A California appellate court has sided with the makers of 59 brands of breakfast cereal in finding that federal law pre-empts a lawsuit attempting to force them to warn customers the cereals contain acrylamide, a chemical on the state’s list of known causes of cancer and reproductive problems.

Acrylamide, which has been produced artificially since the 1950s for various industrial purposes and occurs naturally when carbohydrate-rich foods are prepared certain ways, was added to California’s list of chemicals known to cause cancer in 1990. Under California’s Proposition 65, products containing chemicals on the list must include warning labels.