I have absolutely no worries about getting a brain tumor from using my cell phone. As I mentioned earlier, smoking is far, far, far, worse as cancer-causing habits go. Sensibly, I don't smoke, and sensibly in the absence of evidence of a direct connection between cell phone usage and brain tumors, I use my cell every day with no plans to put it down.
I am, however, very curious. The data collected and published so far pose as many questions as they answer. There seems to be enough of an increase in certain types of tumors among those who use cell phones to warrant asking more questions. No study to date has answered those very reasonable questions. Something is causing an increased incidence of gliomas among a subset of cell phone users. It'd be really dumb (or just cowardly) not to continue to probe what distinguishes that subset from everyone else and what the exact nature of the causation is. It may turn out that Wifi, not phones, is the problem, but we won't know until we uncover all the links.
To link being paranoid with asking reasonable questions is, well, unreasonable. This type of academic inquiry is exactly why we all have cell phones in the first place. Someone(s) kept asking questions in defiance of conventional wisdom and people's emotional attachment to their habits. That's what pure research is, asking and answering questions just so that you know the answer and understand exactly how it works--or doesn't. And usually pure research with no practical application in mind up front leads to wonderful things, like e-ink and iPhones!