Specifically, the soda giants are reducing the amount of 4-methylimidazole in their caramel coloring – a chemical that's been added to California's list of carcinogens.
While one study has linked the chemical to cancer in mice and rats, the American Beverage Association, which represents the broader beverage industry, said there was no evidence to suggest humans were at risk, the BBC reported.
Coca-Cola representative Diana Garza-Ciarlante told the AP her company did not feel that Coke, in its original formula, posed a public health risk.
"We asked our caramel suppliers to take this step so that our products would not be subject to the requirement of a scientifically unfounded warning."
According to the Food and Drug Administration, a consumer would have to drink more than 1,000 cans of soda a day to ingest the same dose of the chemical that was given the the rodents in the lab test, the Australian Associated Press reported.
It is estimated that Coke and Pepsi account for nearly 90 percent of the soda market.
The change to their recipes has already been introduced in California, and is to be expanded throughout the US, to streamline manufacturing.