Human health risk and assessment of trace element contamination from indoor dust in Australian homes

Abstract

Theoretical thesis.Contains bibliographical references.Chapter 1. Introduction -- Chapter 2. Research method and approach -- Chapter 3. Human exposure and risk associated with trace element concentrations in indoor dust from Australian homes -- Chapter 4. The effect of particle size distribution and bioaccessibility on human health risk assessment for trace elements measured in indoor dust -- Chapter 5. Cancer and mutagenic risks from exposure to indoor dust assessed by integrating radiometric and geochemical measurements -- Chapter 6. Geochemical profile, accumulation and sources of trace elements in residential indoor dust from an industrial city -- Chapter 7. Discussion -- Chapter 8. Recommendations and conclusions -- Appendices.The focus of this study is on potentially toxic contaminants in residential indoor dust from Australia, but predominantly Sydney metropolitan area, in the New South Wales state of Australia. Residents were engaged to submit their samples and complete online questionnaire via Australian media and through platforms developed for an earlier citizen science project (VegeSafe). This thesis uses an exposome approach to better quantify the potential health risks to individuals that may arise from exposure to environmental-sourced trace element contaminants in residential indoor dust. The exposome approach is based on the premise that the toxicity of environmental contaminants depends on several factors including the amount of contaminant an individual is exposed to (dose), route of exposure, chemical species, age, gender, genetics, and nutritional status. Given the known high degree of toxicity of As, Cr(VI), Ni and Pb, these elements are often priority elements for exposure assessment and are considered in depth in this study. Other elements Cu, Mn, and Zn are also included because previous studies have identified their prevalence in urban environments from industrial sources. In addition, potential cancer and mutagenic health risks from exposure to radiation from the radioactive isotopes ²³⁸U, ²³²Th and ⁴⁰K in indoor dust were also examined. The chemical and mineralogical analytical methods used in this thesis include portable X-ray Fluorescence (pXRF) analysis, total reflection X-ray fluorescence (tXRF) spectrometry, gamma-ray spectrometry, X-ray diffractometer (XRD) analysis, Energy-Dispersion Spectrometer (EDS) analysis and scanning electron microscope (SEM) analysis....Overall, this thesis contributes to the growing body of research in exposure science that has examined the effectiveness of using indoor dust as a metric for residential exposure assessment. This thesis contains the first independent survey on gamma emitting radionuclides in indoor it also contains the largest study of Australian indoor dust with the aim of documenting the occurrence and distribution of natural radionuclides in indoor dust. This thesis data shows that Cr and Pb levels in indoor dust together with naturally occurring radiogenic elements ²³⁸U, ²³²Th and ⁴⁰K pose potentially significant adverse health risks to residents. To reduce exposure of residents to potentially environmental-sourced contaminants in indoor environment, residents were advised to adopt a suite of mitigation strategies such as adopting a no shoes policy, establishing entry system to capture pollutants and moisture, and using washable rugs. Where high levels of naturally occurring radionuclides are present, the national authority should provide exposure reduction guidance to existing residents.1 online resource (xxv, 242 pages