Coca-Cola and Pepsi are changing the way an ingredient in their world-famous soft drinks is made to avoid being legally obliged to put a cancer warning label on their bottles.

The change comes after the state of California added the chemical 4-methylimidazole, used in the caramel colouring of both drinks, to its list of carcinogens.

Both the American Beverage Association and the US Food and Drug Administration say there is no evidence the chemical poses a health risk to humans.

Tom Esslemont reports.