[endorphone]

We know, unequivocally, that high-power radio waves in certain frequency bands can cause tissue heating (e.g. it isn't ionizing radiation like what you see in UV and beyond, where photons have enough energy to displace electrons and cause unfortunate events, but just that it slightly increases the energy state). This particular study put very high power outputs right beside rats from gestation in the womb to their death, and paradoxically saw that their average lifespan was increased, though there were other cited ailments (which could be simply due to higher lifespan tissue temperature). Ideally you don't have a cell transmitter right beside you from birth to death.

The average exposure is many magnitudes lower. And given that heating is the only scientifically possible outcome, it is a pretty well studied area, but we should surely keep doing more.