When Science Gets in the Way of Pet Agendas

On June 11, the Centers for Disease Control and Prevention in Atlanta issued a report about StarLink corn.1 Remember StarLink? Marketed by Aventis Seeds, it contained a gene from the soil bacterium Bacillus thuringiensis, or Bt. The Cry9C protein encoded by the gene rendered the plants resistant to chewing insects. But unlike other varieties of Bt corn, StarLink was not approved for human consumption because of questions about potential allergenicity. Data provided to the Environmental Protection Agency (EPA) showed that Cry9C protein is not as quickly digested as other Bt proteins, potentially allowing more time for the body to make antibodies against it. The evidence was circumstantial, but EPA acted cautiously by approving StarLink for animal use only.2 EPA erred badly--in hindsight, it's not surprising that StarLink made its way into the human food stream. Last September, a genetic testing lab hired by environmental activists detected StarLink's DNA fingerprint in tacos distributed by Kraft Foods. A subsequent search led the Food and Drug Administration (FDA) to recall hundreds of corn products, and Aventis cringed at a clean up bill of $1 billion. The media went into a feeding frenzy and environmental groups like Greenpeace and Environmental Defense (ED) that are opposed to genetically modified crops had a field day. About 50 people claimed they were sickened after eating the corn. But did those people really react to Cry9C protein? Scientists agreed the possibility of an allergic response was slim. The levels of food borne Cry9C protein if any were low, and besides, it hadn't been around that long. You have to have been exposed to an antigen beforehand in order to react to it. Still, the feds wanted to be sure. So FDA asked CDC for help in studying the matter. From 51 complaints, the agencies culled 28 people whose symptoms and circumstances matched a food allergy, then examined blood samples from 17 of them. According to an immunoassay, none of the samples had IgE antibodies cross reacting with Cry9C. IgEs are key players in the chain of reactions leading to food allergies--no IgE, no reaction. In other words, if those people got sick, it wasn't because of Cry9C. As controls, CDC also examined blood from people with documented multiple allergies and banked samples drawn before 1996, when GM crops were first grown commercially. An independent testing laboratory confirmed the results. But biotech's critics weren't satisfied. ED issued a press release claiming "the results are far from definitive. º CDC and FDA only examined reactions of a small number of people who asked to be assessed." The group instead suggested mass screening of young children and food industry workers. But what better people to test than those already reporting allergies? They're the best sources of documentable evidence of harm. Other Agendas? ED says it advocates "solutions based on science, even when it leads in unfamiliar directions." But C.S. Prakash, director of the Center for Plant Biotechnology Research at Tuskegee University in Alabama, has doubts. Says Prakash, ED "readily debunks a study by the most respected public health organization in the world which finally puts the allergy question of StarLink corn to rest." Prakash thinks "no amount of scientific studies showing the safety of biotech crops would satisfy environmentalists because their opposition on human health and ecological grounds is a facade for anti-development and anti-corporate platforms." This isn't the first time science trumped complaints about GM crops. Take the firestorm over monarch butterflies two years ago. According to a brief report in Nature, pollen from corn transformed with another Bt gene kills monarch caterpillars.3 Once again, the press went into overdrive, with headlines such as 'Butterfly Killing Corn'. ED warned "it would be tragic if we fail to learn the lesson of DDT and devastate butterfly populations using genetically engineered crops." For some reason, though, everybody neglected evidence in favor of much larger threats to monarchs--habitat destruction and mass spraying with conventional pesticides. The bigger picture seemed like common sense at the time, but it took a sober assessment by ecologist David Pimentel and biodiversity champion Peter Raven to add the right dose of perspective.4 The EPA echoed Pimentel and Raven by concluding that, "considering the gains obviously achieved in the level of survival of populations of monarch butterflies and other insects