In a dramatic turnaround, British Prime Minister Tony Blair on Sunday acknowledged what most people in his country have long believed: that genetically modified crops may pose risks to human and environmental health. “There is no doubt that there is potential for harm, both in terms of human safety and in the diversity of our environment, from GM foods and crops,” Blair wrote in the London Independent, in marked contrast to comments he made a year ago when he was aggressively promoting GM technology and blaming the media and enviro groups for stirring up public outcry. Blair still contends that GM technology could bring benefits to society, but he says the government will proceed with caution. Enviros welcomed Blair’s change of heart, and some senior government sources said the shift likely indicates a turning point in British GM policy.