Yes, there are problems associated with long-term cell phone usage, because the brain is under constant assault from microwaves. It would be like a person putting their head into a microwave and pushing the on button for 30 minutes every day. The brain is bound to be different than it was before.
I believe there are some problems associated with long-term cell phone usage. I believe cell phones have greatly impacted our social interactions and not necessarily in a good way. On the medical end many believe that these devices can cause cancer or make it more likely which is usually a problem after extended use.
No, the people in this society today have been using cell phones everyday for going on about ten years now, and there has not been any things that cause any problems from using one everyday, besides maybe not getting the same amount of work done that we used to do.
There seems to be no long term damage with cell phone usage. There have been many tests, most are inconclusive, but of the ones that did make scientific journals, none are saying that cell phone usage is causing physical damage to people. This was a myth born in the 1990s.
There has been some scientific research done on the effects of long term cell phone research, and so far the findings have been inconclusive. Considering that we've had cell phones for close to 30 years, and inconclusive is the best we can come up with after all that time, I'm going to assume they're safe.