Again, the point you seem determined to miss is that the premise of your thread title is grossly misleading.
We all know that virtually anything ingested in over-abundance will likely cause negative consequences, but your title implies a blanket indictment of an agent with proven dental caries reducing activity when used in moderation, a mere 1.0 part per million.
You obfuscate with a statistic (from a government bureaucracy) that 4% of school age children have severe fluorosis. Well, the images below demonstrate severe fluorosis.
I dare say that 1 in 25 school age children in the general population do not look anywhere near this presentation.
It wouldn't be the first time Big Government flunky bureaucrats, such as those at the US Centers for Disease Control, were wrong.
Consider the history of how the caries reducing action of fluoride was discovered:
A Classic Epidemiological Study
Involves the demonstration of the caries inhibitory properties of fluoridated water. Began with the study of "Colorado Brown Stain" by Frederick S. McKay in 1908. Stain was found only in long term residents of Colorado Springs. The etiological agent, then, was something in the environment which was active during the formation of the teeth. The water supply from deep artesian wells was the only experience shared by all, thus the agent responsible for the dental mottling was some common constituent of the community water supply. Yet a priori this explanation seemed absurd. repeated chemical analyses, covering all known elements found in the drinking water failed to reveal anything common to all of the waters associated with mottled enamel.
Oakley, Idaho, in 1925 was the first community to alter domestic water to improve dental health by changing their source of water so as to free themselves of mottling.
In 1931 McKay sent Oakley water samples to H. V. Churchill at ALCOA where new spectrographic methods of analysis revealed naturally occurring fluoride present up to 14 parts-per-million. The immediate reaction of the scientific community was a number of studies to determine whether fluoride in the amounts normally found in the water supply were injurious to human health. But McKay had noticed in 1928 that the same water which produced mottled enamel also seemed to reduce the prevalence of dental caries. McKay and H. Trendley Dean demonstrated the fact that fluoride ingestion could be adjusted to an optimal intake with hazard to the individual at small expense. The caries inhibitory effect of fluoridated water is discernible in individuals as old as 45 years.
Dean had shown that mottling was manifest in a wide range of degrees, from fine, lacy markings almost invisible to extreme hypoplasia in which enamel was pitted, stained and highly friable. He made a six grade Index of Dental Fluorosis. His studies showed that there was definite relationship between the prevalence of fluorosis and previous studies on prevalence of caries. With this presumptive evidence, a direct test of the hypothesis was designed. Sound conclusions could be reached only in those communities with a common water supply from the same source to all residents, without alteration during the lifetime of the people to be examined with a stable fluoride level over a period long enough to establish and define range of fluoridation.
Two cities with 1.7-1.8 ppm fluoride and two with 0.2 ppm fluoride were selected. Examinations of children aged 12-14 who were lifetime residents showed that the prevalence of dental caries was about twice as high in the 0.2 ppm fluoride cities as in was in the 1.7-1.8 ppm cities. The conclusion stated that if marked caries inhibitory influence were operative at concentrations as low as minimal threshold of endemic fluorosis mottling (i.e., 1.0 ppm) the findings would be important.
Subsequent studies did show that strikingly low dental caries prevalence was associated with 1.0 ppm fluoride with only sporadic instances of the mildest forms of dental fluorosis of no practical esthetic significance. Controlled artificial fluoridation of municipal water supplies was thus begun in 1945 in Grand Rapids, Michigan.