NK603 maize is not equivalent

January 2017
Photo: Creative Commons

It has long been a refrain in GM-free Scotland articles that the 'safety testing' of GM foods is too crude, too limited and too old-fashioned to tell us anything except that eating it won't make anyone drop dead. Science has many more sophisticated and more meaningful testing techniques at its disposal, if only there was the will to develop them for routine use.

At the end of 2016, however, the ball finally got rolling.
The first analysis of a GM crop based on cutting-edge molecular profiling has been published, and the results give cause for concern.

An international team of scientists carried out detailed analyses of the proteins and small biochemicals generated during cellular processes in the kernels of a GM maize.

The maize was 'NK603' which is tolerant to glyphosate herbicide. It was the same maize which was fed to rats in a whole-life experiment that the biotech industry would prefer hadn't been done [1]: it indicated a risk of liver and kidney disease, and tumours.

Molecular profiling of NK603 showed a total of 117 proteins and 91 small biochemicals were significantly altered by the genetic transformation. There was impairment of energy-producing processes and increased cell-damaging stress markers.

Glyphosate-tolerant maize, at least of this strain, appears intrinsically stressed and to have compromised resources to deal with further environmental stresses.

Also of note was an increase in 'polyamines', a class of small molecules derived from protein components, which are tightly regulated in the cell. Polyamines are involved in many cell processes, for example gene expression and regulation, cell growth, nerve cell health, and stress resistance. Some polyamines can become toxic at raised levels or in the wrong context putting the organs of detoxification, the liver and kidney, at long-term risk of disease. At least two of the polyamines found to be raised have been implicated in potentiating allergic reactions and in the formation of carcinogenic substances in meat products.

Some unexpected results emerged from the study. One was that no changes were detected in the 'shikamate' biochemical pathway. The shikamate pathway is vital in the manufacture of specific essential building blocks of protein. Glyphosate is supposed to kill weeds by blocking this pathway, and the genetic modification in glyphosate-tolerant plants is designed to by-pass glyphosate's block. Yet, there were no signs in either sprayed nor unsprayed NK603 that anything was altering the shikamate pathway.

Our understanding of what glyphosate or our artificial genes are actually doing in the plant, as opposed to the scientific theory of what we think they're doing, seems to be deficient.
The sprayed NK603 plants were treated once with glyphosate early in the season before the cobs formed. Despite the possibility of glyphosate accumulation in GM herbicide-tolerant plants, no glyphosate was detected in the kernels. However, the sprayed test plants had significant molecular profile differences from the unsprayed ones grown nearby. This indicated that, surprisingly, the herbicide induced permanent changes in gene expression of the whole plant. It's possible that changes of this type could be passed on to the next generation.

It was pointed out by the authors that approval for marketing of GM crops is based on the 'substantial equivalence' of their nutrient composition (except for the intentional protein changes).
'Substantial equivalence', however, has no clear definition. The concept is a "basis for comparison" (OECD): it "does not imply absolute safety of the new product; rather, it focuses on assessing the safety of any identified differences so that the safety of the new product can be considered relative to its conventional counterpart" (Codex). It's clear that the concept of substantial equivalence should not be used as a proof of safety. The authors conclude from their findings that NK603 GM maize has "hampered nutritional quality" and is "markedly different" from its parent non-GM form: the two "are not substantially equivalent".

The study also highlights the importance of restricting GM/non-GM comparisons to crops with identical genetic backgrounds and grown under identical environment conditions. Without this, the crops will be intrinsically non-substantially equivalent due to environmental interactions.
Industry tricks, such as refusing to make suitable GM/non-GM test material available for testing, declaring differences 'not biologically significant' , or flooding the data with irrelevant incomparable comparators, must be outlawed.

Molecular profiling of another commercialised GM crop, MON810 Bt insecticidal maize, also revealed disturbances in energy pathways, genetic information processing and stress response. Newer GM maize crops are coming stacked with multiple Bt genes plus herbicide-tolerance traits. At what point will the balance tip towards an unviable crop? 

Now that we have the technology to identify unpredicted changes in the composition of a GM food, there's no reason not to use it, and every reason to check out the safety of all commercialised GMOs again. Ask you MEPs to see it's done.

[1]  GM MAIZE IS NOT SAFE TO EAT - October 2012

  • Robin Mesnage, et al., 2016, An integrated multi-omics analysis of the NK603 Roundup-tolerant GM maize reveals metabolism disturbances caused by the transformation process, Nature Scientific Reports, 19.12.16
  • Leonor Miller-Fleming, et al., 2015, Remaining Mysteries of Molecular Biology: The Role of Polyamines in the Cell, Journal of Molecular Biology 427 
  • GMO maize NK603 is not substantially equivalent to its non-GMO counterpart, GM Watch 19.12.16 

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