How Much Cellphone Radiation You’re Getting

http://www.wired.com/gadgetlab/2009/09/cellphone-radiation/

Study Reveals How Much Cellphone Radiation You’re Getting
By Priya Ganapati
September 9, 2009

Researchers are divided on whether radiation from cellphones pose health risks or not. Now, one nonprofit organization adds some hard data to the argument: the radiation emission profiles of more than 1,200 cell phone models. The data won’t resolve the debate, but does give concrete information to consumers to help them make their buying decisions.

American cellphone radiation standards don’t make enough of an allowance for safety and ignore the impact of electromagnetic radiation on children, says the Environmental Working Group, which analyzed the radiation emissions from 1,268 cellphones. The group also looked at a number of recent research studies and supporting documentation from the handset makers to arrive at its conclusions.

“We think that based on current standards there’s increased risk of developing brain tumors in long term users — people who have used cellphones for more than 10 years — from radiation in cellphones,” says Olga Naidenko, a senior scientist at EWG, who worked on the report for about 10 months.

The group has created a database of feature phones and smartphones that lists the maximum radiation each of the devices emits. (You can look up your phone’s radiation level using the form embedded in this story, below.)

“We want consumers to take steps they can take to minimize potential risks,” says Naidenko.

About 4 billion people worldwide use cellphones. Researchers have been debating for years on whether the radiation from cellphone use leads to health hazards such as cancer and other illnesses. Perhaps, in no greater proof of how hot the debate is, infomercial peddlers such as Kevin Trudeau and television doctors such as Andrew Weil have declared that cellphone use are one of the risk factors for brain cancer.

More scientific studies have tried to assess both short term and long term impact of cellphone usage. Yet there has been no conclusive evidence so far. That’s because earlier research studies didn’t have a pool of users available who had been on their cellphones long enough, says Naidenko.

“A lot of the studies that came out in 2000 and 2001 only looked at short term exposure, which is about four to five years and they didn’t see any risks from radiation,” she says. “But now that we see results from long term studies, we are seeing more evidence to the contrary.”

Still Naidenko says the EWG’s data doesn’t conclusively prove a link between cellphone radiation and health risks.

Henry Lai, a professor of bioengineering at the University of Washington who has researched the issue in the past, reviewed EWG’s report and says the group is on the right track.

“There’s no solid conclusion right now on whether cellphone use leads to increased health risk,” he says. “But all the data shows cause of concern, and that’s very well brought out in the report.”

Cellphone radiation is transmitted by the antenna and the circuitry inside the handset by sending out electromagnetic waves (radio frequency radiation) to transmit their signal. The radiation emitted by the antenna is not directional, which means that it propagates in all directions more or less equally. Factors such as the type of digital signal coding in the network, the antenna design and its position relative to the head determine how much radiation is absorbed by a user, says EWG.

Other household appliances, such as microwave ovens, emit radiation, but no other device is in such close contact with the human body as a cellphone. “You don’t put your head inside the microwave,” says Lai. “And unless you are standing very, very close to it, the radiation from microwaves is very low.”

The Federal Communications Commission sets the acceptable U.S. radiation standards for cellphones. The effects of the radiation depend on the rate at which energy is absorbed by a mass of tissue. This is called as the Specific Absorption Rate (SAR) and measured in watts per kilogram (W/kg). Most handset makers use private certification companies to test the SAR on their devices.

Based on a recommendation from industry group, IEEE, the FCC limits SAR levels for partial-body exposure (including head) to up to 1.6 W/kg, and whole body exposure to up to 0.08 W/kg. For hands, wrists, feet, and ankles, the limit is up to 4 W/kg, averaged over 10 grams of tissue.

In general, the lower the SAR the better the phone, from a potential health hazard point of view. For instance, Apple’s iPhone 3G has a maximum SAR of 1.39 W/kg when held at the ear. Compare that to the 1.19 W/kg SAR for the iPhone 3G S.

The best phone on EWG’s list, the Samsung Impression, has a maximum radiation of just 0.35 W/kg.

But FCC’s current standards are inadequate, says EWG. FCC standards allow 20 times more radiation to reach the head than the rest of the body, says an EWG representative, and they don’t provide an adequate margin of safety for cell phone radiation exposure.

“The FCC limit for the head (SAR of 1.6 W/kg) is just two-and-a-half times lower than the level that caused behavioral changes in animals (SAR of 4 W/kg),” says the representative. “Thus, the brain receives a high exposure, even though the brain may well be one of the most sensitive parts of human body … and should have more protection.”

There’s also just one one standard for “general population exposure” which is same for adults and children. The FCC also does not have strict enforcement against violators, alleges EWG.

“The U.S. government is not paying enough attention to this health problem,” agrees Lai.

But policy makers in Washington D.C. are starting to take notice. Experts will present evidence at a conference in mid-September, arguing for and against the impact of radiation from cellphones on health, and its implications for public policy. But no cellphone companies or handset makers are expected to be present. Independent of the conference, Sen. Arlen Specter (D-Pennsylvania) is expected to chair a Sept. 14 congressional hearing on cellphones.

Still EWG’s research is just the beginning, says Lai. “It is a not a scientific paper and there are mistakes with over-interpretation and bias in use of some of the literature to support their conclusions,” he says. “But it does serve the purpose of raising awareness of the problems stemming from cellphone use.”