THE DETAILS: Herbicide-tolerant crops include soybeans, corn, and cotton that are engineered to resist weed-killing chemicals. The report states that nearly all herbicide-tolerant crops planted today are "Roundup Ready," meaning they resist the effects of the glyphosate-based herbicide Roundup, made by the company Monsanto (which also produces most of the GE seeds on the market today). It also looked at "Bt crops," cotton and corn bred to contain a natural bacterium Bacillus thuringiensis that kills some types of insects.
Researchers at The Organic Center used U.S. Department of Agriculture surveys on herbicide, insecticide, and fungicide use from the last 13 years (the period since genetically engineered crops were first planted), as well as pesticide information collected from Monsanto. Herbicide-tolerant crops accounted for 72 percent of all the "trait acres" (acres with a crop containing one GE trait) planted with genetically engineered seeds between 1996 and 2008, they found. While the Bt crops led to a consistent year-over-year reduction in insecticide use, herbicide-tolerant cotton boosted herbicide use by significant amounts. In 2007, cotton farmers were using 200 percent more Roundup on their crops than they were in 1996, at an average annual increase of 18 percent, while soybean farmers were using 98 percent more (a 10 percent annual increase) and corn farmers 39 percent more (a 5 percent annual increase; herbicide-tolerant corn was adopted more slowly than other GE crops). At the same time, researchers noted, farmers who were growing conventional (not genetically engineered) soybeans and corn saw downward trends in the amounts of herbicides needed, using 26 percent fewer pounds of pesticides than farmers of genetically engineered crops.
A large portion of the increases in use have to do with the rise in glyphosate-resistant weeds that were virtually unheard of before genetically engineered crops were invented, the authors write. For 22 years after glyphosate was invented, no resistant weeds were documented, but in 1998, the first, rigid ryegrass, appeared in California almond orchards, and since then, nine more resistant species have infested cropland in 22 states. Farmers either have to raise the dosage of herbicides they use or come up with other ways to eliminate resistant weeds, like literally pulling them out by hand.
WHAT IT MEANS: Widespread use of pesticide resistant, genetically engineered crops has led to the rise of pesticide-resistant weeds—and, consequently, to higher does of pesticides being dumped in the environment. For a while, glyphosate was considered a "relatively nontoxic" herbicide that was harmful to wildlife but relatively safe to use around humans. However, recent studies have shown that very low levels of the ingredient can have subtle but adverse affects on soil quality and wildlife, and that the inert ingredients (the other ingredients in a product’s formula that help glyphosate penetrate weeds) increase the toxic effects of the chemical. Furthermore, farmers dealing with glyphosate-resistant weeds may opt for more potent herbicides, such as 2,4-D, a chemical that has been linked to non-Hodgkin's lymphoma and insulin resistance.
Previous studies by biotech firms have pointed to an overall decline in the number of pesticides being used worldwide thanks to genetically engineered crops, but those estimates may seem rosier than they are. "It is true that average application rates are declining, but the number of applications and the number of active ingredients applied is rising," says the author's report Charles Benbrook, PhD, chief scientist at The Organic Center.
For its part, the trade-group Biotechnology Industry Organization, which represents Monsanto and other biotech firms, released a statement in response to this report, saying that biotech crops have allowed farmers to adopt no- and reduced-tillage systems that "deliver important benefits in the form of improved soil health and water retention, reduced runoff, fuel conservation, reduced greenhouse-gas emissions and more efficient carbon storage in the soil."
Benbrook counters that a well-managed, rotation-based system with legumes and cover crops, and appropriate minimum tillage, is more effective. "We know how to manage resistance, although never with 100 percent certainty," Benbrook says. "Had the biotech industry, and especially Monsanto, taken the threat of resistance seriously, I am certain it could have been largely avoided, and today's slow-motion train wreck could have been avoided."
Buying USDA-certified organic food is the only way to ensure you aren't supporting genetically engineered crops; you can also patronize local farmers whom you can ask about their growing methods.