Myths That Spark Controversy and Debate
Sixty years ago, Rachel’s hometown, Grand Rapids, Michigan, became the first city in the world to implement fluoridation of the entire water supply, which means that they added more fluoride to the already naturally occurring fluoride in their water source. Grand Rapids paved the way, but thousands of other communities have since added fluoride to their water supplies, with the aim of raising the fluoride level to the optimum amount that will prevent cavities and tooth decay. Two-thirds of the US population lives in a community where the water is fluoridated. However, some believe that this is a cause for concern, not celebration.
The Fluoride Action Network, an organization dedicated to educating people about the dangers of fluoride, offers many arguments against the policy of adding fluoride to water supplies. Among their claims, they note that fluoride has minimal benefit when it is swallowed and that fluoride is not recommended for babies. They propose that fluoride has many risks, including to the brain, thyroid gland and bones. Others make much more alarmist statements, calling fluoride a ‘corrosive poison’. Websites and publications raising concerns about fluoride offer ‘scientific references’ and ‘expert quotes’ that really could cause concern that the fluoride in your water not only doesn’t help you but could actually be hurting you. Let’s review the evidence.
First of all, overwhelming evidence has existed for over sixty years that proves the efficacy of water fluoridation. Some of the best studies come from the early days of fluoridation, because it was easier then to find groups of people who were not exposed to any fluoride sources. In a fifteen-year landmark study from Grand Rapids, Michigan, children who received fluoridated water from birth had 50–63 per cent less tooth decay than children from a nearby city in Michigan who drank non-fluoridated water. A comparison study in Newburgh, New York, found that six- to nine-year-olds had 58 per cent less tooth decay than kids in a nearby city with fluoride-deficient water ten years later, and they had 70 per cent less decay fifteen years later. A huge survey in the United States of almost 40,000 school children found that tooth-decay rates were declining overall (probably because of higher-quality toothpastes, mouthwashes and supplements that all contain fluoride), but even when scientists controlled for all of those other things the kids might be exposed to, kids who had fluoride in their drinking water still had 25 per cent less tooth decay.
The evidence for how well fluoride works is overwhelming. A compilation of the results of 113 studies in 23 countries showed reductions in tooth decay for both baby teeth and adult teeth. People with fluoride in their water had 40–49 per cent less tooth decay in baby teeth and 50–59 per cent less tooth decay in adult teeth. Another compilation of studies conducted between 1976 and 1987 showed reductions in tooth decay of between 15 and 60 per cent, with the highest benefit for baby teeth, but also significant benefits for permanent teeth. Yet another systematic review of the literature analysed 214 studies to determine whether fluoride in drinking water was effective. This systematic review found that when you combine all 214 of those studies, you discover that children who got fluoride in their drinking water had fewer teeth with cavities, and were more likely to have no cavities at all, compared to the children who did not have fluoride in their drinking water. The 350 peer-reviewed references compiled by the American Dental Association in their publication Fluoride Facts also support how well fluoride works.
Of course, preventing cavities might not be worth endangering your health in other ways. Some people are concerned about water fluoridation leading to cancer, thyroid problems, neurological problems and heart disease, and other toxicities. Is fluoride really safe? Once again, the scientific evidence overwhelmingly supports the safety of adding fluoride to a community water supply. Reviews of the safety of fluoride by the Institute of Medicine’s Food and Nutrition Board, the National Research Council, the Department of Health and Human Services and the Public Health Service in the United States, the British National Health Service and the World Health Organization have all led to the conclusion that fluoride supplementation is safe, effective and recommended for community water supplies. A systematic review published in the British Medical Journal in 2000 analysed 214 studies on fluoridation and found no evidence of potential adverse effects except for dental fluorosis (which we’ll talk about in a moment). Periodic reviews every six years by the US Environmental Protection Agency continue to find no harmful effects related to fluoride in drinking water. Good scientific studies demonstrate that drinking fluoridated drinking water does not increase the risk of hip fractures. More than fifty extremely large studies do not show any association between fluoridation and the risk of cancer. One small study from the 1950s of fifteen patients with an overly active thyroid (hyperthyroidism) tried to use large amounts of fluoride as a treatment for hyperthyroidism and found that it seemed to help some patients. On that basis, concerns have been raised about whether fluoride in drinking water adversely affects the thyroid gland. Again, much better science says that the answer is no. Studies of people with drinking water with naturally high levels of fluoride found that it had no effect on the size or function of their thyroid gland, and this matches results from animal studies. Furthermore, two studies have found no association between the level of fluoride in water and thyroid cancer.
The National Research Council of the US National Academy of Sciences supports the conclusion that drinking optimally fluoridated water is not a genetic hazard. There is no known association between drinking fluoridated water and Down’s Syndrome. One psychiatrist in the 1950s published two studies claiming that the two were connected, but four subsequent studies have found no connection and experienced researchers have noted significant problems with how that psychiatrist analysed his data. There is also no generally accepted scientific evidence establishing a link between fluoridated water and other neurological disorders, including attention-deficit disorder.
One study, in which rats were administered fluoride at 125 times the level in community fluoridated water, concluded that the rats showed some behavioural changes. However, this study did not use any sort of control group to compare the rats that had the fluoride to rats that did not, and scientists who reviewed the results of this study have concluded that it is significantly flawed and cannot be used to draw conclusions about problems with fluoridated water. Moreover, a seven-year-long study in human children from birth to age six found no effects from the fluoridated water on the children’s health or behaviour, using both mothers’ ratings and teachers’ ratings of the children’s behaviour.
There is one real problem that can result from too much fluoride – dental fluorosis. This is a discolouration of the teeth that can occur when a child ingests more fluoride than is recommended. With mild dental fluorosis, the teeth get white flecks or spots, but with severe fluorosis the teeth can get a permanent brown stain. About 10 per cent of the mild fluorosis seen in children does probably come from the fluoridation of water (although the dentists argue that these small white flecks are a small price to pay for avoiding cavities, tooth decay, missed school and so on). The biggest problem with fluorosis is that kids do sometimes have a habit of swallowing their toothpaste. Fluorosis is the reason that the American Dental Association recommends that children under six do not use more than a pea-sized amount of toothpaste. We assume that little kids are going to swallow their toothpaste, and if they swallow a lot more than the pea-sized amount, they are more likely to get fluorosis. Toothpaste delivers a much more concentrated amount of fluoride than the drinking water does. The biggest cause of fluorosis is most likely swallowed toothpaste, not the water.
Many experts have concluded that fluoride is both beneficial and safe in the drinking water of our communities, and they agree that the risk of fluorosis is far outweighed by the benefits of preventing tooth decay. The American Dental Association, the US Centers for Disease Control and Prevention, the American Medical Association and the National Health Service have all issued statements supporting how well adding fluoride to water works to prevent tooth decay. In fact, the Centers for Disease Control and Prevention declared fluoridation of public drinking water to be one of the ten biggest public health achievements of the twentieth century. We agree. Grand Rapids had the right idea!