Also up for debate is whether glyphosate is harmful in the first place. Industry groups and independent scientists challenge WHO’s classification of glyphosate as “probably carcinogenic” to humans, pointing to a scarcity of evidence in its report along with other major studies that demonstrate the chemical’s safety. Environmental Protection Agency and European Food Safety Authority classify glyphosate as noncarcinogenic.
Would labeling affect herbicide use? Chipotle’s experience provides a cautionary tale. To go GMO-free, the restaurant chain says it switched to sunflower oil that wasn’t modified genetically from soybean oil that was. However, sunflowers are bred to be resistant to a different class of herbicides, Kniss says, and those chemicals are responsible for the development of more herbicide-resistant superweeds than glyphosate is. Chipotle’s nongenetically modified corn, meanwhile, is likely to be treated with a variety of other herbicides, including 2,4-D.
“By buying something that doesn’t have GMOs, that says nothing about whether or not that particular product has been treated with [chemicals],” Kniss says.
After interviewing 12 experts, we believe that non-GMO labels aren’t a reliable way to ensure that a food contains fewer chemicals than does a GMO variety. GMO-free, in other words, doesn’t mean herbicide-free.
PRICE TAGS. Since California introduced a ballot proposition in 2012 to mandate the labeling of genetically modified foods, the food industry has warned that a patchwork of state laws would lead to a spike in food prices. Companies would have to create state-specific labels, Gruber says. Products that are labeled to comply with one state’s laws inevitably would end up on shelves in another state that has different laws. Companies would have to pay fines for violating those laws, he says.
If food companies decide to avoid the headache by switching to non-GMO ingredients, operating costs would increase, because many non-GMO ingredients cost more than GMO varieties do, experts tell us. That’s because it costs more to grow non-GMO crops, and the yields typically are lower. Labeling opponents worry that companies will pass the increased costs on to consumers, which could result in as much as an extra $500 per year in grocery bills for a family of four, according to a Cornell University study.
Labeling advocates’ estimates range from less than $1 to just more than $15 per person per year.
A major reason for the discrepancy in the two estimates is that no one knows whether GMO labeling would change the way that Americans shop. For example, in Europe, strong anti-GMO sentiments and mandatory labeling (on any product that contains more than 0.9 percent GMO) make it nearly impossible to find genetically modified products in stores there.
What’s clear is that labeling has the potential to change behavior, Messer says. For example, the 2010 introduction of rBST-free (hormone-free) milk labels led to a rapid shift in the dairy aisles as shoppers made it clear that they preferred the labeled versions.
“My anticipation is that if GMO labeling is mandated, that will have a major impact on the market,” Messer says. “Consumers will be highly reluctant to purchase anything that says it contains GMOs.”
Transparency is good, but GMO labels won’t give consumers necessarily the information that they believe that they’re getting.
Emily Sohn has covered health and science issues for 15 years. She has written for Discovery News, Nature, the L.A. Times and the Washington Post.