High Lead Bioavailability of Indoor Dust Contaminated with Paint Lead Species

Abstract

House dust and soils can be major sources of lead (Pb) exposure for children. The American Healthy Homes Survey (AHHS) was developed to estimate Pb exposure from house dust and soil, in addition to other potential household contaminants and allergens. We have combined X-ray absorption spectroscopic (XAS) fingerprinting and in vivo mouse relative bioavailability (RBA) measurements for a subset of house dust and residential soils collected in the AHHS, with the primary objective of gaining a better understanding of determinants of house dust Pb bioavailability. Lead speciation was well related to variations in RBA results and revealed that highly bioavailable Pb (hydroxy)carbonate (indicative of Pb-based paint) was the major Pb species present in house dusts. Measured Pb RBA was up to 100% and is likely driven by paint Pb. To our knowledge, this is the first report of in vivo Pb RBA for U.S. house dust contaminated in situ with paint Pb and corroborates results from a previous study that demonstrated high RBA of paint Pb added to soil. We also report a relatively low RBA (23%) in a residential soil where the major Pb species was found to be plumbojarosite, consistent with a previous report that plumbojarosite lowers Pb RBA in soils.

Figure 1.

Pb X-ray absorption near-edge spectroscopic data (solid lines) and linear combination fits (dashed lines) for standard reference materials along with standards used in final fits (SRM 2581 & 2586). Fit statistics and spectroscopic standard contributions may be found in Table 2.

Figure 2.

Lead phase identification results from linear combination fitting analysis for A) paired house dust and residential soil samples and B) all house dust samples. First-derivative X-ray absorption near-edge spectroscopic data with overlaid fits are presented in SI Figure S2. Table 2 contains quantitative LCF results. SRM 2581 and SRM 2586 are Pb reference materials consisting of powdered paint and soil mixed with lead paint, respectively.

Figure 3.

Comparison of RBAs estimated from the regression slope ratio and bone-dose ratio. Points are mean RBA (n=16); error flags are SE. The solid line is the weighted linear regression model (see SI for details); dotted lines are the 95% confidence limits for the model. The regression model parameters are as follows: intercept: −0.01 ± 0.5 (SE); slope: 0.98± 0.10 (SE); r²: 0.87.

Figure 4.

RBA estimated for standard reference materials (SRMs), and paired house dust (D) and residential soils (S). Shown are mean RBA and 95% confidence limits.