e face of it, it would seem that rats drinking 30 ppm fluoride in water are receiving roughly 30 times more fluoride than humans drinking fluoridated water (1 ppm). However, upon closer inspection, this assumption does not hold true.
Why? Because rats are more resistant to fluoride toxicity than humans. The increased resistance of rats to fluoride toxicity seems to stem from the ‘reduced intestinal absorption’ of fluoride found in the rat. In other words, when rats ingest fluoride, less of the ingested fluoride actually makes it into their bloodstream. Because of this, rats are known to have far lower levels of fluoride in their blood than humans when consuming the same level of fluoride in water.
Indeed, while Guan and colleagues do not provide data on the level of fluoride in the rats’ blood, the blood levels normally found in rats drinking ~30 ppm fluoride in water (range = ~76-143 ppb) are actually overlapped and exceeded on a chronic basis by a portion of the human population (particularly those with kidney disease) living in fluoridated, and even unfluoridated, areas.
Moreover, the lower range of the levels normally found in rat’s blood drinking 30 ppm fluoride are also reached by young children (albeit for short duration) after ingesting fluoridated toothpaste and/or fluoride supplements. And, on a less frequent basis, young children’s blood can temporarily be infused with fluoride levels which far surpass (by up to a factor of 10) the levels found in rats drinking 30 ppm. The occasion? Use of high concentration acidulated fluoride gels in the dental chair.
Thus, for reasons that should become even more apparent in future Science-Watch bulletins, any damage found in rats drinking water with just 30 ppm fluoride should be taken very seriously.
A Tale of Two Worlds?
Finally, it is heartening to note that the Guan team has apparently not had any problems securing financial support to continue their research. Their research has consistently received ample funds from branches of the Chinese Government and China’s National Natural Science Foundation.
I mention this fact because it stands in rather stark contrast to the experience of US scientists who have also attempted to investigate fluoride’s impact on the brain.
The most notable example, of course, is the experience of Dr. Phyllis Mullenix, former chair of Toxicology at the prestigious Dental Forsythe Center. Ever since publishing her findings (in 1995) indicating neurotoxic effects of fluoride in rats, Mullenix was not only fired from her job, she has been unable to receive any money from government sources to continue her research. (Chris Bryson discusses Dr. Mullenix’s experience in great detail in his new book The Fluoride Deception from Seven Stories Press, May 2004).
Hopefully, however, with more and more research on fluoride and brain coming in from overseas and being published in western journals, some independent US scientists will become emboldened to start investigating the issue themselves, and will find ways of securing the funds to do so.
In the mean time, it is encouraging to know that there are scientists such as Dr. Guan in China and Sweden, actively researching fluoride’s neurotoxicity and publishing their findings. They are no doubt well ahead of the curve.
ADDENDUM: The Growing Body of Evidence that Fluoride Damages the Brain
Included below are excerpts from recent studies investigating fluoride’s impact onthe brain.
The studies are organized into 3 categories:
- Animal Studies from Dr. Guan & Colleagues
- Animal Studies from other research teams
- HUMAN Studies
1) Animal Studies from Dr. Guan & Colleagues
“Recently, we have detected the alterations of nicotinic acetylcholine receptors (nAChRs) in rat brains and PC12 cells affected by fluoride toxicity… [O]xidative stress, including protein oxidation of the receptors and lipid peroxidation in cellular membrane, might be a mechanism of the deficit of the receptors.”
SOURCE: Shan KR, Qi XL, Long YG, Wang YN, Nordberg A, Guan ZZ. (2004). Decreased nicotinic receptors in PC12 cells and rat brains inf