Starbucks Corp and other coffee sellers must put a cancer warning on coffee sold in California, a Los Angeles judge has ruled, possibly exposing the companies to millions of dollars in fines.

A little-known not-for-profit group sued some 90 coffee retailers, including Starbucks, on grounds they were violating a California law requiring companies to warn consumers of chemicals in their products that could cause cancer.

One of those chemicals is acrylamide, a byproduct of roasting coffee beans that is present in high levels in brewed coffee.

Los Angeles Superior Court Judge Elihu Berle said in a decision dated Wednesday that Starbucks and other companies had failed to show there was no significant risk from a carcinogen produced in the coffee roasting process, court documents showed.

Starbucks and other defendants have until April 10 to file objections to the decision.

Starbucks declined to comment, referring reporters to a statement by the National Coffee Association (NCA) that said the industry was considering an appeal and further legal actions.

"Cancer warning labels on coffee would be misleading. The U.S. government's own Dietary Guidelines state that coffee can be part of a healthy lifestyle," the NCA statement said.

In his decision, Berle said: "Defendants failed to satisfy their burden of proving by a preponderance of evidence that consumption of coffee confers a benefit to human health."

Officials from Dunkin' Donuts, McDonald's Corp , Peet's and other big coffee sellers did not immediately respond to requests for comment.

The lawsuit was filed in 2010 by the Council for Education and Research on Toxics (CERT). It calls for fines as large as $2,500 per person for every exposure to the chemical since 2002 at the defendants' shops in California. Any civil penalties, which will be decided in a third phase of the trial, could be huge in California, which has a population of nearly 40 million.

CERT's lawyer Raphael Metzger did not immediately respond to a request for comment.

Starbucks lost the first phase of the trial in which it failed to show the level of acrylamide in coffee was below that which would pose a significant risk of cancer. In the second phase of the trial, defendants failed to prove there was an acceptable "alternative" risk level for the carcinogen, court documents showed.

Several defendants in the case settled before Wednesday's decision, agreeing to post signage about the cancer-linked chemical and pay millions in fines, according to published reports.

The suit was brought against coffee sellers under a controversial law passed by California voters in 1986 that has been credited with culling cancer-causing chemicals from myriad products and also criticized for leading to quick settlement shakedowns.

The Safe Drinking Water and Toxic Enforcement Act, better known as Proposition 65, requires warning labels for about 900 chemicals known to cause cancer or birth defects. It allows private citizens, advocacy groups and attorneys to sue on behalf of the state and collect a portion of civil penalties for failure to provide warnings.

Scientific evidence on coffee has gone back and forth for a long time, but concerns have eased recently about possible dangers of coffee, with some studies finding health benefits.

In 2016, the cancer agency of the World Health Organization moved coffee off its "possible carcinogen" list.

Studies indicate coffee is unlikely to cause breast, prostate or pancreatic cancer, and it seems to lower the risks for liver and uterine cancers, the agency said. Evidence is inadequate to determine its effect on dozens of other cancer types.

Coffee companies have said it's not feasible to remove acrylamide from their product without ruining the flavor.

But attorney Raphael Metzger, who brought the lawsuit and drinks a few cups of coffee a day, said the industry could remove the chemical without impairing taste.

"I firmly believe if the potato chip industry can do it, so can the coffee industry," Metzger said. "A warning won't be that effective because it's an addictive product."

Many coffee shops have already posted warnings that say acrylamide is cancer-causing chemical found in coffee. But signs that are supposed to be posted at the point of sale are often found in places not easily visible, such as below the counter where cream and sugar are available.

Customers at shops that post warnings are often unaware or unconcerned about them.

Afternoon coffee drinkers at a Los Angeles Starbucks said they might look into the warning or give coffee drinking a second thought after the ruling, but the cup of joe was likely to win out.

"I just don't think it would stop me," said Jen Bitterman, a digital marketing technologist. "I love the taste, I love the ritual, I love the high, the energy, and I think I'm addicted to it."

Darlington Ibekwe, a lawyer in Los Angeles, said a cancer warning would be annoying but wouldn't stop him from treating himself to three lattes a week.

"It's like cigarettes. Like, damn, now I've got to see this?" he said. "Dude, I'm enjoying my coffee."

California's outsized market could make it difficult to tailor packaging with warning labels specifically to stores in the state.

That means out-of-state coffee drinkers could also take their coffee with a cancer warning. Cream and sugar would still be optional.