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What if GMO plants evolve into a negative outcome?

Submitted by: Wilbur Helsel


Expert response from Wayne Parrott

Professor, Crop Breeding and Genetics, University of Georgia

Thursday, 12/04/2018 16:19

Anyone who has traveled through the Southeast and seen kudzu vines along the highway knows that plants can evolve into a negative outcome. There is a similar concern that a GMO can produce negative outcomes in the environment. 

Therefore, prior to approving their commercial planting, GMOs must be tested in contained field trials to ensure that they do not behave in ways that could cause problems. To prevent negative outcomes, GMOs must not have the ability to cross with wild relatives, show weedy tendencies, or the ability to harm wildlife, among other criteria.

The issue gets more complicated because damage can take a very long time before showing up. Obviously, decades-long field trials are not practical prior to approval, so safety must be inferred. Humans have been altering plants for thousands of years. In fact, the type of intentional changes made in GMOs merely mimic the random, natural changes made over the thousands of years of domestication. Thus, the odds that a GMO will go on to have negative outcomes are about the same as the odds that a conventionally modified plant will go on and have negative outcomes. So, if a given change has not led to negative outcomes in a crop after decades of use, it is highly unlikely that the same change in a GMO will cause problems simply because it was made in a different way. 

At the end of the day, despite the fact that humans have been modifying plants conventionally for thousands of years, only a very few of these changes have gone on to have negative outcomes. That means that while the probability of long-term negative outcomes from GMOs is not zero, it is still too low to measure.