Comparison of Two Techniques for House Dust Lead Source Apportionment. J. L. Adgate, G. G. Rhoads, and P. J. Lioy, Environmental and Occupational Health Sciences Institute, Box 1179, 681 Frelinghuysen Road, Piscataway, New Jersey, 08855-1179
Ingestion of house dust is a major pathway for lead exposure in up to 6 million preschool children in the United States. This paper assesses the relative contribution of interior and exterior source pathways that contribute lead to house dust. Dust wipe and vacuum samples were collected in preschooler’s primary activity microenvironments as part of the Jersey City, New Jersey Childhood Lead Exposure Assessment and Reduction Study. Samples of lead-based paints, soils, street dusts, and local air pollution were obtained to examine the relationship between these proximal sources and lead in house dust. Lead isotope mixing equations were used to apportion the major contributors of lead mass in 22 wipe samples from interior window sills and bare floors. Quantitative estimates of the contribution from paint, soil, and street dust were obtained for ~70% of the samples. Lead-based paint contributed 0-55% of the lead mass in floor wipe samples and 45-100% of the lead mass in sill wipe samples. A chemical mass balance receptor model was used to apportion the major contributors of lead mass in 64 vacuum-collected dust samples. Coarse (30 m median diameter) house dust particle size fractions was analyzed by x-ray fluorescence for lead and 34 elements. A mass balance was calculated using source profiles that represented major contributors to house dust lead. Source profiles used were 1940s-1950s era lead-based paints, local air pollution, and a crustal profile representing the contribution of yard soils and street dusts. Crustal sources contributed an average of 49 24% of the lead mass to house dust, while lead-based paint and local air pollution contributed an average of 34 20% and 17 16%, respectively. The source apportionment techniques used in this study allows for quantification of relative contribution of these sources to lead in house dust. Implications for reducing lead exposure in pre-school children are discussed.
Work supported by the Centers for Disease Control under cooperative agreement U67/CCU210792-0 and the U.S. EPA under cooperative agreement CR820235.