Today’s leading cola beverages contain high levels of a substance linked to cancer in animals, according to new research. 

An independent study commissioned by the Center for Science in the Public Interest (CSPI) uncovered  4-methylimidazole, or 4-MI, in Coke, Diet Coke, Pepsi and Diet Pepsi at levels 4.8 times greater than those allowed in beverages in California.

4-MI is a byproduct of the reaction that produces the caramel coloring in brown sodas. The chemical has been found to be carcinogenic in animal studies.   

The state of California has banned 4-MI in any amount that could potentially lead to one cancer case in 100,000 people. However the levels found in these 4 leading Cola brands indicated a lifetime risk of 5 cancers out of 100,000, assuming that people drink one soft drink per day. That risk rises to 10 cancers out of 100,000 people who drink only soft drinks containing caramel coloring. 

The federal Food and Drug Administration (FDA) sets an even more conservative risk limit for contaminant in food additives of 1 cancer in 1,000,000 people.  But the study reported rates of 4-MI that are associated with 48 cancers in 1,000,000. 

“Coke and Pepsi, with the acquiescence of the FDA, are needlessly exposing millions of Americans to a chemical that causes cancer,” said CSPI executive director Michael F. Jacobson.  “The coloring is completely cosmetic, adding nothing to the flavor of the product.  If companies can make brown food coloring that is carcinogen-free, the industry should use that.  And industry seems to be moving in that direction.  Otherwise, the FDA needs to protect consumers from this risk by banning the coloring.” 

In a letter to FDA Commissioner Margaret Hamburg Monday, CSPI shared the results of its study. The document served as an addition to the group’s petition of last year, which called on FDA to ban caramel colorings made with processes that generate 2-MI and 4-MI. 

The study also found 4-MI in Dr. Pepper and Diet Dr. Pepper, but at lower levels than the other 4 brands. A sample of Whole Foods’ 365 cola had a concentration of 47 micrograms of 4-MI in a can, as opposed to the almost 150 micrograms found in a can of Coca-Cola. 

The beverage industry responded to the study by pointing out that the European Food Safety Authority (EFSA), Health Canada and FDA have approved caramel coloring as safe for use in food and drink. 

“This is nothing more than CSPI scare tactics, and their claims are outrageous,” responded the American Beverage Association. “The science simply does not show that 4-MEI in foods or beverages is a threat to human health. In fact, findings of regulatory agencies worldwide, including the U.S. Food and Drug Administration, European Food Safety Authority and Health Canada, consider caramel coloring safe for use in foods and beverages. CSPI fraudulently claims to be operating in the interest of the public’s health when it is clear its only motivation is to scare the American people.”

Coca-Cola defended its product. 

“Unlike CSPI, The Coca-Cola Company deals in hard facts,” said company representative Ben Sheidler in an e-mailed statement to Food Safety News. “Fact:  The body of science about 4-MEI in foods or beverages does not support the erroneous allegations that CSPI would like the public to believe.  The 4-MEI levels in our products pose no health or safety risks.  Outside of California, no regulatory agency concerned with protecting the public’s health has stated that 4-MEI is a human carcinogen.  The caramel color in all of our ingredients has been, is and always will be safe. That is a fact.”  

FDA spokesman Doug Karas said the findings of the report were not of concern to consumer health. 

“A person would have to drink more than a thousand cans of soda in a day to match the doses administered in studies that showed links to cancer in rodents,” he told Bloomberg. 

The analysis was limited to 13 samples – 1 of Whole Foods’ 365 and 2 of each other brand – all purchased in the Washington, D.C. area. 

This article has been updated since its original publication. 

  • Studies have shown that 100% of the people who read the CSPI’s findings on this non-issue have wasted several minutes of their lives that they will never get back.

  • DMC

    Not me, Dave. After reading this report I’m done with colas.

  • Brenda Lou

    Whoa, this is vitally important information. Stop feeding soda to animals — it gives them cancer! And all this time I thought our dog died of old age. Silly me, it was the soda!
    CSPI respects neither science nor the public interest. CSPI is the food taliban.

  • Kristina

    Discredit the CSPI all you want, but it’s a well known fact that soda is unhealthy and we shouldnt be drinking it anyway. If this acticle gives people the push they need to stop drinking soda, and therfore make a step towards improving their health, then good for them.

  • Christine

    I have been doing research on this and sent a e-mail to CSPI asking about what levels of 4-MI was used in the testing on rats. They responded by giving me a link to a news report. I read the report and basically CSPI is basing their position on a California Law (Prop 65). No mention was made about how the study was conducted. I did alittle more research and discovered that California used extremely high amounts of 4-MI that would normally be used in industrial production. The amount in sodas is miniscule in comparison. But California, being California, decided to ban all use or require labeling that is could cause cancer. I am disappointed in CSPI that they are willing to be less than truthful in their “study.”

  • JulemryBoston

    California is often at the forefront of vital change in our country. I gave up Diet Coke years ago after learning about its ingredients. Recently a friend gave me some Diet Coke, and I was surprised at how awful it tasted to me, a former Diet Coke “addict.” Don’t deny science.

  • PJS

    The answer is simple, do not drink soda in California, anywhere else should be no risk as there is an obvious correlation between California and cancer