Toxicological effects of polypropylene microplastics and co-exposure with arsenic in <i>Drosophila melanogaster</i>

Microplastics (MPs) are particles smaller than 5 mm that, due to their physicochemical properties, can act as carriers for contaminants such as heavy metals. In this study, we evaluated the toxicological effects of polypropylene microplastics (PP-MPs) and their co-exposure with dimethylarsinic acid (DMA) in the Drosophila melanogaster model. Third-instar larvae were exposed to the following experimental groups: negative control, positive control (0.02% H2O2), cosolvent control (ethanol, 6.94% final concentration), PP-MPs (0.01 g/mL), DMA (0.5 mM), and the co-exposure group (PP-MPs + DMA). Larval-to-adult viability, morphology, tissue damage, and fecundity were assessed. PP-MPs alone did not significantly affect larval-to-adult viability, the incidence of morphological abnormalities, or fecundity; however, evidence of tissue damage was observed. In contrast, co-exposure suggested an antagonistic effect on larval-to-adult viability and tissue damage, while indicating a synergistic effect on fecundity and the incidence of abnormalities. These findings contribute to a better understanding of the biological effects associated with co-exposure to microplastics and arsenic in an in vivo model.