Why does the belief that wi-fi is bad for your health persist in the face of evidence to the contrary? Is it a testament to the power of the human mind, or a failure of rational thought processes? Mike Clay writes.

At a rundown house in Sydney's east lives James McCaughan and his wife Genevieve. Photos of their nine children adorn the walls, physics books cram in overflowing bookshelves, and a giant mesh cage dominates their tiny bedroom.

"I suffer from electromagnetic-hypersensitivity," explains the 60-year-old Catholic. James was a senior lecturer in physics at Australia's oldest and most prestigious tertiary institution, the University of Sydney. That is, until his condition forced him into an early retirement.

"Well, it starts with ringing in the ears, but as the intensity of the source goes up, so does the intensity of this effect," James says. "The penny dropped when I got into the train at Central the other day, and immediately the tinnitus started. I thought: 'Oh, this is not me, this is something outside me.'"

James is part of a growing movement of sufferers and scientists claiming sensitivity to the conveniences of modern life: mobile phones, wi-fi, microwaves and electricity.

"It's a little bit different to a headache, but it's severe pain," he explains. "You're completely disabled when it really gets intense."

He has already spent thousands of dollars fighting his EHS. All the exposed windows are covered in a protective wire mesh and the giant structure in his bedroom is a "Faraday cage", designed to block wi-fi signals. James also wears up to eight metal-threaded skullcaps at any one time, which he says protects his brain from EM radiation: "I've learned, with several layers of this stuff, to actually function well normally. I can pretty well go anywhere."

Carrying a bright orange "electro-smog meter" in one hand, the diminutive cosmologist looks only mildly strange on the streets of suburban Kensington. A passer-by might mistake him for a religious observant with an unorthodox head covering.

James McCaughan wears up to eight metal-threaded skullcaps at a time.

"I try to look as normal as possible, which is almost impossible," he says. "You do get a surprised reaction," admits his wife Genevieve. "But I've learnt to stop worrying about it," laughs James, "and if I'm acting normally then people say, 'Oh, he's normal'."

While Australia mostly ignores EHS, some countries are beginning to take it seriously. Sweden recognises it as a functional disability, but it's diagnosed by patients rather than by doctors. A former head of the World Health Organisation, Gro Brundtland, says she suffers from it. But the official position of WHO is that EHS isn't caused by electromagnetic radiation.

"The mind is a very powerful organ. Once we believe that something is either good or bad for our health, it probably is," explains Ian Lowe.

Ian is an Emeritus Professor at the Griffith School of Natural Sciences. As one of Australia's foremost radiation experts, he sat on the panel that advises the national safety regulator, ARPANSA. "Those who say they are hypersensitive to electromagnetic fields turn out in control tests to be no better than you or I at determining whether there is an electromagnetic field present or not," he says.

As Ian tells it, EHS is another testament to the power of the mind to manufacture the evidence for its own belief. He likens it to the so-called "wind turbine syndrome", where residents living near wind turbines experience debilitating symptoms that they attribute to the wind turbine, despite mounting evidence showing that the technology is safe. "There is a small group of people who experience distress that they associate with electromagnetic fields, but there's no hard scientific evidence that the EMF field of wi-fi or smart meters is causing the problem," explains Professor Lowe.

But fear generates its own momentum and sometimes no appeal to scientific evidence can slow it. In 2013, the European Assembly passed a resolution calling for restrictions on wi-fi in schools. In January this year, the French government banned wi-fi in nurseries and daycares, while a national audit of electromagnetic radiation strength is carried out. And in 2011, the WHO categorised electromagnetic radiation as a Class 2B Possible Carcinogen, alongside chemicals like lead and coffee. While that may sound alarming, Professor Lowe talks down the classification. "What the WHO is saying is that there is a small, but non-zero, possibility of it having a carcinogenic effect, but there is certainly nothing that looks like scientific proof," he explains.

James carries an "electro-smog meter".

At a research facility in Wollongong, Professor Rodney Croft reaches for a mess of electrodes and wires, and then rolls an elastic cap onto a test subject's head. As director of the Australian Centre for Electromagnetic Bioeffects Research, it's his job to investigate the interaction between EM radiation and living systems. "Electro hypersensitive people certainly aren't faking it. The symptoms are very real. They can be extremely debilitating. It's just that there's no relationship between them and the electromagnetic radiation itself," he says.

