Measurement and assessment of Pb exposure risk from indoor dust in Broken Hill Australia) homes

Background

In urban areas under the influence of industrial emissions, elevated levels of metal contaminants in soils are often observed to persist in household dust. While health risks associated with exposure to these contaminants are potentially higher in indoor environments than outdoors, previous research has nonetheless favored studies focusing on contamination in outdoor environments.

Aim

The following study examines the dust and soil of 62 residences in the Australian lead (Pb) mining town of Broken Hill to determine the sources and pathways through which metal contaminants are introduced to indoor environments.

Method

Indoor vacuum cleaner dust from a total of 62 households along with surface soils from corresponding front yard and roadside locations were analysed to obtain representative metal concentrations (mg/kg) for Pb, arsenic (As), chromium (Cr), copper (Cu), manganese (Mn) and zinc (Zn). Analysis of surface soils at front yard and roadside locations was undertaken in situ using Portable X-ray Fluorescence spectrometry (pXRF). Household dust was sieved to 250 μm and analysed using pXRF. A further 20 samples were selected for ICP-MS analysis to identify sources of Pb in Broken Hill households.

Results

Median concentrations (mg/kg) in yard soil/household dust were: Pb 291/534; As 13/34; Cr 38/81; Cu 29/106; Mn 743/964; and Zn 709/961. Moderate positive correlations were identified between front yard soil and household dust for metals associated with the Broken Hill ore body. Metal concentrations were influenced by proximity to designated mining areas for both soil and dust. Household dust samples analysed by for their Pb isotopic compositions returned ratios (²⁰⁸Pb/²⁰⁷Pb: 2.3303; ²⁰⁶Pb/²⁰⁷Pb: 1.0526) comparative to those of the Broken Hill ore body (²⁰⁸Pb/²⁰⁷Pb: 2.3120; ²⁰⁶Pb/²⁰⁷Pb: 1.0410).

Conclusion

Contaminated emissions from Broken Hill mining operations have a direct impact on metal concentrations in the soil and dust of Broken Hill. Links between metal concentrations in indoor and outdoor environments demonstrate transport pathways between these environments and constitute a pervasive risk to the health of the Broken Hill community.