Based on four epidemiological studies, the World Health Organization suggested that hot drink temperature seemed to increase the risk of esophageal cancer:
Studies in places such as China, the Islamic Republic of Iran, Turkey, and South America, where tea or maté is traditionally drunk very hot (at about 70 °C), found that the risk of oesophageal cancer increased with the temperature at which the beverage was drunk.
Animal studies also add limited evidence for the carcinogenicity of very hot water. IARC director Christopher Wild: ‘The proportion of oesophageal cancer cases that may be linked to drinking very hot beverages is not known…” Smoking and alcohol are more more potent epidemiological correlates of esophageal cancer, in any case.
‘How hot is “very hot”? The WHO’s temperature of 70 degrees Celsius is about 160 Fahrenheit, within the range that coffee shops typically serve. By the time your drink cools down, though, it’s probably below that. CNN reports that Americans and Europeans don’t usually drink beverages hot enough to be considered higher risk. If you want to be sure of your drink’s temperature, though, consider adding some milk, or ordering it at kids’ temperature.’