At a cellular level, electromagnetic radiation can harm and even destroy cells. But humans are more than cells in a test tube. Study after study has concluded that EMF isn't harmful at the levels pumped out by wi-fi and mobile phones, even with the proliferation of devices. According to Professor Croft, the total amount of exposure that you would have in the street might be 50,000 times lower than the lowest level that's been demonstrated to cause a health effect.

But he cautions us against deriding people like James McCaughan or the Spencer family. "It's not a matter of either it is electromagnetic radiation causing the symptoms, or someone is crazy," he says.

Instead, belief in EHS is the natural outcome of rational human behaviour. The human brain always looks for cause and effect relationships. If you get a headache while sitting near a router, you may attribute the headache to that router. Confirmation bias will see that belief grow over time, until the belief becomes so strong that it actually manifests a headache. But it's the fear of the router that's the problem, rather than the router itself. And parents might spread that fear to their children.

"It's entirely possible that well-meaning parents, who are concerned about their children's health, could make them unwell by causing them to believe that their surroundings are a threat to their health," explains Professor Lowe.

Despite the lack of evidence, in 2011 the European Assembly passed a resolution calling for restrictions on wi-fi in schools. In January this year, the French government banned wi-fi in nurseries and daycares, while it conducts a full audit of EMF strength throughout the country. So does Australia, the country that invented wi-fi, need to follow suit?

"Science can never rule out anything, at all. Orange juice could turn out to be the cause of EHS, for instance," suggests Professor Croft. "But if we were to blame orange juice, we'd probably want some evidence. Without any evidence: yes, it's possible. Anything is possible. But I don't think we've got enough reason to change our behaviour, merely because it's a possibility."

Feeding chickens at the Spencer house.

Back in the McCaughan house, James is under no illusions that his condition sits outside the scientific mainstream. "Sometimes you're up against a very sceptical wall," offers Genevieve, "because, 'according to our statistics and the facts and the things we've studied, you shouldn't be suffering this, therefore you aren't.'" But history is littered with examples of technologies that we once thought were safe, only to be proven wrong, years or even decades later: asbestos, thalidomide and DDT immediately spring to mind. "I'm not acting altogether as a scientist," explains James, "I'm acting as a person who is a sufferer and I'm trying to make my life better. So, I can't wait for the science."

James isn't alone in acting without scientific proof. Some are taking drastic action.

In a small house in Sydney's northern suburbs, it's time to feed the chickens at the Spencer house. While their parents hover nearby, five year old Nikkita and eight year old Georgia sprinkle chicken feed on the ground. Suddenly, Nikkita coughs and pauses, looking slightly queasy. "I feel sick," she mutters. This tiny outcry prompts a flurry of parental concern. "Do you want to take her inside, Dan?" asks Oliver. Danielle rushes out with an 'electro-smog meter' and begins to take readings of the signal strength in their backyard. "We live just near a cell tower," she explains.

For the past few months, the Spencers say they have become prisoners in their own home. Danielle rattles off a laundry list of symptoms that she says her four children suffer: sleeplessness, headaches, popping sensations, fatigue, anxiety and heart palpitations. But no amount of visits to the doctor or medical tests could explain them. So they turned to the internet. "And that's when I just found a plethora of information," says Danielle.

Danielle spends hours every day online, comparing symptoms with other sufferers and discussing treatment. The more she learns, the more convinced she becomes. "Radiation is a bit like a bucket: we slowly fill up, our bodies don't get rid of it," explains Danielle, motioning to the mobile phone tower, up the road.

But her greatest fear isn't the mobile phone tower, but the ready availability of wi-fi in their children's school. So in May, the Spencers decided to pull their three youngest out. "I made the decision," says Oliver, "when I discovered that the World Health Organisation had classed wi-fi as a Class 2B possible carcinogen. And for them to be at school, for six hours a day, under an industrial router that's on 24/7, transmitting and receiving ... it was a moral decision."

But experts caution parents against following the Spencer family's lead. "They're doing a great disservice to their children," says Professor Rodney Croft, from the Australian Centre for Electromagnetic Bioeffects Research. "There's certainly huge advantages to school and if we are to deprive children, because of the wi-fi, I think that we're making a very big mistake."

See more about wi-fi sensitivity on Australia Wide on ABC News 24, Saturday 11.30am (AEST) and 9.30am (WAST).

Mike Clay is a reporter with ABC TV's The Drum.

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