Symposium on Target Organ Toxicity: cardiovascular system. The epidemiologic approach.

Epidemiological studies rarely provide unequivocal data on the effects of toxic substances on human health. Unlike experimental studies, pertinent variables frequently cannot be controlled and some are often unknown. Nevertheless, these limitations can be dealt with by various facets of an epidemiological investigation. These include, the choice of a study design, selection of controls or comparison populations, evaluation of available data, statistical analysis, and the drawing of appropriate inferences from the data. Among the special problems that might be encountered in studies of the effects of cardiotoxic substances are, difficulties in establishing diagnoses, errors in death certificates, observer errors in electrocardiographic interpretations, and taking into account the effects of various risk factors known to be implicated in the etiology of cardiovascular diseases. In spite of various methodological problems and certain inherent limitations of epidemiological studies, they can, when properly conducted, make significant contributions to knowledge of disease etiology and provide the means of reducing the risk of a disease, even when its etiology is not completely known.