Hadley Malcolm

USA TODAY

General Mills said Friday that it will start labeling its products that contain genetically modified ingredients in response to a law going into effect in Vermont later this year.

The maker of Cheerios, Yoplait and Betty Crocker joins Campbell Soup as one of the few major consumer product companies to adopt labeling amid a contentious debate in Congress about whether identifying GMOs — genetically modified organisms — should be voluntary.

In a blog post, General Mills argued for a national standard for GMO labeling but said that in the meantime, the company will start labeling certain products that contain GMOs. The decision comes as General Mills and other food producers prepare to comply with a Vermont law that will require GMOs to be identified starting July 1. General Mills said that it's more cost effective to adopt the practice across the country in order to keep prices from rising for customers.

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The labels will start hitting grocery stores over the next several weeks and customers can expect thousands of packages to be updated with new language, says General Mills spokesman Mike Siemienas.

General Mills also launched a tool that lets customers search for products that contain GMOs, which includes Betty Crocker frosting, Chex cereal and Nature Valley bars.

"We know that some consumers are interested in knowing which products contain GMO ingredients," said Jeff Harmening, chief operating officer for U.S. retail at General Mills.

The fight over GMO labeling has been fraught with the question of whether GMOs are safe to consume. Some advocacy groups say there hasn't been sufficient testing to determine whether GMOs pose a health risk. Genetically engineered foods, like corn and soybeans, have been part of the U.S. food supply since the 1990s and the Food and Drug Administration says they are safe to eat. In the blog post, Harmening reiterates General Mills' position that GMOs are safe.

General Mills owns several brands whose products don't contain GMOs, such as Annie's, Cascadian Farm and Larabar.