So far, there’s no good evidence that the foods on the market containing GMOs are any less safe than regular foods.
The mainstream view on safety: At this point, billions of people around the world have been eating GM foods for decades without any noticeable ill effects. And numerous scientific studies have concluded that the GM crops currently on the market pose no more of a health risk than conventional crops.
Here’s what the American Association for the Advancement of Science (AAAS) said in 2012: “The science is quite clear: crop improvement by the modern molecular techniques of biotechnology is safe.”
Likewise, in 2010, the European Commission reviewed a decade’s worth of independent research and concluded, “GMOs are not per se more risky than e.g. conventional plant breeding technologies.”
What that means: Traditional breeding techniques have long altered the genes of plants and animals. That’s a messy process. The risk of random mutations and unexpected outcomes has always been present. (To take one example, crop scientists have long used radiation on seeds to induce mutations and improve the odds of getting desired traits.)
So what most scientific advisory panels have concluded is that the risk of using genetic engineering to alter genes isn’t any riskier than conventional breeding when it comes to food safety.
The dissenters: A minority of scientists still insist, however, that more research is needed before GM foods can be definitively considered safe. After all, genetic engineering isn’t exactly like traditional breeding, and it may have downstream effects scientists haven’t fully studied.
For example, in a dissent to that AAAS statement, 21 researchers argued that increased herbicide use — which can occur with crops engineered to be resistant to Roundup — might have health effects we don’t yet know about. (That said, many “conventional” crops also require plenty of pesticides. This varies from crop to crop, and simply calling something “GMO” doesn’t necessarily tell you all you need to know.)
Allergies: Another common question has to do with allergies. Transplanting DNA from other organisms into crops has the potential to introduce new allergens into foods. Companies tend to test for specific allergens, but critics often argue that it’s impossible to test for all unknown allergens.
One counterpoint, however, is that many traditional foods also carry some risk of allergies, including foods imported from other countries, which receive far less screening. (See here for more on this debate.)