As is the case with many other risks, it is the overall environmental exposure and not just the quality of the individual factors that can be decisive for potential damage. We are warning that the large-scale release of many different genetically engineered organisms into the environment within a short period of time, might cause a possible collapse of ecosystems that could not be predicted by the current system of risk assessment. Therefore, the impact of the technology has to be taken into account in its entirety. Prospective technology assessment (TA) can play an important role in this context. TA enables detailed examination of the claimed potential benefits of ‘gene scissors’ applications in breeding and agriculture. Currently, only the risks associated with the individual organisms are assessed within the regulatory approval process. However, if the environment is exposed to a large number of different genetically engineered organisms possibly belonging to several species, the overall risk of ecosystem collapse may very much depend on the scale of their release. In this context, reliable instruments and criteria are needed to distinguish traits with ‘real benefits’ from those which are just ‘empty’ or ‘false’ promises. There should also be further consideration of possible adverse effects on socio-economic systems, such as food production and the breeding of plants and animals. While TA cannot replace the risk assessment of the individual organisms (events), it can nevertheless help political decision-making in seeking a balance between potential benefits and the need to reduce the overall risk of adverse effects on biodiversity and planetary health.