We've come a long way since the days when a child standing in front of a microwave oven was a parent's biggest worry over potential radiation exposure.
The massive growth in cell phones, computers and other electronic devices has prompted a new wave of concerns that children are being exposed to dangerous levels of radiation.
While most of those concerns have centred on cell phones, now a growing number of parents and other citizens are raising the alarm about wireless networks.
The issue taps into common fears that technological innovations come with serious drawbacks. But many leading health organizations and experts say there's no solid science to back up the concerns. It's a major debate that doesn't seem to have a resolution on the horizon.
Wireless networks use radio-frequency signals to allow users to connect to the Internet without plugging their computer into a cable. Wi-Fi is a particular type of wireless local area network.
The issue flared up recently when a group of Ontario parents began urging the Simcoe County District School Board to unplug Wi-Fi networks in its schools amid fears they cause some children to develop nausea, headaches and other symptoms.
The school board said on Monday it would not bow to pressure, however, citing a lack of scientific evidence backing up the link between wireless networks and health risks.
But it's not the first time the issue has come up – and it's unlikely to be the last.
In 2006, Lakehead University in Thunder Bay, Ont., said it would not allow campus-wide installation of Wi-Fi networks. A handful of schools in other countries, such as Britain, have also made moves to limit the use of Wi-Fi networks in order to protect against potential health threats.
Henry Lai, professor of bioengineering at the University of Washington in Seattle, says he believes there is good reason to be concerned over the health implications presented by Wi-Fi technology.
The problem, he said, is that students are exposed to radiation from wireless networks for hours on end while in classrooms, but that little is known about the potential effects this can cause. He added that children may be more susceptible to problems linked to wireless networks because their bodies are still developing.
"[We]don't know much about long-term exposure," Dr. Lai said. "I think we don't know very much about this type of radiation."
Dr. Lai said numerous studies looking at the link between radio frequency exposure and health risks have found some problems, such as headaches, in those studied.
But he added that about half of the studies looking into the subject found no evidence of health effects linked to radio frequency exposure.
Therein lies the problem, according to other experts, who say the lack of good, well-designed studies that examine the issue is helping to fuel public concern.
Although there have been studies looking at the effects of radio-frequency exposure and the effect of electromagnetic fields on health, they aren't large or conclusive enough to close the book on the issue, said David Savitz, Charles W. Bluhdorn professor of preventive medicine and director at the Disease Prevention and Public Health Institute at Mount Sinai School of Medicine in New York.
"I think there's a good rationale for doing research, but so far the best evidence is there's not a hazard [associated with Wi-Fi]" he said.
Daniel Krewski, director of the McLaughlin Centre for Population Health Risk Assessment at the University of Ottawa, agrees that there is no credible reason for Canadians to be concerned over the use of Wi-Fi.
"Based on literally thousands of papers that have been written on health of radio-frequency fields, we have no clear evidence the fields cause adverse human health effects," said Dr. Krewski, who worked on a study released earlier this year that found cell phones do not appear to increase cancer risk in humans.
The World Health Organization says that Wi-Fi networks do not pose a health risk. Health Canada spokesman Gary Holub said in an e-mail that Wi-Fi exposure levels in Canada are "well below science-based exposure limits" and that there is no evidence showing weak radio-frequency electromagnetic energy from Wi-Fi can cause illness.
Part of the problem is that people are prone to be suspicious of any new technology that becomes ubiquitous in a matter of years, Dr. Savitz said.
"I don't want to be dismissive and I don't want to be critical of those raising concerns," he said. "I think it's a very natural question to ask when you modify the environment with technology."