Fluoride Exposure and Kidney and Liver Function among Adolescents in the United States

Abstract

PDS 63: Chemicals and metals: health effects, Exhibition Hall (PDS), Ground floor, August 27, 2019, 10:30 AM - 12:00 PM Background/Aim: Hepato- and nephrotoxicitiy of fluoride have been demonstrated in animals, but few studies have examined potential effects in humans. We hypothesized that adolescents with greater fluoride exposure would have poorer kidney and liver function. Methods: We conducted a population-based cross-sectional study to examine the relationship between fluoride exposure and kidney and liver function among adolescents in the United States (U.S.), utilizing data from the National Health and Nutrition Examination Survey (2013-2016). Fluoride was measured in plasma and household tap water; kidney and liver parameters were measured in serum samples. We analyzed data from 1,983 and 1,742 healthy adolescents who had plasma and water fluoride measures respectively, as well as kidney and liver measures. These population-based samples represent 25,930,302 and 23,287,332 adolescents respectively. We employed survey-weighted linear regression to examine relationships between fluoride exposure and kidney and liver parameters after adjusting for covariates. Covariates included age, sex, race, socioeconomic status, body mass index and daily protein intake. A Holm-Bonferroni correction accounted for multiple comparisons. Results: A 1 µmol/L increase in plasma fluoride was associated with a 10.36 mL/min/1.73 m2 lower estimated glomerular filtration rate [95% CI: -15.93, - 4.79; p =0.002], a 0.29 mg/dL higher serum uric acid level [95% CI: 0.08, 0.50; p =0.04], and a 1.29 mg/dL lower blood urea nitrogen level [95%CI: -1.87, -0.70; p < 0.001]. A 1 mg/L increase in water fluoride was associated with a 0.93 mg/dL lower blood urea nitrogen level [95% CI: -1.39, -0.47; p =0.001] and a 0.06 g/dL lower serum albumin level [95% CI: -0.10, -0.02; p =0.05]. Conclusions: Fluoride exposure may contribute to complex changes in kidney and liver related parameters among U.S. adolescents. As the study is cross-sectional, reverse causality cannot be ruled out; therefore, altered kidney and/or liver function may impact bodily fluoride absorption and metabolic processes.