The Relationship Between the Dust Lead Concentration and the Particle Sizes of Household Dusts Collected in Jersey City Residences

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Abstract
Lead concentrations measured in total dust samples collected from various environmental surfaces have been used as a surrogate for the lead concentration found in hand dust and subsequently in calculations of lead exposure due to ingestion. However, since the relationship between the characteristics of environmental dust samples and hand dusts is not yet well established, conclusions derived from lead measurements in contaminated household dusts may provide misleading information about childhood exposure. Household dusts collected from seven different residences by a high efficiency particulate air vacuum cleaner were sieved into eight different size fractions (>500, 500 to 355, 355 to 250, 250 to 180,180 to 125, 125 to 90, 90 to 63, and <63 μm) and analyzed for lead in dust (PbD) concentrations using both flame atomic absorption and laboratory X-ray fluorescence. In contrast to results found for street dust, where the PbD concentration increased as the particle size decreased, the reported results indicate that PbD concentration in household dust for six of the seven residences increased as particle size increased. The PbD concentrations in the fractionated dusts ranged between 700 ppm (dust 500 μm in diameter). Analyses suggested that the dust samples collected from residential environments will have a location-specific distribution of lead concentration that is a function of particle size. The results show that the lead mass and dust mass distributions differed substantially among the seven households as a function of particle size, possibly reflecting different local lead sources, different weathering processes, and different household activities which determine the particle size distribution. For each of these seven Jersey City, New Jersey, household dusts, total PbD concentrations (ppm) were higher than the PbD concentrations (ppm) for particles <125 μm. Leaded paint was the main source of lead-rich particles in the household dusts analyzed in this study. Strong correlations were observed between particle size and concentrations of the elements lead, titanium, and barium in fractionated dust samples known to be rich in leaded paint dust. With the current knowledge suggesting that dust particles which adhere to dry hand surfaces are primarily smaller than 10 μm, this study suggests that there is a potential for overestimating children's blood lead levels by using total PbD concentration as the surrogate for hand dust PbD concentration.