Children exposed to higher fluoride levels have lower IQs, a government study finds

CNN — A rigorous nine-year research review looking at the relationship between fluoride and intelligence in children concludes that as fluoride levels rise, IQ drops. In a second analysis of studies with group-level measurements of fluoride in urine and water, the researchers found a slightly more than 2-point drop in IQ between the highest and lowest fluoride levels. When they restricted their analysis to the four studies with the lowest risk of bias in their data, they found that children drinking water with 2 parts per million of fluoride had IQ scores that were almost 5 points lower, on average, compared with those who weren’t exposed to lower levels. In a group of four studies with a low risk of bias that reported group-level measures of fluoride in urine, they found that people with less than 1.5 parts per million in their urine – a measure of all the sources they consume, not just water – had IQ scores that were about 1 point lower on average than those exposed to lower levels. The researchers found that every 1 part per million increase in fluoride in urine was associated with about a 5 point drop in IQ in boys but not girls.