A 2012 study by NCI researchers (25) compared observed glioma incidence rates in U.S. SEER data with rates simulated from the small risks reported in the Interphone study (6) and the greatly increased risk of brain cancer among cell phone users reported in the Swedish pooled analysis (19). The authors concluded that overall, the incidence rates of glioma in the United States did not increase over the study period. They noted that the US rates could be consistent with the small increased risk seen among the subset of heaviest users in the Interphone study. The observed incidence trends were inconsistent with the high risks reported in the Swedish pooled study. These findings suggest that the increased risks observed in the Swedish study are not reflected in U.S. incidence trends.

Says Dr. Carlo: “We also conducted four different epidemiological studies on groups of people who used cell phones, and we did clinical intervention studies. For example, studies of people with implanted cardiac pacemakers were instrumental in our making recommendations to prevent interference between cell phones and pacemakers. In all, we conducted more than fifty studies that were peer-reviewed and published in a number of medical and scientific journals.”
The phone is placed in various positions on the head and body, including held to both ears, and all measurements are taken and reported to the FCC when the manufacturer is seeking approval. However, it should be noted that only the very highest SAR values for each type of radiation are included in final consideration for compliance with the FCC’s guidelines.
Consumers should utilize an air tube headset as a safer alternative to wired headsets or in-ear Bluetooth headsets, use the speaker feature and keep phones away from your body unless there is RF radiation shielding between the wireless device and cell phone users body.  When carrying a phone on your body it’s highly recommended to use either an RF Safe flip cover radiation shielded phone case or pocket shield to deflect excessive radiation away.

Dr. Carlo, wrote a  Medical Alert ten years ago. He cautioned people with EMF sensitivity against relying upon widely-available EMR Protection Products to prevent the effects of EMF exposure. He noted that EMF sensitive individuals were reporting the opposite effect: people found their symptoms and/or sensitivity worsened. Specifically, severe “symptom relapses.” Dr. Carlo noted:

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.
That’s because cell phones emit electromagnetic fields (EMFs) or electromagnetic radiation, which has the potential to damage the cells in the body. In fact, the International Agency for Research on Cancer classifies EMFs from cell phones as possible carcinogens. EMFs can interfere with the body’s natural electrical system and disrupt sleep, immune system function, hormone production, and the healing process. Kevin Byrne, president of EMF Solutions, also points out the simultaneous increase in conditions such as chronic pain, depression, anxiety, chronic fatigue syndrome, and Alzheimer’s disease and the significant rise in EMF exposure.
RF waves from cell phones have also been shown to produce “stress” proteins in human cells, according to research from Martin Blank, Ph.D., a special lecturer in the department of physiology and cellular biophysics at Columbia University and another signer of the recent letter to the WHO and U.N. “These proteins are used for protection,” Blank says. “The cell is saying that RF is bad for me and it has to do something about it.”
“If you're looking for ways to limit your exposure to the electromagnetic emissions from your cell phone, know that, according to the FTC, there is no scientific proof that so-called shields significantly reduced exposure from these electromagnetic emissions. In fact, products that block only the earpiece—or another small portion of the phone—are totally ineffective because the entire phone emits electromagnetic waves. What's more, these shields may interfere with the phone's signal, cause it to draw even more power to communicate with the base station, and possibly emit more radiation.”
The guidelines created a measure of the rate that body tissue absorbs radiation during cell phone use called the specific absorption rate (SAR). The SAR for cell phone radiation was set at a maximum of 1.6 watts of energy absorbed per kilogram of body weight. The limit was set due to the thermal effects of cell phone radiation (all RF radiation can heat human body tissue at high enough levels) - it was not set to mitigate other biological effects cell phone radiation might have such as DNA damage or cancer.

