What are the arguments against genetically modified crops?

Illuminating answers to environmental questions.
May 18 2010 7:10 AM

Seeds of Discontent

Should environmentalists just say no to GMOs?

Illustration by Mark Alan Stamaty. Click image to expand.

Green Lantern, what's your take on genetically modified crops? Should environmentalists be up in arms about them or not?

As one representative from the organic sector put it, agricultural biotechnology is kind of like the Force: It's not inherently good or bad—what matters is how you use it. Still, green-minded consumers have found plenty of reasons to worry that genetically modified crops will lead us to the dark side. As global G.M. acreage continues to grow, those are well worth considering.

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Plenty of folks can't get past the fact that genetic engineering sounds creepy on its face. But every kind of crop breeding involves the manipulation of a plant's genetic material. We can adjust a plant's DNA by selecting parents with desirable traits or cross-pollinating related organisms. But conventional (i.e., non-G.M.) practice includes some pretty unnatural-sounding methods, too—such as bombarding seeds with radiation or chemicals so they mutate faster than normal or using Petri dishes to help create hybrids. Are these tricks more "natural" than genetic engineering, in which scientists selectively isolate genes from one organism and insert them into another? It's an interesting debate, but one that seems moot to the Lantern: After all, "natural" isn't always synonymous with "good" or even "good for the planet."

The Lantern is more swayed by the socioeconomic argument against genetically modified crops. For example, many people are deeply uncomfortable with the fact that a handful of massive corporations, such as Monsanto, control a wide swath of the market and impose strict intellectual property-regulations. Others worry that undue focus on genetic engineering takes time, energy, and funding away from other research areas—like organic farming. These concerns belong in any well-rounded discussion of the perils and promises of genetic engineering, but the fact that G.M. crops have been implemented in some troubling ways isn't a good reason to reject them altogether.

What about environmental problems? Some worry that pollen from genetically engineered crops will float off the farm and mingle with other plants to create new hybrids—a phenomenon known as gene flow. Gene flow can occur with any kind of plant, bred in any manner, and it's not always a bad thing. But some G.M. crops on the market conjure up troubling ecological scenarios. To date, the vast majority are engineered to tolerate weed-killing chemicals or produce their own pesticides. Plants that gain the former ability through gene flow could become so-called "superweeds." Meanwhile, wild plants that become able to produce their own pesticides might alter their local ecosystem by damaging insect populations.  

As this fact sheet (PDF) from the Pew Initiative on Food and Biotechnology makes clear, a whole lot of things need to line up correctly in order for gene flow to happen and for that gene flow to have negative consequences. According to a recent report from the National Research Council, gene flow hasn't been a major problem in the United States because the crops that make up the lion's share of our GMO acreage either don't have compatible wild or weedy relatives on U.S. soil (corn, soybeans) or else their relatives are highly localized and therefore easy to avoid (cotton). However, that doesn't mean that future G.M. crops won't need to be strictly contained or that those three cash crops won't cause problems in other countries.

The NRC report actually suggests that environmentalists should be feeling pretty rosy about G.M. crops. It concludes that they're providing American farmers with "substantial" net environmental and economic benefits over conventional crops, including lower production costs, fewer pest problems, reduced use of pesticides, and better yields. At the same time, the report offered some significant caveats, noting that these benefits aren't universal and may decline over time, and that both benefits and risks may increase as more and more farms adopt the technology.

The report did flag one issue that's been a major concern to environmentalists: The likelihood that herbicide-tolerant crops will lead to herbicide-resistant weeds. Most crops of this kind have been bred to withstand glyphosate, a broad-spectrum weed-killer that's much less damaging to animals, soil, and water than some of its counterparts. (You may know it by the brand name Roundup.) Ideally, these engineered crops allow farmers to shift away from the harder stuff, benefiting both the environment and farm workers. They can also help cut back on tillage, which can improve soil health, reduce water pollution, and limit greenhouse gas emissions.

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