The fluoride problem: Scientific community can't agree on its effects on IQ
TUESDAY, MAY 27, 2014 11:20 AM

Fluoride is a chemical commonly used to purify water meant for drinking, meaning that most people ingest it without thinking about it - it's also found in dentistry products. However, some speculate that such fluoride exposure is bad for human health and, more specifically, can reduce a child's IQ score. According to a study conducted by the Harvard School for Public Health, a high amount of fluoride exposure during childhood can significantly decrease IQ. While the Harvard study suggested a link between the chemical and IQ, some studies say otherwise. 

A lower intelligence 
Researchers with the Harvard study analyzed the data of children exposed to fluoride in China. All the kids studied were ages 14 and younger. Those who experienced fluoride exposure had a lower IQ score than those who were not exposed to fluoride.

"Fluoride seems to fit in with lead, mercury, and other poisons that cause chemical brain drain," Philippe Grandjean, adjunct professor of environmental health at Harvard, said in a statement. "The effect of each toxicant may seem small, but the combined damage on a population scale can be serious, especially because the brain power of the next generation is crucial to all of us."

The study suggested that even small doses of the chemical can be toxic to children. However, the Harvard results differ from those of other research.

No found connection
According to a study conducted by researchers from the University of Otago, Dunedin, New Zealand, fluoride exposure does not affect IQ. These findings contradict the Harvard study and call into question the popular notion that the chemical can negatively impact intelligence. Researchers analyzed the data of children living in the town of Dunedin between the years 1972 and 1973. During that time, drinking water was purified with fluoride. Researchers specifically looked at children who ingested the water when they were about 5 years old. They then checked the IQ score of those same children when they were between the ages of 7 and 13, then again at age 38.

Researchers concluded there was no connection between IQ and fluoride exposure. The control group (those not exposed to fluoride) did not have a significantly different IQ than the children who were exposed. The control group also accounted for possible altering factors such as socio-economic status of parents, breastfeeding and birth weight. 

Conclusions
Both studies assessed data from different parts of the world. Perhaps the fluoride levels in China (where Harvard researchers found an association with lower IQ) were higher than those in New Zealand. Or, the Harvard study may not have accounted for additional factors, such as the effect of other chemicals on IQ. Either way, the scientific community seems to be at odds.