International Agency for Research on Cancer (IARC)
IARC is the cancer research agency of the WHO. One of its major roles is to identify causes of cancer.
IARC classifies aspartame as “possibly carcinogenic to humans” (Group 2B), based on
limited evidence it might cause cancer (specifically liver cancer) in people. IARC also notes there is
limited evidence for cancer in lab animals and
limited evidence related to possible mechanisms for it causing cancer.
It’s important to know that IARC classifications are based on the
strength of the evidence of whether something can cause cancer in humans,
not how likely it is to cause cancer. The Group 2B classification is the third highest out of 4 levels, and it is generally used either when there is limited, but not convincing, evidence for cancer in humans, or when there is convincing evidence for cancer in lab animals, but not both.
To learn more about the IARC classifications, see
Determining if Something Is a Carcinogen and
Known and Probable Human Carcinogens.
Joint FAO/WHO Expert Committee on Food Additives (JECFA)
JECFA is an international expert committee run jointly by the Food and Agriculture Organization (FAO) and the WHO. One of its main roles is to evaluate the safety of food additives. It considers all possible health impacts, including cancer.
JECFA assesses the risk that a specific type of harm (such as cancer) will occur in certain situations, considering how, how often, and how much people might be exposed to a food additive.
After completing a dietary exposure assessment, JECFA has concluded that “the evidence of an association between aspartame consumption and cancer in humans is not convincing.”
Based on current dietary exposure estimates, JECFA has concluded that dietary exposure to aspartame does not pose a health concern.