According to American Academy of Pediatrics President Dr. Robert Block, when cell phones are used by children, "the average RF energy deposition is two times higher in the brain and 10 times higher in the bone marrow of the skull," than for adults.  A July 2008 peer-reviewed study shows that children under the age of eight absorb twice the amount of radiation into their brain tissue as adults due to their lower skull thickness. 
In the current study, the pattern of the response of E coli to Wi-Fi and RF simulator radiation was identical. The maximum differences in the diameters of inhibition zones were observed between 6 and 9 hours of the bacterial exposure to radiation (Figures 1 and 2). After 12 hours of exposure, the bacterial responses to radiation as a stressor led to returning to the preexposure status.
Lack of definitive proof that a technology is harmful does not mean the technology is safe, yet the wireless industry has succeeded in selling this logical fallacy to the world. In truth, the safety of wireless technology has been an unsettled question since the industry’s earliest days. The upshot is that, over the past 30 years, billions of people around the world have been subjected to a massive public-health experiment: Use a cell phone today, find out later if it causes cancer or genetic damage. Meanwhile, the wireless industry has obstructed a full and fair understanding of the current science, aided by government agencies that have prioritized commercial interests over human health and news organizations that have failed to inform the public about what the scientific community really thinks. In other words, this public-health experiment has been conducted without the informed consent of its subjects, even as the industry keeps its thumb on the scale.27
In 2011, the American Cancer Society (ACS) stated that the IARC classification means that there could be some cancer risk associated with radiofrequency radiation, but the evidence is not strong enough to be considered causal and needs to be investigated further. Individuals who are concerned about radiofrequency radiation exposure can limit their exposure, including using an ear piece and limiting cell phone use, particularly among children.
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.    
39. Beware of cyberbullying. Cyberbullying is yet another reason to monitor your child’s smartphone usage including call and text message records. While your child may not always tell you when they’re being mistreated by a friend or acquaintance, seeing threatening or bullying messages on your child’s phone will allow you to address issues before they escalate to dangerous levels. “Cyber bullies, adults and children alike, harass others by sending threatening or rude texts to cell phones.” – What Are Some Cell Phone Safety Tips For Kids?, How Stuff Works; Twitter: @HowStuffWorks
In certain situations, it's necessary to use your cell phone when your hands are otherwise occupied. For those times, a Bluetooth headset comes in handy. These lightweight headsets attach above one or both of your ears or around your neck, and allow you to talk without having to do so directly into your phone. These are rechargeable devices that offer around eight hours of talk time. You can also listen to music and use GPS applications and many other apps that your phone has. Bluetooth headsets are compatible with most or all Bluetooth-enabled mobile devices.
People who say cell phones are not safe cite peer-reviewed studies showing an association between cell phone use and tumor growth, DNA damage, and decreased fertility. They say cancers take 20-30 years to develop and cell phone studies have monitored periods of 10 years or less. They highlight the International Agency for Research on Cancer’s classification of cell phone radiation as a possible carcinogen. Read more background...
Electromagnetic Fields (EMF) are invisible. You can’t see, touch, or feel them, but doesn’t mean they’re not there. As awareness about possible negative effects of wireless energy grows, curiosity simultaneously rises. More and more people ask me about how far they need to be and where the optimal placement is of their routers are for they’re health and safety.
This study elucidates the effect of short (15 days) and long-term (30 and 60 days) low level 2.45 GHz MW radiation induced local stress on the hippocampal spatial memory formation pathway in adult male mice. Researchers observed that 2.45 GHz MW irradiated mice showed slow learning and significantly increased number of working and reference memory errors in RAM task. Further, 2.45 GHz MW radiation exposure increases serum corticosterone level and the expression of CRH, CRH-R1 and i-NOS, while the expression of iGluRs, n-NOS, PSD-95, PKCε, PKA, ERK-p-ERK, CREB and p-CREB decreases in above mentioned hippocampal subregions in a duration dependent manner. “Our findings led us to conclude that 2.45 GHz MW radiation exposure induced local stress suppresses signaling mechanism(s) of hippocampal memory formation.”
The present study investigated the influence of 2.4GHz electromagnetic fields, similar to that emitted by Wi-Fi system, on human brain activity. The presence of radiation had no effect on the energies of alpha and beta band of male subjects, while it reduced these energies of female subjects, resulting in significantly lower energies, as compared to those of males. Delta and theta band energies did not experience any noteworthy effect from gender, radiation condition and their interaction. Conversely, there was a significant interaction effect (gender x radiation) on the energies of alpha and beta rhythms. The present data support the idea that Wi-Fi signal may influence normal physiology through changes in gender related cortical excitability, as reflected by alpha and beta EEG frequencies.
Cell phone radiation may disrupt the functioning of pacemakers. A 2005 study in the International Journal of Cardiology found that mobile phones may have "adverse effects" on pacemaker functions under certain conditions.  According to the US Food and Drug Administration (FDA), radiofrequency energy from cell phones can create electromagnetic interference (EMI) that may disrupt the functioning of pacemakers, especially if the cell phone is placed close to the heart.  The American Heart Association includes cell phones on its list of "devices that may interfere with pacemakers." 
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”.