NEW YORK ( MainStreet) — That soft drink in your hand may be doing more damage than you realize.. A new study by Consumer Reports reveals a potentially-carcinogenic chemical byproduct might be lurking in caramel colored colas.

The tests found varying levels of 4-methylimidazole (4-MeI), particularly in beverages that listed "caramel color" as an ingredient. Twelve brands of sodas and soft drinks were tested from five manufacturers – including Coca-Cola, Pepsi, and Goya.

"We are concerned about both the levels of 4-MeI we found in many of the soft drinks tested and the variations observed among brands, especially given the widespread consumption of these types of beverages," says Dr. Urvashi Rangan, a toxicologist and executive director of the Consumer Reports Food Safety and Sustainability Center. "There is no reason why consumers need to be exposed to this avoidable and unnecessary risk that can stem from coloring food and beverages brown."

The non-profit consumer advocacy notes that caramel color is used in certain food and beverages as a coloring agent and should not be confused with real caramel.

"Some types of this artificial coloring contain 4-MeI which has been recognized as a possible human carcinogen by the International Agency for Research on Cancer," the report says.

There are currently no federal limits imposed on the amount of caramel color allowed in food and beverages; however, products sold in California that would expose consumers to more than 29 micrograms of 4-MeI in a day are required to carry a warning label under the state's Proposition 65 law.

Consumer Reports tested cans and bottles of popular brands of soft drinks and found that 12-ounce single servings of two products in particular, purchased multiple times during an eight-month period in the state of California – Pepsi One and Malta Goya – exceeded the state's 4-Mel limit.

"While we cannot say that this violates California's Prop 65, we believe that these levels are too high, and we have asked the California Attorney General to investigate," Consumer Reports said in a statement.

PepsiCo issued a statement saying Proposition 65 is based on per-day exposure and not exposure per can. The company also cited government consumption data that shows that the average amount of diet soda consumed by people who drink it is 100 milliliters per day, or less than a third of a 12-ounce can. For that reason, they believe that Pepsi One does not require cancer-risk warning labels – even if the amount of 4-MeI in a single can exceeds 29 micrograms.

"While our study is not big enough to recommend one brand over another, our results underscore two key points," Rangan said. "The first is that it is indeed feasible to get down to lower and almost negligible levels of 4-MeI. And the second is that federal standards are required to compel manufacturers to minimize the creation of this potential carcinogen."