[defrost]

The study Developmental Fluoride Neurotoxicity: A Systematic Review and Meta-Analysis [1] (discussed in your link above) has data on drinking water in China.

It includes quotes relavant to the USofA:

    Such circumstances are difficult to find in many industrialized countries, because fluoride concentrations in community water are usually no higher than 1 mg/L, even when fluoride is added to water supplies as a public health measure to reduce tooth decay.

and

    In response to the recommendation of the NRC (2006), the U.S. Department of Health and Human Services (DHHS) and the U.S. EPA recently announced that DHHS is proposing to change the recommended level of fluoride in drinking water to 0.7 mg/L from the currently recommended range of 0.7–1.2 mg/L, and the U.S. EPA is reviewing the maximum amount of fluoride allowed in drinking water, which currently is set at 4.0 mg/L

Note that the U.S. EPA is reviewing the maximum amount of fluoride allowed in drinking water concerns levels naturally occuring and is not a recommendation to add fluoride to US drinking water in excess of 1 mg/litre.

I am unable to find data in that report that supports your assertion.

If you have data you wish to draw eyes to then please quote the numbers and link to the source.

[1] https://ehp.niehs.nih.gov/doi/10.1289/ehp.1104912

[colordrops]

The problem is that it's an EPA recommended dosage, and not regulated nationwide, leading to a large variance in levels. "The fact that fluoridation of water is not regulated nationwide leads to a challenge for individuals interested in generating meaningful data for nationwide databases." [1] In the short list of measurements in the quoted paper, it ranged from almost nothing to 1.5 mg/L, and that's a very small sample. Borden County in Texas has levels above 5.5 mg/L in some areas [2]

[1] https://www.ars.usda.gov/ARSUserFiles/80400525/Articles/jfca...

[2] https://www.beg.utexas.edu/files/content/beg/research/TCEQ_s...

[defrost]

You still have not supported the claim made above that:

> The amounts with measurable cognitive deficits were less that the amounts added to drinking water in the US ...

Your first link ( [1] ) cites a source in Springfield as the maximal value seen (in that report) of 1.5 mg / litre (with no mention of whether that's due to added fluoride or a result of natural fluoride in the groundwater).

Your second link ( [2] ) is about an untreated groundwater source that serves 150 people with:

    Fluoride has been detected between 4 milligrams per liter (mg/L) and 5.57 mg/L from July 2002 to March 2007, which exceeds the maximum contaminant level (MCL) of 4 mg/L as well as the Secondary MCL of 2 mg/L set by the USEPA.

and is titled as a DRAFT FEASIBILITY REPORT looking at the costs of treatment with (for example) :

    Centralized treatment alternatives for arsenic and fluoride removal have been developed and were considered for this report; ...

To summarise; you have claimed but not demonstrated that intentional treatment in the USofA has added fluoride to reach levels that (are assumed | correlated ) caused IQ losses of less than half a point in China.

Your link clearly do not support this, Borden County is untreated and the intent is to look at reducing the high fluoride levels.

[colordrops]

You should re-read the study I linked:

"The average loss in IQ was reported as a standardized weighted mean difference of 0.45, which would be approximately equivalent to seven IQ points for commonly used IQ scores with a standard deviation of 15."

Seven points IQ difference.

Also, if you bother to look at the data in the linked paper, many of the regions with measurable deficits were in the 0.5 to 2 mg/L range, well within typical treatment levels in the US.

[defrost]

Fair point re: IQ - I misread that.

> Also, if you bother to look at the data in the linked paper, ...

Excuse me? Mind the shade please.

> many of the regions with measurable deficits were in the 0.5 to 2 mg/L range

Exactly how many of the 27 studies listed actually had "high" fluoride values in that range?

If you bother to look at the data you might concede it's not "many" by a long shot.

More to the point, in those few studies with low fluoride levels how much was IQ correlated to fall?

The meta study findings were:

    Findings from our meta-analyses of 27 studies published over 22 years suggest an inverse association between high fluoride exposure and children’s intelligence. Children who lived in areas with high fluoride exposure had lower IQ scores than those who lived in low-exposure or control areas.

Note Well: "than those who lived in low-exposure or control areas."

It's a meta study.

It looked at studies with low levels of fluoride AND at studies with high levels of fluoride.

It determined that high levels of fluorine are not good (and that many of the studies had other issues such as lead, arsenic, iodine that had to be dealt with).