Microplastics and forever chemicals in food webs: Should we be concerned?

Abstract

Micro- and nanoplastics (MNPs) and persistent organic pollutants, including per- and polyfluoroalkyl substances, are frequently reported food web contaminants. This review explores the literature on the toxicology of MNPs and their role as secondary vectors of persistent chemical pollutants, focusing on the distinction between the hazard of polymer matrices and that of associated organic pollutants. While MNPs may facilitate the ingestion of phthalates and other organic pollutants, the latter normally are ingested in concentrations several orders of magnitude higher than those carried by plastics. MNPs may be retained within the body beyond the normal gastrointestinal transit time and accumulate in the placenta, gonads, frontal cortex and atherosclerotic plaques. Food safety regulations only partially cover chemical pollutants that may be associated with MNPs, while the potential for physical damage caused by MNPs is currently poorly characterised, often varying significantly. We discuss the challenges in the environmental and health risk assessment of MNPs and associated pollutants, which are exacerbated by the lack of both analytical and toxicological data, as well as by the limitations of regulatory and retroactive toxicology approaches.