The World Health Organization (WHO) announced on June 15 that very hot drinks can probably cause esophageal cancer. The report was published in the The Lancet Oncology, stating that the risk of developing this disease increased with the temperature at which the drink was consumed.

The findings were part of a study by WHO and the International Agency for Research on Cancer (IARC) that sought to determine the carcinogenicity of maté, coffee, tea and other very hot beverages. Coffee, tea and maté themselves were declared to be non-carcinogenic but the piping hot temperature made them dangerous.

“These results suggest that drinking very hot beverages is one probable cause of esophageal cancer and that it is the temperature, rather than the drinks themselves, that appears to be responsible,” says Christopher Wild, the director of IARC.

very hot drinks

Very hot drinks can probably cause esophageal cancer. Credit: Watt Street

The researchers note that the results were based on limited evidence. Drinking very hot beverages is now classified in Group 2A, or probably carcinogenic to humans, of the IARC’s list of agents that pose cancer risk to humans. The esophageal cancer risk was high in South America, China, the Islamic Republic of Iran and Turkey, where drinks like mate or tea are taken at very high temperatures or 70 degrees Celsius.

“Smoking and alcohol drinking are major causes of esophageal cancer, particularly in many high-income countries,” adds Wild. “However, the majority of esophageal cancers occur in parts of Asia, South America, and East Africa, where regularly drinking very hot beverages is common and where the reasons for the high incidence of this cancer are not as well understood.”

The carcinogenicity of very hot water was inconclusive to animals. Drinking the aforementioned drinks at lower temperatures did not have carcinogenic effects on both animals and humans.

Researcher Mariana Stern tells people to enjoy their coffee or maté, but make sure they avoid very hot drinks. Stern is an associate professor of preventive medicine and urology at the Keck School of Medicine of University Of Southern California.