Are there dangers in genetic modification?

What you need to know.

A. Genetic transformation can go wrong
B. Genetic transformation weakens
C. An infinite potential to produce toxins
D. Without soil, we have no food
E. Food allergies are escalating
F. Damaging the integrity of life
G. References

A. Genetic transformation can go wrong

Building complex molecules you can't see, and inserting them into living cells are imprecise processes. You can never quite tell what you're actually creating.

Here are some examples from science.

OBSERVATION A1
In one of the simpler applications of genetic engineering, genetically transformed bacteria were used to produce a bovine growth hormone for injection into dairy cattle to boost milk production. Once on the market, independent research revealed that the hormone had a substitution in one of its constituent amino acids.(1)

Genes instruct the cell to produce the proteins needed to maintain the life processes. Proteins can consist of many thousands of amino acid building blocks. The substitution of a single amino acid, in even the largest protein, can mean the difference between a toxic or non-toxic, stable or unstable, biologically functional or non-functional product.(2)

OBSERVATION A2
The bacterium, Bacillus thuringiensis (Bt) can be sprayed onto crops where it exerts useful insecticidal properties, after which it quickly decomposes. When plants are genetically transformed to generate single look-alike Bt toxins, these have been found to bind to soil particles. In this form, they can exert long-term toxic effects and disturb the soil ecosystem.(3)

A single substance produced outside its native living context, will always be beyond the natural control mechanisms which would otherwise protect against damaging effects. The transfer of an isolated engineered gene into a host introduces just such a substance.

OBSERVATION A3
A bacterium was genetically transformed four times to increase its production of L-tryptophan for commercial extraction and sale as a nutritional supplement. The presence of trace amounts of a toxic tryptophan derivative was responsible for 37 deaths and 1,511 cases of crippling neurological disease in the U.S.A. alone. The combination of genetically transformed bacteria and an obviously inadequate purification process was to blame, but the question of how the toxin came about will never be answered because the bacterial culture was destroyed without investigation.(4)

The imprecise nature of genetic transformation makes it impossible to recreate another identical organism, even using exactly the same techniques. Every genetically transformed form of life has its own, unique biology, and is unlike any natural life-form ever studied.

OBSERVATION A4
Rats fed on potatoes genetically transformed to produce a lectin (insecticide) known to be safe to mammals were found to have alarming changes in growth, organ development and immune reactivity. These effects weren't derived from the lectin, nor the lectin-producing gene, but from something in the wider genome (24)

OBSERVATON A5
Aubergines genetically transformed to produce an artificial Bt toxin (see A2) were found to have 15% fewer calories and a different alkaloid content. The dairy cows fed these GM aubergines were found to have increased weight, eat more dry roughage matter and had increased milk production similar to the effect of treatment with hormones. (23)

OBSERVATION A6
Potatoes genetically transformed with a very commonly used marker gene (nptII-gus) and no other trait were found to be much more attractive to a common pest, the larvae of the Colorado beetle. (5)
None of these results can be explained.

One major technique used to transform plants involves bombarding isolated cells with particles coated with the artificial DNA. One in every ten thousand cells incorporates the foreign gene and becomes transformed. The only predictable thing about this process is the random damage to the plant's own DNA. (6)
(Other techniques are somewhat less disruptive, but can go wrong in other ways - see Horizontal Gene Transfer).

B. Genetic transformation weakens

The disruption to the life processes caused by the insertion of a foreign gene, plus the effect of being forced to produce an unnecessary and alien substance, place a strain on the genetically transformed organism.

OBSERVATION B1
Genetically transformed oilseed rape was found to have much poorer over-winter seed survival than its parent strain.(7)

OBSERVATION B2
Petunias, genetically transformed to produce a more marketable flower colour, were found to loose the artificial colour when stressed by environmental factors and old age.(8)

OBSERVATION B3
GM soya genetically engineered to be tolerant to glyphosate herbicide is now a major monoculture in North and South America. It is subject to stem splitting in adverse conditions, due to over-production of lignin. The crop also has deficient manganese metabolism and needs to be heavily supplemented with the mineral. (33,34,35)

Increased susceptibility to stress is an inevitable consequence of genetic transformation.

