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Despite the public controversy over the safety of genetically modified organisms (GMOs), in the scientific community the controversy is considered misplaced. The National Academy of Sciences has reviewed the safety of GMOs twice, once in 2000 and again in 2004. Both reviews concluded that genetically modified crops pose no threat to human health (though the reports noted that GMOs do have the potential to create allergens that might alter the nutritional quality of food).
However, herbicide resistance is the main characteristic that the biotech industry has introduced into plants to enable greater tolerance to increased levels of herbicides like glyphosate ("Roundup"). As a result, there have been significant increases in the amounts and numbers of herbicides used in growing genetically modified crops (the vast majority of corn and soybeans grown in the U.S., for example, are genetically modified).
The problem with this is that the International Agency for Research on Cancer (IARC) has classified Roundup as a "probable human carcinogen" and another commonly used herbicide, 2,4-dichlorophenoxyacetic acid as a "possible human carcinogen."
The use of Roundup has increased from 0.4 million kg in 1974 to 113 million kg in 2014. As a result, Roundup-resistant weeds have emerged as a major problem and are now found on nearly 100 million acres in 36 states in the U.S. So fields are now often treated with multiple herbicides, including 2,4-dichlorophenoxyacetic acid. In 2014, the EPA approved a new product called Enlist Duo, which contains both glyphosate and 2,4-dichlorophenoxyacetic acid (designed specifically to combat herbicide resistance) to be used in tandem with genetically modified seeds designed to resist herbicides.
Why did the EPA approve the use of these two substances? According to an article in the New England Journal of Medicine by Philip Landrigan, MD and Charles Benbrook, MD, the science used to evaluate the safety of Enlist Duo "predated current knowledge of low-dose, endrocrine-mediated, and epigenetic effects and weren't designed to detect them." Further, the IARC's determination the the two herbicides used in Enlist Duo are "probable" and "possible" carcinogens was only just made in 2015, after the EPA's ruling.
It's not clear how easy it is to rid our food of pesticides and herbicides by washing them. Some of these chemicals are "systemic," meaning they enter the plants on which they're sprayed and therefore cannot be removed by washing, while others are "non-systemic," meaning they stay on the surface of plants and can be removed by washing. It's even more complicated than that, however: Many "systemic" chemicals actually leave the plants if given the proper amount of time between spraying and harvesting. Unfortunately, glyphosate (Roundup) is systemic. According to an EPA report, "glyphosate residues can be found in food long after treatments have been made. For example, lettuce, carrots, and barley contained glyphosate residues at harvest when planted a year after treatment."
So what can the average consumer do about this? First, recognize that GMOs themselves are not the problem. Recognize also that many of the pesticides and herbicides used in U.S. crops likely pose an acceptable level of risk to human health. But recognize finally that it remains unclear what effects will be felt when Enlist Duo hits the market and an EPA-anticipated 3-to-7 fold increase in 2,4-dichlorophenoxyacetic acid results. Buying organic may be a good solution—as long as "organic" means specifically that no chemicals were used. Unfortunately, it seems this isn't always the case. If you want to be certain no pesticides or herbicides have been used on the food you buy, make sure the food you buy is specifically labeled as such. Unfortunately, however, few such foods are actually available. The best you might hope for without resorting to growing all your own food is to buy food grown with pesticides and/or herbicides that have been shown to be safe.
