The exact source of radiation in a cell phone is from the transmitter, a device located near the antenna that converts audio data into electromagnetic waves. The amount of radiation a cell phone can emit is limited by legal restrictions in the U.S., Canada and Europe. Additionally, the average radiation levels of most mobile phones are available to the public, courtesy of the Federal Communications Commission in the U.S.
This is why it’s important to always use either your phone’s speakerphone or an appropriate wired earpiece whenever possible, avoiding direct contact between your phone and your ear or hand. The best earpieces are those equipped with hollow tubing between the antenna in the wire and the earpiece, as these help maximize the distance between the radiation-emitting antenna and your head.
The reason we’re talking about cellphones and cancer — why there’s a concern here — is because they emit radiation, the invisible waves of electric and magnetic energy, of varying power, organized on the electromagnetic spectrum. You can see in the graphic below that less powerful (or lower-frequency) types of radiation are on the left, moving to the more powerful (or higher-frequency) types of radiation on the right.
The dangers of driving and texting are old news; if someone were to be harmed by their cellphone’s radiation, though, that would make headlines because novelty grabs people’s attention. In psychological experiments where people have to choose images, they gravitate towards ones they haven’t seen before — a phenomenon known as the novelty bonus. So if I wanted to grab a reader’s attention, I’d bet on a hypothetical headline that said “For the first time, cellphone radiation causes brain cancer in humans” over “Another person has died today from driving and texting.”
Using the gauss meter at varied locations, you can easily detect electromagnetic radiation “hot spots” where exposure to these ominous frequencies is the greatest. Armed with this crucial information, you can then avoid these areas, re-arranging furniture or electronic devices as needed in order to avoid unnecessary exposure to electromagnetic radiation.

The International Agency for Research on Cancer (IARC) is part of the World Health Organization (WHO). Its major goal is to identify causes of cancer. The IARC has classified RF fields as “possibly carcinogenic to humans,” based on limited evidence of a possible increase in risk for brain tumors among cell phone users, and inadequate evidence for other types of cancer. (For more information on the IARC classification system, see Known and Probable Human Carcinogens.)
The only sure way is to stop using a cell phone. Most people however would prefer to play safe by simply reducing their exposure to radio frequency radiation. Bluetooth devices emit only 10% of the radiation of a cell phone. A hands-free set enables the user to keep the phone away from the head but usually leaves the phone near some other part of the body. It is safe to say that in the event that radio frequency radiation causes damage, you would like to protect other parts of your body. Therefore the only way to reduce your risk is to reduce the radio frequency radiation your body absorbs. SAR Shield reduces radio frequency radiation by up to 89%. 
To answer this question, Lloyd uses an analogy of “smoke and a chimney” to explain how a Pong case works.  It is unfortunate — given Lloyd’s personal experience with electrohypersensitivity and his straightforward knowledge of how to measure RF exposure — that pure “smoke and mirrors” clouded his better judgement when reviewing the Pong case for cell phone radiation safety.
“When symptoms are not addressed comprehensively– for example, using symptom amelioration without simultaneous elimination of exposure – cell membrane adverse reaction and damage continue to occur while the patient is assuming the cause of the problem has been eliminated. This lulls patients into a false sense of security, causing them to aggravate their exposures through the increased use of their wireless devices. When the damage reaches a critically harmful level, even the symptom amelioration can no longer be sustained by the damaged cells.”
But there is also some ambiguity about cellphone radiation’s health effects. As Dr. John Bucher, a senior scientist at the National Institute of Environmental Health Sciences and a co-author of the NIH studies, told me, “[Our results] go against the notion that non-ionizing radiation is completely harmless.” In other words, he’s found that the type of radiation cellphones give off could cause biological changes, like promoting tumors, at least in animals.

Yes, cell phones emit Electromagnetic Fields (EMF) and direct exposure to these emissions can be a health risk. There are two types of EMF radiation emitted from cell phones: Extremely Low Frequency (ELF) radiation and Radio Frequency (RF) radiation (which includes cellular signals, WiFi and Bluetooth). More and more, particularly in recent years, scientific studies have confirmed that these EMF exposure can adversely modify the biological operations of the body. In more serious cases, exposure to EMFs can lead to tumors, reduce sperm count and other serious health concerns.

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.
An analysis of data from NCI's Surveillance, Epidemiology, and End Results (SEER) Program evaluated trends in cancer incidence in the United States. This analysis found no increase in the incidence of brain or other central nervous system cancers between 1992 and 2006, despite the dramatic increase in cell phone use in this country during that time (22).