To the OP. I went ahead and did my own research into the matter and I found that sea-food is in fact the major contributor to dietary intake of As as
well as various other elements.
A survey of people in Catalonia, Spain, found arsenic present in a number of food types. It is best summarised by the following figures, which I
copied from the paper (found
here*):
Additionally, the above study, which was performed in 2003, noted a significant decrease from previous surveys completed in 1998 by the same group.
Dietary habits were not found to have changed much, which makes it quite an interesting finding.
For shellfish, the levels of As are actually above the provisional tolerable weekly intake levels. However the authors go on to note that the As
present in shellfish is primarily found in organic compounds, so its toxicity is somewhat attenuated compared to that of the inorganic variety. Given
that only 0.02-11% of the As in shellfish is inorganic, the results they obtained are deemed acceptable for all age groups.
Another study (found
here*) I read noted the following in regards to
marine organisms:
Inorganic arsenic is not formed after ingestion of these compounds (Buchet et al., 1994, 1996), indicating little or no metabolism in humans to
the most toxic forms of arsenic. The complex arsenic compounds that predominate in marine organisms are much less acutely toxic than soluble inorganic
arsenic compounds, with arsenobetaine (the predo- minant compound in finfish) being virtually non- toxic (Shiomi, 1994; Yamauchi and Fowler, 1994).
Monomethylarsonic (MMA) and dimethylarsenic (DMA) acids are also less acutely toxic than the inorganic forms, arsenite (As3+) and arsenate
(As5+).
In regards to the comment about pasteurizing/cooking foodstuffs not decreasing As concentrations. In a lot of cases, cooking or heating food can
decrease the concentration of certain compounds. Specifically in regards to As, however, I found a paper
(
here*) that actually found there to be an increase in concentration depending on cooking
time and method. This is summarized by the following picture:
Regarding toxicity and expulsion from the body, I found
this paper,
which is very detailed and freely available. It's a very interesting read for anyone who's interesting and can handle the jargon.
* these papers are accessible only if you purchase them or have institutional access. If you have further queries regarding them, I do have access and
can divulge further. The abstracts to all of them are freely available.
edit on 17-9-2011 by hypervalentiodine because: (no reason given)
