Explained: What is aspartame and why WHO body may declare it 'possible carcinogen'

Aspartame, one of the most popular artificial sweeteners used in beverages and other consumable products across the world, is likely to be declared as “possibly carcinogenic to humans” this month by the International Agency for Research on Cancer (IARC), the World Health Organisation’s (WHO) cancer research body, reported Reuters quoting two unnamed inside sources.

What is Aspartame?

It is an artificial sweetener that is used as a sugar alternative because it has zero calories and no bitter aftertaste.

What products use aspartame?

The sweetener is used in a range of products like soft drinks, sodas, desserts, sugar-free juices, chewing gums, and drink mixes. Some of the easily-recognisable brands are Coca-Cola diet sodas, Mars’ Extra chewing gum, and Snapple drinks.

What are carcinogens?

Carcinogens are substances that can lead to cancer in humans. Some of the common carcinogens are tobacco, alcohol, asbestos, formaldehyde, ultraviolet rays, processed meat, engine exhaust, radon, and crispy brown foods.

Different levels of classification

The IARC has four different levels of classification – carcinogenic, probably carcinogenic, possibly carcinogenic and not classifiable. The classifications are decided based on the strength of the evidence that is available, rather than how dangerous a substance actually is.

Carcinogenic substances, the first level, include asbestos and processed meat – substances which have convincing evidence to show that they cause cancer.

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The second level of classification, the probably carcinogenic, refers to substances for which there is limited evidence of causing cancer in humans, stronger evidence of causing cancer in animals, or strong evidence that they have similar characteristics as other human carcinogens – like consumption of red meat.

The third level, possibly carcinogenic, include substances for which there is limited evidence of causing cancer in humans, sufficient evidence of causing cancer in animals, or strong evidence about the characteristics. The “radiofrequency electromagnetic fields” linked to using mobile phones falls in this category.

The final group – not classifiable – means there is not enough evidence to show that a substance is carcinogenic.

IARC’s role

The IARC ruling, based on the agency’s external experts, is intended to assess whether something is a potential hazard or not based on all the published evidence.

It does not prescribe how much of a product a person can safely consume.

This advice for consumers is given by another WHO expert committee on food additives — Joint WHO and Food and Agriculture Organisation’s Expert Committee on Food Additives (JECFA). National regulators then decide for their respective countries.

Since 1981, JECFA has said aspartame is safe to consume within accepted daily limits.

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Similar IARC rulings in the past for other substances had raised concerns among consumers about their use, led to lawsuits, and resulted in companies creating new recipes, and switching to alternative substances.

There also used to be confusion in the minds of consumers because IARC and JECFA used to give their rulings separately, with a gap of days or weeks.

Following representations from US and Japanese regulators to the international health body, IARC and JECFA are likely to announce their findings and rulings on aspartame the same day, on July 14.

Industry’s response

This ruling on aspartame by the IARC would be a severe blow to the food industry, which has dismissed the alarm. Industry bodies defend the use of the sweetener, saying that its use was declared safe by the regulatory bodies.

The IARC’s earlier decisions have faced criticism for sparking needless alarm over hard-to-avoid substances.

“IARC is not a food safety body and their review of aspartame is not scientifically comprehensive and is based heavily on widely discredited research,” Frances Hunt-Wood, secretary general of the International Sweeteners Association (ISA), said.

The association said it had “serious concerns with the IARC review, which may mislead consumers”.

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The International Council of Beverages Associations’ executive director Kate Loatman said public health authorities should be “deeply concerned” by the “leaked opinion”, and also warned it “could needlessly mislead consumers into consuming more sugar rather than choosing safe no- and low-sugar options”.

Aspartame is authorised for use globally by regulators who have reviewed all the available evidence, and food and beverage manufacturers have for several years defended their use of the sweetener.

The IARC said it had assessed 1,300 studies in its present review, and listing aspartame as a possible carcinogen is intended to motivate more research.

(With agency inputs)