The caramel coloring used in PepsiCo Inc. drinks contains high levels of a probable carcinogen, according to a new study by the watchdog group The Center for Environmental Health (CEH). Pepsi had claimed to have removed the chemical, but the CEH reports otherwise.

In order to avoid a cancer warning label in California, Pepsi and Coca-Cola Co.—which together account for almost 90 percent of the soda market according to industry tracker Beverage Digest—both reportedly adjusted their formulas across the U.S. in March in order to disclude the chemical called 4-methylimidazole or 4-Mel. The chemical was linked to cancer in mice and rats.

CEH commissioned Eurofins Analystical laboratory in Metairie, Louisiana to test Coke and Pepsi products from California in May and from across the country in June. The result, ccording to CEH, was that Coke products no longer test positive for 4-Mel but Pepsi products outside of California still do.

According to Huffington Post, Pepsi says its suppliers are still transitioning the manufacturing process to cut the amount of 4-Mel in its caramel, but the process won't be complete until Feb. 2014 outside of California. Pepsi also said it will remove 4-Mel worldwide, but did not provide a timeline.

Pepsi claims that the 4-Mel chemical is safe, noting that the FDA and other regulatory agencies have not deemed the chemical unsafe.

According to USA Today, the Food and Drug Administration says a consumer would have to drink more than 1,000 cans of soda a day to reach the doses administered that have shown links to cancer in rodents. But, after a study on mice and rats linked the coloring chemical to cancer, California added 4-Mel to its list of carcinogens.