1997 WHRG Grant Program

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Geographic Pathology of Congenital Heart Defects
Christopher A. Loffredo, Ph.D.
School of Medicine, University of Maryland, Baltimore

Recent case-control studies of mothers of infants with birth defects, including the Baltimore- Washington Infant Study of congenital heart defects in our own region (Ferencz, et al. 1993, 1997), have interviewed women about their personal exposures to xenobiotics during pregnancy, in order to test or generate hypotheses about possible environmental risk factors for birth defects. The question of ecologic, or area, exposures has not been systematically addressed in such studies, so the contribution of these additional environmental exposures to birth defect risk is largely unknown. The recent development of geographic information systems (GIS) software makes it possible to conduct fine-scale geographic mapping of the distribution of birth defects, which can be used in combination with environmental maps to look for clustering of cases and possible relationships to pollution sources and other ecological hazards. The proposed research will apply the latest GIS technology to the extensive epidemiologic database of the Baltimore- Washington Infant Study, which includes detailed address information already collected and coded on self-reported maternal residence at the time of conception and workplace address during pregnancy. Using maps produced by GIS at the level of zip code and census block group, the study will test the hypotheses about the geographic distribution of residences and workplaces of mothers of infants with congenital heart defects, in comparison to mothers of randomly selected, population-based control infants who are free from birth defects. The demonstration of any significant case-control differences in these residence and workplace distributions may suggest possible differences in ecologic exposures of mothers during their pregnancies. The study will also be able to detect any possible geographic clusters of cases, which has not been previously attempted at the level of zip codes and census block groups. Furthermore, the locations of major industrial point sources of air and water pollution, available from the national Toxic Release Inventory database, will be plotted and compared to the distributions of residences and workplaces of cases and controls, and comparisons will be made according to distance and intensity of environmental pollutants. The study will establish the feasibility of geographic mapping of congenital heart defects in this region, as well as the feasibility of linking the personal address data with industrial emissions data. If successful, the project will lead to applications for extramural funds to extend this methodology to other birth defects and other environmental databases.