Spatio-temporal controllability and environmental risk assessment of genetically engineered gene drive organisms from the perspective of EU GMO Regulation

Gene drive organisms are a recent development created by using methods of genetic engineering; they inherit genetic constructs that are passed on to future generations with a higher probability than with Mendelian inheritance. There are some specific challenges inherent to the environmental risk assessment (ERA) of genetically engineered (GE) gene drive organisms, since subsequent generations of these GE organisms might show effects that were not observed or intended in the former generations. Unintended effects can emerge from interaction of the gene drive construct with the heterogeneous genetic background of natural populations and/or be triggered by changing environmental conditions. This is especially relevant in case of gene drives with invasive characteristics and typically takes dozens of generations to render the desired effect. Under these circumstances, ‘next generation effects’ can substantially increase the spatial and temporal complexity associated with a high level of uncertainty in ERA. To deal with these problems, we suggest the introduction of a new additional step in the ERA of GE gene drive organisms that takes three criteria into account: the biology of the target organisms, their naturally occurring interactions with the environment (biotic and abiotic) and their intended biological characteristics introduced by genetic engineering. These three criteria are merged to form an additional step in ERA, combining specific ‘knowns’ and integrating areas of ‘known unknowns’ and uncertainties, with the aim of assessing the spatio‐temporal controllability of GE gene drive organisms. The establishment of assessing spatio‐temporal controllability can be used to define so‐called ‘cut‐off’ criteria in the risk analysis of GE gene drive organisms: if it is likely that GE gene drive organisms escape spatio‐temporal controllability, the risk assessment cannot be sufficiently reliable because it is not conclusive. Under such circumstances, the environmental release of the GE gene drive organisms would not be compatible with the precautionary principle (PP).