More inconclusive data on GM safety

October 2014

The French scientists whose long-term GM feeding experiment suggested harm to health, have voiced concerns about another study accepted by the same journal which published, then retracted, their own study [1,2]. This newly-published paper described a short-term GM feeding study carried out by a team of scientists from biotech company, DuPont Pioneer.

Food and Chemical Toxicology (FCT) withdrew the French paper last year due to the 'inconclusive' nature of some of the data (a novel ground for rejection apparently invented by the journal editors). The French team pointed out that the DuPont Pioneer study used feed compromised by an unassayed GM content which could have masked significant differences between the feeds, and ironically made the results 'inconclusive'.

The problem with the latest feeding study was that it tested GM 'Roundup Ready' canola (oilseed rape) formulated into standard rat chow so as to replace the normal soya content (about 20 percent of the total). While the added GM and control canola were tested for GM or non-GM purity and for the presence of glyphosate (active ingredient of Roundup), the final feed actually used was not. The French team pointed out that a sample of standard chow consisted of 18 percent Roundup Ready maize containing the same gene as the GM canola (in addition to 14.9 percent of a 'Bt' insectidical GM maize). It also contained 110 parts per billion glyphosate and 200 part per billion AMPA (the main metabolite of glyphosate and also a suspected toxin). Thus the study compared a 'test' diet with a 'control' which also contained elements of what was being tested.

DuPont Pioneer's main author replied that the French scientists had 'overlook(ed) that no adverse effects occurred in our study'.

Is it true that 'no adverse effects occurred'?

The male rats fed GM canola gained more weight. Male rats fed GM canola sprayed with Roundup had lower blood potassium, and male rats fed GM canola not sprayed with Roundup had higher blood calcium. Female rats fed Roundup-sprayed GM canola had reduced heart weight. Minimal heart tissue disease was observed in one-third of males fed Roundup-sprayed canola (compared with less than a tenth of near isogenic-canola fed controls).

These differences were dismissed as 'spurious', 'non-adverse', 'unrelated to diet' etc., largely by comparing the readings with data from other reference canola strains and historical data. All such comparisons are scientifically irrelevant and may also have come from data based on a standard rodent feed which included some 33 percent Roundup Ready GM maize.

Several studies have suggested endocrine disruption from Roundup and Roundup-tolerant GM feed which could alter animal and organ weight in a sex-dependent manner. Glyphosate is known to bind minerals which could alter calcium and potassium balance.

Because the DuPont Pioneer study lasted only 13 weeks and used comparisons which were both irrelevant and compromised by GM contamination, any slight differences found could well be the first indication of a problem. Put another way, a study which fed GM canola test feed for a longer time and with no background GM components muddying the results might well have produced conclusive evidence of adverse effects.

GM Watch has pointed out that although the canola study was carried out by scientists employed by the company wanting to develop the GM crop, “The authors declare that there are no conflicts of interest”. The first author of the canola paper is also managing editor of FCT, an interest which is not disclosed either.

This GM canola feeding study may be used by regulatory authorities.


Bear in mind, next time you're told how safe GM food has been proven, that this short, compromised GM canola feeding study carried out by the industry set to profit from it typifies the standard 'proof'.

[1] GM MAIZE IS NOT SAFE TO EAT - October 2012
[2] TORCHING THE SCIENCE - January 2014

  • Bryan Delaney, et al., 2014, Thirteen week rodent feeding study with processed fractions from herbicide tolerant (DP-073496-4) canola, Food and Chemical Toxicology 66
  • Robin Mesnage, et al., 2014, Letter to the Editor regarding “Delaney et al. 2014”: Uncontrolled GMOs and their associated pesticides make the conclusions unreliable, Food and Chemical Toxicology, 2.07.14
  • Bryan Delaney, 2014, Response to “Delaney et al. 2014”: Uncontrolled GMOs and their associated pesticides make the conclusions unreliable, Food and Chemical Toxicology.
  • Claire Robinson, Yhe farce of GMO industry safety studies, GM Watch 11.07.14
  • Certified Rodent Diet accessed September 2014

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