Speculation is mounting over aspartame potentially being labeled as a “possible carcinogenic to humans” following reports that the International Agency for Research on Cancer, an arm of WHO, has completed a safety review and is on the verge of publishing a report. 

Industry is closely monitoring the situation that has been developing this week following reports in international media.

The detail of the pending report is unclear at this stage, but the media reports have led to a number of statements from experts and trade organizations in the sweeteners space.

We have asked WHO for clarification following the initial report in Reuters yesterday, but have not yet received a response. 

What are organizations saying?
“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. IARC is not a food safety agency,” says the American Beverage Association.

“The FDA says JECFA (Joint FAO/WHO Expert Committee on Food Additives) is better suited to assess any risk associated with aspartame. And in its letter to WHO, HHS (US Department of Health and Human Services) said, an IARC review of aspartame… would be incomplete and its conclusions could be confusing to consumers.’ We [the American Beverage Association] share this concern.”

Kevin McConway, Emeritus Professor of Applied Statistics, Open University, stresses, “Even if Reuters’ sources are good and IARC are indeed going to say that aspartame is in their category of being ‘possibly carcinogenic to humans,’ I don’t think that will be the most important announcement about aspartame from a UN agency that day.” 

“An IARC categorization of possibly carcinogenic does not mean that a substance presents a risk to humans in normal circumstances, despite what the wording appears to say. The UN body that does have the job of assessing the risk from food additives, including aspartame, is JECFA. IARC has never considered aspartame before.” 

Mixed opinions
The International Sweetener Association (ISA) also released a statement saying that it joins food safety agencies across the globe in trusting the “scientific rigor” of the WHO’s joint FAO/WHO expert committee on food additives and is awaiting the full publication of the report next month.

However, the association also says that: “The ISA has serious concerns with preliminary speculation about the IARC opinion, which may mislead consumers about the safety of aspartame.” 

Furthermore, McConway explains that back in 1981, the JECFA established an acceptable daily intake of aspartame of 40 mg per kg of body weight per day. 

“To consume over that limit would require a huge daily consumption of Diet Coke or similar drinks. On 14 July, JECFA may change that risk assessment, or they may not. Reuters’ sources don’t appear to have given any information about that. So really, we do have to wait,” he adds.

Oliver Jones, a professor of chemistry at the Royal Melbourne Institute of Technology, Australia, shares the view of McConway. “We really need to wait and see the full IARC evaluation before we can make any firm conclusions.”

“Without that, we are shooting in the dark. We don’t know what the terms of the assessment were or what criteria they used to rule evidence in or out. What we can say is that IARC generally reviews the existing scientific literature on a particular substance or process, then weighs the evidence as to the likelihood said substance or process may be able to cause cancer under certain conditions or exposure.” 

Jones further explains that in this case, the IARC is going to list aspartame as a ‘possible carcinogen’ – the same as it previously classified eating red meat and using mobile phones – which means there is some evidence that it can cause cancer in humans but at present it is far from conclusive.  

“But we can’t be sure of anything until a formal announcement is made. It is also important to note that just because something may cause cancer does not mean it automatically does if exposed to it. The dose makes the poison,” says Jones.

What authority is appropriate?

Meanwhile, industry members and scientists are convinced that the prior research on aspartame being safe still stands and fears that the “misleading opinion” might drive consumers away from aspartame, which could lead to more sugar consumption.

John Sievenpiper, Professor in the Department of Medicine at the University of Toronto, says that aspartame has proven to be a safe tool to reduce calories and sugars in the diet and is one of the most extensively studied ingredients with over 40 years of high-quality science supporting its safety.

“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 based on low-quality studies,” says Kate Loatman, executive director at the International Council of Beverages Associations (ICBA).

She argues that even IARC agrees it is not the appropriate authority to undertake risk assessment based on actual consumption and does not make health recommendations.

“We remain confident in the safety of aspartame given the overwhelming weight of scientific evidence and positive safety determinations by food safety authorities in more than 90 countries around the world,” says Loatman.

“The best available evidence from large population studies shows that low and no-calorie sweeteners as a replacement strategy for added sugars are associated with reductions in important public health outcomes such as obesity, cardiovascular disease and death,” adds Sievenpiper.

Loatman concludes that a broader, more comprehensive food safety review underway by the WHO, the UN FAO and JECFA is welcomed.