A lesson on radiation flux.
Every second of every day of your life, 650 trillion neutrinos from solar radiation flux pass through your body. Over the course of a roughly 80 year lifetime, only one of those many trillions upon trillions upon trillions of neutrinos will actually interact with one of the atoms in your body. Neutrinos barely interact with matter at all, so even though there's a huge stream of them passing through you constantly, they don't do a thing to you.
Huge radiation flux, zero net biological effect.
Now let's look at the other extreme end of the spectrum. If an astronaut stood on the surface of Io, which is Jupiter's innermost major moon, the radiation flux from Jupiter's magnetic field would give that astronaut a lethal dose of radiation in less than an hour. Jupiter's magnetic field carries a huge flux of charged particles travelling at near-relativistic velocities, and when they collide with the atoms in your body, they do it with a vengeance, and they cause a great deal of damage.
Huge radiation flux, almost immediately lethal biological effect.
What about cell phone radiation? Wi-Fi and LTE are both a very low energy flux of very low wavelength microwave radiation. Everything on the electromagnetic spectrum below X-rays - ultraviolet, visible light, infrared, microwaves, and radio waves - is non-ionising radiation. Non-ionising radiation doesn't knock electrons out of their nominal orbits (which is what X-rays tend to do) or cause state changes in the protons or neutrons in an atomic nucleus (which is what gamma rays tend to do).
When you have a very low energy flux of low wavelength, non-ionising radiation, it does... wait for it... absolutely nothing to biological tissues. You could wear an Apple Watch on your wrist for 100,000 years and never develop cancer from the radiation it emits.
In other words: tiny radiation flux, zero net biological effect.
Non-ionising microwave radiation can cause damage to biological tissue - if the radiation flux is powerful enough. This is why standing right next to an active cell tower (and I mean right next to the antenna, not on the street below) is generally a Bad Idea. However, this radiation flux is several orders of magnitude more powerful than any handheld or wristworn device can ever emit.
TL;DR: Wi-Fi and LTE don't cause any biological harm whatsoever. The energy emitted is too low, and the radiation wavelength is both very long and non-ionising, all of which contribute to a radiation flux that simply passes straight through you with no effect at all - just like the 100 quadrillion solar neutrinos that shot through you in the time it took to read this post.