engage in studies to look for the negative impacts of those developments? He took issue with the language used in the session; for example, looking for indicators as warnings for negative impacts of GEOs, when, in fact, the effect may be neutral or positive.


It is hard to monitor without thinking about endpoints, suggested a participant. When designing a study to look at either pre-release risk assessment or post-release monitoring of transgenic fish, for example, it is hard to come up with indicators of impacts as the focus moves from the initial entry of an organism to its spread further into the environment. Different situations require direct measurements or indicators.

The speakers responded about some endpoints to look at from their research perspectives. Gepts suggested monitoring the wild relatives of crops, such as through GIS surveys, to see how they fare in the presence of transgenic crops. Larson said a matrix model may help predict potential invasive effects before a release is made, particularly in the area outside of a crop field. Marvier suggested looking at non-target effects, moving beyond the local release environment and the plant that has been manipulated.

Potential Bias

One participant expressed concern about potential biases in a meta-analysis if it relies on the available published literature. Marvier said she went beyond the published literature by using the Freedom of Information Act to get studies submitted by industry to the government for regulatory approvals.

Predictive Power

Larson was questioned about the ability to predict the invasiveness of a species that has not been previously introduced even if there is pre-invasion information about the species and the environment (but not the interaction); in fish, it is believed to be only about 70 percent. Larson said she did not think the percentage was any higher in plants. Thus, she said, invasive species studies do not provide the power of prediction that some regulators of GEOs might like, if it can be assumed that GEOs are likely to behave in the same way—an assumption that is subject to debate.

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