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In 1990, Monsanto scientists published their latest discovery about the new 'Bt' insecticides generated by GM crops which were soon to become every farmers 'must-have'.
Their exciting finding, with an "immediate commercial implication" was that the insecticidal power of Bt could be increased many fold if its degradation was prevented by the plant itself. Many plants produce substances which prevent the breakdown of proteins, such as the Bt toxin, possibly to keep herbivores at bay by interfering with their digestion. The authors suggested this would confer "significant and long-term implications and benefits" on Monsanto's "genetically improved" Bt-generating plants.
Safety assessment of the new Bt crops was based on two strands of evidence.
One was that organic farmers have been spraying Bacillus thuringiensis, the soil bacteria which naturally produce 'Bt' insecticide, onto their crops for years with no ill-effects.
The second was based on feeding studies. These tested how toxic the Bt protein was for selected insect pests, and how non-toxic it was in food or feed. Such studies used purified bacterium-derived Bt protein. As safety assessments such studies have short-comings: they don't test what we (or our livestock) will actually be eating in a GM plant diet.
When sprayed onto a crop, the natural Bt in the bacteria is first exposed to sun-light which will begin its degradation, and then to protein-digesting enzymes in the environment which will complete the destruction. In other words, the Bt toxin is active for a short time and quickly disappears.
In real-life modern agriculture, however, GM plants can generate the Bt protein along with natural substances which prevent its degradation: the Bt toxin will take a long-time to disappear.
This means that GM Bt protein may have its insecticidal power increased many fold because more of it hangs around for a longer time. It also means that any toxic and allergenic effects will be multiplied in people and in the environment.
Fast-forward three decades. The safety assessment of Bt crops hasn't become any more sophisticated. And, the persistently higher concentrations of undegraded Bt protein in food and the environment will now be boosted by the latest GM crops which are increasingly stacked with multiple kinds of Bt toxin.
In 2019, Nigeria approved the cultivation of Bt cowpeas.
Cowpea is one of the most ancient crops, domesticated more than 1,500 years ago in Africa, near Ethiopia. It has become a significant part of pan-African heritage, now grown extensively throughout sub-Saharan Africa, and consumed by some two hundred million Africans.
While Africa remains the largest cowpea production area, the crop is also grown in Brazil, west India, Myanmar, Sri Lanka, Australia and the USA. Bt cowpeas could be very big business for their suppliers.
Cowpeas naturally produce substances which inhibit protein degradation, suggesting any adverse effects of the novel Bt are very likely to be significantly enhanced.
Increased Bt toxicity and immunogenicity are serious concerns for human safety because cowpeas are so widely consumed. Moreover, in a country where so many farmers grow cowpeas, and a collection of over 15,000 landraces of cowpea is maintained, contamination from Bt gene flow into non-GM crops, including the unique gene-bank, could have serious consequences for an invaluable and irreplaceable resource.
Domesticated cowpeas have over 2000 wild relatives in Africa. Although there are barriers to hybridisation between domestic and wild plants, these are far from complete. Bt gene flow into weeds, which might well have their own substances that prevent degradation of the GM protein, is potentially disruptive to ecosystems well beyond the fields.
We desperately need long-term feeding and environmental studies using up-to-date toxicological analytical methods and the Bt plants we're actually eating, especially those GM (not 'genetically improved') crops with multiple, stacked varieties of Bt-toxin.
Westminster's gung-ho attitude to GMOs could soon flood our bodies and environment with a whole host of GM proteins whose toxicity has never been recognised. Prepare to demand proof not assumptions that Bt plants are safe.
SOURCES
The second was based on feeding studies. These tested how toxic the Bt protein was for selected insect pests, and how non-toxic it was in food or feed. Such studies used purified bacterium-derived Bt protein. As safety assessments such studies have short-comings: they don't test what we (or our livestock) will actually be eating in a GM plant diet.
When sprayed onto a crop, the natural Bt in the bacteria is first exposed to sun-light which will begin its degradation, and then to protein-digesting enzymes in the environment which will complete the destruction. In other words, the Bt toxin is active for a short time and quickly disappears.
In real-life modern agriculture, however, GM plants can generate the Bt protein along with natural substances which prevent its degradation: the Bt toxin will take a long-time to disappear.
This means that GM Bt protein may have its insecticidal power increased many fold because more of it hangs around for a longer time. It also means that any toxic and allergenic effects will be multiplied in people and in the environment.
Fast-forward three decades. The safety assessment of Bt crops hasn't become any more sophisticated. And, the persistently higher concentrations of undegraded Bt protein in food and the environment will now be boosted by the latest GM crops which are increasingly stacked with multiple kinds of Bt toxin.
In 2019, Nigeria approved the cultivation of Bt cowpeas.
Cowpea is one of the most ancient crops, domesticated more than 1,500 years ago in Africa, near Ethiopia. It has become a significant part of pan-African heritage, now grown extensively throughout sub-Saharan Africa, and consumed by some two hundred million Africans.
While Africa remains the largest cowpea production area, the crop is also grown in Brazil, west India, Myanmar, Sri Lanka, Australia and the USA. Bt cowpeas could be very big business for their suppliers.
Cowpeas naturally produce substances which inhibit protein degradation, suggesting any adverse effects of the novel Bt are very likely to be significantly enhanced.
Increased Bt toxicity and immunogenicity are serious concerns for human safety because cowpeas are so widely consumed. Moreover, in a country where so many farmers grow cowpeas, and a collection of over 15,000 landraces of cowpea is maintained, contamination from Bt gene flow into non-GM crops, including the unique gene-bank, could have serious consequences for an invaluable and irreplaceable resource.
Domesticated cowpeas have over 2000 wild relatives in Africa. Although there are barriers to hybridisation between domestic and wild plants, these are far from complete. Bt gene flow into weeds, which might well have their own substances that prevent degradation of the GM protein, is potentially disruptive to ecosystems well beyond the fields.
OUR COMMENT
We desperately need long-term feeding and environmental studies using up-to-date toxicological analytical methods and the Bt plants we're actually eating, especially those GM (not 'genetically improved') crops with multiple, stacked varieties of Bt-toxin.
Westminster's gung-ho attitude to GMOs could soon flood our bodies and environment with a whole host of GM proteins whose toxicity has never been recognised. Prepare to demand proof not assumptions that Bt plants are safe.
SOURCES
·
Are GM plants with Bt toxins 20 times more
toxic than previously known? GM Watch, 21.12.20
·
Susan C. MacIntosh, et al., 1990, Potentiation
of Bacillus thuringiensis Insecticidal Activity by Serine Protease Inhibitors,
American Chemical Society
·
Transgenic cowpea may impact health and the
environment, GM Watch 2.02.22
·
Christoph Then, et al., 2022, Deficiencies
in the Risk Assessment of Genetically Engineered Bt Cowpea Approved for
Cultivation in Nigeria: A Critical review, Plants 11
Image: wild and cultivated cowpea from Wikimedia Commons
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