Aspects of the biosafety of transgenic oilseed rape (Brassica napus L.)

Genetic modification of crop plants has resulted in plants resistant against pathogens or showing improved quality. Within the coming years it is expected that more transgenic crops will be commercialized and there is little doubt that transgenic plants will significantly contribute to agriculture in the future (Dale & Irwin 1995). Calgene’s Laurate oilseed rape has now full clearance from the US authorities for commercialization (APHIS/USDA 1994). However, developments in the patenting of genes, the release regulations, food labelling and consumer attitude will influence the implementation rate. Genetically modified or transgenic plants are defined according to Stiekema & van Vloten-Doting (1991) as plants which genomes accommodate new pieces of DNA which are introduced by other procedures than sexual crossing. In spite of the fact that close similarities exist between the phenotypes of transgenic and non-transgenic crops, its application cannot simply be equalled to traditional breeding. Genetic modification makes possible the circumvention of the natural crossing-barriers between species established by evolutionary processes. Unforeseen consequences (see, for example, Maessen, 1997, this issue) may be the result and, therefore, prior to the release of these transgenic crops, their biosafety has to be assessed (Kapteijns 1993). This includes the assessment of aspects such as gene dispersal and introgression of these genes in their wild relatives via, subsequently, greenhouse experiments, small-scale field experiments followed by large-scale field trials (see, for example, Van Raamsdonk & Schouten, 1997, this issue). In this respect the Dutch government follows a ‘case by case’ and ‘step by step’ policy on the release of genetically modified transgenic plants into the environment. As starting point the ‘yes, provided that ...’ principle is handled, which means that it is allowed to produce and grow genetically modified plants, provided no additional ecological and toxicological negative side effects occur. The OECD ‘familiarity principle’ (OECD 1993a)—biotechnology is acceptable if no additional negative aspects are involved compared to conventional methods—and the criterion of ‘substantial equivalence’ (OECD 1993b)—transgenic food is acceptable as long as it meets already accepted threshold values for toxic components—express the same policy in an international context.