Some products ( for example) are tested using a piece of shielding material in a laboratory test jig. These tests legitimately show the amount of radiation which penetrates the shield, but results will be very different when compared to putting a small amount of the same shield on a large transmitter like a cellphone. Remember, the entire phone radiates. Placing a small amount of shielding, even if it is an effective shielding material, only shields that small area at best. Think about this analogy: no light will penetrate a penny as it is a very effective light shield, but it is silly to think that holding a penny up to the sun will put you in darkness.
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.

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.
Pong Research also makes cases for the iPad and its technology is arguably better suited for that. Why? Because serving as a stand to prop up your iPad or tablet, it means you don’t really need to hold it. That’s an ideal setup because higher amounts of radiation are going out the back, versus the front of the screen which you are touching with your fingers and palms.
The base station is equipped with antennas for reception and transmission. In order to communicate, the mobile phones and the antennas at the base station emit radiowave radiation (see below). The mobile phone instrument transmits a lower amount of radiation than the one transmitted by the transmission center (cell site), but because the instrument is near the body, the body directly absorbs the energy from the instrument’s antenna.
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.
Jump up ^ Repacholi MH, Lerchl A, Röösli M, Sienkiewicz Z, Auvinen A, Breckenkamp J, d'Inzeo G, Elliott P, Frei P, Heinrich S, Lagroye I, Lahkola A, McCormick DL, Thomas S, Vecchia P (2012). "Systematic review of wireless phone use and brain cancer and other head tumors". Bioelectromagnetics (Systematic review). 33 (3): 187–206. doi:10.1002/bem.20716. PMID 22021071.
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.
These cases work by redirecting the electromagnetic radiation (EMR) that is produced by phones, away from the user. All phones produce EMR when connected to the mobile network, and the effect of this energy is measured as a Specific Absorption Rate, or SAR: a measurement describing the radiation absorbed by kilogram of tissue. Government regulations in Australia dictate that all phones in Australia must emit a SAR less than 2 W/kg under the worst case scenario, and while all phones comply, most modern phones emit, at most, only half of this safe level, or approximately 1 W/kg.

Use a corded home phone whenever possible, to minimize the need for a cell phone. Cordless home phones emit RF, so replace cordless phones with corded home phones. One initial step is to unplug the electrical cord of the cordless phone base station when the phone is not in use, because otherwise that base station will emit RF nonstop. Note: you can plug a corded phone handset or corded headset into your VoIP connection.  
The U.S. Food and Drug Administration (FDA) notes that studies reporting biological changes associated with radiofrequency radiation have failed to be replicated and that the majority of human epidemiologic studies have failed to show a relationship between exposure to radiofrequency radiation from cell phones and health problems. The FDA, which originally nominated this exposure for review by the NTP in 1999, issued a statement on the draft NTP reports released in February 2018, saying “based on this current information, we believe the current safety limits for cell phones are acceptable for protecting the public health.” FDA and the Federal Communications Commission share responsibility for regulating cell phone technologies.
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"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.
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.
The Ministry of Health Medical Administration circular (from 2002) addressed to hospital Directors, states that use of mobile phones and wireless handheld transceivers (walkie talkie) in the hospital, must on the one hand guarantee the patient’s wellbeing and safety, and on the other hand, allow the staff, the patients and their families to enjoy the service benefits. This circular outlines the areas where use of mobile phones is strictly forbidden and areas where use is permitted (while keeping an appropriate safety distance from areas where life-supporting equipment or systems are operated).

I love this case. However, I don't understand what happens to the radiation that must collect under the case; isn't there a burst of radiation when the case is opened? I posted this question but the answers were from people who hadn't thought of that issue; they didn't have the answer, except for one who theorized that the radiation is slowly leaking out the top, bottom, and sides. I assume the case keeps radiation off the hand that holds the case with the phone in it, which is great, but I do wonder about the stored radiation when, for example, I'm listening to a podcast with the case closed, then open it later.

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.