Soil exposure and human health: One Health framework for managing microbial and chemical hazards

Soil contact is a public health paradox: it can expose people to environmental microbiota that may support immune regulation, but it can also transmit pathogens and persistent contaminants. This perspective examines how soils in high-contact settings, including schoolyards, childcare centers, residential gardens, urban farms, and parks, can be evaluated without confusing soil health with human exposure safety. Using One Health len, the paper synthesizes evidence across three linked domains: beneficial microbial exposure, pathogen dynamics, and chemical or particle contaminant transfer. The domains are then organized into a five-step exposure-context framework consisting of evaluating intended use and receptors, reconstructing site history, selecting targeted tests, interpreting exposure pathways, and choosing a management endpoint. The framework adds value to existing soil health and risk assessment approaches by treating microbial benefits as conditional, not automatic, and by requiring health-protective screening before benefits are considered. Four decision endpoints are proposed: unrestricted use, conditional use with controls, remediation before use, or access restriction/alternative land use. For high-risk sites, decisions should be supported by pathway-specific evidence such as bioaccessible metal fractions, PFAS source and depth profiles, pathogen indicators, dust loading, crop uptake, mixture assessment, spatial analysis, and uncertainty evaluation. The framework also identifies mechanisms by which soil microbiota may influence immune regulation, pathogen suppression, contaminant mobility, contaminant bioavailability, and antimicrobial resistance. It also clarifies terminology: soil safety is context-dependent, receptor-specific, so it cannot be inferred from soil fertility alone. This approach helps managers protect children, gardeners, workers, and other exposed groups while preserving safe opportunities for contact with biodiverse soils.