Fluoride in Agriculture: From Sources and Soil Mobility to Crop Toxicity, Food-Chain Exposure, and Risk Mitigation—A Critical Review (2016–2026)

Abstract

Fluoride is ubiquitous in agricultural environments, yet researchers often misclassify agricultural risk by treating total concentrations in soil, water, fertilizers, and plant tissues as interchangeable exposure indicators. This critical review synthesizes evidence published from 2016 to September 2026 across the water–soil–plant–food continuum and addresses a decision-oriented question: under which combinations of source intensity, geochemistry, crop biology, and management does fluoride become agronomically damaging or relevant to food and feed safety? The review integrates geogenic inputs, phosphate fertilizers, industrial deposition, and irrigation with evidence on soil sorption, mineral precipitation, speciation, root and foliar uptake, physiological injury, transfer to edible tissues, dietary exposure, co-contaminant interactions, and remediation. Across the literature, pH, calcium availability, aluminum and iron phases, clay mineralogy, bicarbonate and sodium chemistry, and exposure duration repeatedly decouple total fluorine inventory from mobile or plant-available fluoride. Plant response is likewise non-universal: species and cultivars differ in uptake, transport, fluoride-export capacity, antioxidant defense, and yield sensitivity. Tea and selected food crops can represent important exposure pathways, whereas field evidence for many proposed amendments remains less mature than laboratory evidence. A hierarchical management strategy is therefore proposed: prevent new loading, diagnose the dominant mobility mechanism, reduce fluoride mobility with mechanism-compatible interventions, select crops or cultivars when necessary, measure fluoride in edible tissues rather than relying on soil totals, and verify performance through multi-season field studies. Priority research needs are standardized bioavailability metrics, matched monitoring of water–soil–crop compartments, realistic co-contaminant assessment, and field validation that includes agronomic performance, durability, and cost.