Truthiness with Numbers

By George Johnson | February 22, 2013 12:39 pm

Yesterday on Collide-a-scape, Keith Kloor, writing about climate change deniers and opponents of genetically modified food, used a nice turn of phrase: “veneer of science.” Positions that are rooted in politics or gut-level emotions are dressed up by citing and often distorting isolated studies, ignoring that in science what counts is the body of research, the preponderance of evidence.

That perfectly describes what is happening with the fluoride debate. There is nothing crazy about thinking that high levels of fluoride can be harmful. Fluorosis of the teeth is the one risk that has been established. For excessive exposure over the course of many years, there is disputed evidence of the possibility of a weakening of bones in adults. Any other effects are even more controversial and fall into the netherworld of epidemiological correlations that may be nothing more than statistical flukes. They become a worry when naturally occurring fluoride exceeds the EPA standard of 4 parts per million, a rarity in the United States. When that happens, regulators call for fluoride to be filtered from the water. A study published in 2006 by the National Academy of Sciences recommended a more conservative limit of no more than 2 parts per million. Judging by the numbers in the report, far less than 1 percent of the population is exposed to that much.

Again, as Paracelsus put it, the dose makes the poison. But the anti-fluoride activists blur over the distinction. They use the academy’s study to argue against the recommended (not mandated) practice of reducing tooth decay by bringing water with barely measurable amounts of fluoride up to a threshold — judged harmless by the preponderance of evidence — of 0.7 parts per million.

More recently the extremists have embraced a study published last year about the possibility of neurological effects from chronically high fluoride contamination. Developmental Fluoride Neurotoxicity, a collaboration of the Harvard School of Public Health and China Medical University, looked at 25 epidemiological studies from China and two from Iran. The smallest involved 20 subjects, the largest just over 300.

“Each of the articles reviewed,” the authors observed, “had deficiencies, in some cases rather serious ones, that limit the conclusions that can be drawn.” They noted that “the studies were generally of insufficient quality.” They were done by various researchers between 1989 and 2011 “according to the standards of science at the time.”

In each study — involving communities with seriously tainted water or where people burned coal, high in fluoride, inside their homes — there were indications that the children had IQs a few points lower than for the control groups. Confounding factors, like the possibility of lead and other contaminants, were not considered.

Seven different methods had been used to measure I.Q. — the Wechsler Intelligence Scale, Chinese Standardized Raven Test, Chinese Binet Test, Japan test . . . and another just called “Child mental work capacity.” Fluoride was also measured in various ways: milligrams per liter (of water or excreted urine), milligrams per kilogram of coal, percentage of children with dental fluorosis. Three studies didn’t give measurements, only distinguishing between high and low fluoride areas.

Taking the uncertainties and imperfections into account, the epidemiologists combined the data in a meta-analysis and concluded, with all the appropriate qualifications, that “the results support the possibility of an adverse effect of high fluoride exposure on children’s neurodevelopment.” (I’m adding the italics since this distinction is so stubbornly overlooked.) They called for further research.

Inquiring reporters received the following caveat:

“These results do not allow us to make any judgment regarding possible levels of risk at levels of exposure typical for water fluoridation in the U.S. On the other hand, neither can it be concluded that no risk is present.”

Which is the problem with all of these issues: you can never prove a negative. And that opens the door for truthiness with numbers. Scienciness.


This is part 3 of three posts:

Fluoride Paranoia and Betteridge’s Law

Fluoride Paranoia, Part 2

Truthiness with Numbers

  • Buddy199

    Yesterday on Collide-a-scape, Keith Kloor, writing about climate change deniers and opponents of genetically modified food, used a nice turn of phrase: “veneer of science.”
    “Denier” is a loaded term, it’s one step above “heretic”. Skeptic is more accurate. And there’s a lot to be skeptical about. The preponderance of evidence seems to indicate that global temperatures have increased in general during the past 150 years. However, not in lock step with atmospheric CO2 levels as AGW dominant models predicted (for instance, the 1940’s drop in temperature and “flat-lining” since 1998). The preponderance of evidence also indicates that extreme weather events of late cannot be causally linked to global warming despite how “sciency” it seems. There are some pretty large questions still to be fleshed out until the science is truly settled beyond doubt.

    • Dwayne J. Stephenson

      This is exactly the sort of thing George is talking about. I’ll merely address the “flatlining claim: it’s just false.

      As a person you are entitled to your own opinions about things. You can believe that God makes all the weather happen exactly how he wants it, and that there’s nothing humans can do about it. In some ways, that would be more honest than pretending that you are in a position to out-science the climate scientists with your glorious doubt.

