Impact of Microplastics in Human Health

Because plastics are a multifunctional, resistant, easy-to-process, and affordable material, they play a central role in our daily life. However, their extensive use has become tainted by the continuous rise of plastic pollution worldwide, which generates, after slow photo, chemical, physical, and biological degradation, massive amounts of small-sized microplastics. Their ubiquitous nature in the environment but also in foodstuff and consumer packaged goods has revealed a potential threat to human health. In this chapter, a focus is given on the human gastrointestinal tract, as portal of entry but also first barrier and target for microplastics. We summarize the current state of knowledge on human oral exposure to microplastics and the characteristics of ingested forms (origin, occurrence, size, shape, polymer type, surface properties). Then, we highlight the physicochemical transformations of microplastics during digestion. Afterwards, we detail their potential impact on gut homeostasis disruption, including gut microbiota, mucus and epithelial barriers, considering in vitro and in vivo studies (rodents). Finally, this chapter points out future research directions about microplastics in the field of human intestinal health. Special emphasis is given to the critical need of developing robust in vitro gut models to adequately simulate human digestive physiology for better gut health risk assessment and management of microplastics.