United States
Environmental Protection
Agency
Office of Research and
Development
Washington DC 20460
EPA/600/R-00/073
September 2000
www.epa.gov
Mercury Research
Strategy
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On the Cover: This graphic, originally used on the cover of the Mercury Study Report to Congress
(Reportto Congress), depicts the pathway through which mercury contamination proceeds to
humans and wildlife. It emphasizes the transport, transformation, and fate of mercury through the
aquatic food web. Such a pathway includes the biological conversion of atmospherically-deposited
mercury to an organic form (i.e., methylmercury); the uptake and bioaccumulation of methylmercury
in fish, birds, and mammals; and the subsequent health effects on susceptible populations who
consume large quantities of methylmercury-contaminated fish such as women of child bearing age
(i.e. maternal/fetal pair), and young children. Prepared by the U. S. Environmental Protection
Agency (EPA), the Report to Congress supports a plausible link between anthropogenic releases of
mercury from industrial and combustion sources in the U.S. and the concentration of methylmercury
in fish. The Report to Congress, along with several other EPA reports, serve as drivers for the
preparation of the Mercury Research Strategy.
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EPA/600/R-00/073
September2000
Mercury Research Strategy
Office of Research and Development
National Risk Management Research Laboratory
U.S. Environmental Protection Agency
Cincinnati, OH 45268
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NOTICE
This document has been reviewed in accordance with U. S. Environmental Protection Agency policy and approved for
publication. Mention of trade names or commercial products does not constitute endorsement or recommendation for
use.
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FOREWORD
The U.S. Environmental Protection Agency (EPA) is charged by Congress with protecting the Nation's land, air, and
water resources. Under a mandate of national environmental laws, the Agency strives to formulate and implement actions
leading to a compatible balance between human activities and the ability of natural systems to support and nurture life.
To meet this mandate, EPA's Office of Research and Development (ORD) is providing data and technical support for
solving environmental problems today, and building a science knowledge base necessary to manage our ecological
resources wisely, understand how pollutants affect our health, and prevent or reduce environmental risks in the future.
The 1996 Strategic Plan for the Office of Research and Development, and subsequent updates, sets forth ORD's vision,
mission, and long-term research goals. The Strategic Plan thus serves as the foundation for all of the research strategies
and plans that ORD has developed, or is in the process of developing. As part of its strategic planning process, ORD
uses the risk paradigm to identify EPA's top research priorities for the future. This focus on the risk paradigm helps in
establishing the individual, high priority topics for which research strategies are prepared. One of the high priority
research topics identified as part of the strategic planning process deals with the assessment and management of mercury
and methylmercury risks.
The Mercury Research Strategy describes the strategic approach for ORD's mercury research program. Using as a
technical foundation the EPA 1997 Mercury Study Report to Congress, the Mercury Research Strategy presents the key
scientific questions to be addressed over the next five years. It also describes the research needed to answer those
questions. The Mercury Research Strategy not only provides strategic directions, but serves as an important budget
tool. It is central to the preparation of a multi-year implementation plan for mercury and methylmercury research. This
multi-year plan enables EPA to track the progress being made in the mercury research program, as required by the 1993
Government Performance and Results Act.
Much of the research described in the Mercury Research Strategy will be conducted by ORD's in-house laboratories and
assessment center. ORD's Science to Achieve Results (STAR) Grants Program is also sponsoring research to investigate
several of the identified research needs. In some cases, ORD scientists and engineers are already working in close
cooperation with federal and state organizations in conducting research on mercury and methylmercury. Many organiza-
tions may see opportunities to collaborate in one or more of the research areas described in the Mercury Research
Strategy. ORD welcomes such collaborations in addressing the needs identified and invites those interested to suggest
joint activities.
Norine E. Noonan, Ph.D.
