For many of us, coffee is an essential part of our daily ritual. The smell, the taste, that boost of alertness—these are perks that many of us can’t (or don’t want to) live without. But what if, when waiting in line for a cup of coffee, you noticed a warning in big bold letters that its contents were known to cause cancer?
It’s a dilemma that Californians are facing thanks to a recent judicial decision in a Los Angeles Superior Court case that’s been pending since 2010. An organization called the Council for Education and Research on Toxics (CERT) brought suit against 91 coffee retailers and producers, including large chains like Starbucks and Whole Foods, to demand these companies comply with a California law called Proposition 65 and warn consumers of the presence of the chemical acrylamide in coffee.
The ultimate purpose of CERT’s legal effort “is to persuade…the coffee industry to get the acrylamide out of coffee,” Raphael Metzger, attorney for CERT, said in an email to SELF.
And this March, after multiple phases of the lengthy trial, the court ruled in CERT’s favor, meaning that the chains involved in the case should post warnings that clearly state that acrylamide is found in coffee or possibly face financial penalties up to $ 2,500 per person exposed daily, the AP reported. (The judge gave the defense additional time to file objections to the proposed ruling, so the final outcome is still to be determined.)
Proposition 65 requires California to keep an updated list of chemicals linked to cancer or reproductive harm. It also gives consumers the right to know if any chemicals on that list are in something they’re about to eat or drink, or will otherwise be exposed to them in some way.
Proposition 65 is unique to California, Marsha Cohen, professor at University of California Hastings College of the Law, whose specialty is food and drug law, tells SELF.
The list is updated each year and has grown to about 900 chemicals, according to the Office of Environmental Health Hazard Assessment (OEHHA), which oversees the Prop 65 program. Acrylamide is one of the chemicals on this list.
Acrylamide is a chemical that forms naturally in a wide variety of foods, including coffee and potatoes, when those foods are cooked or processed at high temperatures. Workers in certain industries—including construction, oil drilling, mining, plastics, and food processing—can be exposed to acrylamide through skin contact or inhalation. Cigarette smoke also contains acrylamide.
Under this legislation, no business can expose an individual to any chemical on the list “without first giving reasonable warning,” Andrew Torrez, a Maryland-based attorney who hosts the legal podcast Opening Arguments, tells SELF. Businesses have several options for giving their customers “reasonable warning,” but most California locales simply post a warning sign that is considered compliant, which you can order online.
According to Cohen, businesses who don’t comply with Prop 65 can be forced to do so through litigation, by either the Attorney General or an organization acting in the public’s interest (like CERT). Cohen says she wouldn’t be surprised to see some of the defendants in this case post the warnings immediately, though there are a few other options they can take if they wanted to continue fighting this. The judge could also decide that in addition to the required warnings, penalties should be imposed, and even calculated in a way that could cause them to pay financial penalties dating back to the start of the lawsuit.
Some have already abided by the judge’s current ruling: 7-Eleven settled out of the case in 2017, before the judge’s March ruling, agreeing to pay penalties and post the warning in its stores. And Starbucks has already posted the warnings even though the company has not settled out of the case at this point. (Remember, this ruling and Prop 65 only apply to these companies’ stores in California. So you probably won’t see this warning in your coffee shop in New York, for example.)
That being said, CERT v. Starbucks Corporation, et al is likely far from over. According to a statement issued in March by the National Coffee Association, whose members are some of the defendants in the suit, the coffee companies are considering all legal options available to them, including possible appeals.
But whether dietary acrylamide even deserves to come with a cancer warning, specifically for humans, is hotly contested.
Kathryn Wilson, doctor of science (Sc.D.), who researches cancer epidemiology at the Harvard T.H. Chan School of Public Health, tells SELF that agencies like the U.S. Food and Drug Administration (FDA) and the Environmental Protection Agency (EPA) each have systems for classifying whether things are carcinogenic, “and it’s often based on animal studies.”
