When it comes to ionizing radiation — which we’re exposed to in X-rays, in CT scans, and during air travel — we know it’s powerful enough to damage the DNA, and that repeated DNA damage over time can cause cancer. That’s why, for example, you’re not supposed to get too many X-rays in your lifetime. (In case you were wondering, there’s no precise number on how many X-rays are too many — but the Food and Drug Administration suggests keeping track and avoiding any that seem unnecessary.)
It’s easy to call any case a product designed to block smartphone radiation.  What you need to look for is credible, quantifiable claims that highlight a case’s ability to reduce your exposure to the harmful radiation. Look for relevant  certifications from credible organizations (such as FCC accredited laboratories) that will vouch for product claims, and read product reviews online.
The Pong Case is easy to use and snaps on to activate two built in antenna that draw away radiation. Tests performed by Pong labs and Wired magazine show that Pong cases redirect energy from the face of the cell phone or tablet toward the back of the device, reducing absorption by 67%. While one might think this would interrupt reception, the opposite occurs and reception has actually been observed to increase up to 13%. It fits most major phone brands and Pong also makes a case for the iPad (however it works a little differently and diffuses the energy instead of redirecting). The products come with a 6 month warranty and a 60 day money back guarantee. For more information, visit their website or watch these videos.
There are fears that the electromagnetic radiation emitted from mobile phone handsets may harm health. In particular, there have been claims that it could affect the body’s cells, brain or immune system and increase the risk of developing a range of diseases from cancer to Alzheimer’s. Laboratory tests on mice have shown that radiation from mobile phones can have an adverse effect on their overall health. It is still not clear whether those findings can be applied directly to humans. A study by scientists in Finland, published in 2002, suggested that the electromagnetic radiation did affect human brain tissue. But they played down their findings saying more research was needed to see if the effects were the same in living people. Another study by scientists in Sweden, also published in 2002, claimed to have found a link between analogue mobile phones and brain tumours. It suggested users of “first generation” phones had a 30% higher risk of developing tumours than people who did not. However, the findings were controversial and there have been no similar studies into the effects of modern GSM phones. There have also been reports of people suffering from headaches, fatigue and loss of concentration after using their mobile phones. However, these claims have not been scientifically substantiated.
A phone's specific absorption rate (SAR) reveals the maximum amount of radiation the human body absorbs from the phone while it's transmitting. SAR testing ensures that the devices sold in the U.S. comply with the Federal Communications Commission (FCC) SAR exposure limit, but the single, worst-case value obtained from this SAR testing is not necessarily representative of the absorption during actual use, and therefore it is not recommended for comparisons among phones. In short, selecting a lower SAR phone will not reliably ensure lower radiation absorption during use. The FCC has more information at Specific Absorption Rate (SAR) For Cell Phones: What It Means For You.
Four years ago -- before I bought my first iPhone -- I wouldn’t buy certain model cell phones because their radiation emission levels were too high. I became obsessed with researching this in the buying process, especially after finding out that a man I knew died of brain cancer and was an early mobile phone user. Suspicion was that the phone caused the cancer.
Rats were exposed to radiation with a frequency of 900 megahertz, typical of the cellphones in use when the study was conceived in the 90s, for about nine hours per day for two years, The New York Times reports. The lowest levels of radiation used in the study were equivalent to the maximum exposure a phone can cause and still receive federal regulatory approval; the highest levels to which the animals were exposed were four times that. 

The World Health Organization states that "A large number of studies have been performed over the last two decades to assess whether mobile phones pose a potential health risk. To date, no adverse health effects have been established as being caused by mobile phone use."[2] In a 2018 statement, the FDA said that "the current safety limits are set to include a 50-fold safety margin from observed effects of radiofrequency energy exposure".[3]

So, you've read the numerous studies about the potentially harmful health effects of cell phone radiation and you are ready to something about it. Of course, you can use your phone sparingly and put it in airplane mode when possible, use a wired headset or speakerphone when on calls, and never store it in your pocket. However, is that realistic? How about for your kids? In today's world, with our increasing dependence on our cell phones, probably not!
A carrier wave oscillates at 1900 megahertz (MHz) in most phones, which is mostly invisible to our biological tissue and doesn’t do damage. The information-carrying secondary wave necessary to interpret voice or data is the problem, says Dr. Carlo. That wave cycles in a hertz (Hz) range familiar to the body. Your heart, for example, beats at two cycles per second, or two Hz. Our bodies recognize the information-carrying wave as an “invader,” setting in place protective biochemical reactions that alter physiology and cause biological problems that include intracellular free-radical buildup, leakage in the blood-brain barrier, genetic damage, disruption of intercellular communication, and an increase in the risk of tumors. The health dangers of recognizing the signal, therefore, aren’t from direct damage, but rather are due to the biochemical responses in the cell.
What the study showed: Most published analyses from this study have shown no statistically significant increases in brain or central nervous system cancers related to higher amounts of cell phone use. One analysis showed a statistically significant, although modest, increase in the risk of glioma among the small proportion of study participants who spent the most total time on cell phone calls. However, the researchers considered this finding inconclusive because they felt that the amount of use reported by some respondents was unlikely and because the participants who reported lower levels of use appeared to have a slightly reduced risk of brain cancer compared with people who did not use cell phones regularly (4–6).