We all take for granted that adding fluoride to our drinking water is a safe and effective way to prevent cavities, but just how much do we know about the side effects of water fluoridation?
“The evidence shows that it is effective and safe, and has made a wonderful contribution to the health of kids in North America,” says Dr. James Leake, head of Community Dentistry at U of T. “In 1959, 89 per cent of 13 year old children examined in Toronto had had one or more cavities in their life.” Toronto began fluoridating its water in 1963. “By 2000, only 39 per cent of 13 year olds had had one or more, so 61 per cent of all children had never had a cavity. It’s hard not to appreciate what a difference fluoridation has made.”
Thousands of other such studies that have been done all over the world since water fluoridation began in 1945. Dr. Leake pointed to a study done in 2000 by the University of York in the UK. “They did the best and the most comprehensive review of all the world’s literature and came to the conclusion that it was both effective, and the doses being provided are safe.”
But not all dentists and health professionals agree on the benefits of fluoride. A sharp divide is emerging between those for and against water fluoridation.
“I used to teach dental students that fluoridation was the most inexpensive way to deliver fluoride to everyone in the community,” said Dr. Hardy Limeback, head of Preventive Dentistry at U of T. “But, after thoroughly reviewing the literature, I discovered that there was little, if any, benefit from swallowing fluoride, and that there were significant risks from the long-term ingestion of fluoridated water.”
When ingested, as opposed to applied directly to the teeth as in a fluoride treatment or with toothpaste, fluoride accumulates in the body, and according to Dr. Limeback, can cause health problems. “There has been a huge increase in dental fluorosis in Toronto,” he says. Dental fluorosis is a condition caused by an excess of fluoride exposure, which can range from faint white markings to unsightly brown stains. “This condition is the first sign that the body has been over-dosed with fluoride,” said Dr. Limeback. About 12 per cent of the population of Toronto has dental fluorosis, according to both Dr. Leake and Dr. Limeback.
“Symptoms of too much fluoride accumulation over a long time include the early stages of skeletal fluorosis (joint pain), an increased risk for bone fracture, and thyroid dysfunction,” said Dr. Limeback. Other studies suggest links between fluoridated water and cancer, genetic damage, neurological impairment, and early menstruation in girls.
“Many researchers have published that the main effect of fluoride is a topical one, and that there is little benefit to ingesting fluoride,” said Dr. Limeback. “The Centre for Disease Control in Atlanta has acknowledged this in their recent report, stating that ‘The laboratory research that has led to the better understanding of how fluoride prevents dental caries indicates that fluoride’s effect is…topical and that the effect depends on fluoride being in the right amount and in the right place at the right time.”
A Brita filter does not remove fluoride from drinking water-the only way to remove fluoride is through distillation, or by the use of ion-exchange columns.
Of particular concern for opponents of fluoridation are the chemicals used to fluoridate tap water. More than 90 per cent of the tap water in North America is fluoridated using hexafluorosilicic acid and its sodium salts. “These are waste products obtained from the pollution scrubbers of the phosphate fertilizer industry,” said Dr. Limeback. “They contain trace amounts of arsenic, lead, and other toxic chemicals.”
An official from the City of Toronto Water and Wastewater Services confirmed that hexafluorosilicic acid is used, but was uncertain of the precise composition of the mixture-which is not produced in Canada but in the United States. The distributor for Toronto’s water fluoridation chemicals is LCI Ltd., located in Jacksonville, Florida. Gustavo Navar, senior chemical engineer for LCI Ltd, confirmed that the hexafluorosilicic acid used in water treatment is obtained from phosphate fertilizer companies, which produce the compound as a by-product from the production of phosphoric acid. When asked about the precise composition of the mixture, Navar said: “These are not 100 per cent pure chemicals-I’m sure there are traces of arsenic in there.” He added, “The material meets Canadian and American standards for products to be used in water treatments.” Further information about the company that produces the mixture was not forthcoming.
“Repeated analysis of this toxic waste product shows it to be contaminated with up to 2 per cent by weight with toxic, carcinogenic trace elements such as radium and arsenic,” Dr. Limeback said. “Even when the liquid is diluted and trickled into the drinking water, it adds between 0.5 to 1.4 parts per billion arsenic to the drinking water, which, according to the National Academies of Sciences in the US, increases the cancer risk from between 1 in 10,000 to 1 in 5,000. That means that it is possible that up to 1,000 cancers in the GTA area can be attributed to the drinking water fluoridation chemicals.”
Two published studies have shown that silicofluorides significantly raise blood lead levels in children. One study found higher rates of violent crime, hyperactivity, heart disease, and drug abuse in communities using silicofluorides-all conditions known to be linked to lead and other heavy metals.
