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The long list of cancer-causing agents is getting longer. Smoking, exposure to UV radiation from the sun; air pollution are known culprits on the list. However, the World Health Organisation (WHO) has added hot drinks like coffee, tea and maté to the list.
The group’s International Agency for Research on Cancer (IARC), made up of 23 scientists from 10 countries, reviewed around 1,000 studies that investigated a connection between high-temperature beverages and their potential link to the disease.
Based on the available evidence, they conclude that drinking very hot beverages, which they defined as anything above 65C (149F), is linked to higher risk of cancer of the esophagus. The conclusion is published in Lancet Oncology.
Their studies found higher rates of esophageal cancer among people who drank extremely hot tea or coffee compared to those who consumed their drinks at lower temperatures. The link to cancer remained strong even after they adjusted for things like smoking and other possible cancer risk factors.
Animal studies also seem to hint that even very hot water can increase the risk of this type of cancer, presumably because the temperature scalds delicate tissues in the esophagus; that damage may then trigger more rapid turnover of the cells, which can in some cases lead to out-of-control malignant growth.
The group of probable cancer-causing agents in people includes 79 substances, most recently red and processed meat, fried foods, DDT and the human papillomavirus (which is linked to cervical cancer).
The report also concludes, however, that there isn’t adequate evidence to classify coffee itself as a carcinogen. Against what was thought in the past, Dana Loomis, deputy head of the IARC said “the available scientific evidence base is much larger and stronger” because recent studies support the benefits of coffee in lowering risk of cancer in certain parts of the body.
But for 20 other types of the disease, the evidence isn’t strong enough to suggest either a benefit or risk, so the IARC is changing the designation to “inadequate evidence for carcinogenicity of coffee drinking overall.”
People who drink more coffee seem to have lower rates of certain cancers, including liver and endometrial cancers. But Dr. Otis Brawley, chief medical and scientific officer at the American Cancer Society, says “that’s not where hot beverages hit. Hot beverages hit the mouth, throat, esophagus and stomach.” So that means that even though coffee may be hot, as long as it’s not too hot, there doesn’t seem to be evidence linking coffee to higher risks of cancer other than esophageal cancer.
In the studies the group reviewed, there seemed to be an increased risk of esophageal cancer only when people drank very hot beverages, usually above 149F.
Dr. Brawley however adds that except for people with Barrett’s esophagus, a condition that often precedes esophageal cancer, the risk from the higher temperature drinks is much smaller than the risk from other, more common risk behaviors.
TIME quoted him as saying: “I would say anybody who drinks alcohol shouldn’t even worry about this because alcohol is far more of a cancer-causer than coffee or hot drinks. Anybody who smokes cigarettes also shouldn’t worry about this because cigarettes are a far greater cause of cancer than alcohol.”