Risk assessment for Bt plants: two concepts
Before a Bt plant is released, and especially before it is authorised
for commercial cultivation, tests have to be carried out to check that
this will not be associated with any harmful impacts on non-target
organisms. The authorisation decision is not always easy for the
authorities responsible. On the one hand, they have to reach a result
within a reasonable amount of time, while on the other they have to take
into account complex ecological relationships.
The first genetically modified Bt maize variety was authorised in the
USA over ten years ago. Now Bt maize and Bt cotton are grown on more
than twenty million hectares worldwide, and the area under cultivation
is expanding. With other plant species too, scientists are looking at
ways of using the Bt concept to control harmful grazing insects. But
again and again there are discussions about whether the Bt toxin
produced in the plant has an effect on other organisms as well as the
pest it is designed to control.
In different cultivation regions, different non-target organisms come
into contact with the Bt plants and the Bt toxin they produce. Do we
need separate research for each crop and the non-target organisms that
might be affected by it? Or is it possible to develop suitable standard
tests that can be applied effectively and that still deliver
comprehensive, reliable results? In the field of biological safety
research, this discussion has already begun.
GMO Safety spoke to Angelika Hilbeck and Jorg Romeis. These two
scientists work in Switzerland. They represent international working
groups dealing with the development of suitable models for the
ecological risk assessment of Bt maize on non-target organisms.
Standard tests with representative organisms: Jorg Romeis’s
international working group is proposing a step-by-step process. It is
based on a sequence of laboratory, semi-field and field experiments. The
approach follows the globally established methods for environmental
testing of toxic substances and pesticides.
The focus of the research is on standardised tests in the laboratory
with various ‘representative organisms’ selected according to a range of
criteria. In the laboratory, toxic effects can be identified in a
targeted manner and with a high level of statistical confirmation. If
the lab tests provide indications of harmful effects, more
investigations are carried out and, if necessary, field trials as well.
With this approach it is possible to reduce the need for expensive field
trials. In some cases they can be avoided altogether.
Interview with Jorg Romeis: "We conduct targeted tests on representative
organisms".? (interview can be downloaded from below)
Studying the most important organisms in an ecosystem: Angelika
Hilbeck’s international working group is advocating a much broader
approach. It believes the existing ecotoxicological test methods are
inadequate, especially for regions with high biodiversity. In her
opinion, the standardised approach with selected ‘representatives’ in
the laboratory does not provide enough information to be able to make
assertions about effects on biodiversity in the ecosystem. Before a test
is conducted in the laboratory, the most important non-target organisms
with key ecological functions for the ecosystem in question need to be
identified. Laboratory tests are then carried out on these organisms and
supplemented by field trials.
Interview with Angelika Hilbeck: "We filter out 10 to 15 species which
we then examine in more detail."? (click here)