howgate (phowgate@rsc.co.uk)
Wed, 16 Jun 1999 11:04:47 +0100
Dear Dorothy
You asked for information relevant to cadmium concentrations in
cephalopods.
Farid Ahmed has a chapter, 'Trace metal contaminants in food' in the book
'Environmental contaminants in food', 1999, Moffat, C.F. & Whittle, K.J.
(eds), Sheffield Academic Press, Sheffield, pp 146-214, ISBN 1-85075-921-9.
It devotes several pages to cadmium and a table of cadmium levels in
various classes of foods shows a content of 350 microg/kg in
molluscs/crustacea compared with fish with 35 microg/kg. (Invertebrates
generally cannot regulate body burdens of heavy metals as vertebrates can).
The cited reference is a 1992 paper from UNEP. The associated text of
Ahmed's chapter gives examples of high cadmium levels in the heaptopancreas
of crustacean shellfish, but no data on cephalopod molluscs. A review by
GESAMP, 1991, 'Joint Group of Experts on the Scientific Aspects of Marine
Pollution. Review of potentially harmful substances: carcinogens. Reports
and Studies GESAMP 46',
International Maritime Organization, London, has a section on cadmium,
which refers to molluscs and crustacea bioconcentrating cadmium compared
with fish. Some data for hepatopancreas of crustacea are given, but none
for cephalopods. I see that this report refers to studies suggesting
cadmium is poorly absorbed from the gut so the risk of harm from consuming
products with high cadmium contents might not be as great as it appears.
The viscera of cephaolopods are not normally eaten, and the risk, as you
infer, comes from contamination of the mantle during storage of intact
fish. The GESAMP report claims that cadmium is bound to protein in the
hepatopancreas of crustacea, so if cadmium is also bound in a similar maner
in the kidneys of cephalopods, it might not leach readily into the edible
portion of the animal.
The WHO, Geneva, maintains a database, GEMS, on chemical contaminants in
foods and that might have the information you seek. More information on
this database, and other sources of data, is given in a chapter, also by
Ahmed, in the book referred to above.
Peter Howgate
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