Theoretical and Experimental Approaches to Describe the Chemodynamics of Hydrophobic Organics, Ionogenic Organics and Methyl Mercury in the Food Chain

点击翻译按钮获取中文摘要

It is imperative that we can assess the risk that is associated with the use of organic chemicals. One such risk is that humans and wildlife are exposed to concentrations of chemicals that cause adverse effects. The huge number of chemicals in commerce often necessitates the application of prediction techniques in chemical risk assessment. The long-term vision of the PI's research program is to develop the capability to reliably predict time-variant chemical exposure of humans and wildlife from two pieces of information: the chemical's molecular structure and the nature of its use.The possibility of reaching toxic tissue concentrations is particularly high for bioaccumulative chemicals with slow elimination from the body. Until recently, it was believed that only hydrophobic organic compounds (HOCs) resistant to biotransformation are eliminated sufficiently slowly for efficient bioaccumulation to occur. However, more recently it was revealed that at least some ionogenic organic chemicals (IOCs) exhibit substantial bioaccumulation potential.The prediction tools we currently have available for bioaccumulation assessment were developed for neutral HOCs and are largely unsuited for IOCs. Yet, IOCs constitute a huge fraction of commercially available chemicals. The dearth of quantitative tools for the bioaccumulation assessment of IOCs is presently a serious obstacle to effective chemical management worldwide. We therefore propose (i) to develop, evaluate and apply in novel and insightful ways a toolbox of bioaccumulation models for HOCs and IOCs based on a mechanistic treatment of the relevant thermodynamic and kinetic phenomena, and (ii) to perform laboratory measurement of chemical properties and physiological characteristics required for the parameterization of such models.The new modeling tools that will be developed can be applied (i) to aid in the understanding of absorption, distribution, metabolism, and excretion processes and of the tissue distribution of important groups of contaminants (such as perfluorinated alkyl acids or hydroxylated polychlorinated biphenyls), (ii) to identify humans populations and individuals as well as wildlife species and food chains with particularly high exposure susceptibility to different substances, (iii) in support of human biomonitoring ">, and (iv) for exposure assessment and decision support, e.g. regarding the design and evaluation of effective intervention strategies aimed at reducing contaminant exposure of particularly vulnerable populations.