Intake of fluoride and other Hofmeister ions from black tea consumption in CKDu prevalent areas, Sri Lanka

Dietary exposure of selected Hofmeister ions—fluoride, chloride, sulfate, phosphate, sodium, potassium, magnesium, and calcium from black tea consumption in chronic kidney disease of unknown etiology (CKDu) prevalent areas in Sri Lanka—were assessed in order to understand exposure and risk. Black tea samples (n = 25) were collected from CKDu prevalent areas and control areas (n = 15). Total fluoride content in alkali fused digested black tea samples was determined. The available Hofmeister ions in tea infusions prepared using deionized water and the groundwater collected by CKDu endemic areas were compared. Dietary exposure was calculated by chronic daily intake data. Total fluoride concentrations ranged from 80 to 269 mg/kg in tea collected from the CKDu endemic regions and 62.5–123.5 mg/kg in non-endemic regions. The fluoride content in infusions ranged from 1.45 to 2.04 mg/L in CKDu endemic areas and 1.11–1.38 mg/L in control samples. The infusions prepared with local groundwater from the CKDu endemic areas showed an elevated level of fluoride 95% than that of the infusion prepared using same tea with deionized water. Aggregated chronic daily intake value from tea and groundwater exceeds the estimated adequate daily intake value of fluoride. The hazard quotient (HQ) values of fluoride in 5 min and 120 min tea infusions were 1.60 and 2.20, respectively, and indicate an adverse health risk. Potassium content in tea infusions collected from CKDu endemic areas is higher than in the control. Even though these values are less than the adequate intake, it may pose an impairment on a weak kidney. Chronic daily intake of Hofmeister ions, i.e., fluoride and potassium from black tea consumed in CKDu endemic areas may induce a risk for CKDu. Graphical abstract: [Figure not available: see fulltext.]