Health impacts of microplastic and nanoplastic exposure.

As evidence demonstrating the presence of micro- and nanoplastics (MNPs) in the human body accumulates, so do concerns about their potential health impacts. Multiple factors determine the properties and behavior of MNPs-including polymer type, size, shape and the presence of a biocorona, among others-which place high demands on analytical methodology and tools for assessment of potential adverse health effects. Experimental models have shown that MNPs can cross cell barriers in the human lung and intestine and reach systemic circulation and subsequently tissues such as reproductive organs, placenta and brain. Early clinical findings indicate that MNPs may be associated with adverse health outcomes, including immune modulation, reproductive effects and cardiovascular effects. However, these studies typically suffer from low patient numbers and inadequate MNP exposure assessment, which precludes adequate risk assessment. Still, outcomes from animal and cell-based analyses generally support the preliminary clinical findings. To conduct more robust human studies, maturation of methods for exposure and effect assessment are crucial. Addressing these challenges will improve scientific research on the health impact of MNPs, which is urgently needed.