What I'm interested in in this investigation is the cerebral (brain, etc.) effects of exposure to fluoride in drinking water.
Begin reading data here.
Chinese scientists have found that the greater the exposure to fluoride in drinking water, the lower the IQ scores of children.
The IQ scores in both males and females declined with increasing fluoride exposure.
There are, in addition to deleterious intelligence-related effects, deleterious psychiatric effects as well, owing to drinking-water fluoride exposure.
Spittle (1994) reviewed surveys and case reports of individuals exposed occupationally or therapeutically to fluoride and concluded there was suggestive evidence that fluoride could be associated with cerebral impairment. A synopsis of 12 case reports of fluoride-exposed people of all ages showed common sequelae of lethargy, weakness, and impaired ability to concentrate regardless of the route of exposure. In half the cases, memory problems were also reported. (...) Spittle also noted the likelihood of fluoride interfering with the basic cellular energy sources used by the brain through the formation of aluminum fluorides (Jope 1988) and subsequent effects on G proteins.
reaction times and visuospatial abilities can be impaired. These changes would act to reduce the tested IQ scores. (...) Extended reaction times have been associated with impaired function of the prefrontal lobes, a behavioral change not directly tied to alterations in IQ (Winterer and Goldman 2003). Because almost all IQ tests are “time-restricted,” slow reaction times would impair measured performance.
As for fluoridation's link to Alzheimer's disease/dementia:
(...) In a study of more than 3,500 French men and women above the age of 65 (Jacqmin et al. 1994), a significant decrease in cognitive abilities was found when their drinking water contained calcium, aluminum, and fluorine. Only aluminum showed any relation to cognitive impairment and that depended on the pH of the drinking water being below 7.3. Curiously, at higher pH values, a favorable effect on cognitive actions was found. In recent work with animals, aluminum-induced behavioral changes similar to those found in human dementia, as well as correlated histological changes in animals’ brains, were found (Miu et al. 2003). Active research continues at the cellular level on the neural mechanisms disturbed by aluminum (Becaria et al. 2003; Millan-Plano et al. 2003). (...) fluoride produces alterations in phospholipid metabolism and/or reductions in the biological energy available for normal brain functions (...) possibility exists that chronic exposure to AlFx can produce aluminum inclusions with blood vessels as well as in their intima and adventitia. The aluminum deposits inside the vessels and those attached to the intima could cause turbulence in the blood flow and reduced transfer of glucose and O2 to the intercellular fluids. Finally histopathological changes similar to those traditionally associated with Alzheimer’s disease in people have been seen in rats chronically exposed to AlF (Varner et al. 1998).
This is frightening.
It's also known that fluoride exposure can actually harm the teeth as opposed to protecting them, making them turn brownish and brittle (dental fluorosis), even making the teeth so brittle as to make filling cavities impossible, thus requiring tooth extraction.
There's also the possibility of deleterious effects on bones (bone fluorosis), as well as many other kinds of negative effects on the body.
Why the hell, then, are we fluoridating our water?
The many negatives far outweigh the one perceived positive.
Besides, it eats up our tax dollars.
If your community fluoridates the water supply, be advised of the contraindications of doing so. You may push local government to end the practice, if you wish. Start a citizen's movement. A "Tea Party" type movement, you know...
Myself, I, for many years, have drank very little tap water, preferring soft drinks, bottled spring water and Brita-filtered water (I just hope the filter actually binds the fluoride, removing it from the water, along with the terrible chlorine smell and taste).
Note to Leftists: If you don't want the state to decide what will be done with your body (eg. in the case of whether to allow or ban abortion), then you ought to be opposed to fluoridation, at least on the grounds that it shouldn't be imposed onto people who don't want it.