Pathways of human exposure to microplastics, and estimation of the total burden

Plastic production is continuously growing and their wastes contaminate practically all environmental niches. In the environment, large plastics undergo continuous degradation processes generating a broad amount of microplastics and nanoplastics (MNPLs) that spread through air, land, and seas. Thus, humans suffer chronic exposures to MNPLs through different pathways: ingestion, inhalation, and dermal contact. Here, we have reviewed the recently published data regarding human exposure to MNPLs. The total load of plastic particles that humans are exposed to has been estimated based on these newly reported studies. This analysis of novel literature shows that despite ingestion is the most studied route of exposure, other routes of contact with MNPLs should not be underestimated. At the same time, gaps regarding the investigation of human exposures to environmental MNPLs have been detected, as well as the lack of robust and standardized protocols, operating procedures, and methodologies to detect/quantify MNPL in human/biological matrices.

Automated summary

The continuous growth of plastic production results in contamination of environmental niches by plastic waste. Degradation of large plastics leads to the production of microplastics and nanoplastics that spread through various pathways, causing chronic human exposure. Despite ingestion being the most studied exposure route, other contact pathways should not be underestimated. Gaps in the investigation of human exposure to environmental microplastics and a lack of standardized protocols for detection and quantification have been identified.