Intergenerational transfer of micro(nano)plastics in different organisms

Micro(nano)plastics (MNPs), widely distributed in the environment, can be ingested and accumulated by various organisms. Recently, the transgenerational transport of MNPs from parental organisms to their offspring has attracted increasing attention. In this review, we summarize the patterns, specific pathways, and related mechanisms of intergenerational transfer of MNPs in plants, non-mammals (zooplankton and fish) and mammals. The knowledge gaps are also discussed. For plant, MNPs can accumulate in fruits and seeds by intercellular and cellular internalization pathways after uptake by roots or leaves. In zooplankton (e.g., Daphnia magna), MNPs are capable of maternal transfer via two different pathways: gut-ovary-egg and brood chamber-embryo. Intergenerational transfer of MNPs in egg-laying fish can occur through direct maternal transfer. However, MNPs may be transported through follicular pseudoplacenta, surface epithelia, and trophotaeniae pathways in ovoviviparous fish. In mammals, the maternal-fetal transport of MNPs primarily occurs through the placenta, amniotic fluid, and breastfeeding. The placental barrier is the main limitation to transfer, and the ability of MNPs to cross this barrier largely depends on the trophoblast cells via internalization and intercellular pathways. Additionally, we discuss the physicochemical properties (e.g., size, shape, and ageing) of MNPs and environmental factors (e.g., salinity, minerals, organic matter) that influence intergenerational transfer. Current challenges regarding the transfer pathways and related mechanisms, as well as future perspectives, are also addressed. This review provides valuable information for assessing the fate of MNPs in organisms and potential risks to population, community, ecosystems, and human health.