Quantification and visualization of micro- and nano-plastics transfer from maternal to fetal: A rat model study

Micro- and nano-plastics (MNPs) are emerging pollutants, with growing evidence suggesting the presence of MNPs in human tissues. However, there is a notable lack of quantitative data regarding the maternal-embryonic transfer of MNPs. In this study, rats were utilized as model animals and were orally exposed to europium-labeled nanoplastics (Eu-NPs, 0.2 μm) and microplastics (Eu-MPs, 2 μm) over 18 days, from gestation day 0.5 to day 18.5. High-angle annular dark-field scanning transmission electron microscopy and inductively coupled plasma mass spectrometry were employed to qualitatively and quantitatively track the maternal-fetal transfer of MNPs. The results indicate that the transfer of MNPs from the placenta to the fetus exhibits size-dependent. Specifically, the transfer rate from the placenta to fetus reached 0.48 %, significantly higher than that of Eu-MPs. Notably, MNPs underwent deformation and fragmentation during in vivo transfer. The study also demonstrated that MNPs primarily accumulated in the rat decidua, where they compressed capillaries, potentially impairing fetal growth. These findings provide new insights into the maternal-fetal transfer of MNPs and offer a novel perspective for further investigating the impact of MNPs on maternal and fetal health.