Targeting peri-conceptional exposure assessment using regulatory water quality databases

Environmental exposures may be important to conception and fetal development, but testing and quantifying exposure for each participant in a large population-based study would be very costly. Water quality data are routinely collected for regulatory purposes, but determining which water system serves a certain address is often difficult. Further, water quality levels can vary within a distribution system. We developed a method for estimating exposures to contaminants in finished drinking water by combining water use data, collected directly from study participants, with water quality data from public water supplies. Women trying to conceive reported usual sources and amount of drinking water at baseline and then at their fertile peak, determined by monitoring fertility signs, during each menstrual cycle. We first linked the water quality testing results from state and federal databases to GIS layer delineating the areas served by that water supply. We then used a GIS to link each participant's address to the water system that served them, and the quality of water delivered by that system. Exposure estimates were generated by combining the water quality levels with the consumption patterns. This method of exposure assessment using administrative data allows for estimating women's exposure to analytes that might potentially affect conception or continuation of pregnancy without expensive water collection and analysis. Collecting both baseline and cycle-based water consumption data allows for generation of chronic and transient exposure estimates. We have applied this exposure assessment method to several other existing cohorts and thereby generated population-based distributions of potential exposure.