People quit smoking but do not give up cell phones. They are more addictive than nicotine, period. Scientists once focused on tobacco smoke impact have now graduated to electromagnetic radiation research. Most studies suggest no harm, but some large ones are essentially retrospective studies comparing the habits of control groups vs. brain tumor groups. Somehow decade long recollections of folks with brain tumors may be a shaky foundation to build on.I say a simple way of settling the issue is a massive experiment where all cell phone users use the phone on the same side of the head. The answer will pop out by just looking at tumor location distribution in the future. A cognitive study correlated radiation exposure to one side of the head with longer average response times for the corresponding (i.e. opposite) hand than exposure on the other side. I have no bias for what the answer is, but I like such differential measurements more than interviews.
The massive experiment can be differential: in some countries people will use the phone on the right and in others on the left side of the head, according to the driving convention, for example. Countries with right side of the road driving will use the phone on the left side and keep the right hand free for shifting gears.
Agreement to do anything is hard. We have advertising, market forces, and coercion. None of these forces is welcome. Forget about people, let the phones run this experiment. What we need next is phones smart enough to only work on one side of our head.