Coca-Cola and Pepsi have changed the ingredients in their US soft drinks to avoid having to put a cancer warning on packs.

In order to comply with new standards introduced in California the companies have asked suppliers of caramel colourings to reduce the level of chemical 4-methylimidazole, which can be found in trace amounts in many foods.

The changes are being made to drinks sold across the US but are not set to be introduced in the UK or Europe.