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Thursday, December 15, 2011

24 Long-Term Feeding Studies Reviewed By European Scientists Support GMO Safety

An argument frequently made by the opponents of plant genetic engineering is that there have been no long-term, independent studies about the safety of GMO (genetically modified organisms) crops.  Actually, there has been quite a lot of research on that question and it supports the safety of the technology.  A major new review on the question of long-term feeding effects of GMO crops is about to be published.  It was written by a group of seven European scientists from the public sector, and will appear in the Journal: Food and Chemical Toxicology.   The authors examined a large body of peer reviewed, scientific studies on the topic and identified 12 long-term feeding studies (longer than the typical 90 days and up to two years) and 12 multigenerational studies (2 to 5 generations).  They reviewed all of these papers in detail and came to the following conclusion:

"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."

OK, this is "science-speak" for "we really didn't find anything to be concerned about."

Reasons To Take This Paper Seriously

  • The authors are independent academic and public sector scientists
  • The studies they reviewed are all by independent, publicly funded, academic groups
  • The studies looked at many different crops (maize, rice, soybeans, triticale, potato)
  • The studies included both commercial and purely academic GMO examples (insect resistance, herbicide tolerance, pollen protein expression - a non-commercial example)
  • Many different animal models were included (rodents, cows, goats, salmon, macaques, chickens, quails, sheep)
  • The various researchers examined scores of biological parameters looking for any negative effects
  • This review has been conducted by highly qualified scientists and their paper was also peer reviewed
  • The paper addresses an important question, but in doing so it adds to many other European-based findings supporting the safety of GMO crops and foods
So even though one can never "prove a negative,"  this sort of extensive scholarship must be taken seriously. What has NOT been found means quite a bit.

The authors also provided a useful critique of these independent studies.  In many cases the GMO and non-GMO feeds were not from near isogenic lines, sometimes the event was unspecified, and in some cases the crops were grown under different conditions.  All of this can lead to differences that cannot be clearly attributed to whether the crop was GMO or not.  The downside of independent testing of this type is that potentially misleading results can emerge and cloud the discussion.

Why Does This Matter?

It matters because 16 years into the commercialization of GMO crops, controversy persists. To date, most of the commercial GMO crops are ones that are either used for animal feed or are the source of refined ingredients in human foods.  They have not, for the most part, been crops that people eat "whole." That barrier may need to be broken as one component of efforts to feed humanity over the next several decades. There are three immensely important food crops which are not now GMO on a commercial scale:  wheat, rice, and potatoes.  That may change in the next several years.

Potatoes were actually one of the very first commercial GMO crops but were unofficially sidelined by companies worried about consumer backlash. GMO potatoes may be getting a new look because scientists are working on a GMO trait for resistance to "late blight," the most serious disease and one which costs grows a great deal to control.  European farmers would benefit from such a trait even more than those in North America.
GMO wheat was blocked in North America early this century by European and Japanese wheat customers.  The wheat growers in the US, Canada, and Australia have agreed to pursue a simultaneous commercialization of GMO wheat so that they cannot be frustrated by a non-scientific barrier again.

Recently, China has begun pre-commercialization trials with an insect-protected GMO rice. GMO wheat, rice and potatoes will not feed the world - but they could contribute significantly to that effort.  The question of whether to commercialize these GMO versions of these crops is going to be on the table in the not too distant future.  Regulators, food companies and consumers are going to have to wrestle with the issue.  Careful studies like this one will help to make that a better informed discussion.

Wheat image by Dag Endresen
You are invited to comment here and/or to email me at


  1. Has the review been published yet and under what title/authors? Thanks, John Blue

  2. John,

    The authors are:
    Snell Chelseaa, Bernheim Audeb, Bergé Jean-Baptistec, Kuntz Marceld, Pascal Gérarde, Paris Alainf, Agnès E. Ricrochb, ,

    Here is the link to the publication, available on-line, in print soon

    I wrote to the corresponding author listed there and she provided a preprint in pdf

    Here is a link to one of the author's blog

  3. Great post, but I think for many (including me) there are still lingering worries about widespread GMO application. I'd really like to hear your opinion on two particular issues:

    1) The red queen hypothesis. Are the studies long-enough to prove that horizontal gene transfer and pest adaptions are a moot point? For example, a study in the corn belt shows increased resistance to Bt corn exhibited by the corn rootworm (Gassmann et al. 2011 - Field-Evolved Resistance to Bt Maize by Western Corn Rootworm. DOI: 10.1371/journal.pone.0022629).
    This resistance was clearly evolved over a longer time-frame than what was studied in the articles you cite above.

    2) Social. I'm no expert in these matters, but given recent world events does it make sense to centralize control of food products to only a few corporate entities? I think this is probably the biggest concern. Even if the science holds up I think people are concerned about increasing corporate control of their food sources.

    1. How does it centralize control to corporations any more than how things are currently? GMO crops can be grown anywhere, by anyone, you just need the seeds. Just like regular crops - you still need to buy the seeds from somewhere.

  4. Ian,
    Gene transfer and pest adaptations are not new issues with GM crops since the same, natural mechanisms apply. For instance, if you are a wheat grower contracted to grow a specialty wheat, you have to get new seed each year because your own saved seed will have become genetically mixed with any other varieties growing in the area. For many crops, seed has to be grown with a degree of isolation to be pure. Pests have become resistant to crops that were immune through conventional breeding. Pests have become resistant to chemical and biological agents used to control them. Pests have become resistant to some GM traits. It is just the nature of things and the industry works to prevent resistance as long as possible, but also to find new tools over time.

    The issue of "corporate control" of the food supply is, I believe, over-blown. Monsanto or Pioneer have sometimes had a big part of certain seed markets, but they have always had competitors and can only succeed if they provide things that thousands of independent farmer find valuable. Patents expire. New options become competitive. The degree of consolidation in ag is actually not as great as in many industries. The point of greatest consolidation in food is actually at places like grain trading or food retailing. There is a big difference between farmers widely adopting a technology and "control." Farmers are fiercely independent folks, and the ones that survive this challenging business are only the ones that buy products that really help them.

  5. Thank you for this hysteria-free review. This issue is one that needs to be approached with common sense, not fear. I have many friends who have bought into the anti-GMO mania and would much rather be fully informed before I go rushing down the street screeching about how the sky is falling.


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