Two American experts have refuelled the controversy over genetically modified(GM) crops by saying no one can be certain of the risks or benefits, TheIndependent newspaper writes today. The scientists, from the US EnvironmentalProtection Agency, said that genetic engineering and selective breeding maynot have the same long-term effects. "As more economically useful andhealth-related genes are identified and isolated, it appears that the varietyof genetically engineered organisms will increase dramatically. This increasemay collectively represent an environmental risk," wrote LaReesa Wolfenbargerand P. R. Phifer, in the journal Science. The US Environmental ProtectionAgency is currently involved in a dispute with the US Department ofAgriculture, which has allowed the commercial planting of thousands of acresof GM crops such as soya and maize. No GM crops have been approved forcommercial planting in Britain, pending the results of ``field trials'' toassess the impact. There is now growing consumer pressure in America forlabelling to be applied to GM-derived food, as it is in Europe.