WHO Agency Reportedly to List Aspartame as 'Possibly Carcinogenic to Humans'

A World Health Organization' agency will list the widely used artificial sweetener aspartame as "possibly carcinogenic to humans" July 14, Reuters reported, citing two sources familiar with the situation.

International Agency for Research on Cancer (IARC) listings do not say anything about how much of a substance a person must consume to be at risk, but they can be hugely influential. The body's 2015 determination that glyphosate was "probably carcinogenic to humans" has helped plaintiffs to win lawsuits and appeals against Bayer claiming that use of its glyphosate-containing herbicides caused their cancer.

"We have to wait until July 14 and see how it determines the assessment and in which group it encompasses it," Rafael Urrialde de Andrés, who sits on the board of directors of the Spanish Society of Nutrition and is a professor at the Faculty of Biological Sciences of the Complutense University of Madrid and the Faculty of Pharmacy of the San Pablo-CEU University, said in a statement. "From then on, the food safety agencies and authorities will have to determine whether to reevaluate, ban it, or maintain authorization and under what conditions."

"CSPI has long recommended that consumers avoid aspartame because of studies showing the sweetener caused cancer in animals."

Aspartame is a popular artificial sweetener used in products from Diet Coke to Mars chewing gum. Around 95% of carbonated drinks and 90% of teas that use artificial sweeteners use aspartame, according to The Washington Post.

It has been deemed safe in more than 90 countries including the U.S., and the Food and Drug Administration (FDA) has affirmed its safety five different times. However, there have been calls from scientists to reevaluate the chemical based on a series of Italian studies finding it caused tumors in rats, and the Center for Science in the Public Interest (CSPI) has aspartame on its list of chemicals to avoid.

"CSPI has long recommended that consumers avoid aspartame because of studies showing the sweetener caused cancer in animals," the group tweeted in response to the Reuters story.

The IARC lists exposures as either possibly carcinogenic, probably carcinogenic, or carcinogenic to humans, with the ranking dependent on the strength and extent of the evidence. Experts point out that the IARC is assessing whether foods or chemicals represent potential hazards.

"This means that the IARC experts do not assess whether, in practice, a substance or exposure presents a cancer risk to people," Kevin McConway, emeritus professor of applied statistics at Open University, explained. "Instead they assess whether it would ever be capable of presenting a risk, under any circumstances, even if the only harmful circumstances are really, really unlikely to occur."

Because of this, the body has been criticized for causing unnecessary worry with its listings, such as its warnings that eating red meat and working overnight were probably carcinogenic, and that mobile phones were possibly carcinogenic, The Guardian reported.

That said, another World Health Organization (WHO) body is also scheduled to present a ruling on aspartame July 14 that could provide greater clarity. The Joint WHO and Food and Agriculture Organization's Expert Committee on Food Additives (JECFA), which sets dosage recommendations, is reviewing aspartame from June 27 to July 6, according to The Washington Post. It had previously set the safe level at 40 milligrams per kilogram of body weight per day, McConway said.

"To consume over that limit would require a very large daily consumption of Diet Coke or similar drinks," McConway added. "On 14 July, JECFA may change that risk assessment, or they may not."

Industry groups are already pushing back against a potential change in aspartame's status.

"IARC is not a food safety body and their review of aspartame is not scientifically comprehensive and is based heavily on widely discredited research," Frances Hunt-Wood, the secretary general of the International Sweeteners Association said, as Reuters reported.

Kate Loatman, the executive director of the International Council of Beverages Associations, said that public health bodies should be "deeply concerned" by the "leaked opinion" that she said "could needlessly mislead consumers into consuming more sugar rather than choosing safe no-and low-sugar options."

Even before the Reuters leak, industry and national regulatory bodies were concerned with the news that IARC and JECFA were reviewing aspartame at all, The Washington Post reported.

"There is a broad consensus in the scientific and regulatory community that aspartame is safe. It's a conclusion reached time and time again by food safety agencies around the world," Kevin Keane, American Beverage Association interim chief executive, told the Post last week. "The fact that food safety agencies worldwide, including the FDA, continue to find aspartame safe makes us confident in the safety of our products. And people all over the world should be, too."

The FDA also sent a letter to WHO in August 2022 advising against having two subcommittees consider aspartame.

"In our opinion, a concurrent review of aspartame by both IARC and JECFA would be detrimental to the scientific process and should not occur," Mara Burr, director of the Office of Multilateral Relations in the Department of Health and Human Services' Office of Global Affairs, wrote in the letter.

Burr argued that the review should be conducted by JECFA alone.

"They seem to be worrying in advance of the most authoritative review of the safety of this product," CSPI director Peter Lurie told The Washington Post. "But even if FDA chose to ignore what WHO has to say, the IARC pronouncement would still have a lot of pull in the rest of the world."