Could these be the cigarettes of the 21st century? . . . 'Absolutely'

Oh. This is the more disconcerting because Professor Challis is one of the world’s experts on mobile phone radiation, and chairs the mobile telecommunications health research programme. He has some good news: the first batch of research it has done, soon to be published, confirms that mobile phones are safe in the short term, under ten years. But there is less good news. “It’s encouraging because they found nothing for people who’ve used phones for less than ten years, But there is a hint of something for people using them more.”

Now, being a respected scientist, Professor Challis is keen to emphasise that this “hint” remains just that. A massive European study called Interphone, partly funded by his group, found a slight association between the risk of brain tumours and using a mobile for more than ten years. But the problem is that the number of people involved was so small: more than a decade ago, hard as it is to imagine now, we did not all have handsets glued to our ears. Yes, the few long-term users got more tumours “but it could be by chance”, he says.

Some might leave it there. Given the results so far, scientists could be forgiven for losing interest in the mobile phone safety debate. But Professor Challis can’t let it rest. His knowledge of the major breakthroughs in what causes cancers — smoking, sunlight, asbestos, nuclear radiation — tells him that effects often take a long time to show up. “You can look at almost any cancer where you know what the cause was. You find absolutely nothing for ten years,” he says. The groundbreaking study proving the link between lung cancer and smoking showed a similar delay, he says. “You look at what happened after the atomic bomb. Nagasaki, Hiroshima. You find again a long delay, nothing for ten years. The same for asbestos disease.” So although the many existing studies into mobile phone safety have shown no dangers does not deter him. “The people who’ve done these studies have been cautious. They say, ‘We can’t rule out the possibility’. But I want to know whether it’s there.”

As we both quietly turn off our phones, Professor Challis announced that he is in the final stages — it is hoped to seal the deal in the coming weeks — of negotiating £3.1 million from Government and industry to follow 200,000 volunteers, long-term mobile users among them, for five years. This is the kind of gold-standard study he says has been lacking until now, plotting mobile use against any diseases that volunteers develop, not just cancer, but Parkinson’s and Alzheimer’s diseases and so on. He would like it to go on for ten years, to be on the safe side.

“Because there is a hint and because the professional epidemiologists whom I trust and who do this all the time, feel that there’s a chance that this could be real, they can’t rule out the possibility.”

The number of mobiles in Britain has doubled to 50 million since 2000, and the number of children aged between 5 and 9 using mobiles has increased fivefold. If, as Professor Challis fears, mobile phone risks could be slow to show up, then what about today’s children? Some scientists have said there is no cause to believe mobiles affect them in any way differently to adults.

Professor Challis disagrees. “We all know that if you’re exposed to sunlight as a kid you’re much more likely to get skin cancer than if you’re exposed as an adult. That’s why children should be covered up if you’re out in the sun all the time. We know that they react differently to ionising radiation, to radioactivity and gamma-rays. They are more sensitive to pollutants.

“Now we have absolutely no idea whether they’re different in reaction to this sort of radio frequency. But all we do know is that there are reasons why they might be. And kids are using mobile phones a lot, fortunately mostly for texting, but they’re still nattering away.”

This is why he plans a study following the fate of mobile-using children: “We want to look first at the possibilities of what are called soft outcomes. Kids’ diseases. Memory retention. These things seem highly improbable, but . . .”

His advice for now? Play safe by not giving your child a mobile before secondary school. Then encourage them to text rather than make calls.

Now our heads are beginning to throb. Is the professor really saying that the mobile phone could — just could — turn out to be the cigarette of the 21st century? “Absolutely.”

We put it to him that ever since Marconi, we have lived with radio waves from TV transmitters, radios and radar installations. “Some people say, why do you even start the research? And I say, nobody can know what is going to cause us problems or not. This is the first time anyone’s stuck a transmitter right near to their ear, apart from a few people using walkie-talkies. And the exposure you get from mobile phones is thousands — tens of thousands sometimes — times more than you get from a television broadcast or a mobile phone mast.

“And about 40 per cent of the radio energy of that phone is absorbed into your head.” Perhaps, but still no one has come up with a plausible medical explanation of how mobile phones could cause disease, a fact he readily admits.

“But my take on this, before I got involved in my research area, was in low-temperature physics. I have lived through all sorts of exciting things where no theory was ever produced on something that turned out to be very exciting. The fact that we haven’t got a mechanism means nobody has managed to think of one. That doesn’t mean there isn’t one.”

Professor Challis helps his case by being as sceptical about the dangers of masts, and wi-fi, as he is concerned about possible risks of mobiles. Pinging an e-mail through wi-fi typically exposes you to 200 times less radiation than talking into a mobile phone, he says. “I wouldn’t be worried if my grandchildren were exposed to wi-fi in the classroom.”

Even if a risk is found, people will not have to stop using mobiles, maybe just reduce their exposure to them, such as using a hands-free set, perhaps with a “ferrite bead” (a special metal clip) to block any radiation getting to your ear.

The final charge that sceptics will throw is that he wants to get his organisation more funding. “My personal interest would be to go sailing.” At 73, he is not far from retiring. “I do it because it’s worthwhile.”

We ask him if we can call him on his mobile later, on his way home. Difficult, he says — he keeps it switched off.

Because of health fears? “No, I don’t like people rabbiting away on trains. I try not to rabbit away on trains.” We are about to sigh with relief, and then he adds: “As far as health is concerned, bear in mind I’m not a young guy. Rather different from being a child or a young person or people of your age.”

Tips to cut risk

“I do feel if we can hold off children using mobile phones at least until they get to secondary school, that would be a good thing”

“If we encourage children to text instead, where you’re only going to get exposed significantly when you’re actually talking to the phone, that’s another good thing”

If children are using a laptop on a wireless network, put it on a table or the floor: “I don’t think kids should put laptops on their knees”

If you are using a hands-free system with a wire, some radio frequency may be passed to your ear, but “it’s so damned easy to put a cover of ferrite beads or something similar in that wire to stop it getting out”

If you are concerned about intensive mobile phone use, consider putting it a short distance away. A short gap dramatically reduces exposure: “Quite a lot of people use a mobile in place of a landline. Why not stick it on your desk, in your handbag or put it on the floor?”