Evaluation of Four Sampling Methods for Determining Exposure of Children to Lead-Contaminated Household Dust

Abstract

Childhood exposure to lead has been demonstrated to result in health effects and lead-contaminated household dust is a primary exposure source. There is a need to establish reliable methods for sampling surfaces to determine levels of lead contamination. Three vacuums (HVS3, GS80, and MVM) and one wipe method were evaluated for the collection of household floor dust under field sampling conditions within a Superfund site and demographically similar control area. Side-by-side floor samples were taken from three locations within 41 randomly selected households between August and September 1995: a child's bedroom, primary play area, and primary entrance. Analysis was performed to assess the relative collection performance of each sampler, spatial distribution of lead within a household, and correlation of lead loading with observed blood lead level, and to determine if discrete or composites samples were more predictive of blood lead levels. Approximately 90% of the floor surfaces were carpeted. The rank order of sampling methods from greatest to lowest collection efficiency was HVS3 > GS80 > wipe > MVM. The HVS3 had the highest level of precision (CV=0.05), with the GS80 and wipe precisions 0.48 and 0.053, respectively. Lead loadings for samples collected in bedrooms and living areas and composite samples using the HVS3 and wipe methods were significantly correlated with blood lead levels. Correlations between blood lead levels and composite samples were stronger for the HVS3 (R2=0.33, P=0.003) and wipe (R2=0.25, P=0.002) methods than the respective discrete samples. Regression analysis indicated that a blood lead level of 10 μg/dl corresponds to a carpet wipe sample geometric mean of 68 μg/ft2. For ongoing public health purposes, such as screening and clearance testing, use of the wipe sampling method is the most appropriate. This investigation supports findings by others that the present HUD risk levels for lead in floor wipe samples may not be adequate for reducing children's blood lead levels below 10 μg/dl.