How cellphones work
Bear with us here as we go through some basics you may already know: Cellphones are essentially portable radios, receiving from and transmitting to cellphone towers using radio frequencies (RF) that, in terms of their range, fall between those from FM radios and those from microwave ovens.
RF from cellphones can penetrate your body. The depth and the amount you absorb depend on how close you hold the phone to your body and the strength of the signal. The RF energy increases the farther you are from a cell tower and depends on any obstacles that block it, which means it can vary within a single call.
Health Canada has set a maximum specific absorption rate (SAR) of 1.6 watts of RF per kilogram of body weight as a level that people can safely absorb. ‘This value is 50 times lower than the level that would start to cause a health effect,’ says Robert Bradley, director of the Consumer and Clinical Radiation Protection Bureau at Health Canada. ‘This means that they’re safe for users regardless of age or cumulative use.’
Health concerns about cellphones
So there’s nothing to worry about, right? Not so fast. Some scientists are concerned about heavy cellphone use over many years, especially the future effects on today’s young users. And several studies indicate that long-term use is associated with an increased risk of slow-growing brain tumours and an ear nerve cancer. Most often cited is research by Lennart Hardell, a professor at the University Hospital in Orebro, Sweden. His work is epidemiological: It’s based on analysis of the distribution of a disease, but does not establish direct cause and effect. The studies show a 20 percent increased risk of malignant glioma (brain tumours) in ‘heavy’ cellphone users’roughly 2,000 hours over 10 years (about 30 minutes per day). The risk increases to 200 percent for tumours on the side of the head mainly used during calls.
‘We need research on more long-term users to understand the full risks,’ stated Hardell in a release by the BioInitiative Working Group (BIWG), 14 scientists from around the world who feel existing public safety limits are inadequate. Hardell found a five-fold increase in the risk of brain tumours developing in people who started using cellphones before age 20. (Some scientists contend that children may be especially vulnerable because of their smaller head size and thinner skull bones.)
Martin Blank, a BIWG co-founder and an associate professor of physiology and cellular biophysics at Columbia University in New York, maintains sufficient evidence’BIWG’s report, updated in the March 2009 issue of Pathophysiology, looks at 15 studies’already shows that RF electromagnetic field levels now considered to be safe can damage human DNA. ‘RF is a potential biological agent,’ says Blank. ‘The energy is weaker than microwaves, but essentially the same.’ BIWG recommends that standards be set 1,000 times lower than current ones. For children, Blank suggests that a cellphone be used only as a tool.
Health Canada, the National Cancer Institute in the U.S. and the World Health Organization (WHO) point out that these studies do not show a consistent link to cancer, and cite other research that shows no increased risk. Within the past year, however, Finland has recommended that children favour texting, Israel warned its citizens to stay at least half a metre away from chargers (which emit greater RF) and France has proposed legislation that would ban advertising of cellphones to kids under age 12 and ban the sale of phones for use by kids under six. Canada and the United States have not taken such steps. (Indeed, a U.S.-based company called Firefly Mobile says on its website that it’s ‘the mobile phone for mobile kids.’ It targets kids and tweens, featuring colourful phones with oodles of games and two large buttons’with the icon of a woman or a man’so a child can quickly reach mom or dad.)
Clearly, people need some definitive answers. Yet the evidence many governments have been waiting for’findings from the Interphone Study Group, WHO’s 13-country study on cellphone use cancer risks’is unlikely to provide those answers. A final paper, which was expected last fall, has been delayed with reports of disagreements among the researchers. Early findings have been faulted by some scientists for poor-quality data (usage rates are dependent on participants’ memories’a criticism of many epidemiological studies). And none of the Interphone studies included children.
The bottom line
To date, Bradley’s Health Canada laboratory has not been able to reproduce the results of studies that claim a causal link between RF and DNA damage. ‘The reassuring aspect is that if there is a cancer risk, it’s awfully hard to find,’ he says, and adds that there isn’t enough knowledge to provide any specific advice: ‘Limit use to five minutes a day? Two hours a day? You have to have something concrete to say.’
Not everyone agrees with a wait-and-see approach. ‘While there’s a lot of uncertainty in the science, it’s important to provide information to the public so people can make their own decisions,’ says Loren Vanderlinden, supervisor of environmental health assessment and policy at Toronto Public Health, which has advised limiting cellphone use. ‘We call it ‘prudent avoidance.”’
Ways to limit exposure
‘ Limit children’s use of cellphones to texting and emergencies.
‘ Spend less time talking’text or use a land line.
‘ Use a headset or earpiece. These emit almost zero RF. Carry your cellphone in a purse or backpack (of course, RF is only an issue when the phone is turned on).
‘ Choose a cellphone with a low SAR. To find the value for a specific model, go to mmfai.org/public/sar.cfm.
‘ Avoid products claiming to reduce RF exposure, such as phone shields. There is no evidence that they work, and they may interfere with the operation of the phone.
What do you think? Do you limit your kids’ use of cellphones, or your own? Share your thoughts in the comments.
This article was originally titled "The Truth About Cellphones," in the September 2009 issue of Best Health. Subscribe today to get the full Best Health experience’and never miss an issue!’and make sure to check out what’s new in the latest issue of Best Health.