As Jonathan Samet — the dean of the Colorado School of Public Health, who advised the World Health Organization on cellphone radiation and cancer — told me, you can argue anything based on the science we currently have “because there’s not enough evidence to start with.” Actually, there’s not enough high-quality evidence. Before we get into why, and what we know, we need a quick primer on cellphone radiation.
Anti-radiation or radiation blocking or phone shield cases. Do they Work? SafeSleeve, DefenderShield, Vest, Alara, Pong, Reach and ShieldMe  and other EMF protection phone cases claim to block the radiation from your cellphone or smartphone. Anti-radiation cellphone case brands make enticing claims like this: ". . .eliminate up to 99% of the harmful radiation coming from the phone!"
The tricky part about measuring the radiation from a cell phone is that the emission strength varies widely over time. There will be strong bursts of varying intensity, followed by quiet periods. This makes it hard to compare "apples to apples". Also, because you are measuring up close to the source, you must use a near field meter AND you must maintain the position of the meter very precisely.
Stephen Chanock, who directs the Division of Cancer Epidemiology and Genetics at the National Cancer Institute, remains skeptical, however. Cancer monitoring by the institute and other organizations has yet to show increasing numbers of brain tumors in the general population, he says. Tracking of benign brain tumors, such as acoustic neuromas, was initiated in 2004 by investigators at the institute’s Surveillance, Epidemiology and End Results program, which monitors and publishes statistics on cancer incidence rates. According to Chanock’s spokesperson, the acoustic neuroma data “haven’t accumulated to the point that we can say something meaningful about them.”

SAR Shield was developed using the P.A.M. SYSTEM® technology. The materials used in the construction of the SAR Shield attract and dissipate electro-magnetic waves. As radiation travels it uses up its energy. What SAR Shield does is it acts like a radiation magnet, constantly attracting the radiation towards it, therefore making it release its energy closer to the phone. This causes most of the radiation to dissapate away from the head and body. SAR Shield does not cause noticeable reduction in signal strength.

Radiofrequency radiation is a form of electromagnetic radiation. Electromagnetic radiation can be categorized into two types: ionizing (e.g., x-rays, radon, and cosmic rays) and non-ionizing (e.g., radiofrequency and extremely low frequency, or power frequency). Electromagnetic radiation is defined according to its wavelength and frequency, which is the number of cycles of a wave that pass a reference point per second. Electromagnetic frequencies are described in units called hertz (Hz).