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First, children living near power lines were believed to be at risk for leukemia. Then, cell phones were going to fry our brains. Now, should we worry about Wi-Fi hotzones?
Prompted by citizen concerns , the Toronto Board of Health is conducting a study of the potential health risks posed by Toronto Hydro Telecom's plans to blanket the downtown core with Wi-Fi access points .
A meta-study of the research done in this area is under way, but no field research is planned, says Ronald MacFarlane, supervisor of environmental health assessment and policy at Toronto Public Health (TPH), which delivers programs and services determined by the Toronto Board of Health.
In 1999, TPH conducted a health assessment of human exposure to RF, and the objective of this second study is to provide an update.
"When cell phones were becoming popular in 1999, councilors responded to concerns in their wards and asked us to look into cell phone towers and antennae," he says. "Similarly, people are now concerned about Wi-Fi initiatives, and we've been asked to look into this so we can come back to council with our assessment."
Based on the recommendations of the first study, the Toronto Board of Health adopted a policy of 'prudent avoidance' in 1999 and determined that the level of exposure to radio frequency (RF) electromagnetic fields should be set at 100 times below Safety Code 6, a guideline developed by Health Canada.
"At this point, we're trying to determine if there's a conflict between prudent avoidance policy and actual usage of Wi-Fi," says MacFarlane. "The initial indications are that Toronto Hydro's Wi-Fi RF would be below our recommended level, and there would be no need to alter plans to meet the standard."
He expects the study and its recommendations to be completed and presented to council in early 2007.
To put the issue in perspective, MacFarlane explains that all manner of infrastructure and consumer devices – power lines, radio towers, Wi-Fi routers, cell phones, radio and television, and so on – emit electromagnetic radiation at different frequencies, with varying effects on biological systems.
The electromagnetic spectrum is divided into two major categories, ionizing and non-ionizing radiation.
High-frequency radiation with shorter waves at the ionizing end of the spectrum, such as X-rays and gamma rays, has undisputed detrimental effects on human health. At the borderline between ionizing and non-ionizing is ultraviolet radiation, emitted by the sun, which also has a clear link to skin cancer.
Controversy rages at the non-ionizing, lower-frequency end of the spectrum. At the lowest end are electromagnetic fields (EMF) such as those created by power lines. "The longer the wave, the fewer health effects we tend to find," says MacFarlane. "I know studies have looked at cancer caused by exposure to power lines, but the evidence is weak."
Radio waves, which are used in cell phones, Wi-Fi, radio, television and other consumer devices, operate at a higher frequency than power lines. Microwaves, which are used in radar and ovens, are a sub-set of radio waves, and have an even higher frequency. For RF emissions, there are few studies showing a clear impact, says MacFarlane.
However, he says he is reviewing research conducted in Switzerland that provides some fair evidence of a link between RF emissions from radio towers and sleep disturbances.
"This is something we see quite often in the literature – the RF impact on sleep," he says. "The Swiss changed their laws regulating RF emissions based on that study." But this is just one of a multitude of studies, some with conflicting findings, that the TPH is reviewing and considering to determine the patterns of risk.
Considering the vast array of infrastructure and devices that produce RF emissions, how much more would a Wi-Fi hotzone add to the totality of emissions people are exposed to in downtown Toronto?
"It's like noise," says David Dobbin, president of Toronto Hydro Telecom. "We're already bombarded by radio waves. Our equipment operates in the same frequency and under the same licensing conditions as cordless phones, baby monitors and garage door openers. Cell phone towers operate at 10,000 times the power of our Wi-Fi units, and FM radio towers are 100,000 times."
Tony Muc, a physicist and professor at the University of Toronto's department of public health sciences, agrees with Dobbin's description. "This particular application is yet another specific signal within this sea of electromagnetic fields we live in," he says.
"People have exploited radio waves since Marconi's time. And historically, natural electromagnetic phenomena have occurred as well. Biological entities have been exposed to them forever."
Dobbin points out that Toronto Hydro Telecom's equipment is more than fully compliant with all regulations set by the Canadian government. "Our emissions are a fraction of levels recommended by Safety Code 6 and the Toronto Board of Health. We've even gone so far as to get technical compliance declarations from our vendors such as Siemens to guarantee their equipment puts out less."
But many environmentalists distrust the regulations setting levels of exposure to RF, pointing out that it took decades to establish clear links between the harmful effects of DDT and regulatory decisions to ban it outright, and that no longitudinal studies have been done for RF.
"My response to that is that long-term studies have been happening in society since the advent of electricity," says Muc. "The background level of electromagnetic radiation, or 'electronic smog', has been increasing exponentially since about 1900. If we could look at a spectrum analysis then, we would see little beyond background 'noise', or the hiss of the universe."
Muc also points out that if RF emissions had been banned in Marconi's time, it would have prevented the progress of critical technologies society relies on today, such as the invention of television, radar and wireless.
But the spikes associated with human-generated RF are not easy to quantify or understand. "Take the CBC, for example, the transmission associated with that radio station, at that specific frequency, if we compare the ratio of the level today to 1900, it would be about a million," says Muc. "But that's a narrow window of the spectrum. If you go 10 kilohertz on either side of that band, you would only see an increase of maybe 10 or 100 times."
As a consequence, Muc has strong views on regulatory decisions setting RF levels below Safety Code 6. He says it is an international standard developed by scientists who've done extensive studies to find substantive connections between emissions and risks to human health.
"I think it's terribly misguided, under the rubric of 'prudent avoidance', to undercut standards. I think it's scientific nonsense, it's political, and it's socially short-sighted," says Muc. "So what is the point of the standards in the first place? It's trying to say, 'Because I'm ignorant, I want the number to be this.'"
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