Today the International Agency for Research on Cancer (IARC) of the World Health Organization classified the artificial sweetener aspartame as possibly carcinogenic to humans. Aspartame is used in Diet sodas such as Diet Coke and Diet Pepsi as well as Kool Aid, Crystal Light and other artificially sweetened drinks, candies, sugar-free chewing gum, children’s medicines and vitamins.

As the US Right To Know documents, decades of science links aspartame to many other health problems including cardiovascular disease, stroke, seizures, mood disorders and headaches. The chemical is also tied to weight gain, increased appetite and obesity.

Dr. Devra Davis, President of Environmental Health Trust, has worked on aspartame for years, recommending safer alternatives to Diet Soda and other artificially sweetened products. She has long called for caution with aspartame due to the evidence of cancer in animals. She published a letter with colleagues in 2008 that concluded, “recent reports of Soffritti finding that aspartame significantly increases the risks of tumors in rodents, with a doubled risk in those in which exposures begin prenatally, the Food and Drug Administration should review its approval of aspartame.”

Watch the WHO press conference

In May, the World Health Organization advised people to avoid non-sugar sweeteners, including aspartame, for weight control. The WHO’s Joint Expert Committee on Food Additives (JECFA) today said aspartame is safe to drink at current “acceptable” levels which amount to multiple cans of soda per day.

• Carcinogenicity of aspartame, methyleugenol, and isoeugenol – Lancet Oncology

• Aspartame is a possible cause of cancer in humans, a WHO agency says, New York Times

Theodora Scarato, Executive Director of Environmental Health Trust comments that “It takes decades for science to catch up policy.  In 2011, the radiation emitted by cell phones and wireless networks was classified as a “possible” human carcinogen by the World Health Organization IARC as well.   The scientific evidence has substantially increased over the last decade with NIH/National Toxicology Program studies showing “clear evidence of cancer” and DNA damage. Numerous WHO/IARC experts now state that the new animal evidence suggests that the next time the International Agency for Research on Cancer reviews the research, cell phone radiofrequency radiation will be upgraded to a “probable” or even a  “proven” human carcinogen.”  

An IARC Monographs working group (WG) of 25 independent experts from 12 different countries – all assessed as free from conflicts of interest – was convened in Lyon on 6–13 June 2023 to evaluate aspartame. The IARC working group classified aspartame as possibly carcinogenic to humans (Group 2B). Excerpts of their summary cites evidence including:

“Limited evidence for cancer in humans, based on findings for liver cancer (specifically, hepatocellular carcinoma). Among the available cancer studies in humans, there were only three studies on the consumption of artificially sweetened beverages that allowed an assessment of the association between aspartame and liver cancer. The three studies (which included four large cohorts) were conducted within the European Prospective Investigation of Cancer and Nutrition (EPIC) cohort, 2 a pooled analysis of the National Institutes of Health (NIH)-American Association of Retired Persons (AARP) cohort and the Prostate, Lung, Colorectal and Ovarian Cancer Screening (PLCO) cohort, 3 and the Cancer Prevention Study (CPS)-II cohort. 4 In these studies, consumption of artificially sweetened beverages was considered a proxy for aspartame exposure, as supported by evidence on the country and time period of aspartame use in beverages. In all three studies, a positive association was observed between consumption of artificially sweetened beverages and risk of liver cancer, either overall or in important subgroups of the studied populations, but bias or confounding could not be ruled out as an explanation for the positive findings.”

“There was also limited evidence for cancer in experimental animals. There was an increased incidence of malignant neoplasms or a combination of benign and malignant neoplasms in two species (mouse and rat) of animals of both sexes seen in three published studies.”

The WHO IARC recommends  additional research  and states:

“What is WHO recommending on the consumption of sugars and non-sugar sweeteners? In both adults and children, WHO recommends reducing the intake of free sugars to less than 10% of total energy intake (strong recommendation). WHO suggests a further reduction of the intake of free sugars to below 5% of total energy intake (conditional recommendation). Page10 WHO suggests that non-sugar sweeteners not be used as a means of achieving weight control or reducing the risk of noncommunicable diseases (conditional recommendation). WHO reaffirms its recommendation to not use non-sugar sweeteners as a means of achieving weight control or reducing the risk of noncommunicable diseases as the evidence still suggests that their use does not help with long-term weight control and may increase risk of type 2 diabetes, cardiovascular diseases and premature mortality.”