Plastic Wastes in the Aquatic Environment: Ecotoxicological Impacts and Mitigation Strategies

Abstract

Plastic products are in high demand due to their broad applications, resulting to a corresponding rise in the production of plastics. As a result of poor waste management practices such as uncontrolled open dumping, coastal littering, fishing, shipping and other industrial activities, plastics end up in the aquatic environment, where they accumulate as wastes. Recent studies on the abundance/concentration of plastic wastes in the aquatic environment and their resultant ecotoxicological impacts, as well as possible mitigation strategies were reviewed in this paper. Plastics do not decompose easily, and can break down into smaller particles known as nanoplastics (NPs) and microplastics (MPs) which are excellent vectors and sorbents of persistent organic pollutants, heavy metals and pathogenic microbes. NPs and MPs are easily distributed in the environment and also along trophic levels in the food web, and ultimately to humans, while their component chemicals/additives, which are mostly toxic, dissociate and accumulate in living organisms. Multiple studies reported the presence of significant amount of plastics in sediments, water and biota samples. Exposure of aquatic organisms to plastic wastes reportedly caused starvation, entanglement, suffocation, growth retardation, oxidative stress, cytotoxicity, reproductive and metabolic disorders, damage of the digestive tract, mortality, etc. They also induced apoptosis, affected the metabolism of sex hormones, and increased the risk of cancer and metabolic disorder in humans. Proposed mitigation strategies for plastic pollution include recycling and conversion of plastic waste to energy and valueadded products, regulations of usage, reduced usage, bans, use of biodegradable plastics, and public awareness programs.