quantities and pathways are poorly understood at this time
of high-end fish consumers are close to those with
(Trip and Thorleifson, 1998).  Historical farming and
observable effects).  The population at highest
risk is the children of women who consumed
recreational lands pesticide applications were a significant
source of mercury input into the environment. The long-
large amounts of fish and seafood during
term fate of mercury from these practices is not well
pregnancy.  The committee concludes that the
understood and should be quantified with respect to
risks to that population is likely to be sufficient
groundwater, soil and atmospheric re-emissions.
to result in an increase in the number of children
who have to struggle to keep up in school and
While mass balance approaches and additional science will
who might require remedial classes or special
help elucidate mercury sources, loadings, and fate,
continued steps can be taken now at the local and regional
level to reduce mercury in products and waste streams.
Based upon findings presented at the mercury workshop
and conclusions from the NRC evaluation, some high-
Lowering mercury releases is good public health policy.
intake Great Lakes area women fish consumers would be
expected to have mercury exposures resulting in adverse
health effects to children.
... steps can be taken now at the local and regional
Mercury Levels in Great Lakes Region Biota
level  to  reduce  mercury  in  products  and  waste
streams.  Lowering mercury releases is good public
Mercury is still a significant health concern for human fish
consumers and wildlife.  In the United States a total of
health policy.
2,242 fish advisories exist for mercury, dominating all other
chemical based fish advisories (U.S. EPA 2001a).  Due to
widespread mercury contamination of sportfish, all Great
Lakes states and the province of Ontario have general fish
Mercury Exposure and Human Health Effects
consumption advisories covering all inland waters (U.S.
EPA 2002a; Ontario Ministry of the Environment 2002).
Adverse health effects resulting from mercury exposure via
Women of child bearing age and children under 15 are
fish consumption have been seen in several locations
advised not to consume more than a meal per week (or
around the world (NRC 2000; ATSDR 1999).  Mercury
four meals per month) of sportfish.  National advisories
causes subtle, adverse neurological health impacts at very
have also been issued by U.S. EPA regarding sport fish
low doses (NRC 2000; ATSDR 1999).  Recent studies
consumption and by the U.S. FDA on commercial fish
suggest that mercury may be associated with increased risk
consumption (U.S. EPA 2001a, b; U.S. FDA 2001).
of myocardial infarction in men (Guallar et al., 2002;
Yoskizawa et al., 2002 ).   Mercury exhibits characteristics
While mercury levels in Great Lakes fish have declined due
similar to lead toxicity and as more information is discov-
to regulation of point sources of mercury, some Areas of
ered regarding mercury toxicity, the exposure level at
Concern, such as the St. Clair River, Detroit River/Lake St
which mercury causes adverse health effects has been
Clair, Torch Lake and Deer Lake, still have sport fish with
lowered (NRC 2000).
mercury considerably above acceptable values to protect
human health (MDEQ 2003; MDCH 2002; Weis 2003).
Current mercury exposures in some high intake fish
Mercury levels below 0.1 ppm are needed to protect high
consumers in the Great Lakes region are above blood levels
intake fish consumers, using U.S. EPA’s recent Reference
(5.8 ppb, from U.S. EPA’s Reference Dose) of potential
Dose for mercury (U.S. EPA 2001a).  Mercury in larger size
health concern (Cole 2003).  In several other locations
predator sport fish, such as walleye, can exceed 1 ppm in
outside North America, children born of women having
some Areas of Concern (MDEQ 2003; Day 2003).   Investi-
elevated levels of mercury in blood or hair from fish
gations of sediments and near shore soils should be
consumption have been found to have a range of neuro-
undertaken in Areas of Concern where mercury levels in
logical and neuropsychological deficits, as shown in the
fish are elevated and where current or historical industrial
National Research Council’s (National Academy of Sci-
sources of mercury have been found.
ences) evaluation (NRC 2000).  The NRC reached the
following conclusions:
Outside the Great Lakes, mercury is a problem for inland
lakes, especially those where methylation of mercury is
“ . . . individuals with high methylmercury
favored (Weiner 2002).  Water acidity increases mercury
exposure from frequent fish consumption might
methylation and bioavailability (NRC 2000; Weiner 2002).
have little or no margin of safety (i.e. exposures
Nitrogen and sulfur oxides loadings into inland lakes may