>cell phones

Well, as far as direct physical harms, yes, but as far as mental harms that translate to physical harms, the jury's still out:

'“Given that the increase in mental health issues was sharpest after 2011, Twenge believes it’s unlikely to be due to genetics or economic woes and more likely to be due to sudden cultural changes, such as shifts in how teens and young adults spend their time outside of work and school.'

https://www.apa.org/news/press/releases/2019/03/mental-healt...