50 years ago in JRSM

Abstract

This article was first published by JRSM in Volume 58 issue 5, May 1965. Our full back archive is available online at jrs.sagepub.com. Among the objects of this newly founded Section of Occupational Medicine are: first, 'to provide a means, not readily afforded elsewhere, whereby physicians and surgeons with a special knowledge of the rela-tionship between sickness and injury and conditions of work may discuss their problems, not only with each other, but also with colleagues in other fields, by holding joint meetings with other Sections of the Society'; and second, 'to make available information about the physical, chemical and psychological haz-ards of occupation, and in particular about those that are rare or not easily recognized'. At this first meeting of the Section and before, with however laudable intentions, we set about instructing our colleagues in other fields, it will be proper to con-sider a problem fundamental to our own. How in the first place do we detect these relationships between sickness, injury and conditions of work? How do we determine what are physical, chemical and psy-chological hazards of occupation, and in particular those that are rare and not easily recognised? There are, of course, instances in which we can reasonably answer these questions from the general body of medical knowledge. A particular, and per-haps extreme, physical environment cannot fail to be harmful; a particular chemical is known to be toxic to man and therefore suspect on the factory floor. Sometimes, alternatively, we may be able to consider what might a particular environment do to man, and then see whether such consequences are indeed to be found. But more often than not we have no such guidance, no such means of proceeding; more often than not we are dependent upon our observation and enumeration of defined events for which we then seek antecedents. In other words, we see that the event B is associated with the environ-mental feature A, that, to take a specific example, some form of respiratory illness is associated with a dust in the environment. In what circumstances can we pass from this observed association to a verdict of causation? Upon what basis should we proceed to do so? I have no wish, nor the skill, to embark upon a philosophical discussion of the meaning of 'caus-ation'. The 'cause' of illness may be immediate and direct, it may be remote and indirect underlying the observed association. But with the aims of occupa-tional, and almost synonymously preventive, medi-cine in mind, the decisive question is whether the frequency of the undesirable event B will be influ-enced by a change in the environmental feature A. How such a change exerts that influence may call for a great deal of research. However, before dedu-cing 'causation' and taking action, we shall not invariably have to sit around awaiting the results of that research. The whole chain may have to be unra-velled or a few links may suffice. It will depend upon circumstances. Disregarding then any such problem in semantics we have this situation. Our observations reveal an association between two variables, perfectly clear-cut and beyond what we would care to attribute to the play of chance. What aspects of that association should we especially consider before deciding that the most likely interpretation of it is causation?