Coffee, Cancer, and California

Update June 6, 2019:Finally the drama is over: “The State of California has ruled to exempt coffee from Proposition 65 cancer warnings.” Boom. 💥

Update October 21, 2018: On October 12th, California’s Second Appellate District Court stayed the trial regarding coffee’s exemption from Prop 65. On October 15th, the OEHHA filed a request to disqualify Superior Court Judge Elihu Berle.

Update September 24, 2018: The OEHHA provided a copy of the public hearing held on August 16th. That video is embedded at the end of this article.

I have collected all of my Tweets on this subject into one Twitter moment. I will also keep that updated as I continue to follow any new developments.

Update June 29, 2018: The Office of Environmental Health Hazard Assessment (OEHHA) has proposed adding a new section to the California Code of Regulations stating that “chemicals in coffee that are produced as part of and inherent in the processes of roasting coffee beans and brewing coffee pose no significant risk of cancer.”


The proposed regulation will further the goals of the authorizing statute by clarifying that there is no significant cancer risk resulting from exposures to listed carcinogens in coffee that are created by and inherent in the processes of roasting coffee beans or brewing coffee. The regulation provides guidance to businesses concerning whether they need to provide Proposition 65 warnings for coffee. This regulation will therefore benefit the health and welfare of California residents by helping to avoid cancer warnings for chemicals in coffee that do not pose a significant cancer risk.

There is a period allotted for public comments before the public hearing, which is scheduled for August 16, 2018. More details are available from the OEHHA

A judge in L.A. recently ruled that packages of coffee must include a cancer warning label to comply with existing food-labeling law in the state of California. This has created a bit of a stir in the specialty coffee industry and also some concern/interest among coffee geeks (several of my coffee-geek friends sent me links about this). To get our collective head wrapped around this one, I think its good to break it down into the following areas; 1) the facts as we know them 2) the law as it’s written.

It is important to note that the coffee industry has a very clear stake in trying to control this message and therefore any information we get about acrylamide from the coffee industry should be taken with a grain of salt. For that reason, I have tried to gather sources that are industry-independent.

Acrylamide facts

  1. Acrylamide is produced when browning raw food materials, as part of the Maillard reaction, which is key to roasting coffee.

  2. Acrylamide is in brewed/extracted coffee.

  3. At consumption rates much higher than the average daily consumption by humans, acrylamide can cause tumors in lab rats.

  4. 100% of the US population consumes acrylamide as part of their diet. via

  5. The concentration of acrylamide in brewed coffee is about 17 parts-per-billion (ppb). For comparison, a toasted English muffin has 30ppb.

  6. Acrylamide is rapidly produced during the roasting process, but is also rapidly reduced by the same. Thus darker roasts contain less acrylamide than lighter roasts. (Achieving Sustainable Cultivation of Coffee: Breeding and Quality Traits, 2018, p. 317)

  7. Acrylamide is water soluable and is easily transferred from coffee powder to the beverage. Thus weaker brews (higher water-to-coffee ratio) contain less acrylamide than stronger brews (lower water-to-coffee ratio). (Achieving Sustainable Cultivation of Coffee: Breeding and Quality Traits, 2018, p. 317)

The science on dietary acrylamide is still relatively new; only first published in 2002, and is therefore still in flux. While doing research for this article, I came across these papers:

Lack of adverse health effects following 30-weeks of dietary exposure to acrylamide at low doses in male F344 rats (2016)

Effects of low dose acrylamide on the rat reproductive organs structure, fertility and gene integrity(2015)

Two-year carcinogenicity study of acrylamide in Wistar Han rats with in utero exposure (2014)

Proposition 65 facts

  1. Became a law in 1986

  2. Official name: Safe Drinking Water and Toxic Enforcement Act of 1986

  3. California’s Office of Environmental Health Hazard Assessment (OEHHA) is the official, lead agency

  4. The threshold that requires labelling is “one excess cancer for every 100,000 people exposed”

  5. The essence of the provision is that “persons be given clear and reasonable warning about risks from listed chemicals prior to being exposed to such chemicals.”

  6. The judge in this preliminary ruling stated the defendents “failed to satisfy their burden of proving by a preponderance of evidence that consumption of coffee confers a benefit to human health.”

  7. Defendents have until April 10 to file objections to the decision

My opinion

We don’t have enough scientific evidence yet to be able to quantify the risk of dietary intake of acrylamide (historically the concern has been acrylamide in cigarette smoke). However, the defendents have failed to prove to the judge that 1. acrylamide in coffee does not pose a significant risk and 2. that there was an acceptable, “alternative” risk level for acrylamide.

The law is the law and if it is determined by a judge that coffee must carry a label in California, then we must follow the law and label coffee appropriately. If I were a proprietor in California, I would figure out how to educate my customers about the law and the risk as we currently understand them. I’m still a bit conflicted though, because the libertarian in me says this is government overreach when we know so little about the risk.

However, let’s suppose I know I’m genetically predisposed to cancer or I’m currently in remission from cancer. I would want to know that there is a suspected carcinogen in coffee, even if it’s a small amount and for this reason; we know acrylamide is in a lot of foods, even if at low levels in individual foods. The concern is based on the total amount of acrylamide consumed over the course of a day—it is cumulative. So if I have a toasted bagel and a cup of coffee for breakfast, I’ve potentially doubled my acrylamide intake compared to a breakfast of fruit and tea. Currently there is no official, recommended rate of consumption from the FDA…

As a coffee guy, I hate to admit that coffee may contain a carcinogen. But that’s an emotional and selfish thought. If the science indicates there is a potential risk and the law states the risk must be indicated via labelling, then we have to follow the law or change it. Only time will tell how this one turns out.

A full and unedited copy of the public hearings held on August 16th, 2018:

Updated June 27, 2018: Added points six and seven to section “Acrylamide Facts.”
Updated June 29, 2018: Added update re: potential exclusion of coffee from Proposition 65
Updated August 21, 2018: Added link to Twitter moment.
Updated September 24, 2018: Embedded video of public hearings from 8/16/18

  1. Achieving sustainable cultivation of coffee: Breeding and quality traits. (2018). Burleigh Dodds Science Publishing.

Michael C. Wright

Michael is a licensed Q Grader, licensed Q Processor Pro, an Authorized SCA Trainer (AST), and most recently, a graduate with a degree in horticulture and a concentration in horticultural business management. He has over ten years experience in the coffee industry operating on both the supply and demand sides of the value chain.