I think that if something has any hint of a risk, there is a risk. You don't really know if something is harmful to you till perhaps 5, 10 or 15 years down the road. By the time you find out, it is too late. There are saying prolonged cellphone use can give you brain cancer. The same number of studies indicate that it isn't true. So are you going to take a risk for not using a wired (not Bluetooth) hands-free?
A hint of a risk is not a risk. A risk is a measurable potential for something to happen. A hint of a risk is a fearful mind looking at random data and seeing what it wants to see (ie something to fear).
If cellphones caused brain cancer, we wouldn't have to wait 5, 10, 15 years. There would be many "canary in the coal mine" cases - people who developed brain tumours due to excessive cellphone use in a short period of time. This would show as a spike in brain cancer rates. So far, this has not been observed. So, as of now, it appears that cellphones do not cause brain cancer. It should probably be noted, as well, that people
have been using cellphones for at least ten years.
The situation is even more clear cut for hydro lines. Hydro substations and power lines have existed for decades. If there was any issue with them, we would see broad corridors of brain cancer around them. This has also not been observed.
It should probably be noted that while you sit at your computer, there are thousands of unseen energy waves passing through you: radio waves, microwave transmissions, cosmic rays, etc, etc. Keeping your cellphone away from your head is not stopping all of the transmissions from all the other cellphones around you from passing through your brain. And, really, if you are that concerned, putting your cellphone transmitter near your groin is just going to move the cancer to another, perhaps equally valuable place.