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

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

Spatial distribution, accumulation and human health risk assessment of heavy metals in soil and groundwater of the Tano Basin, Ghana

Soil serves as a vast matrix for heavy metal accumulation and subsequent redistribution to critical aspects of the environment such as groundwater. Soil pollution study is essential for sustainable human health and ecosystem protection. This study provides vital insight into the fate, accumulation, interactions, and health risk posed by heavy metals in soil and groundwater by employing geochemical accumulation index (Igeo), risk assessment models and multivariate data analysis techniques such as principal component analysis (PCA), preference ranking organisation method for enrichment evaluation (PROMETHEE) and geometrical analysis for interactive aid (GAIA). The median I geo estimates show moderate to strong Pb accumulation levels whilst all the other metals indicate uncontaminated to moderate levels. The PCA output point to anthropogenic origin of Pb and Cd in the Tano Basin and surrounding communities. PROMETHEE-GAIA results indicate that Pb, Cd, Zn and Fe accumulated in the soil matrix may potentially leach into the groundwater resources. The carcinogenic lifetime risks posed by Pb, Cd, and Ni metals to adults are within the tolerable acceptable risk and thus do not present an immediate danger in the study area. Due to the significant toxicity, bioaccumulation and biomagnification properties of Pb and Cd in the environment, areas associated with significant anthropogenic activities require regular monitoring and evaluation in order to ensure that these metals are consistently below the regulatory limits. This study has further elucidated the subject of heavy metal pollution and is therefore expected to enhance sustainable protection of the environment and human health

Environmental sustainability assessment using dynamic Autoregressive-Distributed Lag simulations-Nexus between greenhouse gas emissions, biomass energy, food and economic growth

Increasing population demand has triggered the enhancement of food production, energy consumption and economic development, however, its impact on climate change has become a global concern. This study applied a novel environmental sustainability assessment tool using dynamic Autoregressive-Distributed Lag (ARDL) simulations for model estimation of the relationships between greenhouse gas (GHG) emissions, energy, biomass, food and economic growth for Australia using data spanning from 1970 to 2017. The study found an inversed-U shaped relationship between energy consumption and income level, showing a decarbonized and services economy, hence, improved energy efficiency. While energy consumption increases emissions by 0.4 to 2.8%, biomass consumption supports Australia's transition to a decarbonized economy by reducing GHG emissions by 0.13% and shifts the demand for fossil fuel. Food and energy consumption underpin socio-economic development and vice versa. However, food waste from production and consumption increases ecological footprint, implying a lost opportunity to improve food security and reduce environmental pressure from agricultural production. There is no single path to achieving environmental sustainability, nonetheless, the integrated approach applied in this study reveals conceptual tools which are applicable for decision making

Energy conversion efficiency of pyrolysis of chicken litter and rice husk biomass

Pyrolysis is a well-established method of converting biomass to different types of value-added products, such as high energy density biofuels and chemicals. In this work, chicken-litter waste and rice husk were pyrolyzed at different temperatures with the aim of investigating the thermal behavior and energy recovery potential of the feedstocks. Computer-aided thermal analysis and thermogravimetric analysis were employed to study the pyrolysis properties of each biomass in a temperature-controlled regime. The specific heats of chicken litter and rice husk samples during their pyrolysis and the energy content of their pyrolysis products were investigated to determine the energy required to complete the pyrolysis of each sample and the energy recovery potential of each pyrolytic product. Most of the volatile products were evolved at 350 to 450 °C with CO2, CO, and CH4 being the dominant gas products from both samples throughout the pyrolysis process. At 500 °C and at a heating rate of 10 °C/min, the gas, bio-oil, and biochar yields from chicken litter and rice husk were in the ranges of 18 to 19, 35 to 39, and 42 to 47 wt %, respectively, with a total recoverable energy value of 12.7 MJ/kg from chicken litter and 13.9 MJ/kg from rice husk. The energy consumed to heat the samples to the final pyrolysis temperature of 500 °C was also estimated to be 1.2 and 0.8 MJ per kilogram of chicken litter and rice husk, respectively. With the measured values, the efficiency of the pyrolysis of chicken litter and rice husk samples is estimated to be 84% and 89%, respectively, assuming the heat required to carry out the pyrolysis process is supplied by combustion of the evolved pyrolytic gas products. If the pyrolysis is instead driven by solar thermal energy, the overall efficiency will increase to 92% for the chicken litter and 94% for the rice husk pyrolysis

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