and improper disposal of pesticide containers — major point sources of agricultural soil contamination. Allium cepa bioassays were conducted. Soil contaminated with 16, 32, 64, 128, 256, and 512 mg/kg of atrazine reduced cell viability. Only the 8 mg/kg concentration significantly decreased the mitotic index. Conversely, except for the 32 and 128 mg/kg treatments, all other concentrations increased the frequency of aberrant cells compared to the control soil. Atrazine is poorly adsorbed in soils with low clay content and moderate-to-low organic matter content, which increases its bioavailability and, consequently, its cytogenotoxic potential. Therefore, implementing mechanisms capable of retaining and treating effluents with high atrazine concentrations before soil disposal is strongly recommended.