When I was a young boy fluoridation of municipal drinking water was a no brainer except for the unstable fringe who thought it was a communist conspiracy to poison America. Fluoridation was viewed as a relatively inexpensive and safe way to give young people (especially those with less access to regular dental care) increased resistance to caries. But some communities, such as in Oregon, are resisting fluoridation proponents (Oregon ranks third from the bottom in percentage of residents using fluoridated water supplies). Portland, which has a reputation for good quality drinking water, does not add fluoride to its municipal water supply. There is a bill under consideration in the state legislature to require fluoridated drinking water and its not moving quickly. The bill was reported out of committee to the floor without a recommendation, a sign that there is not a solid majority behind its adoption. Some recent science is providing fluoride's detractors with reasons.
The three main chemicals used in the US to put fluoride in drinking water are waste byproducts of the phosphate fertilizer industry according to the US Centers for Disease Control. This fact is also recognized by the National Research Counsel. The problem is that as waste byproducts the fluoridation chemicals are not pharmaceutical grade. They contain heavy metals like arsenic, lead, and mercury which bio-accumulate and are toxic at minute levels. Fluoridation advocates do not dispute this, but argue that the concentrations are too low to present a health threat. But in the 135 Oregon communities that have already exceeded drinking water standards for toxins like arsenic, it does not make a lot of sense to those citizens to add more.
The rationale for fluoride gets weaker when you consider the evidence that swallowing fluoride does little to prevent tooth decay. What is proven effective is the topical application of fluoride to tooth enamel, such as using a fluoride toothpaste regularly. Statistical data from the CDC and the US Department of Health Services--both organizations continue to recommend fluoridation as effective--show that increasing the percentage of a state that is "fluoridated" does not correlate with fewer cavities in children. For example, in Washington state 58% of the people drink fluoridated water but it has a significantly lower percentage of poor children with good teeth than Oregon (7.1% less) where only 19% of its residents drink fluoridated water. What correlates strongly with healthy teeth in children is recent access to preventive dental care. Oregon does not do so well in this category. It has the dubious distinction of having the second lowest percentage of children in the US who had access to dental care within the previous year. A 2006 Harvard study funded by the US National Institute of Health found that drinking water fluoridation at an optimum level increased the risk of bone cancer in young boys (6-8 years old) by over 500%.