Genetically engineered (GE) foods are in the headlines again. Last month, a controversial French study claimed that a particular strain of GE corn causes cancer in lab rats. And in next week’s election, Californians will vote on Proposition 37, which aims to require labeling for all genetically engineered foods.
So do GE foods truly pose a health threat to humans? Does mandatory GE labeling make sense? We take a look at what the science says.
The Lowdown on Genetically Engineered Foods
GE foods are often referred to as genetically modified organisms (GMOs), but that term is incorrect, explains Alison Van Eenennaam, Ph.D., a genomicist and biotechnologist at the University of California, Davis. All foods have been genetically modified in some way, whether through engineering in a lab or through traditional selective breeding in the field.
GE foods have been genetically altered to give them a new, favorable characteristic, including pest or viral resistance or an improved nutrition profile. In some cases, scientists splice in DNA from another species that codes for a beneficial trait. In others, specific genes are essentially turned off so that they don’t code for an unwanted trait.
For now, the only GE foods on the market are plants and microbes. Commercial GE plants include pest- or herbicide-resistant crops, such as corn and soy, and viral-resistant papaya and zucchini. GE microbes include an engineered curdling agent for vegetarian cheese to replace rennin, an enzyme that comes from the stomachs of cud-chewing animals used to make some cheeses, as well as engineered yeasts used to ferment some wines.
Today, the most widespread GE foods are pest- and herbicide-resistant crops, according to Van Eenennaam, which mainly come from multinational corporations including Monsanto, DuPont and Syngenta. And for now, these are the GE foods that have stirred up the biggest controversy.
The most common pest-resistant crops have been modified with bits of DNA from Bacillus thuringiensis (Bt), bacteria that naturally produce proteins that are fatal to a specific group of insects, including major crop pests, but are not toxic to mammals. Bt-based insecticides have been used in both conventional and organic farming since the 1950s in the U.S. and are still sprayed on crops today.
The most common herbicide-resistant plants also include major crops such as corn and soy. These have been genetically altered to withstand a specific type of herbicide (mostly Roundup Ready), which kills weeds while leaving the crop alive. Between 75 and 80 percent of processed foods in the U.S. include some sort of GE crop, according to the Grocery Manufacturers Association
What’s the Worry?
When it comes to health and GE foods, most consumers are worried about the possibility of allergens or toxins. Many also have concerns over the crops’ environmental impact or have a general distrust of the multinational corporations that control the crops (but those are topics for another time).
Allergic reactions and toxicity are also the main concerns both for the scientists who develop new GE foods and those who study food allergies and toxins, explains Bruce Chassy, Ph.D., a food scientist and professor emeritus at the University of Illinois at Urbana-Champaign. All plant breeding, whether engineered or conventional, poses the risk of producing a plant that is allergenic, toxic or has other unwanted traits, according to a 2004 National Academy of Sciences (NAS) report on GE foods and human health, which ultimately determined that GE crops are safe.
But GE crops must jump through regulatory hoops that conventional crops do not, which means potentially dangerous traits are weeded out, making GE “the most researched and regulated food on the market,” says Chassy.
Over the past two decades, adds Chassy, hundreds of studies have convinced major scientific societies including the NAS and the American Medical Association that GE crops “pose no new or different risks than any other crop, and there is no scientific reason to believe they would be any more risky.”
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