But there’s a huge public health crisis looming from one particular threat: EMR from cellular phones—both the radiation from the handsets and from the tower-based antennas carrying the signals—which studies have linked to development of brain tumors, genetic damage, and other exposure-related conditions.1-9 Yet the government and a well-funded cell phone industry media machine continue to mislead the unwary public about the dangers of a product used by billions of people. Most recently, a Danish epidemiological study announced to great fanfare the inaccurate conclusion that cell phone use is completely safe.10
It'd be wrong to say that there is no evidence of harm at all. In fact, the re-classification by the IARC came about in the first place because the Working Group contributing to the Interphone study acknowledged "limited evidence" of an increase in glioma (a type of tumour, commonly found in the brain) among phone users in one of the studies. In this study, which concluded in 2004, researchers found that participating phone owners who had used their handsets for calls for more than 30-minutes a day, over a period of ten years, had an increase incidence of glioma.
Of course, scientific seesawing like that doesn’t provide a lot of clarity or confidence for the 90 percent of American adults and roughly 80 percent of teens who report having a cell phone. So how concerned should you be about cell-phone radiation? Consumer Reports’ health and safety experts conducted a thorough review of the research and offer some guidance.
EWG believes that cell phone testing procedures should include cases and other accessories, whether supplied by the phone manufacturer or a third party. Since these cases and accessories have no other use and have the potential to influence the phone’s transmitting and receiving activity and the amount of radiation that a user might encounter, they fall within FCC’s authority.
In this frequency range, the interaction between matter and light is via the electric field component of light (totally different from how ionizing radiation messes you up). In particular, an oscillating electric field causes polar molecules to rotate or attempt to rotate, and the lag between the applied field and the response of the molecules manifests as dissipation—i.e. heating . This is the same dielectric heating which is the operating principle behind microwave ovens (which operate at 2450 MHz  similar to wifi). So if cell phones were to cause damage to tissue, the mechanism would be the same as what happens in a microwave oven—boiling the water in your head/body.
When you make a phone call, just flip the shielded front cover down when you put the phone against your head. It’s that simple. By keeping the shielded front cover closed while against any part of your body, a barrier is created to protect from a broad spectrum of potentially harmful cell phone radiation emissions, yet won’t affect signal quality. You can use your cell phone with a higher sense of safety by simply keeping the shielded flip cover between your body and radiation-emitting source.
In one type of study, called a case–control study, cell phone use is compared between people with these types of tumors and people without them. In another type of study, called a cohort study, a large group of people who do not have cancer at study entry is followed over time and the rate of these tumors in people who did and didn’t use cell phones is compared. Cancer incidence data can also be analyzed over time to see if the rates of brain tumors changed in large populations during the time that cell phone use increased dramatically. These studies have not shown clear evidence of a relationship between cell phone use and cancer. However, researchers have reported some statistically significant associations for certain subgroups of people.