For people who avoid caffeine, decaffeinated coffee seems to be a harmless option. But some health advocacy groups who argue otherwise are calling on the US Food and Drug Administration to ban a key chemical involved in the decaffeination process because of cancer concerns.
Decaf coffee
This chemical is methylene chloride, a colorless liquid that is used in certain industrial processes, “including in paint stripping, pharmaceutical manufacturing, stripper manufacturing and metal cleaning and degreasing”according to the Occupational Safety and Health Administration, writes edition.cnn.com.
Methylene chloride has long been known to be carcinogenic, having been designated as such by the National Institutes of Health's National Toxicology Program, the Environmental Protection Agency and the World Health Organization, said Dr. Maria Doa, senior director of chemical policy for the Environmental Defense Fund, one of five groups and individuals behind two food additive and colorant petitions sent to the FDA in November.
The FDA filed the petitions on December 21 and accepted public comments on the notice of filing until March 11.
“In addition to being carcinogenic, methylene chloride can cause other harmful health effects such as liver toxicity and, at higher exposures, neurological effects and in some cases death,” Doa added via email. These risks are in the context of acute external exposure to high levels of the chemical or its ingestion as such, according to the US Centers for Disease Control and Prevention.
The toxicity of this chemical led the EPA to ban its sale as a paint stripper in 2019; in 2023, the agency proposed banning its sale for other consumer uses and for numerous industrial and commercial uses, Doa said. But food uses regulated by the FDA under the federal Food, Drug, and Cosmetic Act remain. (California's state assembly—which has one of the world's largest economies, often influencing the rest of the nation—recently introduced a bill seeking to ban the use of methylene chloride in the decaffeination process.)
The Environmental Defense Fund and its co-petitioners argue that by allowing methylene chloride in food, the FDA “didn't take into account” of a 66-year-old addition to federal law called the Delaney Clause, which requires the FDA to ban food additives that have been shown to cause or induce cancer when ingested by humans or animals.
“Thus, these chemicals categorically cannot and should not be considered safe,” said Doa.
The FDA said it is currently reviewing the petitions, but does not comment on them while they are under review, an FDA spokesman said in a statement.
Here's what experts and the FDA have to say about the clause in the modern context and what you should know about the safety of decaffeinated coffee.
What we know about methylene chloride
The FDA has only one regulation that allows the use of methylene chloride as a solvent for decaffeinating coffee, stating that “methylene chloride residues must not exceed 10 parts per million (0.001%) in decaffeinated roasted coffee and decaffeinated soluble coffee extract (instant coffee)”.
“While methylene chloride may be indirectly involved in food processing, such as in the decaffeination of coffee beans, residue limits have been established to limit exposure,” an FDA spokesman said via email. “Any food product containing residues of methylene chloride above the established limits is not allowed for sale or consumption”.
National Coffee Association President and CEO William Murray said banning European-style decaffeinated coffee — the kind that uses methylene chloride — “would defy science and harm the health of Americans.”
“There is no evidence that decaffeinated by the European Method poses any risk.” he added via email. “Indeed, the overwhelming weight of independent scientific evidence shows that consumption of European Method decaffeinated coffee, like all coffees, is associated with reduced risk of several types of cancer and other significant health benefits.”
But the FDA's latest decision on the use of this chemical for coffee “is decades old and clearly out of date,” Doa said.
“There is more information about the toxicity of methylene chloride and the levels at which it causes toxicity,” she added. “This information, as well as more recent information on the amount of coffee we drink – just think of the different sizes now available at coffee shops – is essential to developing a current picture of the risk that residual methylene chloride might pose .”
These days, many people consume larger portions of beverages or foods than the smaller standard sizes of a few decades ago, said Monique Richard, a registered dietitian nutritionist and owner of Nutrition-In-Sight, a private practice in Tennessee. While a standard cup of coffee was 5 or 8 ounces at one time, she noted that the smallest size at the local coffee shop today is probably 12 ounces.
“But there still isn't a lot of clear or conclusive research to show that ingesting residual levels in coffee specifically will cause cancer or other problems” said Richard, who was not involved in the petitions.
However, “we certainly want to obviously be proactive and be aware of some of these things,” Richard added. “We're exposed to so much now that anything we can control or question and lessen that potentially harmful exposure will be beneficial.”
Research into what the human body can handle in terms of toxic load is constantly evolving. Researchers have learned more about genetic makeup and gene expression, which can provide information about what cells can tolerate in terms of an attack on the body. “So it might be less about what's actually in the coffee, but what other factors are affecting your body?” Richard said. “Even a 'tiny' amount could be significantly destructive at the cellular level over time,” she added.
Methylene chloride has long been commonly used in the decaffeinated coffee industry, but some companies have added alternative methods to their toolkit or discontinued use altogether.
Starbucks, for example, has three methods of decaffeination: the natural decaffeination process, which uses liquid carbon dioxide forced into stainless steel tanks at high pressure, extracting and dissolving the caffeine. Then there's the Swiss Water Process, which decaffeinates the coffee beans by soaking them in warm water. The warm water takes on the flavor of the beans, then is passed through an activated carbon filter that captures the caffeine molecules. Then the beans are soaked in that water to reintroduce the flavor.
Starbucks says its direct contact method is the most commonly used process, which involves a solvent that, along with other liquids used, is eventually evaporated from beans that are steamed, washed and roasted at over 400 degrees Fahrenheit (204 degrees Celsius).
CNN reached out to Starbucks to confirm what that solvent is, as well as Dunkin' to determine what the decaffeination process entails.
The Clean Label Project, an organization that tests consumer products for hidden industrial and environmental contaminants, detected methylene chloride in seven of the 17 coffee brands tested, according to the petition.
The levels of methylene chloride found were very low in most of the seven samples, the NCA said – while the FDA's safe limit is 10 parts per million, one brand had 1.4 parts per million, another contained 3. 5 parts per million, and another 8.9 parts per million.
Doa stated that the petitioners are of the opinion that “although levels of methylene chloride may generally be minimal, it is completely unnecessary as safer processes are available and used to decaffeinate coffee”said Doa.
She added that in addition to exposing consumers to low levels, workers exposed to methylene chloride in factories are at higher and unnecessary risks.
What you can do
Whether or not the FDA will ultimately ban methylene chloride is a decision that could take years.
But if you want to avoid potential methylene chloride exposure, when buying decaffeinated coffee, look for product packaging with labels like “solvent free”“Swiss Water processed” or “certified organic“, states the DOA.
“As a consumer, always do your research”, Richard said. “Research everything you can about the company. Ask these questions if you can access a customer hotline on their website.”
Also, consider how often you drink decaffeinated coffee, how much, and why, she added.
“If you're concerned about this and just confused, there are plenty of caffeine-free substitutes,” Richard said. These include drinks made from chicory root, figs and barley, dandelion root, mushroom elixirs, cocoa, rooibos and yerba maté.
