Gender effects of nanoplastics and emerging contaminants mixtures in Mytilus galloprovincialis

The reproduction of mussels occurs within the water column, and if gametogenesis is successful, gametes are exposed to the surrounding contaminants. Nanoplastics and other emerging contaminants have been gaining vast attention; however, their effects on the reproductive tissues of mussels with sex differentiation are scarce. Here, the effects of polystyrene nanoparticles (50 nm; 10 µg/L), the cytotoxic drug 5-fluorouracil (10 ng/L), and a mixture of the two were evaluated in the gonads of Mytilus galloprovincialis after a 21-day exposure for a multi-biomarker assessment, and after 28 days for the accumulation of nanoplastics. The effects on the activity of superoxide dismutase, catalase, glutathione-S-transferase, and lipid peroxidation were evaluated. Moreover, synergistic and antagonistic interactions in the mixture were calculated. A weight of evidence model was also used to elaborate on the hazardous level of biomarker results relative to polystyrene nanoparticles alone and in the mixture. The accumulation of nanoplastics appeared gender and time-specific, with females mostly compromised. According to the data set, a synergistic interaction between the cytotoxic drug and the nanoplastics makes the combination far more dangerous than individual stressors. The Weight Of Evidence model also confirms that females are more compromised at chronic exposure times than males. This study shows that the uptake, fate, and impact of emerging contaminants of concern can be significantly influenced by sex.