The Center for Science in the Public Interest said that samples of Coca-Cola tested in nine countries showed "alarming amounts" of the chemical 4-methylimidazole, or 4-MI, used as an ingredient in caramel coloring. High levels of that chemical have been linked to cancer in animals.

In March, both Coca-Cola and rival PepsiCo Inc said that they had asked suppliers of the caramel coloring to alter their manufacturing process to meet the requirements of a California ballot initiative aiming to limit people's exposure to toxic chemicals.

Coca-Cola said at the time that it would start in California and expand the use of the reduced 4-MI caramel coloring over time. It did not specify a timetable.

Coca-Cola repeated on Tuesday that the caramel coloring in all of its products was safe and that it had asked suppliers to change their manufacturing process to comply with California's labeling requirement.

According to CSPI, sample bottles from California tested this spring showed only 4 micrograms of 4-MI per 12 ounces. California requires a warning label if a food would lead to people consuming 30 micrograms or more a day.

But samples from Brazil contained 267 micrograms and samples from Kenya had 177 micrograms, CSPI said. Even in the United States, samples from Washington D.C. had 145 micrograms.

CSPI Executive Director Michael Jacobson said consumers in some other countries drink much less soda than those in the United States, so they have less exposure to the chemical.

"But now that we know it's possible to almost totally eliminate this carcinogen from colas, there's no excuse for Coca-Cola and other companies not to do so worldwide, and not just in California," he said in a statement.

The U.S. Food and Drug Administration is considering a petition by the watchdog group to ban the process that creates the heightened 4-MI levels, but said that there is no reason to believe there is any immediate or short-term danger to consumers.

Earlier this year, an FDA spokesman said a person would have to drink "well over a thousand cans of soda a day to reach the doses administered in the studies that have shown links to cancer in rodents".

Coca-Cola said on Tuesday it was still working on the logistics of introducing the new caramel coloring.

"We intend to expand the use of the modified caramel globally to allow us to streamline and simplify our supply chain, manufacturing, and distribution systems," the company said in a statement.

A spokeswoman declined to say how much the switch would cost.

(Reporting By Brad Dorfman; Editing by Tim Dobbyn)

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