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 reduce 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.
You hit the nail on the head when you say that distance is key when it comes to EMF exposure. The solutions you sell will definitely help provide that separation. That said, our products are different in that they shield the user from EMF while allowing them to use the device as they normally would, without needing to hold their device by a rope or placing it in a faraday cage that eliminates signal altogether.
People who say cell phones are safe reference statements by the FCC and Food and Drug Administration (FDA) and point to peer-reviewed studies which conclude that cell phone use is not associated with an increased risk of brain tumors or the onset of other health problems. They contend there has been no increase in brain tumor rates despite hundreds of millions of people now using cell phones.
Ionizing radiation gets is name because it has enough energy to excite electrons and knock them out of their orbit, or ionize, them. Extensive exposure to this kind of radiation is highly detrimental to the your health, and even low but persistent exposure over time can significantly increase your risk of cancer as exposure can mutate your cells. Even when used for beneficial purposes (like using an x-ray machine to diagnose a patient), the exposure is carefully controlled by the use of lead vests, shielding material, and so on so that the patient and the operator of the machine are given as minimal exposure as necessary. If you’re worried about radiation, this is the radiation you should be worried about. (And even then you shouldn’t be that worried as the amount of radiation you’re exposed to during routine medical procedures is, over the course of your lifetime, less than the amount of radiation you’re exposed to over the same period on the aircraft flights you take for business and vacations.)
I have treated patients with cancer for over thirty years as a board-certified radiation oncologist and I am familiar with every carcinogenic agent known to man. I'll tell you with absolute certainty that radio waves cannot harm you (unless perhaps you were in the path of a multi-megawatt microwave beam, in which case they might cook you. But as far as I know, there is no likelihood that this danger even exists).
Our recommendation is to reduce your exposure from wireless sources. We advocate what’s referred to as the Precautionary Principle. Basically, this means that because there’s research, lots of it actually, saying the energy that powers our cellphones (RF radiation) could be causing health concerns like tumors and cancer. We ought to take care when using our cell phones and all devices that emit RF, using them mindfully.
35. Check your child’s cell phone records. “Review cell phone records for any unknown numbers and late night phone calls and texts.” While it may feel as though you’re snooping on your kids, reviewing their calling and texting records can help you identify warning signs such as strange calling patterns or unfamiliar numbers that could indicate that your child is communicating with someone they shouldn’t be such as a potential predator. – Help children use cell phones safely, NetSmartz Workshop; Twitter: @NetSmartz
Want an official word on the matter? The World Health Organization, which tends to err on the side of caution before outright dismissing something as toxic, carcinogenic, or otherwise harmful, is very clear that there is no health risk from radio-frequency communication devices. (Their briefing on the matter is actually a great read that highlights how low the risk is and how even people in Wi-Fi dense locations like schools and hospitals are exposed to radio-frequency radiation at thousands of times lower than international safety standards designed to protect individuals working in related industries).
This Nation investigation reveals that the wireless industry not only made the same moral choices that the tobacco and fossil-fuel industries did; it also borrowed from the same public-relations playbook those industries pioneered. The playbook’s key insight is that an industry doesn’t have to win the scientific argument about safety; it only has to keep the argument going. That amounts to a win for the industry, because the apparent lack of certainty helps to reassure customers, even as it fends off government regulations and lawsuits that might pinch profits.20
I really want to caution you to be careful of any "expert" or EMF blogger recommending anti-radiation filtering cases, stickers that attach to the phone or necklaces to "ward off" EMF. I get it, when I first realized 25 years ago that I was sensitive to electromagnetic energy and then later, when I understood that without a doubt, man made electromagnetic radiation has a biological effect on my body, I wanted an easy fix. I tried the shielding materials and cases and I just did not feel any better. Then I bought meters to see if the energy changed and I actually noticed what the California Department of Health now says and it's what the FTC and FCC post warnings about: "Some shielding materials can make exposures worse". So please, be careful and read on for what you can do to avoid electromagnetic radiation exposure.
Wi-Fi transmissions consist of sequences of RF burst signals or pulses ranging in duration depending on the amount of data being carried by a pulse(15). The proportion of time that Wi-Fi transmits RF signals is called the duty cycle. Joseph et al.(14) in measuring Wi-Fi in 176 different urban locations (outdoors, homes, offices) found a median duty cycle of 1.4% over all the measurements. Particularly in schools, Khalid et al.(10) in measuring Wi-Fi in six schools found a mean duty cycle from the access points of 4.8%. In our study duty cycle was measured separately for the 2.45 and 5 GHz transmissions when performing the stationary Wi-Fi measurements in the centre of the classroom. The median duty cycle for 23 schools that were measured in the current study was 6.3 and 2.4% for 2.45 and 5 GHz transmissions, respectively.
A few years ago, the science regarding links between cell phone radiation and various health ailments was a very emergent science. Even today, most scientists disagree about many of the findings. However, the fact that so many new studies are discovering effects that cell phone radiation can have on human biology, it makes sense to play it safe. If there are no negative health effects, then you're only out a few bucks. But if it turns out there really are serious health issues related to cell phone radiation, then by protecting yourself early, you can protect your health and potentially save your life by getting a cell phone anti-radiation shield.
Long-term exposure to Radio Frequency waves or microwave radiation has long been studied and shown to produce all sorts of adverse health effects. See my post on EMF Radiation Exposure Symptoms for a full list of common symptoms. Even the American Cancer Society, who in large part will not fully say that EMF radiation causes long-term harm, and instead errs on the side of not enough research, admits on their website, that:
According to a Mar. 2008 meta-analysis of cell phone studies there is a "consistent pattern" connecting cell phone use and an increased risk of developing glioma, a type of brain tumor.  A Mar. 31, 2009 study found that long term cell phone use (10 years +) "approximately doubles the risk" of being diagnosed with glioma on the same side of the head where the cell phone is held.  In Apr. 2013 another study of Swedish cell phone users also found an association between cell phone use and the development of glioma and acoustic neuroma - a benign tumor formation on the nerve near the ear.  That study’s conclusions were confirmed by a different study in Apr. 2014.  Other studies published from 2005-2013 have similarly concluded that there is an association between cell phone use and increased risk of developing brain and head tumors.    
We asked Dr. George Carlo his thoughts on EMF cases and shielding products, “most offer some protection, some of the time, to some people, because they can alter the immediate electromagnetic field environment around the person,” and immediately emphasizes the importance of “some,” which seems to tell us that it’s vastly unpredictable. “All waveforms in the environment are highly variable and they interact with other factors in the environment that make them even more variable.” This pretty much sums up that the artificial electromagnetic energy universe is vastly unpredictable.
"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.
1. Be careful what you share. “Use the same good sense about what you post from your phone as from a computer. Once they’re posted, text, photos, and video are tough to take back, can be copied and pasted elsewhere, and are up there pretty much forever. Think about the people in them (including you!). Reputations are at stake.” – Tips for Smart Cellphone Use, Connect Safely; Twitter: @ConnectSafely