Mercury Contamination

1
Mercury Contamination on Tribal Lands Leech Lake
Water Quality Program
2
Mercury Facts

• U.S. EPA estimates that more than 600,000
  children each year may be exposed to dangerous
  levels of mercury in the womb
• In 2002 health departments in 44 states issued
  advisories warning the public to limit or avoid
  their consumption of locally caught fish
• 17 states have issued statewide warnings that
  cover every lake and stream
• These warnings cover 12 million acres of lakes
  and 473,00 miles of streams
• High mercury levels in fish affect Tribes in
  which fishing is a part of their subsistence
  lifestyle and cultural tradition

3
Mercury Basics

• -Mercury is naturally occurring element that is
  present throughout the environment.
• -It is one of the transition metals on the
  Periodic Chart of Elements.
• - Mercury also forms salts mercury chloride
  (corrosive)
• -mercurous chloride (still used  in medicine)
• -mercury fulminate (used in explosives)
• -mercuric sulfide (paint pigment)
• -Mercury enters the atmosphere from natural
  processes such as volcano eruptions, groundwater
  seepage and evaporation from the oceans as well
  as human activity.
• -The majority of exposure in the U.S. is from
  methylmercury in fish

4
Forms of Mercury

• Mercury in the environment shifts among forms
• Organic mercury compounds
• Ex.)Methylmercury
• Can enter the body readily through lungs, skin
  and stomach
• Form of Hg found in fish
• Elemental Hg
• Liquid at room temperature
• Gives of vapor that can be inhaled into lungs and
  passed into bloodstream.
• Inorganic mercury compounds
• Can be absorbed through stomach if swallowed, or
  inhaled
• Found mainly in as salts or in medicines and
  cosmetics

5
Where is the Hg coming from?

• Coal-fired utility boilers
• Hazardous waste combustors
• Chlorine production
• Industrial boilers
• Medical waste incinerators
• Municipal waste incinerators
• Plants in the midwest and Texas create the
  majority of Hg emissions

6
Mercury Transport Pathways

• Wet/dry deposition of particulate Hg
• Volatilization
• Reduction or oxidation
• Photodegradation
• Methylation
• Hg is transfromed by sulfur bacteria
• Need carbon as a food source for energy
• 10 of Hg available is converted
• Sulfur contaminated rain also largely contributes
  to increased methylation (fish 10x more
  contaminated since the industrial revolution)
• Demethylation

7
Mercury to methlymercury

• -Once released, mercury can be deposited onto
  soil and into water bodies.
• -Bacteria in sediments convert mercury to
  methylmercury.
• -Taken up by tiny plants and animals
• -Fish that eat these organisms build up
  methylmercury in their bodies
• -As bigger fish eat smaller ones, the
  methylmercury is concentrated further up the
  food chain -"bioaccumulation
• -Therefore, the primary route of uptake is
  through human consumption of contaminated fish

8
Methlymercury bioaccumulation

• Easily absorbed through gastrointestinal system
• Total body burden of mercury is vital
• Hg concentrations are higher in larger, older
  predatory fish
• Tuna, Atlantic mackerel, shark and swordfish
• In Minnesota, walleye and northern pike
• Shrimp, canned light tuna, salmon, pollock and
  catfish have lower Hg content

9
Methylmercury basics

• -Food types seems to make no difference in
  absorption 95 of ingested MeHg is absorbed
• -MeHg is distributed throughout the body and
  easily passes the placenta and blood-brain
  barriers
• -Half-life of MeHg is approximately 70 days 
• -Good biomarkers of exposure Blood, hair and
  nails
• -Different forms of mercury may produce health
  effects in the same way (have a common mode of
  action)

10
Leech Lake Tribal lands

• Leech Lake Tribal lands contain 865,000 acres of
  water
• Wild rice grows abundantly and is harvested for
  subsistence by tribal members along with many
  species of fish.
• Each of these food sources is heavily impacted by
  Hg contamination and are widely used foods on the
  reservation
• In addition, other foods and medicinal sources
  may be equally affected.

11

• The total measured annual Hg input for Leech lake
  is 7.67 pounds of which 87 was atmospheric
  loading.
• The total export is 1.25 pounds and annual Hg
  stored is 6.42 pounds
• Mercury in Leech Lake calculated avg. of 0.39
  ppt, ranging from 0.22 to 0.94ppt.
• Mercury Loads to Leech Lake
• T5.394qci
• Qthe avg. daily flow for the period
• C the total Hg conc. of the water (mg/L)
• I the of days in the period
• Data taken from a water quality assessment of the
  Leech Lake Watershed July 1997 by the LLDRM and
  the MTC

12
Mercury consumption guidance

• Many state health agencies guidance for mercury
  concentrations in fish is 0.3- 0.5ppm (average
  American who consumes 5 lbs. of fish/yr.)
• Leech Lake Environmental Dept. and MCT utilize a
  subsistence threshold mercury fish tissue
  concentration consumption guideline of 0.02ppm
  based on consumption of 180 lbs./yr.
  (15lbs./month)

13
Mercury in fish from Leech Lake

• Ex) Mercury in Leech Lake Fish
• Northern pike 0.16 ug/g---1.9lbs. Fish
• Sucker 0.26 ug/g---2 lbs. Fish
• Walleye 0.26 ug/g---2lbs. Fish
• Muskie 0.15 ug/g---1.9 lbs. fish
• Bluegill 0.028 ug/g---0.2 lbs. fish
• Whitefish 2.8 ug/g----2.8 lbs. fish
• Larger the fish, more mercury. Predatory fish
  higher Hg concentrations as well.
• Data taken from Water quality assessment of the
  Leech Lake Watershed July 1997 by the LLDRM and
  the MTC

