Scientific findings

Genetic pollution through pollen or seed dispersal:
* Gene transfer from crop radish to wild weedy relatives has been detected over distances of one kilometre (Klinger et al., 1992). Klinger and Elstrand studied as well the fitness of weed-crop hybrids(crossbreeds) of radish. The crossbreeds showed significantly greater fruit and seed production, and in all other measured characteristics the hybrids were like weeds. Their results suggest that neutral or advantageous transgenes introduced into natural population will tend to persist in wild populations (Klinger & Elstrand, 1994).
* Field tests with genetically engineered potatoes have demonstrated both the high frequency and wide range of gene flow. When normal potato plants were planted in distances up to 1100 metres from genetically engineered potatoes, and the seeds were collected afterwards, 72% of the plants in the immediate neighbourhood of the transgenic potatoes contained the transgene. At greater distances an almost constant 35% of seeds contained the transgene (Skogsmyr, 1994).
* Scientists at the Scottish Crop Research Institute have shown that much more pollen escapes from large fields of genetically engineered oilseed rape than is predicted from earlier experiments on smaller plots. They found that escaping pollen fertilised plants up to 2.5 kilometres away (Timmons, 1994)
* Joergensen and Andersen (1994) showed how easily oilseed rape crossbreeds with wild relatives and therefore how easily transfer of the herbicide resistance gene could occur. Within the first season they estimated that a substantial part of wild weed population could acquire the gene for herbicide tolerance. (Joergensen & Andersen, 1994, Mikkelsen, et al., 1996)
* Crop seeds travel hundreds of kilometres between seed merchant, farmer and processing factory, therefore spillage in transport is inevitable - and could be more worrying than threat through pollen spread (Crawley, 1996).

The risk of transfer of foreign gene to micro-organism
* It was reported in 1994 that gene transfer can occur from plants to micro-organisms. Genetically engineered oilseed rape, black mustard, thorn-apple and sweet peas all containing an antibiotic-resistance gene were grown together with the fungus Aspergillus niger or their leaves were added to the soil. The fungus was shown to have incorporated the antibiotic-resistance gene in all co-culture experiments (Hoffmann et al., 1994). It is worth noting that micro-organisms can transfer genes through several mechanisms to other unrelated micro-organisms.
* This risk caused UK Environment Department's Biotehnology Unit to advise the UK government to vote in the EU against the authorisation for placing onto the market of Ciba Geigy's transgenic corn in 1996: "the presence of an intact gene for resistance to beta-lac tam antibiotics poses an unacceptable risk because consumption of the unprocessed product as animal feed could lead to the transfer of the gene to the gut microflora of animals." Ciba Geigy's genetically engineered corn contained among other foreign genes a gene for resistance against Ampicillin antibiotics (beta-lac tam antibiotics).

Nasty surprises
* Genetically engineered soil bacteria Klebsiella: A common harmless variety of a bacteria Klebsiella planticola, inhabiting the root-zone of plants had been genetically engineered to transform plant residues like leaves into ethanol that farmers could readily use as a fuel. The genetically engineered bacteria not only survived and competed successfully with their parent strain in different soil types, it proved unexpectedly to inhibit growth or kill off grass in different soil types tested. In sandy soil, most of the grasses died from alcohol poisoning. In all soil types the population of beneficial mycorrhizal fungi in the soil decreased. These soil fungi are crucial for plant health and growth as they help plants to take up nutritions and to resist common diseases. In clay soils, the genetically engineered bacteria increased as well the number of root-feeding nematodes. (Holmes and Ingham, 1995).
* Genetically engineered salmon: The transgenic salmon was engineered with an arctic flounder gene for increased cold tolerance. However, this transgenic salmon grows ten times as fast as normal salmon as the genetic modification resulted in an increased activity of the salmon's own growth hormone gene (MacKenzie, 1996).
* The bacteria Pseudomonas putida was genetically engineered to degrade the herbicide 2,4-D. The engineered bacteria broke down the herbicide but degraded it to a substance that was highly toxic to fungi. These fungi - crucial to soil fertility and in protecting plants against diseases - were therefore destroyed (summarised in Doyle et al., 1995).
* The toxin-producing gene of the bacteria Bacillus thurigiensis, for instance, is commonly engineered into crops to provide them with a built-in insecticide. However, the toxin produced is known to resist degradation by binding itself to small soil particles whilst continuing its toxic activity. The long term impact of this toxin on soil organisms and soil fertility is unknown (summarised in Doyle et al., 1995).

