Postnatal development outcomes in mice after gestational exposure to polystyrene nanoplastics.

Nanoplastics (< 1 μm) are contaminants of emerging concern. Humans are daily exposed to these particles, and they have even been found in placental tissue, raising concern regarding gestational exposure. Thus, the present work aimed to investigate the effects of gestational exposure to polystyrene nanoplastics (PS-NP) and postnatal development outcomes. Female C57BL/6 mice (n = 9) where mated with male BALB/c mice (n = 9). Dams were separated into two experimental groups: PS-NP (n = 4), which was treated by gavage with 0.15 mg/d (7.5 mg/kg/d) of PS-NP (500 nm) diluted in distilled water (vehicle), and Control (n = 5), which was treated by gavage with distilled water between gestational days 5 and 19. The offspring were evaluated for developmental milestones between postnatal days (PND) 1 and 21. Males were euthanized on PND 42 and 70 to assess organ weights, testes and epididymides development, and sperm quality. In the PS-NP group, females had increased anogenital distance (AGD), while males showed a tendency toward reduced AGD and delayed cliff-avoidance reflex. On PND 42, males had significantly lower brain and kidney weights. Considering the small sample size, these preliminary findings highlight that even low doses of PS-NP during pregnancy may affect early development, raising concerns regarding human health and fertility.