[Ethical aspects of intervention studies (author's transl)]

Since the Second World War international ethical codes have been developed which aim to protect the individual in relation to medical experimentation. It is in these codes, rather than in the provisions of different national codes, that the principles applicable to epidemiological intervention studies should be sought. Having recalled the main characteristics of such studies, and particularly those which distinguish them from clinical trials, the authors consider two specific aspects of the issue: the balance between risks and benefits, and informed consent. Concerning the risk/benefit relationship, it appears important to distinguish between primary prevention (the subjects involved are healthy but at risk), secondary prevention (the subjects involved have the disease in question but are asymptomatic) and tertiary prevention (the subjects involved are ill). The principles of informed consent in intervention studies may be drawn from those governing clinical trials, particularly where the intervention can be applied to individuals. When it cannot be individualized (for example, fluoridation of drinking water) the alternative suggested by some authors is that individual consent may be replaced by community consent or that of its representatives. Some implications of the observation of these two types of principles are considered.