That’s largely the case for acrylamide: In a 1984 study published in the peer-reviewed medical journal Cancer Letters, researchers fed mice various doses of acrylamide dissolved in water gradually over a two-week period and checked in over the course of a year to see whether tumor development occurred in the skin and lungs. They found tumors in both locations in some of the mice at one year, some of which were benign growths. In a larger, widely cited, two-year study from 1986 published in Toxicology and Applied Pharmacology, researchers fed laboratory rats acrylamide dosages of 2 mg, 0.5 mg, 0.01 mg, and 0.001 mg per day to assess its toxicity and whether the chemical would act as a tumor initiator compared to a control group consuming no acrylamide over the period. The results showed that cancerous tumor growths developed in rats that consumed 2.0 mg/kg/day, but there was no statistically significant increase of any tumors at the 0.1 or 0.01 mg/kg/day dose levels, and only one tumor type incidence significantly increased at the 0.5 mg/kg/day level.
In a 2010 toxicological review of the chemical from the EPA, the agency pointed to these particular animal studies as evidence for classifying acrylamide as “likely to be carcinogenic to humans.” The report reads, “In the absence of direct human data, the Friedman et al. (1995, 224307) and the Johnson et al. (1986, 061340) chronic rat drinking water studies were the only available cancer bioassays.”
But animal studies are not always reliable predictors of what will happen in humans in the same scenario. For one thing, rats and humans metabolize acrylamide differently. Also, some of the available mouse studies used mouse strains that are more susceptible to tumor growth than others.
So what do we know about the effects of dietary acrylamide in humans? A 2014 meta-analysis, published in the journal Nutrition and Cancer, that looked at the scientific literature on dietary acrylamide and cancer risk showed that the majority of the 40 studies included reported no statistically significant association between dietary acrylamide intake and various cancers, including breast, stomach, colorectal, prostate, lung, and other cancers. A few of the studies did link acrylamide to increased risks for renal, ovarian, and endometrial cancers, but the researchers deemed the assessment “inadequate.”
“[Human health] studies have mostly found no association between higher intake of dietary acrylamide and risk of cancer, [including] breast cancer, endometrial, ovarian, and prostate cancer,” Wilson says.
Critics of the coffee suit also argue that even though acrylamide is on California’s list of carcinogenic chemicals, the levels of acrylamide the average coffee drinker consumes daily have not been proven to be cause for concern.
“The first principle of toxicology is the dose makes the poison,” Carl Winter, Ph.D., a food toxicology scientist at the University of California at Davis, tells SELF. “It’s the amount of the chemical, not its presence or absence, which determines its potential for harm.”
Just how much acrylamide is in a cup of coffee varies but, on average, a single 160 ml cup of coffee delivers 0.45 μg, or micrograms, of acrylamide, according to a 2013 research paper from the Polish Institute of Public Health. That’s dramatically less than the amounts the lab rats were being fed (which would be like drinking thousands of cups of coffee per day).
When determining risk, scientists look at measures like frequency of exposure and how the chemical behaves in the human body. And “the levels [of acrylamide in coffee] are much, much, much lower than [have been seen to] induce cancer in animals,” Edward Giovannucci, M.D., professor of nutrition and epidemiology at Harvard T.H. Chan School of Public Health, tells SELF.
You obviously “shouldn’t drink water with acrylamide in it, like they’ve given to the rats—that would be bad for you,” Wilson adds.
Also, acrylamide isn’t known to bioaccumulate or build up in the human body over time. Winter points out the presence of dietary acrylamide was only discovered by Swedish researchers in 2002, in part because of just how quickly the human body metabolizes the chemical and eliminates it from the system via urine.
What’s more, swearing off coffee may not do anything to reduce the acrylamide in your diet, Wilson argues. “Cutting out a single food, like coffee, isn’t really going to have a huge impact,” she says. “Even if you get rid of it from coffee, people are still going to be taking in similar levels of acrylamide [from other sources].” Some amount of acrylamide can be found in almost everything we eat.
