The amount of electromagnetic radiation emitted by cellphone handsets that penetrates your body is based largely on how close the device is to your head during calls, the number of phone calls you make, and how long your calls last.

In Depth Cellphones
How wireless technology can affect the body

By Nicole Tomlinson
November 22, 2007:-   Most people don't think twice about talking, texting or e-mailing on the go �?sending waves of radiation into the environment, and their bodies, as they stay connected through mobile technology.

The bulk of research into cellphones and their base towers has found no definitive evidence that short-term use poses significant health risks to humans. So policy makers have given industry the green light, allowing the use of wireless gear to explode around the world.

Now that the technology has been widely used for a number of years, researchers have turned their attention to exploring possible effects of long-term exposure to the electromagnetic fields they emit. Two groups have found that more than a decade of cellphone use may pose safety issues for humans, according to a report from the European Commission that was published in March, and two other research roundup papers recently published by Occupational and Environmental Medicine.

The report, issued by the Scientific Committee on Emerging and Newly Identified Health Risks, cites several studies on the topic published in the last five years that have found an increased "relative risk estimate" of both cancerous and benign head tumours.

But the document also said the majority of papers on the topic reported no connection between 10 years of mobile phone use and disease. Supporting data on both sides is limited. Health Canada, the Food and Drug Administration in the United States, and the European Union have based their cellphone regulations on the majority of evidence available so far.

Who's using wireless
 According to Health Canada, the FDA and the EC report, the bulk of scientific research has found no significant links between cellphone use and adverse health effects. (Bullit Marquez/Associated Press) Cellphone technology is already firmly ingrained in Canadian culture �?especially in urban centres. About 19.3 million of us, or more than 60 per cent of the population, subscribed to wireless phone services at the end of September 2007, according to The Canadian Wireless Telecommunication Association (CWTA).

The CWTA estimates 70 per cent of people in major urban centres in Canada are using wireless telecommunications technology, with some areas approaching the 80 per cent mark.

Canadians also love to talk on their mobile phones. Last year we clocked an average of 411 minutes a month on our handsets, coming in fourth out of 53 countries around the world in terms of use, according to data released by Merrill-Lynch. Only those in India (432 minutes per month), Hong Kong (460) and the U.S. (832) chatted more on their cellphones than Canadians.

Placing voice calls on mobile devices rather than e-mailing or texting raises potential health concerns, because a user’s level of exposure to radio-frequency energy is higher during a call. Talking on a handset takes a lot more power than sending and receiving texts or other information, and the handset is usually held closer to your body when you're speaking than when you're using the device for other purposes.

The amount of radiation �?in this case, electromagnetic waves emitted by handsets �?that penetrates your body is based largely on how close the device is to your head during calls, the number of phone calls you make, and how long your calls last.

Is it all in our heads?
According to Health Canada, the FDA and the EC report, the bulk of scientific research has found no significant links between cellphone use and adverse health effects.

However, a few papers listed in the report, as well as a review of 18 studies published by Occupational and Environmental Medicine in April, suggests more than 10 years of cellphone use increased the risk of:

• Glioma, a type of cancer that affects the central nervous system and can manifest in the brain; and
• 
  Acoustic neuromas, a slow-growing non-cancerous tumour that develops around a cranial nerve that attaches to the inner ear, resulting in hearing loss.

According to the EC document, research has also found that radio-frequency energy can cause local temperature changes in the brain, alter protein structure and expression, and affect neurotransmitter biochemistry.

The possible influence of cellphone radiation on human behaviour, such as attention and memory, was also documented in the report, and in another paper published by Occupational and Environmental Medicine in October, which reviewed 19 studies.

The EC report also reviewed previous research into a possible link between mobile phone use and brain tumours in children, and concluded that further investigation into the issue is "warranted."

The committee cited widespread [cellphone] use �?among children and adolescents, relatively high exposure to the brain and few relevant studies that address the possible effects as reasons for the recommendation.

EMF
With researchers lacking the timeline, and therefore the data, to take a definitive stand on the long-term health effects of mobile telecommunications, some organizations, such as members of The BioInitiative Report, the European Environment Agency, and The EMR Policy Group, say current laws regulating the use of electromagnetic devices should be reconsidered.

The position, known as "the precautionary principle," says that if we can't be certain something won't have a negative impact on our health, we should err on the side of caution.

But according to Tony Muc, an assistant professor at the University of Toronto and the chief physicist at Toronto-based Radiation Health and Safety Consulting, we actually know a lot about the principles behind mobile phone technology.

"As far as cellphones and cellphone-like technology is concerned, the relevant electromagnetic radiation has been studied since microwave ovens came on to the scene," he said.

"To say that cellphones now are a relatively unstudied phenomenon is simply not true, as far as the underlying radiation is concerned."

Cellphone technology operates at 450 megahertz, 900 megahertz, and 1,800 megahertz �?frequencies that are in the same region as microwave ovens, which generally operate at 2,450 megahertz. These devices, along with TVs, radios, and radar, emit electromagnetic waves that are non-ionizing �?which means they lack enough energy to break chemical bonds in the body. So electromagnetic field radiation, unlike ultraviolet light, X-rays and Gamma rays, doesn't cause ionization or radioactivity in humans.

"We’ve had microwave ovens in our homes for more than 40 years now, and the prevalence has increased in North America �?they’re virtually everywhere now," Muc said.

"The operating frequency is in the same region, and there hasn't been any particular influence attributed to them, even though people have looked."

A matter of power
So if cellphones radiate waves similar in frequency to microwave ovens, and we hold handsets close to our heads, could we be cooking our craniums?

According to the United Kingdom health protection agency, the maximum temperature rise in the head due to absorption of energy from a mobile phone is around 0.1ºC �?a far cry from what a microwave oven does to a frozen dinner.

Muc explained the difference lies in the amount of power each device uses. Most cellphones operate at power levels ranging from 0.2 to 0.6 watts, according to the World Health Organization.

The average household microwave generates 500 to 1,000 watts, according to the British Columbia Centre for Disease Control.

Muc said that with a cellphone, "you have this little source powered by a battery that you’re holding within a centimetre of your head, that's about 1,000 times weaker [than a microwave oven].

"So the net effect [of a cellphone] is still negligible �?just like the net effect of the microwave oven is negligible, because even though it’s stronger, you’re further away."

It can be argued that while electromagnetic fields, the basis for cellular communication, have been studied extensively, mobile technology is unique because handsets are used in such close proximity to our bodies. Nevertheless, Muc says decades of research into electromagnetic fields have given us enough information to reject "the precautionary principle" as the best course of action when it comes to wireless communications.

"'As far as the scientific evidence is concerned, there is no sound basis for a public policy to either restrict, or much less ban, the use of cellphone technology," he said.

"Human society, if they want to do that, has every right and privilege to do it �?that’s what freedom is �?but to call it science is nonsense."

From:  [http://www.cbc.ca/news/background/tech/cellphones/health.html]

Note:  The original article contains a number of links into more indepth exploration.