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We have placed only the first paragraph of this paper here, you can download the pdf  HERE

Heavy metals in seafood – what is the risk to the consumer?

Ian C Shaw, Professor of Toxicology, University of Canterbury

This article is based on a lecture given at the 8th Annual Plant & Food Research Seafood Processing & Preservation Workshop, Nelson, New Zealand, March 2012.

 

Where do heavy metals come from? Heavy metals, including mercury (Hg), cadmium (Cd) and arsenic (As) are present in the earth’s crust and leach out into the terrestrial and aquatic environments, albeit at very low concentrations (Table 1). Transfer from the earth’s crust to the surface environment can be aided by geothermal activity – e.g. Cd concentrations are higher in volcanic regions. In addition, they have, or have had important industrial and commercial applications and are, or have been, mined. Mining results in further release from their crust-sequestered sites which leads to artificial enhancement of their normally very low environmental concentrations (Barbour & Shaw, 1999). Further to this, some heavy metals are co-deposited in the earth’s crust with useful metals that are valuable resources (e.g. Cd with zinc (Zn)) and so are commercially mined. The unwanted heavy metal contaminant (e.g. Cd) is then discarded with the mine tailings and leads to further environmental contamination. The use of fertilisers that might be contaminated with heavy metals (e.g. Cd) also adds to the environmental burden of these unwanted metals. Finally, the manufactured products incorporating heavy metals (e.g. Hg in long-life light bulbs) are returned to the earth (e.g. in landfill sites) at the end of their useful life which leads to further environmental contamination. Environmental concentrations of heavy metals are the result of addition of all, or some of these routes of contamination. When heavy metals are present in the terrestrial environment they are continually leached by rain and watercourses eventually entering the marine environment