OBSERVATION B4
"While there are some examples of plants which show stable expression of transgenes these may prove to be exceptions to the rule. In an informal survey of 30 companies involved in the commercialization of transgenic crop plants, which we carried out for the purpose of this review, almost all respondents indicated that they had observed some level of transgenic inactivation. Many respondents indicated that most cases of transgenic inactivation never reach the literature." (9)

Weaknesses arising from the engineered trait or transformation process will be catastrophic to the crop yield. Transgenic failures are not reported in the scientific literature.

C. An infinite potential to produce toxins

Every natural substance in the living organism can become toxic if it turns up in the wrong place at the wrong time or in the wrong amount.

OBSERVATION C1
A yeast transformed with multiple copies of its own genes to boost fermentation accumulated a natural metabolite, methyl-glyoxal, in amounts that were toxic and capable of damaging DNA.(10)
The disturbance of normal living processes by the genetic transformation of the cell is likely to lead to multiple metabolite imbalances. While acute toxic effects (as described in A3) may be unusual, chronic small doses of a toxin can produce profound long-term damage, especially to the developing foetus and infant (11), while the presence of a cocktail of toxins could have synergistic damaging effects.

OBSERVATION C2
Genetically transformed tobacco given a bacterial gene to produce gamma-linolenic acid, produced mainly the novel toxin octodecatetraenic acid.(12)

Identifying an unknown toxin is like looking for a needle in a haystack when you don't even know what the needle looks like.

The trace toxin associated with tryptophan from a genetically transformed source (see A3) was only identified after a mammoth US-wide investigation. Finding it was only possible because it caused a disease with highly specific symptoms, and because the offending substance was supplied in precisely labelled bottles. The odd health effects such as those described in A4 and A5 would never be detected in the general population, even if they killed thousands of people.

We are unlikely to be so lucky next time.

D. Without soil we have no food

The soil is a poorly understood complex of life, water, and organic and inorganic matter, and all-important water in intimate association.(13) Its ability to support healthy plants depends on the constant and balanced cycling of life, matter and water.

OBSERVATION D1
A common, harmless root-zone bacterium was genetically transformed to produce ethanol for fuel from vegetable matter. Its effect in the soil was to displace the parent strain and promote root-feeding nematode pests while inhibiting plant growth and the soil fungi.(14)

OBSERVATION D2
A bacterium genetically transformed to degrade a herbicide produced a substance highly toxic to soil fungi.(3)

OBSERVATION D3
Bt maize crop detritus and pollen make their way into streams where they can be sequestered, consumed or carried considerable distances (see A2). Aquatic animals exposed to the run-off from fields have been found to be harmed by at least one form of man-made Bt toxin in their diet.(25,27)

OBSERVATION D4
Bt toxin (see A2) enters the soil in root exudates from GM plants. At least two types of Bt crop reduce the decomposition of litter in the soil. (28)

OBSERVATION D5
Observations over three successive years of Bt cotton planting found that major humus-creating bacteria had declined by 17%, and that the microbial enzyme activity which makes nutrients available to plants had declined by 22-26%. (26)

GM crops are being genetically transformed with a host of different, completely artificial, variants of Bt toxins (see A2). A GM maize stacked with six different artificial Bt toxins is due for commercialisation in 2010. These are all toxic to soil life, and many may be cumulative in the soil and spread through the environment in water.

Catastrophic disruption of the soil ecosystem is a real possibility when genetic engineers try to get clever. These instances represent a short sharp wake-up call not to interfere in biological systems we don't understand. The slow erosion of soil fertility by successive waves of genetically transformed, self-replicating microbes cannot be reversed.

