Better eating through biotechnology conjures up a cornucopia of firm tomatoes, rosy radicchio and enriched rice. But some consumer groups are raising questions about the health risks of eating genetically modified foods.
The potential for unpredictable allergic reactions is the most immediate issue. Harder to quantify is the risk that new genes could spread beyond their target crop into people or into microbes, giving old germs new virulence.
Already genetically modified foods are braided into the food chain: About 55% of soybeans and 30% of corn are modified. U.S. Food and Drug Administration review is voluntary, not mandatory. In addition, labels identifying genetically modified foods per se aren't required, though any food known to trigger allergies must carry a warning.
The risk of allergic reactions went from hypothetical to real in 1996, when food scientist Steven Taylor of the University of Nebraska found that soybeans modified to contain genes from Brazil nuts triggered reactions. The soybeans, developed by Pioneer Hi-Bred International of Des Moines, were designed to take advantage of the nuts' high-protein content. But they triggered positive blood and skin-prick tests, Dr. Taylor reported in the New England Journal of Medicine.
Pioneer Hi-Bred abandoned that project. The incident leaves some consumers uneasy, but Pioneer believes its response shows that health safeguards work. "Our policy is that if there's potential for allergenicity, we discontinue that product immediately," says a spokesman. Of the tens of thousands of biotech experiments under way, Dr. Taylor says he has heard of few with similar allergic potential, and none have made it to market. But exotic new gene blends keep the issue alive.
The latest example is "golden rice," a strain engineered by Swiss scientists with new genes that produce iron and beta carotene. Envisioned as a staple crop to fight famine, the rice draws its nutritional muscle and yellow hue from genes taken from bacteria, fungi and daffodils. Daffodils also contain plant toxins and provoke skin sensitivity called "daffodil itch," says the Physicians Desk Reference for Herbal Medicines. Nobody has implicated the specific genes used in golden rice. But Dr. Taylor says it's a question researchers must answer.
Golden rice developers at the Swiss Federal Institute of Technology in Zurich promise to do health assessments before distributing any rice. And the project's sponsors at the Rockefeller Foundation in New York "want to use the beta carotene rice as a model of how you investigate" health risks, says foundation microbiologist Gary Toenniessen.
Meanwhile, most of the 40 or so genetically modified food crops passing the FDA's voluntary review weren't engineered to boost nutritional content. Instead, they're supposed to boost yields by increasing resistance to insects or to weed killers like Roundup.
But some critics charge that such traits could make food crops less nutritious or even harmful. In a controversial study last summer in the Journal of Medicinal Foods, author-activist Marc Lappe charged Roundup-resistant soybeans had 12% to 14% lower levels of nutrients called isoflavones. In response, manufacturer Monsanto Co. cited American Soybean Association figures showing that these nutrients fluctuate by 300% even in natural soybean strains. And more recently, European scientists in the journal Lancet argued that a diet of genetically modified potatoes damaged the stomachs of test rats. Skeptics countered that the study was small and poorly controlled.
Genes that confer antibiotic resistance and are used as markers in genetically modified plants have also caused concern. At issue is whether such resistance could spread. Consumer's Union has called on companies to stop using such genes. The FDA calls the risk of spread remote.
Unlike some European countries, U.S. law doesn't require genetically modified foods to be labeled for consumers. But any food -- modified or traditional -- with the potential to cause allergic reactions must be labeled, especially food with genes from such traditional culprits as eggs, milk, wheat, fish, shellfish, tree nuts, soybeans and peanuts.
"If there's a gene from those sources, the presumption is that food should be labeled," says James Maryanski, biotechnology coordinator for the FDA's Center for Food Safety and Applied Nutrition. Less predictable is the allergic potential of the genes from bacteria and viruses, he adds. In such cases, scientists must rely on chemical analysis of heat stability or resistance to stomach acid -- the telltale signs of an allergen -- for clues.
Basically, FDA policy rests on the assumption that crops that are modified in the lab aren't substantially different from farm-bred hybrids. But in contrast to tangelos and nectarines, modern genetically modified foods mix genes from unrelated species -- say, bacteria with soybeans. Still, Dr. Maryanski says, "these genes perform as expected. Even though they come from diverse organisms, they're not as different as they sound."
The FDA asks companies to consult with it voluntarily and to share a summary of their safety data. Some think that isn't enough. The Consumers Union, among others, has called for mandatory safety reviews. Voluntary labeling of genetically modified food by companies is one possible compromise, but critics note that the trickledown effect into processed foods will be hard to track and quantify.
In coming weeks, the FDA is holding public meetings on genetically modified foods in Chicago, Washington and Oakland, Calif. Consumers hungry for details of federal policy can dig into the food biotech pages at www.fda.gov and www.usda.gov.
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