Exposure to fluoride may lower children's intelligence, says a study published in Environmental Health Perspectives, a publication of the National Institute of Environmental Health Sciences. Fluoride is added to 70 percent of U.S. public drinking water supplies.

For the study, 512 children aged 8-13 years in two Chinese villages were tested – Wamaio with an average of 2.47 mg/L water fluoride (range 0.57-4.50 mg/L) and Xinhuai averaging 0.36 mg/L (range 0.18-0.76 mg/L). About 28 percent of the children in the low-fluoride area scored as bright, normal or higher intelligence compared to only 8 percent in the high fluoride area of Wamaio.

In the high-fluoride city, 15 percent had scores indicating mental retardation and only 6 percent in the low-fluoride city. The authors of the study eliminated both lead exposure and iodine deficiency as possible causes for the lowered IQs. They also excluded any children who had a history of brain disease or head injury and none drank brick tea, known to contain high fluoride levels. Neither village is exposed to fluoride pollution from burning coal or other industrial sources, said the study.

Paul Connett, director of the Fluoride Action Network, says: This is the 24th study that has found this association, but this study is stronger than the rest because the authors have controlled for key confounding variables and in addition to correlating lowered IQ with levels of fluoride in the water, the authors found a correlation between lowered IQ and fluoride levels in children's blood. This brings us closer to a cause and effect relationship between fluoride exposure and brain damage in children.

What is also striking is that the levels of the fluoride in the community where the lowered IQs were recorded were lower than the EPA's so-called 'safe' drinking water standard for fluoride of 4 ppm and far too close for comfort to the levels used in artificial fluoridation programs (0.7 – 1.2 ppm), says Connett. The study authors write: In this study we found a significant dose-response relation between fluoride level in serum and children's IQ.

Tara Blank, the Science and Health Officer for the Fluoride Action Network, says: This should be the study that finally ends water fluoridation. Millions of American children are being exposed unnecessarily to this neurotoxin on a daily basis. Who in their right minds would risk lowering their child's intelligence in order to reduce a small amount of tooth decay, for which the evidence is very weak?