Earlier this month, The International Agency for Research on Cancer (IARC) classified the popular non-sugar sweetener aspartame as “possibly” carcinogenic to humans which has, understandably, raised concerns within industry and left a taste in consumers’ mouths that was far less sweet than they were used to.
IARC, who “classify a substance according to the strength of the evidence that the substance can cause cancer”, stated that there was [some, albeit] limited experimental evidence to support this classification (in animals) and little insight into possible mechanisms for causing cancer.
So...what does this actually mean?
Well, IARC identify the preventable causes of human cancers, focusing on three different areas:
- Studies on cancer in exposed humans
- Studies on cancer in experimental animals
- Mechanistic studies (i.e. does it act like known carcinogens?)
Once the data have been assessed, compounds are categorised into four possible hazard categories:
- Group 1: carcinogenic to humans
- Group 2A: probably carcinogenic to humans
- Group 2B: possibly carcinogenic to humans
- Group 3: not classifiable
Aspartame has been classified in Group 2B based on an association between hepatocellular carcinoma, a form of liver cancer, with artificially-sweetened drink consumption. But it should be noted that IARC’s cancer classifications indicate only that a substance could possess carcinogenic potential, but not the level of cancer risk associated with different sources and levels of exposure. Other members of the “possibly” carcinogenic category include such disparate entities as engine exhaust fumes and lead, as well as aloe vera and some pickled vegetables.
In response to this recent IARC classification, The Joint FAO/WHO (Food and Agriculture Organisation/World Health Organisation) Expert Committee on Food and Additives (JECFA), who conduct risk assessments and consider levels of exposure, have released a statement concluding that the new classification “indicated no sufficient reason to change the previously established Acceptable Daily Intake (ADI) of 40 mg/kg bw”, with the Committee reaffirming that it is safe for a person to consume within this limit daily for life. This ADI has been supported by other Expert Groups such as the European Food Safety Authority (EFSA), who have conducted their own comprehensive risk assessment of aspartame.
And in real terms...?
So how many fizzy drinks would you have to consume to exceed the established safe limit? Well, if you are an adult who weighs around 70kg, you would have to consume between 9-14 cans of sweet fizzy drinks daily (assuming your drink contains around 200-300 mg of aspartame) to exceed the upper safety limit of 40 mg/kg bw. For reference, a Coke Zero contains just 87 mg of aspartame. Now, we don’t know about you, but drinking 14 cans of fizzy diet drink is not something we accomplish daily.
The WHO reported that IARC and JECFA “conducted independent but complementary reviews”, however it is clear to see why this has left the general public confused, and industry feeling a JECFA review of aspartame would be more relevant. This leads us to the conclusion of this story: expert risk assessment is essential for putting health hazards in an appropriate context.
Now we know what you’re thinking, I wish there was an analogy to solidify my understanding of the differences between hazard and risk…well don’t worry, we have you covered. If one of our toxicologists came into the office one morning and warned colleagues to watch out for sharks today, this might cause some confusion. Why you ask? Sharks are dangerous and definitely a hazard, but the risk of being attacked by a monstrous great white on Wallington High Street is, to put it technically, slim. If there is no exposure to the hazard, then there can be no risk. Once again, this is why careful and expert risk assessment is paramount to both identifying hazards and evaluating potential human exposure.