Thursday, January 29, 2009

A Plea for Equal Opportunity Cynicism

Another health-related scare is stirring things up in the momosphere. This time, it is trace amounts of mercury in high-frutose corn syrup (HFCS). Note I said "trace amounts". Most of the media reports on this did not, although the levels found really are small.

I posted my opinions on this latest scare on the threads on Mom-101 and Ask Moxie. In short, the study that got everyone all excited, which tested name brand products, reported mercury level in the parts per trillion range. One of the highest levels report was 350 parts per trillion in Quaker Oatmeal on the Go. The FDA reports mercury levels in fish in parts per million, and the EPA regulates mercury levels in drinking water in parts per billion. I took the EPA's reference dose for mercury, set with the safety of pregnant women in mind and considered by some to be among the most stringent standards in the world and calculated how many Oatmeal on the Go bars a 150 lb woman would have to eat to be worried. I came up with 30 bars. That is 30 bars in one day.

Now, I'm not saying that we shouldn't try to get the mercury out of HFCS. However, the data in this study in no way supported the level of concern expressed in the study sponsor's press release, which was then dutifully repeated by the mainstream press.

I have very little patience for this sort of study. It wraps itself in the cloak of "science", but isn't really science at all. The results were not peer-reviewed. The conclusions were not supported by the data. This study uses scientific tools, but is not science. I suspect the institute that released it (the Institute for Agriculture and Trade Policy) has an agenda and that the agenda is not to provide American consumers with accurate information about food safety. I think it is wrong to use questionable science to try to induce fear in parents so that they will support that agenda. Do you want me to support the elimination of HFCS from out food chain? Fine. Convince me on the actual merits of that. Don't set up a false bogeyman of mercury poisoning to try to trick me into supporting your goals.

The other thing that bothers me about this sort of story is how quickly people dismiss the FDA and EPA as biased by lobbying from big corporations, but how easily they accept the conclusions of a report from an institute I suspect they had never heard of before. I have written before about this distrust of the government science agencies, and I put the blame partially on the Bush administration's willingness to pick and choose science that suited its policy needs. Now, I'm seeing the same selective science on the political left, too. It is fine to be cynical and demand to see the government's proof that some food additive (or what not) is safe. But you also need to be cynical and demand proof from those people who are claiming it is not safe. If you are not equal opportunity in your cynicism, you are not using science to help you determine your policy opinions. You are letting your policy opinions determine what science you accept. And that is wrong, whether you are George Bush or Greenpeace.

I realize that not everyone has the training in science to critically evaluate all the evidence. This is why I argued that we should let the experts do this work for us. However, if you don't trust the FDA and EPA to do that, you can still evaluate the claims that you read in news reports and on other people's blogs. Here are the steps I follow:

1. Check the source.
Go straight to the original study being cited. First, check that the conclusions the authors state actually match what the news report or blog says. Next, look at the study. It is a bad sign if it has a cover with splashy graphics on it- true scientific studies don't usually have this. Is it published in a peer-reviewed journal? If not, the study has not been reviewed by other scientists, and is less reliable.

Finally, look at who did the study. I usually check to see if it is some place I've heard of. Obviously, if you don't work in biomedical science, this will be a less relevant check. However, studies from academic institutions and institutes whose mission is biomedical research are usually pretty good sources. "Policy institutes" and watchdog groups usually have an agenda, which may or may not include the publication of fair and unbiased studies on the subject at hand. Read what their website says their goals are and think critically.

2. Compare the measurements with those in other scientific literature.
It is troubling if the study is reporting measurements orders of magnitude below the levels other studies say are of concern. Often, a simple Google search will turn up the relevant FDA, EPA, or CDC webpages with the government regulations on the subject. If you don't trust those sources (and in most cases, you should), you can also search the scientific literature directly using PubMed. You will usually be able to read the abstracts of the papers you find. Scientific abstracts aren't like the teasers on the backs of books- they will almost always include the conclusions of the study.

3. Read the conclusions of the report critically
Remember that correlation does not equal causation- i.e., data showing that two things are correlated can not be used as the sole proof that one of the things causes the other.

I know this sounds like a lot of work- it is. Which is why I usually let the experts do it for me.


  1. I read that there were "detectable amounts" of mercury in HFCS. But there is a difference between detectable levels and harmful levels. I wasn't alarmed at all. But, then, I am a scientist.

    There are lots of good reasons to avoid HFCS, besides mercury.

  2. I was so glad you commented on Ask Moxie. I didn't realize how small the amounts were, because you are right in that the report didn't say or compare.

    I'm the type of person who doesn't believe anything until I triagulate with credible sources (I would say it's my journalism background, but I was like this before I studies journalism). Unfortunately (maybe fortunately), I'm also a huge conspiracy theorist type of person in many things, but my distrust is an equal opportunity distrust until I have corroborating evidence from respectable sources. But this means I distrust the government as much as some watchdog group.

    I don't like HFCS for multiple other reasons. I've researched HFCS and am comfortable with my decision to cut way back it. But not because of the mercury. Still, no mercury would be better than even detectable amounts.

  3. @caramama- Scientists tend to be pretty cynical, too. I don't know if that is due to the training or if it is a personality trait that tends to push people towards science. Probably both.

    And any scientist who can't take someone trying to poke holes in his/her data and conclusions got off too easy in grad school.

    I haven't done the research on HFCS and don't really have an opinion on that yet. I don't really drink soda and I usually try to make my own cookies and similar treats (this slows down my consumption), so I don't think I actually eat much of it. So I haven't worried about it.

    My personal food safety issue on which I disagree with the regulatory agencies is our (over)use of antibiotics in livestock. This is pretty much the reason I buy organic milk and meat.

  4. Anonymous10:37 AM

    ...but how and why is there any mercury at all in HFCS?

  5. @anonymous- I'm not an expert in this area, but I think the two likely routes are (1) contamination left from the processes used to extract the sugar from corn, and (2) contamination in the corn itself, probably from mercury pollution in the environment. I do not think mercury is used in the extraction of sugar from sugar cane or sugar beets- but I do not known that for sure. However, cane and beets would be susceptible to exposure from environmental pollution, too. I do not know what the relative uptake of mercury of corn, cane, and beets is, though.

    I've never seen anything to make me think the amounts of mercury found in any food stuff except predator fish is sufficient to concern anyone- but again, this is not my area of expertise.


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