Could cell-phone radiation cause cancer?
No, cell phone use does not cause cancer. We know it doesn't cause cancer because:
- There is no plausible mechanism.
- Animal studies show no effect.
- Human studies that get non-null results don't show a dose-response.
Doing these cell-phone studies with human subjects makes as much sense as doing studies to figure out whether I can cause my neighbors to get cancer by thinking evil thoughts about them. In both cases, there is no remotely plausible physical mechanism for the direct effect as postulated. The only reason to do the cell-phone study and not to do the evil-thoughts study is that the former appeals deeply to people's folk beliefs, which have been built up from decades of movies and comic books where "radiation" causes magical effects.
Some studies with human subjects give positive results and some give null results. This should not surprise us. The studies are measuring the relative sizes of their random and systematic errors. In the studies where they succeed in getting their random errors down to a smaller level than their systematic errors, they will measure either a positive or a negative correlation with cancer. In the ones where they succeed in getting their systematic errors down to a smaller level than their random errors, they will get a null result.
This wiki article covers most bases.
In conclusion, the connection to cancer is unclear from controlled studies. There is some surface heat that can be generated when next to the head, of the order of 2 watts but not clear how bad that is. Sunbathing hatless heats by many more watts (1300/m^2). Cancer of the skin has been connected with the sun due to ultraviolet radiation ( cell phones are microwave range), but not the head.
If I were a man I would avoid hanging a cell phone next to the family jewels, because heat is deleterious to fertility:).
It could due to multi-photon effects. It's already known that cell phones cause changes to brain activity. This was widely reported in the news. For example see "Cell Phone Study: Cell Ups Brain Activity". As of now, this is an unknown effect. So it might be associated with something that causes cancer.
(I'm not worrying.)