Caramel coloring is found in many food items you consume, as well as your pet's food. From name brands to generic you will find 'caramel' listed as an ingredient. Traditional caramel, if you were to make it at home, involves melting sugar until it is brown and thickened. 'Caramel' found in your food is a manufactured chemical of sugar with ammonia and sulfites, resulting in 2-methylimidazole and 4 methylimidazole.(1)
Studies have shown that lab mice and/or rats develop cancers from ingesting 4 methylimidazole. Here is a link for one research study published in the Archives of Toxicology. Though:
A consumer would have to consume well over a thousand cans of soda a day
reach the doses administered in the studies that have shown links to cancer
rodents," the FDA tells WebMD. (2)
However, it is not just soda that you find this 'caramel coloring', so I believe that consumers may be ingesting more than they may think. The only way you know if you are ingesting it (but not the amount you are ingesting) is to read your food ingredient labels. Other research indicates that over 15,000 cancers are associated with 4 methylimidazole, though I have not spent that much time locating these studies.
California has listed 4 methylimidazole to the list of known carcinogens resulting in Soda Companies to change the formula for developing this chemical. (3) So the next time you pick up a can of soda you can expect that the caramel coloring has been changed today, but do you still want this chemical in your food? In your pet's food? Do we really need this to add a color to our food? Now that you have some information you can decide for yourself.
(1) FDA Urged to Prohibit Carcinogenic "Caramel Coloring" by The Center for Science in the Public Interest. pub: February 16, 2011. <http://www.cspinet.org/new/201102161.html> Accessed November 1, 2012.
(2) Cancer in Colas' Caramel Coloring?. by Daniel J DeNoon. pub. March 5 2012. WebMD Health News. <http://www.webmd.com/cancer/news/20120305/cancer-in-colas-caramel-coloring> Accessed November 1, 2012.
(3) Coke, Pepsi to change caramel coloring recipes. Associated Press. pub. March 9 2012; FOX News. <http://www.foxnews.com/health/2012/03/09/coke-pepsi-to-change-caramel-coloring-recipes/>. Accessed November 1, 2012.