Five times removed from natural

December 2017
© Greenpeace / Statchett
A huge focus of GM development has been on crops which can generate their own insecticides against key pests. Such crops have added genes copied from the, seemingly ubiquitous, soil bacterium, Bacillus thuringiensis ('Bt') which enable the plants to produce 'Bt' toxic proteins targeting specific insects.

'Bt' crops are promoted by industry and regulators as environmentally-friendly, farmer-friendly and consumer-friendly. After all, they target specific pests only, they breakdown quickly in the soil, they are designed to reduce the need for expensive chemical insecticide applications in the field and on our food. B. thuringiensis is a "naturally occurring" bacterium, producing natural protein toxins which will be naturally digested in the human gut and are, therefore, naturally safe to eat. Moreover, so the story goes, approved commercial Bt preparations have been "extensively" and safely used for "over half a century" in organic farming and in forestry, decades before the GM crop era.

This 'naturalness' and 'history of safe use' have been used by industry and regulators to justify the minimisation of actual testing.

There's another version of this tale if you look at the pedigree of that Bt gene in your food-chain. It's great-great-great-grandmother is a common, naturally-occuring bacterium. The gene is reborn in a test-tube minus all the rest of that common, naturally occurring bacterium it used to live in. Its great grandmother is another species of bacterium altogether (some common laboratory strain). After this, the gene goes back into a test tube prior to rebirth in it mother, a plant cell. Once the gene actually becomes part of the plant genome (five 'generations' removed from the natural Bt), it is subject to multiple cross-breeding with plants of the same species to achieve the final crop with the desired genetic characteristics.

There are a series of surrogate 'mothers' here, each stage of which involves planned or unplanned changes to that original 'natural' Bt DNA. Some of these changes are deliberate and necessary to enable DNA processing in a test-tube and DNA reproduction in a foreign organism. Many of the changes are the unintended, but inevitable, outcome of the sequence of artificial manipulations it has undergone.

Independent scientists have been questioning how genes with such a chequered history could be assumed to arrive on our plates so unscathed that they barely need tested. Accordingly, they undertook a review of 23 globally traded crops containing Bt gene 'events'. They analysed the documents submitted by industry for commercial approval, along with the patents filed by industry to prove their genes are unique inventions (despite their 'naturalness' naturally). Some disturbing facts emerged from this.

There were six chemical differences between specific 'Bt' proteins found in B. thuringiensis and the analogous GM 'Bt' protein found in GM Bt plants. All the GM crops had some of these differences, and some of the GM crops had all of them. Each type of change introduced uncertainties in the properties of the protein which would increase the toxicity of that protein. The changes were:

  1. All natural Bt proteins exist in an inert, insoluble crystalline form which must be denatured to release its toxic potential; all GM Bt proteins come already soluble and ready to kill. 
  2. GM Bt proteins are typically almost half the size (in terms of the number of amino-acid building blocks) of their natural counterpart. Even the Bt event in MON810 maize stated by Monsanto to be "identical to that present in nature" appears to be only some 70% of the size of the protein its supposed to be identical to. The missing segments are the bits which control toxicity to prevent spurious environmental harm. 
  3. Totally novel hybrid toxins created by combining parts of different Bt proteins specifically to increase toxicity aren't unusual. 
  4. Totally novel toxins with added unrelated proteins or synthetic constructs specifically to increase toxicity aren't unusual.
  5. Deliberate mutations to replace individual protein building blocks (amino-acids) specifically to increase toxicity aren't unusual. 
  6. Lastly, "and far from least" is that all the GM Bt proteins produced by GM Bt plants have not only been carefully selected from hundreds or thousands of 'sibling' GM plants for their exceptional toxic action, but had been additionally altered inside the plant cells by the plant itself . All of them were consistently more toxic than the wild-type form. 
The second question explored by the independent scientists was whether these six sources of chemical change enhanced GM Bt protein toxicity with real-world implications for food safety and biosafety. Their answer was, unequivocally, 'yes'.

Indeed, industry measurements of how toxicologically active their GM Bt proteins were once inside the plants showed increases of up to 10-fold. Monsanto has patented a series of novel Bt toxins with up to 7.9-fold enhanced activity and proudly refers to them as "super toxins" having "the combined advantages of increased insecticidal activity and concomitant broad spectrum activity". New GM crops on the market contain as many as six Bt toxins: that's a vast quantity of enhanced, and possibly cumulative killing power. It seems that the environmentally-friendly aspect of Bt crops has gone out the window.

And, are Bt super-toxins safe for us to eat?

The minimal testing that has been done has used the version of the toxin produced by that great grandmother, the one that's unrelated to either B. thuringiensis or to any crop plant. So, the simple answer is who knows?

Add to this that there's plenty of evidence of multiple extra unintended novel proteins in Bt plants. These are typically dismissed, without any supporting science, as artefacts of processing, impurities, degradation products, or (if they're big) aggregates of what should be there anyway.

While industry and regulators concentrate on verifying the qualities of the expected Bt protein, the potentially harmful, unexpected, novel proteins generated alongside it in the plant are rendered invisible. It's been shown that at the least one commercialised Bt protein can circulate in the human and foetal bloodstream, and can survive in the digestive systems of pigs; the fate of all those unexpected novel proteins is anyone's guess.


If you're getting the impression that Bt insecticidal crops haven't actually had any safety testing at all, and that "regulators" have been carefully groomed by industry to swallow whatever scientifically unsupportable assumptions are needed to keep GM crops on track, you might be right.

There's huge array of toxins produced by B. thuringiensis and other soil bugs which are set to be recreated in an infinity of (untested) forms and popped into your food.

The paper describing the routine lack of science in insect-resistant crop approval is open access and can be forwarded to your MP, MEP and MSP ( Add a polite request for the implementation of the improved science-based risk assessment recommendations described in the article.

The paper is:

Jonathan Latham, Madeleine Love, and Angelika Hilbeck, 2017, The distinct properties of natural and GM cry insecticidal proteins, Biotechnology and Genetic Engineering Reviews


  • Mohamed A. Ibrahim, et al., 2010, Bacillus thuringiensis - A genomics and proteomics perspective, Bioengineered Bugs, US National Library of Medicine
  • Jonathan Latham, Have Monsanto and the Biotech Industry Turned Natural Bt Pesticides into GMO "Super toxins" 2017
  • Are GMO Pesticides Supertoxins? A New Analysis Raises Questions of Food and Environmental Safety, The Bioscience Resource Project Press Release, 4.10.17

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