Dot Earth Blog: Single-Study Syndrome and the G.M.O. Food Fight

[This is a modified, expanded version of my Tumblr post from yesterday. I was on the run between Arctic ice symposium and teaching duties; more on ice anon.]

11:31 a.m. | Updated below as marked |
I?ve written here before about what I call ?single-study syndrome,? the habit of the more aggressive camps of advocates surrounding hot issues (e.g., climate, chemical exposure, fracking) to latch onto and push studies supporting an agenda, no matter how tenuous ? or dubious ? the research might be.

Here?s a fresh example from the food wars, which are particularly heated right now because of California?s looming vote over Proposition 37, which would require labeling of genetically modified foods:

Groups opposed to genetically modified crops or ?Big Ag??are heavily promoting a?new study?claiming to find big impacts on longevity and cancer rates in rats fed Roundup-ready corn (and separately exposed to the herbicide for which the corn variety is named). Andrew Pollack?s?news article on the study?describes the methods and findings.

The study has been?quickly and widely criticized, even as it has been written on far and wide.?One issue is that, while the experiments ran for two years, far longer than most rat studies of food safety, the chosen rat breed commonly develops tumors after two years. Combined with small sample size (the different test groups had 20 animals each), this has led even some advocates for G.M.O. labeling to question the results.

The food researcher and writer?Marion Nestle, a supporter of labeling, called the study ?weirdly complicated? in?an excellent look at the work?posted yesterday by Tim Carman of the Washington Post.

In Rosie Mestel?s?Los Angeles Times article, another scientist said the combination of a tumor-prone rat breed and small sample size created big problems:

Another red flag was that tumor rates didn?t increase in line with the dose of GMOs fed to animals, as scientists would expect to see if the genetically engineered corn were to blame, said Kevin Folta, a plant molecular biologist at the?University of Florida?in?Gainesville. Instead, ?you are likely seeing variation of normal tumor incidence in a small population of rats,? he said.

Please read the pieces by Carman and Mestel end to end if you have time.

For more background on the California ballot tussle, read Stephanie Strom?s recent feature and video report.?Here?s my view. As I wrote in considering ?pink slime:?

I?m all for?open disclosure of food contents, but not when the labeling effort is aimed at fomenting fear over facts. (This issue goes far beyond beef byproducts; I encourage you to read this Colorado State University analysis ofthe issues surrounding labeling of genetically engineered foods.)

While I?m for transparency, I don?t like the California initiative because it?s rife with exemptions and special cases, all of which speak of a double standard and point to the intent being less to protect public health than make life complicated or costlier for some agriculture sectors.

If a fair labeling process were somehow created, I actually think it?d build public support for genetically modified foods in the long haul, primarily by illustrating how many safe, nutritious foods now unremarkably contain some constituent from this form of agricultural technology.

I?ll set up a separate post to vet the prime arguments on all sides. My colleague Mark Bittman has a different view, laid out in ?G.M.O.?s: Let?s Label ?Em.?

For more on the debate over risks from Roundup-ready corn and the herbicide Roundup, read biologist* Michael Eisen?s June blog post: ?#GMOFAQ How Bt corn and Roundup Ready soy work, and why they should not scare you.?

[11:31 a.m. | Updated | Professor Eisen, who?s at the University of California, Berkeley, sent this reaction to my post:

It?s a really messed up field. The vast majority of research on GMO safety ? on both sides ? is done by people out to prove something rather than investigate something. This affects every aspect of the work, from study design, to execution, interpretation and publicity.

This particular study was so poorly designed ? the highly sensitized line, the inexcusably small number of animals ? that you didn?t even have to look at the ridiculous statements from the lead author (like ?GMOs are a pesticide sponge?) to see that it was biased.

The result of all of this severely tainted work (and there?s plenty from the pro-GMO side too) is that the really good science in the field gets drowned out, and isn?t taken seriously because people just assume that it, too, must be biased. Total mess.

For a broader view of the literature on health studies focused on genetically modified foods, read this review paper from 2011:??Assessment of the health impact of GM plant diets in long-term?and multigenerational animal feeding trials: A literature review.?

Abstract:

The aim of this systematic review was to collect data concerning the effects of diets containing GM maize, potato, soybean, rice, or triticale on animal health. We examined 12 long-term studies (of more than 90?days, up to 2?years in duration) and 12 multigenerational studies (from 2 to 5 generations). We referenced the 90-day studies on GM feed for which long-term or multigenerational study data were available. Many parameters have been examined using biochemical analyses, histological examination of specific organs, hematology and the detection of transgenic DNA. The statistical findings and methods have been considered from each study. Results from all the 24 studies do not suggest any health hazards and, in general, there were no statistically significant differences within parameters observed. However, some small differences were observed, though these fell within the normal variation range of the considered parameter and thus had no biological or toxicological significance. If required, a 90-day feeding study performed in rodents, according to the OECD Test Guideline, is generally considered sufficient in order to evaluate the health effects of GM feed. The studies reviewed present evidence to show that GM plants are nutritionally equivalent to their non-GM counterparts and can be safely used in food and feed.

Addendum: When research cuts against an agenda, other issues arise. A ridiculous petition has been initiated aimed at forcing the retraction of a paper by Stanford University scientists on the relative nutritional merits of organic and conventional foods. Rosie Mestel, a vital guide on such issues, did a valuable piece that essentiallydismantles the assertions of the activists pushing the petition. I agree with Paul Raeburn, writing on Knight Science Journalism tracker, who?hailed the story?for charting ?a clear path for us through a nasty thicket.?

11:34 a.m. | Clarification | * Michael Eisen, while writing much on genetics, is better described as an evolutionary biologist. I originally described him as a geneticist.

Source: http://dotearth.blogs.nytimes.com/2012/09/20/the-gmo-food-fight-rats-cancer-and-single-study-syndrome/?partner=rss&emc=rss

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