Get breaking news alerts and special reports. The news and stories that matter, delivered weekday mornings.

President Obama has signed a new law that would require all food labels to declare for the first time whether the item contains genetically modified ingredients.

Just how clear those labels are, however, is up for debate.

The new law, signed Friday and supported by the food industry, pre-empts a recently passed — and stricter — Vermont ruling that requires food to say "produced with genetic engineering." Instead, companies will be allowed to either say that in plain words on the package, or provide a QR code, 1-800 number, or website for consumers to visit for more information.

Milk is displayed on shelves in a Brooklyn supermarket on June 9 in New York City. Milk prices for Americans have been on the rise recently with a 7.5% price increase for a gallon of fortified whole milk from last year. Spencer Platt / Getty Images

Opponents argue that this type of labeling discriminates against lower-income families who may not have access to the technology required to learn further details.

Plus — when you've got a grabbing toddler in the stroller and you're snagging crates of mac n' cheese off the shelves, you probably won't have time to be scanning bar codes.

A recent review of two decades of research and over 900 studies by the National Academy of Sciences has not found any evidence that genetically modified organisms pose a hazard to human health. But advocates say not enough is known about GMOs — and consumers want to know exactly what's in their food.