Whats the longest study done on how GMOs affect the longevity and overall health to human beings?

Expert response from Bruce M. Chassy

Professor Emeritus of Food Safety and Nutritional Sciences, Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign

Wednesday, 11/03/2015 17:56

The first thing to point out is that almost no safety studies are done in humans.  It's unethical to expose a human to an untested product of any kind, but more importantly, humans are just plain lousy experimental animals.  We are genetically heterogeneous, we don't follow protocols well, we grow and reproduce slowly, experiments on humans would be very expensive, and as we age a high percentage of us develop one or more diseases of aging that would confound the results (i.e. various cancers, circulatory diseases, arthritis, diabetes, etc.).  Fortunately, scientists in many fields have been able to develop animal model systems that allow potential human responses to be evaluated.  Animal experiments are used to evaluate nutritional value, pharmaceuticals, and potential toxic effects of chemicals, among many other uses.

Most people believe in fact that a well conducted sufficiently large and lengthy animal study is the best way to determine if a food is healthy for us or if a new drug is efficacious.  Animal studies are viewed as a sort of “gold standard.”  Animal studies have also been used in an attempt to assess the safety of GM crops which seems like a good thing since it would be virtually impossible to design and conduct a meaningful human feeding study with GM crops for the reasons mentioned above.  Hundreds of what are called whole food feeding studies have been done with GM crops -- in fact every GM crop is studied in several species of animal before it is approved.  Since many countries have their own independent approval systems for GM crops this means a lot of animal studies have been performed.  Most of these have been 90-day studies designed in the same way as the studies that toxicologists use to evaluate the potential toxicity of chemicals.  Decades of experience has shown that 90-days is sufficient time to evaluate safety in a rat or mouse.  None of these studies has ever produced any evidence of potential harm by GM crops.  A hand full of studies have made claims of potential harm but they were poorly designed and conducted.  Independent researchers and regulators have examined all animal studies and have concluded GM crops and non-GM crops are equivalent in risk and benefit. GM crops have also been tested in and fed to production farm animals, fish and poultry for more than 15 years without any observable adverse effect (A. L. Van Eenennaamand A. E. Young, 2014).

To return to the question about longer term studies, by 2012 (Snell et al. 2012) 24 longer term studies were completed.  Half of these were two year rodent studies and the other half were multi-generational studies of  two to five generations.  None revealed any adverse effect of long term feeding of GM crops.  It's worth noting that anti-GM activists have claimed that long term studies have never been done.  That's simply not true.

The answer could end here but I would be remiss if I didn't point out that for many reasons whole food animal studies are not very useful (Batholomeaus et al, 2013).  Animal studies work well for single pure chemicals, nutrients, or pharmaceuticals but foods are complex mixtures of highly variable composition.  There are many complicated reasons why we shouldn't conduct or trust animal studies done on whole foods; it may even be unethical to use animals for such weak and pointless studies.  Remember that the composition of GM foods is carefully evaluated and a number of other rigorous studies are required for safety approval.  It's also important to recognize that the U.S. National Academy of Science (and similar academies the world over), the American Medical Association (as well as those in Germany, France, the UK and elsewhere around the globe), the FAO, the WHO, and scores of scientific societies have all come to the conclusion that GM crops are as safe as any other and, more importantly, there is no scientific reason to expect them to be any different.

I know there are a lot of groups and a lot websites out there claiming all sorts of harms and dangers from GM crops but they lack evidence, provide flawed evidence, and make up evidence.  The science just doesn't support them.  They may be very good scaremongers--many of them may be sincerely afraid of GM crops--but they have gotten the science wrong.  

For more information, see these links:

• http://gmoanswers.com/ask/are-there-any-long-term-30-years-studies-done-full-spectrum-ecological-impact-transgenic-gmo.
• http://gmoanswers.com/studies/top-10-long-term-gmo-health-studies
• http://gmoanswers.com/ask/why-has-there-never-been-clinically-controlled-independent-human-feeding-trial-if-i-were-come