It is not the power of 5G (or other EMF) that is necessarily important. It is the frequency which is important. Since the frequency can activate voltage gated calcium channels, the ion flux through these channels magnifies the tiny initiating signal. Safety evaluation by dotgov only takes into account power (i.e. heating of tissues)… It completely ignores any other effects.

Electromagnetic fields act via voltage-gated calcium channels to produce beneficial or adverse effects

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3780531/

Microwave EMFs produce neuropsychiatric effects

https://www.sciencedirect.com/science/article/pii/S0891061815000599