Industry may be holding proof of contamination
Evidence still being withheld. Industry may be holding proof of contamination.
Peter R Wills, BSc, PhD
16 July 2002
Evidence that corn grown in New Zealand was potentially GE-contaminated is still being kept from the public.
The evidence being withheld concerns the results of tests conducted by GeneScan Australia on samples of Lot NC9114 (Novartis) sweet corn. There are two sorts of evidence still being withheld.
1. The government has not released reports (received from GeneScan by 5 December 2000) of any of the qualitative tests that proved positive for GE contamination of Novartis corn seed. The government has released the reports of negative results only.
2. The government has not produced the results of further testing that GeneScan said it had not finished by 5 December 2000. [The GeneScan letter of 5 December, but not received by ERMA until the next day, suggests that further tests were being conducted by using the much more sophisticated "Quantification by Online-PCR" method advertised by GeneScan. Only the results of qualitative testing to a specified level of detection, returning a "+" or "-" for each pair of duplicate samples, were available on 5 December 2000.]
Two of the positive (qualitative) results reported by ERMA on 5 December 2000 cannot be interpreted as the result of bacterial contamination. The results from GeneScan show that 2 out of only 3 samples tested returned an unduplicated positive for a genetically engineered sequence specific to Novartis BT11 corn, the ADH-Cry1A(b) construct. If these positive tests are to be conclusively dismissed as methodological (PCR) artefacts this would have to be demonstrated by sequencing of the PCR product or, less desirably, by showing the occurrence of artefacts (false positives) in guaranteed uncontaminated samples (when the same standardised protocols are followed).
In the absence of the required evidence, there is no proper scientific basis for categorical claims (such as those emanating from the Prime Minister and Minister for the Environment) that corn from Lot NC9114 was not contaminated with genetically engineered BT11 kernels. The unduplicated positive results for the ADH-Cry1A(b) construct constitute prima facie evidence of contamination that requires proper investigation and resolution. The scientific evidence raises the possibility of contamination close to the level of detectability, a possibility that was not properly investigated by the available reasonable means.
The GeneScan letter of 5 December 2000 refers to experiments that were still in progress to make quantitative measurements of the level of the 35S promoter gene, but which could not be completed at that time because of machine malfunction. [I interpret the reference to machine malfunction, as well as the reference to "quantitation", in terms of experiments using the sophisticated Online-PCR method in which the sample is usually observed fluorimetrically while the reaction takes place. I cannot imagine that all of GeneScan's ordinary PCR machines had broken down.] The letter states that "early test results indicate that quantitation of the 35S promoter .. will be at a level lower than 1/5000" but reinforces the conclusion that "samples received at GeneScan Australia from Novartis Seeds do contain trace-contminating levels of Bt11".
The following important questions remain:
1. Did GeneScan find positive proof of GE contamination in Lot NC9114 after 5 December by completing measurements made by using the more sophisticated Online-PCR method?
2. Were any results of such tests supplied to Novartis?
3. Did Novartis, who had originally alerted the government that its seed might be contaminated, sit on results obtained after 5 December, confident that the New Zealand government had by then decided to allow the planting and harvesting in New Zealand of a crop now proved to be GE-contaminated?
When all of the evidence has been released it may be possible to put the matter to rest.
[Note: The differences between the results produced by GeneScan and Crop and Food can be explained in terms of GeneScan being better (more sensitive detection) than C&F or worse (more artefacts). I do not have any evidence on which to judge the matter and I am suspicious of the judgment of an interested party. Much of the dispute about the interpretation of test results comes from Russell Poulter who I am told has some connection with Crop and Food. He dismisses the GeneScan assessments in favour of a declaration from C&F that the positively testing samples were actually GE-free. I suspect that PCR-envy is playing a role here and that rivalry for technical prowess has sullied objective analysis. ] --
Peter R Wills
Department of Physics University of Auckland