LOS ANGELES, April 1 (Xinhua) -- Los Angeles Superior Court in the western U.S. state of California has judged that coffee companies should label their coffee products sold in California with cancer warnings, which aroused much controversy.

The judgment was proposed by judge Elihu Berle, who said the companies failed to "satisfy their burden of proving ... that consumption of coffee confers a benefit to human health."

"While plaintiff offered evidence that consumption of coffee increases the risk of harm to the fetus, to infants, to children and to adults, defendants' medical and epidemiology experts testified that they had no opinion on causation," Berle said Wednesday as quoted by the Associated Press.

The lawsuit was filed by a U.S. nonprofit group, the Council for Education and Research on Toxics (CERT), arguing that sellers in California should notify customers of the acrylamide hazard in coffee.

Coffee companies, led by Starbucks Corp., claimed that the presence of the chemical in coffee is at trace levels that are harmless.

California passed the Safe Drinking Water and Toxic Enforcement Act, also known as Proposition 65, in 1986 requiring warnings on consumer products for toxic substances that may cause cancer and birth defects.

Acrylamide is a chemical that can form in some foods during high-temperature cooking and has been found to be carcinogenic in rodents. In coffee's case, the hazard could be generated when roasting coffee beans.

A similar suit was filed in 2002 to the Los Angeles County Superior Court by the CERT against McDonald's and Burger King.

The case settled after six years as the two fast food companies agreed to provide cancer hazard warnings regarding acrylamide in their french fries sold in California.

Concerns about possible dangers of coffee reemerged after the ruling on acrylamide in coffee, while many argued that studies suggested drinking coffee is safe or even decreases cancer risks.

In a 2016 study done by the World Health Organization's cancer research agency, no conclusive evidence was found that coffee causes cancer.