BIOACCUMULATION AND BIOMAGNIFICATION - Marine Pollution: What Everyone Needs to Know - page 149

was caused by some kind of food poisoning, with contami-
nated fish and shellfish being the prime suspects. Hg in the
fish was finally linked to the disease. Hair samples were taken
from affected people and from the Minamata population in
general. In patients the maximum Hg level was 705 ppm (parts
per million), indicating very heavy exposure. In unaffected
Minamata residents the level was 191 ppm, compared to an
average level of 4 ppm for people living outside Minamata.
Are there any concerns about mercury pollution in
seafood today?
While gross pollution such as in Minamata is a thing of the
past, there are still two major concerns. One is eating fish from
mercury-contaminated areas. Agencies in each state moni-
tor fish for the presence of contaminants and alert the public
through bans (closures) and advisories when a threat to human
health may occur from the consumption of contaminated fish.
In waters with bans, possession and consumption of fish and/
or shellfish is prohibited. An advisory is a recommendation to
limit consumption to specified quantities, species, and sizes
of fish. Those areas that are known to have elevated Hg will
have commercial fishing prohibited and have warning signs
for recreational fishers to not eat the fish. It is not known how
many anglers ignore these signs in favor of a free meal (with
no extra charge for the mercury).
The second major concern is the buildup of Hg in large car-
nivorous fishes that are not from contaminated areas, but are
high in the food web. This Hg comes mostly from atmospheric
sources, especially from burning of coal in power plants.
While other industries have had considerable reductions in
emissions, Hg pollution from electric utilities is still of con-
cern. The Hg released from coal burning power plants near
coastal areas goes into the air and eventually comes down into
the ocean. Over the past century, Hg in the surface ocean has
more than doubled. Nearly all fish and shellfish contain traces