In 1996, Neil Whitfield, a sales manager from Wigan, was given his first mobile phone by his company. "It was introduced as a nice, cuddly friend. It had all of your mates' contact details on it. It was always in your pocket or pressed against your ear," he says.
However, within a short space of time Whitfield, a father of six who was then in his late thirties, started suffering terrible headaches. "Then my hearing deteriorated and I kept forgetting things, which was not like me." A scan revealed he had an acoustic neuroma - a rare brain tumour that grows on a nerve in the brain near the ear.
Without surgery, he was told, he had five years to live. "The specialist asked if I used a mobile a lot. When I said yes, he replied: 'Mobiles will be the smoking gun of the 21st century.' He sowed a seed in my mind." Whitfield, now 56, is one of a growing and vociferous group of people who are convinced that mobile phones are killing us.
A phone, they point out, along with cordless phones and Wi-Fi, works in the same way as a miniature microwave, emitting electromagnetic radiation. Admittedly, this radiation is at too low a frequency to heat human tissue, but there's a large amount of evidence that it could affect the protective barrier between the brain and blood, allowing toxins to enter.
There is also evidence that mobiles could be damaging our immune systems, reducing sperm motility and causing tumours, Alzheimer's, strokes and autism. It's not just individuals like Whitfield who believe this, but a number of eminent scientists and physicians. Two years ago, the International Agency for Research on Cancer (IARC), an agency of the World Health Organisation, published a report, reclassifying radiation from mobiles from category 3, with "no conclusive evidence" of causing cancer, to category 2b - a "possible human carcinogen" - along with diesel exhaust, chloroform, jet fuel, lead and DDT.
In October, the Italian Supreme Court ruled that a businessman's brain tumour was caused by his use of a mobile for five or six hours a day for 12 years, paving the way for a potential host of legal actions from employees against employers.
Yet bodies like Cancer Research UK assure me not to worry. "We think it's incredibly unlikely there's any link between phones and cancer, with the slight caveat it's a relatively new technology so we can't be sure of any long-term effects," says Sarah Williams, senior health information and evidence officer.
To the layperson, the science behind all of this is mind-numbingly complex. For virtually every assertion of risk, there's another asserting no risk. "None of the research has been conclusive. When we do a meta-analysis of it all there's no clear effect in either direction. The studies that show phones don't cause cancer are balanced out by studies that show they do," says Williams.
The anti-mobile lobby disagree. They cite the "precautionary principle" - a statutory requirement in EU law that basically can be translated as: "new technology is guilty until proven innocent".
Until more research is done and phones have been in general use longer, they say it's better to be safe than sorry. Official advice from the NHS is to limit our mobile usage if we want to avoid exposure to radio waves. Children in particular should only use them in emergencies, because if there is any risk, their thinner skulls and developing brains would make them much more vulnerable to potential damage.
Other countries have taken this a step further. France has banned all mobile phone advertising aimed at under-12s, while legislation is being introduced to make it compulsory to sell all phones with earphones. Canada and Russia have also advised caution and the Israeli government is considering printing health warnings on phones, as on cigarette packets. Meanwhile, several countries are implementing or considering a total ban of Wi-Fi in schools. So what is the truth of the matter? Are mobiles really dangerous?
There is no question that some of those sounding the alarm belong to that subset of humanity who see conspiracies everywhere they look. But, investigating the subject, it became clear to me that the arguments against phones are not all the products of paranoid minds. Far from it. The fact is, considering how widespread phones are (more than 5.3 billion mobiles are in use out of a global population of 7 billion) anything that proved they were dangerous would be a highly inconvenient truth. "Mobile phones is an issue we all bury our heads in the sand about," confirms Denis Henshaw, professor of physics and head of the Human Radiation Effects group at Bristol University. "The first mobile phone technology was rolled out without really any consideration for the long-term effects, just like asbestos and smoking.
The government rakes in billions from the technology, in taxes from the mobile phone companies and licensing of the networks. The new generation really doesn't want to know about any potential ill effects." Think of the tobacco companies - says the anti-phone lobby - who concealed the dangers of smoking and the addictiveness of nicotine and supported their position with numerous deceptive studies.
Or asbestos producers who hid evidence that the mineral was dangerous even though tens of thousands of workers were dying from exposure. Mobiles are a multi-trillion-dollar industry, even bigger than pharmaceuticals, and with a sizeable lobbying arm. Nearly every study that's proven mobiles to be safe has been funded by the industry, though scientists involved in such studies point out funds are usually distributed by neutral bodies, so they have no way of knowing the source. Scientists who've discovered displeasing evidence have spoken about threats being issued to remove funding and pressure put on employers to sack them.
But, at the same time, scientists accused of being in cahoots with big business are indignant. Anthony Swerdlow, professor of epidemiology at the Institute of Cancer Research, headed last year's International Commission on Non-Ionising Radiation Protection (ICNIRP) report into mobile safety, concluding there was "no clear evidence" mobiles threatened public health. Online, I find all sorts of attacks ranging from accusations that Swerdlow has shares in the mobile industry (he has a few shares in BT) and doesn't own a mobile (he does). "Where scientists do have a great deal of self-interest is in getting the answers right as far as possible," he says.
