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DIRECTORY: FAN > Health > Newsletter > Issue # 25

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FAN Science Watch
August 26, 2005

Issue #25: Fluoride & Kidney Damage in Children
By Michael Connett

A new study, published by a team of Chinese scientists, reports that elevated consumption of fluoride during childhood can cause kidney damage. (1) The study follows closely on the heels of another Chinese study finding little to no relationship between fluoride consumption in childhood and tooth decay. (2)

The study on fluoride and kidney damage was conducted by a research team from Tongji Medical College. The team surveyed a group of 210 children, and compared the levels of fluoride in the children’s water, urine, and blood, with indicators of kidney damage (urinary NAG and gamma-GT activity).

According to the authors, “an obvious dose-effect relationship” existed between the children’s water fluoride exposure (over 2 ppm) and the two markers of kidney damage. In other words, the more fluoride the children consumed, the more likely they were to have kidney damage.

Based on the results of the survey, the authors concluded that: “Over 2.0 mg/L fluoride in drinking water can cause renal damage in children, and the damage degree increases with the dinking water fluoride content.”

In contrast to the findings on fluoride/kidney damage, another recent survey of children in China was unable to detect a clear relationship between fluoride ingestion and tooth decay. The survey, led by Dr. Wang Binbin at the Chinese Academy of Sciences, examined tooth decay rates in 830 children and adolescents from 4 Chinese communities with varying levels of fluoride in water (from 1.0 to 3.7 ppm).

When the researchers plotted the incidence of tooth decay by the children’s age, no dose-dependent relationship between water fluoride levels and tooth decay could be discerned – in contrast to what would be expected based on American research. In fact, among the older age groups (15 and 18 year olds), tooth decay was generally highest in the high fluoride areas.

The findings of these two studies call into further question the almost exclusive focus on teeth in western fluoride research, not to mention the safety of the U.S. safe drinking water standard for fluoride. At 4 ppm, the US “safety” standard is almost twice as high as the levels estimated to cause childhood kidney disease in China. So how does this study compare with what we see in the U.S.? We don’t know yet, since no comparable study has yet been conducted.

References:

(1) Liu JL, Xia T, Yu YY, Sun XZ, Zhu Q, He W, Zhang M, Wang A. (2005). [The dose-effect relationship of water fluoride levels and renal damage in children] Wei Sheng Yan Jiu. 34(3):287-8. See: http://tinyurl.com/7gv3h

(2) Binbin W, Baoshan Z, Hongying W, Yakun P, Yuehua T. (2005). Dental caries in fluorine exposure areas in China. Environ Geochem Health. 27(4):285-8. See: http://tinyurl.com/765m2