Assistant Administrator
for Research and Development
in
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PEER REVIEW
Peer review is an important component of research strategy development. The peer review history for the Mercury
Research Strategy'is as follows:
Initial Internal Agency Review:
ORD Science Council:
Lead Reviewer:
Submitted for Comments
to the Draft Mercury
Research Strategy Peer
Review Panel:
External Peer Review:
Reviewers:
Tom Atkeson
Nicolas Bloom
Steven Gilbert
Cynthia Gilmour
Dennis Laudal
Leonard Levin
Steven Lindberg
Alan Stern
Kent Thornton
Brian Wheatley
Coordinated by:
Final Acceptance by ORD:
ORD Executive Lead:
September 1998
Final clearance
November 1998
Lee Mulkey, Ecology Associate
National Risk Management Research Laboratory
October 1999
December 8-9,1999; Washington, DC
Florida Department of Environmental Protection
Frontier Geosciences Inc.
SNBLUSA,Ltd.
The Academy of Natural Sciences, Estuarine Research Center
Energy & Environmental Research Center, University of North Dakota
Electric Power Research Institute
Oak Ridge National Laboratory
Department of Environmental and Community Medicine Robert Wood
Johnson Medical School - University of Medicine and Dentistry of
New Jersey
FTN Associates
Eco-Anth Consulting
Kate Schalk, Eastern Research Group, Inc.
September 2000
William Farland,NCEA
IV
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TABLE OF CONTENTS
1.0 INTRODUCTION 1
1.1 BACKGROUND 1
1.1.1 Exposure Route of Most Concern 2
1.2 INTERNATIONAL NEED TO ADDRESS MERCURY 3
1.3 MERCURYRESEARCHSTRATEGYORGANIZATION 3
2.0 PROBLEM DESCRIPTION 5
2.1 WHYMERCURYPOSESARISK 5
2.2 IMPACTSOFMETHYLMERCURYONHUMANHEALTHANDWILDLIFE 5
2.2.1 Human Health Impacts 5
2.2.2 Wildlife Impacts 7
2.3 MERCURYUSES AND RELEASES 8
2.3.1 Uses 8
2.3.2 Releases 8
2.4 MERCURYTRANSPORT, TRANSFORMATION, AND FATE 9
2.4.1 Transport 9
2.4.2 Transformation and Fate 9
2.5 MERCURYANDMETHYLMERCURYRISK MANAGEMENT 10
2.5.1 Risk Management 10
2.5.2 Risk Communication 10
3.0 REGULATORY ACTIONS AND OTHERFACTORS THATINFLUENCE
MERCURYRESEARCH PRIORITIES 11
3.1 NATIONALACADEMYOF SCIENCES REPORT 11
3.2 REGULATORY AND OTHERDOMESTIC COMMITMENTS 11
3.2.1 Regulatory Activities 11
3.2.2 Special Initiatives 13
3.2.3 International Activities 13
4.0 RESEARCH AND DATAGATHERING BY OTHERS 16
4.1 MERCURY AS ACROSS-MEDIA,MULTIDISCIPLINARYPROBLEM 16
4.2 FEDERAL ACTIVITIES 16
4.2.1 National Institutes of Health and the National Institute for Environmental Health Sciences 16
4.2.2 National Center for Health Statistics and the Food and Drug Administration 16
4.2.3 U.S. Geological Survey 16
4.2.4 Department of Defense 17
4.2.5 National Oceanic and Atmospheric Administration 17
4.2.6 Department of Energy 17
4.3 STATE AND REGIONAL ACTIVITIES 17
4.3.1 EPA's Region IV and the State of Florida 17
4.3.2 The New England States 17
4.3.3 Other Regional Contributors 18
4.4 PRIVATE SECTORACTIVITIES 18
4.4.1 The Electric Power Research Institute 18
4.4.2 The Chlorine Institute 18
4.5 OTHERDOMESTIC ACTIVITIES 18
4.5.1 Non-Governmental Organizations 18
4.5.2 Academic Institutions 19
4.6 INTERNATIONALACTIVITIES 19
4.7 CROSS-ORGANIZATIONAL ENGAGEMENT 19
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TABLE OF CONTENTS (cont.)
