Title

Metal exposure in non-occupationally exposed pregnant women of Western Australia and contribution of environmental sources.

Date of Award

2011

Degree Type

Thesis

Degree Name

Doctor of Philosophy

School

School of Natural Sciences

Faculty

Computing, Health and Science

First Advisor

Dr. Mary Boyce

Second Advisor

Associate Professor Andrea Hinwood

Third Advisor

Mr. Peter McCafferty

Abstract

Metals pollution is a growing global concern and human exposure has been associated with increased chronic and acute health effects even at low metal concentrations (Hu et al., 2006; US EPA, 2007; Rice et al., 2010; UNEP, 2010). Sensitive members of the population, such as neonates, children and pregnant women, in particular, are at increased risk due to their biological vulnerability (Jarup, 2003; Ettinger et al., 2007; US EPA, 2007). While much literature has examined exposure to metal contaminants, focussing on exposures from point sources, few studies have explored exposure in pregnant women and the factors that may influence their exposure. This study examined the degree of cadmium, copper, lead, manganese, mercury, nickel and uranium exposure in non-occupationally exposed pregnant women and the factors and sources contributing to their exposure. Studies have shown that environmental media are potential sources of metals exposure for humans, and exposure in the general population can occur through inhalation of contaminated air, ingestion of contaminated drinking water and food, or by dermal contact. This study is one of the few conducted in Australia, where source identification was carried out on the basis of biological monitoring (personal exposure) and residential environmental concentrations. Source identification of metals using chemometrics was conducted to identify whether drinking water, soil and dust were potential sources of maternal exposure. A cross-sectional study design was used to assess the exposure of pregnant women aged between 19 and 44 years to specific metals. One hundred and nineteen women were recruited via local hospitals and the community in different locations across Western Australia (WA). Exposure assessment was undertaken using biological and environmental sampling in combination with questionnaire information. Cadmium, copper, lead, manganese, mercury, nickel and uranium concentrations were determined in blood, urine, drinking water, soil and dust samples provided by the participants. Inductively coupled plasma mass spectrometry (ICP-MS) was used to determine a broad range of metals in blood, urine and drinking water, and inductively coupled plasma atomic emission spectrometry (ICP-OES) for metals in soil and dust. The samples targeted for this study, were anticipated to contain low metal concentrations as the study involves a non-occupationally exposed population. Hence, sensitive analytical methods with improved detection limits were essential. Emphasis was given to blood analysis because it involves direct assessment of human exposure to metals and also because it has high matrix variability (IPCS, 2000; UNEP, 2008). Therefore, this study included the optimisation of the microwave digestion method for measuring a broad range of elements simultaneously in human blood using ICP-MS. In this study, most women recorded low concentrations of metals in blood and urine. Metals were detected in most samples with the exception of mercury in urine and nickel in blood. On the whole, the geometric mean blood and urinary cadmium, copper, lead, manganese and mercury concentrations of these pregnant Australian women were similar to or lower than ranges reported in the international literature. However, a few individuals, had high exposure concentrations especially cadmium and mercury, which have been shown to be associated with adverse health effects in other studies. The geometric mean blood and urinary nickel concentrations were elevated. Uranium concentrations in both blood and urine samples were high. The metal concentrations in drinking water, soil and dust samples were generally low, with the exception of uranium in dust. Regression analysis indicated that drinking water, soil and dust were not important contributors to maternal exposure at background concentrations, however, a chemometrics study revealed that mixed sources of environmental media may have significant contribution to metals exposure. Drinking water, soil and dust were identified as potential sources of metals in blood, but not in urine. Demographics, behaviours and lifestyle characteristics were found to be less contributing to maternal exposure but there were indications that diet and water supply might be important contributors. The results obtained provide some information on personal exposure concentrations of pregnant women residing in Western Australia resulting from non-occupational exposure to cadmium, copper, lead, manganese, mercury, nickel and uranium, which can be used as a benchmark for future studies. Furthermore, this study employed a chemometrics approach and specifically partial least squares (PLS) to identify the sources. This allowed the determination of sources contributing to human exposure at lower metal concentrations. Finally, the presence of high concentrations of cadmium, lead, manganese and mercury in some maternal blood and urine samples, and the generally elevated nickel and uranium concentrations are cause for concern. Further studies are required to better understanding the risks associated with metals exposure and so provide a safer environment for all.

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