I did not say I believe the radiation is harmful. I said I believe it is POTENTIALLY harmful. Cell phones have only been in widespread use for what, 10 years? So theres no example to show what happens after, say, 20 years of cell phone use.
At any rate, I feel that a PC is a somewhat unique example in that its CPU is operating above 4GHz. Im not too familiar with other items that operate at such a frequency, even most PCs dont operate that fast.
The degree of exposure thats acceptable can be compared in relative terms. For example, I use a cell phone, but perhaps only a couple minutes a day. So, how would sitting in front of my 4.5GHz CPU, with no case around it, for a period of several hours a day, compare?