It's also not possible to eliminate the acrylamide content in coffee, at least not with existing beans and technology. The chemical forms naturally when the beans are being roasted. There’s just no way to do away with the natural production of acrylamide and still end up with something that tastes like coffee, Winter says. The chemical reactions that take place during the roasting process are important, Winter explains, who has studied food science for more than two decades. These chemical reactions, named the Maillard reaction after French chemist Louis-Camille Maillard, are the reactions between amino acids and reducing sugars that give browned and roasted foods like steak, bread, and coffee, their flavor, Wilson explains. “[They’re] responsible for most of the flavors and aromas of all kinds of [foods].”
Even if the coffee companies must abide by Prop 65 law, it’s hard to say whether these warnings about coffee (and other foods) and cancer will have much impact on consumers’ consumption.
In his email to SELF, Metzger wrote that his client’s goal is the removal of acrylamide from coffee (which, as we mentioned, doesn’t currently seem to be an option) in part because CERT also believes the warnings won’t be effective. “Coffee drinkers are compelled by their caffeine addiction to drink coffee…most consumers would continue drinking coffee despite receiving the legally required warnings,” Metzger explained.
California has made efforts to make the warning signs better and more worthwhile. At the request of OEHHA, researchers at University of California at Davis conducted surveys comparing existing Prop 65 warnings to proposed revised versions that included improvements like warning symbols and statements that specify the actual chemicals present (as opposed to using the more generic term “chemicals”). They found respondents said the new warnings were more informative, although new businesses are not actually required to use the new format, according to OEHHA’s website. But there’s no available data as of now to actually show whether people are changing their behaviors as a result of seeing warning information about chemical exposure thanks to Prop 65 signs.
Winter says the signs are so ubiquitous that most Californians don’t pay attention: “I was at Disneyland a couple weeks ago and all around Disneyland are the Prop 65 warnings. I’m not sure that they’re really doing much for people.”
Cohen even went so far as to hang one of the standard warnings in her home as a joke, but found “nobody noticed it.”
Ultimately, the evidence against acrylamide is pretty modest and limited to animal studies. So until there is more indisputable research to prove that acrylamide in coffee is indeed a serious cancer risk for humans, it’s really up to you to decide whether to continue drinking coffee or not.
Wilson says that, as a public health researcher, she fears these warnings could be a detriment. The law seems to encourage a very singular focus on individual chemicals, she explains; but what we eat, how much we eat, and how that impacts our health is in fact much more complex.
It makes much more sense to look at “dietary patterns [rather] than [the presence of] single chemicals,” she argues, adding that, “This whole decision in California just confuses people about coffee and its effects on health.”
On that note, coffee has also been associated with certain health benefits. A 2017 umbrella review published in the BMJ of 201 meta-analyses looked at health outcomes associated with coffee consumption and found a lower risk of mortality associated with three cups of coffee per day, and an association between high coffee consumption and lower risk of multiple types of cancer as well as some neurological, metabolic, and liver conditions. (The authors did not quantify high consumption, as studies and intakes vary from country to country, but it falls somewhere in the range of three to five cups per day.) Dr. Giovannucci adds that coffee consumption is also associated with, “lower risk of diabetes, cardiovascular disease, endometrial cancer in women, and some neurologic diseases like Parkinson’s.”
Dr. Giovannucci says putting warnings in a coffee shop encourages people to act fearfully rather than consider the evidence. “[It’s like saying] we shouldn’t go out for a walk because a bolt of lightning can come out of the blue and strike you…We can probably come up with a warning for almost everything single thing that we can do,” he points out.
Warning or not, whether you drink coffee, and just how much, is a personal choice, and it’s one that’s yours to make based on the evidence and whether the remaining uncertainties about coffee drinking and cancer outweigh the personal joy and benefit you might get as a coffee drinker.