This analysis refers to the study by Choi et al., Developmental Fluoride Neurotoxicity: A Systematic Review and Meta-Analysis, published in Environmental Health Perspectives, online July 20, 2012. See abstract.

Pew Children’s Dental Campaign (July 31, 2012)
Analysis of the Environmental Health Perspectives Article
About Fluoride & Neurotoxicity

1.       The article in Environmental Health Perspectives does not
raise valid concerns about water fluoridation in the U.S.  The article
reviewed studies on IQ scores for children living in areas of China,
Mongolia and Iran where the water supplies have unusually high,
natural fluoride levels.  In many cases, the high-fluoride areas were
significantly higher than the levels used to fluoridate public water
systems in the U.S.  In fact, the high-fluoride areas in these foreign
countries reached levels as high as 11.5 mg/L, which is more than 10
times higher than the optimal level used in the U.S.

2.       This article offers a meta-analysis, and its credibility
hinges on whether good-quality studies are reviewed.  Yet the
article’s co-authors admit that “each of the [studies] reviewed had
deficiencies, in some cases rather serious, which limit the
conclusions that can be drawn.”  Although the studies compared
high-fluoride with low-fluoride areas, the authors acknowledge that
“the actual exposures of the individual children are not known.”

3.       The studies found very little difference in IQ scores between
children in the high-fluoride and low-fluoride groups.  In addition,
the authors acknowledge that the average standardized mean difference
(0.45) in IQ scores “may be within the measurement error of IQ
testing.”

4.       A 2009 animal study found that even at fluoride levels that
were up to 230 times higher than the typical human consumes, there was
“no evidence of learning deficits in any of the fluoride-exposed
groups.”

5.       The co-authors reached a weak conclusion, writing that “our
results support the possibility of adverse effects … on children’s
neurodevelopment.”  And the authors called for more and better-quality
research, including more “precise” data on the children involved and
greater confidence that other factors have been ruled out as reasons
for the IQ differences.  Given the very small difference in IQ scores,
it’s possible that arsenic levels, school quality, nutrition, parents’
educational levels and other factors could have shaped the results.
The authors also added that “reports of lead concentrations in the
study villages in China were not available”— another factor that could
not be ruled out.  A British research team reviewed similar Chinese
data and reported that “water supplies may be contaminated with other
chemicals such as arsenic, which may affect IQ.”