Microplastics flow in the food chain through agricultural practices: quo vadis

Abstract

The plastic particles with a diameter of less than 5 mm are called microplastics (MPs) and have become persistent contaminants of the environment with important implications for agricultural systems and food safety. This review aims to integrate the current understanding of sources, transport, and effects of MPs in agricultural landscapes, with a particular focus on their subsequent transport within the food web chain. MPs in agricultural soils may enter through various routes, such as the application of sewage sludge, degradation of plastic mulch films, irrigation with contaminated water, and atmospheric deposition. Once introduced, they enter the food chain under the influence of soil properties, microbial communities, and plant systems, impacting soil fertility and nutrient cycling. Transport of MPs from soil to root, followed by uptake and translocation to edible organs, is a food safety and human health issue. MPs also serve as vectors of agrochemicals, heavy metals, and pathogens, increasing their ecotoxicological and toxicological risks. MPs also affect soil structure, decrease microbial diversity, and impact yields. Therefore, this review highlights essential knowledge gaps regarding the long-term persistence of MPs in soils, bioavailability, and impact, which could be cumulative along the trophic chain. For this, regulation systems, agricultural practices, and detection and mitigation strategies, qualitative and quantitative, for MPs should be devised.