Coca-Cola said Friday it will lower levels of a chemical in caramel coloring to comply with a California law, but insisted the beverage's recipe will not change and poses no health risks.

Pepsi is making similar changes in order to avoid having to label products with a cancer warning due to what California has ruled are high levels of 4-methylimidazole (4-MEI), shown to cause cancer in lab animals, consumer advocates said.

The changes do not amount to a change to Coke's formula, spokesman Ben Sheidler told AFP.

"We are NOT changing our recipe; or our formula," he said in an email.

"What we did do is direct our caramel suppliers to make a manufacturing process modification in order to reduce the level of 4-MEI in our caramel so as to meet the requirement set by the State of California's Proposition 65."

California voters passed Proposition 65 in 1986, and the law aims to protect state residents from "chemicals known to cause cancer, birth defects or other reproductive harm, and to inform citizens about exposures to such chemicals."

California has a 29-microgram benchmark for 4-MEI. According to the Center for Science in the Public Interest, a recent sampling of Coke and Pepsi drink cans in the Washington area showed levels ranging between 103 mcg and 153 mcg.

But beverage industry leaders including the American Beverage Association (ABA) argued the evidence of a cancer link is limited to one study in mice and is not recognized by major US, European and Canadian health agencies.

The ABA added that a person would need to drink massive amounts of cola to reach a risk level similar to the dosing in mice -- 2,900 cans of cola every day for 70 years -- upon which California based its decision.

"The science simply does not show that 4-MEI in foods or beverages is a threat to human health," the ABA said.

"In fact, findings of regulatory agencies worldwide, including the US Food and Drug Administration, European Food Safety Authority and Health Canada, consider caramel coloring safe for use in foods and beverages."

Executive director Michael Jacobson of the consumer group Center for Science in the Public Interest, applauded the move, saying the caramel coloring chemical levels would be cut by 90 percent.

"The question is, when will Coke and Pepsi make these changes around the world, not just in California?" he said.

Sheidler said Coca-Cola would begin enacting the same changes to beverages nationwide and globally "in order to streamline and simplify our supply chain, manufacturing, and distribution systems," though no timeline has been set.