Changing technology and methods of use. Older studies evaluated radiofrequency radiation exposure from analog cell phones. Today, cell phones use digital technology, which operates at a different frequency and a lower power level than analog phones. Digital cell phones have been in use for more than two decades in the United States, and cellular technology continues to change (3). Texting and other applications, for example, are common uses of cell phones that do not require bringing the phone close to the head. Furthermore, the use of hands-free technology, such as wired and wireless headsets, is increasing and may reduce exposure by distancing the phone from the body (36, 37).

A decline in male sperm quality has been observed over several decades.[11][12][13] Studies on the impact of mobile radiation on male fertility are conflicting, and the effects of the radiofrequency electromagnetic radiation (RF-EMR) emitted by these devices on the reproductive systems are currently under active debate.[14][15][16][17] A 2012 review concluded that "together, the results of these studies have shown that RF-EMR decreases sperm count and motility and increases oxidative stress".[18][19] A 2017 study of 153 men that attended an academic fertility clinic in Boston, Massachusetts found that self-reported mobile phone use was not related to semen quality, and that carrying a mobile phone in the pants pocket was not related to semen quality.[20]
Stick on anti-radiation protection shields etc are often made of metal which may block signal and prevent reliable mobile phone communications with signal towers. Mobile phones recognise the potential for a dropped signal and actually increase power to compensate. The result is a fast draining battery and an even higher radiation output as a result of using the product (an exception to this are shields that are placed in between the phone and the user as these do not impede signal to cell towers to any significant degree)
Exposure to ionizing radiation, such as from x-rays, is known to increase the risk of cancer. However, although many studies have examined the potential health effects of non-ionizing radiation from radar, microwave ovens, cell phones, and other sources, there is currently no consistent evidence that non-ionizing radiation increases cancer risk in humans (2).