Are CellPhones Harmful ?

I was thinking from long time about this question. Had discuss to few doctors also for my curiosity... No convincing answer from anybody ! The fact is that whenever new technology / new medicines get introduced in market they are tested only for few months / few years at the most. The health community always takes these tests as a proof of harmlessness. But unfortunately nobody knows how new medicines or new technologies affect us over the span of 10, 30, 50 years or how they will affect over the span of few generations.

I found few links related research on effects of cell phones on human health. Some of the findings are -

1. During 1994-98 The studies related to brain tumor and brain cancer were conducted in Sweden, Newyork and Boston containing 233,469 and 782 brain cancer patients in three different experiments. But they found absolutely no correlation with cell phone usage. In 2006, Danish scientists also conducted similar study on large number of people. It also showed that mobile phones do not increase any cancer risks. However in a similar experiment on animals it was found that low levels of radio frequencies can accelerate development of cancer in laboratory rats. This is a worrisome fact.
   
2. Some Swedish researchers had studied effects microwave radiations on rat brains. It showed that the microwaves reduce the blood-brain barrier. This leads to passing of some unintended proteins and free radicals to pass from blood into brain cells. However it is still unknown that whether this research is relevant for radio frequencies used by cellphones.
3. Some research at university of athens has shown that fruit flies' reproduction capacity got affected by exposure to pulsed radiation for 5 days. Even some study also showed damaged DNA fragments.
4. However some clear indications of effect on sleep because of radio frequency exposure has been found. Some of these experiments showed quite ironically that sleep actually improved !
5. The studies on people living withing 300 meters of showed many symptoms like Fatigue, headache, sleep disruption and loss of memory. This study was made in many countries. However similar study conducted at University of Essex has shown absence of such effects among volunteers !
6. Recently (in 2009) one study has shown that the people who keep cell phone in their small pouch tied to their waste have shown reduction in density of pelvis bones. But in this experiment also the difference in bone densities was not significantly large.
   

Finally, I could conclude that there is no clearcut indication of good / bad effects of cellphone usage on human being yet. But there is a abundant possibility that there can be some effects which requires further study.