Microplastics in animal nutrition: Occurrence, spread, and hazard in animals

Abstract

Microplastics (MPs) are small plastic particles less than 5 mm in size, which have become a common environmental contaminant, spreading across terrestrial and aquatic ecosystems. Concerns have been raised about the impact of microplastics on animal health and nutrition due to their accumulation and potential transfer through the food chain. This review aims to summarize current knowledge about microplastics in animal nutrition, with a focus on their occurrence, sources, routes of exposure, and potential effects on animal physiology and metabolism. Animals can consume microplastics through a variety of routes, including direct consumption of contaminated food, uptake from contaminated water, and ingestion of organisms that have already consumed microplastics. MPs have been found in a variety of animal species, including fish, birds, mammals, and invertebrates, highlighting the possibility of widespread exposure and bioaccumulation. MPs can interact with the gastrointestinal tract after being ingested, potentially influencing nutrient absorption, gut microbiota composition, and overall digestive efficiency. MPs may also act as carriers for other chemical pollutants, potentially increasing their bioavailability and toxic effects on animals. While some studies indicate that microplastics may cause adverse effects in animals such as inflammation, oxidative stress, and disruption of endocrine functions, the overall health effects and long-term consequences of microplastic (MP) exposure in animal nutrition remain unknown. Furthermore, the review discusses the potential consequences of microplastics in animal-derived food products, considering the human health risks associated with their consumption.