Yesterday, voters in the Portland, Oregon area rejected a public health measure that's been widely adopted elsewhere in the US: water fluoridation. The treatment of drinking water with trace amounts of fluorine has a clear, positive effect in preventing tooth decay, and extensive studies (including some cases where water sources are naturally high in fluorine) have indicated that the levels used in water supplies have no adverse effects on health. But amidst talk that wouldn't seem entirely out of place in Dr. Strangelove, a measure that would have started water fluoridation failed by a 20-point margin.

The evidence in favor of fluoridation's benefits is so strong that the CDC has named it one of the greatest public health accomplishments of the past century. As a somewhat snarky Slate piece on the Oregon ballot measure notes, a huge number of medical organizations are on record as supporting it. In fact, the benefits were so clear that the Portland city council approved a plan to start adding fluorine to the city's water.

That, however, triggered enough outrage that the plan eventually ended up as a ballot measure. And the outrage lasted throughout the campaign over the ballot issue, by all accounts. Along with some civility, science itself went out the window. The campaign against fluoridation put up a website that said (contrary to evidence) that fluoridation doesn't actually work. It also plays a bit on chemophobia, calling the treatment an "industrial byproduct" and focusing on the tiny amounts of trace contaminants that come with fluorine. More generally, opponents focused on how pure the existing water supply was (without mentioning "purity of essence," though).

So for now, some of Oregon's residents will be doing without fluoridation. But the city has voted on the issue four times over the past 50 years, so it will invariably come up again.