Coca Cola and Pepsi are changing their drinks recipes because the state of California is listing a key ingredient as potentially cancerous. The soft drinks giants stress there are no health concerns. They say they just do not want to fall foul of what they describe as a "scientifically unfounded warning."
Coca-Cola has denied reports that it is changing its drinks formula because of health concerns over an ingredient in the US.
Like its rival Pepsi, it is making changes to the production of a caramel colouring - beginning in California where a chemical ingredient, 4-MEI, has been added to a list linked to cancer.
A US watchdog, the Center for Science in the Public Interest, has told the consumer protection agency the Food and Drug Administration that it found unsafe levels of the chemical in various colas.
"Even the amount of 4-methylimidazole that remains in California colas exceeds the amount that the FDA considers acceptable. We've urged the FDA to take action and get this caramel colouring off the market," said Michael Jacobson, the CSPI's Executive Director.
The FDA said last week that it was reviewing the group's petition.
It has described the colas as safe, saying people would need to drink 1,000 cans a day to absorb doses of the chemical that have shown links to cancer in mice and rats.
"There is no link to cancer in humans. The dose consumed each day is extremely small, so that's why there's no risk," said French scientist Jean-François Narbonne, Professor of Toxicology at Bordeaux University.
By reducing the amount of 4-MEI in the colouring, manufacturers will avoid having to add health warnings in California.
Coca Cola and Pepsi say their products remain safe and consumers will notice no difference.