International Analysis of Sources and Human Health Risk Associated with Trace Metal Contaminants in Residential Indoor Dust.

People spend increasing amounts of time at home, yet the indoor home environment remains understudied in terms of potential exposure to toxic trace metals. We evaluated trace metal (and metalloid) concentrations (As, Cu, Cr, Mn, Ni, Pb, and Zn) and health risks in indoor dust from homes from 35 countries, along with a suite of potentially contributory residential characteristics. The objective was to determine trace metal source inputs and home environment conditions associated with increasing exposure risk across a range of international communities. For all countries, enrichments compared to global crustal values were Zn > Pb > Cu > As > Cr > Ni; with the greatest health risk from Cr, followed by As > Pb > Mn > Cu > Ni > Zn. Three main indoor dust sources were identified, with a Pb-Zn-As factor related to legacy Pb sources, a Zn-Cu factor reflecting building materials, and a Mn factor indicative of natural soil sources. Increasing home age was associated with greater Pb and As concentrations (5.0 and 0.48 mg/kg per year of home age, respectively), as were peeling paint and garden access. Therefore, these factors form important considerations for the development of evidence-based management strategies to reduce potential risks posed by indoor house dust. Recent findings indicate neurocognitive effects from low concentrations of metal exposures; hence, an understanding of the home exposome is vital.

Atmospheric remobilization of natural and anthropogenic contaminants during wildfires.

Globally, wildfires are increasing in frequency and severity, exposing populations to toxic trace elements stored within forests. Trace element and Pb isotope compositions in aerosols (n = 87) from four major wildfires near Sydney, Australia (1994-2004) were evaluated (Mood's median test) to determine any significant differences in concentration before, during or after wildfires. The US EPA's positive matrix factorization (PMF) model was used to distinguish a wildfire-related particulate source factor. Atmospheric concentrations of Cd and Mn were approximately 2.5 times higher during fire periods. PMF modelling distinguished a soil factor (Ca, Si, Ti and Zn) and an anthropogenically-sourced factor (Cd, Pb). The Cd, Pb anthropogenic factor was present at twice the concentration during wildfire periods (compared to before or after). Lead isotopic analyses of aerosols revealed that former leaded gasoline depositions were subject to remobilization during post-2000 wildfire periods. Trace element increases during wildfires are unlikely to exceed health-based criteria.

Prevalence of childhood lead poisoning and respiratory disease associated with lead smelter emissions.

BACKGROUND: The city of Port Pirie in South Australia has been a world leading centre for lead and zinc smelting and processing since 1889 that continues to cause contamination of its environment and resident population. This study quantifies the effect of lead and SO2 emissions from Nyrstar Port Pirie Pty Ltd's smelter on blood lead and respiratory health outcomes, respectively, and establishes what air quality values are required to better protect human health. METHOD: Blood lead and emergency department presentation data collected by South Australia Health (SA Health) and lead in air and SO2 data collected by the South Australian Environment Protection Authority (SAEPA) were obtained and analysed to quantify health outcomes due to smelter emissions in Port Pirie. Regression analysis was used to assess the relationship between the concentration of lead in air and children's blood lead levels between the years of available data: 2003 to 2017. Ambient SO2 concentrations (SAEPA) measured continuously between 2008 and 2018 were 24-hour averaged and compared to daily local emergency department respiratory presentation rates (available from July 2012 to October 2018). Rates of emergency department respiratory presentations at Port Pirie and regional comparators were calculated as age-standardised rates. RESULTS: The data show that increases in ambient SO2 concentrations are associated with increased rates of emergency department respiratory presentations of Port Pirie residents, in which children are over-represented. The 30-day rolling average of respiratory presentations was significantly associated (p < 0.05) with incremental increases in SO2. Analysis of the relationship between lead in air and blood lead shows that annual geometric mean air lead concentrations need to be <0.11 µg/m3 to ensure the geometric mean blood lead of Port Pirie children under 5 years is ≤5 µg/dL. For children aged 24 months, lead in air needs to be no greater than 0.082 µg/m3 (annual geometric mean) to ensure geometric mean blood lead does not exceed 5 µg/dL. CONCLUSION: Current smelting emissions continue to pose a clear risk of harm to Port Pirie children. Allowable emissions must be lowered significantly to limit adverse childhood health outcomes including respiratory illness and IQ, academic achievement and socio-behavioural problems that are associated with lead exposure at levels experienced by Port Pirie children. Current SO2 levels are likely to be responsible for increased rates of emergency department respiratory presentations in Port Pirie compared with other South Australian locations. As a minimum, Australian SO2 air quality standards need to be enforced in Port Pirie to better protect human health. Lead in air needs to be approximately 80% lower than the current national standard (0.5 µg/m3) to ensure that the geometric blood lead of children under 5 years is less than or equal to 5 µg/dL.

Human exposure and risk associated with trace element concentrations in indoor dust from Australian homes.

This study examines residential indoor dust from 224 homes in Sydney, Australia for trace element concentrations measured using portable X-ray Fluorescence (pXRF) and their potential risk of harm. Samples were collected as part of a citizen science program involving public participation via collection and submission of vacuum dust samples for analysis of their As, Cr, Cu, Mn, Ni, Pb and Zn concentrations. The upper 95% confidence level of the mean values for 224 samples (sieved to <250 µm) were 20.2 mg/kg As, 99.8 mg/kg Cr, 298 mg/kg Cu, 247 mg/kg Mn, 56.7 mg/kg Ni, 364 mg/kg Pb and 2437 mg/kg Zn. The spatial patterns and variations of the metals indicate high homogeneity across Sydney, but with noticeably higher Pb values in the older areas of the city. Potential hazard levels were assessed using United States Environmental Protection Agency's (US EPA) carcinogenic, non-carcinogenic and Integrated Exposure Uptake Biokinetic (IEUBK) model human health risk assessment tools for children and adults. US EPA hazard indexes (HI) for Cr and Pb were higher than the safe level of 1.0 for children. HI > 1 suggests potential non-carcinogenic health effects. Carcinogenic risks were estimated for As, Cr and Pb whose carcinogenic slope factors (CSF) were available. Only the risk factor for Cr exceeded the US EPA's carcinogenic threshold (1 × 10-4) for children. Children aged 1-2 years had the highest predicted mean child blood lead (PbB) of 4.6 µg/dL, with 19.2% potentially having PbB exceeding 5 µg/dL and 5.80% exceeding 10 µg/dL. The Cr and Pb levels measured in indoor dust therefore pose potentially significant adverse health risks to children.