"Nonsense," said Brian Castillo, a spokesman for the opposing "No on 37" campaign. "There is no scientific justification for labels."

He said the labels are simply a way to scare consumers. "Requiring a label on a product implies that there is something wrong with these foods when the science, when the World Health Organization, the American Medical Association all says there is not. "

Castillo said modifying crops has been practiced by farmers since they first planted seeds.

"If you get into the history of this, we've been genetically modifying crops for thousands of years. In recent decades through biology and modern science, we're able to be much more efficient and frankly safer about it," he said. 

He said Sprinkel and his fellow organics have a "hidden agenda"

"We think the true motive ... is to ban these foods," he said. "The proponents of these are anti-science extremists who want to ban these perfectly safe foods."