It was shocking to hear that China had banned imports of clams
and oysters from most of the U.S. West Coast, This announcement
came after Chinese health inspectors reported high levels of
paralytic shellfish poison and arsenic in two shipments of geoducks
coming into that country. (KUOW
had the initial report.)
Photo: Washington Sea Grant
It turns out that one shipment of geoducks came from Poverty Bay
near Federal Way in Puget Sound, and the other one came from
Washington state government as well as the state’s extensive
shellfish industry pride themselves on a monitoring program
designed to ensure that PSP levels for harvested geoducks remain
well within safe limits. I frequently report PSP (“red tide”)
closures when they occur on recreational beaches — and commercial
shellfish are checked even more frequently.
The monitoring program for Washington state shellfish is
recognized worldwide for its ability to keep unsafe shellfish off
initial memo (PDF 33 KB) from the Chinese government said
inspectors had found levels of PSP at 30.2 mouse units per gram.
Mouse units? I had never heard of such a measurement, although I
know that live mice are often used in the monitoring tests. I
learned that “mouse units” was an older standard of measurement,
replaced by micrograms of toxin per 100 grams of shellfish
The use of mouse units was the first issue that threw everybody
off. I received an explanation from Jerry Borchert of the state’s
Office of Shellfish and Water Protection, and I offered this
explanation in a story I wrote for
today’s Kitsap Sun (subscription):
“The Dec. 3 letter imposing the shellfish embargo stated that
paralytic shellfish poison was found in concentrations of 30.2
mouse-units per gram. Mouse-units are an older standard, based on
the amount of poison it takes to kill a mouse. The more common
measurement today is micrograms of toxin per 100 kilograms of
shellfish tissue, Borchert said.
“‘We need to know what conversion factors they used,’ he said.
‘Based on the best information we have, which is sketchy, the
levels were between 600 and 1,500 micrograms per 100 grams.’
“In contrast, reports on geoducks from the Poverty Bay tract
were no greater than 62 micrograms between Sept. 26 and Oct. 24,
according to a health investigation completed Friday. The most
likely harvest date was found to be Oct. 5.
“Authorities will close an area when the toxin level reaches 80.
In fact, the high toxin levels suggested by the Chinese memo might
not have been reached in geoducks found anywhere in Puget Sound
this year, Borchert said.”
You can read the report,
“Investigation and Results Related to the Geoduck Shipment Linked
to the Shellfish Import Ban Imposed by China” (PDF 209 KB).
Confusion over the toxin levels found by the Chinese inspectors
has created a great deal of anxiety throughout state government and
the shellfish industry in Washington state. Nobody wants to say
that the Chinese made a mistake, especially when the only data
available is a terse finding in a
memo (PDF 33 KB) transmitted to U.S. authorities. In fact,
everyone I have talked to has been careful not to say anything
negative at all until the facts are all in.
The chance that the shellfish exported to China exceeded the
international standard of 80 micrograms per 100 grams seems
possible, given that samples sent to state officials reached 62.
That could invoke a response, even though the action level of 80 is
considered within a significant margin of safety. But if the
Chinese inspectors are reporting toxin levels higher than 600, that
raises other issues.
What about poaching? I think it would be hard to rule out the
possibility that somebody illegally sold geoducks from another area
where PSP levels were higher and said they were from Poverty Bay.
Whether that could happen depends, at least in part, on how well
officials are able to track the geoducks through the market.
John Weymer of the Puyallup Tribe told me that officials were
able to track the geoducks in question back to a specific boat
working in Poverty Bay. Since it was a harvest by the Puyallup
Tribe, tribal inspectors were on hand to make sure that the
harvested geoducks were accounted for until sold to an independent
buyer, he said. There is no doubt, he added, that the geoducks sold
from the bay in October met health standards.
Although numerous areas of Puget Sound showed toxin levels above
80 micrograms in some types of shellfish, I’m told that the number
of areas that reached 600 to 1,500 in geoducks were rare, if that
happened at all. Such a finding would create more doubt about the
accuracy of the Chinese testing.
One of the things I wondered about was whether the Chinese could
be acting in retaliation for ongoing U.S. actions regarding the
safety of foods imported from China. Bans on Chinese chicken were
imposed and then lifted, amid Chinese complaints to the World Trade
Organization. Questions of food safety have become entangled in
issues of fair trade between the two countries.
I’ve raised this question of a trade battle with several people.
Most tell me that if this were a trade issue, the Chinese would
have used the opportunity to make a political statement. Instead,
the Chinese memo was limited in scope, although the financial
impact to the Washington shellfish industry could be
Some people are quietly speculating that the Chinese have taken
this action to manipulate prices. If geoduck harvesting is shut
down in Washington state, the price of wild geoducks from the U.S.
will drop and markets will improve for Canadian and Mexican
geoducks. I’m told that the Chinese can make more money operating
in those countries, although I have been unable to verify that so
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