Biotech crops' seal of safety does not convince skeptics.

G enetically modified organisms (GMOs) have become nearly ubiquitous in U.S.-produced corn, soybeans, and canola, and more than twothirds of the processed foods Americans consume contain such ingredients. Government agencies and international bodies have repeatedly approved the foods for human consumption while arguing that such bioengineered crops help preserve the environment and could save millions from hunger. Yet many consumers and some scientists remain skeptical, particularly in Europe. GMOs’ skeptics worry that prolonged exposure to such foods promotes allergies and even cancer. Hundreds and some say thousands of studies have examined the health effects of bioengineered products, most concluding that GMOs are as wholesome as other foods, persuading 60 countries to approve the importation of genetically engineered crops for food or animal feed and 29 led by the U.S. to allow their production, according to the International Service for the Acquisition of Agri-biotech Applica tions (ISAAA)—a nonprofit group that encourages using GMOs to alleviate hunger and poverty. The World Health Orga nization, the National Academies, and the European Commis sion describe them to be as safe as their conventional counterparts, helping worldwide market growth for biotech foods to reach $160 billion. But doubts persist. Opponents and those merely urging caution point to a few studies—which biotechnology backers discount—indicating cancerous or other effects in rats. The lingering concerns have prompted countries, including Germany, France, Peru, and a county in California to ban the crops and have led to labeling campaigns, such as those in Europe, to give consumers the option to avoid foods containing such organisms. A chief complaint about the research declaring GMOs safe is that the studies are too short to assess the long-term toxic effects of consuming foods genetically manipulated to promote herbicide tolerance, insect resistance, or other traits, and that longer-term studies are needed to truly demonstrate safety. In 1992, the U.S. Food and Drug Administration called foods containing ingredients derived from the recombinant DNA technology used to make GMOs “substantially similar” to conventional ones and deemed them “generally recognized as safe.” Since then, proponents and government agencies have insisted that the more extensive tests required for drugs or pesticides aren’t necessary. Only a latent trend—such as an inexplicable spike in cancer rates—could signal that consuming GMOs over several decades may lead to health problems stemming from the buildup of toxins in the body.