“In short, the evidence that aspartame causes primary liver cancer or any other cancer in humans is very weak… Group 2b is a very conservative classification in that almost any evidence of carcinogenicity, however flawed, will put a chemical in that category or above.”

Paul Pharoah
Professor of Cancer Epidemiology, Cedars-Sinai Medical Center

“If the ADI is maintained by JECFA and other agencies and food safety authorities worldwide due to lack of scientific evidence, alarmism should not be generated. I don’t imagine that an institution like the WHO says that a drug poses a risk and the medicines agencies or authorities say otherwise, who are the ones that really evaluate the safety and efficacy of medicines.’’

Rafael Urrialde de Andrés
Professor, Biological Sciences at Complutense University of Madrid and Nutrition at San Pablo University,
Board Member of the Spanish Nutrition Society

“Classification alone is, at most, useless and in several cases—like in this case—is dangerous. It’s the dose that matters. Almost anything can be toxic if you have enough of it—even water.‘’

Angelo Moretto
Professor at the department of cardiothoracic and cardiovascular sciences and public health at the University of Padua, Italy

“These IARC reports are getting a bit farcical. In spite of the IARC’s conclusion that aspartame was ‘possibly carcinogenic to humans’, which got lots of media attention, another expert committee (JECFA), which actually investigates the magnitude of any risk, found ‘no convincing evidence from experimental animal or human data that aspartame has adverse effects’. “As they have said for 40 years, average people are safe to drink up to 14 cans of diet drink a day, which is about an old gallon — about half a large bucketful. And even this ‘acceptable daily intake’ has a large built-in safety factor.”

 Sir David Spiegelhalter
Emeritus Professor of Statistics, the University of Cambridge

‘’The [WHO committee’s] decision puts aspartame in the same category as things like aloe vera and bracken ferns. There is no convincing evidence that it causes cancer in humans and people shouldn’t be worried about getting cancer from aspartame in food and drink. Your overall diet is more important than individual foods or ingredients for reducing cancer risk. So, aim to eat a healthy, balanced diet, with more fruit, veg and wholegrains, and cut back on red and processed meats and foods high in fat, sugar and salt.”

Dr. Claire Knight
Senior Health Information Manager, Cancer Research UK

“Importantly, the same evidence that IARC considered and their report have been examined by JECFA, the WHO/FAO committee responsible for estimating whether there are any risks or likelihood of cancer developing associated with aspartame consumption. The committee saw no new reasons to change its longstanding recommendation of an acceptable daily intake 0-40 mg per kg of bodyweight without appreciable health risk.”

Prof Andy Smith
MRC Toxicology Unit, University of Cambridge

“Aspartame has not previously been classified by IARC, so its classification cannot yet have changed. It is in group 2B, not group 3, but the issue of the lack of good enough evidence does seem to apply to aspartame too.”

“But for now IARC have put aspartame in group 2, so they are saying it could possibly cause cancer under some circumstances, but that this is far from certain. So it remains perfectly possible that it cannot cause human cancers at all.”

“JECFA say that high estimates of actual consumption were 20 mg/kg bodyweight for children and 12 mg/kg of bodyweight for adults, which are well below the 40mg/kg ADI.”

Prof Kevin McConway
Emeritus Professor of Applied Statistics, Open University

“The Joint FAO/WHO Expert Committee on Food Additives committee has not changed its safety rating on Aspartame which they set at 40mg/kg body weight which for a 70 kg adult would mean drinking roughly 14 cans of Diet Coke a day, over a long period. This is consistent will all the major food safety agencies around the world who regularly conduct their own assessments and all classify aspartame as safe at the levels it is used at.”

“We are all exposed to carcinogens every day. Even things that the IARC classifies as class one carcinogens, such as UV light and alcohol, do not cause cancer just because you are exposed to them once. For example, if you get too much sun on the beach in summer you might get sunburn but you’ll recover. If you continually sunbathe with no sun protection then your risk of skin cancer goes up.”

