A state judge on Wednesday ruled that California law requires coffee companies, which include Starbucks, to carry a cancer warning label due to a chemical produced in the roasting process.

Proposition 65

Proposition 65, also called the Safe Drinking Water and Toxic Enforcement Act, requires businesses in California to notify consumers about the significant amounts of chemicals present in products that are in homes or workplaces or that are released into the environment, with the objective of enabling Californians to make informed decisions that could protect themselves from being exposed to potentially dangerous chemicals.

One of the chemicals covered by this state law is acrylamide present in coffee.

The nonprofit group Council for Education and Research on Toxics sued Starbucks and about 90 other companies under this California law, but the coffee industry said that the amount of acrylamide is at a harmless levels.

Acrylamide

Coffee companies said that removing acrylamide from their product could ruin the coffee's flavor, but the chemical isn't just found in coffee. It is also present in cigarette smoke and other types of cooked food.

It forms when foods, especially starchy ones such as coffee beans, potato chips, french fries, and breakfast cereals are heated to high temperatures.

Once acrylamide is in the body, it is converted into glycidamide, which can cause mutations and damage to the DNA. The National Cancer Institute says that while exposure to acrylamide has been shown to increase the risk of cancer in rodents, there is less evidence the chemical causes the same effect on humans.

"A large number of epidemiologic studies (both case-control and cohort studies) in humans have found no consistent evidence that dietary acrylamide exposure is associated with the risk of any type of cancer," the NCI said. "One reason for the inconsistent findings from human studies may be the difficulty in determining a person's acrylamide intake based on their reported diet."

Coffee Companies Failed To Prove Threat From Acrylamide Is Insignificant

The coffee industry argued that acrylamide should be exempted from the law since it is produced naturally from the cooking processes needed to make coffee beans flavorful.

Superior Court Judge Elihu Berle, however, wrote in a proposed ruling that coffee companies failed to show that the threat from this chemical was insignificant.

"Defendants failed to satisfy their burden of proving ... that consumption of coffee confers a benefit to human health," Berle wrote in his proposed ruling.