Science: Catalysts for good, not evil: Many people fear artificial sweeteners and nitrates in tap water, but chemicals are beneficial for all, argues John Emsley

IF ONLY chemicals could be banned, what a cleaner, healthier, happier world it would be] That seems to be the sentiment of many people in Britain. And it's not surprising, because we hear so many stories of the threats that chemicals pose to our well-being. This month it is dioxins, 'the world's deadliest toxins', that are spewing from chemical plants and incinerators.

Yet chemicals in the main save human lives and make those lives more bearable. Antibiotics cure disease, fertilizers and insecticides increase food supplies, painkillers relieve suffering. Nor are humans the only ones to benefit. The next time you dab a spot of perfume behind your ears or splash on your aftershave, you will be using the products of the chemical industry not those of the animal world.

This switch to using artificial fragrance molecules has saved the lives of tens of thousands of musk deer each year. Hunters used to kill the male for a gland - which secretes a chemical that the doe finds irresistible - and the world's perfumers paid them handsomely for it. In 1900, 50,000 musk deer were slaughtered; by 1978, musk extract was worth three times its weight in gold.

Today there are about 400 commercially produced perfumes for women and 300 for men. Quest, one of the world's leading fragrance manufacturers and based in Kent, makes many of its components. According to Quest's Dr Charles Sell, modern scents are a blend of natural and synthetic ingredients. The smell may be described as April Fresh on a bottle of fabric softener, or Japanese Garden on a toilet cleaner, but these are not derived from the flowers that bloom in the spring, or the cherry blossoms of a Shinto shrine. They come only from chemical plants.

Yet there are many who believe only evil of the chemical world: these I call the chemically-challenged. These people scatter their curious, but commonly held theories everywhere. They believe that saccharin causes cancer, that white bread has no fibre, that PVC contaminates food, that blue-baby syndrome is caused by nitrates in tap water, and that lard consists mostly of saturated fat.

There have been some terrible incidents involving chemicals, such as thalidomide, Bhopal, and the escape of mercury at Minamata, Japan. But none of the chemicals which have been the focus of recent scares are in this class. It is possible to count on the fingers of one hand the number killed by dioxins, artificial sweeteners, nitrates, PVC and food additives. In contrast, you would need all the fingers on the hands of every anti-chemical campaigner to count the number of deaths caused by just one outbreak of chemical phobia. In 1991, the Peruvian authorities were persuaded by environmentalists to stop purifying public water supplies with chlorine because the campaigners said it formed cancerous chemicals. The result was 500,000 cases of cholera and 10,000 deaths.

For some chemicals there can be no substitute. The nitrate found in the much-maligned 'artificial' fertilizers is exactly the same as that in an 'organic' fertilizer. Plants need nitrate and make no distinction between the inorganic or the organic form. And they are equally happy with the nitrate from atmospheric pollution.

This nitrate falls as rain and comes from the nitrogen oxides formed when we burn coal, oil, petrol or gas. According to Dr Keith Goulding, of the Rothamsted Experimental Station in Hertfordshire, the crops of organic farmers receive as much as 20kg of such fertilizing pollution per hectare per year. Experiments at Rothamsted have also proved that artificial nitrates are often not the main cause of nitrate in rivers and drinking water. That nitrate comes mainly from natural sources in the soil.

Too much nitrate can affect our health, and the World Health Organisation sets a limit of 50mg of nitrate per litre for drinking water. Yet our bodies generate 50mg by natural processes every day, and the average person takes in 75mg from food. There is a lot of nitrate in vegetables, especially lettuce, spinach, carrots and beetroot.

In the past, a small number of babies received an excess of nitrate when women on remote farms used well-water to make up their feed. The water contained 500mg of nitrate per litre, and they also had bacteria which made even more nitrate in the body. The result was blue-baby syndrome and sometimes a baby died. The last such death in Britain was 40 years ago.

Then there are the dioxins. These natural chemicals form whenever anything burns: a bonfire of leaves, petrol in a car engine, or a joss stick. There are 210 dioxins, of which 17 are toxic. The dangerous ones cause acute acne in humans, but whether they cause cancer is doubtful. Thousands around Seveso in Italy were exposed to the dangerous dioxins in 1976 after an industrial accident. Last year their medical records were analysed by Pier Alberto Bertazzi, of the Institute of Occupational Health at Milan University. He found no rise in the total number of cancers.

And a final thought. Lard is mainly an unsaturated fat - like human body-fat, it consists of about 60 per cent unsaturated and only 40 per cent saturated. About two-thirds of the fat in butter, on the other hand, is saturated. But there is no simple division of animal fats being bad for you and vegetable fats good: coconut oil contains 92 per cent saturated fat. Something for the chemically- challenged to remember the next time they open a box of chocolates for a coconut fancy.

John Emsley's book 'The Consumer's Good Chemical Guide' has just been published by W H Freeman, pounds 18.99.

(Photographs omitted)