Deadlier viruses
* Genetically engineered virus resistant crops may cause the development of new kinds of plant viruses due to recombination events. Scientists published a study demonstrating that virus genes implanted into plants cells could be transfered into the genome of other viruses that the plants come into contact with (Greene and Allison, 1994). This could lead to the unintentional creation of new, and perhaps more virulent, plant viruses.

* A new study showed that genetically engineered soybeans containing one foreign Brazil nut gene could cause allergic reactions in Brazil nuts sensitive humans (Nordlee et al., 1996). The discovery of the allergenic potential of Pioneer's genetically engineered soybean prior to its use as human food sources was thanks to a unique advantage: the donor organism for the gene, Brazil nut, was a known food allergen, and serum samples of persons known to be allergic to Brazil nuts were available for testing. However, in many cases it is not genes from long known food plants that are transfered into crops. Genes from bacteria which have never been part of the diet are more common components. This is the case with Monsanto's RRS. Who knows what the allergenic potential of this newly introduced gene product will be? It is uncertain, unpredictable and untestable (Nestle, 1996).


* Crawley M (1996) 'The day of the triffids'. New Scientist 6 July pp 40-41
* Doyle JD, Stotzky G, McClung G & Hendricks CW (1995) Effects of Genetically Engineered Micro-organisms on Microbial Populations and Processes in Natural Habitats, Advances in Applied Microbiology, Vol.40 (Academic Press)
* Greene, A.E. and Allison, R.F. (1994) Recombination between viral RNA and transgenic Plant Transcripts, Science Vol.263, 11 March 1994
* Hoffmann T, Golz C & Schieder O (1994) Foreign DNA sequences are received by a wild-type strain of Aspergillus niger after co-culture with transgenic higher plants. Curr.Genet.27:70-76
* Holmes TM & Ingham ER (1995) The effects of genetically engineered microorganisms on soil foodwebs. in "Supplement to Bulletin of Ecological Society of America 75/2, Abstracts of the 79th Annual ESA Meeting: Science and Public Policy" Knoxville, Tenesse, 7-11 August 1994.
* Joergensen RB & Andersen B (1994) Spontaneous Hybridization between Oilseed Rape (Brassica napus) and Weedy B. Campestris (Brassicaceae): A risk of growing genetically modified oilseed rape. American Journal of Botany, 81(12), P. 1620-1626.
* Klinger T and Ellstrand NC (1994) Engineered Genes in Wild Populations: Fitness of Weed-Crop Hybrids of Raphanus sativus Ecological Applications Vol.4, No 1:117-120
* Klinger T, Arriola PE & Ellstrand NC(1992) Crop-weed hybridization in radish ( Raphanus sativus L.): Effects of distance and population size. Am. J. Bot.79:1431-1435.
* MacKenzie D. (1996) Altered salmon grow by leaps and bounds, New Scientist, 6 January 1996
* Mikkelsen TR, Andersen, B., and Jorgensen R.B.(1996) The risk of crop transgene spread, Nature Vol 380, 7 March 1996.
* Nestle M (1996) Allergies to transgenic foods - question of policy, The New England Journal of Medicine, Vol 334, No 11:726-728
* Nordlee JA, Taylor SL, Townsend JA, Thomas LA and Bush RK(1996) Identification of a brazil-nut allergen in transgenic soybeans, The New England Journal of Medicine, Vol 334, No 11:688-692
* Skogsmyr I (1994) Gene dispersal from transgenic potatoes to conspecifics: A field trial. Theor.Appl.Genet.88:770-774
* Timmons AM, O'Brian BT, Charters YM & Wilkinson MJ (1994) Aspects of environmental risk assessment for genetically modified plants with special reference to oilseed rape. Scottish Crop Research Institute, Annual Report 1994. SCRI, Invergowrie, Dundee, Scotland.
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