Coloring: Colas, baked goods, pre-cooked meats, soy and Worcestershire sauces, chocolate-flavored products, beer.
Caramel coloring is made by heating a sugar compound (usually high-dextrose corn syrup), often together with ammonium compounds, acids, or alkalis. It is the most widely used (by weight) coloring added to foods and beverages, with hues ranging from tannish-yellow to black, depending on the concentration and the food. Caramel coloring may be used to simulate the appearance of cocoa in baked goods, make meats and gravies look more attractive, and darken soft drinks and beer.
Caramel coloring, when produced with ammonia, contains contaminants, 2-methylimidazole and 4-methylimidazole. In 2007, studies by the U.S. National Toxicology Program found that those two contaminants cause cancer in male and female mice and possibly in female rats. In 2011, the International Agency for Research on Cancer, a division of the World Health Organization, concluded that 2- and 4-methylimidazole are "possibly carcinogenic to humans." Then, the State of California's Environmental Protection Agency listed ammonia-caramel coloring as a carcinogen under the state's Proposition 65. The state lists chemicals when they pose a lifetime risk of at least 1 cancer per 100,000 people. California warned that as of January 7, 2012, widely consumed products, such as soft drinks, that contained more than 29 micrograms of 4-methylimidazole per serving would have to bear a warning notice. In March 2012, when CSPI published the results of a study that found levels up to 150 micrograms per can of Coca-Cola and Pepsi-Cola purchased in Washington, DC, the soft-drink giants announced that they had reduced the contaminant to below California's threshold for action in products distributed in California. They said they would market the less-contaminated products throughout the country, which Coca-Cola did in 2013 and PepsiCo did by 2015.
The FDA has a limit that is 10 times as strict as California's for regulating chemicals that are contaminated with cancer-causing chemicals. CSPI's analysis of a Coca-Cola purchased in 2012 in California found just 4 micrograms of 4-MI per 12 ounces. Even that much lower level might exceed the FDA's threshold for action of 1 cancer per million consumers.
It would be worth avoiding or drinking less colas and other ammonia-caramel-colored beverages not only because of risk from the 4-methylimidazole, but, of course, because the products contain about 10 teaspoons of sugar per 12 ounces and promote obesity and tooth decay. Soy sauces, baked goods, and other foods that contain ammoniated caramel coloring are much less of a problem, because the amounts consumed are small.