Does Coffee Cause Cancer? California Officials Reject Law to Warn Consumers of Cancer-Causing Chemical

Coffee beans in a cup at a cocoa and vanilla production facility. HELENE VALENZUELA/AFP/Getty Images

Luckily for coffee sellers in California, state officials rejected a ruling that coffee shops must warn drinkers about a cancer-causing chemical in their brews.

California's Proposition 65 requires sellers to inform customers about chemicals known to cause cancer, birth defects or reproductive problems. Coffee contains acrylamide, which has been shown to cause cancer in mice when given concentrated doses, so, in March, a court ordered that coffee companies must add a cancer warning label.

However, coffee companies fought that decision, and recently California officials decided to reject the rule. Now, California coffee can remain warning-free.

The science regarding the health effects of coffee is controversial and inconsistent. While acrylamide, which is created naturally through the brewing process, has demonstrated cancer-causing properties in mice, researchers have not performed these tests on humans, and the small amount in your morning brew may or may not ever hurt you.

Furthermore, the studies have gone back and forth countless times regarding the verdict on coffee's effect on human health. A study published in 2009 suggested that drinking five or more cups of coffee a day could increase one's risk of ovarian cancer, for instance. Another published in 2008 suggested that three cups a day could reduce ovarian cancer risk.

It's difficult for scientists to be sure what the overall health effect of coffee is, especially when companies that sell coffee fund studies on coffee that have positive outcomes. Still, California officials decided that warning consumers of carcinogens in coffee was taking Proposition 65 too far, and that people would just start ignoring these warnings if they see them too often. "The proposed regulation is based on extensive scientific evidence that drinking coffee has not been shown to increase the risk of cancer and may reduce the risk of some types of cancer," officials wrote, according to AP.

An attorney for The Council for Education and Research on Toxics, which won the original court case against coffee companies, asking them to include the Proposition 65 warning, was dismayed at the decision to reject the ruling.

"The takeaway is that the state is proposing a rule contrary to its own scientific conclusion. That's unprecedented and bad," Raphael Metzger, the attorney, told CBS. "The whole thing stinks to high hell."