The adverse health effects of increasing microplastic pollution on aquatic mammals

Microplastics (MPs), an emerging ubiquitous pollutant in the aquatic ecosystem, pose serious health concerns to the survival of aquatic fauna, especially top predators (e.g., aquatic mammals). It is challenging to investigate the toxicological profile of MPs in aquatic mammals due to their diverse toxicological behaviour, physico-chemical properties, and other technical and ethical issues. This study reviewed the current burden of MPs in the aquatic ecosystem, the occurrence of MPs in the various tissues of aquatic mammals, its composition (heavy metals, pesticides, pathogens), and possible health effects on individual and population levels in aquatic mammals. Aquatic mammals are constantly exposed to MPs directly and indirectly via the food-web. The MPs and a wide range of toxic heavy metals, pesticides, and pathogens added during manufacturing or adsorbed from the surrounding environments are bioaccumulated in aquatic mammals for years. Due to their long life-span and heavy body masses, these pollutants can cause several serious health issues in aquatic mammals that can drastically reduce the population size and ultimately can cause extinction, especially in vulnerable populations. Still today the toxicological profile of MPs and its presence in other deep tissues largely remains unknown in aquatic mammals. We therefore suggest a global assessment of the risks associated with the consumption of MPs by aquatic mammals and the presence of MPs in their habitats. (c) 2022 The Author(s). Published by Elsevier B.V. on behalf of King Saud University. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).