Aspartame sweetener a possible carcinogen, says WHO's Cancer Research Agency

Geneva [Switzerland], June 29 : Aspartame, one of the world's most common artificial sweeteners, is set to be declared a possible carcinogen next month by a leading global health body, pitting it against the food industry and regulators, reported Reuters.

Aspartame is used in products from Coca-Cola diet sodas to Mars' Extra chewing gum and some snapple drinks. The International Agency for Research on Cancer (IARC) and the World Health Organization's (WHO) cancer research arm will list it as "possibly carcinogenic to humans" for the first time in July, according to two sources with knowledge of the process.

Following a meeting of the group's external experts earlier this month, the IARC ruling is intended to assess whether something is a potential hazard or not, based on all the published evidence.

It does not take into account how much of a product a person can safely consume. This advice for individuals comes from a separate WHO expert committee on food additives, known as the Joint WHO and Food and Agriculture Organization's Expert Committee on Food Additives (JECFA), alongside determinations from national regulators, Reuters reported.

In the past, similar IARC rulings for different substances have raised concerns among consumers about their use, led to lawsuits, and pressured manufacturers to recreate recipes and swap for alternatives. This has led to criticism that the IARC's assessments can be confusing to the public.

JECFA and the WHO committee on additives are also reviewing aspartame use this year. Its meeting began at the end of June and is due to announce its findings on the same day that the IARC makes public its decision on July 14, as per Reuters.

Since 1981, JECFA has said aspartame is safe to consume within accepted daily limits. For example, an adult weighing 60 kg (132 pounds) would have to drink between 12 and 36 cans of diet soda - depending on the amount of aspartame in the beverage - every day to be at risk. Its view has been widely shared by national regulators, including in the United States and Europe.

An IARC spokesperson said both the IARC and JECFA committees' findings were confidential until July. But they added that they were "complementary", with IARC's conclusion representing "the first fundamental step to understand carcinogenicity". The additives committee "conducts risk assessment, which determines the probability of a specific type of harm (e.g., cancer) to occur under certain conditions and levels of exposure," Reuters reported.

Whereas, industry and regulators fear that holding both processes at around the same time could be confusing, according to letters from U.S. and Japanese regulators seen by Reuters.

Nozomi Tomita, an official from Japan's Ministry of Health, Labour and Welfare wrote in a letter on March 27 to WHO's deputy director general, Zsuzsanna Jakab, "We kindly ask both bodies to coordinate their efforts in reviewing aspartame to avoid any confusion or concerns among the public."

The letter also called for the conclusions of both bodies to be released on the same day, as is now happening. The Japanese mission in Geneva, where the WHO is based, did not respond to a request for comment, according to Reuters.

However, Frances Hunt-Wood, the secretary general of the International Sweeteners Association (ISA) said, "IARC is not a food safety body and their review of aspartame is not scientifically comprehensive and is based heavily on widely discredited research," The body, whose members include Mars Wrigley, a Coca-Cola unit and Cargill, said it had "serious concerns with the IARC review, which may mislead consumers".

Kate Loatman, the International Council of Beverages Associations' Executive Director said public health authorities should be "deeply concerned" by the "leaked opinion", and also warned it "could needlessly mislead consumers into consuming more sugar rather than choosing safe no-and low-sugar options," Reuters reported.

Aspartame has been extensively studied for years. Last year, an observational study in France among 100,000 adults showed that people who consumed larger amounts of artificial sweeteners including aspartame had a slightly higher cancer risk, according to Reuters.

Furthermore, it followed a study from the Ramazzini Institute in Italy in the early 2000s, stating that some cancers in mice and rats were linked to aspartame.

However, the first study could not prove that aspartame caused the increased cancer risk. The questions were raised about the methodology of the second study, including by EFSA, which assessed it, reported Reuters.

The IARC said it had assessed 1,300 studies in its June review. Aspartame is authorized for use globally by regulators who have reviewed all the available evidence. Also, major food and beverage makers have for decades defended their use of the ingredient.

The soft drinks giant Pepsico tweaked recent recipes which demonstrated the struggle the industry has when it comes to balancing taste preferences with health concerns. Pepsico removed aspartame from sodas in 2015, bringing it back a year later, but removed it again in 2020, according to Reuters.

Sources close to the IARC said that Aspartame has been listed as a possible carcinogen which is intended to motivate more research, which will help agencies, consumers and manufacturers draw firmer conclusions. But it will also likely ignite debate once again over the IARC's role, as well as the safety of sweeteners more generally.

Last month, the WHO published guidelines and advised consumers to not use non-sugar sweeteners for weight control. The guidelines caused an uproar in the food industry, which argues that they can be helpful for consumers wanting to reduce the amount of sugar in their diet, reported Reuters.