International Agency for Research on Cancer (IARC) and World Health Organisation (WHO) are set to declare artificial sweetener, Aspartame as a possible carcinogen for humans. This decision comes after a thorough research and assessment of all publishable evidence by external experts. The assessment does not say how much quantity should a person consume or what is a safe limit. This comes from a separate WHO expert committee on food additives known as the JECFA (Joint WHO and Food and Agriculture Organisation’s Expert Committee on Food Additives).  

Aspartame is an artificial sweetener which is 200 times more sweet than regular sugar and acts as a low-calorie alternative to regular sugar in diet beverages and foods. Aspartame is used in a range of products including Coca-Cola’s diet sodas, Mars’ Extra chewing gum and some Snapple drinks.

Similar rulings in the past have led to multiple lawsuits from consumers which forced the manufacturer to swap the ingredients to alternatives and recreate their recipes.

Since 1981, JECFA has said aspartame is safe to consume within accepted daily limits. For example, an adult weighing 60 kg (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. Its view has been widely shared by national regulators, including in the United States and Europe.

More than ninety countries have reviewed Aspartame and have found it safe for human consumption and have allowed its use.

An IARC spokesperson said both the IARC and JECFA committees' findings were confidential until July, but added they were "complementary", with IARC's conclusion representing "the first fundamental step to understand carcinogenicity". The additives committee "conducts risk assessment, which determines the probability of a specific type of harm (e.g. cancer) to occur under certain conditions and levels of exposure."

Regulators fear that both the processes going on at the same time would be confusing. Nozomi Tomita, an official from Japan's Ministry of Health, Labour and Welfare, wrote a letter to WHO's deputy director general, Zsuzsanna Jakab on March 27 saying, “We kindly ask both bodies to coordinate their efforts in reviewing aspartame to avoid any confusion or concerns among the public.”