A study has raised questions about the safety of fluoride exposure, especially for adolescents (Environment International, Aug. 8, 2019). This is one of those chicken-or-egg-kind of studies. Fluoride may affect both kidney and liver function but altered kidney and/or liver function may impact absorption of fluoride. Which comes first?
Fluoride Exposure and Kidney and Liver Function:
Scientists used data from the National Health and Nutrition Examination Survey [NHANES] on nearly 2,000 adolescents who had blood levels of fluoride measured. In addition, 1,742 teens in the study had measurements of fluoride in their household tap water.
None of the young people had kidney disease, but measurements of their kidney and liver function were worrisome. Those with the highest blood levels of fluoride had lower kidney function. A similar association was found for those whose household water was high in fluoride.
In Their Own Words:
The authors of this study share the chicken-or-egg analysis:
“Higher plasma fluoride concentrations were associated with changes in kidney and liver related parameters.
“Given the cross-sectional nature of this study, there are several possible interpretations for the findings. First, fluoride exposure may contribute to complex changes in kidney and liver parameters among U.S. adolescents. This possibility is supported by the consistency of our findings with research demonstrating a dose-response relationship between water fluoride levels above 2 mg/L and enzyme markers of liver and kidney dysfunction… Chronic low-level fluoride exposure is also associated with decreased thyroid gland activity among children and adults… Thus, fluoride exposure could potentially compromise kidney function via glomerular damage, or indirectly via suppression of the thyroid gland.”
“An alternative interpretation for our findings is that poorer kidney function may contribute to increased plasma fluoride levels rather than resulting from them.”
Making Sense of Medical Mystification:
In other words, does fluoride exposure cause changes in liver and kidney function or does “poorer kidney function” lead to higher levels of fluoride circulating in the body? The authors offer a third possibility. Fluoride exposure could impair kidney function which leads to diminished excretion of fluoride which in turn increases absorption of fluoride which then leads to poorer kidney function. Chicken-egg-chicken or, if you prefer, egg-chicken-egg!
What Should We Conclude from This Research?
Here’s what we do know:
- Research on animals demonstrates that fluoride, even at relatively low levels, can be toxic to liver and kidneys.
- Kidneys and livers accumulate fluoride in humans.
- Fluoride research in humans is limited. Nevertheless, there are data hinting that fluoride exposure is associated with kidney and liver toxicity.
- Fluoride exposure affects thyroid function, which could indirectly impact kidney function.
What We Don’t Know:
- Does fluoride cause altered kidney function or does altered kidney function increase fluoride absorption?
- Does fluoride exposure affect kidney function in younger children?
- Are otherwise healthy adults impacted by exposure to higher levels of fluoride?
- Are people with reduced kidney or liver function more susceptible to toxicity from fluoride?
We find it shocking that after 70+ years we do not have answers to these important questions.
The authors of this study suggest that:
“further studies are needed to examine the mechanisms by which chronic low-level fluoride exposure may impact kidney and liver related parameters during development and adolescent life stages…”
We couldn’t agree more, but we wish those studies had been done before tens of millions of people were exposed to chronic low-levels of fluoride.
Read more about new research regarding fluoride exposure and IQ at this link.
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