Microplastics and heavy metals dynamics: a potential threat to soil health and food safety

Microplastics (MPs) and adsorbed heavy metals (HMs) pose a potential threat to agricultural soil, crops, and is a challenge for food safety. MPs < 1 μm in size are absorbed by crops from the agricultural soil and cause physiological disturbances in plant bodies, ultimately affecting plant metabolic activities. Furthermore, MPs adsorb HMs on their surfaces, affecting their availability for plants. Previous research studies have focused on the adsorption/desorption of HMs but lack a clear mechanism, duration of adsorption, and influencing factors under field conditions. Most research studies have focused on laboratory-controlled experiments, while very limited research exists under field conditions where MPs-soil-plant interactions and complex soil chemistry are discussed. Therefore, research in field conditions (where other influencing factors also exist) is needed for a better understanding of the MPs adsorption/desorption mechanism, duration of desorption, influencing factors, and their effects on plant physiology for different HMs. This review discusses adsorption/desorption of HMs, impact on soil health, and crop physiology. Significant research gaps exist in MPs transport, adsorption/desorption mechanisms, influencing factors, and impacts on crop physiology, which need to be studied in field conditions. Filling the gaps in existing knowledge and enhancing interdisciplinary research will be crucial in creating effective strategies to reduce the effects of MPs pollution in agricultural systems, which will ensure environmental sustainability and food safety.