They really rule out much more than that: −0.14 is from their worst-case:
Looking at the estimates, they are very small and often not statistically-significantly different from zero. Sometimes the estimates are negative and sometimes positive, but they are always close to zero. If we take the largest negative point estimates (−0.0047, col. 1) and the largest standard error for that specification (0.0045), the 95% confidence interval would be −0.014 to 0.004. We may thus rule out negative effects larger than 0.14 standard deviations in cognitive ability if fluoride is increased by 1 milligram/liter (the level often considered when artificially fluoridating the water).
So that is not the realistic estimate, it is the worst-case after double-cherrypicking both the point estimate and the standard error to reverse p-hack a harm. The two most controlled estimates are actually both positive.
(Meanwhile, any claims of decreases, or that one should take the harms ‘many times over’, is undermined by the other parts like labor income benefiting from fluoridation. Perhaps one should take dental harms more seriously.)
They really rule out much more than that: −0.14 is from their worst-case:
So that is not the realistic estimate, it is the worst-case after double-cherrypicking both the point estimate and the standard error to reverse p-hack a harm. The two most controlled estimates are actually both positive.
(Meanwhile, any claims of decreases, or that one should take the harms ‘many times over’, is undermined by the other parts like labor income benefiting from fluoridation. Perhaps one should take dental harms more seriously.)