based upon the detection of as few as one bacterial cell. To alleviate suspicions that the DNA "fingerprints" Lyonnaise des Eaux and bioMerieux intend to use to identify microorganisms could be tripped up by dead organisms, the companies also plan to encode their chip so it recognizes RNA material that only living entities can synthesize. This ability also might enable the technology to detect RNA viruses such as the Norwalk and Polio viruses, Berger noted. However, although many of the pathogens' DNA fingerprints have been identified, Lyonnaise des Eaux and bioMerieux will need to sleuth out corresponding RNA fingerprints in order to achieve this goal, Renaud admitted. To comply with EPA's regulations, the technology will have to be sensitive enough to detect the RNA from a single organism, Berger said. The challenge of creating software to interpret the chip's signals is also formidable, Renaud said. Her company began working on this technology, which is akin to combinatorial chemistry, seven years ago, she said. After the technology distinguishes a pathogen's DNA or RNA fingerprint, it must "amplify" the genetic material by making copies of it. The amplified DNA or RNA is then labeled with a fluorescent material and put in contact with the DNA chip to cause a hybridization reaction that makes the chip glow in characteristic patterns. Working in conjunction with a laser scanner, the software must be able to interpret die intensity of this glow in making its identifications. Once the prototype chip is developed, Renaud said she expects it will require three years of industrial development through beta testing. Her company expected to begin conducting the tests required to approve the technology for use throughout the world as "soon as we are confident of the technology." Berger predicted that it would take at least 16 mondis from that point before EPA could approve the technology for use in the United States. —KELLYN S. BETTS
Bt pollen study casts doubt on plant safety as EU halts approval of genetically modified corn Despite mixed reviews from entomologists, a laboratory-based study suggesting that genetically altered corn might threaten monarch butterflies has regulators and researchers scrambling to determine its real-world implications. While U.S. scientists in government, industry, and universities estimate they can determine sometime this fall whether a significant environmental threat to butterflies exists, the European Union (EU) immediately froze approval of a type of genetically modified corn on the basis of this study. In May, Cornell researchers reported that monarch caterpillars either die or have stunted growth when they eat milkweed leaves dusted wim pollen from corn that is genetically engineered to contain genes from bacteria known as Bacillus thuringiensis (Bt). The Bt corn produces toxins that kill European corn borers, caterpillars that eat corn plants. "This study [regarding threats to nontarget species] has brought up an important issue that had been ignored by regulatory staff and needs attention," said Fred Gould, an insect geneticist at the University of North Carolina-Raleigh. Gould is also on the National Research Council committee that is currently evaluating the environmental risks and benefits of transgenic crops.
"Extensive follow-up" is needed before regulator conclude that engineered plants harm nontarget species, entomologists warn.
But other entomologists say that regulators are overreacting to a "very preliminary" report. "Policy makers are in danger of making hasty decisions regarding the implications of a lab-based study," said Anthony Shelton, assistant director of research at Cornell's entomology department. Bt corn offers an environmentally benign way to control the European corn borer, a major pest whose damages to corn are estimated at $1.2 billion per year, according to Shelton. "This preliminary study requires extensive follow-up," cau-
DID YOU KNOW? Exhausting news: Exhaust from two hours ofjet skiing is equivalent to the smogforming emissions from a 1998 passenger car operated for about 130,000 miles. About 30% of a jet ski's fuel escapes into the air and water. (Source: Calif. Air Resources Board)
AUGUST 1, 1999 / ENVIRONMENTAL SCIENCE & TECHNOLOGY / NEWS • 3 0 1 A
tioned Rich Hellmich, a U.S. Department of Agriculture (USDA) research entomologist at the Agriculture Research Service in Ames, Iowa. "It is one tiny part of a long sequence of complex biological and ecological interactions that would all have to fall into place for there to be a significant problem," he said. The laboratory study, which was published in Nature on May 20, was conducted by John Losey and colleagues at Cornell University. They demonstrated that wind-borne pollen from a transgenic plant can harm nonpest species. Their finding has tapped into the growing controversy over the potential benefits and damages created by genetically engineered crops (ES&T 1999, 33(9), 186A-187A). In Europe, where the debate is the loudest, the European Union immediately froze approval of a type of genetically modified corn on the basis of this study. As ES&Twent to press, EU ministers announced an intention to impose a virtual moratorium on the approved of genetically modified plants and foods until new rules can be devised. In the United States, EPA officials maintain they are rushing to answer this question. But those involved declined to elaborate further. EPA and USDA officials have gathered a group of researchers to plot a strategy for assessing the study's real-world significance, said an EPA spokesperson. "This laboratory study is an important piece of information. We need to get to the bottom of this as soon as possible," he added. The agency is also using
Pesky corn borer steers clear of Bt crop.
its authority to call in any relevant data from biotechnology companies. In the laboratory experiment, the caterpillars had no choice but to eat Bt pollen. In the field, researchers are studying how much pollen occurs on milkweed plants, and at what amount Bt pollen adversely affects the caterpillars. A key question is whether caterpillars have the choice to seek out or avoid Bt-tainted pollen. "We should have preliminary answers to these questions by the end of this field season," Losey said. Prior to the Cornell research, almost every study suggested that Bt corn has a minimal effect on wildlife and beneficial insects. Three insect predators that eat European corn borers also eat corn pollen; however, laboratory and field tests indicated that Bt pollen did not affect them. Only one other study published in Environmental Entomology in April 1998 indicated an effect on nontarget species. Lab
experiments by Angelika Hilbeck at the Swiss Federal Research Station for Agroecology and Agriculture in Zurich showed that green lacewing larvae that ate Bt-intoxicated corn borer caterpillars suffered higher mortality. Most previous studies looked for direct effects and did not find them, Losey said. The Cornell group and the Swiss researchers instead looked at more complex interactions, and that is where the effects are borne out, he said. The effects of Bt pollen on monarchs in the field eventually need to be compared to the effects of pesticides or other treatment methods. But this comparison could prove to be tricky. On a field-by-field basis, entomologists agree that the risks of Bt corn will be less than the risks of using existing pesticides. But in the past, pesticides were used on less than 10% of U.S. field corn. "If we compare the effects on monarchs and other butterflies of millions of acres of Bt corn with the effects of what was previously untreated acreage, we may find that the effects of Bt are significant," said Losey. He is also looking for other butterflies and moths likely to be affected by Bt corn pollen. Even if Bt corn pollen does prove a threat to monarchs or other butterflies, there are other solutions to this dilemma besides abandoning the transgenic plants, Shelton said. Plants can be genetically engineered to express less toxin in the pollen, or fields of Bt corn can be surrounded by perimeter plantings of non-Bt corn. —REBECCA RENNER
DID YOU KNOW? Infectious diseases: Currently, about half of the world's population is at risk of contracting serious infectious diseases. Annually, about 50 million people contract dengue fever; 300-500 million people contract malaria; 117 million contract lymphatic filariasis; and 200 million contract schistosomiasis. It is considered either very or highly likely that infection rates of malaria, dengue fever, and schistosomiasis will be altered by climate change. (Source: World Health Organization as cited in Environ. Health Perspect. 1999, 107(5), 329-337) 3 0 2 A • AUGUST 1, 1999 / ENVIRONMENTAL SCIENCE & TECHNOLOGY / NEWS
