That may be true today. But some experts have grave concerns about the types of low-intensity radiation our wireless devices produce. “We have animal studies suggesting even low-level exposures to the kind of radio wave radiation associated with Wi-Fi could have a variety of negative health effects,” says Joel Moskowitz, director of the Center for Family and Community Health at the University of California, Berkeley. (Moskowitz has collected much of that research here.)
ShieldMe  On the ShieldMe site is a message from Wireless Connection CEO Rose Vitale addressing issues with the cellphone industry and she makes some good points.  As far as how ShieldMe works she states, " Our ShieldMe cases help deflect up to 99% of the harmful EMF, RF or microwave radiation emitted from a cellphone while carrying around or when on a call." The demonstration of the SheildMe case shows levels that like the "EMF protection cellphone cases" is many many times higher than levels EMF expert Larry Gust follows as a certified building biologist.   
Everyone should be sleeping at bed time, and WiFi signal may interferes with the brain during sleep, so it is a good idea to turn it off before going to bed. This allows the body to rest more deeply. By turning it off at night, you are effectively cutting down exposure by 33%. (Aside from the WiFi reduction, many security experts also recommend turning off your internet when not using it).

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.