Aspartame Classified as a Carcinogen… what does it mean?


Aspartame is a synthetic dipeptide artificial sweetener commonly used in food and beverage products. It is 180-200 times sweeter than sucrose and is widely used as a healthy replacement for sugar in soft drinks, confectionery, and medicine (Czarnecka et al. 2021). Aspartame was discovered in 1965 and was first regulated by FDA as a food additive in 1974; aspartame was recognized as a general-purpose sweetener in 1996 (Food and Drug Administration (FDA) 2023).

Despite the widespread use of aspartame, concerns have been raised about its safety and potential carcinogenicity for many years. The International Agency for Research on Cancer (IARC) recently classified aspartame as possibly carcinogenic to humans (Group 2B) based on limited evidence that it poses a risk to humans forhepatocellular carcinoma, a type of liver cancer (International Agency for Research and Cancer (IARC) 2023). The IARC working group identified three studies that exhibited a positive association between artificially sweetened beverages and liver cancer risk (Jones et al. 2022; McCullough et al. 2022; Gnudi 2023), as well as three animal studies that showed increased tumor incidence in mice and rats in both sexes (Soffritti et al. 2006; Soffritti et al. 2007; Soffritti et al. 2010; Joint FAO/WHO Expert Committee on Food Additives (JECFA) 2023; Riboli et al. 2023).

In 2006, 2007, and 2010, the Ramazzini Institute (RI) in Bologna, Italy reported aspartame intake was associated with increased incidence of malignant tumors, lymphomas, leukemia, lung cancer, liver cancer, etc. (Soffritti et al. 2006; Soffritti et al. 2007; Soffritti et al. 2010). However, these studies were conducted by the same laboratory and have been criticized due to deficiencies in their protocols and reporting practics. Most studies, including two-year rodent cancer studies and the National Toxicology Program’s nine-month studies on genetically altered mice, showed no evidence of carcinogenic activity of aspartame (National Toxicology Program (NTP) 2005; Pavanello et al. 2023).

Currently, both FDA and The European Food Safety Authority (EFSA) recognize aspartame as safe (European Food Safety Authority (EFSA) 2023; Food and Drug Administration (FDA) 2023). The FDA has set the Acceptable Daily Intake (ADI) for aspartame at 50 mg/kg of body weight per day, and the European Food Safety Administration (EFSA) recommends a slightly lower ADI at 40 mg/kg/day. According to EFSA, an adult weighing 60 kg (132 lb) would have to drink 12 cans of diet soft drinks at maximum permitted levels of aspartame use every day to reach the ADI of 40mg/kg/day. However, in reality, aspartame levels in soft drinks can be 3 to 6 times less than the maximum permitted levels, and in order to reach the ADI, one needs to drink 36 cans or more of soft drinks (American Cancer Society 2023; Blum 2023).

Even though IARC serves as a group which only focuses on the hazard identification step in a risk assessment and that they don’t consider dose in their analyses, their decisions often stimulate regulatory action, or they can alter the views of the public.  Thus, the updated classification could have a profound impact on the non-sugar sweeteners industry. There have already been a number of personal injury litigation matters filed regarding aspartame. One plaintiff claimed that after he started consuming aspartame, he suffered from “neurological and physical ailments, including tachycardia, dizziness, anxiety, panic attacks, blurred vision, inability to concentrate, loss of memory, and shooting pains in his left arm.” Another plaintiff claimed Altria failed to warn consumers of the possible health risks associated with aspartame. Neither case lasted long, due to the limited evidence on the toxicological effect of aspartame (Ellender 2005). In spite of the fact that IARC did not claim to present a risk assessment, its updated categorization of aspartame is likely to result in a new wave of litigation in the United States.


How Paustenbach & Associates Can Help

Litigation associated with aspartame is likely to increase in the coming years. The only way to ensure that the public and juries reach sound decisions about aspartame is to conduct a proper health risk assessment so that the importance of exposure and cancer potency are brought together so that “risk” can be calculated. In the case of aspartame, we believe, based on various approaches to the risk assessment, that this chemical would be considered safe for the vast majority of Americans who ingest the various consumer products.  Scientists at Paustenbach & Associates have over 55 years of experience in conducting many risk assessments of orally ingested chemicals, including diacetyl and potassium sorbate, and many food additives, as well as pesticides.

We have offered testimony in more than 400 depositions and 30+ trials over the years where we presented our risk analyses. In the cases for which we were retained, we applied exposure science and the health risk assessment methodology embraced by the National Academies of Science to characterize the possible risks. Over the years, we have conducted more than 1,000 risk assessments. Please contact Grayson Abele for more information regarding our capabilities at or 303-598-0998.



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Blum D. 2023. The W.H.O. Says Aspartame is “Possibly Carcinogenic.” What Does That Mean?  The New York Times. July 13, 2023. 1-2.

Czarnecka K, Pilarz A, Rogut A, Maj P, Szymanska J, Olejnik L, et al. 2021. Aspartame-True or False? Narrative Review of Safety Analysis of General Use in Products. Nutrients. 13: 1-17.

Ellender D. 2005. A Class-Action Lawsuit against Aspartame Manufacturers: A Realistic Possibility or Just a Sweet Dream for Tort Lawyers. Recent University Law Review. 18: 179-208.

European Food Safety Authority (EFSA). 2023. Aspartame. European Food Safety Authority.

Food and Drug Administration (FDA). 2023. Aspartame and Other Sweeteners in Food. Food and Drug Administration.

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National Toxicology Program (NTP). 2005. NTP report on the toxicology studies of aspartame (CAS No. 22839-47-0) in genetically modified (FVB Tg.AC hemizygous) and B6.129-Cdkn2atm1Rdp (N2) deficient mice and carcinogenicity studies of aspartame in genetically modified [B6.129-Trp53tm1Brd (N5) haploinsufficient] mice (feed studies). Research Triangle Park, NC: National Toxicology Program, U. S. Department of Health and Human Services. 1-225

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Riboli E, Beland FA, Lachenmeier DW, Marques MM, Phillips DH, Schernhammer E, et al. 2023. Carcinogenicity of aspartame, methyleugenol, and isoeugenol. Lancet Oncology.

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