Potential Human Health Impacts of Microplastics and Associated Chemicals

Microplastic (MP) pollution is an emerging environmental threat with the discovery of positive correlations between human tissue lesions and detected MP levels. Its potential impact on human health has attracted increasing attention. Recently, especially in the last 5 years, there has been an explosion in the number of MP-related articles. This chapter reviews human exposure pathways to MPs (e.g., ingestion, inhalation, dermal contact, and infusion/surgical contact). The accumulations of MPs in human tissues, including the intestine, nasal cavity and lung, blood, semen and testes, placenta, and feces, are also further discussed. Moreover, the toxicological effects of MPs on human tissues are summarized based on human cell and mammalian research. Limited studies indicate that MPs and their associated chemicals may induce oxidative stress/cytotoxicity, disrupt energy homeostasis/metabolism, impair immune function, induce neurotoxicity, and act as vectors of microbes/potentially toxic chemicals. However, there is still insufficient direct evidence linking MPs and their associated chemicals to human health under actual exposure scenarios, and future studies are needed to provide quantitative support for evaluating the risks of MPs to human health.