Toxicological assessment & risk evaluation of pesticides and their mixtures through C. elegans & RISK21: A risk-based approach for sustainable agriculture

Pesticides are extensively used in agriculture to protect crops, but their environmental release, particularly as mixtures, raises concerns about effects on non-target organisms and ecosystem health. This study aimed to evaluate the toxicity of five pesticides used extensively on soybean crops - glyphosate, 2,4-D, paraquat, chlorpyrifos, and lambda-cyhalothrin- and their binary mixtures on the nematode Caenorhabditis elegans , a model organism in toxicology. Locomotion and growth assays were conducted to assess acute and chronic effects, and the RISK21 matrix framework was used to convey environmental risks based on the bioassay results combined with surface water monitoring data and modeled exposure estimates. Our results demonstrate significant reductions in locomotion and body length for all tested pesticides, with synergistic effects observed in binary mixtures. However, the risk-based analysis suggests that the estimated environmental concentrations of these pesticides pose minimal ecological risks. In conclusion, our work highlights the novelty of combining C. elegans -based toxicity assays in a risk-based approach to evaluate pesticide mixtures, offering a practical approach for predicting environmental impacts and promoting sustainable agriculture. • Locomotor activity and growth were affected by commercial formulation of pesticides • The mix of 2,4-D with paraquat synergistically affected the growth of C. elegans • The mix of glyphosate with chlorpyrifos synergistically affected nematode growth • A higher toxicological risk was identified when pesticides were combined