Given the ethical limitations of human testing, most non-drug-related epidemiology studies rely on observational data rather than clinical studies that estimates existing chemical exposures and disease prevalence. “Cohort studies” are a type of observational study that follows a group of people known as a “cohort” over a number of years, measuring their exposures to chemicals found in their environment (rather than administering chemicals) and assessing the health of each study participant. By tracking a population over years, often decades, researchers examine whether highly exposed individuals are more likely to develop health ailments. Because cohort studies track exposure starting at the present and into the future, these studies are also classified as prospective studies.
Many complications arise in drawing conclusions from these studies, because of confounding factors. In addition, estimating exposure to chemicals requires interviewing study participants who may express their own biases or may not recall the facts accurately.
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