In 2016, the International Agency for Research on Cancer[ref]The International Agency for Research on Cancer is associated with the World Health Organization.[/ref] identified one carcinogen as “drinking very hot beverages above 65C (150 degrees Fahrenheit).”
This 2016 guidance has recently been validated by a study published in the International Journal of Cancer. Researchers studied over 50,000 people in Iran. The risk of developing throat cancer was nearly double in those who reported drinking very hot tea (at temperatures higher than 65C or 150 degrees Fahrenheit).
This makes sense. High temperatures are used to kill micro-organisms in organic matter. This process is called pasteurization, and is a great thing for killing microbes in a product you might wish to store for future consumption, such as milk. Need to ensure water is safe in a survival situation? Many folks keep a Water Purification Indicator (WAPI) in their emergency kit, which measures when water has been heated to 150 degrees for long enough to be safe.
So 150 degrees Fahrenheit is something of a magic number.
Do pasteurize food and water.
Don’t pasteurize your throat.
For what it’s worth, this correlates with other behaviors that damage body tissues, such as the link between excessive exposure to UV radiation (sun burn) and skin cancer.
As members of the Church of Jesus Christ, we already avoid caffeinated tea and coffee. In the spirit of reducing cancer risk and being heedful of counsel, feel free to put ice cubes in hot soup, milk in hot cocoa, and let the herbal tea steep for a spell before taking a sip.