It's the most common coloring in foods and drinks—and it can contain a potential carcinogen. Here's what Consumer Reports found when it tested soft drinks that have caramel color.

Caramel color, added to many soft drinks and some foods to turn them brown, may sound harmless, even appetizing. But in no way does it resemble real caramel. Some types of this artificial coloring contain a potentially carcinogenic chemical called 4-methylimidazole (4-MeI). Under California's Proposition 65 law, any food or beverage sold in the state that exposes consumers to more than 29 micrograms of 4-MeI per day is supposed to carry a health-warning label. In recent Consumer Reports' tests, each of the 12-ounce samples of Pepsi One and Malta Goya had more than 29 micrograms per can or bottle. While we cannot say that this violates California's Prop 65, we believe that these levels are too high, and we have asked the California Attorney General to investigate.

Caramel color is the single most used food coloring in the world, according to a 2013 report from market research firms Mintel and Leatherhead Food Research. "There's no reason why consumers should be exposed to an avoidable and unnecessary risk that can stem from coloring food brown," says Urvashi Rangan, Ph.D., toxicologist and executive director of Consumer Reports' Food Safety & Sustainability Center. "Manufacturers have lower 4-MeI alternatives available to them. Ideally there would be no 4-MeI in food."

READ MORE: Caramel color: The health risk that may be in your soda