Microplastic Contamination across the Soil-Plant-Human Continuum: Mechanisms and Chain-Specific Governance

The widespread contamination of agricultural soils with microplastics (MPs), primarily resulting from plastic mulching and organic amendments, has transformed these systems into long-term sinks for plastic particles. This perspective synthesizes current knowledge on the transport and impacts of MPs across the soil-plant-human continuum. We underscore the pathways by which MPs infiltrate crops via root uptake and foliar deposition, accumulate in edible tissues, and ultimately reach humans through dietary exposure. The associated health risks, including gastrointestinal accumulation, systemic inflammation, endocrine disruption, and the co-transport of adsorbed toxic pollutants, raise pressing concerns for food safety and public health. Moving beyond presence-based assessments, we integrate field-relevant effect thresholds with polymer-specific sorption behaviors to predict cascading impacts along the exposure pathway. Furthermore, we propose a transdisciplinary Soil–Plant–Food (SPF) governance framework that emphasizes actionable strategies for source reduction, process interception, and endpoint regulation. We further call for harmonized monitoring protocols, the establishment of maximum residue limits, and the development of targeted mitigation technologies to enable evidence-based risk management and protect food security and human health.