The International Agency for Research on Cancer, or IARC, announced in a report published on Wednesday that drinking “very hot” beverages of any kind could potentially raise the cancer risk, and it classified them as “probably carcinogenic” to humans.
In particular, it cited countries including China, Iran and those in South America, where teas such as the bitter herbal infusion mate are traditionally drunk at extremely high temperatures – above 65 or 70 degrees Celsius (150 or 160 Fahrenheit) – considerably hotter than drinks would normally be served in cafes across North America and Europe.
Dana Loomis, deputy head of the IARC program that classifies carcinogens, said they began to look into a possible link after seeing unusually high rates of esophageal cancer in countries where drinking very hot beverages is common. He said that even at temperatures below 60 degrees Celsius (140 Fahrenheit), hot beverages can scald the skin, and that consuming drinks at even higher temperatures could be harmful.
Loomis said very hot beverages might cause a “thermal injury” in the throat that could eventually promote the growth of cancerous tumors, but that evidence was currently limited.
“Quitting smoking and reducing alcohol consumption are much more significant for reducing cancer risk than the temperature of what you’re drinking,” said Dr. Otis Brawley, chief medical officer of the American Cancer Society. Brawley said the cancer risk posed by drinking hot beverages was similar to that posed by eating pickled vegetables.
Some research suggests coffee may even lower the risk for certain types of cancer. A 2015 study found that frequent coffee drinkers (those who consumed four cups or more per day) had a 20% lower risk for developing malignant melanoma, the deadliest form of skin cancer. Decaf did not seem to offer the same protection. Additionally, a 2012 study found that people who drank more than three cups of coffee were 17% less likely to develop basal cell carcinoma, the most common form of skin cancer, compared with those who drank coffee less than once a month.