5.0 RESEARCH AREAS, KEY SCIENTIFIC QUESTIONS AND RESEARCH NEEDS 21
5.1 MERCURYRESEARCH PRIORITIES 21
5.1.1 Identification of Research Areas 21
5.1.2 Development of Key Scientific Questions 21
5.1.3 Prioritization of Research Areas and Key Scientific Questions 21
5.1.4 Identification of Research Needs 21
5.1.5 Prioritization of Research Needs 22
5.1.6 Peer Panel Review of the Mercury Research Strategy 22
5.2 TAKINGACTIONONIDENTIFIEDPRIORITIES 22
5.3 STRATEGIC DIRECTIONS 22
5.3.1 Transport, Transformation, and Fate 23
5.3.2 Risk Management for Combustion Sources 23
5.3.3 Risk Management for Non-Combustion Sources 23
5.3.4 Ecological Effects and Exposure 24
5.3.5 Human Health Effects and Exposure 24
5.3.6 Risk Communication 24
5.3.7 Strategic Directions Summary 24
5.4 DETAILED DISCUSSION OF RESEARCH AREAS, KEY SCIENTIFIC QUESTIONS, AND RESEARCH NEEDS 24
5.5 TRANSPORT, TRANSFORMATION AND FATE 24
5.5.1 Key Scientific Question 24
5.6 RISK MANAGEMENT FOR COMBUSTION SOURCES 29
5.6.1 Key Scientific Question 29
5.7 RISK MANAGEMENT FOR NON-COMBUSTION SOURCES 33
5.7.1 Key Scientific Question 33
5.8 ECOLOGICAL EFFECTS AND EXPOSURE 36
5.8.1 Key Scientific Question 36
5.9 HUMAN HEALTH EFFECTS AND EXPOSURE 39
5.9.1 Key Scientific Question 39
5.10 RISK COMMUNICATION 45
5.10.1 Key Scientific Question 45
6.0 ISSUES BEYONDTHEMERCURYRESEARCH STRATEGY 48
6.1 SCIENCE ACTIVITIES THAT GO BEYOND RESEARCH 48
6.1.1 Improving Mercury Emissions Inventories and Collecting Source Emissions Data 48
6.1.2 Monitoring Mercury in Various Media 48
6.1.3 Understanding the International Implications of Mercury 49
6.2 FOSTERING FUTURE RESEARCH PARTNERSHIPS 49
7.0 REFERENCES 50
APPENDIX A 53
VI
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LIST OF FIGURES
Figure 1. Mercury Fish Ingestion Exposure Pathway, the Focus of the Mercury Research Strategy. 2
Figure 2. Mercury-based Fish Consumption Advisories for North America (EPA, 1999a;EPA, 1999c) 6
FigureS. Research Emphases for Mercury Research Strategy Key Scientific Questions (FY2001-FY2005) 23
LIST OF TABLES
Table 1. Summary of Major Sources of Anthropogenic Mercury Air Emissions (EPA, 1997a) 8
Table 2. EPA Regulatory Activities Affecting Mercury Releases to the Environment 12
Table 3. International Mercury Activities that Support the Development of the Mercury Research Strategy. 14
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ACKNOWLEDGMENTS
The Mercury Research Strategy was prepared by Office of Research and Development scientists and engineers and
technical staff from EP A's Program Offices and Regions. Co-leaders for ORD were Jonathan Herrmann of the National
Risk Management Research Laboratory and Kathryn Mahaffey, formerly of the National Center for Environmental
Assessment, now with the Office of Prevention, Pesticides, and Toxic Substances. Major contributors included:
Human Health Team: Kathryn Mahaffey (Lead), Stan Barone (ORD), Winona Victery (Region IX), and Rita Schoeny
(OW)
Ecological Systems Team: Herman Gibb (Lead) (ORD), John Nichols (ORD), Randy Wentsel (ORD), Bob Frederick
(ORD), Keith Sappington (OW)
Fate and Transport Team: Tom Barnwell (Lead) (ORD), Robert Stevens (ORD), Jerry Stober (Region IV), Alex McBride
(OSWER), Arnold Kuzmack(OW), Bob Ambrose (ORD), Barbara Levinson (ORD), Angela Bandemehr(GLNPO), and
Russ Bullock (ORD)
