Kind of hesitant to jump back into the fluoride food fight, but Living On Earth went there first with an attack on fluoridation. (Obligatory disclaimer: I love LOE and listen to their podcasts religiously, but per the Blogger Commandments, I'm now highlighting them for the purposes of ankle-biting.)
The fluoride segment has a number of problems but let's start with the main one - the failure to wrestle with scientific consensus positions that water fluoridation is effective and safe (update: should describe the consensus as "effective, and safe enough to be highly recommended"). To be harsh about it, you could easily find a similar post on a climate denialist website - begin with a token mention of the mainstream position and then highlight something published recently that you present as an important contradiction. So what LOE failed to do was to explore the consensus and how it formed. They failed to wrestle with their opposition to the consensus - they might say they don't have a position, they're just reporting out on recent science that calls the consensus into question, but that's cherrypicking by excluding the science that reinforces the consensus. Finally they fail to wrestle with how non-experts should handle scientific consensus.
My perspective is that the non-expert's first job is to understand the consensus, including what is the consensus on the level of confidence in their various conclusions. That doesn't mean things always stay the same, but that change is an internal process - non-expert cherrypicking of outlier studies that happen all the time isn't a good way to predict a change.
What LOE focuses on is effectiveness of fluoridation and effect on IQ. For effectiveness it references a meta-analysis and says
The Cochrane Collaboration, a global network of doctors and researchers who analyze science to improve public health, suggests the evidence is not so clear. The group found earlier this year that only three studies since 1975 have established credible links between fluoridated water and cavity prevention. Again, Dr. Peckham.
PECKHAM: Their main conclusions were that there was no evidence to suggest that it reduced inequalities in dental health, that there was no evidence to support that it had a positive effect on adult teeth, and that there was no evidence to suggest that if you stopped water fluoridation, levels of decay would increase.LOE doesn't provide a direct link to the Cochrane, just to a Newsweek article about it. Did LOE actually read it? When you dig out the article you find there were more than three studies. Cochrane decided to exclude other studies because they compared fluoridated and non-fluoridated communities, not before/after studies of places that began fluoridation. This will become ironic about about four paragraphs from now. Cochrane says this:
Our review found that water fluoridation is effective at reducing levels of tooth decay among children. The introduction of water fluoridation resulted in children having 35% fewer decayed, missing and filled baby teeth and 26% fewer decayed, missing and filled permanent teeth. We also found that fluoridation led to a 15% increase in children with no decay in their baby teeth and a 14% increase in children with no decay in their permanent teeth. These results are based predominantly on old studies and may not be applicable today.A little different from what was reported out on LOE. In particular, those of us familiar with Roger Pielke Jr.'s "work" on damages from storm events know the distinction between detection and attribution. Lots of noise doesn't mean there is no signal. And it's flatly wrong for LOE to report out insufficient evidence as "no evidence". Finally, a reality check - we know lots of children receive inadequate dental care at home and don't get to the dentist enough. These kids aren't that different from those prior to 1975 when fluoride toothpaste and dental office fluoridation became common.
Within the ‘before and after’ studies we were looking for, we did not find any on the benefits of fluoridated water for adults. We found insufficient information about the effects of stopping water fluoridation. We found insufficient information to determine whether fluoridation reduces differences in tooth decay levels between children from poorer and more affluent backgrounds.
So, IQ next from LOE:
GRANDJEAN: We looked at more than 20 studies from China where they had compared children exposed to high fluoride content in the water and low. And on the average, the difference in performance among those kids was seven IQ points. That’s a sizable difference. And obviously some of the kids have been exposed to substantial fluoride concentrations in water, some of them were just a little bit above what’s common in this country and, therefore, I find that evidence very worrisome, and we need to follow up and determine if there is any risk in regard to fluoride exposure under US conditions.The China studies examined fluoride effects by, maybe you guessed it, comparing communities exposed to fluoride with communities not exposed, the same type of study Cochrane excluded as inadequate. Some of the exposure was many times the recommended US level. Some of it was also from exposure to coal pollution, and I'll gently suggest those children were dealing with more problems than just fluoride in that case.
Mainly the issue with LOE is cherrypicking. The 2010 Health Canada report, a national level consensus document, found that the Chinese studies it examined were unreliable (see section 9.1.7). The 2014 Dunedin longitudinal study found no neurological effect from fluoride (actually a slight benefit but not statistically significant).
Maybe LOE doesn't know about this research, but that points out the problem of non-experts jumping at the latest scientific blip and ignoring the consensus. There are other flaws in the LOE report and other things I don't really know about, because I'm not an expert, but I think there's a pattern.
Fluoridation and climate change aren't equivalent debates - I'd compare fluoridation more to GMOs where both sides exaggerate and oversimplify, a contrast to climate change where realistic bad scenarios are usually underplayed. My non-expert reading of the scientific consensus is there are some aspects of fluoridation that are still potentially problematic. The way to resolve those issues is through pushing for scientific progress.