March 30 (UPI) -- A California judge's ruling has given coffee consumers a major jolt, by demanding every cup of joe be labeled with a cancer warning. But the research behind the cancer risk of drinking coffee is not too strong.
Although roasted coffee beans contain a carcinogen -- acrylamide -- it's unclear whether the levels are high enough to pose a health risk to humans, according to previous medical studies.
And if acrylamide causes cancer, it also would affect overly cooked or roasted starchy foods.
The Grocery Manufacturers Association said acrylamide is found in 40 percent of the calories consumed in the average U.S. diet, including coffee beans, french fries, potato chips, breakfast cereals and toast.
It's also found in cigarette smoke.
It wasn't until 2002 that scientists discovered the chemical in food.
Acrylamide forms from sugars and an amino acid that are naturally present in food.
The IARC, which is part of the World Health Organization of the United Nations, listed it as a possible carcinogen in 2015 because of its link to cancer in rodents.
But one year later it rescinded the warning after it asked 23 researchers to review more than 1,000 studies in humans and animals on consumption of coffee, finding "inadequate evidence" that drinking coffee is carcinogenic.
In the review, which was published in The Lancet, researchers found no evidence coffee has carcinogenic effects on pancreas, female breast, bladder or prostate cancer, and that "reduced risks" were seen for cancers of the liver and uterine endometrium. The evidence was considered inconclusive for more than 20 other cancers.
On March 1, 2016, the FDA posted a final document to help growers, manufacturers and food service operators lower the amount of acrylamide in foods associated with higher levels of the chemical.
"Generally speaking, acrylamide is more likely to accumulate when cooking is done for longer periods or at higher temperatures," FDA chemist Lauren Robin said.
She said boiling and steaming foods do not typically form acrylamide.
Robin also said it's not feasible to completely eliminate acrylamide from a diet. She said removing any one or two foods from your diet would not have a significant effect on overall exposure to acrylamide.
Berle temporarily supported a lawsuit against several large companies, including Starbucks, Whole Foods, 7-11 and others for serving coffee with the chemical.
The ruling is based on California's Proposition 65, which requires businesses to warn customers if a product contains a chemical linked to cancer. That includes acrylamide.