A Scientific Look at Genetically Modified Crops
WILL GENETICALLY ENGINEERED CROPS MEAN ADULTERATED AND TOXIC FOOD, BODIES, AND ECOSYSTEMS?
(Publisher's note -- this article is a bit challenging to read, but we think you will appreciate its sophistication.)
by Dr. Michael W. Fox, Senior Scholar/ Bioethics
The Humane Society of the United States
2100 L Street, NW
Washington, DC 20037
Without any scientifically or empirically verified evidence, advocates of agricultural biotechnology claim that genetically engineered (GE) or genetically modified (GM) crops are the answer to world hunger and will give security to an ever increasing population. They claim that by making conventional "production" agriculture efficient, biodiversity can be protected and endangered species saved.
There is increasing scientific evidence to the contrary, which is why Great Britain is leading the European Economic Community to put agricultural biotechnology on hold until more is known about the risks and benefits of GE crops, foods, additives supplements (enzymes, vitamins, etc.); to more carefully monitor and effectively regulate agribiotechnology; and to apply the precautionary principle to this new technology.
At the 12th (1999) annual Scientific Conference of the International Federation of Organic Agriculture Movements (IFOAM), more than 600 delegates from over 60 countries voted unanimously for a declaration against the use of genetically modified organisms in food production and agriculture. The delegates called on governments and regulatory agencies throughout the world to immediately ban genetic engineering in agriculture and food production since it involves:
- Negative and irreversible environmental impacts.
- Release of organisms of an unrecallable nature.
- Removal of the right of choice, both for farmers and consumers.
- Violation of farmers' fundamental property rights and endangerment of their economic independence.
- Practices which are incompatible with the principles of sustainable agriculture as defined by IFOAM.
- Unacceptable threats to human health.
To regard many genetically engineered (GE) crops and food as being adulterated and even potentially toxic, and therefore posing potential risks to human and other consumers (including insects, birds, and wild and domesticated mammals) and to the environment is not unreasonable considering the following scientifically documented findings:
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- There is evidence that foreign DNA can enter the body via the gastrointestinal tract and cross the placenta (1,2).
- Genetically modified organisms can produce unanticipated toxins (3,4) or allergens (5).
- Gene transfer can occur between transgenic plants and bacteria, the ecological consequences of which can be catastrophic (6).
- Milk from cows injected with r-BGH, which is not analogous to normal BGH (7), has elevated insulin-like growth factor that is implicated as a risk factor in human breast cancer (8,9).
- Considering the documented evidence that horizontal transfer between species is a natural phenomenon (10-16), the precautionary principle must be applied in creating transgenic organisms that could transfer novel genes and viral vectors to other species (17-19). The ecological, evolutionary, and public health consequences of such transfers we will only know after the fact. Horizontal gene transfer is even likely to take place in the digestive systems of protozoa, nematodes, insect larvae, and other soil macro-organisms (12).
- That genes, like viruses, can infect (20,21), should serve as a warning to us all of the potential risks of transgenic organisms serving as reservoirs for new diseases, and as a medium for the evolution of new pathogens because of their altered physiology and biochemistry.
- Unanticipated multiple side effects of gene insertion (called pleotropic effects) have been well-documented. Viral "promoters" and "enhancers" that boost expression of transgenes could result in the production of high levels of Bt toxin and other chemicals in transgenic crops. Even more serious harm to the ecology of the soil may result, because this Bt toxin does not rapidly degrade in certain soils after the crop has been harvested and the remains used compost. This toxin in transgenic crops is likely to accumulate more and more in the soil after each crop, and will poison many beneficial insects and other organisms essential for the ecological health and fertility of the soil. This could effect the nutritive value of crops grown in sterilized soil. (22) Genetic alterations in crops like soybeans to make them resistant to herbicides may result in unpredictable, unnatural genetic recombinations and change the biochemistry and nutritive value. Higher levels of phyto-estrogens are produced in beans grown in the presence of the herbicide glyphosate, which may be of particular risk to children (23).
