In the 2nd study that shows correlation between fluoride and lower IQ in children, the water had twice as much fluoride as the recommended amount in the US (1.5 mg/L vs 0.7 mg/L).
The only reason for lack of concrete statements on the 0.7 level was a lack of data, owing largely to US political culture (1.5 is the World Health Organization 'safe' limit). Not long ago fluoride stuff was considered a 'conspiracy theory' which greatly deters meaningful scientific research on the topic. This is in part because of social reasons (most people don't want to be perceived as 'fringe') and in part because it results in funding for such research drying up. For that matter even IQ studies themselves are borderline given the US political culture.
So for instance of the 19 low risk-of-bias studies, exactly 0 came from the US. 10 were in China, 3 were in Mexico, 2 in Canada, 3 in India, and 1 in Iran. 18 of those 19 studies found a significant reduction in IQ that corresponds strongly with increases in fluoride (the outlier was in Mexico). With the current administration we'll certainly be seeing funding for such studies in the US and so there should be much more high quality data on the 0.7 level forthcoming. But in general this is a major problem that needs solving. Exploring the breadths of science, including the fringes, should not require an activist political administration.
This might have been a viable argument a decade ago because these rules were implicit and not explicit. But as of 2022 they've become explicit. [1] IQ is distributed dramatically differently in different groups, which makes it difficult to meaningfully study in the US because, as Nature now puts it, "Although academic freedom is fundamental, it is not unbounded... Science has for too long been complicit in perpetuating structural inequalities and discrimination in society..."
This is why meaningful studies on IQ are basically dead in the US and similarly why we were one of last countries to confirm the absolutely critical reversal of the Flynn Effect. I think the political tide started to turn really hard after the decades long Minnesota Transracial Adoption Study ended up definitively proving the opposite of what it intended. [2]
Most working in the field in the US are doing so only due to an effort to undermine it, not study it. Otherwise - they aren't getting published, at least not by the traditionally prestigious journals. Here [1] is a search in reverse chronological order from Nature for studies with the terms IQ and intelligence. The exact demarcation mark is difficult to find, but I do think 1996 is a reasonable indicator. In any case the difference is plainly visible.
I particularly like their trend of publishing editorials with ledes like, "We are leading Nature on a journey to help decolonize research and forge a path towards restorative justice and reconciliation." How can that not make you cringe? People are going to look back at this as the equal but opposite of phrenology. Or perhaps we've had our own Al-Ghazali [2] moment and people will look back at this era as an inflection point in science shifting from one culture to another.
So the problem isn't that the science is being done, it's that the results are challenging conclusions you've already drawn? At least we're clear on what the issue is. The work I'm talking about has nothing about "decolonization" in it, but lots on GWAS and population stratification statistics.
On the contrary, I think the one and only thing that really enabled such widespread advances in science over the past few centuries was the same thing that initially enabled such for the Greeks - people were able to pursue things with near to no limitations, no taboo, no dogma. And it seems that perhaps such things are inherently liminal in nature. The Greeks would then go to on to execute perhaps the greatest thinker in humanity's history for wrongthink, and we ourselves are already well into the times of where not only is there taboo and dogma, but it's even overtly stated.
When you get into population stratification issues you're already again flirting with taboo depending on what is being studied. So yeah - low sample sized, poorly controlled, correlation exclusive GWAS studies are the gold standard in genetics publications. I'm so completely surprised that such, alongside the rusty hacksaw that's CRISPR, failed to live up to even a zillionth of their 'potential'.
Any characteristic being studied whose presence or absence would be seen as socially negative sense is going to be walking a very fine line if it turns out to be associated (or not) with certain subgroups because then you're right back to, in Nature's terms "[being] complicit in perpetuating structural inequalities and discrimination in society."
There are natural experiments where the correlation between IQ and lower amounts of fluoride can be studied. For example in Israel, until 2014, the fluoride level was 0.8-1.0 mg/L depending on the region but starting in 2014 water is no longer fluoridated (naturally occurring fluoride level is in the 0.1-0.3 mg/L range for the vast majority of the population) so the data should be there, it's just a matter of collecting it. Some countries can provide data for the opposite natural experiment (adding fluoride in recent years).
To me, using the 1.5 mg/L doesn't tell anything about lower levels but it does make me interested in seeing such study whereas before I'd have just dismissed it.