Human Exposure Team: Arnold Kuzmack (Lead) (OW), Kathryn Mahaffey, Glenn Rice (ORD), Alexis Cain (Region V),
and Dale Pahl (ORD)
Risk Management for Combustion Sources Team: Douglas McKinney (Lead) (ORD), Jim Kilgroe (ORD), Ravi
Srivastava (ORD), Charles Sedman (ORD), Jeff Ryan (ORD), Susan Thorneloe (ORD), William Maxwell (OAR), Ellen
Brown (OAR), Chuck French (OAR), Carl Mazza (OAR)
Risk Management for Non-Combustion Sources Team: Ben Blaney (Lead) (ORD), Patricia Erickson (ORD), Ivars Licis
(ORD), Larry Jones (ORD), Paul Randall (ORD), Donald Sanning (ORD), John Kinsey (ORD), Frank Anscombe (Region V),
Tom Armitage (OW), Rita Chow (OSWER), Mary Cunningham (OSWER), Arnold Kuzmack (OW), Iliam Rosario (OAR),
Gary Sheth (Region IX), Gregory Susanke (OPPTS), and Jeri Weiss (Region I)
Risk Communication Team: Kathryn Mahaffey (Lead) and Jeffrey Bigler (OW)
International Team: Jonathan Herrmann (ORD), Marilyn Engle (OI A) (co-leads), Alan Van Arsdale (Region I), Brian
Muehling (OI A) Stanley Durkee (ORD), Doug Steele (ORD), Robert K. Stevens (ORD), and Angela Bandemehr (GLNPO)
Graphics and tables were prepared by John McCready (ORD). Numerous helpful comments were provided during several
reviews by EPA's Mercury Task Force. William Stelz and Barbara Levinson of ORD's National Center for Environmental
Research actively contributed to the development of the information on the STAR Grants Program. Jean Dye and Abby
Hill (ORD) and Yvonne Watson (SAIC) were most helpful in preparing the final version of the Mercury Research Strategy
and the response to peer reviewer comments.
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ACRONYMS
ACAP Arctic Council Action Plan
AEPS Arctic Environmental Protection Strategy
AMAP Arctic Monitoring and Assessment Program
APGs Annual Performance Goals
APMs Annual Performance Measures
ARL Atmospheric Research Laboratory
ATSDR Agency for Toxic Substances and Disease Registry
BAT Best Available Technology
BBDR Biologically Based Dose-Response
BIFs Boilers and Industrial Furnaces
BMDL Benchmark Dose Lower Bound
BNS Binational Toxics Strategy
CAA Clean Air Act
CEC Commission for Environmental Cooperation
CEMs Continuous Emission Monitors
CENR Committee on the Environment and Natural Resources
CETEM Center for Mineral Technology
DOD Department of Defense
DOE Department of Energy
DOS Department of State
ELA Experimental Lakes Area
EMAP Environmental Monitoring and Assessment Program
EPA Environmental Protection Agency
EPRI Electric Power Research Institute
EWG Environmental Working Group
FDA Food and Drug Administration
Gil Great Lakes Water Quality Initiative
GLNPO Great Lakes National Program Office
GPRA Government Performance and Results Act
HAPs Hazardous Air Pollutants
HC1 Hydrochloric Acid
Hg Mercury
Hg° Elemental Mercury Vapor
Hg+2 Gas-Phase Ionic Mercury
Hg Parti culate-Bound Mercury
HgCl2 Mercuric Chloride
HWIs Hazardous Waste Incinerators
ICR Information Collection Request
LCA Life Cycle Assessment
LDRs Land Disposal Restrictions
LOAEL Lowest Observed Adverse Effect Level
LRTAP Long Range Transboundary Air Pollution
MACT Maximum Achievable Control Technology
MCC APs Mercury-Cell Chlor Alkali Plants
MCM Mercury Cycling Model
MRL Minimal Risk Level
MRS Mercury Research Strategy
MTF Mercury Task Force
MWCs Municipal Waste Combustors
IX
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ACRONYMS (cont.)
