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Great Lakes
Article:
Officials target mercury levels in
fish
By John Bronz
South Bend Tribune
Published November 13, 2006
LANSING -- The Department of Community Health (DCH) is
having difficulty creating health advisories for imported
and locally caught fish because it's hard to determine
where the fish is caught.
Take, for example, whitefish caught in the Great Lakes.
The Lake Superior whitefish is one of cleanest to eat,
measuring less than .005 parts per million (ppm) of mercury.
But for Lake Huron whitefish over 22 inches long it's
recommended that pregnant women and children eat only
one meal per month, and that men consume less than one
per week.
The warning is because of high polychlorinated biphenyls
and mercury levels, which are harmful to humans in a variety
of ways, such as damage to children's nervous system and
brain. In adults, it can cause vomiting, intestinal bleeding
and possibly kidney failure.
"One of the biggest problems is determining where
the fish come from to give an advisory. But we can't do
that because the fish are sent to distribution centers
in Chicago and other areas, and we can't tell if the whitefish
is Lake Michigan or Huron whitefish," said Corey
Groetsch, a DCH toxicologist.
"Most of the fish that are brought to these distribution
centers are from all the United States and Canada, and
this is usually when the sampling is done."
Federal Drug Administration toxicologist Michael Bolger
said, "The Great Lakes are not tested that often.
That would be done more at a local level. We take samples
from fish that have few samples."
The problem doesn't stop there. Canadian fish imported
into Michigan are not tested on a regular basis.
Sea Grant, a Marquette-based, federally funded program
through University of Michigan and Michigan State University
(MSU) runs programs with the commercial fishing industry.
It works with local fisheries, testing mercury and methylmercury
levels in lakes and rivers.
District Extension Sea Grant agent Ron Kinnunen said
more testing needs to be done on imported Canadian fish
because most of their whitefish are caught in inland lakes.
"The few studies done on Canadian fish show higher
levels of mercury, but because of the processing centers
it's difficult to determine where and how much mercury
is in the fish," said Kinnunen.
Inland lakes usually have higher amounts of mercury because
of soil and pollution.
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