Page 14

transgenic crops are introduced, baseline monitoring helps researchers to understand the systems into which genetically modified plants can be injected. For example, Power said, “it has been suggested for years that viruses are not likely to have any effect on natural plant populations, because most natural plants have evolved resistance to viruses. But there had been little quantitative information to address that question, and studies over the last couple of years have come up with more and more examples of naturally occurring viruses that have had substantial effects on naturally occurring plant populations. So we can no longer assume that there isn't going to be any effect of releasing these virus-resistant plants.” Without a baseline—that is, without knowing in some detail what is going on or what can go on in nature—it is difficult to make an informed judgment about the effects of genetically modified crops.

Getting the detailed baseline data that researchers need, Power said, will require extensive monitoring programs to watch for disease outbreaks or pest infestations in agricultural systems. “But we don't have such a program for natural ecological systems,” she said. “We have some long-term ecological research sites that are meant to begin this process, but these sites are only a decade or two old in most cases. So it is difficult to argue that the baseline monitoring data we have right now are sufficient for many of the kinds of ecological risks that we are interested in.”

One way to correct for having so few baseline data is to use control sites—areas where nontransgenic crops continue to be planted—and compare outcomes there with outcomes at sites where genetically modified crops are introduced. If that is done, the selection of appropriate control sites will be critical, noted Anne Kapuscinski, of the University of Minnesota. The control sites must be carefully matched to the release sites on the basis of key ecological variables, and they must be chosen so that inadvertent contamination from genetically modified crops is unlikely. “It is also going to be important to choose carefully which release sites to monitor," she said, "because it will not be feasible to monitor each commercial application of a genetically modified organism.”

Ultimately, the purpose of monitoring is to help one to understand the risks and benefits associated with transgenic crops and to be able to respond to or manage the risks effectively. So the monitoring should take into consideration the needs at two interconnected stages of risk decision-making, risk assessment and risk management.

Risk assessment has been defined in a variety of ways over the years, said Bob Frederick of the Environmental Protection Agency, but in essence it is an analytical tool that helps one organize and analyze large amounts of data to estimate the potential risk posed by a process or event of interest. Risk assessors attempt to calculate a numerical value for risk, a