- The highly controversial research findings of a reputable scientist, Dr Arpal Pusztai from the UK government's Rowett Research Institute, revealed adverse health effects in rats fed genetically engineered potatoes. He reported abnormal organ development and weakening of the immune system attributable to either the cauliflower mosaic virus that was used as a promoter (and in many other transgenic crops), or to the active genetically spliced insecticidal lectins present in these GE potatoes. Liver, brain, and heart sizes of the rats all decreased. (24)
- Some 99 percent of commercial transgenic crops incorporate virus genes, either as promoters or to control virus infections. These virus genes can recombine with other viruses and may result in new diseases and more invasive pathogens (25-29). With the inclusion of antibiotic-resistance markers, transgenic crops could therefore increase the probability of new viral and bacterial pathogens and the spread of antibiotic and drug resistance genes.
- DNA released from living and dead cells can persist in the environment and be transferred to other organisms. An organism may be dead, but its "naked" DNA released from decaying cells may remain biologically active for potentially thousands of years, especially in certain soils and marine sediments. (30) Naked DNA (nucleic acids) ingested by mice can be transferred to offspring and be voided and spread in animals' feces. (2)
- One must therefore consider not only the "fate" of transgenic organisms but also the genes and viruses or parts thereof, that have been inserted into them. Such "naked DNA", in the form of recombinant and modified nucleic acids, has been found capable of surviving and remaining functional longer after organisms' death than was assumed previously.(6,30) Furthermore, xenobiotics, especially dioxins and various agrichemicals, can act as mutagens (31), altering the structure and sequence of DNA and also increasing the permeability of cells and the incorporation of foreign DNA into living organisms.
- The instability of transgenic crops is a major concern. There is, in fact, no data documenting the stability of any transgenic line in gene expression, or in structure and location of the insert in the genome. Such data must include the level of gene expression, as well as a genetic map and DNA base sequence of the insert and its site of insertion in the host genome in each successive generation. No such information has been provided by industry, nor requested by regulatory authorities. (32)
Conclusions: Contamination of the "life stream" by naked recombinant DNA, by transgenic viral vectors, and antibiotic resistant genes is probably already taking place. Since a recall is impossible, our best hope if it is not already to late to control genetic pollution, is a five-year worldwide moratorium on the creation and release of all genetically engineered living entities and products, from new vaccines, to transgenic crops, so that science-based risk assessments can be properly completed.
POSTSCRIPT The British Medical Association released an interim statement on "The Impact of Genetic Modification on Agriculture, Food and Health", citing a critical need for more data on allergenicity and possible toxicity of GM foods. This statement included the following points concern:
- Information about the effect of genetic modification on the chemical composition of food, and in particular its safety is needed urgently.
- Adverse effects are likely to be irreversible; once GMO's are released into the environment they cannot be subject to control.
- The BMA rejected the notion that GM foods should be assumed to be safe when they are said to be substantially equivalent to their conventional counterparts, which is the basis of U.S. regulation of biotech foods. "This concept does not account for gene interaction of unexpected kinds, which may take place in GM foods," the statement asserts. "The possibility that certain novel genes inserted into food may cause problems to humans is a real possibility, and 'substantial equivalence' is a rule which can be used to evade this biological fact."
- Among several recommendations, the BMA urged that:
- the precautionary principle should be applied in developing genetically modified crops or foodstuffs, as we cannot at present know whether there are any serious risks to the environment or to human health involved in producing GM crops or consuming food products.
- Careful consideration needs to be given to the effect of GMO's on farming practices, the countryside and wildlife and we therefore recommend a moratorium on the commercial planting of GM crops in the UK. The moratorium should continue until there is scientific consensus (or as close agreement as reasonably achievable) about the potential long-term environmental effects.
- GM foodstuffs should be segregated at source, to enable identification and traceability of GM products.
- There should be a ban on the use of antibiotic resistance marker genes in GM food, as the risk to human health from antibiotic resistance developing in micro-organisms is one of the major public health threats that will be faced in the 21st Century.
- The risk that GM crops may increase the use of herbicides and pesticides in the environment needs to be comprehensively assessed to determine their full environmental impact.
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