United States house dust Pb concentrations are influenced by soil, paint, and house age: insights from a national survey

Abstract

Background Lead (Pb) in house dust contributes significantly to blood lead levels (BLLs) in children which may result in dire health consequences. Assessment of house dust Pb in the United States, relationships with Pb in soil and paint, and residential factors influencing Pb concentrations are essential to probing drivers of house dust Pb exposure. Objective Pb concentrations in vacuum-collected house dust are characterized across 346 homes participating in the American Health Homes Survey II (AHHS II), a US survey (2018–2019) evaluating residential Pb hazards. Connections between house dust Pb and soil Pb, paint Pb, and other residential factors are evaluated, and dust Pb concentration data are compared to paired loading data to understand Pb hazard standard implications. Results Mean and median vacuum dust Pb concentrations were 124 µg Pb g−1 and 34 µg Pb g−1, respectively. Vacuum-collected dust concentrations and dust wipe Pb loading rates were significantly correlated within homes (α < 0.001; r ≥ 0.4). At least one wipe sample exceeded current house dust Pb loading hazard standards (10 µg ft−2 or 100 µg Pb ft−2 for floors and windowsills, respectively) in 75 of 346 homes (22%). House dust Pb concentrations were correlated with soil Pb (r = 0.64) and Pb paint (r = 0.57). Soil Pb and paint Pb were also correlated (r = 0.6). Impact The AHHS II provides a window into the current state of Pb in and around residences. We evaluated the relationship between house dust Pb concentrations and two common residential Pb sources: soil and Pb-based paint. Here, we identify relationships between Pb concentrations from vacuum-collected dust and paired Pb wipe loading data, enabling dust Pb concentrations to be evaluated in the context of hazard standards. This relationship, along with direct ties to Pb in soil and interior/exterior paint, provides a comprehensive assessment of dust Pb for US homes, crucial for formulating effective strategies to mitigate Pb exposure risks in households.

Lead Speciation, Bioaccessibility, and Sources for a Contaminated Subset of House Dust and Soils Collected from Similar United States Residences

“…9,27,28 Although similar, unique Pb species found in the Health Canada house dust investigations may be due to a focus in those studies of homes located in urban locations near industry, increasing likelihood of industrial Pb source translocation into house dust. 2,8,51,52 Pb contamination in house dust has decreased with time in the United States, and newer homes tend to have lower dust Pb concentrations, 34 contributing to an overall decrease in mean BLLs since the banning of Pb-based products. 53,54 However, homes where Pb contamination is already present are facing similar risks to what was observed 15 years ago.…”

“…7 Disparate house dust and soil Pb sources were unexpected given that Pb concentrations were previously found to be related for the overall AHHS II study (r = 0.64). 34 Similarities in Pb concentrations but differences in sourcing suggest that either Pb phases are changing over time or residences where Pb contamination is present is likely to manifest in multiple residential matrices, regardless of specific Pb phases. XRF results from exterior residential surfaces confirm that Pb-based paint remains present on exterior surfaces for a majority of the homes evaluated (at least seven of eight homes), providing evidence that phases indicative of Pb-based paint may be degrading, since Pb (hydroxy)carbonates were not observed in soils.…”

“…Although BLLs have decreased with time, there remain areas of high Pb contamination, especially in urban areas, throughout the US where our understanding of Pb bioaccessibility and sourcing is limited. The overarching AHHS II study found United States house dust, soil, and paint Pb concentrations to be correlative; 34 however, advanced characterization data was needed to determine geochemical connections between these pools and to identify predominant Pb species in residences with elevated contamination. Using a AHHS II subset of residentially paired house dust and soils possessing elevated Pb contamination (>300 μg Pb g −1 ), we showcase mineral phases associated with Pb-based paint (i.e., Pb (hydroxy)carbonate)) continue to dominate the Pb chemistry of contaminated house dust, subsequently driving elevated (>60%) Pb bioaccessibility.…”

“…35 Further detail on AHHS II, sample collection, and dust/soil processing may be found in the SI and previous EPA-HUD reports. 5,34 Each unique sample was digested in duplicate in trace metal grade aqua regia (3:1 HCl: HNO 3 ). Digestions were performed in a heated graphite block with a hold-time of 30 min at 60 °C followed by a hold-time of 45 min at 95 °C.…”

“…5,33 We have recently reported total Pb concentrations and correlations for house dust, soil, and interior/exterior paint, where we found total Pb concentrations in house dust (mean: 124 μg Pb g −1 ) to be correlative with soil (mean: 135 μg Pb g −1 ) and paint (mean: 135 mg Pb cm −2 ) for 295 residences. 34 The AHHS II study provides important insights into residential Pb relationships from a Pb concentration basis; however, there remains a need to probe Pb phases, sources, environmental stability, and bioaccessibility for house dust and soil samples known to contain elevated concentrations of Pb. Here, we selected an elevated Pb concentration (>300 μg g −1 ) subset of AHHS II house dust and soil pairs to (1) investigate house dust and residential soil Pb species, (2) connect Pb phases to bioaccessibility results to assess potential exposure, and (3) identify potential associations between house dust and residential soil Pb.…”