The electromagnetic spectrum is broken up into two parts based on whether small doses of that radiation can cause harm: ionizing radiation and non-ionizing radiation. Ionizing radiation—UV, x-rays, and gamma rays—has enough energy in one photon (quantized minimum packet of light) to remove electrons from atoms or break apart chemical bonds. It is because of this potential for cancer-causing DNA damage that you wear a lead vest when you get x-rays at the dentist and you are advised to wear sunblock when you go out in the sun. One can’t avoid natural (radon, cosmic rays when you are up in an airplane) and man made (diagnostic x-rays) sources of ionizing radiation completely, but it is reasonable advice to minimize exposure when possible.
The FCC has yet to implement GAO’s recommendations to more closely reflect real-life use. For a narrow subset of smartphones – those sold with lanyards or straps – the FCC advises manufacturers to test phones at a distance of no more than 5 mm from the body (FCC 2014). Yet the FCC has done nothing to ensure more realistic testing of most other smartphones or to account for the widespread use of accessories such as cases, which many different manufacturers produce with both metallic and non-metallic components.
In subsequent analyses of Interphone data, investigators addressed issues of risk according to specific location of the tumor and estimated exposures. One analysis of data from seven of the countries in the Interphone study found no relationship between brain tumor location and regions of the brain that were exposed to the highest level of radiofrequency radiation from cell phones (9). However, another study, using data from five of the countries, reported suggestions of an increased risk of glioma and, to a lesser extent, of meningioma developing in areas of the brain experiencing the highest exposure (10).
The International Agency for Research on Cancer (IARC) is part of the World Health Organization (WHO). Its major goal is to identify causes of cancer. The IARC has classified RF fields as “possibly carcinogenic to humans,” based on limited evidence of a possible increase in risk for brain tumors among cell phone users, and inadequate evidence for other types of cancer. (For more information on the IARC classification system, see Known and Probable Human Carcinogens.)

I debated whether to give it 3 or 4 stars: on features, speed of delivery, and quality of construction, it definitely deserves 4 stars. If I can measure and verify the emf reduction, then I will change the rating to 5 stars. Since the whole point of using it is to block excess em radiation, I can't really give it 5 stars without more proof that it really does so.

There’s a broad range of radiation types, and lots of harmless things emit radiation — like bananas, Brazil nuts, and granite countertops, according to Cincinnati Children’s Hospital. The type of radiation that comes out of our cellphones isn’t the same radiation that’s released by nuclear fallout or X-rays. Cellphone radiation, also known as radiofrequency radiation, is much weaker — so it can’t cause the same kind of cell damage that can lead to cancer.
We used a few measuring devices to test and see if this product actually blocks radiation and RFID, including a very sophisticated EMF reader. I am glad to say that this is actually a very effective way to reduce radiation. It is most effective on the front side, and when you have it closed and latched, there is very little exposure - only along the top, side and bottom opening.
EWG also reviewed data in the FCC filings on tests of battery life during a continuous call, measured on an iPhone 4 without a case and on the same phone with an Incipio Le Deux case. This case was chosen because it contains metallic parts (a stainless steel back plate). The presence of metallic components influences the phone’s radiation properties, as the FCC acknowledges (FCC 2001; FCC 2014). Under the test conditions with constant signal strength, an iPhone 4 without a case had 85 percent of battery capacity after a one-hour call and 70 percent after two hours. When the test was repeated with the Incipio Le Deux case, the phone had only 65 percent of battery capacity after a one-hour call and only 10 percent after two hours (Pong 2012).
To be fair I haven’t tried every single one on the list, but that just be careful in investing your sense of security, let alone good health, in a misplaced sense of something working just because someone says it does and they have “studies” to prove it. Every single company now claims “independently scientific studies” where as this is just usually falsified information and a marketing tactic.
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.