ISLAMABAD: In a review published by the International Agency for Research on Cancer, the cancer agency of the World Health Organization, drinking very hot beverages was classified as "probably carcinogenic to humans."
More specifically, the review by a panel of global experts stated that drinking beverages at temperatures above 65 degrees Celsius -- 149 degrees Fahrenheit -- could cause people to develop cancer of their esophagus, the eighth most common form of cancer worldwide. Drinking tea, coffee or other hot beverages at this temperature can cause significant scald burns in the esophagus when they're consumed and has previously been linked to an increased cancer risk in this part of the body.
Warm beverages are not typically consumed this hot in Europe and North America but are commonly served at, or above, this temperature in regions such as South America, the Middle East and East Africa -- particularly when drinking teas. It's hotter than water coming out of sink faucets, which is typically no higher than about 140 degrees Fahrenheit (60 degrees Celsius), but not as hot as boiling water. Water boils at 100 degrees Celsius, or 212 degrees Fahrenheit.
The 65-degree Celsius temperature noted by the cancer research agency is enough to burn your tongue, and and according to the American Burn Association, skin contact with a liquid this hot can result in almost instantaneous burns if prolonged.
The findings come after a group of 23 international scientists analyzed all available data on the carcinogenicity of coffee, maté -- a leaf infusion consumed commonly in South America and other regions -- and a range of other hot beverages, including tea. They decided that drinks consumed at very hot temperatures were linked to cancer of the esophagus in humans.
The new classification puts consuming very hot drinks in the same risk group as exposure to substances such as lead, gasoline and exhaust fumes, which are also classified as "possibly carcinogenic" by the agency. Use of talcum powder on the perineal or anal regions of the body is also within this category.
Evidence for the findings was limited, but studies in China, Iran, Turkey and South America found positive associations between the risk of this form of cancer and temperatures at which drinks were consumed. Forms of tea, including the leaf infusion maté, are typically drunk at extremely high temperatures, above 158 degrees Fahrenheit (70 degrees Celsius) in these regions, according to the agency.
"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," said Dr. Christopher Wild, director of the International Agency for Research on Cancer.
Consumers in industrialized countries can stay calm, as they typically drink their beverages with less heat. "This is about 10 degrees [Celsius] higher than people in North America [and Europe] like their coffee," said Dana Loomis, deputy head of the monographs section at the cancer research agency that led the review.
Individually, coffee and maté did not have conclusive evidence for any cancer-causing effects when served at cool or warm temperatures, meaning the drinks themselves were not classified as carcinogenic.
Esophageal cancer was responsible for approximately 400,000 recorded deaths worldwide in 2012, about 5% of all cancer deaths.
Though smoking and drinking alcohol are major causes of esophageal cancer, particularly in high-income countries, the majority of cases globally for this form of cancer occur in parts of Asia, South America and East Africa.
"[Here], drinking very hot beverages is common, and the reasons for this high incidence of this cancer are not well-understood," Wild said.
The Tea Advisory Panel in the United Kingdom has responded to the classification by highlighting that tea is drunk at lower temperatures in the UK and that most people add milk.
"Tea drinkers in the UK can continue to enjoy tea in the traditional way with a drop of milk, which ensures that the temperature of tea sits within safe limits," said the panel's Tim Bond. "A study by UK burns doctors found that a cup of tea with 10 milliliters of milk cooled to less than 65 degrees Celsius within five minutes."