Future Health Research
Mercury is still a significant health concern for
Surveys of high-intake North America fish consumers with
elevated mercury exposures should be undertaken.
human fish consumers and wildlife. In the United
Valuable epidemiological information could be obtained on
States a total of 2,242 fish advisories exist for
similarities and differences between other mercury health
studies as well as the effects of co-contaminants such as
mercury, dominating all other chemical based fish
PCBs and selenium. Only one major study has evaluated
advisories (U.S. EPA 2001a). Due to widespread
the health effects caused by exposure to both PCBs and
mercury contamination of sportfish, all Great Lakes
mercury (Grandjean et al., 1997). The range of U.S. EPAs
Reference Dose and the Agency for Toxic Substances and
states and the province of Ontario have general
Disease Registrys Minimal Risk Level for chronic oral
fish consumption advisories covering all inland
mercury exposure reflects the uncertainty regarding the
other contaminants observed with mercury.
waters (U.S. EPA 2002a; Ontario Ministry of the
More information is needed on how the sources of mercury
tie into human exposure and health effects. Gathering
information on health effects of mercury from infancy
through old age would be of value.
be important contributors to lake acidification. Deforesta-
tion, wetlands, watershed size, and fishing pressures also
In establishing environmental health research protocols,
influence the amount of mercury in fish (Lucotte 2003).
there should be coordination between health researchers
Combustion sources and atmospheric loadings likely
in the North American community, including those doing
dominate mercury inputs to the majority of inland lakes
Arctic research. Health data in governmental repositories
(U.S. EPA 1997a).
should be evaluated to determine if it can be better
organized to permit the extraction of data.
Wildlife also are affected by mercury. Reproductive
impairment has been shown to occur in loons from
To better understand potential neurological associations
Minnesota lakes, Eastern Canada and Ontario where fish
and other health effects resulting from mercury exposures
mercury levels are above 0.4 ppm (Barr 1986; Meyer et al.,
in high intake fish consumers, including those living near
1998; Kenow 2003; Weiner 2002).
Areas of Concern where mercury levels in fish are elevated,
prospective information is needed on mercury in maternal
Information on mercury trends in the environment is very
hair and cord blood at the time of birth. Followup studies
limited, as data have not been collected for the purpose of
on infants and children would determine if cause-effect
assessing trends. Great Lakes fish such as smelt have
relationships with mercury exposure are occurring now.
shown gradual declines and sediments in open Great Lakes
While retrospective studies of cerebral palsy cases in
waters also show decreasing levels of mercury (U.S. EPA
Canadian Areas of Concern may be difficult and not yield
2003a). This is good news, but such data should not be
definitive information, it would be useful to further
viewed with complacency. Without pollution controls,
evaluate if a causal relationship with mercury exposure
increases in fossil fuel combustion, particularly coal,
exists. Further consultation with experts in mercury
around the world will increase atmospheric releases of
epidemiology is warranted.
mercury with potential impacts on the Great Lakes area.
Trends of mercury in fish and sediments from small inland
Integration of Risk Assessment, Risk Management and
lakes may be important sentinels and serve as an early
warning for future mercury problems in the Great Lakes.
Mercury fish consumption advisories, for some Areas of
As the mercury levels in fish are still above levels to fully
Concern and inland waters within the states and Canadian
protect human health and wildlife, further efforts to control
provinces, will exist for several decades. New and creative
mercury inputs and loadings must be undertaken. Based
risk communication measures should be developed to
on the high nutritional value of fish, lowering mercury
reduce mercury exposure resulting from sportfish and
burdens in fish will be intrinsically healthful for all who
commercial fish consumption. Recent advisories issued by
Ontario and the Great Lakes states consider both sportfish
and commercial fish consumption (WDH/WDNR 2002;
Ontario Ministry of the Environment 2002).