Human health concerns regarding microplastics in the aquatic environment - From marine to food systems

Marine plastic waste pollution is one of the most urgent global marine environmental problems worldwide. It has attracted worldwide attention from governments, the public, the scientific community, media and non-governmental organizations and has become a hot issue in current marine ecology and environmental research. This research aimed to conduct a traditional review of the current state of the art regarding microplastics (MPs) definition and characterisation, including an assessment of MPs detected in marine and food systems. The review revealed that plastic waste is not biodegraded and can only be broken down, predominantly by physical processes, into small particles of micron to nanometre size. Particles (<150 μm) can be ingested by living organisms, migrate through the intestinal wall and reach lymph nodes and other body organs. The primary pathway of human exposure to MPs has been identified as gastrointestinal ingestion (mainly seafood for the general population), pulmonary inhalation, and dermal infiltration. MPs may pollute drinking water, accumulate in the food chain, and release toxic chemicals that may cause disease, including certain cancers. Micro/nano-plastics may pose acute toxicity, (sub) chronic toxicity, carcinogenicity, genotoxicity, and developmental toxicity. In addition, nanoplastics (NPs) may pose chronic toxicity (cardiovascular toxicity, hepatotoxicity, and neurotoxicity). The toxicity of MPs/NPs primarily depends on the particle size distribution and monomeric composition/characteristics of polymers. Polyurethane (PUR), Polyacrylonitrile (PAN), Polyvinyl chloride (PVC), Epoxy resin, and Acrylonitrile-butadiene-styrene (ABS) are categorised as the most toxic polymers based on monomer toxicity. MP detection methods include combinations of spectroscopic analysis (RS and FTIR) and chromatography (TED-GC/MS). MP/NP toxicological properties and general quantitative and qualitative analysis methods used in MPs Risk Assessment (RA) are summarised. A robust dose-response model for MPs/NPs requires further investigation. This study lays the foundation for the evaluation of MP/NP risk assessment in the marine ecosystem and potential implications for human health.