As expected from a story we posted earlier this week, an agency linked to the World Health Organization (WHO) today declared aspartame, one of the world's most common synthetic sweeteners, a possible carcinogen.
For a food chemistry topic, the announcement got widespread coverage in the general press. While the International Agency for Research on Cancer (IARC), which made the announcement, has no regulatory power and its finding has plenty of qualifiers, consumers around the world no doubt took notice.
“Citing ‘limited evidence’ for carcinogenicity in humans, IARC classified aspartame as possibly carcinogenic to humans … and JECFA [the Joint WHO and Food and Agriculture Organization's Expert Committee on Food Additives], reaffirmed the acceptable daily intake of 40 mg/kg body weight,” the announcement said in its preamble.
That sounds somewhat contradictory, but it does explain an important distinction: There is a possible link between aspartame and cancer, but currently acceptable limits appear to be safe.
On a scale of 4, 1 being the most dangerous, aspartame was listed as 2B (earlier indications were that it would rate a 3). “The working group classified aspartame as possibly carcinogenic to humans (Group 2B) based on limited evidence for cancer in humans (for hepatocellular carcinoma, a type of liver cancer),” today’s report said. “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.
“There was also limited evidence for cancer in experimental animals. There was an increased incidence of tumours in two species, mouse and rat, of both sexes seen in three published studies. However, based on concerns over the study design, interpretation and reporting of data, the working group concluded that the evidence for cancer in experimental animals was limited.
“In addition, there was limited mechanistic evidence that aspartame exhibits key characteristics of carcinogens, based on consistent and coherent evidence that aspartame induces oxidative stress in experimental systems and suggestive evidence that aspartame induces chronic inflammation and alters cell proliferation, cell death and nutrient supply in experimental systems.”
Above comes from today’s IARC statement.
For perspective, IARC lists processed meat as “carcinogenic,” its highest level of concern — along with asbestos and other more likely substances, according to a Reuters news service report from earlier this week.
Another important qualifier is that IARC does not take into account is the quantity of a chemical required to make it a cancer hazard. According to JECFA data quoted in that earlier Reuters story, an adult weighing 132 pounds would have to drink between 12 and 36 cans of diet soda – depending on the amount of aspartame in the beverage – every day to be at risk.
Since 1981, JECFA has said aspartame is safe to consume within accepted daily limits. That view has been widely accepted by national regulators, including in the U.S. and Europe. Aspartame is used in products from diet sodas to chewing gum.
“Something the media and public miss ... is this statement that IARC makes in the preamble of its monographs: ‘A cancer hazard is an agent that is capable of causing cancer under some circumstances, while a cancer risk is an estimate of the carcinogenic effects expected from exposure to a cancer hazard,” Dan Wixted, extension support specialist, said in an email to Food Processing. “The distinction between hazard and risk is important, and the monographs identify cancer hazards even when risks are very low at current exposure levels.”
Finally, Alan Reilly, ex-chief executive of the Food Safety Authority of Ireland and adjunct professor at the Institute of Food and Health at University College Dublin, explains:
“Aspartame is an approved food additive and its safety has been evaluated by leading international agencies and scientific committees over many years. It has been found to be safe to use in foods. The most recent evaluation published today of its safety by the Joint Expert Committee on Food Additives … have reconfirmed that it is safe to use in foods at the approved levels.”