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Mortality statistics and the assessment of risk

For nearly 150 years, mortality statistics have provided the base that epidemiologists have used to quantify and evaluate risk. In early years these derived directly from information recorded on death certificates, which enabled medical statisticians to calculate periodically death rates for various causes of death by sex, age, area of residence and occupation. With time, interest moved from the immediate effects of an occupation to more delayed effects. Mainly as a response to this interest, the last 30 years have seen developments in national record systems that allow epidemiologists to mount prospective mortality studies capable of answering detailed questions about the nature of occupational risks and describing dose—response relations. This paper outlines these developments, thereby providing a background for the following paper, which describes the use of these methods in occupational studies of dose-response relations.