Microplastics across marine food webs: bioaccumulation, exposome interactions, and emerging oncogenic risks

Microplastic pollution is a major environmental problem affecting ecosystems, wildlife and people worldwide. Microplastics are solid synthetic polymer particles > 5 mm, insoluble in water and potentially containing functional additives and adsorbed chemical contaminants. They originate from bulk industrial products and from the degradation of large plastic debris (EFSA CONTAM Panel, in EFSA Journal 14, 2016). The extent of the contamination is critical, with global plastic production projected to exceed 1.2 billion metric tons per year by 2060 and an estimated 170 trillion plastic particles in the world's oceans at present. The globular morphology of microplastics provides them with the property of high physicochemical stability and a very high surface area to volume ratio. Thus, facilitating the adsorption of toxic chemicals, heavy metals, and persistent organic pollutants onto their surfaces and acting as mobile vectors of environmental toxicity. It reviews the microplastic bioaccumulation, ecological effects, and toxicological effects, including possible oncogenesis. There is evidence for the ingestion of microplastics by marine organisms, from plankton to highly trophic predators, which allows for trophic transfer and biomagnification through food chains, ultimately putting humans at risk through seafood consumption, with reported concentrations of 0.2-7 particles per gram wet weight in commercially important marine species. Microplastics have recently been identified as a key component of the human exposome and a potential risk factor for chronic diseases because of interaction effects with, among others, exosomal signals and genome stability. This review covers mitigation strategies including policy interventions such as the UN Global Plastics Treaty, biodegradable materials and bioremediation methods, biosurfactant-modified nanofiber filtration systems with removal efficiencies up to 99%, and artificial intelligence (AI)-derived environmental sensing technologies. However, there are significant knowledge gaps in rapid advances in dose-response relationship determination, generalizable nanoplastic detection methods, and long-term epidemiology that shows a cause-and-effect relationship between environmental exposure and clinical outcomes. This indicates a requirement for interdisciplinary expertise in dealing with microplastic hazards in marine ecology, toxicology, biomedical science, and environmental governance.