Risk assessment of genetically engineered plants that can persist and propagate in the environment

Abstract

New challenges arise in risk assessment when genetically engineered (GE) plants can persist and propagate in the environment as well as produce viable offspring. Next generation effects can be influenced by heterogeneous genetic backgrounds and unexpected effects can be triggered in interaction with environmental conditions. Consequently, the biological characteristics of the original events cannot be regarded as sufficient to conclude on hazards that may emerge in following generations. Potential hazards identified by the European Food Safety Authority (EFSA) include exacerbating weed problems, displacement and even extinction of native plant species. However, there are reasons for concern that might escape the environmental risk assessment (ERA) because EFSA only takes into account the characteristics of the original events, leaving aside unintended or unexpected next generation effects emerging from spontaneous propagation and gene flow. From our review of the publications available and the analysis of risk assessment as performed, we conclude that the risk assessment of GE organisms able to persist and spontaneously propagate in the environment actually suffers from a high degree of spatio-temporal complexity causing many uncertainties. To deal with this problem, we recommend establishing ‘cut-off criteria’ in risk assessment that include factual limits of knowledge. It is proposed that these criteria are applied in a specific step within risk assessment, i.e. ‘spatio-temporal controllability’ that uses well-defined biological characteristics to delineate some of the boundaries between known and unknowns. This additional step in risk assessment will foster robustness in the process and can substantially benefit the reliability and overall conclusiveness of risk assessment and decision-making on potential releases.