How can you be sure the products you buy don't contain genetically modified organisms, or GMOs?

You can't, but food advocates are hoping to change that.

What's In A Label?

Non-profit consumer group Consumer Reports released a study sampling 80 popular corn- and soy-based products to find the content of GMOs, including products labeled organic, no-GMO, and "natural."

Consumer Reports found that "certified organic" products met no-GMO guidelines. To be certified organic under USDA regulations, the product must contain no more than 0.9 percent GMO products.

Products certified by the Non-GMO Project and most products labelled no-GMO also met the appropriate standards.

Products labeled "natural," however, proved a different story.

According to Consumer Reports' survey of 1000 adults in the United States, 60 percent interpreted "natural" to mean GMO-free.

And yet nearly all the "natural" samples tested contained significant amounts of GMOs.

Labeling Wars

Consumer Reports' policy group, Consumers Union, supports the labeling of products containing GMOs.

The food industry argues there is no point in stigmatizing something that hasn't been proven harmful, while labeling advocates rebut that GMOs haven't been proven completely safe, either.

Voters in Colorado and Oregon will take to the ballot this fall to determine if their states should label GMO-containing products.

Labeling mandates, however, lack consistency. Colorado's proposal includes an exemption that would allow meat from cows raised on GMO products to not be labeled.

But genetically modified sugar beets, once turned into sugar, would bear the GMO label, even though the DNA in the product would no longer contain GMOs, sugar farmer Paul Schlagel points out.

State efforts aren't likely to generate the needed push to get products containing GMOs labeled, but "substantial government interest" is needed, says University of Denver's Justin Marceau.

Read More:

• Where GMOs hide in your food (Consumer Reports)
• U.S. foods labeled 'natural' often contain GMOs, group reports (Reuters)
• Voters Will Get Their Say On GMO Labelilng In Colorado And Oregon (NPR)