A California judge ruled last week that coffee sellers in the state must post warnings about the popular beverage’s cancer risks.
This puts coffee among the ranks of clearly dangerous products such as asbestos and hexavalent chromium. But also alongside food products like alcohol, where cancer risk depends on how much you ingest.
So does coffee warrant this kind of warning label?
Some health experts say the available scientific evidence suggests no. They add that overuse of warning labels may lead some consumers to ignore them.
The lawsuit that led to this ruling centered not on coffee itself but on a chemical, acrylamide, produced when the beans are roasted.
This chemical is also found in high-carbohydrate foods processed at high temperatures, such as potato chips, french fries, cookies, breakfast cereals, and bread.
Tests by the Food and Drug Administration (FDA) show that acrylamide levels in coffee range from below 100 to more than 600 parts per billion.
In comparison, french fries from one fast-food chain contained acrylamide levels between 155 and 497 parts per billion, depending on the location tested. Levels in some other commercial fries exceeded 1,000.
Acrylamide is also found in cigarette smoke but at much higher levels.
The International Agency for Research on Cancer (IARC) considers acrylamide to be a “probable carcinogen.”
Mixed results in studies
The National Cancer Institute cites studies in rodents that show that exposure to acrylamide in drinking water increases the risk for several types of cancer.
People and rodents absorb and metabolize acrylamide at different rates, though, so it is difficult to use the results of animal studies to predict what will happen in people.
Lab tests in rodents also use acrylamide levels many times higher than what you would be exposed to by drinking coffee.
Results from studies in people looking for a link between exposure to acrylamide in the diet and cancer have been mixed.
A 2014 review of previous studies found no consistent link between dietary acrylamide and cancer. The authors caution that these studies may not have accurately estimated how much acrylamide people ingested in their food.
Dr. David Carbone, lung medical oncologist at The Ohio State University Comprehensive Cancer Center, said that people should be cautious about the chemical but within reason.
“While acrylamide is definitely something we should minimize in our diet, there is no demonstrated clinical adverse effect that has been demonstrated from the amount present in coffee,” he told Healthline, “in spite of multiple, nonindustry-sponsored studies attempting to find a link with cancer.”
In 2016, the IARC downgraded coffee from its “possible carcinogen” list.
Studies cited in the report found that drinking coffee did not increase the risk of cancers of the pancreas, female breast, or prostate. Coffee also reduced the risk of liver and uterine cancers.
Evidence on the cancer risk for more than 20 other cancers, though, is inconclusive.
Things more concerning than coffee
The lawsuit against coffee makers that led to this ruling was filed under California’s Safe Drinking Water and Toxic Enforcement Act, better known as Proposition 65.
Since 1986, this law has required warning labels for chemicals known to cause cancer or birth defects. More than 900 substances are currently on the list.
In response to a similar lawsuit, potato chip manufacturers reduced the acrylamide content of their products — and avoided having to carry warning labels.
The coffee industry has resisted changing how they roast the beans out of concern that it would impair the taste of the coffee. This led to the coffee warning labels.
Some experts, though, are concerned that overuse of Proposition 65 warnings may weaken consumer awareness of more severe hazards.
“I agree with finding roasting approaches for coffee that minimize acrylamide production,” said Carbone, “but labeling coffee as carcinogenic on this basis dilutes the impact of the label so as to lessen the effect of similar labeling on substances with demonstrated harm.”
California’s warning labels do put coffee’s risk into perspective.
Some substances are known to cause cancer in people. This includes cigarette smoking and radon gas. No level of these is safe.
With other compounds, your risk of cancer increases the more you are exposed.
Long-term heavy use of alcohol increases the risk of several cancers, such as cancer of the liver, mouth, throat, voice box, esophagus, colon, and rectum.
If you look at the top risk factors for cancers, coffee is low on that list.
The World Health Organization (WHO) reports that tobacco use is responsible for about 22 percent of cancer deaths worldwide.
One third of cancer deaths are also due to factors people can change — such as high body mass index, low intake of fruits and vegetables, lack of physical activity, and use of tobacco or alcohol.
And some substances that you put in your coffee, especially in large amounts, may be more harmful to your health than the coffee itself.
“The added ingredients in coffee — like sugar, cream, and syrupy sweeteners — do more harm than the minuscule amount of acrylamide you may be consuming in your coffee,” said Dr. David Friedman, a naturopathic doctor and clinical nutritionist, and author of “Food Sanity: How to Eat in a World of Fads and Fiction.”
Added sugars contribute to obesity and type 2 diabetes. Obesity is also linked to certain types of cancer, such as cancers of the pancreas, liver, and kidney.
“There are no warning labels on cream or sugar products, why should there be a warning label on our coffee?” said Friedman.
Some research shows that coffee may even provide health benefits, such as a reduced risk of cardiovascular disease and type 2 diabetes.
This is not to downplay the potential risks of acrylamide or other carcinogens. Or to suggest that you ignore warning labels.
The labels are there for good reason, but a label by itself might not be enough to help you decide what to do.
For that, you can turn to the NCI website, which provides information on most risk factors for cancer.
And if you are a heavy coffee drinker, the potential risks of acrylamide might give you another reason to reduce your coffee intake to “moderate.”
“While there are many studies showing the positive health effects of consuming coffee, overindulging can have negative health benefits,” Friedman told Healthline. “Enjoy one or three cups per day with no worries. But if you are a pot-of-coffee per day person, acrylamide may be a concern. So drink coffee in moderation.”