Cancer: if not electromagnetic radiation, then what?

Electromagnetic fields (EMFs) are everywhere, generated by power lines, mobile phones, Wi-Fi routers, and countless other technologies. This ubiquity has led to a persistent question: could non-ionising EMFs increase cancer risk? To answer that, it helps to start with some basic physics. Radiation exists on a spectrum. At the high-energy end is ionising radiation (like X-rays and gamma rays), which carries enough energy per photon to ionise molecules, break chemical bonds, and directly damage DNA. That kind of damage is a well-established pathway to cancer. Non-ionising radiation, such as radiofrequency (RF) signals used in wireless communication, operates very differently. Its photons carry far less energy, orders of magnitude too low to ionise atoms or break DNA bonds. That immediately rules out the most direct mechanism by which electromagnetic radiation can cause cancer. So what about indirect effects? One possibility is heating. High-intensity RF radiation can warm biological…