This is the best timeline

This is the traditional understanding of radiation interaction with the human body, and it presupposes the human body to be merely a bag of meat, subject only to the heating affects of radiation, which is overly-simplistic.

The human body is more akin to a bio-electric antenna, and the heating affects only scratch the surface (pun intended).

Here are some resources if you're open to learning more:

https://www.omniaradiationbalancer.com/pages/ionizing-vs-non-ionizing-radiation

https://www.omniaradiationbalancer.com/pages/effects-of-emf-on-the-body

https://bioinitiative.org/table-of-contents/

Truthfully, you don't want any of these things so close to your head- but BT headphones are preferable to holding your smartphone against your skull simply by virtue of raw power output. Either way though, you're literally microwaving your skull.

I personally only talk on my phone using the speaker. If I'm in public and have to take a call, I remove myself from the crowd to avoid being the proverbial rude douche blasting his conversation to the world.

To build on this:

If you have any doubt that wireless technologies (and wired, for that matter - but wireless is a massively nastier problem) have a negative affect on life- the book The Invisible Rainbow by Arthur Firstenberg details the history of human health issues coinciding with the rollout of electrical infrastructure technologies starting with the telegraph. It's also the primary culprit of what's killing the bees (though pesticides aren't helping either).

Additionally, power output isn't the only factor. These wireless technologies output frequencies that fuck with the harmonics of our mitochondria, ruining their ability to uptake oxygen --- exposure to even the lowest-powered wireless devices will eventually lead to issues (obviously some people are way more sensitive than others).

You can think of low-power harmonic frequencies similar to gently pushing someone on a swing; as long as the push is timed right, it still adds up and eventually that swing is going to be maxed out whether you're pushing hard or not.

Devices that seem woo-woo AF but work extremely well are SmartDOTS. They've enabled people previously rendered debilitated by EMF to live normal lives. If you'd like to learn more about them, I discovered them on the Health Hero Show ep. 76. They're very affordable.