MWIs Medical Waste Incinerators
NAAEC North American Agreement on Environmental Cooperation
NARAP North American Regional Action Plan
NAS National Academy of Sciences
NCEA National Center for Environmental Assessment
NCER National Center for Environmental Research
NCHS National Center for Health Statistics
NEG/ECP New England Governors/Eastern Canadian Premiers
NEP National Estuary Program
NERRS National Estuarine Research Reserves System
NESCAUM Northeast States for Coordinated Air Use Management
NETL National Energy Technology Laboratory
NHANES National Health and Nutrition Examination Survey
NHEERL National Health and Environmental Effects Research Laboratory
NIH National Institutes of Health
MEHS National Institute for Environmental Health Sciences
NOAA National Oceanic and Atmospheric Administration
NOAEL No Observed Adverse Effect Level
NOx Oxides of Nitrogen
NRC National Research Council
NRDC National Resources Defense Council
NRMRL National Risk Management Research Laboratory
NTI National Toxics Inventory
NWF National Wildlife Federation
OAQPS Office of Air Quality Planning and Standards
OAR Office of Air and Radiation
OERR Office of Emergency and Remedial Response
OIA Office of International Activities
OPPTS Office of Prevention, Pesticides, and Toxic Substances
ORD Office of Research and Development
ORNL Oak Ridge National Laboratory
OSTP Office of Science and Technology Policy
OSW Office of Solid Waste
OSWER Office of Solid Waste and Emergency Response
OW Office of Water
PAC Powdered Activated Carbon
PAME Protection of the Arctic Marine Environment
PBPK Physiologically-Based Pharmacokinetics
PBTs Persistent, Bioaccumulative Toxics
PCBs Polychlorinated Biphenyls
PM Paniculate Matter
ppb Parts Per Billion
ppm Parts Per Million
RCRA Resource Conservation and Recovery Act
RELMAP Regional Lagrangian Model of Air Pollution
RFA Request for Application
RfD Reference Dose
RGM Reactive Gaseous Mercury
SMOC Sound Management of Chemicals
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ACRONYMS (cont.)
SO2 Sulfur Dioxide
SO3 Sulfur Trioxide
STAR Science to Achieve Results
TCDD 2,3,7,8-tetrachlorodibenzo-p-dioxin
TMDLs Total Maximum Daily Loads
TRI Toxics Release Inventory
UNECE United Nations Economic Commission for Europe
USGS United States Geological Survey
WC Wildlife Criterion
WHO World Health Organization
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EXECUTIVE SUMMARY
INTRODUCTION
The Mercury Research Strategy (MRS) guides the Office of Research and Development (ORD) mercury
research program. Mercury has been identified as an important human health and environmental
problem in a number of U.S. Environmental Protection Agency (EPA) documents such as the Study of
Hazardous Air Pollutant Emissions from Electric Utility Steam Generating Units - Final Report to
Congress (EPA, 1998b) and the Deposition of Air Pollutants to the Great Waters: Third Report to
Congress (EPA, 2000a). The MRS, called for in EPA's draft Mercury Action Plan (Federal Register,
1998), covers F Y2001- 2005. It summarizes the human health and ecological risks posed by mercury and
methylmercury, and indicates that mercury needs to be considered on local, regional, and global scales.
The MJ?S'identifies the key scientific questions of greatest importance to the Agency. It then describes
a research program to answer those questions. The goal of the MRS is to reduce the scientific uncer-
tainties that limit EPA's ability to assess and manage mercury and methylmercury risks. ORD will use
the Mercury Research Strategy to develop a multi-year implementation plan in F Y 2001 for its mercury
research program.
