Food chain contamination

Figure 1. Conceptual model illustrating examples of major anthropogenic contaminant sources and contaminants, their distribution within the abiotic environmental media, their movement into biota with potential food chain contamination, and potential effects at the organismal, population, conmiunity and ecosystem level of organization.

The environmental burden of waterways with polychlorinated dibenzo-p-dioxins (PCDD) has been at the forefront of public and regulatory concern, because of the toxicity associated with particularly the 2,3,7,8-(laterally) substituted congeners, which have a tendency to bioaccumulate throughout the trophic food chain. Contamination of aquatic sediments by dioxins includes both non-point (e.g., atmospheric deposition) and point sources (e.g., industrial effluents, combined sewage overflows), and is generally characterized by a dominance of hepta- and octa-CDD, with minor contributions of hexa- to tetra-CDD [429]. Elevated concentrations of the 2,3,7,8-TCDD isomer tend to be associated with direct discharge from sources such as 2,4,5-trichlorophenol production [54,430]. 

The Division of Chemistry and the Environment of the International Union of Pure and Applied Chemistry (IUPAC) has recently approved the creation of an IUPAC-sponsored book series entitled Biophysico-Chemical Processes in Environmental Systems to be published by John Wiley Sons, Hoboken, NJ. This series addresses the fundamentals of physical-chemical-biological interfacial interactions in the environment and the impacts on (1) the transformation, transport and fate of nutrients and pollutants, (2) food chain contamination and food quality and safety, and (3) ecosystem health, including human health. In contrast to classical books that focus largely on separate physical, chemical, and biological processes, this book series is unique in integrating the frontiers of knowledge on both fundamentals and impacts on interfacial interactions of these processes in the global environment. 

Compounds considered to be hydrolyzed rapidly are not prone to bioaccumulation, accumulation, food-chain contamination, or adsorption, and are not generally considered persistent, whereas the opposite is true for compounds not hydrolyzed rapidly. 

Bernard, A., Broeckaert, F., De Poorter, G. et al. (2002). The Belgian PCB/dioxin incident analysis of the food chain contamination and health risk evaluation. Environ. Res. 88 1-18. 

Logan, T. J. (1998). Impact of soil chemical reactions on food chain contamination and enviromnental quality. In Future Prospects for Soil Chemistry, ed. Huang, P. M., Sparks, D. L., and Boyd, S. A., Soil Science Society of America, Madison, WI, 191-204. 

Chromium (III) and Pu (III/IV) cations are sorbed to soil constituents and, thus, immobile in most aqueous and soil environments. On the other hand, Cr(VI) and Pu(VI) are quite mobile in soils and aqueous systems, because they are not sorbed by soil components to any extent. Therefore, in the hexavalent form, these elements are readily bioavailable (Amacher and Baker, 1982) and are of concern in food chain contamination. Chromium(III) and Pu(in/IV) can be oxidized to Cr(VI) and Pu(VI) by Mn(III/IV) oxides (Cleveland, 1970 Amacher and Baker, 1982). Manganese oxides can, thus, enhance the mobility and toxicity of Cr and Pu in soil and associated environments. 

Trace metals such as Cr(in), Pu(III), and Co(II) can be oxidized in the disproportionation process of Mn oxides and oxyhydroxides. Oxidation of trace metals can greatly influence their solubility and mobility. When Cr(III) and Pu(III/IV) are oxidized to Cr(VI) and Pu(VI), these elements are quite mobile, because they are not sorbed by soil components to any extent. Manganese oxide can thus enhance the mobility, toxicity, and food chain contamination of Cr and Pu. On the other hand, oxidation of Co(II) to Co(III) by Mn oxides decreases its solubility and mobility in soil and aquatic environments. 

Wormworth J. 1995. Toxins and tradition The impact of food-chain contamination on the Inuit of northern Quebec. Can Med Assoc J 152(8) 1237-1240. 

Biogeochemistry of soil cadmium and the impact on terrestrial food chain contamination... 

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