ABSTRACT

The study of trace elements reminds us of the essential coherence of these diverse realms, linked as they are by the economy of design and purpose so conspicuous in the Creator’s strategy. Because the trace elements constitute a scarce resource, they have to fill many roles—-toxic, beneficial, essential, fortuitous—which sometimes appear to conflict or to overlap. Methyl mercury is potentially toxic but is sufficiently diluted in the sea to be harmless to fish—and, in general, to people who eat fish which has not been exposed to additional man-made sources. In these ways potentially toxic trace elements are kept on the move, preventing an unwelcome build-up in sensitive places, and the limited supply of some essential elements is continually recycled. Among the chemical elements some are abundant and versatile, appearing in a wide range of compounds and some are scarce and highly specialised.