GM Contamination Suspicion Remains Strong
Peter R Wills, University of Auckland
14 July 2002
The results and papers released by the Government do not lay to rest the suspicion that GE-contaminated corn was planted and harvested in New Zealand. If anything, they increase the suspicion.
On the day that ERMA presented its analysis of results (5 December 2000), GeneScan Australia, one of the testing companies wrote to Novartis seeds saying "Our experiences in qualitative testing leads us to believe the samples received contain trace amounts of GM sweet corn."
The probable contaminant is even identified by the testing firm: ".. one may draw the conclusion that samples received at GeneScan Australia from Novrtis Seeds do contain trace-contaminating levels of Bt11."
I would categorically contradict any scientist who said there was no suspicion of contamination on the basis of the test results. Four samples tested positive for the nos terminator which is found in BT11 and two of only three samples tested for the Cry1A construct from BT11 gave ambiguous results.
The instability of results obtained by testing for the 35S promoter has been widely discussed in the literature (see below), so failure to find this genetic construct cannot lay suspicion of contamination to rest. "Two knobs" are not required suspicion, especially when one of the "knobs" is the 35S promoter.
Scientists have a responsibility to point out uncertainties where they exist, not to present their political masters with a convenient air of authority. It would appear that the inept collusion between government, industry and scientific interests described in Hager's book is continuing
The genetic testing produced suspicion of contamination with BT11 corn, a suspicion that has never been resolved.
Just as a false positive for a tumour can only be satisfactorily resolved by finding a cyst, a false positive for GM corn can only be resolved by identifying another contaminant (like a bacterium), or by performing a proper standardised control experiment on material known to be contaminated at a specified level.
It has never been shown that the positive results from genetic testing of corn imported and sown in New Zealand were false. The further tests needed to establish clarity were not done.
[Working at the limits of sensitivity of detection (as the tests clearly were) results can be inconsistent. Detection of the 35S promoter is particularly troublesome, especially in maize. As the level of contamination decreases from 1% to 0.1% the error rate goes up from 3.5% to 16% and is expected to be worse if the level of contamination is even lower. This is the conclusion of a wide European collaboration in the field. Taiwanese workers have stated in a paper about detection of GM maize "According to our study and studies from other laboratories, an unstable result constantly occurred using the 35S-promoter primer to perform a PCR analysis on Event176 GM-maize. The reason is unclear. On the basis of this result, the 35S-promoter primer was not used for the screening test".]
Last week I lectured at the NGO "Asian Genetic Engineering Workshop" in Chiang Mai, Thailand (14 countries represented). The most two significant points of discussion at the workshop were:
1) There are no significantly new GE crops on the horizon, except for low-nicotine tobacco. Extending New Zealand's moratorium on commercial release for 5 years will have the effect only of keeping out herbicide-resistant, Bt and combination crops (in addition to the tobaaco). There are no new consumer-benefit crops or GE-foods on the horizon.
2) The US is aggressively pursuing a policy of linking acceptance of GE crop technology to economic assistance in the Asian region. New Zealand is most unlikely to be able to negotiate a free trade agreement with the US if the moratorium is extended. --
Peter R Wills
Department of Physics
University of Auckland