Alongside the national push, the GMO labeling debate is also active in California, where a grassroots coalition of consumer, public health and environmental organizations has submitted what it calls the "California Right to Know Genetically Engineered Food Act" to the state Attorney General.
Backers of the measure must obtain more than 500,000 signatures by April 22 to get it on the November ballot. They say that in addition to giving consumers information about what they are eating, labeling would also allow health professionals to track potential adverse health impacts of GMO foods.
The question of safety is separate, though related, from the issue of labeling, according to Mellman.
"Calories aren't unsafe... but people want to know what they're ingesting," he said.
A recent study by the Grocery Manufacturers Association said about 80 percent of packaged foods contain genetically engineered ingredients.
Leading biotech crop developer Monsanto Co. and other agricultural biotech seed companies are opposed to labeling, saying it misleads consumers and there is no safety concern with GMOs.
As well, opponents of labeling say mandatory labeling would be costly, increasing food prices for consumers, cost taxpayers for enforcement, and trigger costly litigation.
More than 40 countries have some requirements for labeling of genetically engineered foods, with Europe a prominent leader in mistrust of genetic alterations to crops.