So, what types of RF are these cases intended to block? If they block the frequency being used by the phone than if the blocking is complete the phone won’t work. If it’s partial than, as noted by the FCC and related in the article, the phone may attempt to compensate for the weakened signal by increasing it’s signal strength, thereby emitting higher levels of radiation itself, and reducing battery life in the process.
Instead, we have to rely on “observational” data, tracking people’s real-world cellphone use and their disease incidence. Studies using observational data tend to be weaker, messier, and less clear-cut than experimental studies like RCTs. They can only tell us about associations between phenomena, not whether one thing caused another to happen. So that opens up a lot of the ambiguity we’re going to delve into next.
Pong’s research indicates that badly designed cell phone cases can partially block a phone’s antenna, making the device work harder to transmit signals. Due to gaps in the FCC’s cell phone regulations, a phone worn right next to the body and enclosed by a case that obstructs the antenna could expose the user to more radiation than the FCC’s legal limit.

The electromagnetic spectrum is broken up into two parts based on whether small doses of that radiation can cause harm: ionizing radiation and non-ionizing radiation. Ionizing radiation—UV, x-rays, and gamma rays—has enough energy in one photon (quantized minimum packet of light) to remove electrons from atoms or break apart chemical bonds. It is because of this potential for cancer-causing DNA damage that you wear a lead vest when you get x-rays at the dentist and you are advised to wear sunblock when you go out in the sun. One can’t avoid natural (radon, cosmic rays when you are up in an airplane) and man made (diagnostic x-rays) sources of ionizing radiation completely, but it is reasonable advice to minimize exposure when possible.
In fact, nobody can really explain how exactly cellphone radiation could cause cancer, says Christopher Labos, a cardiologist and biostatistician at McGill University. “You don’t necessarily have to understand how something works to prove that it’s dangerous, but it would certainly make the case more compelling,” says Labos, who wrote a detailed analysis for Science-Based Medicine about the recent government cellphone radiation study.
We began by getting a baseline of ambient RF in the room at the location of our testing. We then recorded a baseline of the cellphone RF while on an active call with no case. And finally, we measured the reduction in that baseline (still on the active call) using a variety of different cases and RF reducing products – all at the same set distance from the phone.
The FCC provides information about the specific absorption rate (SAR) of cell phones produced and marketed within the last 1 to 2 years. The SAR corresponds with the relative amount of radiofrequency radiation absorbed by the head of a cell phone user (47). Consumers can access this information using the phone’s FCC ID number, which is usually located on the case of the phone, and the FCC’s ID search form.
You’ll notice radiation is split into two categories here: ionizing and non-ionizing. The waves emitted from radios, cellphones and cellphone towers, Wi-Fi routers, and microwaves are referred to as “radio-frequency” radiation. That’s a type of “non-ionizing” radiation, since it doesn’t carry enough energy to “ionize” — or strip electrons from atoms and molecules. (Other sources of non-ionizing radiation, as you can see in our chart, include visible and infrared light.)
The energy of electromagnetic radiation is determined by its frequency; ionizing radiation is high frequency, and therefore high energy, whereas non-ionizing radiation is low frequency, and therefore low energy. The NCI fact sheet Electromagnetic Fields and Cancer lists sources of radiofrequency radiation. More information about ionizing radiation can be found on the Radiation page.
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