Microplastics (MPs) in the environment: sources, pathways, human health issues and mitigation strategies

Microplastics (MPs) pollution has become a serious environmental threat in the 21 st century. Plastics are widely used but improperly disposed of, resulting in large amounts of plastic waste that end up in landfills and/or water bodies, contaminating the environment (terrestrial, aquatic, atmospheric, and biotic ecosystems) through various pathways. MPs (particles <5 mm in size), derived from primary and secondary sources, are a heterogeneous mixture of plastic particles of varying shapes, sizes, colors, and chemical composition. Commonly found plastic types include polyethylene terephthalate (PET), polyethylene (PE), polyvinyl chloride (PVC), polypropylene (PP), polystyrene (PS), polycarbonate (PC), polyurethane (PU), and polyester, etc. MPs are ecotoxic and long-lasting (they may persist for 100 to 1000 years) and adversely affect ecosystems, human health, and all other forms of life (aquatic life, wildlife, livestock, birds, etc.). This paper comprehensively reviews existing knowledge on MPs pollution, pathways, fate, and distribution across different ecosystems, their ecotoxic effects, mitigation and remediation strategies, knowledge gaps, and future research recommendations. Several research efforts have focused on developing standardized, efficient analytical techniques for detecting, measuring, and mitigating MPs pollution across different ecosystems, but significant research gaps remain. There is a lack of standard, efficient, and cost-effective analytical techniques suitable for large-scale applications to detect and measure MPs. Sufficient monitoring data on MPs is also scarce and not readily available. The majority of terrestrial sources of MPs remain overlooked and receive inadequate attention in current research efforts. Several knowledge gaps persist regarding current and future environmental and human health risks posed by MPs pollution. Policy measures for the mitigation and remediation of MPs pollution have been discussed.