Any dental or medical intervention comes with both risks and benefits, yet some practices persist despite evidence of risks outweighing the benefits. Using mercury amalgam to fill decayed teeth is one of those. Fluoride is another. Its benefits are modest and limited to when it’s applied directly to the teeth. It’s not something to be ingested. Yet well-intentioned folks continue to add it to drinking water.
Lately, much of the research that’s drawn attention has focused on the consequences for children’s developing brains – for good reason, too, as the IQ losses linked to prenatal fluoride exposure have significant lifelong costs seldom taken into account.
One of the newest studies, however, focuses on teens.
Published online last week in Environmental Research, the study involved data from 1841 healthy teens who took part in the National Health and Nutrition Examination Survey (NHANES) between 2013 and 2016, who had measures of fluoride in their blood and drinking water, as well as kidney function.
Why focus on kidney function? Fluoride is excreted mainly through those organs. Yet, according to the study authors, few have considered the possible relationship between
impaired kidney function and high levels of fluoride circulating through the body.
Indeed, when they crunched the numbers, they found that higher levels of fluoride in the body were linked with both higher fluoride levels in drinking water and lower kidney function. The relationship was strongest among those teens with the lowest levels of kidney function.
“Exposure to levels of fluoride found commonly in drinking water in the United States result in significantly higher levels of fluoride in blood in those with lower kidney function,” wrote the authors, led by Dr. John Danziger of Beth Israel Deaconess Medical Center at Harvard Medical School in Boston.
Like any study, this one has its limitations. For one, its authors had to use mathematical estimates of kidney function – a rough measure rather than a precise one; nor did they account for all sources of fluoride the teens may have been exposed to.
While the findings were modest in the young, healthy population studied, the authors expressed their concern that fluoride accumulation may be underestimated in Americans with chronic kidney disease. More research is needed on whether people with kidney disease have a greater susceptibility to fluoride from environmental exposure, Danziger and colleagues concluded.
“Our analysis suggests higher levels of plasma fluoride accumulation in those with lower renal function is of public health concern,” they wrote. “Given that there are more than 20 million Americans living with [chronic kidney disease], among whom the hazard of fluoridation would be highest in those with severe disease, further research is needed to assure water safety for all.”