Worried about your smartphone giving you cancer? You shouldn't be. Although these devices do emit radiation, experts say it isn't nearly enough to permanently damage cells or raise cancer risk – even for people who use them constantly.

Still, it's no surprise that many people are concerned about this. It's been proven that high-dose radiation from X-rays, chemotherapy, and other sources can cause DNA damage and increase cancer risk, and some science suggests that chronic exposure to lower-potency radiation may be health-harming over time.

And there's no question that we're exposed to more radiation today than even five years ago, since our reliance on radiation-emitting mobile devices has risen so sharply. In 2002, there were 140 million cell phones in use in the U.S., and by 2012, there were a whopping 326 million, according to the Cellular Telecommunications and Internet Association.
Even so, experts say the amount and kind of radiation emitted by smartphones isn't a health concern. "Several studies have looked at how cell phone use impacts our health, specifically whether it can cause brain cancer," says Ken Portier, a researcher with the American Cancer Society. He says brain cancer is the top concern since we hold our phone close to our heads, so the tissues in and around the brain absorb the most radiation. "However, even in people who use their phones eight to 10 hours a day, seven days a week, studies have shown almost no increased risk of brain cancer," says Portier. "No other adverse health effects have been linked to cell phones either. Research has established no impact on cognitive function, heart rate, sleep, or blood pressure."

According to Portier, this is because smartphone emits nonionizing radiation, which basically just generates heat and isn't powerful enough to damage cells. By contrast, radiation from chemotherapy and gamma rays is ionizing, meaning it does mess with cells and potentially causes cancer. Portier even thinks that our radiation exposure from cell phones may be decreasing. A few years ago, his team researched the various amounts of radiation emitted by different phone models. He says that early-generation smartphones like BlackBerrys were roughly 10 times more powerful than some other models, which means they also emitted more radiation. But now that we've largely moved on from BlackBerrys, most of the phones we use today, which tend to be lighter and hold power longer, likely generate less radiation.

Also, hands-free head sets and ear pieces emit way less than the actual phone, Portier says, so the fact that more people today use these tools more often means that much less radiation exposure.(from YAHOO! NWES)