Comparative ecotoxicological assessment of nano-formulated and conventional copper-based pesticides on the freshwater snail Planorbarius corneus

Copper (Cu) is extensively used in agriculture, yet its environmental accumulation raises significant ecotoxicological concerns. Nano-formulations have been developed as alternatives allowing to decrease Cu application rates, but their effects on non-target species remain poorly understood, particularly in aquatic ecosystems. This study evaluated the ecotoxic potential of the commercial copper-based nanopesticide, Kocide 3000® in comparison with the conventional formulation Kocide 2000®, using the freshwater gastropod Planorbarius corneus as a model species. A copper salt was also included as a control to specifically assess copper- related toxicity. Juvenile snails were submitted to a 48-hour acute toxicity test. Egg masses (embryos) were exposed to a range of copper concentrations (10-500 µg Cu/L) for 12 days until hatching. Growth, developmental progression, heart rate, and shell size were assessed as multiple endpoints. A recovery assay was conducted to investigate whether the impact of an early exposure was reversible. All three formulations induced measurable adverse developmental effects with increasing copper concentrations. Across all endpoints, nano and conventional formulations induced comparable effects, suggesting minimal nanomaterial-specific impacts and indicating that copper load, primarily drives toxicity under these exposure conditions. Interestingly, recovery potential differed between the copper salt and the commercial formulations since only CuSO₄-exposed embryos showed a return to a developmental state comparable to unexposed individuals after transfer to clean water. This finding highlights the influence of product composition in persistence and recovery dynamics. These results emphasize the importance of evaluating complete pesticide formulations, not just active ingredients in the hazard assessment of agrochemicals.