Current State of Research on the Prevalence of Microplastics in Aquatic Fish and Their Impact on Health

Tiny plastic particles, known as microplastics, are formed through the degradation of larger plastics and have become ubiquitous in the environment as solid waste, affecting aquatic life. Aquatic organisms, especially fish, ingest these microplastics, which have a negative impact on fish health. This comprehensive review article identified seven continents and their aquatic fish populations affected by microplastic contamination, examining the effects on fish physiology and toxicosis, as well as the nature, size, and types of microplastics. Increasing evidence suggests that microplastics trigger undesirable and hazardous interactions with fish tissue, generating hazardous intermediate metabolites and molecules, including reactive oxygen species. Biotransformation followed by bioaccumulation (and vice versa) may be an essential phenomenon for the toxic response of these emerging microplastic particles. This review summarises the current knowledge on the physicochemical nature of microplastics worldwide and their varying levels of toxicity in aquatic fish, including numerous biochemical pathway alterations in a natural environment in the presence of microplastics. This review identified that benthopelagic fish were used maximally in experiments worldwide to determine the presence of microplastics in their bodies, and marine fish were investigated 2.6 times more than freshwater fish. This article also outlines a future direction, highlighting gaps in advanced microplastic toxicity research, including the omics approach and computational studies, and suggests a few recommendations for monitoring and modifying global microplastic and plastic waste management policies.