Caramel coloring can contain two contaminants, 2-methylimidazole (2-mel) and 4-methylimidazole (4-mel), that have been linked to cancer in mice and is classified as “possibly carcinogenic to humans.” California’s Environmental Protection Agency listed ammonia-caramel coloring as a carcinogen, requiring warning notices on products with over 29 micrograms of 4-methylimidazole per serving. Following a study revealing high levels in Coca-Cola and Pepsi-Cola, the companies reduced the contaminant and introduced less-contaminated versions nationwide by 2015. Levels of these possible carcinogens may be much lower in food and beverage manufacturing today, however, high consumption of soft drinks could result in higher than safe intakes of these compounds, and many of the foods using caramel coloring are highly processed that may have other adverse effects on health.