Unexplored threat to health, wildlife and biodiversity
Scientists give warnings on allergies and cross-pollination
Paul Brown
The Guardian, Tuesday July 22, 2003
http://www.guardian.co.uk/gmdebate/Story/0,2763,1003379,00.html

Health effects

To date, worldwide, there have been no verifiable untoward toxic or nutritionally bad effects from GM products - but that does not mean there will not be any, the government's GM science review concludes.

There has been no study of the effects on people of eating GM food and none has yet been developed, the report says.

One of the potential problems in food is possible allergies caused by GM crops. Each new crop must be taken on a case by case basis, and although so far no allergies have been noted the possibility is there because of the introduction of new proteins into food.

The scientists say it is vital for labelling, traceability of the food content and recall systems to be of a very high standard so if a problem arose the consumer could be safeguarded. Either the GM product which caused the allergy should be clearly labelled or withdrawn from the shops. 

"Our relative lack of knowledge about factors that are important in sensitisation and elicitation of an allergic response suggest we should continue to exercise caution when assessing all new foods, including foods and animal feeds derived from GM crops," the report says.

The use of antibiotic market genes in GM crops, which some fear may confer resistance on some bacteria, remains controversial. While the scientists found no evidence it was more than a theoretical problem, the report concluded that since it was no longer necessary to use antibiotics in GM, they should be phased out.

Environmental impact

Intensive agriculture has already led to a significant decline in farmland plants, insects and birds, although the specific role of herbicides on this process was less clear, the report says.

The impact of GM crops which were herbicide tolerant - allowing all other weed plants to be killed - was still being assessed by a government study and the results were eagerly awaited this autumn. However, the report says: "This poses perhaps the most serious potential harm arising from these particular crops."

The scientists were also concerned about how farmers would apply this technology under real conditions. In theory, farmers might use less herbicide, less often, allowing weeds to survive longer, but in practice they might use the technology to wipe out all weeds, further reducing the volume of wild plant seed in agricultural areas, and reducing biodiversity further.

Another potential danger was the development of crops that were tolerant of drought, heat, salt or other soil conditions which made it impossible to grow crops at present. "Such crops could become more successful as weeds, and there could be economic pressure to cultivate areas with wildlife and conservation value."

Gene flow

Cross pollination from GM crops to conventional crops and organic crops is a problem, the scientists say. The transfer of pollen by bees, the contamination of seed in machinery or storage facilities, and the growth of GM crops in conventional fields in the following season from GM plants which have seeded themselves are all potential difficulties.

For some crops, avoiding contamination may be relatively easy, but for others almost impossible. Separation distances between crops and whether it was possible for both GM and conventional crops to co-exist would be a political decision.

Transfer of genes from engineered crops to weeds could produce problem plants into the environment, the report says. The best example of this has occurred in Canada when a weed species acquired resistance to three commonly used herbicides. The weed had acquired genes from three different plants - two GM strains and one conventionally bred - which meant a fourth, more environmentally damaging, herbicide had to be used to kill it. 

This "stacking" of transgenes in wild relatives is a distant possibility in Britain. It would involve creating plants with unintended gene combinations. 

One great potential danger was GM wild plants gaining resistance to insect pests by cross-pollination. This might give them an advantage.

Predicting what will happen as a result of accidental production of wild plants with GM traits was a challenge to the regulatory system.