WHO’s cancer research agency, the International Agency for Research on Cancer (IARC), has been reviewing the carcinogen effect that aspartame, a common sweetener, has on the human body. While the official results will be released on 14 July, sources have told Reuters that the substance will be classified as a potential threat.
Aspartame is a non-nutritive sweetener widely used since the 1980s as a table-top sweetener, in low calorie beverages, such as diet soda, in prepared food and in chewing gum, gelatine, ice cream and breakfast cereals, as well as in medications, such as cough drops, and other products, such as toothpaste.
According to Interesting Engineering, aspartame is 200 times sweeter than sucrose, main constituent of white sugar. Common products that use the sweetener are Diet Coca-Cola, Fanta Zero and Mars’ Extra chewing gum.
The IARC only establishes whether a substance poses a possible threat to humans, while WHO’s Expert Committee on Food Additives (JECFA) determines a safe daily intake. Updated recommendations from JECFA will also be published on 14 July, in the meantime, sources told Reuters that IARC’s classification for aspartame is “possible carcinogenic to humans”, the lowest of the risk levels.
The safety of aspartame was evaluated in 1981 by a joint committee formed by UN’s Food and Agriculture Organisation (FAO) and JECFA, a programme of risk assessment for additives and contaminants in food. At the time, an acceptable daily intake (ADI) was established at 40 mg/kg body weight per day. This means that a 60 kg adult would have to drink between 12 and 36 cans of diet soda daily to be at risk, depending on how much aspartame is in the drink.
However, given the new research studies conducted since 1981, the WHO Advisory Group recommended last year that the IARC evaluates aspartame with high priority during 2020–2024 (for cancer hazard identification). Aspartame was also recommended for evaluation by the WHO/JECFA committee (for risk assessment).
An IARC Monographs Working Group of independent international experts carries out the evaluation. The independent experts assemble and critically review the scientific evidence according to strict criteria, which focus on determining the strength of the available evidence that the agent causes cancer. More than 7000 references were collected and screened for the assessment and approximately 1300 studies were included in the review and made available to the Working Group.
IARC classification criticism
The IARC’s classification procedure has been contested in the past for being misleading to consumers. It only establishes the potential of a substance to cause cancer, without providing any additional information on intake levels.
In 2015, the group classified glyphosate as “probably carcinogenic”, causing a worldwide stir over the use of herbicides. Despite, other agencies, including the European Food Safety Authority (EFSA) contesting this classification, it still had a great impact on producers. Bayer lost a lawsuit from customers blaming the company’s use of glyphosate in herbicides for their cancer.
“IARC is not a food safety body and their review of aspartame is not scientifically comprehensive and is based heavily on widely discredited research”, said Frances Hunt-Wood, secretary general of the International Sweeteners Association (ISA), which includes members like Coca-Cola and Mars Wrigley.
Even IARC agrees it is not the appropriate authority to undertake risk assessment based on actual consumption and that it does not make health recommendations.
Kate Loatman, Executive Director, International Council of Beverages Associations
Reacting to the news, the International Council of Beverages Associations (ICBA) pointed to WHO research that concluded in April 2022 that there is “no significant association” between higher consumption of low- and no-calorie sweeteners (measured through beverage consumption) and cancer mortality, nor any type of cancer.
“While it appears IARC is now prepared to concede that aspartame presents no more of a hazard to consumers than using aloe vera, public health authorities should be deeply concerned that this leaked opinion contradicts decades of high-quality scientific evidence and could needlessly mislead consumers into consuming more sugar rather than choosing safe no- and low- sugar options – all on the basis of low-quality studies”, warned Kate Loatman, ICBA Executive Director.
The “possible carcinogenic to humans” classification means that there is either limited scientific evidence aspartame can cause cancer in humans, less than sufficient evidence it causes cancer in animals or some evidence about the substance’s characteristics. The same category also includes radiofrequency electromagnetic fields associated with using mobile phones, while other debated classifications are eating meat and working overnight in the “probably carcinogenic” group.
