Stop fluoridation now: new research on fluoride's brain and thyroid toxicity

Townsend Letter for Doctors and Patients, April, 2005 by Gary Null, Martin Feldman

Several years have passed since we published a three-part article on water fluoridation entitled "The Fluoride Controversy Continues: An Update" in the Townsend Letter (see the December 2002, January 2003 and February/March 2003 issues). Since that time, new research has emerged that offers health-care professionals and patients alike a more thorough understanding of fluoride's adverse effects on the body.

In this article, we will look at the effects of fluoride on two vital aspects of the body's functioning--the central nervous system and brain and the thyroid mechanism--in more depth than we did in our prior article. We will also explore a newly emerging area of research, which shows that xylitol, a natural sugar substitute used in chewing gums and other products, provides consumers with an effective alternative to the fluoridation of public water supply systems in preventing dental cavities.

As we reported previously, approximately 162 million Americans on public water systems were receiving fluoridated water in 2000. (1,2) The US government strongly supports water fluoridation on the grounds that it decreases the rate of dental decay. (3, 4) Yet studies conducted worldwide have failed to validate this claim. In one large study conducted in 1986/87 for example, there was no statistically significant difference in dental decay rates between fluoridated and nonfluoridated cities. (5) Other research has found a decline in the dental caries rate in countries that do not have fluoridated water.

The research also shows that fluoride can have a wide range of negative health effects. Many of these effects were discussed in our previous article, where readers can find a full investigation of the topic and supporting references from the scientific literature. By way of review, the following list summarizes some of the major effects of fluoride on the body. This accounting should raise serious questions in anyone's mind about the practice of adding fluoride--which, in the case of water fluoridation, is a toxic waste product of the aluminum and fertilizer industries--to community water systems:

* Dental fluorosis. The prevalence of dental fluorosis, in which the teeth become permanently stained, brown and mottled due to fluoride exposure, has increased in both fluoridated and nonfluoridated communities in recent decades. (6)

* Skeletal fluorosis. Fluoride that is deposited in the bones and teeth can cause this crippling disorder. Some experts have suggested that while skeletal fluorosis is rarely reported in the US medical literature, cases may go unrecognized due to a lack of knowledge about the disorder among physicians. (7)

* Bone fractures. Studies have found an association between fluoride and the rate of hip fractures among the elderly. (8-10)

* Cancer. Links to fluoridation have been revealed in numerous studies, with one finding that about two-thirds of 36 cancer sites in the body were associated with fluoridated water. (11)

* Enzyme toxicity and genetic damage. Even 1 ppm of fluoride--an amount deemed safe for water fluoridation--can interfere with biological functions such as DNA repair enzyme activity and cause genetic and chromosomal damage. (12, 13)

* Reproductive effects. Fluoride may have negative effects on the male and female reproductive systems, according to several studies. (14-16)

* Pineal gland effects. Fluoride's adverse impact on this gland may interfere with the hormone melatonin, which regulates sleep cycles, the onset of puberty and other functions. (17)

* Elevated blood lead levels. Increased levels of lead in the blood of children have been associated with fluoridated drinking water. High levels of lead, in turn, have been linked to certain health disorders and negative behavioral traits. (18, 19)

Brain effects of fluoride

One growing area of research has examined the effects of fluoride on the central nervous system and brain. Recent studies have found that fluoride is a neurotoxin which can affect cerebral functioning, with some research associating the ingestion of fluoridated water with reduced intelligence. Scientific references in this area from human and animal studies deserve careful consideration from physicians and consumers who want to know how the multiple sources of fluoride we are exposed to--fluoridated water, fluoridated toothpaste, fruit juices and soft drinks, infant foods, and others--may affect such a critical aspect of the body's functioning.

A number of studies on the effect of fluoridated water on children's intelligence come from China, where investigators have compared the Intelligence Quotient (IQ) of young people living in high- and low-fluoride areas. These studies include:

* The mean IQ of 222 children, aged 8 to 13 years, in a high-fluoride village was significantly lower (92.02 [+ or -] 13.00) than that of 290 children in a low-fluoride village (100.41 [+ or -] 13.21). Higher levels of fluoride in drinking water were significantly associated with higher rates of mental retardation (IQ <70) and borderline intelligence (IQ 70-79). The researchers concluded that "drinking water fluoride levels greater than 1.0 mg/L may adversely affect the development of children's intelligence." (20)