But researchers can make some judgments about the potential for harm based on how WiFi and similar technologies work, as well as on how people tend to use their devices. Those factors do provide some reasons to think that WiFi and Bluetooth devices may be less of a concern, says Leeka Kheifets, Ph.D., a professor of epidemiology at the UCLA School of Public Health who has studied the potential health effects of low-level radiation.
Results Renal tissue malondialdehyde (MDA) and total oxidant (TOS) levels of pre-natal group were high and total antioxidant (TAS) and superoxide dismutase (SOD) levels were low. Spot urine NAG/creatinine ratio was significantly higher in pre- and post-natal groups (p < 0.001). Tubular injury was detected in most of the specimens in post-natal groups. Immunohistochemical analysis showed low-intensity staining with Bax in cortex, high-intensity staining with Bcl-2 in cortical and medullar areas of pre-natal group (p values, 0.000, 0.002, 0.000, respectively) when compared with sham group. Bcl2/Bax staining intensity ratios of medullar and cortical area was higher in pre-natal group than sham group (p = 0.018, p = 0.011).
46. Tape your home number on your phone (or a parent’s cell phone number). “Imagine your child’s phone (or your own) is lost. Even if the person who finds it wants to return it, they have to go through your private information to find a number to dial. Make it easy. Tape your home number (or whatever number is suitable) to the back of the phone, along with information about a reward, if you like. That way, even with a password locking the keypad or screen, a do-gooder can get you your phone back!” – marianmerritt, Cell Phone Safety Tips for Kids, Norton Community by Symantec; Twitter: @NortonSupport
Numerous peer-reviewed studies have shown an association between cell phone use and the development of brain tumors. According to a Mar. 2008 meta-analysis of cell phone studies there is a "consistent pattern" connecting cell phone use and an increased risk of developing glioma, a type of brain tumor.  A Mar. 31, 2009 study found that long term cell phone use (10 years +) "approximately doubles the risk" of being diagnosed with glioma on the same side of the head where the cell phone is held.  In Apr. 2013 another study of Swedish cell phone users also found an association between cell phone use and the development of glioma and acoustic neuroma - a benign tumor formation on the nerve near the ear.  That study’s conclusions were confirmed by a different study in Apr. 2014.  Other studies published from 2005-2013 have similarly concluded that there is an association between cell phone use and increased risk of developing brain and head tumors.    
In a separate study by the same Swedish team, they found more than seven times the risk among people using a cell phone more than 20 years and 6.5 times the risk for long-term users of cordless phones. As expected, most of the gliomas and acoustic neuromas were on the same side of the head, which was usually exposed to the phone. In the 2013 official report on the medical evidence for brain tumors, the International Agency for Research on Cancer concluded that radiation from cell phones is “possibly carcinogenic to humans”.