Changing technology and methods of use. Older studies evaluated radiofrequency radiation exposure from analog cell phones. Today, cell phones use digital technology, which operates at a different frequency and a lower power level than analog phones. Digital cell phones have been in use for more than two decades in the United States, and cellular technology continues to change (3). Texting and other applications, for example, are common uses of cell phones that do not require bringing the phone close to the head. Furthermore, the use of hands-free technology, such as wired and wireless headsets, is increasing and may reduce exposure by distancing the phone from the body (36, 37).
Searching PubMed for studies published in the past 10 years, we found 102 studies that ultimately resulted in 12 relevant systematic reviews. To limit bias in our assessment of the literature, we used a validated critical appraisal tool called AMSTAR to determine the quality of each review. Eight of the reviews were critically low quality, two were low quality, and two were moderate quality.

Peer review is a vital part of any scientific study; it brings several more lifetimes of expertise into the room to rigorously check a study for any weak points. Melnick calls the peer reviewers’ choice to change some conclusions an unusual move; “It’s quite uncommon that the peer review panel changes the final determination,” he says, noting if anything, he’s seen peer reviewers downgrade findings, not upgrade them. “Typically when NTP presents their findings, the peer review almost in all cases goes along with that.” In this case, the peer reviewers felt the data—when combined with their knowledge of the cancers and with the study design itself—was significant enough to upgrade several of the findings.
Since speaking with Samet, further details came out from a large study that beamed high levels of phone radiation at rats and mice. While there remain quirks in the findings, the latest evidence still doesn’t find a link between phone radiation and cancer. In response, the FDA said, “Taken together, all of this research ... [has] given us the confidence that the current safety limits for cell phone radiation remain acceptable for protecting the public health.”
First, you must have a proper meter. To check for magnetic field emissions, an AC Gaussmeter will work. Most AC gaussmeters will have an internal probe. Simply position the gaussmeter on the phone. Note carefully where the meter 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 magnetic shield, and repeat.

A large, long-term study has been comparing all of the people in Denmark who had a cell phone subscription between 1982 and 1995 (about 400,000 people) to those without a subscription to look for a possible increase in brain tumors. The most recent update of the study followed people through 2007. Cell phone use, even for more than 13 years, was not linked with an increased risk of brain tumors, salivary gland tumors, or cancer overall, nor was there a link with any brain tumor subtypes or with tumors in any location within the brain.
Radio base licensing procedures have been established in the majority of urban spaces regulated either at municipal/county, provincial/state or national level. Mobile telephone service providers are, in many regions, required to obtain construction licenses, provide certification of antenna emission levels and assure compliance to ICNIRP standards and/or to other environmental legislation.

The researchers found other strange effects that muddied the interpretation of the studies: The rats exposed to cellphones seemed to outlive the rats in the control group, for example. There was no clear linear relationship between higher levels of cellphone exposure and more cancer at some tissue sites, and the cancer rate in the control group was lower than it should have been at other tissue sites.
They determined there is “clear evidence” that male rats exposed to high levels of radio frequency radiation — typical of 2G and 3G networks when the study was designed — developed heart schwannomas. There was also “some evidence” of brain and adrenal gland tumors, again in the male rats, but the exposed female rats, and male and female mice, did not have consistent patterns of disease.
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.

When we think of harmful radiation, things like X-rays or gamma rays usually come to mind, but these types of radiation are different from mobile phone radiation in important ways. Radiation on the ultraviolet side of visible light, like those types just mentioned, has a wavelength that is short enough to alter some of the chemical properties of the objects it interacts with. It is referred to as ionizing radiation, for this reason. Non-ionizing radiation, which includes visible light, microwaves and radio waves, is typically regarded as harmless. Large amounts of it can produce a heating effect, like in a microwave oven, but no short-term damage has been linked to exposure to non-ionizing radiation.

