Processed meat has been classed as ‘carcinogenic to humans’ by the World Health Organization (WHO).

It now joins tobacco smoking and asbestos in the Group 1 category which indicates “convincing evidence that the agent causes cancer”. 

The WHO said the decision was “based on sufficient evidence from epidemiological studies that eating processed meat causes colorectal cancer”. 

Stomach cancer was also linked to the consumption of processed meat, though the evidence was inconclusive.

However, the WHO stressed that the classification does not imply that processed meat, asbestos and tobacco smoking “are all equally dangerous” because the level of risk with each of these cancer causing agents differ.

The eating of red meat has also been linked to the likes of colorectal, pancreatic and prostate cancer, though the evidence is “limited”.

According to the WHO, the Global Burden of Disease Project – an independent academic research organisation – recently declared that some 34,000 cancer deaths annually across the world are linked to diets high in processed meat.

And the number could rise to 50,000 cancer deaths “if the reported associations [between red meat consumption and cancer] were proven to be causal”.

That contrasts with about 1 million cancer deaths per year globally due to tobacco smoking, 600,000 per year due to alcohol consumption, and more than 200,000 per year due to air pollution.

The report does not suggest that people should stop eating meat, or give a recommended daily amount, but claims that the risk of cancer “increases with the amount of meat consumed”.

The announcement has been criticised by science journalists, with Ed Yong writing for The Atlantic that the WHO’s classifications are based on “degree of evidence and not degree of risk”.

While Group 1 is labelled as ‘carcinogenic to humans’, Yong says this should be interpreted as meaning “we can be fairly sure that the things here have the potential” to be cancer-causing, not that they actually are.

“These classifications are not meant to convey how dangerous something is, just how certain we are that something is dangerous,” he writes. “But they’re presented with language that completely obfuscates that distinction.”