Chemistry gives us the stuff of life - not least drugs, disposable nappies and chewing gum - but public suspicion threatens its future, John Emsley tells Geoff Watts.

Type the phrase "chemical-free" into Google and you conjure up 95,900 portals to a way of life in which chemicals play no part. A world of chemical-free insect repellent, weed control, Christmas trees and hair colouring; of chemical-free sunscreens, maple syrup, water purifiers and furniture; of cotton, skin care, lawns, swimming pools and pain relief.

The view of chemicals as nasty artificial things to be avoided at all cost - as in "I don't take prescription medicines because they all have chemicals in them" - is widespread. Yet, what are chemicals? Simply the products of chemistry: the study of elements, compounds and the laws governing their interaction and combination. As everything in creation is made of elements and compounds, including our own bodies, everything is a chemical.

To writer and chemist John Emsley, the notion of a mythic world free of chemicals and filled only with "natural" substances is as depressing as it is nonsensical. "We've destroyed the word 'chemical'," he complains.

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"Everyone now seems to think it means toxic or dangerous or harmful." He talks of the suspicion with which shoppers view the list of E-numbered ingredients on food packaging. "People think it's a warning. I point out that something gets an E-number only when it's been approved for use in every country in Europe. That's the definition." E300, for example, is vitamin C. Gosh, just think... good old vitamin CI a chemical!

Emsley's new book, Vanity, Vitality and Virility , is his contribution to attempts to reintroduce reason into public discourse about chemistry and all its works. "There are about 40 everyday chemicals in the book. They come into our lives without people realising their sources. All the products I talk about - lipstick, sun block, shower cleaners - are ones we use every day without querying the fact that these are products of the chemical industry."

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How did chemistry acquire such a negative image? In part, it's a victim of a disdain for science in general. And there is also what some commentators see as a worrisome erosion of reason, and its replacement by feeling and emotion, as ways of engaging with the world. In chemistry's case, there are also more specific factors. Time was - and not so long ago - when the chemical industry was less than fastidious over what it did with its waste.

"When you go back to the 1950s," Emsley admits, "what the chemical industry didn't want, it simply threw in the local river." In the 1960s, Rachel Carson's Silent Spring hammered a nail in the industry's coffin. So did thalidomide. And, more recently, the visible indifference to environmental damage shown by many eastern European chemical plants has hardly helped.

Paradoxically, the science has also been a victim of its own success. In the 1950s, analytical chemists could detect substances present at concentrations measured in fractions of 1 per cent. Now it's possible to trace them down to parts per trillion. There comes a point at which pretty much everything is contaminated by something. Legitimate concern becomes a chemiphobic obsession. How many of these instances of micro-pollution amount to a hill of beans is a matter of dispute.

Emsley still thinks that if Greenpeace and its like didn't exist, it would have to be invented. But he does wonder how it is that scares acquire lives of their own, running and running, when time, evidence or both seem to have demonstrated that the hazard is negligible. "The original scare story may hit the headlines," he reflects, "but three years later, the retraction gets three column inches." That said, he is also critical of researchers who hype their results to generate publicity.

But what troubles Emsley most these days is the effect of this poor standing on the future of chemistry itself. According to opinion polls commissioned by the Chemical Industries Association, chemists are rated on a par with secondhand car salesmen. Small wonder that many university chemistry departments face a crisis of student numbers. Although acutely aware of the problem, Emsley sees no simple remedy. He speculates briefly on the value of soap operas in changing public perceptions. Sadly, the chemist as hero remains less plausible than the chemist as villain.

Emsley's worries about his discipline are in sharp contrast with the obvious satisfaction it has given him personally - from childhood onwards.

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Like many other children, he had a chemistry set. But that was just a beginning. "I remember dissecting fireworks and taking the chemicals out to see how they were made. And then making bigger fireworks."

He became really serious about chemistry at his grammar school. "The subject just clicked with me from the word go. I loved it. I don't know why. My father was an overlooker in a textile mill. I do remember him saying: 'Go to university, do chemistry, get a job with ICI and you're made for life.' In the 1950s, ICI was churning out all these new products. It was the future. It was transforming the world."

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His career began conventionally enough with a PhD at Manchester University followed by more than 20 years of research and teaching at King's College London. But at the end of the 1980s - "my midlife crisis time" - he took early retirement. He'd been writing regular pieces for New Scientist since 1976 and by 1980 was its chemistry consultant. But he'd been told that "all this popular science writing isn't helping your academic career". He stopped writing for a year, but he missed it. Early retirement allowed him to take up writing full time.

He didn't wholly cut his links with academia. In 1990, he became science writer-in-residence at Imperial College London's chemistry department, editing its regular newsletter and performing other publishing tasks. The department's interest was in raising its profile among alumni, prospective students and potential grant-givers. The benefits to Emsley went slightly further. As he points out, a freelance writer trying to make contact with media-shy researchers has a head start if he can introduce himself not as John Emsley, journalist, but as Dr Emsley of Imperial College.

In 1997, he signed a five-year contract to perform similar duties as chemistry science writer-in-residence at Cambridge University. That's run its course, but even now he still lays claim to a half share in a small room at Imperial - more a store cupboard of books and files than what it once was (a pint-sized laboratory) - and he and his PC huddle in one corner. How much does he enjoy writing? "It's in the blood almost. When I've not done it for a time, I almost feel a craving." And not only writing: "I do like to stand in front of an audience and talk."

Which, before too long, he will no doubt be doing about Vanity, Vitality and Virility. The last word of the title, incidentally, was supposed to be Viagra, but the lawyers advised against it. No matter; the intimate details of its chemistry are there in the book for those who don't already know them.

Personally, I found the chapter on polymers more revealing. The chemistry of the super-absorbent polymers offers intriguing insights into the rise of the disposable nappy industry. Equally absorbing is a section on the isobutylene-isoprene copolymer, polyisobutylene, polyvinyl alcohol and other such hydrocarbon polymers. Or, as we non-chemists like to call the stuff when we buy it, chewing gum.

Vanity, Vitality and Virility: The Science behind the Products You Love to Buy is published this month by Oxford University Press, ?18.99.

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