Saw this intriguing tidbit on Kelly the Kitchen Kop‘s blog, and had to head on over to the National Institutes of Health to check it out.

Yup, it’s true. A distinguished team of researchers at the Harvard School of Public Health explored the relationship between exposure to high levels of fluoride and childhood neurological development, and found that high exposure to fluoride depressed IQ. To quote from the abstract:

Developmental Fluoride Neurotoxicity:
A Systematic Review and Meta-Analysis

Anna L. Choi, Guifan Sun, Ying Zhang, and Philippe Grandjean

Background: Although fluoride may cause neurotoxicity in animal models and acute fluoride poisoning causes neurotoxicity in adults, very little is known of its effects on children’s neurodevelopment.

Objective: We performed a systematic review and meta-analysis of published studies to investigate the effects of increased fluoride exposure and delayed neurobiological development.

Results: The standardized weighted mean difference in IQ score between exposed and reference populations was -0.45 (95% confidence interval: -0.56, -0.35) using a random effects model. Thus, children in high-fluoride areas had significantly lower IQ scores than those who lived in low-fluoride areas. (Italics mine.) Subgroup and sensitivity analyses also indicated inverse associations, although the substantial heterogeneity did not appear to decrease.

Conclusions: The results support the possibility of an adverse effect of high fluoride exposure on children’s neurodevelopment. Future research should include detailed individual-level information on prenatal exposure, neurobehavioral performance, and covariates for adjustment.

Before your eyes glaze over, let’s look at what this all means. Stay with me!

A meta-analysis is a study of a whole slew of studies to chart big-picture information; in this case, the researchers chose 27 studies performed through 2011, including several in the China National Knowledge Infrastructure database, since a significant number of studies on fluoride neurotoxicity have only been published there (interesting, isn’t it, that these studies have never been picked up here). They made sure to correct for bias using some standard analytical methods, found ways to make sure that they were comparing apples with apples, in terms of the way the information was gathered, and pretty much got their ducks in a row.

So when these careful scientists say that children in high-fluoride areas show “significantly lower IQ scores” than kids in low-fluoride areas, that’s a big deal.

OK, you say, but how do you know that my children are exposed to high levels of fluoride? Here’s what I’d look for:

• Do you live in a city or county that fluoridates its water? If you or your family drinks, cooks in, washes lettuce for salads in fluoridated water, you’re getting it.
• Do you eat out? If you live in a fluoridated area, you can be sure that restaurants are likely to be using tap water for food preparation.
• Do you buy processed foods? Chances are good that the manufacturer used fluoridated water to prepare them. That means soda, juice, sports drinks, bottled teas, even beer, has a high probability of having fluoride in it.
• A side note on tea: tea leaves are a natural source of fluoride, since the tea plant pulls fluoride up from the soil and concentrates it in the leaves. Don’t stop drinking tea if you enjoy it, but just be aware that it’s a fluoride source (organic or not).
• Do you use fluoridated toothpaste? You may be thorough about rinsing your mouth (with fluoridated water?), but it’s widely known that young children often swallow small amounts of that minty-fresh paste. Look at the warning label on the side of the package, the part where it instructs you not to swallow the stuff.
• Do you and your family drink bottled water? Depending on where it’s from, it may or not have fluoride in it, so check carefully. Some bottled waters even add fluoride as a supposed benefit!
• And many pesticides and industrial processes have fluoride. If you were looking for another reason to never use Teflon, you can add the fluoride it leaches into foods cooked in it.

So you can see that it’s not all that hard to get a whole lot of fluoride over the course of daily living. Of course, if you’re reading this blog, you probably already avoid fluoride anyway. But if you’ve run across this in a random search, think about taking better care of yourself and your children by:

• Dump the Teflon. Period.
• Invest in a high-end water filter. This isn’t as easy as it sounds; fluoride, and its cousin, fluorine, used to “improve” municipal and county water supplies, are very hard to remove completely. So your best bet is at least reducing it. Consider a reverse osmosis unit for at least your kitchen water supply. My husband and I got a three-stage Doulton filter; one of the three filters in it is a fluoride-reduction unit. Don’t ever think that the “flavor improving” filters that screw on your faucet offer any safety benefits; you need to invest in this, and replace the filters on a regular schedule.
• Don’t buy bottled reconstituted beverages. Make your own juices from fresh fruit. Make your tea and coffee with filtered water.
• Don’t cook with fluoridated water. Use water from that wonderful filter you’ve gotten (and in the meantime, scout around for a store that will sell you water filtered by reverse osmosis; many communities seem to have these. Some natural foods stores have walk-up units where you can buy water for small change; however, read the information carefully to be sure that it’s a good filtration unit and that it’s properly maintained. Talk to the store manager if you have questions.
• And for goodness’ sake, don’t buy or use fluoridated products! That means toothpaste, mouthwashes, fluoride-containing bottled water, etc.