Greenpeace, Friends of the Earth, and other enviro and public interest groups are trekking to Montreal, Canada, planning to raise their voices against genetic engineering as U.N. talks on the issue start Monday. Representatives of 134 nations will convene to discuss a proposed Biosafety Protocol, which is intended to establish rules for the international movement of genetically modified organisms in order to protect the world’s plants and animals from potentially adverse effects. Many scientists and activists are concerned that GM crops could cross-pollinate and contaminate native species, potentially wrecking havoc on ecosystems. International trade issues will play a large part in protocol talks. The U.S. and Canada, as well as other exporters of genetically modified crops, are expected to try to sway countries in Europe, Africa, Asia, and Latin America that want the right to ban GM crops to protect the environment and public health.