The highest typical daily exposure, according to a study of 2009, came from cellphone base stations, cellphones and DECT cordless phones, with the highest exposure locations in trains, airports and buses. The typical background power of electromagnetic fields in the home can vary from zero to 5 milliwatts per meter squared. Long-term effects of these electromagnetic fields on human and animal health are still unknown.
If you’re thinking of buying a phone case with ‘radiation blocking material’ believing it will reduce radiation, you should know this: Phones have automatic power control, such cases act as shields and make the phone work harder, transmitting more power, increasing heat and reducing battery life, The incoming signal to the phone will also be reduced so your phone may not work in areas of poor signal.
Acute exposure of rabbits to WIFI increased heart frequency (+22%) and arterial blood pressure (+14%). Moreover, analysis of ECG revealed that WIFI induced a combined increase of PR and QT intervals. By contrast, the same exposure failed to alter maximum amplitude and P waves. After intravenously injection of dopamine (0.50 ml/kg) and epinephrine (0.50 ml/kg) under acute exposure to RF we found that, WIFI alter catecholamines (dopamine, epinephrine) action on heart variability and blood pressure compared to control.
Research on glioma brain tumors shows the average latency period is 20-30 years.  Although cell phones were introduced in 1983, it was not until 2003 that over 50% of the US population had a wireless subscription, so the 20 year mark for mass cell phone use has not yet been reached.   The May 17, 2010 INTERPHONE study, the largest study ever to examine possible links between cell phones and brain tumors, concluded that overall there was "no increase in risk" for glioma or meningioma brain tumors,  but the average user in the study had less than eight years of cell phone exposure.  In his review of the INTERPHONE study results, Dr. Rodolfo Saracci stated that "none of today’s established carcinogens, including tobacco, could have been firmly identified as increasing risk in the first 10 years or so since first exposure." 
I had a wireless router installed about a month ago, since then I have had trouble sleeping and also it was like something was inflaming my brain (don’t know how else to describe it). I stumbled onto the discussion about WiFi and problems associated with it and decided to turn off the WiFi on my router and just go with a wired connection. Instantly the pressure on brain was gone, its like my brain began to relax once the wireless was off. How can they say there is no evidence?
Because of inconsistent findings from epidemiologic studies in humans and the lack of clear data from previous experimental studies in animals, in 1999 the Food and Drug Administration nominated radiofrequency radiation exposure associated with cell phone exposures for study in animal models by the U.S. National Toxicology Program (NTP), an interagency program that coordinates toxicology research and testing across the U.S. Department of Health and Human Services and is headquartered at the National Institute of Environmental Health Sciences, part of NIH.
Radiofrequency radiation is a form of electromagnetic radiation. Electromagnetic radiation can be categorized into two types: ionizing (e.g., x-rays, radon, and cosmic rays) and non-ionizing (e.g., radiofrequency and extremely low frequency, or power frequency). Electromagnetic radiation is defined according to its wavelength and frequency, which is the number of cycles of a wave that pass a reference point per second. Electromagnetic frequencies are described in units called hertz (Hz).
This study was an in-vitro pilot study which established the effect of radiofrequency radiation from 2.4 GHz laptop antenna on human semen. A test of significance between results of semen parameters using Mann-Whitney U- test at 0.05 level of significance showed a significant effect of RFR exposure on sperm concentration, motility and morphology grading.
Cancer is the obvious start. An early concern with mobile technology was clusters of the disease around those living near phone masts. One study in Israel found a 4.5-fold increase in cancers of all kinds in the immediate vicinity of a mast (Int. J. Cancer Prev., 2004). In 2009, a Korean team of researchers carried out a pool analysis of the results of 23 studies, which involved almost 38,000 subjects.