Scientists Critical of Argument for GM Crops

14 Aug, 2009

Genetic modification of crops has been controversial since it began over 20 years ago. In Europe and the UK, overwhelming consumer protest has resulted in a moratorium on genetically modified produce being sold, and in the US concerned health experts have pointed to the fact that there is limited testing for potentially dangerous health effects of genetically modified crops, and no requirement that they be labeled for consumers.

The Union of Concerned Scientists (UCS) has just released a report showing that one of the prime arguments for genetically modified crops—that GM technology will greatly increase yields—has not stood up under extensive testing in the United States. This is despite the millions that have been spent, much of it from government funding, for GM development.

“The industry and many of its supporters have often claimed over the years that genetically modified crops increase yield,” Doug Gurian-Sherman, senior scientist for the Union of Concerned Scientists’ Food & Environment Program and author of the new report, told Organic Connections. “Yield is a very important quantity to consider, especially in the context of the food crisis of the last few years. GM proponents have therefore used increased yield as a reason why we need to move forward with genetically engineered crops, to be able to produce enough food for the growing population. In the context of both the industry media campaigns and the growing population, we thought it was important to look at whether or not this common claim was actually proven by the data.”

The findings of the report show that yield has clearly not been increased by genetic modification. While corn and soybeans—the two food crops that have been genetically modified—did have a rise in yield in the twentieth and early twenty-first centuries, it was largely not as a result of GE traits but rather of successes in traditional breeding and other agricultural technologies.

Focusing in on corn, data from the United States Department of Agriculture shows that average corn production per acre nationwide over the last five years (2004–2008) was about 28 percent higher than for the five-year period 1991–1995. But UCS’s analysis of specific yield studies concluded that only 3 to 4 percent of that increase was attributable to genetic modification, leaving the remaining 24 to 25 percent due to other factors such as conventional breeding.

The report also found that organic and low-external-input farming methods, which use reduced amounts of fertilizer and pesticides compared to typical industrial crop production, generally produced yields comparable to those of conventional methods for growing corn or soybeans. For example, non-GE soybeans in recent low-external-input experiments produced yields 13 percent higher than GE soybeans.

Critics of the report have cited that it only focuses on the US—but there is a very good reason for that. “Some promoters of genetically engineered crops have said that we didn’t look at data from developing countries where the need is really the greatest,” said Gurian-Sherman. “The reason we limited ourselves to the US was because that is where these crops have been grown the longest, where we had the most and the best data, and where we could closely examine the actual contribution of genetic engineering versus other crop traits that are often overlooked when looking at yield in genetically engineered crops.”

Gurian-Sherman also remarked that only one or two types of genes are being implanted into a crop that consists of thousands of genes, many of which are important to yield. “It turns out that the conventional genetics of the crop are usually much more important to yield and productivity performance than the genetically engineered traits.”

While the report did not cover the effects of GM crops on human health, Gurian-Sherman pointed out the laxity of regulations and testing for such effects by government agencies. “The data that’s been used in the regulatory system is not very robust,” he said. “It’s not anywhere near what you would do for a new drug or chemical pesticide, for example. The real question is, is the regulatory system in the US adequate to reliably discover harmful applications of genetic engineering? In my opinion, it is not.”

The report concludes by recommending that the USDA, state and local agricultural agencies, and public and private universities should redirect substantial funding, research and incentives toward approaches that are proven and show more promise than genetic engineering for improving crop yields. The recommendation is also made that relevant regulatory agencies should develop and implement techniques to better identify and evaluate potentially harmful side effects of genetically engineered crops.

For more information, or to download a free copy of Failure to Yield, visit http://ucsusa.org/food_and_agriculture/science_and_impacts/science/failure-to-yield.html.