There has been a dramatic increase in the use of chemicals in recent years, many of them new compounds and mixtures whose toxicological properties have not previously been studied and which might prove to be harmful to humans. Over the last fifty years several substances previously thought to be inert or harmless in humans have been found to be carcinogenic (e.g. asbestos minerals) or toxic to the reproductive process (e.g. thalidomide). A wide and increasing range of compounds have been shown to be mutagenic or carcinogenic in animal studies. Consequently, in spite of our limited knowledge of the hazards to humans associated with many substances, most governments in the developed world, as part of their function to protect their populations, have developed legislation aimed at protecting both the working and the general population. This has usually required the management of enterprises to eliminate or at least to minimise any risks associated with their work both to their workers and to the general population.