Monday, November 07, 2011

To fluoridate or not to fluoridate, that is the question. Next Tuesday at my Water District Board meeting

I'll reproduce below most of an old post about fluoridation. I had previously expected to see an identical situation with climate change in terms of the debate, but it's not. I think factors overall favor fluoridating, but not quite as overwhelmingly as I expected. On Tuesday, my fellow Directors and I get to figure out next steps.

Fluoridation opponents have made lots of mistakes in my opinion, but supporters have overstated the consensus. In particular, fluoride levels four to eight times the recommended level do have rare adverse effects, which isn't a huge safety margin in toxicity issues (UPDATE: I mean rare and severe effects - some cosmetic problems to teeth are common). Very slight adverse effects on larger groups would also be hard to rule out.

The Center for Disease Control recommends mixing non-fluoridated water in formula for babies that use formula exclusively. I can also attest to hearing from the significant number of people, if still a minority, who are just anguished that we're putting something they consider toxic in their water. Home-based reverse osmosis systems can remove their fluoride, I think.

And then there's the money cost - over $4m to construct and $800k to operate. We might get funding to construct but get stuck with operating, which people forget is the bigger cost.

So. The staff recommendation is to proceed if someone else pays for it. We'll see. If we do go forward, we may need to educate people about infant formula and let people know they can get reverse osmosis kits if they want.

Anyway, here's most of the old post, with the science:

Fluoridating water, or a funny thing happened on my way to backseat driving

I originally labelled this blog Backseat Driving back in 2004 because I anticipated it to be a blog where I would second-guess decisions made by politicians and other people. That worked out fine more or less until November 2010, when for some reason I was elected to the Santa Clara Valley Water District Board. Turns out that San Jose is the largest city in the US without fluoridated water supplies (in much of the city, anyway), and the seven of us directors have to decide whether we'll help or hinder the fluoridation process. So I'm pushed into the front seat for this one.

We've got some legal and economic issues to handle (it's not quite as cheap as everyone says, I want to know where the money's going to come from), but the relevant issue here is science. I read the guest post at climate blogger Coby Beck's place, The Case Against Fluoride, fairly closely a while back, especially the raucous debate in the comments. As a spectator with some, limited reading of the available information, I'd say the fluoridators seemed more persuasive than skeptics, but it wasn't the absolute demolishing that I expected.

The fluoride skeptics really hurt their cause when say fluoride doesn't prevent cavities - it's so obviously effective that people making this claim are damaging their own credibility. I'd consider it comparable to denying that the planet has warmed in the last 50 years.

The closer issue is adverse effects, and whether a substantial number of people are very slightly harmed by fluoridation, or if a small number of people are substantially harmed. The 2006 National of Sciences report doesn't condemn fluoridation, but it doesn't absolve it, either:
Bone Fractures

....Overall, there was consensus among the committee that there is scientific evidence that under certain conditions fluoride can weaken bone and increase the risk of fractures. The majority of the committee concluded that lifetime exposure to fluoride at drinking-water concentrations of 4 mg/L or higher is likely to increase fracture rates in the population, compared with exposure to 1 mg/L, particularly in some demographic subgroups that are prone to accumulate fluoride into their bones (e.g., people with renal disease)....There were few studies to assess fracture risk in populations exposed to fluoride at 2 mg/L in drinking water. The best available study, from Finland, suggested an increased rate of hip fracture in populations exposed to fluoride at concentrations above 1.5 mg/L. However, this study alone is not sufficient to judge fracture risk for people exposed to fluoride at 2 mg/L. Thus, no conclusions could be drawn about fracture risk or safety at 2 mg/L....

(In California, 2 mg/L was the limit, and 0.7 is the new proposed goal. -Ed)
Neurotoxicity and Neurobehavioral Effects

Animal and human studies of fluoride have been published reporting adverse cognitive and behavioral effects. A few epidemiologic studies of Chinese populations have reported IQ deficits in children exposed to fluoride at 2.5 to 4 mg/L in drinking water. Although the studies lacked sufficient detail for the committee to fully assess their quality and relevance to U.S. populations, the consistency of the results appears significant enough to warrant additional research on the effects of fluoride on intelligence....

Endocrine Effects

The chief endocrine effects of fluoride exposures in experimental animals and in humans include decreased thyroid function, increased calcitonin activity, increased parathyroid hormone activity, secondary hyperparathyroidism, impaired glucose tolerance, and possible effects on timing of sexual maturity. Some of these effects are associated with fluoride intake that is achievable at fluoride concentrations in drinking water of 4 mg/L or less, especially for young children or for individuals with high water intake. Many of the effects could be considered subclinical effects, meaning that they are not adverse health effects. However, recent work on borderline hormonal imbalances and endocrine-disrupting chemicals indicated that adverse health effects, or increased risks for developing adverse effects, might be associated with seemingly mild imbalances or perturbations in hormone concentrations. Further research is needed to explore these possibilities....
(Removed discussion of bone cancer as not very troubling given its rarity. Ed.)

These were the most troubling findings, mostly about what hasn't been proven, and mostly dealing with levels that are five times what's planned for drinking water. The report expressly ignored the benefits of fluoridation. It's important to balance out potential concerns over rare, severe complications related to fluoride with the certainty that rare, severe complications can result from cavities.

The bottom line as a policy maker in my little arena is that I shouldn't try and figure out the science myself, but I should try to figure out what the scientific consensus is, figure out where the consensus doesn't yet exist, and then plug that information into everything else we have to balance.

The science seems to favor fluoridation, but it's not a slam dunk. And we still have potential policy barriers, and the overall cost issues. Figuring this all out will be interesting.