Morbidity and mortality among study participants who have brain cancer. Gliomas are particularly difficult to study, for example, because of their high death rate and the short survival of people who develop these tumors. Patients who survive initial treatment are often impaired, which may affect their responses to questions. Furthermore, for people who have died, next-of-kin are often less familiar with the cell phone use patterns of their deceased family member and may not accurately describe their patterns of use to an interviewer.
The device comes in a variety of forms ranging from the $39 Aries Shield ("a silicon based micro processor that ... decomposes oscillations of electromagnetic fields") to the $249 Aires Defender Utility (which "has two next generation 9 core silicon based micro processor (sic) that provide universal protection from electromagnetic smog of the broadband frequencies").
None of the three cases contain metallic parts, which are known to affect SAR, but all increased the user’s radiation exposure. The effect on radiation exposure would likely vary with each of the hundreds of cases on the market, and each would have to be tested individually to come up with an exact measure. The results in Table 1, however, are believed to reflect the range of radiation increases.

The government, however, does not require phone manufacturers to consider the effect of cases when they conduct compliance tests to meet the FCC’s allowable radiation exposure limits. The significance of this omission was underscored by tests commissioned by case-maker Pong Research and submitted to the FCC in May 2012. Those tests showed that three models of cases made by competing companies and used with an iPhone4 increased the phones’ Specific Absorption Rate, or SAR – the amount of radiation absorbed by the user’s body – by 20-to-70 percent (Table 1).

I also searched around to see if cell phone radiation was anything to worry about anyway. I turned up enough information from a lot of different credible sources to convince me it was worth protecting against the possible damaging effects of this radiation. IF there is no real health impact, then having a protective device would be overkill, but I figured better overkill than discover in time people started developing problems as a result of heavy cell phone use.

In a February 2 statement, Jeffrey Shuren, director of the FDA’s Center for Devices and Radiological Health, wrote that despite the NTP study’s results, the combined evidence on RF exposure and human cancer—which by now amounts to hundreds of studies—has “given us confidence that the current safety limits for cell phone radiation remain acceptable for protecting the public health.” Chonock says that for him, evidence from the Ramazzini study does not alter that conclusion. “We continue to agree with the FDA statement,” he says.

Exposure to ionizing radiation, such as from x-rays, is known to increase the risk of cancer. However, although many studies have examined the potential health effects of non-ionizing radiation from radar, microwave ovens, cell phones, and other sources, there is currently no consistent evidence that non-ionizing radiation increases cancer risk in humans (2).