Future problems requiring scientific consideration.

Abstract

Water is essential for life, a precept that should control all other considerations. Water and its toxicological safety represent a paradigm for much of what is happening in other areas of society in evolving perceptions of what is 'toxicity', what is 'risk' and what we wish to or are prepared to do about such 'risks' at what cost to ourselves and others. Water is an universal solvent and may contain a wide diversity of substances arising from sources and supply systems and modified by treatment and storage. The problems that are already present, and which are closely linked to others just beginning to be recognisable, arise from the growing sensitivity of analytical techniques showing exposure to novel or ever smaller amounts of known substances in water, how to recognize and evaluate their conventional and possibly new (i.e. previously unrealized) toxic actions, how to measure exposure to water as drunk and as in foods and drinks, in what way can safe exposure levels be set, and is it feasible to people to demonstrate that 'safety' has been achieved? Behind those lie the very real problems of deciding what is 'safety', what level of notional safety do we demand in our assessments, and how do we, the people, come to realise and accept the costs that we shall have to pay in demanding any given level of 'safety'? The latter includes deciding what is an appropriate level of safety for the community as a whole and any specially susceptible groups within it. These questions are deceptively simple to pose and tortuously difficult even to attempt to answer. But they are not all the future problems. Behind them lie the socio-political uncertainties of risk and its place in society-what real or perceived risks do we accept and why, and how in a democratic society are we, the people, to be informed about risks, how should we decide what to accept or reject, and how are we to balance our beliefs and wishes against the costs of prevention or acceptance of diseases that unclean or contaminated water can bring.