Abstract/Summary

Land contamination is an issue of concern in land regeneration and the built environment. To ensure the sustainability of the built environment, it is important that the risk to human health due to land contamination is addressed adequately. Current generic assessment criteria (GAC) values used in the assessment of contaminated land in the United Kingdom (UK) are very conservative. Although this is protective of human health, it may lead to un-necessary and costly remediation of land or result in land being left un-used. This highlights the need for improved understanding of human exposure to soil contaminants, which this work sought to promote. This thesis presents findings from our assessment of human exposure to five toxic elements; arsenic (As), cadmium (Cd), chromium (Cr), lead (Pb) and nickel (Ni), carried out using individuals who grow and consume their allotment produce. The primary exposure pathway investigated was oral ingestion through the consumption of produce. Concentrations of these elements were measured in samples of soil and produce. Site-specific risk assessment carried out using element concentrations and participants’ produce consumption data indicated no significant health risk to the participants. During the risk assessment process, it is necessary that element bioaccessibility values are determined and considered in the assessment to ensure that the risk is not over-estimated. To improve our understanding of actual human exposure to these elements though the oral ingestion pathway, we carried out biomonitoring and produced human physiologically-based kinetic models to assess internal exposure to these elements. Measured concentrations of blood Pb and urinary As, Cd, Cr and Ni were similar to the corresponding levels in the general (nonoccupationally exposed) populations in the UK; indicating that the participants were not exposed to these elements at levels importantly higher than other adults in the UK. In addition, this indicates that participants’ consumption of allotment produce did not result in them having significant additional exposure to the elements. The models, implemented in MATLAB, predicted the literature data and our biomonitoring data well. Because these models are capable of predicting internal exposure to these elements, they improve our understanding of exposure to the elements, which is important in the sustainable management of land contamination. To our knowledge, it is the first time combined biomonitoring and physiologically-based models for the five toxic elements have been used to assess exposure among allotment users.