Marine microplastics as vectors of major ocean pollutants and its hazards to the marine ecosystem and humans

TLDR

Microplastic contaminates water, land, air, and groundwater, affecting plants, animals, and humans, and acts as a vector by sorbing pollutants and promoting bioaccumulation in marine ecosystems and food webs. The review aims to assess the risks of pollutant sorption and bioaccumulation by microplastic toward humans, identify dominant sorbed pollutants, and highlight knowledge gaps in microplastic toxicity and influencing factors. The review examines how microplastic sorption and bioaccumulation of pollutants are influenced by factors such as microplastic characteristics, chemical interactions, and environmental conditions in marine ecosystems. The review finds that microplastic is globally abundant with varied types and distribution, that its characteristics and water properties affect pollutant sorption, and that direct medical threats to humans remain unconfirmed despite reported hazards of associated monomers, additives, and pollutants.

Abstract

Abstract Microplastic pollutes water, land, air, and groundwater environments not only visually but also ecologically for plants, animals, and humans. Microplastic has been reported to act as vectors by sorbing pollutants and contributing to the bioaccumulation of pollutants, particularly in marine ecosystems, organisms, and subsequently food webs. The inevitable exposure of microplastic to humans emphasises the need to review the potential effects, exposure pathways, and toxicity of microplastic toward human health. Therefore, this review was aimed to reveal the risks of pollutant sorption and bioaccumulation by microplastic toward humans, as well as the dominant types of pollutants sorbed by microplastic, and the types of pollutants that are bioaccumulated by microplastic in the living organisms of the marine ecosystem. The possible factors influencing the sorption and bioaccumulation of pollutants by microplastic in marine ecosystems were also reviewed. The review also revealed the prevailing types of microplastic, abundance of microplastic, and geographical distribution of microplastic in the aquatic environment globally. The literature review revealed that microplastic characteristics, chemical interactions, and water properties played a role in the sorption of pollutants by microplastic. The evidence of microplastic posing a direct medical threat to humans is still lacking albeit substantial literature has reported the health hazards of microplastic-associated monomers, additives, and pollutants. This review recommends future research on the existing knowledge gaps in microplastic research, which include the toxicity of microplastic, particularly to humans, as well as the factors influencing the sorption and bioaccumulation of pollutants by microplastic.