Aspartame is one of the most popular artificial sweeteners. Next month, the WHO will declare it a possible carcinogen.

“[The International Agency for Research on Cancer (IARC)] has assessed the potential carcinogenic effect of aspartame,” the WHO said in a statement to Fortune. “Following this, the Joint FAO/WHO Expert Committee on Food Additives (JECFA) will update its risk assessment exercise on aspartame, including the reviewing of the acceptable daily intake and dietary exposure assessment for aspartame.”

The results of both evaluations will be released simultaneously on July 14.

Aspartame is used in common drinks and foods from Diet Coke to sugarless chewing gum to Dannon Activia yogurt. It’s also used in cough drops and some toothpaste. The WHO label indicates there is limited evidence linking aspartame to cancer. It is the lowest of three categories, with “probable carcinogen” (such as the herbicide glyphosate) and “carcinogenic to humans” (i.e., tobacco smoking and asbestos) the next possible steps.

The ruling from the IARC will reportedly not factor how much aspartame a person can safely consume. That advice will be determined by the JECFA.

The WHO last studied aspartame in 1981, determining an acceptable daily intake (40 mg per kilogram—2.2 lbs—of body weight). The new study was undertaken given the availability of new research results.

Industry backlash

Word of the pending declaration had put the food industry on the defensive. Coca-Cola did not immediately respond to Fortune’s request for comment, but the International Sweeteners Association—which counts PepsiCo and Skittles maker Mars Wrigley among its members—said it has “serious concerns with preliminary speculation about the IARC opinion.”

“IARC is not a food safety body,” said Frances Hunt-Wood, secretary general of the International Sweeteners Association in a statement. “No conclusions can be drawn until both reports are published. Aspartame is one of the most thoroughly researched ingredients in history, with over 90 food safety agencies across the globe declaring it is safe.”

The International Council of Beverages Associations, a trade organization for the nonalcoholic beverage industry, also condemned the leaking of the report, saying it “could needlessly mislead consumers into consuming more sugar rather than choosing safe no- and low-sugar options.”

The classification is the latest blow to sugar substitutes by the WHO. Last month, the group advised consumers to stop using non-sugar sweeteners for weight control, saying they did not help with weight loss. (That guidance, however, did not point to any possible health risks.)

Such rulings in the past have also had a massive impact on businesses which use the ingredients. In 2015, the IARC committee conducted a review that found glyphosate is “probably carcinogenic.”

By 2021 German drug and pesticide business Bayer had lost its third appeal against U.S. court verdicts that awarded damages of $86 million to customers blaming their cancer on use of its glyphosate-based weed killers.

Bayer insists the verdict cannot be reconciled with sound science or with product clearance from the federal environment regulator.

Bad news for the Diet Coke club

The list of celebrities and world leaders who are self-professed Diet Coke addicts reads more like the Hollywood Walk of Fame.

Actor Tom Hanks said his drink of choice is a “Cokeagne”—a can of Diet Coke mixed with Champagne—former President Donald Trump had a button added to the Oval Office which immediately requested the beverage, while former President Bill Clinton was also often pictured with a silver can in hand.

Meanwhile Ben Affleck, best known for films like Batman v Superman and Pearl Harbor, reportedly had a fountain serving Diet Coke added to his home, and in 2022 Elon Musk tweeted a photo of his bedside table which featured four open cans of the drink.