Microplastics as carriers of heavy metals and pesticides in agricultural soil

Microplastics (MPs) are increasingly pervasive in agricultural soils, primarily originating from plastic mulching, wastewater irrigation, atmospheric deposition and biosolid amendments. Their small size, high surface area, hydrophobicity and variable surface charge enable MPs to adsorb and transport toxic metals and persistent organic pollutants (POPs), thereby enhancing contaminant persistence, mobility and bioavailability in soil-plant systems. This vector effect increases the risk of crop contamination and the transfer of pollutants into the food chain, posing potential threats to the ecosystem and human health. Beyond chemical interactions, MPs alter soil physical properties such as porosity, water retention and aeration, with cascading effects on microbial diversity, enzyme activity and nutrient cycling processes critical for soil fertility. Despite their ecological relevance, MPs remain difficult to detect in complex soil matrices and standardised methods for toxicity assessment are lacking. Future research should focus on improved analytical tools, long-term field investigations and predictive modelling to better understand MP behaviour and cumulative impacts, thereby supporting evidence-based regulations and sustainable agricultural practices to mitigate plastic pollution and protect soil health.