Consumer Reports in January published a report on apparently high levels of 4-methylimidazole (4-MEI) in soft drinks in California, apparently in violation of that state's labeling requirements for possible carcinogens. The story got enough airplay that the FDA reaffirmed its ongoing study of 4-MEI and hinted regulatory action would be considered.
Some forms of processing can cause 4-MEI to appear in varying concentrations in caramel color, "the single most used food coloring in the world, according to a 2013 report from market research firms Mintel and Leatherhead Food Research," Consumer Reports noted. It's used to color virtually every cola. In 2007, a federal government study concluded that 4-MEI caused cancer in mice, and the International Agency for Research on Cancer determined the chemical to be “possibly carcinogenic to humans” in 2011.
While there is no federal limit for levels of 4-MEI in foods and beverages, California requires manufacturers to label a product sold in the state with a cancer warning if it exposes consumers to more than 29 micrograms of 4-MEI per day.
In the Consumer Reports’ tests, each of the 12-oz. 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."
The FDA released this statement: “The FDA appreciates the work done by Consumer Reports on the use of caramel coloring in soda. The FDA has studied the use of caramel as a flavor and as a color additive in foods for decades. To ensure that the use of caramel colors in food continues to be safe, the FDA is currently testing a variety of foods, including sodas, for 4-methylimidazole … The agency is also reviewing new data on the safety of 4-MEI. These efforts will inform the FDA’s safety analysis, and will help the agency determine what, if any, regulatory action needs to be taken. Currently, the FDA has no reason to believe that 4-MEI, at the levels expected in food from the use of caramel colors, poses a health risk to consumers.”
Consumer Reports also tested 365 Everyday Value Dr. Snap, A&W Root Beer, Brisk Iced Tea, Coca-Cola, Coke Zero, Diet Coke, Diet Pepsi, Dr Pepper, Pepsi and Sprite (as a control). Tests were performed in both California and New York in two test periods: April-September and again in December of 2013.
Consumer Reports added: "On average, three of the brands — Coke, Diet Coke, and Coke Zero — came in under 5 micrograms per can in our tests, a level Consumer Reports’ experts believe is more acceptable. Sprite, a clear soda that was tested as a control, showed no significant levels of 4-MEI."