A Vermont law mandating the labeling of food with genetically modified ingredients goes into effect in a few months, and both sides of the issue say it inadvertently could become the nationwide standard.

The law goes into effect on July 1 and requires all products sold in the state that contain genetically modified organisms to be labeled as such. The law is prompting some major food producers such as Kellogg, General Mills and Mars to re-label all of their products, not just those going to Vermont, to save costs.

'The supply chain simply doesn't allow them to create a Vermont-only supply chain.'

Congress has tried to pass legislation pre-empting the state law, but the efforts have stalled.

The law was created as part of a grassroots effort from citizens "who simply wanted to make an informed choice about the food they purchase," said Katherine Webb, a state lawmaker who sponsored the legislation.

Webb said Vermont residents were concerned about the increased use of certain herbicides and seed trespass, when genetically engineered seeds can contaminate organic crops.

The safety of GMO foods is hotly debated. They are created to increase resistance against diseases and insects or to give greater tolerance for herbicides, according to the World Health Organization.

The WHO said that current GMO foods on the market passed safety tests and "aren't likely to present" risks for human health.

The Food and Drug Administration also has said that GMO plants are safe to eat. The agency has approved the marketing of genetically engineered salmon.

While the Vermont law affects only products sold in the state, it has already created a lasting impact on the debate over GMO labeling.

Major food industries are fighting the labeling law, saying that producers will have to have a GMO label for all of their products nationwide.

"We are noticing that a lot of manufacturers are putting the Vermont-mandated label on their packages nationwide," said Mike Gruber, senior vice president for federal affairs with the Grocery Manufacturers Association. "The supply chain simply doesn't allow them to create a Vermont-only supply chain. The Vermont mandate has become the national mandate for our industry."

Case in point is General Mills, which announced last month it would start labeling GMOs nationwide due to the Vermont law.

"We can't label our products for only one state without significantly driving up costs for our consumers, and we simply will not do that," the cereal manufacturer said in a statement on its website.

Gruber said the cost for producers has been "tremendous," as thousands of products had to be re-labeled, but didn't provide an exact figure.

The grocer association lobbied for legislation in the House and Senate that would pre-empt state GMO laws such as Vermont from going into effect.

Vermont isn't the only concern for grocers and producers, as California and other states are considering similar GMO laws. The association is concerned that different states will enact laws with different labeling requirements.

Maine and Rhode Island have passed GMO labeling laws, and more than 10 states have proposed such laws, according to the Center for Food Safety, a nonprofit that advocates for GMO labeling.

The federal bill passed the House, but stalled in the Senate due to a Democratic filibuster.

About five manufacturing associations such as the grocers and the Snack Foods Association are suing Vermont to overturn the law, arguing that the power over labeling belongs with the federal government, Webb said.

"If this is so clear, why is everyone trying to pass a law that the five manufacturing groups say already exists?" she told the Washington Examiner.

Webb said Vermont would prefer a national solution.

"You shouldn't have to live in Vermont to know how your food was produced," she told the Washington Examiner. "Vermont and other states have simply grown weary waiting for Congress to act on this simple right to know."