There are references to some extremely thought provoking papers on the impact of fluoride in this site called fluoride alert.
Given the potential risks of the combination of increased fluoride intake and low iodine, and the growing apparent list of negative health effects of fluoride especially were iodine is low, including on the most fundamental human health issues such as early development and IQ, versus the only claimed upside possible of lowering of carries in the young (maybe at the expense of more brittle bones ? ? ? etc), I increasingly believe on a risk reward basis that the decision to fluoridate water should now be revisited.
http://fluoridealert.org/studies/thyroid01/
Abstract (I recommend you visit the site and particularly the above section; you too may want to have a silent scream)
"Fluoride Exposure Aggravates the Impact of Iodine Deficiency
A consistent body of animal and human research shows that fluoride exposure worsens the impact of an iodine deficiency. Iodine is the basic building block of the T3 and T4 hormones and thus an adequate iodine intake is essential for the proper functioning of the thyroid gland. When iodine intake is inadequate during infancy and early childhood, the child’s brain can suffer permanent damage, including mental retardation.
Fluoride, Low Iodine, & IQ — Human Studies
In China, researchers have repeatedly found that an iodine deficiency coupled with fluoride exposure produces a significantly more damaging effect on neurological development than iodine deficiency alone. In the first study to investigate the issue, Ren reported that:
“From the results it is evident that
disrupted child intellectual development is among the effects on the human body from a harmful environment containing both high fluoride and low iodine, and this disruption is clearly much more serious than the effects of iodine deficiency alone.”
SOURCE: Ren D, et al. (1989). A study of the intellectual ability of 8-14 year-old children in high fluoride, low iodine areas. Chinese Journal of Control of Endemic Diseases 4(4):251 (republished in Fluoride 2008; 41:319-20). [See study]
Since Ren’s study, other research teams have reported the same result. In 1991, a UNICEF-funded study concluded that fluoride levels of just 0.9 ppm (less than the level added to many water supplies for fluoridation) were sufficient to worsen the effects of iodine deficiency.
The authors found that, when compared to children with iodine deficiency in a low-fluoride area, the children with iodine deficiency in the 0.9 ppm area had increased TSH levels, reduced T3, reduced intelligence, retarded bone development, and reduced hearing. According to the authors:
“Statistically significant differences existed between these areas, suggesting that a low iodine intake coupled with high fluoride intake exacerbates the central nervous lesions and the somatic developmental disturbance of iodine deficiency.”
SOURCE: Lin Fa-Fu; et al (1991). The relationship of a low-iodine and high-fluoride environment to subclinical cretinism in Xinjiang. Endemic Disease Bulletin 6(2):62-67 (republished in Iodine Deficiency Disorder Newsletter Vol. 7(3):24-25). [See study]" . . . MORE