In November, voters will decide whether to make California the first state in the nation to require labels on most genetically modified food products. At least 18 states, including California, have tried to pass similar laws through their legislatures and failed. This time, however, the measure made it to the statewide ballot with 1 million citizen signatures; recent polls show Proposition 37 winning by a significant margin. Food activists across the country are watching the California battle closely, with opponents of genetic modification hoping to make the proposition a model for other states. Supporters of the law, including organic trade groups and environmentalists, say consumers have a right to know if the food they're eating contains genetically modified material - particularly when the long-term health effects are unclear. Seventy percent to 80 percent of processed foods sold in the U.S. are made with genetically engineered ingredients, including corn, soybeans, sugar beets and cotton oil. If the California measure passes, processed genetically engineered food products would include the words Partially produced with genetic engineering" on the front or back label. For whole foods such as sweet corn or salmon, grocers would be required to have a sign on the shelf. Alcohol, most meat, eggs and dairy products would be exempt. Jeffrey Smith, the executive director of the Institute for Responsible Technology based in Iowa, said "Based on the evidence - damage to virtually every organ evaluated and immune and gastrointestinal problems - labels are needed."