Zhao, Shizhen and Sweetman, Andrew and Jones, Kevin (2016) Modelling the fate and bioaccumulation potential of organic chemicals in China. PhD thesis, Lancaster University.
Final_thesis.pdf - Published Version
Available under License Creative Commons Attribution-NonCommercial-NoDerivs.
Download (8MB)
Abstract
An extensive array of chemicals are used in industry and commerce, many produced in large volumes, but their fate in the environment and corresponding exposure to organisms (including humans) has only been measured for a limited number of substances. Modelling tools have been demonstrated to be an economical alternative to measurement data for the assessment of chemical fate and exposure. Therefore, many fate and bioaccumulation models have been developed in Western countries while progress on the development of tools and legislation are relatively far behind in China. In this thesis, the application of modelling tools in environmental fate and exposure assessment of organic pollutants has been explored in China. The first aspect of this research was the adaptability of Western dietary exposure models to the Chinese population. In Paper I, three established Western-based exposure models were used for China using specific Chinese dietary scenarios and modified human characteristics to explore their potential adaptability to be used for the Chinese population. The second aspect was to explore the possibility of extending existing bioaccumulation models to a wider range of organic pollutants by incorporation of newly developed poly-parameter linear free energy relationships (pp-LFERs) for individual biological phases in Paper II. Compared to traditional single parameter(sp) KOW-based (sp-LFERs) methods, the pp-LFERs only indicated limited advantages when evaluated with measurements, implying that the choice of approach should be based on other factors beyond methodology of calculating partitioning coefficients (e.g.,accuracy of input data and uncertainty from biotransformation). The studies described in Paper III and Paper IV took polychlorinated biphenyls (PCBs) as a case study, to comprehensively evaluate and demonstrate the ability of a global dynamic fate model （BETR-Global） linked to a bioaccumulation model (ACC-HUMAN) in the reconstruction of historical trends and predicting future of emission trends and exposure profiles for the Chinese population. Meanwhile, controlling sources of intentional and unintentional emissions were thoroughly explored within China in Paper III. Paper IV more focused on human exposure under the combined effect of emission trends and dietary transition for the Chinese population. The delayed peak time of the human body burden of PCBs has mainly been caused by rapid dietary shifts and on-going emissions from sources, such as imported e-waste in China. The Large uncertainty in the prediction of human body burdens suggests that the choice of model system could be relevant for exposure assessment and that the model should be tailored to the system of interest. Finally, preliminary suggestions to conduct effective controlling measures were also made for the policy makers.