The following charts list SAR levels for the Apple iPhone, Samsung Galaxy S, as well as 20 of the highest SAR level cellphones and 20 of the lowest SAR level cellphones. The list provides the maximum possible SAR level from the phone (many phones have differing SAR levels depending on where and how the phone is used). If your phone is not on either list, you can find the SAR level for your specific phone by checking the online FCC database.
We couldn't find one legit EMF expert online or anywhere else that would recommend a radiation blocking case or anti-radiation case. Not the Environmental Health Trust or Magda Havas, or Joel Moskowitz, in fact his site, safeEMR cautions against scams and claims for radiation protection.  So if a so-called "EMF expert" is recommending any kind of anti-radiation case, they probably aren't that much of an expert. 
Scientists have reported adverse health effects of using mobile phones including changes in brain activity, reaction times, and sleep patterns. More studies are underway to try to confirm these findings. When mobile phones are used very close to some medical devices (including pacemakers, implantable defibrillators, and certain hearing aids) there is the possibility of causing interference with their operation. There is also the potential of interference between mobile phones signals and aircraft electronics. Some countries have licensed mobile phone use on aircraft during flight using systems that control the phone output power.

In June, at a meeting of scientific counselors to the toxicology agency, Donald Stump, one of the members, worried that the study “will be vulnerable to criticism that it was conducted using outdated technology.” The challenge, he added, is how to move forward with experiments that are large enough to be significant yet nimble enough to keep pace with the rapidly evolving devices.

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 exact source of radiation in a cell phone is from the transmitter, a device located near the antenna that converts audio data into electromagnetic waves. The amount of radiation a cell phone can emit is limited by legal restrictions in the U.S., Canada and Europe. Additionally, the average radiation levels of most mobile phones are available to the public, courtesy of the Federal Communications Commission in the U.S.
We purchased a cell phone case directly from SafeSleeve. Once received, we attempted to determine how much radiation protection is actually possible from the product. What we learned is that NONE of the products SafeSleeve sells are actually tested by an FCC approved lab. Their advertising is very misleading! The testing results they use as "proof" that their products are tested was a single test done ONLY on a piece of material they claim is used inside their products. NONE OF THEIR PRODUCTS HAVE EVER BEEN TESTED BY AN FCC APPROVED TESTING LAB. We read the test report from SafeSleeve's website and called the testing lab listed on the report who verified this information. We also called an independent, FCC approved cell phone testing lab and they explained the same thing. We were informed that radiation comes from all sides and edges of a cell phone, so when you use the SafeSleeve cell phone case, you are NOT being protected. SafeSleeve cell phone cases offer you no more protection than using a cell phone without a case. To protect yourself from cell phone radiation, you still need to use hold the phone at least 6-8 inches from your body, use the speaker for conversations, text more than talk, and don't use or carry your cell phone against your body. We attempted to have the SafeSleeve cell phone case tested and were informed that to have it properly tested would require paying thousands of dollars in a lab equipped for such testing; using an RF meter or similar device to test a cell phone case will not provide meaningful or accurate results. If SafeSleeve were an honest company, they would have each of their products tested in an FCC approved lab, the same type of lab that cell phones are tested in. However, SafeSleeve is not willing to spend the money. If you don't believe us, call an FCC approved cell phone testing lab and ask a few questions. In the meantime, don't waste your money on SafeSleeve products. Note: SafeSleeve attempts to protect themselves by not listing any business phone number or business address on their website. Any questions/complaints you may have with SafeSleeve are strictly handled via email. They refused our request to speak to a "real person" regarding our questions or issues with their products. Does the word SCAM apply here? We think so.
In the studies, the researchers looked at a whole slew of health outcomes (like offspring survival, bodyweight changes, and body temperature changes), but importantly, they also looked at brain tumors, including gliomas. They exposed the animals to radio frequency radiation for up to nine hours a day over two years, and then examined more than 40 tissues in each animal. And they had a control group that wasn’t exposed to radiation for comparison.
Mobile devices work by sending radio waves in the air. And while the National Cancer Institute has pointed out that the radio-frequency (RF) energy cell phone emits is low, it does not discount the possible long term health risks it poses. Some of the most recent smartphones (such as the iPhone 7 in particular), release a higher level of radiation than older cellphones; and with people spending more and more time on their devices, it’s only a matter of time before adverse effects might catch up.

Then there is non-ionizing radiation, which encompasses the vast majority of light we are exposed to: visible light from lightbulbs, infrared light from an oven and from people, gigahertz light from our wifi, megahertz light to/from our cell phones, and radio waves hitting our car radio. They are not harmful in small doses because one photon does not have enough energy to ionize atoms and/or break apart molecules. In very large doses, non-ionizing radiation can be harmful. For example, a visible light laser with sufficient power (at least several hundred times more than a legal laser pointer) which is concentrated in a small enough spot will burn your skin and do worse things to your eye if it gets in there. And those of us who are old enough, remember the gerbil-in-a-microwave flash animations which went viral 17 years ago [1] as a humorous (but not exactly factual) representation of what would happen if you microwaved a live rodent.
*SAR values are from tests conducted by Pong Research Corp on March 29, 2012 and submitted to the FCC on May 31, 2012. Because the SAR values were submitted to the FCC in graph form, EWG estimated numerical SAR values based on the chart available in WT Docket 11-186 ( Pong’s filing to the FCC did not indicate whether SAR measurements were done at the head or in a body-worn configuration. In a personal communication, Pong informed EWG that the SAR measurements were done in a body-worn configuration, with the same distance from the test mannequin used by the phone manufacturer. Tests in the body-worn configuration were done at a 10 millimeter separation distance.
Researchers have carried out several types of epidemiologic studies in humans to investigate the possibility of a relationship between cell phone use and the risk of malignant (cancerous) brain tumors, such as gliomas, as well as benign (noncancerous) tumors, such as acoustic neuroma (tumors in the cells of the nerve responsible for hearing that are also known as vestibular schwannomas), meningiomas (usually benign tumors in the membranes that cover and protect the brain and spinal cord), and parotid gland tumors (tumors in the salivary glands) (3).