14
How are tribal lands more at risk?

• Subsistence lifestyles of tribes consume 40 times
  more fish and game than the average American.
• Many reservations within Minnesota and ceded
  territories which tribes hunt, fish and gather
  are located on or near wetlands where
  methylization is most likely to occur.
• When fishing tribes face consumption advisories,
  it is a hard decision to risk the health of the
  tribe or their tradition and cultural ways

15
Health effects from Hg

• Mercury is a well-known neurotoxin
• Shown to cause learning problems, memory loss,
  numbness, loss of muscle coordination, tremors,
  deafness and changes in vision
• Infants exposed to Hg in the womb are at risk for
  mental retardation, cerebral palsy and heart
  disease.
• Since fish, wild rice and game species are main
  food sources for tribes, it is unfortunate that
  the exposure to methylmercury is high.

16
Methylmercury Health Effects

• -Effects of exposure during development or to
  adults can cause mortality at very high levels
• -At lower doses, delayed responses, neurological
  effects, effects on tests related to ability to
  learn and process information may occur
• -Not likely to be a human carcinogen (Tumors are
  seen in animals only at extremely toxic doses
  neurological effects are observed at lower
  exposures)
• -Developing nervous system is a sensitive target
  for low dose MeHg exposure
• -Human and animal evidence shows cardiovascular
  effects
• -Animal evidence shows immune and reproductive
  effects

17
How do tribes address the threat of mercury
locally?

• There is a continuous effect to monitor, analyze
  and find areas of possible clean up of mercury
  contamination in and around their lands.
• Although, Mercury sampling is expensive and
  labor-intensive and not every tribe is funded to
  conduct research
• Public outreach to local tribes on the issues of
  mercury contamination
• For example, Fond du Lac Band of the Lake
  Superior Chippewa in MN have been monitoring Hg
  for 7 years.
• Sources in the area include coal-fired power
  plants within 150-200 miles, taconite plants that
  burn coal and some natural deposits.
• This tribe and many others in MN conduct
  mercury-deposition studies as well as fish-tissue
  and sediment sampling.

18
Local Tribal Studies

• Studies conducted at Fond du Lac Band of the Lake
  Superior Chippewa in MN have shown
• Hg levels are most elevated in shallow bodies of
  standing water, particularly where organic
  sediment is highest
• A third of the reservations major lakes show
  high levels of Hg
• 3,600 pounds of Hg was released in MN in 2000,
  and all but a fraction have volatized into our
  atmosphere.
• Those emissions were responsible for 10-30 of
  the total deposition in the state
• In addition, wild rice has not shown an elevated
  level of Hg, but has shown an elevated level in
  waterfowl that ingest wild rice
• Mercury impacts on the reservation are not only
  health threats to tribal members, but also to the
  cultural focus and income source for the tribe.

19
Federal Regulatory Responses

• In 2000, Clinton administration had set new
  mercury control proposals based research to cut
  mercury emissions by 50 by 2005.
• Within months, Bush administration rescinded the
  Clinton proposals and replaced them with reducing
  emissions by 30 by 2010 and 70 by 2018.
• In addition the Bush administration, has proposed
  that mercury be market-traded.
• Bush has also allowed for upgrades of up to 30
  of the facilitys worth with their having to
  install new pollution controls.

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Conclusion

• -Ingested methylmercury represents the major
  mercury exposure for most people, especially for
  Native Americans
• -Health hazards of methylmercury vary with
  exposure level and are based largely on
  observations in humans.
• -Recent and continuing studies of U.S.
  populations help us to better understand who is
  exposed to and at what levels of methylmercury.

21
References

• Kathryn R. Mahaffey, Ph.D., Methylmercury
  Epidemiological Update, USEPA, Washington D.C.,
  Fish Forum, 2004 5.
• John Walke, David Hawkins, and Linda Greer,
  National Resources Defense Council, press
  release, 5 Dec. 2003.
• 3 National Research Council, Toxicological
  Effects of Methylmercury, (National Academy
  Press, Washington, DC, 2000), 4.

• Editorial, Connect the Dots Whats Shaping
  Mercury Rules? Minneapolis Star Tribune, 18 Feb.
  2004.
• 5 Klaassen, C.D., (ed), Casarett and Doulls
  Toxicology. 5th ed., 1996, New York
  McGraw-Hill.

• Elizabeth Weise, Mercury Damage Irreversible,
  USA Today, 9 Feb. 2004 D6.
• http//www.epa.gov/air/mercuryrule/basic.htm
• 9 Bill Becker, State and Territorial Air
  Pollution Program Administrators/Association of
  Local Air Pollution Control Officials, press
  release, 25 Feb. 2004.
• Environmental Protection Agency, letter from
  Childrens Health Protection Advisory Committee
  to Michael Leavitt, 26 Jan. 2004.
• 11 US EPA Office of Water, Draft Mercury
  Deposition Modeling Results, 2003.

• Tom Atkeson, Don Axelrad, Curtis Pollman, Gerald
  Keeler, Integrating Atmospheric Mercury
  Deposition and Aquatic Cycling in the Florida
  Everglades, Florida Department of Environmental
  Protection,
• October 2002, revised November 2003 ii,iii.
• Hrabik, T.R., Watras, C.J., Recent declines in
  mercury concentration in a freshwater fishery
  isolating effects of de-acidification and
  decreased atmospheric mercury deposition in
  Little Rock Lake, Elsevier, The Science of the
  Total Environment, 297 (2002) 229-237.
• 14 National Wildlife Federation, Mercury
  Deposition Clean the Rain, February 2004.