According to the U.S. Food and Drug Administration (FDA), 4-methylimidazole (4-MEI) is a trace impurity formed during the manufacturing of certain types of caramel coloring, particularly those used to color cola beverages and other foods.  The FDA noted on its website that, as of 2013, the available evidence gave the FDA no reason to believe that there is any short-term or immediate harm from the 4-MEI levels expected in food.

However, TIME Health & Family reports that the FDA is conducting new studies of the safety of caramel coloring in soft drinks and other foods, even though previous research has shown no identifiable health risk.  While the FDA has stated that it has studied caramel coloring for decades as both a flavor and a color additive, without any indication of harm.  Now, it is reviewing new data on the 4-MEI often found in caramel coloring, but the FDA has not given any information as to the nature of the data.

The FDA efforts come on the heels of recent Consumer Reports evidence about the levels of caramel coloring and 4-MEI in sodas.  Consumer Reports sought to look into the current situation given the uncertain regulatory environment.  In 2007, a federal government study concluded that 4-MEI caused cancer in mice and the International Agency for Research on Cancer (IARC) determined the chemical to be a possible human carcinogen in 2011.  PepsiCo spokeswoman Aurora Gonzalez said the company is extremely concerned about the study and believes it is factually incorrect.

While, there is currently no federal limit for levels of 4-MEI in foods and beverages, California requires a cancer warning label on any products that exceed a certain level of 4-MEI.  Consumer Reports discovered that the 4-MEI levels in popular soft drinks were drastically different between California and other states.  Specifically, for Pepsi, Diet Pepsi, and Pepsi One, the levels in New York were five or more times higher than for the same beverages in California.

These findings are particularly alarming.  According to a Gallup Poll, approximately 48 percent of Americans drink soda every day.  That number has remained relatively consistent since 1999.  Among soda drinkers, the average daily amount is 2.6 glasses, with 7 percent drinking four or more glasses every day.  Of those that drink soda, the majority drink one glass per day.  The sugary drink can contribute to obesity, diabetes, and other health problems. Health experts say even one glass of sugary soda per day is too much.