Researchers recently looked at the IQs of 512 Chinese grade-schoolers from two otherwise similar villages, except for the amount of fluoride they were drinking in their water. In the village with high fluoride in their water, the children were less intelligent – and far more apt to be mentally retarded – than the children from the village with low fluoride in the water. Actually, the children drinking less fluoride had about half the fluoride in their blood – and on average, an IQ about 8 points higher.

The Chinese children were drinking well water with naturally occurring fluoride. However, in the U.S., governments often mandate water fluoridation. Seventy percent of the water in the U.S. is fluoridated and even by drinking purified water, most people absorb a gallon of fluoridated water in each shower.

In the low fluoride village, about 28 percent of the children had IQs indicating bright normal or high intelligence. However, in the high fluoride village less than a third of that number – only about 8 percent – had bright normal or high intelligence. In the village with more fluoride, over 15 percent of the children had IQs indicating mental retardation or borderline retardation; whereas, only about 6 percent in the low fluoride village had this problem. The results were clear: the children drinking more fluoride were about two and a half times more likely to have mental retardation.

In either of the villages, the children with scores showing mental retardation or borderline retardation had more fluoride in their blood than any of the other children. The researchers state, “As the fluoride level in children’s serum increased, the children’s IQs fell and the rates of borderline or lower intelligence increased.” Of course, it’s impossible to say what the children’s IQs would have been, even in the low fluoride village, if they – and their parents – haven’t been exposed to fluoride in their water at all. One can bet they would have been much higher.

In the high fluoride village, the average fluoride in the water was 2.47 mg/L (milligrams per liter). In the low fluoride village, the average was .36 mg/L. In the U.S., the CDC recommends water fluoridation between 0.5 to 1.2 mg/L and considers water with 0.7 mg/L or higher to have “substantial” fluoride. The EPA’s maximum for fluoride in our water is 4 mg/L – which is well over the amount causing retardation in these children. In the U.S., about one in ten children has a learning disability.

According to the CDC, over forty percent children from 12 to 15 also have dental fluorosis. Dental fluorosis is caused by high exposure to fluoride (some would say fluoride poisoning) and is characterized by visible white stains on the teeth. About two dozen human studies link fluoride with low IQ and over a hundred animal studies link fluoride to brain damage. Still more research connects fluoride with thyroid disease and cancer. Many countries around the world add fluoride to the salt, if it’s not easy to reach the population through the water supply.