A Critical Perspective on Nanoplastics in Soil and Crop Systems

Abstract Nanoplastics have emerged as a significant emerging contaminant of the Anthropocene. The ubiquitous presence of nanoplastics attracted considerable attention due to their potential impacts on soil and crop systems. The nanoplastics can be primary and secondary in origin. Their interaction and fate in soil depend on the physicochemical properties, including size, shape, surface charge, hydrophobicity and polymer type. Nanoplastics can both adsorb and leach contaminants, altering soil chemistry and increasing the bioavailability of toxic substances to plants and microorganisms in the rhizosphere. Nanoplastics interferes with soil-plant-microbe interactions, often bringing changes in rhizosphere microbial community composition and function, negatively impacting soil health and crop productivity. Experimental evidence on nanoplastics uptake by roots exacerbates their accumulation in other tissues, including edible plant parts, posing risks to food safety and human health. Nanoplastics are reported to induce oxidative stress in plants and soil microorganisms, impairing key physiological processes and reducing crop yields. Reports of nanoplastic bioaccumulation within the food chain underscore the need for risk assessments. Despite a growing body of evidence, significant knowledge gaps remain, especially in the detection, quantification, and characterisation of nanoplastics in the environment. Even though pyrolysis GCMS can help identify the polymer, the approach provides no information on the shape, number and size of the nanoplastics, which is a severe constraint in assessing nanoplastic contamination and toxicity, which is size dependent. Significant efforts are needed before any realistic ecological impact assessment can be undertaken to understand their long-term environmental and health implications better.