Analysis of the Prevalence of CDC Triffid Transgenic Flax in Canadian Grain Stocks

CDC Triffid transgenic flax was deregistered in 2001 due to concerns about the effect of its production on offshore markets. A decade after removal of CDC Triffid from the commercial system in Canada, it was detected in grain shipments to Europe. This event resulted in a disruption of trade between Canada and the EU. To demonstrate compliance, the industry in Canada adopted a testing protocol involving testing grain samples (post-harvest) using a RT-PCR test for the construct found in CDC Triffid. This study re-evaluates GM presence in Canadian grain stocks for the updated data set of 2009-2013 using a previously described simulation model to estimate low-level GM presence. The test results were broken down by category (i.e., seed or grain) as well as crop year. For each category of seed or grain, it was determined whether the observed positives deviated from the expected number of false positives (i.e., due to chance alone). In most cases, the number of positive tests was significantly higher than expected due to chance alone. For these categories of seed or grain, a simulation model was applied to the test results to estimate GM contamination levels. The number of positive tests showed a downward trend, indicating removal of transgenic flax from the commercial system. However, low-level GM presence persists in grain stocks. A way forward for the Canadian grain industry is presented, including renewal of seed stocks with reconstituted GM-free varieties