“These chemicals were never tested for safe use on humans,” said Dr. Limeback. Clinical trials were performed on sodium fluoride, which was originally used when water fluoridation began in 1945. Those studies found no adverse health effects. However, communities began to switch to silicofluorides in 1947, “without any animal or human tests having been done.”
“No one has explained to me why governments would allow toxic waste to be trickled into our drinking water but the conclusion is obvious-large corporations save enormous amounts of money by selling the toxic waste to cities rather than paying large sums of money to clean it up and dispose of it properly,” said Dr. Limeback. “Conservative governments won’t push corporations to clean the fluoridation chemicals.”
Dr. Limeback is not alone in his public opposition to water fluoridation.
Dr. Charles Gordon Heyd, past president of the American Medical Association, said in a July 2000 letter concerning the proposal to fluoridate the water in Palo Alto, California: “I am appalled at the prospect of using water as a vehicle for drugs. Fluoride is a corrosive poison that will produce serious effects in a long-range basis. Any attempt to use fluoride in this way is deplorable.”
On July 7, 1997, 1,500 Environmental Protection Agency (EPA) scientists, engineers and lawyers who assess the scientific data for the Safe Drinking Water Act standards and other EPA regulations went on record against the practice of adding fluoride to public drinking water. “It is our hope that our co-sponsorship of the Safe Drinking Water Initiative to prohibit fluoridation will have a beneficial effect on the health and welfare of all…by helping to keep their water free of a chemical substance for which there is substantial evidence of adverse health effects, and, contrary to public perception, virtually no evidence of significant benefits. We conclude that the health and welfare of the public is not served by the addition of this substance to the public water supply.”
Dr. John Colquohoun, once Auckland, New Zealand’s Principal Dental Officer and former fluoridation advocate, initially dismissed studies that showed that dental decay did not significantly decrease in fluoridated communities compared to non-fluoridated communities. He later said in a 1997 report, “I now realize that what my colleagues and I were doing was what the history of science shows all professionals do when their pet theory is confronted by disconcerting new evidence: they bend over backwards to explain away the new evidence.”
Despite mounting evidence shedding doubt on the safety of water fluoridation, Dr. Limeback has found it difficult to present his case. “It has been hard defending my views. I have been ridiculed and I have suffered character assassination. I have been accused of lying, misrepresenting scientific evidence, citing literature selectively and quoting only so-called ‘junk’ science to support my views. I have been ridiculed by dentists and politicians at public hearings, and I have been formally attacked by other scientists in the field. The most opposition has been from the public health sector. That’s understandable. The public health officials do not want to lose face. They may even fear litigation.
“To be honest, my career has suffered so much, that I regret ever coming forward at all in the first place-I wish I had just kept my mouth shut.”
Dr. Limeback, however, is not the only individual who has found himself challenged on water fluoridation.
In 1992 Dr. William L. Marcus, the Senior Science Advisor to the EPA’s Office of Drinking Water, was fired after calling for a national review of water fluoridation. The EPA stated that he was fired due to professional difficulties; Marcus claimed that he was fired for his views on fluoride. A judge ordered him reinstated to his job, concluding that he was fired “because he publicly questioned and opposed the EPA’s policy.”
In 1994, Dr. Phyllis Mullenix, the head of Toxicology at the Forsyth Dental Center in Boston was fired after her publication of a study that found fluoride to be a central nervous system toxin, causing a reduction in IQ in children. Forsyth claimed she was dismissed because her work was not “dentally related.”
“Public health scientists have, for over 50 years, used selective literature citation to push water fluoridation,” said Dr. Limeback. “It is the responsibility of the public health authorities to prove that fluoridation is absolutely safe. There are warning labels on toothpaste in the US that recommend you contact a poison control center or a physician if you ingest more that what’s used for tooth brushing. That means if you ingest the equivalent of about 0.5 L fluoridated drinking water, you’ve just been poisoned with fluoride, according to the toothpaste warning label.”
When asked why governments would advocate fluoridation, Dr. Limeback replied: “To appear to be ‘helping the poor’ and at the same time trying to reduce dental care costs-poor people have a higher rate of dental decay. More children on social services requiring dental care are being turned away by dentists who can no longer afford to provide dental care below cost.”
Dr. Leake, in favour of fluoridation, echoed Dr. Limeback’s concern for the dental health of the poor. “About a third of children in Toronto live in poverty,” said Dr. Leake. “Public health is aware of the needs of those kids, and need to maintain fluoride levels for children who wouldn’t get the benefits from fluoride in any other way.”
“I think it’s an absolute necessity to establish a universal dental health care plan,” said Dr. Leake, but added that the costs of such a program would far exceed the current expenditures on water fluoridation.
“Most of Europe has rejected fluoridation,” said Dr. Limeback. “So has Japan. It’s time that North America looked really carefully at the practice of fluoridation. The benefits no longer outweigh the risks. I would like to see fluoridation stopped and the money spent providing better preventive care to targeted groups of the population.”