      • Buddy199

        Science evolves because of doubt. Religon remains static because of lack of doubt. Climate science is distorted by people who cling to it as their quasi-religon.

        • Dwayne J. Stephenson

          That doesn’t even make sense. Skepticism can be useful for brushing away bad ideas, but it’s not some unmitigated virtue. Scientists are trying to figure out how things are, and that necessarily involves committing to a large number of statements about how the world actually is. It’s true that scientific knowledge, at least in principle, is understood provisionally, and that means in practice that those statements may be subject to revision upon further experimentation or analysis. But that’s not the same as Cartesian doubt, which is scientifically useless.

          I’m willing to concede the possibility that climate scientists are wrong, just like anybody could be wrong. But what I’m not willing to do is pretend I’m in a better position than they are to understand what the hell is going on. Arguments that reduce to the form “I’m not a climate scientist, but climate scientists believe certain things that I don’t believe, and my not believing in them proves I’m more scientifically minded than them” don’t pass the smell test. At the very least, it takes a lot more work than that to give the sheen of knowledge to your ignorance.

  • Slardy Bardfast

    I am shocked at what I see in the DISCOVERY magazine these days. Here is a perfect example of what I mean:The Polluted Keystone Pipeline Discourse. The starting point for the discourse is that the Keystone Pipeline is the cause pollution. It is not. The Oil Sands of
    Canada will be harvested whether of not we allow Keystone to be built. Unless we allow the pipeline to bring that oil into the US where it will benefit the American consumer, Canada will build a pipeline to the West coast and ship the oil to China.

    Consider these facts. We get our oil from Canada at ~$60 per barrel: ~ $40 under market price. So the net effect of stopping the Keystone Pipeline: lost jobs, lost tax monies, higher oil costs for US consumers (which the environmentalist surely cheer), and the loss of a safe,
    dependable oil supply that does not put money into the hands of middle-East sheiks.

    What a shame.

  • dogktor

    Actually for Keith it IS a veneer.

    I posted links to actual science on immuno reactivity of cry proteins
    , and also pointed out that it is contradictory to pretend to advocate for global warming solutions and for adoption of GMO based agriculture, which is dependent on fossil fuels.

    Go look for my post— it does not exist.

    I now think Discover is no better than a front group/ think tank/ PR group

    –there is nothing scientific about it.

    • Keith Kloor

      I have not deleted any of your comments, much less moderated them. They have appeared just as you wrote them. I do not engage in censorship of differing viewpoints. On the contrary, I encourage them.

      Perhaps the one comment you are referring to is stuck in the spam folder due to multiple links. I will see if I can find it.

    • underdabridge

      dogkor, you sound exactly like the science as a veneer types this post is about. Is that why you need to complain about something, so you are the victim again?

  • dm11001

    Do you ever worry about the emphasis on consensus when communicating with the public about the science of an issue? I understand the reluctance to engage in dueling studies (“you have a study that shows a correlation between historic CO2 levels and planet temperature? Well I have a study that shows the CO2 levels lag temperature increases!”) However, are we not badly miss communicating how science gets done? Are we, as usual, underestimating the intelligence of the public. I would argue that the emphasis on consensus leaves policy advocates vulnerable. If we discover that the consensus of the last 40 years regarding the role of fat/saturated in heart disease and obesity was way off we will have to admit that the process of turning science into policy is broken. I will admit it’s a hypothetical but the parallels between the “lipid hypothesis”, global warming, and drinking water flouridation are interesting. I can elaborate on that last point if you like.

    • byGeorgeJohnson

      You make a good point. I think it is important to not just explain the consensus but to give readers a sense of how it emerged. Of course that can’t be done in every story. Ideally the day to day coverage of an issue will be interspersed with pieces that step back and neatly explain the science — not just the certainties but the ambiguities. That was easier to do when people came to the same publication time after time to follow a story. With the Internet the context is so often lost.


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Fire in the Mind

Whether a subtle new pattern shows up in an experiment on the Higgs boson, an epidemiological report about a suspected cancer cluster, or a double-blind trial purporting to demonstrate ESP, it can be maddeningly difficult to distinguish between what we see and what we think we see. "Fire in the Mind" takes a look at the big questions behind today’s science news.

About George Johnson

George Johnson writes about science for the New York Times, National Geographic Magazine, Slate, and other publications. His nine books include The Cancer Chronicles: Unlocking Medicine's Deepest Mystery (August 2013), The Ten Most Beautiful Experiments, A Shortcut Through Time, and Fire in the Mind. He is a winner of the AAAS Science Journalism Award and has twice been a finalist for the Royal Society science book prize. Co-founder and director of the Santa Fe Science Writing Workshop, he can be found on the Web at Twitter @byGeorgeJohnson.


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