Grand Rounds: Epidemiological methodology, law and environmental health
Objective: To define a new approach to causality determination
Methods: Two distinct research situations are defined: (a) determining a causal connection between past exposure to an established risk factor and an outcome (such as a known carcinogens) in a sick individual, an approach often required in tort litigation, and usually based on published scientific reports; and (b) discovering a new causal connection between an exposure (e.g., an exposure to a substance that is not known as a carcinogen) and an outcome (e.g., occurrence of cancer) in a population, an approach that is appropriate in scientific research. Results and conclusion: Determining causality after exposure of an individual to a known carcinogen requires a retrospective approach, and causality is determined exclusively by a priori knowledge of carcinogenicity and proof of exposure. Conversely, discovering a new causal risk factor requires a forward-directed reasoning and a population approach based on Hills criteria.
Shai Linn is the Dean of the Faculty of Social Welfare and Health Sciences at the University of Haifa, and Director of the Unit of Clinical Epidemiology at Rambam Health Care Campus. After graduating from the Faculty of Medicine at the Hebrew University in Jerusalem, he received Master of Public Health (MPH, 1979) and Doctor of Public Health (Dr.P.H., 1981) degrees from Harvard School of Public Health. He was then appointed as a Deputy Director of the Rambam Hospital (1982-1985). This was followed by a fellowship at the U.S. National Institutes of Health in 1985-1986 and selection as Fellow of the American College of Epidemiology. In 1990-1992 Dr. Linn received the prestigious MacArthur – SSRC Fellowship, and was appointed as a Visiting Professor of Epidemiology at the Department of Health Care and Epidemiology of the University of British Columbia, Vancouver, BC.
Dr. Linn's main research interests are epidemiological methodology and environmental health.
Key words: Causality, Directionality, Environment, Epidemiology, Methodology, Study Design, Timing