Very hot drinks probably cause cancer, an agency of the World Health Organisation (WHO) has said.
The International Agency for Research on Cancer (IARC) said very hot drinks (65C and over) probably cause cancer of the oesophagus.
But it ruled there was “no conclusive evidence” that coffee itself causes cancer or that mate - a caffeine-rich drink typically enjoyed in South American countries - causes cancer at temperatures that are not very hot.
Dr Christopher Wild, director of IARC, said: “These results suggest that drinking very hot beverages is one probable cause of oesophageal cancer and that it is the temperature, rather than the drinks themselves, that appears to be responsible.”
In 1991, IARC said that coffee is linked to bladder cancer. In its new evaluation of more than 500 studies, it found that coffee drinking had no carcinogenic effects for cancers of the pancreas, female breast, and prostate.
Reduced risks were seen for cancers of the liver and womb. For more than 20 other cancers, the evidence was inadequate to enable a conclusion to be made.
It said: “The evidence that drinking coffee might cause bladder cancer, which was limited in the previous evaluation, has become weaker, and it is no longer possible to determine whether drinking coffee causes bladder cancer.”
However, IARC said it could not prove that coffee was “safe”, only that existing scientific data supports the theory that coffee is unlikely to cause certain cancers.
Dr Rachel Thompson, head of research interpretation at the World Cancer Research Fund, said: “This new research, which shows that drinking very hot drinks can increase the risk of oesophageal cancer, is very interesting.
“Our own research analysis found similar evidence for people drinking the South American herbal tea, mate, scalding hot through a metal straw. It is therefore not surprising that this is seen to be reflected in other beverages that are drunk at very high temperatures. We will be carrying out further research analysis into hot beverages in the future.
“To all the tea lovers out there, these new findings don’t mean that you can no longer enjoy hot drinks. It is the very hot temperatures that have been identified as a cancer risk and so, when drinking tea or other hot drinks, just let it cool down for a few minutes especially if you’re not adding any milk.”
National Coffee Association (NCA) president Bill Murray said: “This finding is great news and highly significant for coffee drinkers and confirms evidence from an avalanche of studies by highly respected and independent scientists.”
Casey Dunlop, health information officer at Cancer Research UK, said: “Most people in the UK don’t consume drinks at the temperatures considered in this research, although very hot tea is a popular drink in Middle Eastern and other countries.
“There is some evidence that drinking very hot drinks over 65C may increase the risk of oesophageal (food pipe) cancer.
“So as long as you let your drink cool down a bit before you drink it, you’re unlikely to be much at risk.”
On coffee, she added: “The reassuring news for coffee drinkers is that coffee is unlikely to increase cancer risk. This decision from IARC reflects a large body of evidence that consistently shows coffee does not increase the risk of cancer.”