Coca-Cola and Pepsi are changing the recipes for their drinks to avoid putting a cancer warning label on the bottle, to comply with California laws.

根据加州法律，可口可乐和百事可乐将改变饮料生产配方以避免瓶子被打上癌症警示标志。

The new recipe for the drinks' caramel（焦糖） colouring will have less 4-methylimidazole（甲基咪唑） , a chemical California has added to its list of carcinogens.

The change to the recipe has already been introduced in California.

But the companies say rolling out the new recipe across the US makes the drinks more efficient to manufacture.

"While we believe that there is no public health risk that justifies¹ any such change, we did ask our caramel suppliers to take this step so that our products would not be subject to the requirement of a scientifically unfounded warning," Coca-Cola representative Diana Garza-Ciarlante told the Associated Press news agency.

The chemical has been linked to cancer in mice and rats, according to one study, but there is no evidence that it poses a health risk to humans, said the American Beverage² Association, which represents the wider industry.

The US Food and Drug Administration claims a person would need to drink 1,000 cans of Coke or Pepsi to take in the same dose of the chemical that was given to the animals in the lab test.

Coca-Cola and PepsiCo account for nearly 90% of the fizzy drink（汽水） market, according to one industry tracker, Beverage Digest.