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					       ISB NEWS REPORT                                                                      FEBRUARY 2003

                          GENE FLOW FROM GM TO NON-GM
                                                     John Ruane

This document presents an abbreviated summary of discussions in the FAO e-mail conference, which took
place from May 31 to July 6, 2002. During the moderated conference, discussions focused overwhelmingly on
the issues concerning gene flow in the crop sector with only a few messages dedicated solely to these issues in
forest trees, fish, or animals. From the discussions it was clear that widely differing opinions are held regarding
genetically modified organisms (GMOs) and the current or potential impacts of gene flow.

The main topic of discussion in the conference was the real or potential ecological impacts of gene flow and, in
addition, how a science-based ecological risk assessment framework might be applied to gene flow.

Regarding the ecological impacts, discussions focused on two main areas. The first was the impacts of gene
flow on biodiversity. Here, it was argued that transgene flow might have greatest impact on the within-species
genetic diversity of domesticated populations and, secondly, that other factors (such as the introduction of
invasive alien species) could have far greater impacts on biodiversity. These other negative factors were either
seen as putting gene flow in perspective as a minor problem or, alternatively, they encouraged participants to
call for prudence as, initially, people had often not considered their potential risks. The second area was the
ecological impacts of specific trans-genes—either those currently in use, affecting herbicide tolerance and
insect resistance traits, where it was argued that spread of these transgenes to non-target plants could have or
already had negative ecological impacts (the case of herbicide tolerant GM canola in Canada was mentioned in
particular), or transgenes that might be used in the future. Because different transgenes may raise different
ecological issues in different environments, it was proposed that the ecological impacts of gene flow should be
considered on a case-by-case basis rather than as a whole.

Assessing the ecological risk of gene flow was considered by participants to be very important prior to GMO
release. In this context, there was much detailed discussion about two key terms that need to be considered in
an ecological risk assessment framework, i.e., hazard (undesired/injurious events or harm caused by gene flow
to the environment) and exposure (the frequency of gene flow or the probability of the transgene spreading in
the environment). The problems of identifying the hazards and testing for them were raised, as well as the
complexities involved in predicting exposure. Participants were generally positive about using population
genetics mathematical models for predicting the spread of transgenes in the wild.

A number of messages dealt with specific aspects of ecological risk assessment in developing countries. Here,
the lack of key information on the ecology of native plant species was a common theme and the need to gener-
ate this information to enable risk assessment to be carried out using local ecological information was empha-
sized. It was also argued that the assessment needs to be based on the realities of local farming systems in
developing countries, where farm sizes may be small and mixing of varieties and seed-saving may be common

Several participants emphasized the importance, after carrying out an ecological risk assessment of gene flow
from a GM variety, of weighing the risks in a bigger context, i.e., against the gene flow risks associated with
conventional breeding practices; considering the environment in which the GM varieties might be used (e.g.,
whether suffering environmental degradation); and, thirdly, against the potential benefits of the GM variety.

Three other topics that generated a good deal of discussion were i) whether GMOs are fundamentally different
from conventionally bred organisms (CBOs), thus entailing new gene flow hazards, ii) strategies to limit gene
flow, and iii) economic impacts of gene flow.

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       ISB NEWS REPORT                                                                             FEBRUARY 2003

There was no consensus on the first of these topics, which was highly contentious, resulting from a dichotomy
in the way that GMOs are viewed in relation to CBOs. For participants who considered that GMOs do not
differ fundamentally in their genetic make-up from CBOs, gene flow from GM-populations was not more of an
issue than gene flow from non-GM populations. For those, on the other hand, who considered them to be
fundamentally different, it was important that the unique features of GMOs be identified and the consequences
of their dispersal by gene flow be evaluated. The two main unique features proposed in this context were that
GMOs may transfer exotic/foreign genes (of other species) to individuals of the same population, to wild
relatives or to different species, with potential evolutionary implications, and, secondly, that the genetic modifi-
cation process may create organisms that are potentially unstable, due to the way transgenes are regulated and
since transgene insertion could damage the host DNA.

For the second topic, given the concerns about the ecological impacts of gene flow, as well as the potential
difficulties involved in assessing its ecological risk (due to problems in identifying potential hazards and
predicting exposure), an alternative approach proposed was to simply prevent or limit gene flow from GM
populations. This seemed to receive general support from all parts. The pros and cons of a range of different
strategies were discussed, including temporal or spatial separation of GM and non-GM populations, ensuring
that GMOs (or the pollen) are sterile, or chloroplast genetic engineering (where the transgene(s) is inserted into
the chloroplast genome rather than the nuclear genome). It was also suggested that these strategies might be

The third of these topics dealt with two main aspects concerning the economic impacts of gene flow: the
potential negative implications for trade and export to non-GMO markets if gene flow occurs (mentioned as
being especially detrimental for developing countries) and, secondly, the impacts of intellectual property issues,
as ownership of genes or seeds raises the question of liability if gene flow causes damage and, secondly, patent
owners may decide to enforce intellectual property legislation if gene flow takes place.

Finally, three other topics were given minor attention in discussions. The first was a reminder that, apart from
the ecological and economic impacts, there is also a philosophical/ethical dimension to the gene flow question.
The potential importance of this aspect for indigenous peoples was mentioned. The second was gene flow in
centers of origin and diversification, where participants emphasized that the topic requires special attention
because of the complex mixture of scientific, social, and cultural issues that it raises. The third was gene flow
to organic agriculture, which is an especially sensitive issue as organic agriculture does not permit use of
GMOs. The specific case of organic canola farming in Canada was discussed.

A more detailed summary, including references to specific e-mail messages, has been published and is available
at The individual e-mail messages can be read at http://

                                                                                                              John Ruane
                                                                                    FAO Working Group on Biotechnology
                                                                    Food and Agriculture Organization of the UN, Rome, IT

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