Toxicological Impacts and Microbial-Mediated Degradation Processes of Microplastics

Abstract

Synthetic plastics are essential elements of our daily life; therefore, their accumulation in the environment is a subject of major concern, owing to their nondegradability and detrimental effects on the environment. When plastics are disposed of as solid waste, they enter landfills and eventually fragment into tiny particles (<5 mm), known as microplastics (MPs), which come into aquatic environments and are taken up by the different aquatic flora and fauna present in different layers. The consumption of these edible aquatic organisms by higher trophic levels, including human beings, poses a significant threat to food safety and human health. This toxicity plays a crucial role in bioaccumulation within food chains and contributes to ecological toxicity. Drilling fluids, pharmaceutical vectors, industrial processes, and mechanical and chemical degradation of large plastic debris are the primary and secondary sources of MPs in the environment. Several physical treatments and chemical treatment processes have been employed for the degradation of MPs. Conventional degradation methods contribute to pollution, prompting exploration of biological degradation. Biodegradation involves biofragmentation, biodeterioration, assimilation, and mineralization, aligning with sustainable principles. The biodegradation efficiency of algae is less understood, compared with that of bacteria and fungi. This article explores microbial degradation of MPs using micro-organisms and microbial products (e.g., enzymes), emphasizing sustainable practices and addressing the urgency of mitigating environmental damage. This study supports a sustainable future by concentrating on biodegradation’s compatibility with the UN Sustainable Development Goals (SDGs), while also stressing MPs’ toxicological impact.