New insights into the reproductive hazards posed by polystyrene nanoplastics

Reproductive toxicity from micro/nanoplastics (MNPLs) is an emerging concern requiring further investigation to close existing knowledge gaps. This study explores the reproductive toxicity of polystyrene nanoplastics (PSNPLs) using Drosophila as an in vivo model. Males and females were exposed to PSNPLs (100 and 500 µg/mL) for one/two weeks. Confocal and transmission electron microscopy revealed widespread distribution of PSNPLs across various tissues, including ovaries, testes, and gametes (ova and sperm). Structural damage, such as hole formation in the seminiferous tubules and ovarian atrophy, was observed following exposure. The physical presence of PSNPLs in reproductive organs disrupted reproductive outcomes, particularly in matings between exposed males and females. Key impairments included reduced fecundity, lower fertility, and a skewed sex ratio, especially after one week of exposure, with minimal effects after two weeks. Significant disruptions in the expression of reproductive and developmental genes were observed in both sexes, with males exhibiting greater sensitivity to PSNPLs, regardless of exposure concentration or duration. These findings provide critical insights into the reproductive toxicity of PSNPLs, underscoring both physical disruptions in reproductive tissues and molecular alterations. This highlights the potential for MNPLs to cause hidden reproductive damage and emphasizes the sex-dependent nature of these toxic effects.