This effort was based on several completed or existing projects where disinfection by-products ( or DBPs) have been the primary exposure of interest. Previous epidemiologic results on reproductive or developmental risks that may be associated with consumption of disinfected drinking water are considered equivocal for many reasons. Some of the between-study differences may be due to unmeasured differences in the type and occurrence levels of mixtures of DBPs and other water exposures. These differences may also be due to incomplete assessment of all likely routes of exposure to humans and reliance on aggregate measures to estimate individual-level exposures. The integration of individual-level data will decrease these exposure uncertainties, aid decision makers in interpreting the results of both epidemiologic and toxicologic studies of waterborne chemical exposures, and will also further develop the scientific approaches for aggregate exposure assessment.

Exposure assessment limitations in environmental epidemiology is a major scientific issue with implications for public health policy. This project will integrate individual-level questionnaire-based information from epidemiologic study settings for different routes of exposure to DBPs. Data on the within- and between-individual variability in water consumption and water-related activities will be used to develop maternal exposure metrics. A sensitivity analysis evaluating the amount of exposure misclassification due to the use of different exposure metrics will be conducted. These exposure metrics may also be used in the parent study to examine their impact on risk for adverse reproductive outcomes in humans.