Most Manitobans, two in five Saskatchewanians, almost one in two Albertans, but fewer than one in ten British Columbians, live in communities with fluoridated water. Some people are concerned about this practice. Many communities have been considering whether to continue with it. They look to experts, community members, and scientific literature to help make the decision. In some places, residents have been asked to vote or give their views. To make an informed decision about this practice, water fluoridation and the issues around it must be fully explored.
Fluoride is a natural element found in varying amounts in air, earth, and all water. It is also found in food and drink made from water containing fluoride. Fluoride and products containing fluoride are used in industry and health care. Many personal dental care products such as toothpastes and mouth rinses contain high levels of fluoride.
Water fluoridation is the controlled addition of fluoride to public water systems that have naturally low levels of fluoride. The goal is to bring the fluoride to a level where it can help reduce dental caries. In Canada, the current standard for fluoride in water systems is 0.8 parts per million (ppm) or 0.8 milligrams per litre of water.
At these levels, fluoride and accompanying compounds found in products added to our water do not exceed currently accepted guidelines for public water systems. Local municipalities or water commissions control the addition. As with any substance added to the water supply, it undergoes quality assurance to control levels in the water.
The annual cost per person can average between fifty cents in large communities to three dollars in smaller ones. In most cities, every dollar spent on fluoridation can save on average as much as $38 in dental treatment for those drinking the water. Fluoridation has the potential to greatly reduce dental disease for much less than it takes to treat it.
Water fluoridation has been used in North America for over sixty years. During this time, significant research has considered its effectiveness and safety.
Thousands of scientific articles that address fluoride in some way have been written in the past decade alone. Varying types and qualities of research exist on both the pro- and anti- fluoridation sides. In particular, the Internet is an easy way for people to read and share information on this topic. Although an article may have been published, the scientific methodology it refers to is not always strong.
The challenge in making the best choice involves sifting through a huge amount of material. When most people research a topic like water fluoridation, they actually see only a very small portion of the vast amount of information available. Some of it can be biased and of questionable quality. Making a good decision about such a complex issue involves reviewing all of the available information and choosing the best evidence.
Decisions about health should be based on the strongest evidence you can find. Otherwise, you could make a choice that harms your health or puts you at risk of disease.
Pay attention to both the amount and quality of the evidence presented. Reading one or even dozens of articles cannot answer the complex questions involved in such an issue. This is especially true for self-published opinion pieces. Articles that have been evaluated (peer-reviewed) by experts in the field are usually of higher quality. Even then, the information needs careful review before it is accepted.
This type of research is one of the strongest tools available for complex questions like water fluoridation. Systematic review is especially useful for reviewing scientific literature that is extensive and at times divided on a given issue. Investigators that complete a systematic review do not just look at a few of the articles on a topic. Rather, they scan the entire scope of the literature. They remove articles that do not exactly address the question being asked, as these potentially bias the findings. Articles with weak evidence are also removed. The remaining body of research is of high quality, with the least bias and error.
Most people do not have the time or specialized knowledge that systematic review requires. Our best bet is to look for information that has been given this careful, critical, and systematic scrutiny by peer-review investigators.
Acids made by bacteria decay tooth enamel. Fluoride reduces dental caries by helping teeth regain minerals after there has been some erosion of the enamel. The best way to deliver fluoride is through constant or regular low doses in the mouth. Water fluoridation and other fluorides like toothpaste and mouth rinses do this. This benefits not only children, but anyone who has teeth and so is at risk of dental disease.
Over the past decade, a number of systemic reviews have examined all of the scientific literature on water fluoridation, both published and unpublished. After selecting the best evidence, water fluoridation was found to be effective in reducing dental caries. An expert panel called together by Health Canada in 2007 stated, "Community drinking water fluoridation is still an effective public health method to reduce the prevalence of dental caries in the Canadian population."
This effective tool is available to all Canadians with access to publicly fluoridated water, not just people who purchase or use other fluorides like toothpaste.
Some fluoride found in water, foods, and dental products is swallowed and taken into the body. (This is called systemic application.) Other fluorides are applied to the teeth, but are spit out. Most of it is not swallowed. (This is called topical application.) Like many other substances we ingest, fluoride can do harm if too much is taken in.
The levels of fluoride in fluoridated water are well below those that might be harmful. One key possible side effect involves slightly higher levels of fluoride being swallowed over time while the teeth are developing. Called enamel or dental fluorosis, this generally shows as fine, white lines or spots on the teeth. It is usually hardly noticeable. In those few children swallowing very high levels of fluoride (well above 1.5 to 2.0 ppm), fluorosis can cover much of the teeth. At those levels it may also be brown in color and cause small pits in the enamel.
Recently, the Canadian Health Measures Survey (2007) looked at dental health across Canada. Only one in six children in Canada were found to have mild or very mild fluorosis. There were very few with moderate to severe fluorosis.
When weighing possible harm from fluoride, the risk of cancer, bone fracture, mental illness, goiter and other health concerns were considered. Systematic reviews found the amount taken in through water fluoridation poses no significant risk to health. As with other health measures, research continues. Water fluoridation is still being monitored to ensure safety.
Traditionally, decisions regarding health are approached using a biomedical ethics model. Following this model, health professionals must provide all of the information people need to make independent choices about their health. However, this is very difficult to do with large public health strategies designed to improve both the environment and the health of those living in it. Instead, communities must be consulted as part of the decision-making process.
In Western Canada, local municipal councils usually make decisions about water fluoridation. Often, the public voices opinion in a plebiscite or public forum.
Still, many attempts at public input on fluoridation have not allowed all residents to voice their opinion equally. It is critical for those making decisions to understand the will of the people through properly developed polls or plebiscites. They should also consult experts who fully understand how to evaluate scientific literature. This is an important part of ensuring that decisions affecting public health are not made based on biased opinion or political whim.
The issue of water fluoridation is complex. It cannot be easily addressed in public forums or debates in the media, which are often dominated by emotion and bias on both sides and are not of sufficient scope to truly evaluate the scientific evidence. These exchanges may stimulate a desire to know more about the issue. However, knowing the will of the community and careful evaluation of all available evidence by decision-makers is required to make a truly informed decision on behalf of the public. This attention to detail makes certain that valuable services that maintain health will not be removed, while ensuring that these same services are effective and safe. To date, careful reviews of the scientific literature continue to support the effectiveness and safety of water fluoridation. Close examination and research is required to ensure that, in our ever-changing environment, we can maintain this standard.
British Columbia: www.healthlink-bc.ca/healthfiles/hfile28.stm
(on the left hand sidebar, select 'Environmental Health' and then 'Dental/Oral Health'