Summary: The US Food and Drug Administration lists artificial food coloring as safe for human consumption but several studies have indicated that this may not be the case. One consumer group raises very real concerns about food dye additives, which merit further consideration.
The US Food and Drug Administration lists artificial food coloring as safe.
More Info: If added to foods, drugs, or cosmetics, artificial food coloring is regulated and approved as safe by the US Food and Drug Administration. But there are several reputable studies that suggest that this may not be the case.
What Is Artificial Food Coloring?
Unlike natural food colorings that come from nature, artificial food coloring is synthetic. Manufacturers prefer to use synthetic food coloring because it is cheaper to use than natural color additives, preserves the quality of color better, and is uniform and intense in color. The FDA certifies artificial food coloring and has approved nine color additives for use in the United States. You can view a list of all FDA approved color additives
How the FDA Labels Food Coloring
When you see the letters “FD&C” on a label, it means that the food coloring or dye is approved by the US Food and Drug Administration for use in Foods, Drugs and Cosmetics. D&C would therefore only be approved for use in Drugs and Cosmetics. 
Why the Controversy?
It should be noted that there has been considerable controversy over the synthetic food-coloring agents used to color the foods we eat, the prescription and over-the-counter oral and topical medications we use, and the myriad of cosmetics and soaps on the market. A handful of studies analyzing the safety of consuming artificial food coloring have raised concerns with consumer groups. For example, according the Center for Science in the Public Interest (CSPI), one such study that tested the color additive yellow-5 indicated that in animal testing it caused tumors of the kidney and adrenal gland. The FDA reviewed the findings and concluded that the additive does not pose a significant health risk to humans. These studies and the subsequent overturning of findings are at the center of the artificial coloring controversy. 
The CSPI petitioned the FDA in 2008 to ban the use of artificial food dyes based on 20 controlled studies that assessed food dye additives and concluded that much of the evidence suggested the even modest doses of dyes adversely affects the behavior in some children. This is alarming news as many of the dyes in use today, target children by brightly coloring their snacks, cereals, and beverages. Artificial food dyes are currently not tested for developmental neurotoxicity. 
The executive director of CSPI also points out in his published article in the journal Environmental Health Perspectives that many of the rodent studies measuring evidence of carcinogenicity run for two years. He argues that new evidence supports the fact that cancers may not actually show up until a rodent’s third year, which may reduce the likelihood of a positive result. 
 “Food Ingredients and Colors.” U S Food and Drug Administration Home Page. N.p., n.d. Web. 1 Aug. 2012. < http://www.fda.gov/food/foodingredientspackaging/ucm094211.htm>
 “Food Additives ~ CSPI’s Food Safety.” Center for Science in the Public Interest. N.p., n.d. Web. 10 Aug. 2010. http://www.cspinet.org/reports/chemcuisine.htm.
 Potera, Carol. “IET AND NUTRITION: The Artificial Food Dye Blues.” Environmental Health Perspective 118, no. 10 (2010): 428.
 Huff, J. “The Limits of Two-year Bioassay Exposure Regimens for Identifying Chemical Carcinogens.” Environmental Health Perspective 116, no. 11 (2008): 1439-42.