Prof Oliver Jones
Professor of Chemistry, RMIT University

“It is somewhat difficult to judge this report as, at this stage all that IARC is publishing only a summary with a brief description of the interpretation of the available evidence by the expert working group, but, the full report with details of all the evidence considered will be published later. In short there is weak epidemiological evidence that aspartame is associated with an increased risk of primary liver cancer (that is cancer that arises in the liver rather than a cancer that started elsewhere and spread to the liver, or secondary liver cancer). This evidence comes from three studies that have reported an association but there is not much evidence to suggest that the association is ‘causal’ (association/correlation does not necessarily mean causation). In addition there was limited evidence that aspartame is carcinogenic in experimental animals, but this evidence was thought to have serious flaws. Finally, aspartame has some chemical properties that might be cancer associated.”

“In short the evidence that aspartame causes primary liver cancer, or any other cancer in humans is very weak. This is why it is classified as Group2B. Other examples of classified as Group2B are extract of aloe vera, diesel oil, caffeic acid found in tea and coffee. Group 2B is a very conservative classification in that almost any evidence of carcinogenicity, however flawed will put a chemical in that category or above.”

“This is reflected in the view of the Joint FAO/WHO Expert Committee on Food Additives who concluded that there was no convincing evidence from experimental animal or human data that aspartame has adverse effects after ingestion. They noted that aspartame is rapidly metabolised into chemicals found in many common foods. Thus the JECFA had no reason to alter their current recommendation on an acceptable daily intake of aspartame.”

“The general public should not be worried about the risk of cancer associated with a chemical classed as Group 2B by IARC.”

Prof Paul Pharoah
Professor of Cancer Epidemiology, Cedars-Sinai Medical Center, Los Angeles

“The conclusions of IARC and JECFA on aspartame reflect the respective approaches taken by the two committees. IARC has classified aspartame as 2b, which reflects a lack of confidence that the data from experimental animals or from humans is sufficiently convincing to reach a clear conclusion that aspartame is carcinogenic. But IARC did conclude that any carcinogenicity was most likely through an indirect effect and not through direct interaction with DNA (genotoxicity). JECFA reviewed all of the toxicological effects of aspartame including carcinogenicity and genotoxicity. The weight of evidence did not support any carcinogenic effect and JECFA found no basis to change its previously established acceptable daily intake. Hence, exposure at current levels would not be anticipated to have any detrimental effects.”

Prof Alan Boobis
Emeritus Professor of Toxicology, Imperial College London

“The new data in the IARC report suggests a possible link between liver cancer and aspartame in some observational studies. There has been a marked increase in liver cancer related to obesity in several Western countries, notably in the USA, that is associated with non-alcoholic fatty liver disease. Type 2 diabetes and obesity are major cause of fatty liver disease. Sugar intake has been previously linked to fatty liver disease as it encourages the synthesis of fat in the liver. There is no evidence that aspartame increases fat accumulation in the liver. People with diabetes or who are obese are more likely to use artificial sweeteners compared with those who are not obese. Consequently, this association while consistent may not be causal.”

“IARC noted the evidence is limited because they cannot rule out confounding factors and because the data from animal studies is inconsistent, aspartame was classified 2b – a possible cancer hazard. JECFA, however, does not believe the risks posed by aspartame are anything to be concerned about providing the amounts of aspartame consumed are below the acceptable daily intake, which are unlikely to be exceeded in practice.”

Prof Tom Sanders
Professor emeritus of Nutrition and Dietetics, King’s College London

“The publication of the IARC and JECFA opinion is very welcome as it ends the speculation about the safety of Aspartame. The two WHO agencies have done what they are supposed to do: IARC has reviewed the data and found some very limited evidence that Aspartame could cause cancer – and based on the same data JECFA has concluded that a consumption up to 40 mg per kg of body weight per day is safe and there is no need to change current recommendations.”

“It is unfortunate that leaking some information might have created unnecessary uncertainty and concern as consumers might be rightfully worried if they are told that something that is in many foods could cause cancer. The published opinion puts this into perspective and makes it very clear that there is no cause for concern when consumed at the current amounts. Scientific advisory bodies are often unable to react quickly and respond to an emerging story so it’s good they will now have both the IARC and JECFA assessments to digest and respond to.”

“This illustrates also the importance of distinguishing between hazard and risk and highlights the difficulty in communicating hazards: sunlight is a hazard as it can cause cancer, but the risk depends on the amount of sun light and whether we use protection. Likewise, even if Aspartame causes cancer at very high amounts, there is no risk when consuming it at the amounts that are permitted in foods.”

Prof Gunter Kuhnle
Professor of Nutrition and Food Science, University of Reading