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.

Cables can act as an antenna, especially if they pass close to a strong source of radiofrequency radiation. One study has suggested that if the cable of a hands free mic passes near the phone's antenna, it can pick up some radiation and transmit it to your ear. Our ferrite snap bead is designed to reduce RF radiation in the cable. Made in 2 halves, you simply press it around the hands free wire at any convenient location near the earpiece end. Couldn't be simpler. It is small and lightweight enough to be almost unnoticable, yet powerful enough (50 ohm impedence minimum) to control nasty radiation. These are brand new, top quality and will accommodate wires up to 5 mm (3/16 inch) in diameter. About 1 inch long, grey color. If you are concerned about radiation from your hands free ear mic, this is the answer. Useful from 200-1000 MHz.
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.

INTEGRITY: Many manufactures claim near 100% EMF protection, referring to the radiation blocking material, NOT the protection you receive on a call. If you covered your whole phone with EMF blocking material, then you'd have no signal. Our EMF blocking material is used on the front cover only, providing you real EMF protection with no sacrifice in reception.
Also noteworthy is that the studies evaluated radiation exposures in different ways. The NTP looked at “near-field” exposures, which approximate how people are dosed while using cell phones. Ramazzini researchers looked at “far-field” exposures, which approximate the wireless RF radiation that bombards us from sources all around us, including wireless devices such as tablet and laptop computers. Yet they generated comparable results: Male rats in both studies (but not mice or female animals) developed schwannomas of the heart at statistically higher rates than control animals that were not exposed.
“I think the overall evidence that wireless radiation might cause adverse health effects is now strong enough that it’s almost unjustifiable for government agencies and scientists not to be alerting the public to the potential hazards,” says David O. Carpenter, M.D., director of the Institute for Health and the Environment at the University at Albany in New York and one of the authors of the recent letter to the U.N. and WHO.
So you are careful about NOT putting your radiation emitting mobile near your head. That’s good. But think about this: what body parts get the radiation when you put the thing on your pocket, bra, hat, purse, holster or elsewhere on your body? Now your vital and sometimes private organs are basically in contact with the source of the microwaves, getting the largest dose possible. Pocket Sticker is a high performance shielding patch that you stick onto your clothing which reflects that radiation away from your body.
Though some findings were reassuring, others do raise concerns. Specifically, three of the studies—one from Sweden, another from France, and a third that combined data from 13 countries—suggest a connection between heavy cell-phone use and gliomas, tumors that are usually cancerous and often deadly. One of those studies also hinted at a link between cell phones and acoustic neuromas (noncancerous tumors), and two studies hinted at meningiomas, a relatively common but usually not deadly brain tumor.

These expert committees determined that there are indeed gaps in the knowledge concerning the implications of exposure to this radiation, and therefore they called for further studies on the subjects and recommended to adopt the “precautionary principle". This principle adopts simple and relatively cheap means to reduce exposure to the minimum radiation levels possible with existing technology.
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.