Using GIS for Exposure Assessment of Disinfection By-Products in the Six State National Birth Defects Prevention Study

In 1998, EPA-CDC Interagency Agreement #DW7593021-01-0CDC (IAG) was supplemented to further evaluate the potential association between birth defects and disinfection byproducts (DBPs). One of the primary activities of this agreement was to add a tap water use and consumption component to the National Birth Defects Prevention Study (NBDPS) interview. This task was accomplished, in part, through a contract with Battelle, which included a subcontract to Colorado State University (J.R. Nuckols, PI).

The NBDPS is a study of birth defects being conducted by the Centers for Birth Defects Research and Prevention (CBDRP). Each year, approximately 2,400 case-infants and 800 control-infants are enrolled in the NBDPS (300 case infants and 100 control infants from each CBDRP). Detailed information is obtained through maternal interview on numerous established and potential birth defects risk factors. CDC/EPA interagency funds were used to design, pilot, and integrate questions on tap water use and consumption into the hour-long NBDPS computer assisted telephone interview (CATI). Questions were included on drinking water consumption (at home and at work), home water use, bathing habits, and other information relevant to potential exposure to DBPs (both trihalomethanes and haloacetic acids). In September 1999, the drinking water module was piloted in the Atlanta and New York NBDPS sites. In February 2000, questions on tap water use and consumption were incorporated into the main NBDPS CATI. The tap water component is now administered to all NBDPS participants.

In addition to supporting the development of the tap water module, a portion of the CDC/EPA IAG funds supported the technical assistance of Dr. Nuckols, who constructed a geographic database in Access(r) for each geographic region served by the NBDPS. These data were obtained from the USEPA Safe Drinking Water Information System (SDWIS), USEPA Information Collection Rule (ICR) database, and the state agencies with regulatory responsibility for drinking water quality. The geographic database includes utility monitoring data from approximately 6,200 utilities and more than 95,000 water samples analyzed between the years 1995-1999. Dr. Nuckols also developed analytic methods to rank utilities by the degree of spatial variance in their DBP concentrations. Data obtained from the State of Texas were recently used as a pilot for developing an exposure classification metric for DBPs (trihalomethanes and haloacetic acids) among NBDPS study participants living in Texas. The Texas pilot study was conducted in collaboration with the Texas Department of Health (P. Langlois, PI) and the Centers for Disease Control and Prevention (M. Lynberg, PI) under an American Water Works Association Research Foundation grant (AWWARF Project 2832, Linking Geographic Water Utility Data with Study Participant Residences from the National Birth Defects Prevention Study (AWWARF, CDC). Results from the Texas pilot study are being used as a basis for the exposure classification methods in this current project.

The goal of the current study is to determine the extent to which utility water quality monitoring data on THMs and HAAs can be linked with residential information of NBDPS participants in six geographic areas covered by the NBDPS. By this project, we will use the methods developed in the Texas Prototype study to link these data to the NBDPS Tap Water exposure component.

Ultimately, we aim to: (1) provide technical assistance to Battelle and the CDC in the use of an existing geographic water utility database; (2) maintain, edit, analyze, and manage the geographic water utility database for use in exposure assessment studies of disinfection byproducts. Including the collection of additional water utility data, as needed for linkage; (3) assist in the linkage of tap water information from the geographic database with residence information and water use data obtained from health study interviews; and, (4) assist in the estimation and classification of exposure based on reported water use and tap water characteristics, to the extent feasible.