Distribution, co-existing metals, and potential health risk of fluorine in farmland soil in different anthropogenic activity dominated districts in a county-level city in Sichuan province, Southwest China, in 2015.

Continuous fluorine (F) accumulation in soil by anthropogenic activities leads to variously global environmental and health issues. Herein, 300 farmland soil samples were collected from different anthropogenic activity dominated districts for studying the distribution and related health risk of F in soils. Co-existing metal concentrations in soil samples were also analysed to evaluate the relationship between the distribution of F and metals in soil. The median value of the total F concentration of 488 mg kg in the present samples was higher than the median background F concentration in topsoil in Sichuan province of China (261 mg kg). Concentration of water-soluble F (1.33-26.2 mg kg) was two or three orders of magnitude less than that of total F in soil. Levels of total and water-soluble F in soils collected from the district with longer contamination history were higher than that from other districts with shorter contamination period, indicating a historical contribution of anthropogenic activities to F accumulation in soil. Notable positive correlation between the total F and vanadium (V) concentration in soil can be partly linked to the usually negative charged form or a common source of F and V in soil (e.g. coal combustion). Compared with inhalation and dermal contact, present human exposure of F in soil was mainly caused by oral ingestion, and the health risks posed by F in soil for both children and adults were acceptable. However, considering the higher potential risk for children than adults, the accumulation of F in soil induced by anthropogenic activities should not be neglect.