The latest results of a study comparing the attributes of 11 different soft drinks, as well as analyzing the consumption habits of Americans, have shown that drinking as little as one soda a day could be enough to expose consumers to potentially cancer-causing levels of the chemical 4-methylimidazole, or 4-MEI for short.

The carcinogen is formed as a byproduct of the process that creates the familiar dark caramel color that is added to many popular beverages. A California law has determined that drinks pose an “excess cancer risk” if consuming the product exposes the drinker to more than 29 mcg of 4-MEI every day. The law requires companies to include a warning label on drinks sold in the state that exceed these levels. Other states, however, do not have such precautions in place, and researchers found drinks containing 4-MEI levels that ranged from 9.5 mcg per liter to 963 mcg per liter.

The study was led by a team at the Johns Hopkins Center for a Livable Future in Baltimore, MD. They tested 110 samples of soda brands which revealed widely varied concentrations of 4-MEI. Generally, however, they found that the levels were “consistent across lots of the same beverage purchased in the same state/area.” Some soft drinks in California contained noticeably lower levels of 4-MEI, which led researchers to believe that the state’s required warning labels were effective in reducing cancer risk to consumers.

The study also found that 44 percent of children (ages six and up), and 58 percent of adults consume at least one can of soda per day. This could mean that almost half of the American population is exposing itself to a cancer-causing carcinogen every day.

Senior author of the study, Keeve Nachman, said “Soft drink consumers are being exposed to an avoidable and unnecessary cancer risk from an ingredient that is being added to these beverages simply for aesthetic purposes… This unnecessary exposure poses a threat to public health and raises questions about the continued use of caramel coloring in soda.”

Right now, there is no federal limit on the amount of 4-MEI that can be present in food or drink. “An FDA intervention, such as determining maximum levels for 4-MEI in beverages, could be a valuable approach to reducing excess cancer risk attributable to 4-MEI exposure in the U.S. population,” said Nachman.