Microplastics in Soil: An Emerging Threat to Soil Health and Food Safety

Microplastic (MP) pollution is emerging as a serious but often overlooked threat to soil health, agricultural productivity, and environmental sustainability. Although attention to plastic pollution has traditionally focused on aquatic ecosystems, growing evidence shows that agricultural soils are important reservoirs and pathways for MP accumulation. This review synthesizes current knowledge on the sources, occurrence, impacts, detection, and remediation of microplastics in soil. Agricultural plastic mulch, wastewater irrigation, organic amendments and sewage sludge, surface runoff, atmospheric deposition, and degradation of larger plastic materials are identified as major pathways of MP entry into soils. Once present, MPs can alter important soil physical properties, including aggregation, bulk density, porosity, water-holding capacity, and infiltration, while also influencing soil pH, electrical conductivity, nutrient cycling, enzyme activities, microbial biomass, and soil fauna. Their ability to interact with and transport potentially harmful contaminants, including heavy metals and organic additives, may further increase ecological and human-health concerns through plant uptake and food-chain transfer. However, accurate assessment remains challenging because of the diversity of polymer types, particle sizes, shapes, and complex soil matrices. FTIR and Raman spectroscopy are among the commonly used detection techniques, while physicochemical and biological approaches are being explored for remediation. Overall, effective plastic-waste management, preventive measures, improved analytical standardization, and environmentally compatible bioremediation strategies are essential for reducing MP contamination and protecting soil ecosystems and food security.