Prediction of the combined effect of various GM contamination sources of seed: A case study of oilseed rape under Danish conditions

Abstract

The potential GM contamination at each step in seed production can be predicted for conditions that correspond to a worstcase scenario. When the combined effect of the various GM contamination stages is calculated, the worst-case predictions of the different stages are normally added. This additive procedure to estimate the combined effect of GM contamination may be relevant to estimate the combined effect where a single farm is concerned, but may result in estimation errors when harvested seeds from a large number of farms are mixed. In this study, the consequences of treating the different stages of GM contamination as independent stochastic effects on the combined GM contamination have been estimated. A case study of GM contamination in organic and conventional oilseed rape crops under Danish conditions indicated that the greater part of GM contamination occurred at farm level and much less during transport and storage. Generally, it may be concluded that it is important to consider this uncertainty in the estimates of adventitious presence at each seed production step and also whether the different steps are independent.