Bhopal Accidental Release: 1984 accident in Bhopal, INDIA at a PESTICIDES facility, resulting when WATER entered a storage tank containing ISOCYANATES. The following accidental chemical release and uncontrolled reaction resulted in several thousand deaths.Epidemiologic Methods: Research techniques that focus on study designs and data gathering methods in human and animal populations.Molecular Epidemiology: The application of molecular biology to the answering of epidemiological questions. The examination of patterns of changes in DNA to implicate particular carcinogens and the use of molecular markers to predict which individuals are at highest risk for a disease are common examples.Epidemiologic Studies: Studies designed to examine associations, commonly, hypothesized causal relations. They are usually concerned with identifying or measuring the effects of risk factors or exposures. The common types of analytic study are CASE-CONTROL STUDIES; COHORT STUDIES; and CROSS-SECTIONAL STUDIES.Epidemiologic Research Design: The form and structure of analytic studies in epidemiologic and clinical research.Epidemiology: Field of medicine concerned with the determination of causes, incidence, and characteristic behavior of disease outbreaks affecting human populations. It includes the interrelationships of host, agent, and environment as related to the distribution and control of disease.Risk Factors: An aspect of personal behavior or lifestyle, environmental exposure, or inborn or inherited characteristic, which, on the basis of epidemiologic evidence, is known to be associated with a health-related condition considered important to prevent.Epidemiologic Factors: Events, characteristics, or other definable entities that have the potential to bring about a change in a health condition or other defined outcome.