"Our long-term careers depend not on money from the phone industry but on having a reputation and track record for doing good science and making sound scientific judgments. If scientists conduct poor studies or make biased judgments, they harm their reputations and damage their careers."
While researching this article, word reached me - from impartial sources - of reputable scientists whose research had led them to banning their children from using mobiles and a neurologist who refused to sleep with her phone charging in the bedroom because she was convinced the electromagnetic fields emitted by mobiles were responsible for the rising number of strokes she was seeing. But they didn't respond to my emails or calls.
Are they reluctant to express their doubts publicly because they rely on the industry to provide them with data, or because - without hard evidence to support them - they don't want to be dubbed crackpot? The crux of the debate hangs on whether this radiation can damage cells. The pro-mobile lobby stress that ionic radiation is associated with cancer because it can break biochemical bonds in the body. A mobile's electromagnetic radiation, on the other hand, has too low frequencies and too weak a signal to be able to heat human tissue and damage DNA molecules.
But many disagree. In 1975, before mobiles were invented, US neuroscientist Allan Frey surprised the scientific community with a paper describing his work on the blood-brain barrier, the vital protective layer between the brain and our blood supply. The barrier is so protective that normally when blue dye is injected into animals or humans, the body turns blue while the brain remains its natural, grey colour. But in Frey's experiments, microwaves pulsed at certain modulations sent dye leaking into rats' brains within minutes.
Rats have very similar brains to humans. This would mean that the brain's environment, which needs to be extremely stable for nerve cells to function properly, can be perturbed in all kinds of dangerous ways and exposed to toxins. Subsequent research has expanded and compounded this work. "People say there's no plausible biological hypothesis for how electromagnetic radiation can damage cells - well speak for yourself," says Prof Henshaw, who is an adviser to Mobilewise, a group that issues safety guidance to children.
"Research is moving so fast, I receive five to 10 papers a day on the effects of radiofrequency. We don't know everything." Prof Henshaw does not agree that primary DNA damage is needed to cause cancer. He cites research into magnetite crystals, that are found in the human brain. Electromagnetic radiation is shown to physically vibrate these particles and there's speculation this could make cells think they're under attack.
"They'll find it stressful and this could affect the mechanism and we know that some cancers are caused by mechanics," he says. There is also a growing school of thought that mobiles can make us more vulnerable to disease. Experiments on birds' cryptochrome, a molecule in their eyes used for navigation, have shown it can be disturbed by the use of radio frequencies, far below those of mobile frequencies. These cryptochromes, also found in humans, help us detect light and therefore have a vital effect on our secretion of melatonin, the hormone that plays an important role in bolstering the immune system.
An increasing number of people are claiming to be "electrosensitive", allergic to the electromagnetic fields that power mobiles, to the point where they've had to quit their jobs or move house, because of the ill effects. "Over the past three or four years, I've seen a dozen or so patients who've had problems because of electromagnetic fields, from those suffering occasional headaches to those left quite severely disabled," says Dr Andrew Tresidder, a GP in Chard, Somerset. "When I advise them to switch off their Wi-Fi routers and cordless phones at night, it often appears to alleviate their symptoms."
Many official bodies, including the Health Protection Agency, dismiss electrosensitivity as a psychological phenomenon. "They haven't seen the patients I've seen," says Dr Tresidder. "Whenever there's anything that disrupts conventional thinking, there's rearguard action trying to dismiss and rubbish any study. I think technology's wonderful and we can't escape it, but I also think in five years' time if we don't pay attention to the evidence, we could be facing a public health disaster."
Cancer Registry statistics for the past decade show that the number of brain tumours has remained fairly static - the period in which mobile phone uptake has been greatest. But this, the doubters argue, is insufficient reassurance as brain tumours have a long latency period of up to 40 years. Although the phone industry strenuously denies its products have any links to cancer, it covers its back, using tiny print to counsel holding the phone at least 15mm from the body. BlackBerry's instructions advise a distance of 25mm and keeping phones away from pregnant abdomens or the abdomens of teenagers.
I still can't contemplate abandoning my phone. But I have dusted off the Bluetooth earpiece I've never used and persuaded my reluctant husband not to leave his phone charging in the bedroom. I'm considering buying a shield, placed in the ear, that is supposed to deflect radiation, but I can find no studies to prove such gadgets actually work. Neil Whitfield's operation on his neuroma was successful, but he was left deaf in his left ear and still gets headaches and facial twitches. He left his job, which relied on mobile use, and now refuses to use a mobile.
"Now, when I haven't a number to give people they think I'm trying to avoid them, or I'm silly, a crank. They think: 'That will never happen to me'. But when you have had a brain operation like me, you err on the side of caution. In my opinion, if phones were a food, they'd long have been taken off the shelves and sent back to the lab for further investigations."