EWG is calling on the FCC to update its testing guidelines to take account of the widespread use of smartphone cases. Such action is critical because mounting scientific studies have raised serious questions about the safety of cell phone radiation exposure over the short and long term. In the absence of meaningful action by the Commission, EWG offers consumers tips on how to reduce their exposure to cell phone radiation.
The World Health Organisation (WHO) released a fact sheet about these issues, shortly after the IARC re-classification, entitled "Electromagnetic fields and public health: mobile phones". The fact sheet points to the findings of the IARC and describes some of the known short-term and long-term effects of phone use, but ultimately, it lands on the side of where the most conclusive evidence exists:

The three most common brain tumor types — and the ones most cellphone and human health studies focused on — are gliomas (malignant tumors of the brain and spinal cord), meningiomas (mostly noncancerous tumors of the membranes surrounding the brain and spinal cord, though a small percentage are cancerous), and acoustic neuromas (noncancerous tumors on the main nerve that leads from the inner ear to the brain). Note that of these, gliomas are the main concern — they generally have more severe outcomes than meningiomas and acoustic neuromas.

Since 2001, the FCC has allowed manufacturers to test phones at a distance of up to one inch from the body to account for the use of a holster. In a 2012 report, however, the Government Accountability Office, the Congressional watchdog agency, noted that many cell phone owners actually keep and use their phones right next to the body, so these outdated testing policies could result in radiofrequency (RF) radiation exposure greater than the FCC’s legal limit (GAO 2012). The GAO report concluded:
EWG urges the FCC to include third party-produced cases and accessories in its cell phone testing policies to ensure that they do not compromise cell phone function and do not prevent a cell phone from complying with the Commission’s exposure limits. Manufacturers should publish the radiation data for a given phone when used directly next to the body and when used with the cases most commonly sold for a specific model.

Epidemiology studies investigating cell phone use patterns with human cancer risk have produced inconsistent results. Some studies enrolled people who already had tumors with suspected links to RF radiation, such as gliomas, acoustic neuromas and salivary gland tumors. Researchers compared the self-reported cell phone use habits of the cancer patients with those of other people who did not have the same diseases. Other studies enrolled people while they were still healthy, and then followed them over time to see if new cancer diagnoses tracked with how they used cell phones. All the epidemiology studies, however, have troubling limitations, including that enrolled subjects often do not report their cell phone use habits accurately on questionnaires.

The main difference between our product and other radiation shields available on the internet is simple. OUR PRODUCT WORKS. We are the only cell phone radiation shield that provides full testing on our product by a leading SAR testing lab, IMST which tested the cell phones in the now famous ABC News 20/20 report, and publish these SAR Shield radiation tests on our website for everyone to scrutinize. In 2002 the US government tested various shields, and found that many did not work. The FTC then sued several makers of radiation blockers including, Wave Scrambler, Safety Cell and SafeTshield. This action was taken after Good Housekeeping Institute found that 5 shields did not reduce the radiation they claimed, these five shields were Wave Scrambler by Rhino International, Radiation Free Shield, Wave Shield by Interact Communications, Safe-T-Shield by SV1 Inc, and Safety Caps by Safety Cell. It is easy to say a product reduces radiation, but why don’t our “competitors” publish these results so we can actually see the claims they make are real?