by eliminating a large proportion of the pesticides applied to corn [and other GM foods].....the widespread cultivation of Bt crops may have huge benefits for monarch butterfly survival." After numerous follow-up studies, two Chicago meetings and an EPA advisory panel session in Washington--scientists concluded that Bt corn wasn't much of a problem. According to EPA, all factors "indicate a low probability for adverse effects of Bt corn on monarch larvae."5 Says ecologist Orley "Chip" Taylor, head of Monarch Watch at the University of Kansas in Lawrence, "the incidence of Bt toxin is pretty low to kill monarchs in the field." Biotech Not Alone Recently, Greepeace blamed President George W. Bush for hiding behind uncertainty in not supporting the Kyoto treaty on global warming. Bush claimed that evidence for warming was incomplete. Greenpeace's stand is puzzling, though. The organization also opposes agricultural biotechnology, and in doing so is a big fan of uncertainty, claiming all the evidence isn't in yet to justify approval. In the absence of absolute proof that they aren't harmful, "better safe than sorry' should rule by banning GM crops.6 Unfortunately, nothing is absolute in science, regardless of the hypothesis, theory, law or peeve. Greenpeace's philosophy is formally known as the 'precautionary principle,'7 but the 'what if' argument might be a better label. Bush's stand is equally strange. Scientific consensus has long pointed to the reality of global warming caused by greenhouse gases, but opponents insisted supporting data were incomplete--global warming could be just a blip on larger scale climatic variations. That may be true--and some experts still maintain as much--but carbon dioxide and methane are "more abundant now than at any time in the last 400,000 years," says the National Academy of Sciences about a report it just completed on the issue.8 Convened at White House request, a blue ribbon committee called for more study but concluded that global warming due to greenhouse gases "accurately reflects the current thinking of the scientific community," according to an NAS press release. This was old news to most climatologists, so why was Bush still skeptical? Lessons Science is the only way we reliably learn about the natural world. That's why it's also indispensable for judging important policy issues including biotechnology. But those who call on science should remember that it often fails to support pet ideas. Monarch scientist Chip Taylor thinks important ecological questions remain about certain GM crops, including those transformed with genes for herbicide tolerance. Spraying resistant corn with agents such as Roundup could kill milkweed plants that support monarch caterpillars. Taylor and colleagues hope to address these questions with more research, and eventually "bring policy makers up to speed, so when decisions are made at the political level we make them on the best information available." Barry A. Palevitz, (palevitz@dogwood.botany.uga.edu) is a professor in the department of botany at the University of Georgia and a contributing editor for The Scientist. This article is based on a commentary by this author in the Atlanta Journal-Constitution, June 24, 2001, page C1. References 1. National Center for Environmental Health, "Investigation of human health effects associated with potential exposure to genetically modified corn" Centers for Disease Control and Prevention, Washington, D.C., July 23, 2001, (www.cdc.gov/nceh/ehhe/Cry9cReport) 2. K. Devine, "GM food debate gets spicy," The Scientist, 14[21]:10, Oct. 30, 2000. 3. J. Losey et al., "Transgenic pollen harms monarch larvae," Nature, 399:214, 1999. 4. D. S. Pimentel and P.H. Raven, "Bt corn pollen impacts on nontarget lepidoptera: assessment of effects on nature," Proceedings of the National Academy of Sciences, 97:8198-8199, 2000. 5. Environmental Protection Agency, "Scientific advisory panel preliminary report," October 2000 (www.epa.gov/scipoly/sap/2000/ october/brad3_enviroassessment.pdf). 6. Greenpeace International, "Safe or Sorry--Precautionary Principle in the Biosafety Protocol," January, 2000. 7. K.R. Foster et al., "Science and the precautionary principle," Science, 288:979-81, 2000. 8. Committee on the Science of Climate Change, "Climate change science: An analysis of some key questions," National Research Council: Washington, D.C., 2001. (http://books.nap.edu/books/ 0309075742/html/)

When Science Gets in the Way of Pet Agendas

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