Wavelength matters - it's the difference between ionizing and non-ionizing. This article seems to indicate that not all of the non-ionizing radiation is harmle

Wavelength matters - it's the difference between ionizing and non-ionizing. This article seems to indicate that not all of the non-ionizing radiation is harmless. And heat itself is carcinogenic, yes -- drinking hot beverages is independently associated with a higher risk of mouth, throat, esophageal, and stomach cancer.