STATE OF THE  GREAT LAKES  2003
     CAN WE EAT THE FISH?
       Offshore Water Quality
    Issue: Chemical pollution, resulting in fish
consumption advisories, is found in the offshore waters
of the Great Lakes.

•  Contaminants found suspended in the Great
   Lakes water column include PCBs, dioxin,
   PAHs, and various heavy metals.

•  These persistent contaminants can be ingested
   or absorbed through the skin of Great Lakes
   fish species. The lipid (fat)-loving
   contaminants will accumulate in the tissue
   and trigger fish consumption advisories once
   they reach a concentration considered unsafe
   for human consumption.

•  The integrity of offshore waters can affect the
   entire food web and determine whether or not
   Great Lakes fish are safe to eat.

The Indicator - SOGL 2003
This indicator compares contaminant levels in
offshore waters to standards that are known to be
protective of aquatic and human health. Through
this process, contaminants are identified that
exceed protective concentrations.

Particular contaminants found at elevated levels
in the water column can be ingested by fish and
stored in their fatty tissue.  As these fish are
ingested by other fish,
the contaminants
accumulate at
increasingly higher
concentrations. Large
fish, the type most often
desired for human
consumption, are often
those  carrying the
largest amount of contaminants.
The Assessment
Many toxic chemicals still exist in the Great Lakes,
however, only a small number are identified as
"critical pollutants." Critical pollutants are those
that exceed concentrations established to protect
humans and aquatic organisms.

Organochlorines (OCs) are a major chemical class
identified as pollutants in the Great Lakes that
occasionally exceed protective concentrations.
OCs are persistent bioaccumulative contaminants
used previously to produce plastics, paints, dyes,
wood preservers, cleaning solvents, and
pesticides. Their presence in the basin is
declining over time, however, some OCs still pose
human and ecological health risks.

For example, dieldrin, an OC pesticide banned in
the 1970s, decreased more than 50 percent
between 1986 and 2000. However, concentrations
still exceed the state of New York's water quality
criterion for fish consumption and the protection
of human health by a factor of 50 to 300 times
(Figure 1).
                   Dieldrin Concentrations (ng/L)
                        • <0.15
                           0.15-0.20
                        •  0.20 +
                *•
                     •**"
                     ••  »
Figure 1. Spatial pattern of Great Lakes surface water
dieldrin concentrations for the period of 1997 to 2000.

-------
   CAN WE EAT THE FISH?
The Outlook
Although many contaminants are decreasing in
concentration, others may emerge over time
with the development of new technology and
industrial processes. Targeting contaminant
sources and reducing contaminant transfer to
the Lakes reduces environmental and human
health risks.

The Great Lakes Binational Toxics Strategy
focuses precisely on this objective:

The elimination of persistent toxic substances,
especially those which bioaccumulate, from the Great
Lakes basin.

This program and others not only seek to
reverse chemical contamination, but also to
prevent future contamination from occurring.
For More Information,,,
Visit the web site, www.binational.net, to access
the State of the Great Lakes 2003 and other
references reporting on the state of the Great
Lakes.
                                                                                        12/03

-------