August 08, 2019
2 min read

Fluoride exposure may reduce kidney, liver function in adolescents

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Ashley J. Malin

Chronic low-level fluoride exposure contributed to small reductions in kidney and liver function among adolescents, according to a recently published study. In addition, researchers found adolescents who already had poorer kidney and/or liver function may absorb more fluoride in their bodies.

“Approximately 74% of the United States population that relies on public water distribution systems receives chemically fluoridated water for the purpose of preventing tooth decay,” Ashley J. Malin, PhD, postdoctoral fellow in the department of environmental medicine and public health at the Icahn School of Medicine at Mount Sinai, and colleagues wrote. “Among healthy adults, approximately 60% of absorbed fluoride is excreted in the urine by the kidneys, while the corresponding percentage among children is approximately 45%. The kidneys, followed by the liver, accumulate more fluoride than any other organ system in the body.”

Malin told Healio/Nephrology that, “While many animal studies have demonstrated toxic effects of fluoride on the kidneys and liver, even at low levels, this is the first human study to examine the association of fluoride exposure with kidney or liver function in the United States.”

Using data from the National Health and Nutrition Examination Survey, researchers conducted a cross-sectional study of 1,742 adolescents aged between 12 and 19 years who did not have kidney disease (mean age, 15.4 years). Fluoride concentrations were measured in blood plasma (median, 0.33 µmol/L) and household tap water (median, 0.48 mg/L). To assess kidney function, researchers considered eGFR, serum uric acid and urinary albumin creatinine ratio. For liver function, alanine aminotransferase, aspartate aminotransferase, alkaline phosphate, blood urea nitrogen, gamma glutamate transferase and albumin were assessed.

Tap water 
Chronic low-level fluoride exposure contributed to small reductions in kidney and liver function among adolescents.
Source: Adobe Stock

Researchers found a 1 µmol/L increase in plasma fluoride was associated with a 10.36 mL/min/1.73m2 lower eGFR, a 0.29 mg/dL higher serum uric acid concentration and a 1.29 mg/dL lower blood urea nitrogen concentration. In addition, researchers observed that a 1 mg/L increase in water fluoride was associated with a 0.93 mg/dL lower blood urea nitrogen concentration.

“Small reductions in kidney function early in life may increase the risk of kidney disease later in life,” Malin said. “Additionally, greater bodily fluoride absorption may increase the risk of other adverse health effects of fluoride exposure. Prospective studies examining the impact of chronic low-level fluoride exposure on kidney and liver function at different time points throughout the life course are warranted.” – by Melissa J. Webb

Disclosures: The authors report no relevant financial disclosures.