As far as which of those match your device, that really depends on your carrier. AT&T, Verizon, Sprint, and T-Mobile all have different frequencies. To further complicate things, in one geographic region of the country they may use one frequency, while another is used elsewhere. It all depends on which FCC licenses they have the rights to in each region.
Studies in people: Another type of study looks at cancer rates in different groups of people. Such a study might compare the cancer rate in a group exposed to something like cell phone use to the rate in a group not exposed to it, or compare it to what the expected cancer rate would be in the general population. But sometimes it can be hard to know what the results of these studies mean, because many other factors that might affect the results are hard to account for.
Take a closer look at the product claims. Many refer to their “shielding technology” and not the product itself. In many cases, the “FCC Certified” labs they cite are actually testing how much RF the raw shielding material can block. They’re testing the materials used in the products. They’re not testing how much RF the actual products block while on a real-world phone.
Ideal for hands-free communication. Dramatically reduces microwave exposure by keeping the phone away from your head! Comfort-fit adjustable headband design. Reversible to use with either ear. Also features an adjustable boom microphone for optimum voice output and a four-foot cord. Can also be used with your tape or CD player, etc. Very comfortable, especially for long term wear. Better hold. Quicker to put on than ear bud style headsets. Add a ferrite bead for added protection.
The bulk of scientific evidence says that cellphone radiation doesn’t harm humans, according to the Food and Drug Administration: our cellphones are much more likely to kill us when we glance down at them while driving. But people are bad at judging risk. And the word “radiation” combined with the fact that we can’t see or control the invisible forces emanating from our cellphones becomes a perfect recipe for fear.
To check for radiowave emissions, use an RF meter with Near Field antenna. Again, position the antenna loop on the phone (because the entire antenna stem has some sensitivity, it is best to position the entire antenna over the area that will be shielded). Note carefully where the loop is positioned. Make a call and watch the readings. Notice the highest and lowest readings, and make a mental note of the "average" reading. Now, insert the shield, and repeat.
I have not gotten a cell phone, I was gifted a tablet, but it stays off most of the time, I use a desktop PC and my home phone is still landline but cordless. For me it’s been a bit of mixed bag in that I don’t want to rely so heavily on technology to do and remember things for me. When I hear about the new and latest tech that can now do X,Y, or Z for you, I think of the two little boys in the 80’s Cafe in BTTF.

The effect of mobile phone radiation on human health is a subject of interest and study worldwide, as a result of the enormous increase in mobile phone usage throughout the world. As of 2015, there were 7.4 billion subscriptions worldwide, though the actual number of users is lower as many users own more than one mobile phone.[1] Mobile phones use electromagnetic radiation in the microwave range (450–3800 MHz and 24-80GHz in 5G mobile). Other digital wireless systems, such as data communication networks, produce similar radiation.

"Possibly carcinogenic" was a phrase that may media outlets pulled out of the release, but it's a dangerous takeaway for consumers, out of context. "Possibly carcinogenic to humans", or group 2B, is a sub-classification or monograph, applied to agents by the IARC. Other agents (or items of everyday life) in Group 2B include pickled vegetables, lead and Potassium bromate — an oxidising additive common in flour. In all, there are 272 agents listed as possibly carcinogenic.
3. A lab setting is the only legitimate way to show the effectiveness of our technology for a few main reasons: one, a controlled source is the only way to conduct a scientific study. Note that the controlled source that we used was specifically designed to simulate emissions from wireless electronics (RF and ELF emissions of various frequencies). Two, ambient levels in a non-controlled environment will affect readings, rendering the results inaccurate. Three, at-home equipment such as the meter used in the video is not suitable for the types of emissions by a wireless device, nor are they reliable.

The amount of RF energy absorbed from the phone into the user’s body is known as the specific absorption rate (SAR). Different cell phones have different SAR levels. Cell phone makers are required to report the maximum SAR level of their product to the US Federal Communications Commission (FCC). This information can often be found on the manufacturer’s website or in the user manual for the phone. The upper limit of SAR allowed in the United States is 1.6 watts per kilogram (W/kg) of body weight.

If you paid an electrical engineer to shield something for you, depending on the application, they would either use MuMetal or this type of mesh shielding. It’s not some new technology, so there’s no question of whether it works, because it does. Regardless, it would still be nice for them to publish third-party independent testing to reassure people of this.
The only consistently recognized biological effect of radiofrequency radiation in humans is heating. The ability of microwave ovens to heat food is one example of this effect of radiofrequency radiation. Radiofrequency exposure from cell phone use does cause heating to the area of the body where a cell phone or other device is held (e.g., the ear and head). However, it is not sufficient to measurably increase body temperature. There are no other clearly established effects on the human body from radiofrequency radiation.