Soil contaminants at the environment-health interface require function-centered risk assessment

Abstract

Soil-contaminant risk is commonly screened using total concentrations, yet the total fraction alone does not establish biological exposure, ecological impairment, or recovery of soil functions. This Perspective proposes a function-centered extension of established risk assessment, linking sources and legacy stores to soil-controlled speciation, receptor-specific exposure, biological responses, and changes in ecosystem processes. Soil pH, redox conditions, dissolved organic matter, moisture, mineralogy, and particle properties modify the fate of metals and metalloids, organic chemicals, and particulate contaminants. We distinguish potentially accessible contaminant pools from bioaccessibility measured by a specified mobilization assay and from bioavailability to a defined receptor. Geochemical indices and exposure-based hazard quotients retain their screening roles; they are complemented by matched exposure measurements, biological tests, direct process measurements, and uncertainty analysis. An eight-step workflow connects problem formulation, baseline characterization, screening, exposure refinement, functional assessment, risk characterization, intervention selection, and verification. The framework supports contamination monitoring, risk assessment, and remediation evaluation across diverse soil settings. Its proposed decision rule requires acceptable residual exposure, recovery of the specified soil functions, and control of contaminant transfer, with repeated observations to establish durability. The added predictive value of this integration remains a testable proposition rather than an established universal result.