A panel of business leaders in the natural foods industry — included executives at Whole Foods Market and Amy’s Kitchen — took to their phones on Thursday in a conference call to reporters in support of California’s Proposition 37 to require the labeling of products containing genetically modified (GM) foods.

Since consumers determined to avoid GM foods already shop at their stores and buy their products, the panel said they stand to lose business if the measure passes on Nov. 7, but they favor it because it’s the “right thing” for America. If GM-wary customers could make educated shopping choices at big-box grocers, they argued, they might no longer make the trek out to the specialty stores.

“This may be a little bit of shooting ourselves in the foot,” said Jimbo Someck, CEO of Jimbo’s Naturally, a natural foods grocer in southern California.

After several newspapers published editorials against the measure in recent weeks, pubic opinion has gone into a dead-heat, said Ken Cook, president of the Environmental Working Group, which organized the call.

A recent poll placed 44 percent of voters in favor and 42 percent against Prop. 37. That same polling group found 65 percent in favor back in August, Cook said.

EWG intended for the call to dispel claims against Prop. 37 put forth by the ‘No on Prop. 37’ campaign, which has outspent the ‘Right to Know’ campaign roughly 10 to 1. On its website, ‘No on Prop. 37’ says the measure would increase annual family grocery bills by $400 and open the door to ‘shakedown’ lawsuits targeting farmers and grocers. But that’s not the case, the panelists argued.

For example, the price of dairy products in the United Kingdom – which requires labels on GM foods – is approximately 25 percent lower than in the U.S., said Andy Berliner, CEO of Amy’s Kitchen. He added that Coca-Cola is made without GM ingredients for European markets and yet remains priced comparatively to soda in the U.S.

Numerous times during the call, panelists stressed that GM crops can incur greater environmental consequences than their conventional counterparts, such as a need for heightened levels of pesticides.

A report published Wednesday in the Los Angeles Times, however, states the opposite: “About 90% of the corn, soy and cotton now grown in the U.S. is genetically modified, and that has led to less use of pesticides, more targeted insect control, a shift to fewer toxic chemicals and less soil erosion compared with conventional farms, according to a 250-page analysis from the National Academies in 2010.”

Those on the ‘Right to Know’ side of the fence expect California to lay the groundwork for an eventual federal GM labeling law. Such laws currently exist in 61 countries.