If Proposition 37 passes, California would become the first state in the nation to require new labels on a host of food products commonly found on grocery store shelves. Many other nations, including Japan, China and a host of European countries, already label genetically engineered food. In the United States, however, products that contain genetically engineered ingredients are generally not labeled. Proponents ... have raised $2.8 million. A company owned by Joseph Mercola, a controversial holistic health activist from Illinois with more than 100,000 Twitter followers, has kicked in $800,000. Opponents have raised nine times as much. Almost all of the nearly $25 million has come from a variety of chemical, seed and processed-food companies. Monsanto, a leading producer of genetically engineered seeds, donated $4.2 million, the largest donation. The labeling initiative largely covers processed foods. Milk, cheese and other dairy products made from cows that are injected with the bovine growth hormone or eat genetically engineered feed like alfalfa would be exempt, but meat or dairy products from animals that are genetically engineered would be labeled. In 2000, 25 percent of the corn planted in the United States was genetically engineered, according to the U.S. Department of Agriculture. By 2012, that figure had soared to 88 percent. The group California Right to Know, which is leading the pro-labeling campaign, is counting on a vast social media network and volunteers to get its message out. Stacy Malkan, a spokeswoman for the yes campaign, said [this] "is a people's movement against out-of-state corporations."