Human biomonitoring of microplastics and health implications: A review

BACKGROUND: Microplastics (MPs) are plastic particles (<5 mm) ubiquitous in water, soil, and air, indicating that humans can be exposed to MPs through ingestion of water and food, and inhalation. OBJECTIVE: This review provides an overview of the current human biomonitoring data available to evaluate human exposure and health impact of MPs. METHOD: We compiled 91 relevant studies on MPs in human matrices and MPs toxicological endpoints to provide evidence on MPs distribution in the different tissues and the implications this can have from a health perspective. RESULTS: Human exposure to MPs has been corroborated by the detection of MPs in different human biological samples including blood, urine, stool, lung tissue, breast milk, semen and placenta. Although humans have clearance mechanisms protecting them from potentially harmful substances, health risks associated to MPs exposure include the onset of inflammation, oxidative stress, and DNA damage, potentially leading to cardiovascular and respiratory diseases, as well as cancer, as suggested by in vitro and in vivo studies. CONCLUSION: Based on compiled data, MPs have been recurrently identified in different human tissues and fluids, suggesting that humans are exposed to MPs through inhalation and ingestion. Despite differences in MPs concentrations appear in exposed and non-exposed people, accumulation and distribution pathways and potential human health hazards is still at an infant stage. Human biomonitoring data enables the assessment of human exposure to MPs and associated risks, and this information can contribute to draw management actions and guidelines to minimize MP release to the environment, and thus, reduce human uptake.