Monitoring fluorine levels in tea leaves from major producing areas in China and the relative health risk

The trace element fluoride can exert a preventive function on dental caries at moderate intake levels, but can also lead to skeletal fluorosis and cognitive impairment when consumed in excessive amounts. Tea is a fluoride hyperaccumulator, yet the risks of fluoride intake via tea consumption are yet to be investigated. In this study, we measured fluoride levels in common tea products from major cultivation provinces in China. Fluoride contents ranged from 6 to 808 mg/kg. Of the samples, 15.6% (34/218) demonstrated fluoride contents which exceeded the maximum residue limit of 200 mg/kg. The samples with high fluoride contents mainly represented oolong tea and dark tea. Fluoride contents in tea were significantly varied between producing regions, which is mainly due to different degree of soil acidification and fluoride occurrence in groundwater. Daily fluoride intake via tea consumption among the general population ranged from 0.02 to 2.20 mg/day, which is lower than the tolerable upper fluoride intake level (UL) of 3.50 mg/day based on Chinese Dietary Reference Intakes, but rather close to the UL of 2.50 mg/day set by the European Food Safety Authority. A risk assessment indicated that the consumption of tea was not associated with any significant health risks (hazard quotient ≤ 0.54). However, we found a potential risk for the simultaneous consumption of tea, drinking water, wheat and seafood based on a simulation assessment. Fluoride intake among the high-risk population should be continuously monitored.