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Kevin Bomberry uses his cell phone in Burlingame, Calif., Thursday, June 24, 2010. In 2010, Burlingame become the second city in the country to adopt new sunshine laws that would tell customers how much radiation their cell phones would emit before buying them.

By John Boudreau

It's one of the most contentious debate in tech -- are mobile phones hazardous to your health?

At issue is whether the electromagnetic radiation emitted by cellphones is dangerous and even cancer-causing. The verdict is not in, and there are conflicting scientific signals about the long-term risks to mobile-phone users.

But with more than 5 billion people using cellphones worldwide, the answer to the medical and scientific conundrum has global ramifications.

"It's unimaginable today that people will give up cellphones," said Lloyd Morgan, a retired Silicon Valley electrical engineer who is a senior research fellow with the Environmental Health Trust, a nonprofit that researches potential hazards of using mobile phones. His group advocates taking steps to protect against radiation from mobile phones.

"I don't think you have to give up cellphones," he said. "But people have to be educated."

Recent studies about potential dangers from mobile-phone radiation can be puzzling if not disconcerting to consumers.

The Food and Drug Administration says that scientific data so far shows no increased health risks from the use of mobile phones. Last year, a study that looked at more than 300,000 cellphone-using Danes found no evidence that using the device increased their risk of developing a brain tumor. But the World Health Organization, after initially assuring the public that there was no evidence of adverse health effects tied to cellphone use, reversed itself in 2011 by putting mobile-phone use in the same "carcinogenic hazard" category as lead, engine exhaust and chloroform.

And scientists at the National Institutes of Health last year reported that research shows less than an hour of cellphone use can accelerate a person's brain activity near the phone antenna, though scientists aren't sure if that is harmful to users. Meanwhile, a San Francisco ordinance that would force vendors of mobile phones to caution customers that the devices could expose them to hazardous levels of radiation -- vigorously opposed by the industry -- is tied up in federal court.

Though mobile devices have been around for decades, there is still no evidence of an uptick in incidents of brain tumors around the world, said Paul Graham Fisher, professor of neurology at Stanford University School of Medicine.

"It's not an unreasonable concern," he said of worries about radiation from mobile devices. "But right now there really isn't any evidence to say it's a problem."

While the science remains unsettled, cellphone users can take measures to blunt potential hazards -- or at least give them peace of mind.

One group of electromagnetic radiation researchers recently developed a line of smartphone cases with the brand name Pong that redirect 95 percent of a smartphone's radiation away from a user's head. Their claims have been validated by Cetecom, a lab in Milpitas certified by the Federal Communications Commission to test cellphone radiation levels. While company executives do not assert that mobile-device radiation can lead to brain tumors, they say their own concerns about possible hazards led them to develop the Pong cases.

A Pong case "reduces your exposure to radiation by redirecting and redistributing the electromagnetic field that emits from cellphones," said company Chief Technology Officer Ryan McCaughey, who was doing research in cellphone radiation at UCLA before joining Pong. The company, which has six radiation-reducing patents and 13 patents pending, sells cases for the iPhone and iPad, as well as several Android and BlackBerry smartphones through its website, www.pongresearch.com.

"Things like tumors and cancer take a long time to develop," McCaughey said. "It's only recently that cellphone usage has become widespread. It could be 10, 15 years before you start seeing the effects of it in the general public. So we'd like to get ahead of it and reduce exposure before it's too late."

McCaughey also said he never holds a mobile phone to his head while the number he is calling continues to ring. "The highest radiation emission is at the start of a call," he said.

Morgan advocates consumers change their mobile-device behavior much like motorists over the years have embraced vehicle safety measures.

"We've learned to use cars in safer ways," he said. "Imagine if you didn't have safety belts, air bags, dual cylinder breaks."

While Morgan praises the Pong case as an effective safety tool, he cautions that it could give people a false sense of security. Whenever possible, he said, users should keep devices away from their bodies. When people talk on the phone with a headset, he suggests they place the phone as far away from their bodies as possible. And they should not wear phones on their bodies or let children sleep with them under their pillows, he said.

Apple (AAPL) suggests that iPhone 5 users who want to reduce their exposure to the device's radiation use a headset or speakerphone when taking a call, and keep the iPhone "at least 10 mm (about 0.4 inches) away from your body."

For now, Stanford neurologist Fisher said he is more concerned with people who talk or text on a mobile phone while driving than he is about radiation from the device.

"Personally, I don't worry about it," he said of cellphone radiation. But, the physician added, "For someone who is using it constantly, it would be reasonable to use a Bluetooth (headset) and keep it at a distance."

Contact John Boudreau at 408-278-3496; follow him at Twitter.com/svwriter.

cellphone radiation safety Tips

The jury is still out about whether electromagnetic radiation from mobile phones and wireless home phones pose health risks. For those concerned about the potential dangers of using mobile devices, here are safety tips provided by the Environmental Health Trust, a nonprofit that researches hazards of using mobile phones, and Pong, a company that makes smartphone cases that redirect radiation away from the heads of users.
1. When on a call, use a wired headset or speakerphone mode. Use a Bluetooth headset, which emits a smaller amount of radiation, only when talking. When not using the headset, keep it off your body.
2. Place the mobile phone away from your body when on a call.
3. Do not carry mobile phones in pockets of pants or in shirts or bras. Use a belt holster designed to shield the body from radiation.
4. Avoid using a mobile phone in a moving car, train, bus or in rural areas at some distance from a cell tower. Distance from a cell tower will increase the cellphone's radiation output.
5. Turn the mobile phone off when you don't need to use it.
6. Use a corded landline phone instead of a wireless phone, which also emits radiation.
7. Avoid using mobile phones inside of buildings, particularly those with steel structures, which increases the device's radiation output because signals are not as strong.
8. Do not allow children, whose bodies are more vulnerable to absorbing radiation, to sleep with a cellphone beneath their pillow or keep it at the bedside.
9. Do not allow children under 18 to use a mobile phone except in emergencies.
10. When making a call, do not hold the phone to your ear until after the person on the other line answers. The device emits more radiation before a call goes through.