Paris - About a third of living Nobel laureates - 108 at last count - have signed an open letter Thursday which attacks Greenpeace for campaigning against genetically modified crops, especially one called Golden Rice.Addressed to the global environmental group, the United Nations and governments, the letter says Greenpeace has "misrepresented the risks, benefits and impacts" of genetically altered food plants."There has never been a single confirmed case of a negative health outcome for humans or animals from their consumption," wrote the top scientists.The group included 41 Nobel medicine laureates among them James Watson, honoured in 1962 for co-discovering the basic structure of DNA.The letter called on Greenpeace to "cease and desist" in its efforts to block GMO crops, and on governments to embrace "seeds improved through biotechnology"."Opposition based on emotion and dogma contradicted by data must be stopped."The Nobel winners singled out Golden Rice as a genetically modified crop with huge potential to improve health and save lives in the developing world.Vitamin A A patented strain developed in the 1990s, Golden Rice contains an artificially inserted gene which boosts the level of vitamin A-rich beta-carotene.The World Health Organisation estimates that a quarter of a billion people in developing nations suffer from vitamin A deficiency, causing up to two million preventable deaths per year and half-a-million cases of childhood blindness.Golden Rice's developers say a single serving provides about 60% of daily vitamin A requirements. It is currently distributed royalty-free to indigent farmers on a humanitarian basis.Greenpeace, however, hit back at the Nobel laureates."Accusations that anyone is blocking genetically engineered 'Golden' rice are false," Wilhelmina Pelegrina of Greenpeace Southeast Asia wrote in a statement.Corporations are using the strain "to pave the way for global approval of other more profitable genetically engineered crops", she said.Greenpeace's longstanding position is to oppose all patents on plants or animals, or their genes, and that "life is not an industrial commodity".Previously, the environmental NGO has said Golden Rice was "environmentally irresponsible, poses risks to human health, and could compromise food, nutrition and financial security".The NGO also maintains that genetically modified organisms should be held back "since there is not an adequate scientific understanding of their impact on the environment and human health".