Epidemiology is the study and investigation of the distribution and causes of disease. Evaluations of distributions of a disease may include the investigation of geographical distributions, and in toxic tort personal injury claims, where epidemiological studies are important and necessary, the studies are used to evaluate whether exposures to specific chemicals or products are risk factors for the development of the disease. Epidemiology does not establish causation per se between an individual’s exposure and their disease, but the discipline helps in identifying and understanding risk factors that may have an inference of association with the disease.
There are a variety of different epidemiological study designs. Some studies follow people through time, evaluating those exposed to a risk factor and comparing them for disease outcome with similarly matched people who are not exposed. Other study designs look at populations of people at a point in time, and evaluating the disease outcome. Retrospective study designs go back in time and follow persons exposed in a particular activity to evaluate patterns and disease outcome. Regardless of the particular study design, epidemiological studies are important for identifying, evaluating and understanding risk factors that may be associated with a disease.
Trial Courts around the country are utilizing, and often times requiring, the use of epidemiological studies in toxic tort personal injury claims to help in the determination of a person’s exposure to a particular chemical, agent, or product, and the disease being alleged to have resulted from the exposure. In Texas, the 1997 Texas Supreme Court ruling in Merrill Dow Pharmaceuticals, Inc. v. Havner adopts and embraces the use of epidemiological studies in toxic tort claims. However, many epidemiological studies can be flawed and require careful execution and scrutiny if they are to be credible.
To be successful in toxic tort litigation, and any litigation where epidemiology is essential to help understand issues of causation, an understanding of the integration of science and law is essential between legal issues and the scientific issues of epidemiology and associated scientific disciplines.
The discipline of epidemiology also embraces the areas of Industrial Hygiene, Toxicology, Exposure/Risk Assessment, and Ecology. Industrial Hygiene helps to identify, evaluate, and control workplace exposures to a variety of chemicals and agents. Toxicology aids in the evaluation of the dose of exposure and the response from each dose, largely relying on animal studies. Exposure and risk assessments are necessary to quantify the exposure, and help in the development of strategies to reduce exposures. The exposure either via soil or ground water often is characterized through geological and hydrogeological investigations, associated environmental investigations, microbiological studies and laboratory analyses. These ecological studies help in the evaluation and understanding of the environmental impact as a result of exposures, whether to water, soils, humans or other animals in the environment. In toxic tort and environmental litigation, the integration of all these scientific disciplines, in conjunction with epidemiology, is necessary for a comprehensive picture and understanding of the scientific and legal issues involved.
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The I2M Associate and Principal responsible for this discipline’s activities are:
F. Ben Thomas, Ph.D. (Semi-Retired)