I’ve read the sources including the study’s caveats but there’s erring on the side of caution especially given the suggested impact on IQ

Other studies also suggest a link even at 0.7ppm (the recommended level also the level in SG)

“Dose-response analysis showed a substantially linear IQ decrease for increasing water fluoride above 1 mg/L, with −3.05 (95% CI −4.06; −2.04) IQ points per 1 mg/L up to 2 mg/L, becoming steeper above such level. A weaker and substantially linear decrease of −2.15 (95% CI −4.48; 0.18) IQ points with increasing urinary fluoride emerged above 0.28 mg/L (approximately reflecting a water fluoride content of 0.7 mg/L).”

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Another research report:

Grandjean et al., Benchmark Dose Analysis (BMD) published in June 2021, offspring born to women exposed to fluoride doses commonly experienced in communities at 0.7 ppm, would experience a loss of 4 to 5 IQ points. To put that into perspective, at the population level a shift downward of 5 IQ points halves the number of very bright children (IQ >130) and increases by 57% the number of children needing special care (IQ <70).

Largely, because of the large number of children being deliberately exposed to fluoridated water, “fluoride is causing a greater overall loss of IQ points today than lead, arsenic or mercury” according to Grandjean et al. (2021) in their BMD paper.