Assessments of the health impacts of the non-sugar sweetener aspartame have officially been released by two agencies at the World Health Organisation after they reviewed thousands of international studies.

The sweetener was discovered in 1965 by American chemist James Schlatter and has been in use since the 1980’s, today found in dozens of food products and beverages.

As expected, and after reports were leaked a few weeks ago, aspartame has officially been classified as ”possibly carcinogenic” to humans. This classification is under the International Agency for Research on Cancer (IARC)’s 2B category – which essentially means there is ”limited evidence” that aspartame could possibly cause cancer.

To put it into perspective, the 2B category is the second lowest level of certainty, by which the IARC determines a substance’s potential hazard.

This means while smoking, excessive sun-bathing, drinking alcohol and radiation has been shown to cause cancer, and while eating too much red meat probably causes cancer, there is not enough evidence to suggest the same for aspartame.

Importantly, the second WHO agency that reviewed the scientific studies, namely the Joint Expert Committee on Food Additives (JECFA), reaffirmed that aspartame can still be consumed at reasonably high levels – i.e. the acceptable daily intake is set at 40 mg/kg body weight.

For example, with a can of diet soft drink containing 200 or 300 mg of aspartame, an adult weighing 70kg would need to consume more than 9–14 cans per day to exceed the acceptable daily intake, assuming no other intake from other food sources.

The Director of the Department of Nutrition and Food Safety at the WHO Dr. Francesco Branca says while safety is not a major concern at the doses which are commonly used, more and better studies would probably be needed.

Branca told the BBC you “shouldn’t have a concern” about an occasional diet drink or other product containing the sweetener, but that “high consumers” needed to be aware.

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It’s also important to note that the IARC classifications reflect the strength of scientific evidence as to whether an agent can cause cancer in humans, but they do not reflect the risk of developing cancer at a given exposure level – that’s the job of the second agency the JECFA.

Dr Moez Sanaa, WHO’s Head of the Standards and Scientific Advice on Food and Nutrition Unit said:

“JECFA also considered the evidence on cancer risk, in animal and human studies, and concluded that the evidence of an association between aspartame consumption and cancer in humans is not convincing.”

Overall, the Committee concluded that there was no convincing evidence from experimental animal or human data that aspartame has adverse effects after ingestion.

Aspartame is fully hydrolysed in the gastrointestinal tract into metabolites that are identical to those absorbed after consumption of common foods, and no aspartame enters the systemic circulation as such.

In short, a consistent association between aspartame consumption and a specific cancer type could not be demonstrated.

The bottom line? As with all things, moderation is key. And if you are consuming 9 or more cans of diet soda a day, you should probably cut down.

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