All that research has taught us that at high frequencies, electromagnetic radiation can promote tumor growth and cancer. The sun’s ultraviolet rays and their links to skin cancer are one example. Even at lower frequencies, very high levels of electromagnetic radiation exposure can hurt you. “But we’re talking skin burns, not cancer or tumors,” says Kenneth Foster, a professor of bioengineering at the University of Pennsylvania.
Sixteen years later, cell phones -- with 6 billion subscriptions worldwide and counting -- have revolutionized how we communicate. The technology that powers them has changed just as dramatically. Today’s smartphones vibrate, rock out, show high-def movies, make photos and videos, issue voice commands, check email, go underwater, navigate with global positioning systems and surf the web in 3-D. They sport dual core processors and batteries that let you – or your kid -- talk for close to 20 hours. (The StarTac maxed out at just 3 hours.)
As a result, it is observed that the long-term exposure to Wi-Fi 2.4 GHz Radiofrequency radiation caused an increase in the DNA damage of the brain, liver, kidney, and skin tissue of rats, but this increase was not significant. Therefore it is determined that the long-term exposure to Wi-Fi 2.4 GHz Radiofrequency radiation does not cause the DNA damage of the brain, liver, kidney, and skin tissue of the rats. However it is concluded that the long-term usage of 2.4 GHz Radiofrequency wireless internet providers could cause a potential risk of DNA damage in the testes.
This study was an in-vitro pilot study which established the effect of radiofrequency radiation from 2.4 GHz laptop antenna on human semen. A test of significance between results of semen parameters using Mann-Whitney U- test at 0.05 level of significance showed a significant effect of RFR exposure on sperm concentration, motility and morphology grading.
Research on glioma brain tumors shows the average latency period is 20-30 years.  Although cell phones were introduced in 1983, it was not until 2003 that over 50% of the US population had a wireless subscription, so the 20 year mark for mass cell phone use has not yet been reached.   The May 17, 2010 INTERPHONE study, the largest study ever to examine possible links between cell phones and brain tumors, concluded that overall there was "no increase in risk" for glioma or meningioma brain tumors,  but the average user in the study had less than eight years of cell phone exposure.  In his review of the INTERPHONE study results, Dr. Rodolfo Saracci stated that "none of today’s established carcinogens, including tobacco, could have been firmly identified as increasing risk in the first 10 years or so since first exposure." 
I have just received my wifi connection home first time In my life and I can tell you it has not been a pleasant experience since installation. In the beginning my wifi router was emitting horrible smell that made me feel sick and I also experienced some kind of invasion on my body and head I did not know how to call it until the technician described it for me as being radiations. At night my brain was suffering noise and my vision freckles like that of after tv trasmission would end in the past. I do not mean to be funny but this is the best way I can describe it. And the previously described is also combined with noise in the ears. Now the smell is a bit less but it is still there. I am able to sleep but with all that noise in my head. I also suffered feeling as if very tired although I do not know if it was all due to the wifi. After that I am busy looking for safer internet connection but have not found any yet especially after I read about the hazards.
Since children’s skulls are thinner than adults’ and their nervous systems are still developing, researchers believe they may be at a greater risk for cell phone-related cancers. They’ll also be exposed to the potentially harmful radiation significantly longer than their parents’ generation. Until more is known about the possible carcinogenic effects of cell phone use, curb your kids’ cell phone habits by encouraging texting or using a landline instead—if they can actually recognize a landline anymore, that is.
Lloyd’s precautions are good ones, although he doesn’t cover cell phone use. I’ve worked on cellular telephony for the last 18 years, coming to the same conclusions about cell phones about ten years ago, the science had gotten conclusive enough for me, as I doubted at first that they could be a problem. As you may have heard, you don’t want to talk on them next to your head if you can help it, use speakerphone mode or wired or Bluetooth headset (BT is very low power, usually keeping itself around only a milliwatt, although wired or speakerphone is better). Don’t park it all day long on any body parts you want to keep cancer-free, especially the pelvic and pectoral regions (trying to keep it classy here). I wouldn’t advise living within a third of a mile of a cell phone tower, or within a mile of a TV tower, if you can help it. Best wishes all.
WiFi radiation exposures drop off significantly with distance (called the inverse square law). Many routers have a strong enough signal to maintain a connection up to 100m from the router. Make sure you put as much distance between you and your wireless router as you can without diminishing the efficiency of your connection. Remember: walls don’t stop wireless radiation, never situate a wireless router behind a bedroom wall.
Since the development of communication devices and expansion of their applications, there have been concerns about their harmful health effects. The main aim of this study was to investigate laptop thermal effects caused by exposure to electromagnetic fields and thermal sources simultaneously; propose a nondestructive, replicable process that is less expensive than clinical measurements; and to study the effects of positioning any new device near the human body in steady state conditions to ensure safety by U.S. and European standard thresholds. A computer simulation was designed to obtain laptop heat flux from SolidWorks flow simulation. Increase in body temperature due to heat flux was calculated, and antenna radiation was calculated using Computer Simulation Technology (CST) Microwave Studio software. Steady state temperature and specific absorption rate (SAR) distribution in user's body, and heat flux beneath the laptop, were obtained from simulations. The laptop in its high performance mode caused 420 (W/m2 ) peak two-dimensional heat flux beneath it. The cumulative effect of laptop in high performance mode and 1 W antenna radiation resulted in temperatures of 42.9, 38.1, and 37.2 °C in lap skin, scrotum, and testis, that is, 5.6, 2.1, and 1.4 °C increase in temperature, respectively. Also, 1 W antenna radiation caused 0.37 × 10-3 and 0.13 × 10-1.
“There are 25,000 brain tumor cases in India’s Andhra Pradesh and Telangana states, and most of them are attributed to excessive use of cell phones, as per a recent medical survey”. Girish Kumar said that World Health Organization warned of increasing risk of cell phone brain tumor and cancer cases caused by the use of cell phones and location of cell towers in residential areas.