Stick on anti-radiation protection shields etc are often made of metal which may block signal and prevent reliable mobile phone communications with signal towers. Mobile phones recognise the potential for a dropped signal and actually increase power to compensate. The result is a fast draining battery and an even higher radiation output as a result of using the product (an exception to this are shields that are placed in between the phone and the user as these do not impede signal to cell towers to any significant degree)
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 Stewart report recommended that children should only use mobile phones in emergencies. The recommendation was based on the theory that children could be more at risk from the radiowaves emitted by mobile phones. This is because their brains are still developing and their skulls are thinner, making it easier for the radiowaves to penetrate them. Also if they start using mobiles at a young age, their cumulative lifetime use will be higher than adults. According to the Advisory Group on Non-Ionising Radiation, “little has been published specifically on childhood exposures” since 2000. As a result, children are still advised only to use mobile phones in emergencies. However, surveys suggest that many children are ignoring the advice. A survey of 1,000 British children, carried out in 2001, found 90% of under-16s own a mobile and one in 10 spends more than 45 minutes a day using it.
Users were defined as anyone who made at least one phone call per week for six months between 1982 and 1995. So any person who made 26 calls was a cell phone user and therefore considered exposed to radiation. Those with less than 26 calls were non-users. In reality, the radiation exposure between users and non-users defined in this manner is not discernable.
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.
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 outside is made of a synthetic polyurethane that feels just like leather, although genuine leather will be available soon. The inside is made of a microfiber that won’t scratch the phone. The materials are also designed to protect your phone, should you drop it. Most importantly, an integrated FCC-certified lab tested radiation-shielding foil not only deflects and absorbs RF, ELF and Thermal radiation to greatly reduce your exposure, but it also blocks RFID signals, so that hackers cannot steal your credit card information by scanning it from afar. And no, the case will not affect phone or battery performance.
“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.”
This substantially changes the debate on whether cell phone use is a cancer risk. Up until this point, the federal government and cell phone manufacturers operated on the assumption that cell phones cannot by their very nature cause cancer, because they emit non-ionizing radiation. Whereas ionizing radiation—the kind associated with x-rays, CT scans, and nuclear power plants, among others—definitely causes cancer at high enough doses, non-ionizing radiation was believed to not emit enough energy to break chemical bonds. That meant it couldn’t damage DNA, and therefore couldn’t lead to mutations that cause cancer.
With the background levels of information-carrying radio waves dramatically increasing because of the widespread use of cell phones,Wi-Fi, and other wireless communication, the effects from the near and far-fields are very similar. Overall, says Dr. Carlo, almost all of the acute and chronic symptoms seen in electrosensitive patients can be explained in some part by disrupted intercellular communication. These symptoms of electrosensitivity include inability to sleep, general malaise, and headaches. Could this explain the increase in recent years of conditions such as attention-deficit hyperactivity disorder (ADHD), autism, and anxiety disorder?
When you need to get further from your headset, this extension does the trick. Three feet long, white, and very light weight. Has standard iPhone 3.5 mm, 3 band plug and socket. Simply plug one end into your iPhone, and plug your headset into the other end. You can daisy chain up to 4 extensions to get a total length of 12 feet if you need it! Available in black or white.
EWG also reviewed data in the FCC filings on tests of battery life during a continuous call, measured on an iPhone 4 without a case and on the same phone with an Incipio Le Deux case. This case was chosen because it contains metallic parts (a stainless steel back plate). The presence of metallic components influences the phone’s radiation properties, as the FCC acknowledges (FCC 2001; FCC 2014). Under the test conditions with constant signal strength, an iPhone 4 without a case had 85 percent of battery capacity after a one-hour call and 70 percent after two hours. When the test was repeated with the Incipio Le Deux case, the phone had only 65 percent of battery capacity after a one-hour call and only 10 percent after two hours (Pong 2012).

RadiArmor’s anti-radiation material blocks over 99% of EMF radiation. However, since covering your entire phone with this material would result in no reception, only the front cover is lined with this material. This still provides an effective EMF reduction of 91% with no loss in reception. The front cover has a hole for sound to pass through so that you can close the case and talk at the same time. 

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.
to find the minimum distance the federal government recommends that your cell phone must be away from your body. Keeping it closer than the designated distance can result in a violation of the FCC Exposure Limit. Exceeding FCC levels is proven to result in burns, sterility and brain damage. Learn more about fine print instructions and see all the FCC warnings here.

To be fair I haven’t tried every single one on the list, but that just be careful in investing your sense of security, let alone good health, in a misplaced sense of something working just because someone says it does and they have “studies” to prove it. Every single company now claims “independently scientific studies” where as this is just usually falsified information and a marketing tactic.
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 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.
The CERENAT study, another case–control study conducted in multiple areas in France from 2004 to 2006 using data collected in face-to-face interviews using standardized questionnaires (18). This study found no association for either gliomas or meningiomas when comparing regular cell phone users with non-users. However, the heaviest users had significantly increased risks of both gliomas and meningiomas.