Rational inquirers

Rarely does a day go by without the press reporting some scare about a noxious agent or a perceived biological threat. We are rightly concerned about infection, be it by viruses, bacteria or fungi; we fear the consequences of a polluted environment; we need, but are uneasy about, nuclear power; we do not know the causes of Gulf war syndrome. In the search for answers, comforting or not, we rely on the power of analytical science. Take, for example, the problem of bovine spongiform encephalopathy and its relation to Creuztfeldt-Jakob Disease. How does one determine the causes of BSE and CJD? How does one find, and quantify, the causative agent? Are these diseases associated with the presence of prions or is some more conventional agent the cause? If BSE is associated with prions, what is there about their structure or behaviour that leads to the dreadful consequences?

In answering these questions, analytical science will play its part, whether it be in the analysis of the proteins or the DNA, in crystallographic or magnetic methods of structure determination and in isotopic or fluorescence methods of location. Or, to take a more conventional threat: one might imagine that living species have defences against most toxins but that defence will be dependent on the chemical and physical state of the toxin, the other components in the sample, the method of exposure or ingestion. For example, everyone knows that mercury is "harmful" - but in what form? Exposure to liquid mercury is less harmful than breathing the vapour, especially of clean mercury, since the equilibrium is much influenced by dirt or contaminants on the surface of the liquid. However, both are much less harmful that the methylated form of mercury that is a potent neurotoxin. This was the cause of the Minamata disaster, where the combination of a derivative of Vitamin B12, present in the bacteria that existed in sewage sludge, reacted with a discharge from a neighbouring factory to give the noxious compound that survived all the way up the food chain until it was ingested by some local villagers with disastrous consequences.

Will we ever be able to say with confidence that a certain amount of a toxin is "safe"? Safe for whom? Advances in analytical science have meant that our ability to detect and analyse many pollutants has improved remarkably due to methods expertly described in this comprehensive encyclopedia, to such an extent that it is within the power of scientists to isolate and characterise single molecules. But, if we find that a sample contains, say, one molecule of dioxin, one atom of plutonium, or an Ebola virus, etc, is that too much? Have we no defence mechanism against the ravages of these entities? Though we have, presumably, defences, albeit inadequate, against viruses, do they exist against dioxin or plutonium? Even simple toxins like ethyl alcohol have limits that depend on the age, sex, or race of the person exposed to them.

Say the problems result from the defence: it is quite commonly believed that some reasonably innocent materials as, in, say, tobacco smoke, are converted into harmful substances by the defence array present in ourselves. But we are marked by a high degree of variability within the population. The same compound, in the same form, can either go unnoticed or induce fatalities. We are all different and therein lies the strength of most living things but also subsumes its weakness. How do we defend ourselves against this, usually unseen, threat? The most obvious answer is to "spread the risk", particularly when we are not sure or aware of the danger. If one restricts oneself to a limited diet, then one increases the risk: the chances are that someone who had a varied exposure might be safer in the long run. Everyone knows about the unfortunate circumstances that lead to many people being exposed to materials that induce a violent allergic response. In the last analysis, these are often due to a simple chemical or biochemical reaction that triggers off a dramatic reaction.

The purpose of all scientific endeavour is to acquire information, test and construct theories that allow a coherent explanation of widely diverse phenomena. The Encyclopedia of Analytical Science is concerned with the objects we wish to study and the methods by which we do so. It will be extremely valuable to all concerned with the prosecution of most aspects of experimental science. It addresses not only the objects of investigation, but, to a large extent, the methods and techniques that are used to determine how much there is of a given material and what form it is in. Never before have so many different techniques been described in so exemplary a fashion, be they of recent origin, as in scanning tunnelling microscopy or the myriad developments of magnetic resonance spectroscopy or of more obvious applicability such as mass spectrometry or gas chromatography.

What distinguishes this collection from those that have gone before is that it is not restricted to purely chemical means or topics. Thus immuno-assays are well described, as are the uses of enzymatic methods. However, the most useful aspect to the general inquirer is the way these methods are juxtaposed with articles that illustrate the many and varied recipients of the attention from these methods. These include the use in forensic science, drug screening in sport, food and nutritional analyses and effluent analyses.

I was somewhat concerned about the articles on sensors since they did not convey the excitement of the subject. In addition, some chapters appeared rather out of date. But it is hard to imagine any science library not having these volumes available. It is an extremely valuable publication, even though some chapters are of questionable standard and there are many unhelpful or superfluous figures. (The last is more than compensated for by some beautiful photographs.) Most of the chapters are excellent, however, and the editor and his associates deserve our thanks.

H. A. O. Hill is professor ofbioinorganic chemistry, University of Oxford.