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Spatially isolating genetically modified (GM) maize fields from non-GM maize
fields is a robust on-farm measure to keep the adventitious presence of GM
material in the harvest of neighboring fields due to cross-fertilizations
below the European labeling threshold of 0.9%. However, the
implementation of mandatory and rigid isolation perimeters can affect the
farmers' freedom of choice to grow GM maize on their fields if neighboring
farmers do not concur with their respective cropping intentions and crop
plans. To minimize the presence of non-GM maize within isolation perimeters
implemented around GM maize fields, a method was developed for optimally
allocating GM maize to a particular set of fields. Using a Geographic
Information System dataset and Monte Carlo analyses, three scenarios were
tested in a maize cultivation area with a low maize share in Flanders
(Belgium). It was assumed that some farmers would act in collaboration by
sharing the allocation of all their arable land for the cultivation of GM
maize. From the large number of possible allocations of GM maize to any
field of the shared pool of arable land, the best field combinations were
selected. Compared to a random allocation of GM maize, the best field
combinations made it possible to reduce spatial co-existence problems, since
at least two times less non-GM maize fields and their corresponding farmers
occurred within the implemented isolation perimeters. In the selected field
sets, the mean field size was always larger than the mean field size of the
common pool of arable land. These preliminary data confirm that the optimal
allocation of GM maize over the landscape might theoretically be a valuable
option to facilitate the implementation of rigid isolation perimeters
imposed by law.
Recapitulating how genetic modification technology and its agro-food
products aroused strong societal opposition in the European Union, this
paper demonstrates how this opposition contributed to shape the European
regulatory frame on GM crops. More specifically, it describes how this
opposition contributed to a de facto moratorium on the commercialization of new GM
crop events in the end of the nineties. From this period onwards, the
regulatory frame has been continuously revised in order to slow down further
erosion of public and market confidence. Various scientific and technical
reforms were made to meet societal concerns relating to the safety of GM
crops. In this context, the precautionary principle, environmental
post-market monitoring and traceability were adopted as ways to cope with
scientific uncertainties. Labeling, traceability, co-existence and public
information were installed in an attempt to meet the general public request
for more information about GM agro-food products, and the specific demand to
respect the consumers' and farmers' freedom of choice. Despite these
efforts, today, the explicit role of public participation and/or ethical
consultation during authorization procedures is at best minimal. Moreover,
no legal room was created to progress to an integral sustainability
evaluation during market procedures. It remains to be seen whether the
recent policy shift towards greater transparency about value judgments,
plural viewpoints and scientific uncertainties will be one step forward in
integrating ethical concerns more explicitly in risk analysis. As such, the
regulatory frame stands open for further interpretation, reflecting in
various degrees a continued interplay with societal concerns relating to GM
agro-food products. In this regard, both societal concerns and diversely
interpreted regulatory criteria can be inferred as signaling a request –
and even a quest – to render more explicit the broader-than-scientific
dimension of the actual risk analysis.
The ongoing discussion on the co-existence between genetically modified (GM) and non-GM crops becomes more important in the European Union (EU). With the recent inscription of 17 GM maize varieties in the common EU catalogue of varieties of agricultural plant species, the acreage of transgenic maize for market purposes is expected to increase in some European countries. In the EU, specific tolerance thresholds have been established for the adventitious and technically unavoidable presence of GM material in non-GM produce, and member states are elaborating legal frames to cope with co-existence. As maize is a cross-pollinated crop relying on wind for the dispersal of its pollen, technical management measures will be imposed to reduce cross-fertilization between transgenic and non-transgenic maize. Various biological, physical and analytical parameters have been identified to play a role in the study of cross-fertilization in maize. This variability may hamper the comparison between research results and may complicate the definition of appropriate isolation distances and/or pollen barriers in order to limit out-crossing. The present review addresses these parameters and proposes containment measures in order to not exceed the legal labeling thresholds in maize.
The potential commercialization of genetically modified herbicide-tolerant (GMHT) oilseed rape in Europe raises various concerns about their potential environmental and agronomic impacts, especially those associated with the escape of transgenes. Pollen of oilseed rape can be dispersed in space, resulting in the fertilization of sympatric compatible wild relatives (e.g. Brassica rapa) and oilseed rape cultivars grown nearby (GM and/or non-GM Brassica napus). The spatial and temporal dispersal of seeds of oilseed rape may lead to feral oilseed rape populations outside the cropped areas and oilseed rape volunteers in subsequent crops in the rotation. The incorporation of a HT trait(s) may increase the fitness of the recipient plants, making them more abundant and persistent, and may result in weeds that are difficult to control by the herbicide(s) to which they are tolerant. Vertical gene flow from transgenic oilseed rape to non-GM counterparts may also have an impact on farming and supply chain management, depending on labelling thresholds for the adventitious presence of GM material in non-GM products. Given the extent of pollen and seed dispersal in oilseed rape, it is obvious that the safe and sound integration of GMHT oilseed rape in Europe may require significant on-farm and off-farm management efforts. Crucial practical measures that can reduce vertical gene flow include (1) isolating seed production of Brassica napus, (2) the use of certified seed, (3) isolating fields of GM oilseed rape, (4) harvesting at the correct crop development stage with properly adjusted combine settings, (5) ensuring maximum germination of shed seeds after harvest, (6) controlling volunteers in subsequent crops, and (7) keeping on-farm records. The implementation of the recommended practices may, however, be difficult, entailing various challenges.
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