Polystyrene microplastics exacerbate acetochlor-induced reproductive toxicity and transgenerational effects in zebrafish.

Microplastic (MPs) can adsorb co-existing pollutants, and alter their behavior and toxicity. Meanwhile, amide herbicides like acetochlor (ACT) are widely used in agriculture, with potential endocrine-disrupting effects that raise ecological concerns. The aim of this research was to examine the effects of MPs on the reproductive endocrine disruption caused by ACT and the effects of maternal transmission. Zebrafish were employed in this study to assess the reproductive toxicity of ACT alone and in combination with polystyrene microplastics (PS-MPs) of different sizes (200 nm and 2 μm) and concentrations (0.1 and 1 mg/L) over a 63-day exposure experiment. The results indicated that ACT was concentrated in zebrafish tissues in the order: intestine > liver > gill > brain > gonad > muscle. PS-MPs increased ACT bioaccumulation, worsened gonadal damage, led to abnormalities in hormone levels, and caused disruptions in HPG axis gene expression, further exacerbating the reproductive toxicity. Maternal transfer of ACT affected offspring growth, thyroid function, and HPT axis gene expression, with nanoplastics (NPS) amplifying these adverse effects. This study offers crucial insights into the ecological hazards posed by ACT and PS-MPs, emphasizing the increased toxicity due to PS-MPs.