Cordless Phones - Most homes have cordless phones. Many of these cordless phones operate within 2.4GHz 5.8 GHz. These phones are high in electromagnetic radiation particularly when they get over 2.4 GHz. At this level they are operating at the same frequency as a cell phone. We suggest using Safe Cell on your cordless phone as well as your cell phone. 
Some studies have found a possible link. For example, several studies published by the same research group in Sweden have reported an increased risk of tumors on the side of the head where the cell phone was held, particularly with 10 or more years of use. It is hard to know what to make of these findings because most studies by other researchers have not had the same results, and there is no overall increase in brain tumors in Sweden during the years that correspond to these reports.
The science is still out on whether the long-term use of cell phones—which emit electromagnetic radiation when they send and receive signals from towers or WiFi devices—can affect human health. But for people who want to reduce their exposure to this type of energy, the California Department of Public Health has published new guidelines on how to do just that.
DefenderShield Cellphone Radiation Case also claims independent testing and says in their website: That a "sophisticated layering of separate non-toxic, human safe materials processed for maximum radiation blocking efficiency. Each material has unique and targeted radiation-shielding characteristics designed to work in unison to eliminate all radiation emissions from 0 to 10 GHZ and Defender Shield technology refracts, conducts and finally absorbs all these potentially harmful emissions."  In this demonstration, the radiation level measured when DefendeShield case was on is still quite a bit above the level of exposure that I would recommend. I personally do not recommend-holding a phone with a shielding case to your head as the DefenderShield website shows a young woman doing as she demonstrates the product. 
"To expect relief from radiation exposure from one specific device, is nearly impossible. It’s crucial to weigh in the MANY environmental factors; such as, temperature, atmospheric pressure, other radio waves, emissions from other devices, energy shifts from others around you, and Schumann Resonance shifts. Therefore," he explains that “relying on alteration of the environment as a safety precaution is always a game of chance…and signals affect people differently,” which adds another variables in the game of chance.
This is a 2 pieces of plastic sandwiched together by glue. Don't believe me? Take it apart. This item works no better than the existing case on your phone. If you are that concerned with cellphone radiation, you should be equally concerned about the cheap plastic and toxic glue that this is comprised of. Also know the fact that they've stolen $25 from your wallet when you purchase this hokey product...Technology at it's finest.
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.
SafeSleeve is garbage. And the customer service is even worse. I bought one in October 2017 and by the end of January 2018 the sticky patch had worn off to completely no longer be able to hold my phone. I contacted the company, and they would not replace it even though they recognized it was due to “normal wear” because they only have a 60 day warranty. And offered only a one-time 25% off coupon. for a $45 case only to be guaranteed for 2 months is absurd to me! I asked to be contacted by a manager as they do not have a phone number listed anywhere, just email address and has been a week and no response. Totally ignored.
The study also found that about 5 to 7 percent of the male rats exposed to the highest level of radiation developed certain heart tumors, called malignant schwannomas, compared to none in the control group. Malignant schwannomas are similar to acoustic neuromas, benign tumors that can develop in people, in the nerve that connects the ear to the brain.
Today’s report, the final one, was about a decade in the making and is the last of several versions that have been released since preliminary results were presented in May 2016. It represents the consensus of NTP scientists and a group of external reviewers, according to the release. In the future, the NTP plans to conduct studies in smaller exposure chambers and to use biomarkers such as DNA damage to gauge cancer risk. These changes in the experimental setup should mean that future studies will take less time.

Our homemade demonstration of all the cases uses a working phone. Not the shielding material by itself, but the actual "shielding" SafeSleeve, Pong, Reach,  Vest, ShieldMe, and Defender Shield cases. First we get RF power density measurements from a phone that's on a call and then, in the same location, within minutes of the first reading, we place the same phone as it's engaged in a call into each case and we take additional reading with the meter.
Specifically, we looked for studies that measured rates of acoustic neuromas, gliomas, meningiomas, and thyroid cancers. We also narrowed our search to studies that looked at the effect of radio-frequency radiation originating from an actual cellphone, rather than experimental equipment. We did this because we wanted evidence that could apply to real life, not specific laboratory settings or hypothetical outcomes.

Radiofrequency radiation is a form of electromagnetic radiation. Electromagnetic radiation can be categorized into two types: ionizing (e.g., x-rays, radon, and cosmic rays) and non-ionizing (e.g., radiofrequency and extremely low frequency, or power frequency). Electromagnetic radiation is defined according to its wavelength and frequency, which is the number of cycles of a wave that pass a reference point per second. Electromagnetic frequencies are described in units called hertz (Hz).