Portland made the health-related news last week by voting down a measure to add fluoride to the city’s community water supplies, with a 60% to 40% vote. This is the fourth time Portland has voted against water fluoridation since 1956, making it the most populous US city that doesn’t add fluoride to its finished water supply. Proponents of the measure quoted the CDC’s ranking of water fluoridation to prevent dental caries (cavities) as one of the top ten public health achievements of the 20th century. Opponents of the measure, who were victorious last week, expressed doubt of the true significance of dental caries prevention, concerns about health risks from excess fluoride ingestion, and simple distaste for tainting their relatively pristine water supply.
Okay, so, you’re probably thinking, “Sure, but c’mon it’s Portland – land of liberal wingnuts living off the grid – is there any real reason to take their concerns about water fluoridation seriously?” Heck, even news stories of the topic portrayed Portlanders as character sketches from the show Portlandia, represented by a diverse cast including indie rockers, mimes, stilt-walkers, flame jugglers, organic-food purveyors, craft beer brewers, and artisanal bakers.
“Some of Portland’s famed craft brewers weighed in with a risqué photo exhibit—”Brewdoir Photography”—of semi-clothed craft brewers in a fundraiser this month. Brewer Larry Crouse and a business partner posed in boxer briefs with the words “No Fluoride in My Beer” across their bare backs. “It was all very tasteful,” Mr. Crouse said.”
These news tidbits do make the Portland issue hard to take seriously as a representative concern for the rest of the country. At any rate, based on intriguing controversy, I felt the issue deserved a rethink by me – including reading the latest health research on the topic in addition to the news media.
Here are my conclusions and thoughts:
1. Public health programs to fluoridate drinking water truly have been successful in lowering cavities.
You see this in study after study – across time and different geographic regions. It shows up in studies comparing regions with naturally occurring fluoride in their drinking water to those with lower fluoride levels, in studies comparing regions with- and without fluoridation programs, and with tracking of dental caries rates within the same regions before and after inception of water fluoridation. Even further evidence is provided when dental caries rates increased in European countries that ended fluoridation programs. Sure, some observations don’t support this conclusion, such as regions that ended fluoridation programs yet saw no change in dental caries or actually saw improvements. Opponents of fluoridation of Portland’s water have pointed to results from a state-wide survey showing that their city’s dental caries rate has gone down since 2007 and is already lower than in Oregon towns with fluoridation programs in place (2012 Smile Survey, State of Oregon). But I recognize these aberrations as characteristic of observational research in human populations, among communities that differ in many ways from eachother. The average of many data points over time and different types of communities tells the underlying story.
One complicating factor is that the benefit of water fluoridation may actually be more difficult to see in recent years, since use of fluoride toothpastes have become the norm and other preventive measures like dental sealants are also common. For these reasons, the marginal public health benefit of water fluoridation may be smaller than before, and it may now only be benefiting subpopulations with less dental hygiene or preventive dentistry.
2. The unfortunate effect of dental fluorosis (chalky whitening, staining, and pitting of teeth) has increased since drinking water fluoridation programs began.
Increases in dental fluorosis have been observed in many of the same types of studies that have shown a reduction in cavities. Although this condition is not considered a serious health problem in and of itself, people with dental fluorosis do ironically have higher risk of developing cavities and they may also suffer psychosocial difficulties. The condition may point to a history of high fluoride intake during infancy when teeth are forming – a life stage that is also a critical window for other aspects of development, such as brain function.
The trouble is that the water fluoride concentration at which fluorosis occurs overlaps with the range at which the public health benefit of lower dental caries is seen. So, there is a clear risk to a minority at the allowable levels for community drinking water. This was discussed in a recent evaluation of the governmental process for weighing risks and benefits for “nutritional additives” to the food supply (Toxciology 2010), and is best seen on their graph, which shows risk of fluorosis increasing in a dose-response fashion starting at 1 mg/L, and reaching endemic levels (the “Adverse effect zone” on the graph) at 2 mg/L, within the acceptable range for US community water supplies.
3. There’s probably not enough information at this time to evaluate whether drinking water fluoridation causes other health risks, such as cancer, kidney disease, thyroid dysfunction, or cognitive problems.
Most of the studies to be found in the PubMed database are on dental caries (mostly showing benefits) and fluorosis (showing risks). There simply haven’t been many studies looking at other health endpoints from fluoride in drinking water. A few show mixed results for osteosarcoma (bone cancer), but other cancers have mostly been studied in only a crude fashion, comparing death rates rather than actual cancer diagnoses. There have been a couple of studies suggesting increases in kidney and thyroid diseases, but there hasn’t been sufficient research to either refute or confirm these findings.
The latest study to cause a stir was a meta-analysis (statistical analysis of combined data points from many studies) of IQ in relation to fluoride in community water (Environmental Health Perspectives 2012). In this analysis, Dr. Choi and colleagues combined results from 27 studies that compared regions with high fluoride levels to those with lower levels. The studies were mostly conducted in China, and most of the ‘exposed’ regions had higher fluoride levels than in US finished water supplies. Nevertheless, the results were startling in that they showed a striking decrement in IQ points associated with drinking water fluoride exposure. Even though there are several reasons why the results from this study can’t be used to evaluate the possibility of similar risks from lower-level fluoridation in US supplies, the authors urged further research on the topic, including close evaluation of dose-response relationships. Given that other metals such as lead are known to affect children’s cognitive development and have no low level at which effects aren’t seen, I would consider further research on fluoride to be needed before starting more fluoridation programs.
Proponents of fluoridation argue that the poor suffer disproportionately without water fluoridation since they have less access to preventive dentistry. However, I would think that lowered IQ from excess fluoride intake would also disproportionately affect the poor, given their socioeconomic disadvantages that limit educational opportunities. The National Association for the Advancement of Colored People (NAACP) in Portland used a similar argument against the recent ballot measure – that black communities would disproportionately suffer if fluoridation might aggravate kidney problems (again, probably unfounded at this time because there aren’t enough studies on the topic), since African American have higher rates of diabetes-related kidney problems to begin with.
4. Finally, this episode brings up some important questions about ethics of governmental public health measures.
One of the arguments put forth by Portlanders in opposition of water fluoridation is that it removes personal choice and amounts to administering medication to the public without their informed consent. This is an interesting argument since most public health interventions do allow some degree of personal choice (e.g., the addition of iodine to table salt or folic acid to breads and cereals still allows the possibility for the consumer to choose alternate products), whereas there’s no realistic substitute for use of the community water supply. Should public health programs be designed to always allow some degree of personal choice? In this situation, an alternative intervention could consist of fluoride rinses available at schools for families that choose to participate. However, this would certainly be a more costly and logistically-difficult program to implement than the simplicity of adding fluoride to drinking water.
Since the vote, Portlanders have been decried as anti-establishment, libertarian, or simply contrarian. I am not an exceptionally liberal person, although I do tend to vote Democratic. What I believe in is objective evaluation of the data on a given topic in order to weigh the risks to the benefits, with reevaluation of the issue when new data emerge. Having looked at this issue over the past week, I do see broad gaps in the literature that would give me pause if I were voting on the measure. I’m not suggesting to halt fluoridation programs that are already in place, but instead to start a reexamination of the issue, with well-conducted research on possible health effects including cognitive development, and with evaluation of true fluoride doses from multiple sources (including water, toothpaste, rinses). My generation has certainly benefited from lower rates of cavities from fluoridation of drinking water. At the end of the day, however, I’m glad we live in a country where, with enough organization, the people can still have a say about implementation of these types of public health programs.
by Anneclaire De Roos