"We filter out 10 to 15 species which we then examine in more detail."
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GMO Safety: Bt plants can have different effects on the ecosystem depending on the regions in which they are grown and how they are used agriculturally. Is it possible to conduct a risk assessment that takes into account the diversity of ecosystems? What can be studied in the laboratory and what must be studied in the field? Angelika Hilbeck: We can't model the diversity of ecosystems in the laboratory, but we can take individual key components of an ecosystem and examine them in the laboratory. Fundamental questions can be examined experimentally there, which is often difficult and more time-consuming and expensive to do in the field. For example, we can clarify the direct effects of the Bt protein on individual organisms. But even this is not always easy and largely depends on the chosen methodology. On the basis of findings in the laboratory or the climate chamber, we can then develop more specific questions and smarter test procedures for field studies. Laboratory findings must ultimately be supplemented by studies in the field. It is widely known, particularly from the development of GM plants, that organisms can behave differently in the laboratory and greenhouse than they do in the wild. GMO Safety: Surely this is a very time-consuming and expensive approach? Angelika Hilbeck: No, our aim is not simply to replicate all laboratory experiments in the field. In our model the laboratory phase ends with a risk hypothesis that is tested in the field in a targeted and cost-efficient manner, until it can be confirmed or rejected with a clear conscience. It is a legal requirement (explicitly stated in the Cartagena Protocol and the European Deliberate Release Directive) to study the effects on the particular environment in which the genetically modified plant is grown. We have developed a procedure whereby this can be achieved efficiently and transparently. A transparent formulation of the actual problem is a very significant and integral part of a risk analysis. It involves the detailed description of the ecosystem into which a plant is ‘released’, and all relevant interactions. You really have to do your homework carefully before you can start. |
GMO Safety: How exactly can your model be used in the safety assessment of Bt plants?
Angelika Hilbeck: We never look at the Bt plant in isolation, but always in its environment. This means that we need to draw up an inventory of relevant organisms that occur in and around the fields where the GM plants are grown. This definitely includes arthropods , i.e. insects and spiders, and other groups as well. Often we don't even know all the organisms that are found in the field. In that case we suggest an alternative approach.
First we define which functions of an ecosystem we actually want to protect and preserve. You could also call these protection goals. After all, organisms perform functions or, to put it another way, they provide us with free services, such as natural pest control by beneficial organisms, the breakdown and conversion of plant remains to humus, and pollination. As part of our GMO-ERA project, we have developed a procedure that enables us to filter out those organisms which are present in the particular ecosystem in relevant, stable numbers and perform a key function within it and, more critically, are actually exposed either directly or indirectly to the transgenic products of the GM plants, for example the Bt toxin. In other words: we ultimately concentrate on those organisms which are of ecological importance and which are significant in that any adverse impact on them by the GM plant could lead to ecological – and therefore economic – damage.
GMO Safety: To go into this in a little more detail, a type of species inventory is drawn up and then systematically reduced. How many are left in the end?
Angelika Hilbeck: That's right, a 90 to 95% reduction to around 10 to 15 species. The idea is that these species are then tested in the laboratory.
GMO Safety: Possible toxic effects on beneficial organisms are an important aspect of pesticides as well. There are recognised procedures for determining these effects prior to market approval. Do you see any parallels with the ecotoxicological testing of Bt plants?
Angelika Hilbeck: You can always learn something, even it’s how not to do it. The pesticide model does not take into account the specific environment and therefore does not meet the legal requirements of the Cartagena Protocol or other legislation, which require case-specific clarification based on the particular environment. The representative organisms selected for the pesticide model are not always ecologically significant. They are representative of specific trophic levels in individual environmental compartments, i.e. in soil or in water. For example blue algae represent primary producers, daphnia (water fleas) represent primary consumers and green lacewings represent secondary consumers. In the 60s and 70s these organisms were chosen for chemical testing because they are sensitive to the products in question, or accumulate certain substances. But they are not necessarily suitable for testing GM plants.
GMO Safety: How flexible is your model with regard to different ecosystems? The environments where Bt plants are grown can vary greatly when looked at from a global perspective. Can your model also be used for risk assessment in regions with great biological diversity?
Angelika Hilbeck: Of course. As part of our GMO-ERA project we have now conducted various case studies in Brazil, Kenya and Vietnam. With our procedure we can take into account each particular environment in a highly specific manner. This is what distinguishes our model from eco-toxicity models for pesticides, which do not allow for different ecosystems.
GMO Safety: How reliable and clear are the predictions which you are able to make about possible risks to beneficial organisms and other non‑target organisms ? What interactions do you have to be aware of and what is simply background knowledge?
Angelika Hilbeck: That varies depending on each case and is arrived at automatically using our procedure. Regional experts are an integral part of our approach because only by using them can we obtain the best possible, reliable predictions.
GMO Safety: How does your model take account of possible long-term effects?
Angelika Hilbeck: We have covered one long-term aspect by basing our model on ecological functions. The indicators, i.e. what we measure, represent many ecological functions over long-term processes. There are also practical opportunities, such as longer tests over several generations of one species and a higher number of repetitions.
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