E. Food allergies are escalating

Known allergens can be identified because we have human serum from previous reactants which we can use to test for them. Potential allergens can occasionally be identified because they contain chemical groups already recognised to be a commonly allergenic. Completely novel allergens cannot be identified until they arise.

OBSERVATION E1
Allergens may not become obvious until 4-5 years of sensitisation has been on-going.(30)

OBSERVATION E2
World-wide historical statistics show that:
  • since the mid-1990s when GM entered the human diet, allergy rates have steadily increased across all age-groups
  • increased or static incidence of allergies in a country can be related to the absence or presence of precautionary restrictions on GM entering the diet
  • in one country which has very restrictive policies on GM, severe allergic reactions amongst 0-4 year olds have been as little as one ninth of those recorded in countries which have allowed GM (29).
OBSERVATION E3
"One major concern over transgenic foods is their potential to be allergenic, which has become a concrete issue since a transgenic soybean containing a Brazil-nut gene was found to be allergenic (see BOX F4). Studies suggest that allergenicity in plants is connected to proteins involved in defense against pests and diseases." (15,16,17)

Genetic transformation and its consequences are likely to stimulate the plant's immune system as a reaction to the genomic damage and to the increased sensitivity to stress (see B).

OBSERVATION E4
Bt toxin in its natural forms (see A2) was found to cause immune reactions in 70% of farm-workers exposed to it.(30)

OBSERVATION E5
A gene commonly inserted into approved herbicide-tolerant crops such as oil-seed rape to prevent the applied weedkiller accumulating in the plant has been recognised as being potentially cross-reactive with allergens found in prawns, shrimp and lobster. The European Food Safety Authority has stated that “persons allergic to shrimp meal should be aware of the possibility of hypersensitivity” when working with such products.(32)

The above suggest that regulators aren't taking allergy-assessment very seriously.

OBSERVATION E6
Peas (which have no history of being allergenic) were genetically transformed with a gene copied from a bean (which has no history of being allergenic). The GM peas produced a bean protein (which had no history of being allergenic). The GM peas not only induced immune reactions to the pea itself, but induced allergic reactions to other common proteins in other foods. (31)

OBSERVATION E7
The GM lectin described in A4 caused an immune reaction in the gut.

Allergens which cause reactions in the digestive tract will be crippling to health.

F. Damaging the integrity of life

To persuade man-made genes to enter the host genome, they have to be attached to pieces of DNA which will enable them to invade.

OBSERVATION F1
A plant normally self-pollinating dramatically increased its ability to donate pollen to nearby wild types after genetic transformation.(19)

OBSERVATION F2
Test DNA fed to mice was found transiently in their white blood cells, spleen and liver. When it was fed to pregnant mice, the DNA was found in parts of the foetus.(18)

Is it surprising that DNA designed to be mobile finds ways to move?

OBSERVATION F3
Viral DNA sequences which 'switch on' the engineered genes are added to practically all commercialized genetically transformed crop plants.(19) These viral sequences have been shown to recombine with natural disease-causing viruses in plants to cause the emergence of a much more virulent form.(20)

OBSERVATION F4
In an attempt to make it more suitable for animal feed, soya was genetically transformed with a gene from the Brazil nut to boost its methionine-rich albumin content. This substance is not known to be capable of causing any allergic reactions, but the transformed soya inexplicably gained a nut allergenicity.(21)

The transfer of a single gene appears, in this case, to have conferred some additional, more subtle, nut characteristics to the soya. We don't know why.

In the present situation, we are transferring many genes from potentially pathogenic organisms into the plants of our food chain; for example, E. coli genes are now present in genetically transformed maize which is a large part of our livestock feed. The discovery that the pathogenic E. coli 0157 has achieved its notorious toxicity by acquiring toxin genes from other species should perhaps make us wary of a genetic interference in our food which might confer a similar trait.(22)

G. References

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