Monday, July 30, 2012by George Johnson
It is a long, difficult process. But over the years as thousands of scientists collaborate and compete, a consensus will emerge: Life on earth evolved and changed through random variation and selection. The universe began with a big bang and is continuously expanding. The knowledge will never be complete, and sometimes an anomaly will arise — a scrap of data that doesn’t fit into the big picture. If enough of these accumulate, an area of science might undergo a paradigm shift. The sun, not the earth is the center of things. Andromeda is not a small, nearby cloud of light but a galaxy far, far away. More often the anomaly will turn out to be wrong. If not the theory will be modified. It is through this give and take that knowledge emerges.
Participants at the Aspen meeting were flabbergasted when I told them that the Santa Fe City Council, acting on the testimony of a few citizen scientists whose only qualification was an Internet connection, had decided to stop fluoridating the water supply. The vote has since been rescinded. But when the hearing on the issue comes around in August, the loudest voices will arise from those who know the least.
None of these people would consider themselves scientifically illiterate. They have filled their heads with a lot of stuff. Starting with what they already were convinced was true, they ventured into cyberspace to pick and choose the evidence that suited them. Or more likely they found an advocacy group, the Fluoride Action Network, that had already done the choosing for them. But they miss or choose to ignore the dynamic through which real science unfolds.
A study I mentioned earlier, When Public Action Undermines Public Health: A Critical Examination of Antifluoridationist Literature, describes the phenomenon:
Although the overwhelming majority of scientific enquiry supports the benefits of water fluoridation, members of the public who type the term “water fluoridation” into any of the major search engines would immediately be presented with a disproportionate percentage of anti-fluoridation websites.
The information ranges, the authors note, “from factual, to unsubstantiated opinion, to outright fraud.”
As they go about their “research,” what the citizen scientists won’t find is a single definitive study — where, let’s say, identical twins were taken from their mothers at birth and raised with and without 0.7 milligrams of fluoride in their drinking water and with all other variables — number of candy bars eaten, frequency of brushing teeth — carefully controlled and accounted for. Instead beginning in the 1940s there is one imperfect study after another. Each was conducted differently and each has its own strengths and weaknesses. That is the nature of epidemiology.
But taken together the accumulation of evidence has persuaded the American Public Health Association to strongly recommend “the fluoridation of all community water systems as a safe and effective public health measure for the prevention of tooth decay.” The group’s paper, Community Water Fluoridation in the United States, describes its reasoning and cites the supporting studies. A Systematic Review of the Efficacy and Safety of Fluoridation, a long study by the Australian Government’s National Health and Medical Research Council, reaches a similar conclusion.
Next month’s hearing will be filled with testimony from people who believe that they have found the smoking gun — some study, ignored or suppressed, that threatens to topple the scientific consensus. I’ll examine the evidence they are likely to present in a future dispatch. But the important point is that there is an expert body of opinion on water fluoridation. As they decide whether or not to overturn a longstanding public health policy, our counselors — those which are scientifically literate — will have to take that into account.