Toxic chemicals are to us now what viruses were a century ago the hidden enemy and the source of much illness. In our everyday life we are now so immersed in chemicals at last count there were 70,000 of them out there that most of the latest syndrome

There is now sick building syndrome, wood preservative syndrome, solvent intolerance, chemically associated immune dysfunction, Gulf War syndrome, not to mention the more obtuse appellations like ecological disease, clinical ecology syndrome, chronic fatigue syndrome, fibromyalgia, and, our latest, multiple chemical sensitivity all hinting at an environmental cause.

Despite increasing evidence that chemicals are making many people ill, the medical establishment stubbornly hangs on to microbes as the one and only only source of illness, considering any other problem the stuff of the sufferer's fevered imagination. This was the conclusion of the 1996 Royal College's Report on chronic fatigue syndrome and on MCS problems, Nevertheless, the editor of the Lancet, Dr Richard Horton, took a brave step forward by arguing: "Somehow I cannot accept that pesticides, sprays and gases are the harmless accoutrements of today's life. But how do we prove it one way or the other?"

Although some good scientific studies have already proved that some people are hypersensitive to chemicals (see main story this month), the crux of the problem is really finding out exactly how these chemicals damage us which of our chemical pathways they disturb.

There is no way to determine, for instance, if a single chemical disrupts hormones, say, simply by examining its molecular make up. You have to subject it to a battery of tests, which, incidentally, have yet to be devised. Just consider, for a moment, the prospect of testing 70,000 chemicals, one by one.

An even more mountainous problem concerns the effect of these substances in tandem. We now know that the combined effect of two or three pesticides at low levels as might be found in most ordinary modern environments magnifies by up to 1600 times the effect of any insecticide by itself. So that means it makes sense to test these chemicals in combination. But as Rachel's Environment & Health Weekly pointed out (13 June, 1996): "To test just the commonest 1000 toxic chemicals in unique combinations of three would require at least 166 million different experiments (and this disregards the need to study varying doses).

"Even if each experiment took just one hour to complete and 100 laboratories worked round the clock seven days a week, testing all possible unique three-way combinations of 1000 chemicals would still take over 180 years to complete."

That staggering notion requires all of us to shout a little louder at the chemical industry. At the moment, most chemicals are innocent until proven guilty.

Consumers must demand that far fewer chemicals be used, and only those about which most is known; that pesticides be employed only for emergencies; and that manufacturers have the burden of proof, to prove a chemical is safe before it can be circulated.

Perhaps most important, we must no longer allow the deadly triad of the medical, pharmaceutical and chemical giants to pretend that the beginnings of an environmental plague are all in our heads, a pretense that allows them to get away with murder.

!ALynne McTaggart