Proposition 37 on the November ballot has seen the natural food industry and activists on one side and multinational companies, including PepsiCo, Coca-Cola and Kellogg, on the other already raising nearly $4 million combined for campaigns to sway voters one way or the other on genetically modified, or GMO, food products.
The outcome in California could have nationwide impacts, as experts say an estimated 70 percent to 80 percent of processed foods sold in supermarkets could fall under a labeling requirement.
"This will be a big fight," said Shaun Bowler, a University of California, Riverside, political scientist specializing in initiatives, told the Los Angeles Times.
"This is a popular issue because people are very afraid of the words 'genetically engineered.' And the people who sell this stuff are worried about losing sales."
About 50 countries in Europe, South America and Asia have passed labeling requirements for genetically engineered foods, although similar efforts in the United States have so far failed to overcome opposition from the processed food industry, the Times said.