Too much of anything will do you harm, yet this does not automatically suggest that beneath a certain level, exposure cannot be beneficial. Any medicine, mineral or vitamin can go from beneficial to toxic if you have enough of it.
Fluoride is no different.
Anti-fluoridation advocates list favoured papers that find links between fluoride exposure and reduced IQ, such as FAN. However, in the case of 37 papers listed by FAN, only 2 look at populations with fluoridation concentrations within the range recommended by the WHO. The rest are more than 2 to 3 times this level!
“Many cross-sectional studies showed that fluoride concentration in drinking water in this area [Hulunbuir City, Inner Mongolia, China] had been higher than the upper limit of 1 mg/L prescribed in Chinese Standards for Drinking Water Quality for a long period. Meanwhile, studies related to fluoride exposure in drinking water have found large number of children accompanied by dental fluorosis in this region.”
So, while the fluoride levels were lower around the study period, this has not always been the case, which is also evident in the high rates of dental fluorosis which couples with high fluoride exposure to tooth development prior to eruption.
Li et al 2009 also notes the variety of water sources in the region, including brick tea, which accounts for a wide range of fluoride exposure.
FAN themselves acknowledge the weaknesses of the various studies that they reference… only to go onto emphasise that, because they have references, all of which find some relationship and others have also suggested a relationship, there must be one!
Yes; at much higher levels of fluoride exposure!
Note what is done here; they correctly illustrate a relationship at very high levels of fluoride exposure, include a couple lower levels, which in truth DO NOT find a relationship to low level fluoride and reduced IQ, then make a small accommodation to the weakness of the approach, followed by appeals of authority of reputable scientific bodies – which are not, in themselves making the claim that fluoridation at recommended levels is a risk to intelligence.
In short, the claim of fluoridation at WHO recommended levels adversely affecting IQ IS NOT being made, but merely alluded to through overreaching and doubt-mongering. “If in doubt, leave fluoride out” or so the anti-fluoridation advocate will say, but obviously it is NOT made on reasonable doubt.
Finally, it’s worth noting that all the studies come from developing nations, which will not have the same health controls and safety practices as is the case carried out in countries such as Australia, the US or the UK. Places like China, India, Iran and Mexico are very likely to have compounding factors.
If there is a risk to IQ from WHO recommended fluoridation levels, an analysis in places like Australia would show it. My simple look at publicly available data failed to find children struggling in fluoridated areas.
The anti-fluoridation rebuttal page now has 14 replies to different debunked anti-fluoridation claims! Each of these has a hotlink to twitter and facebook so that you can quickly post a reply, with a link to further details, in defence of evidence and sound logic.