Is Morning Thunder Tea Harmful?

Thank you. I have read that drinking mate, especially very hot mate frequently (the latter word sometimes used to mean all day long ) can cause certain cancers. I bought some Morning Thunder (Celestial Seasonings) to drink rather than coffee, as coffee can give me the jitters. If I drank 16 oz a day (2 bags per 8 oz cup) at a warm temp, not hot, would this be dangerous? Studies have been done in South America linking heavy mate drinking to cancers of the mouth, esophagus, lung and bladder.