Fluorine in the environment in an endemic fluorosis area in Southwest, China

Soils in large areas of China are enriched in fluorine (F). The present study analyzed F concentrations in cultivated soil, water, chemical fertilizer, and human hair, and metal concentrations in soils from an endemic fluorosis area in Southwest, China. In order to reveal the effects of industry on F concentration in the environment, 3 towns mainly with agriculture production and another 3 towns with developed phosphorus chemical industry in a same city were selected for sample collection. The total F concentrations of the 277 surface agricultural soil samples were 378.79-1576.13 μg g^-1, and F concentrations of nearly 95% of the soil samples were higher than the Chinese average topsoil F concentration (480 μg g^-1). Only a small fraction (0.75%) of total F was water soluble. The average total F, water soluble F, Ca, Cr, Fe, K, Mn, Rb, and Sr concentrations in soil samples from towns with intensive industry were higher than those from towns mainly with agriculture. Significant correlations were found between soil pH with total F (p < 0.01) and with water soluble F concentration (p < 0.1). Low F concentrations (<0.5 mg L^-1) were found in irrigation water, well water and tap water in a town where the industry is dense. The phosphorus fertilizer and compound fertilizer had hundreds of times of contribution to soil F increment than the nitrogen fertilizer and potassium fertilizer. Nearly half percent of F in the human hair samples was of exogenic origin. Based on soil ingestion pathway, the health risk for adults exposure to F in soils was acceptable, however, F may pose possible health risks to children in high F concentration areas.