David, I will address the microbiological health risks from eating
shellfish. Oysters and clams as you pointed out concentrate whatever is in
the water as they feed. They should be safe to eat in the USA and Canada if
you buy them from an approved commercial source. The federal and state
(provincial) regulatory agencies have spent many years trying to keep the
sewage away from where the shellfish are raised and they have been generally
successful. These same people are on the lookout for sources of pollution as
you described. In less developed parts of the World great caution is
advised. But there are still some dangers from naturally occurring
bacterial pathogens to be aware of -- Vibrio bacteria specifically. These
bacteria grow in muddy areas as the water warms in Summer (or in the gulf
most of the year); the same places where shellfish grow. There are several
species and one in particular is deadly --V. vulnificus (luckily most people
are able to fend off this infection). However some people with weakened
immunity may become infected. In 2004 there were 94 people who were
diagnosed with V. vulnificus infections in the USA, 38 unfortunately died.
Vibrio bacteria and viruses, like hepatitis A virus, can be killed by
thorough cooking. For clams, at least, this is more heat for a longer time
than usually occurs when the shells first pop open during steaming. If you
want to be sure to kill all the viruses and bacteria you better eat them in
stew or fry them. If you want to eat shellfish raw with minimal risk, you
would be advised to choose cold water areas during the winter. Bert
Bartleson (retired from the Washington State Department of Health)
-----Original Message-----
From: Conchologists List [mailto:[log in to unmask]] On Behalf Of
David Kirsh
Sent: Thursday, March 02, 2006 6:42 PM
To: [log in to unmask]
Subject: Re: Chesapeake oysters
I love oysters and clams but I've been cutting way back just because they
ARE filter feeders. Raw oysters are particularly delicious but are reputed
to be a more likely cause of hepatitis than cooked.
But is anyone up on whether there's testing of oysters and clams for heavy
metals, dioxins, and other man-made contaminants?
>As far as I'm concerned the way to
>properly prepare oysters is to shuck them and eat them raw on the
>half shell.
David Kirsh
To be a patriot, one had to say, and keep on saying, " Our country, right or
wrong," and urge on the little war. Have you not perceived that that phrase
is an insult to the nation?
- Mark Twain, "Glances at History," 1906
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