The FCC provides information about the specific absorption rate (SAR) of cell phones produced and marketed within the last 1 to 2 years. The SAR corresponds with the relative amount of radiofrequency radiation absorbed by the head of a cell phone user (47). Consumers can access this information using the phone’s FCC ID number, which is usually located on the case of the phone, and the FCC’s ID search form.
The Working Group indicated that, although the human studies were susceptible to bias, the findings could not be dismissed as reflecting bias alone, and that a causal interpretation could not be excluded. The Working Group noted that any interpretation of the evidence should also consider that the observed associations could reflect chance, bias, or confounding rather than an underlying causal effect. In addition, the Working Group stated that the investigation of risk of cancer of the brain associated with cell phone use poses complex methodologic challenges in the conduct of the research and in the analysis and interpretation of findings.
If you want to use your phone for talking, then the idea is that you keep it flipped over the front of the screen – that way you’re blocking radiation on both the front and back. The speaker still works with the cover on, because there’s a small hole for that. The inevitable drawback of this is that you have to flip the cover open in order to access your keypad.
All cell phones emit Electromagnetic Radiation (EMR). Most people are aware of Radio Frequency (RF) (also known as Microwave) signals that connect your cell phone to a cell tower, a WiFi router and Bluetooth devices. These cell phone signals are always on. But did you know that cell phones also emit Extremely Low Frequency (ELF) radiation produced by the cell phone’s internal components?

But there is also some ambiguity about cellphone radiation’s health effects. As Dr. John Bucher, a senior scientist at the National Institute of Environmental Health Sciences and a co-author of the NIH studies, told me, “[Our results] go against the notion that non-ionizing radiation is completely harmless.” In other words, he’s found that the type of radiation cellphones give off could cause biological changes, like promoting tumors, at least in animals.

We did not simply measure energy coming from the front of the case which is the area of the case where the phone would be "shielded" from radiation. If we had taken readings with a directional meter, specifically measuring energy coming from only the front or flap cover where the shielding material is, we assume as the manufacturers claim, that we would have seen a drop in the radiation readings.
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The authors found a consistent effect, in both types of studies, that cellphone radiation leads to decreased sperm motility (ability to swim) and viability, but not a decrease in overall concentration. While it’s unclear if these specific changes are enough to affect men’s fertility, the authors wrote, “mobile phone exposure may form part of a cumulative effect of modern day environmental exposures, that collectively reduce sperm quality and explain current trends in infertility.”
Instead of more animal and even epidemiological studies, he thinks researchers should focus on finding the mechanisms by which cellphone radiation may affect human health. Since we’ll never have an RCT on cellphones and cancer, he added, studies should measure actual cellphone use and exposure to radio-frequency radiation, instead of estimations of how much people are exposed (which most studies currently do).
California officials issued the new report in response to increasing smartphone use in the United States, especially among children. About 95% of Americans own a cell phone, according to a press release from the California Department of Public Health, and the average age for a first cell phone is now 10 years old. About 12% of people use their smartphones for daily Internet access.

That’s why randomized controlled trials (RCTs) often yield fairly clear answers about the effectiveness of treatments compared to other study designs. (Fun fact: Scottish doctor James Lind, a clinical trial pioneer, figured out that citrus fruits seemed to have an effect on scurvy using one of the earliest RCTs.) RCTs can also be used to study whether something, like cellphone radiation, can cause disease.
SafeSleeve Anti Radiation Case: Safe Sleeve website says they integrate FCC accredited independent lab tested "shielding technology" in their products. There are many links to "SafeSleeve, Is it a Scam?" and "Does SafeSleeve work?" online, but if you follow those links you'll find they go to the actual SafeSleeve site where the question of SafeSleeve protection is addressed.  You'll see in this demonstration that the radiation level was higher with the SafeSleeve Case on.

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.