In conducting the mercury research program, in-house research efforts by ORD's laboratories and
assessment center will be coupled with those of ORD's Science to Achieve Results (STAR) Grants
Program. The STAR Grants Program sponsors extramural research with academic institutions and other
not-for-profit entities. Also, some of the research described in the MJ?S'vfi\\ be undertaken in coopera-
tion with organizations such as the Department of Energy and the U.S. Geological Survey. The MRS
provides information on research needs and priorities that can be used by various stakeholders outside
of the Agency, including researchers in other federal agencies, states, private industry, not-for-profit
organizations, and academia. It may well assist them in planning their own mercury research activities
and programs. Finally, the Mercury Research Strategy suggests that other scientific data and informa-
tion not generally considered "research" are needed, such as inventories of sources and routine
multimedia monitoring.
EPA Report: Mercury Study Report to Congress
The Mercury Study Report to Congress (Report to Congress) (EPA, 1997a) described the magnitude of
mercury emissions in the United States, identified mercury emission sources, assessed the health and
environmental implications of those emissions, and evaluated the availability and cost of technologies
for emission control. It is the most comprehensive human health and environmental investigation of
mercury and methylmercury available. The Report to Congress serves as the foundation for EPA's
understanding of the risk assessment and risk management issues associated with mercury and
methylmercury. It contributes significantly to the strategic directions and the key scientific questions
posed in the Mercury Research Strategy.
In the Report to Congress, EPA concluded that a plausible link exists between human activities that
release mercury from industrial and combustion sources in the United States and methylmercury
concentrations in humans and wildlife. In preparing the report, EPA conducted a quantitative human
health risk assessment of methylmercury. The assessment estimated that between one and three
percent of women of childbearing age (i.e., between the ages of 15 and 44 years) in the United States eat
sufficient amounts offish for their fetuses to be at risk from methylmercury exposure. The Mercury
Study Report to Congress also concluded that mercury poses risks to various wildlife, including some
birds and fur bearing mammals such as loons, mink, and otters. The Report to Congress comprehen-
sively identified research needs to improve both mercury risk assessment and risk management.
NAS Report: Toxicological Effects of Methylmercury
The National Academy of Sciences (NAS) report on the Toxicological Effects of Methylmercury Q39£,
2000) confirmed EPA's Reference Dose (RfD) of 0.1 micrograms per kilogram of body weight per day. It
viewed this RfD as a scientifically justifiable level for protecting human health from the adverse effects
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of methylmercury. The NAS report estimated that more than 60,000 U.S. children are born each year
with a risk of damaged nervous systems from methylmercury exposures in the womb. It also noted
reduced performance on neuropsychological tests in recent epidemiological studies, suggesting that
prenatal methylmercury exposure is likely to be associated with poorer school performance. The NAS
report identified research needs related to: better characterization of methylmercury heath effects,
enhanced estimation of methylmercury dose-response relationships, and improved characterization of
risk from current methylmercury exposures. Finally, the NAS report recommended that every effort be
made to establish a common scientific basis for exposure guidance among federal agencies, recognizing
that each is responsible under differing legal and regulatory authorities.
MERCURYIN THE ENVIRONMENT
As a liquid at room temperature, mercury is a unique metal that has proven itself useful for centuries in
both industrial and consumer applications. Mercury is released in elemental and oxidized forms from a
variety of human (i.e., anthropogenic) activities and natural sources. The Mercury Study Report to
Congress (EPA, 1997a) found that the exposure pathway of greatest concern is that of fish consump-
tion. This pathway is the one emphasized in the Mercury Research Strategy and involves the follow-
ing: (1) emission of mercury to the air; (2) mercury air transport, transformation, and deposition on land
and water; (3) transformation of mercury to methylmercury in water bodies; (4) methylmercury uptake
and bioaccumulation in fish; and (5) consumption of contaminated fish by mammals, including humans.
Mercury and methylmercury exposures can result in permanent damage to the brain and kidneys in both
humans and wildlife.
The intentional use of mercury in products (e.g., batteries, paints) in the United States has decreased
significantly in the past twenty years (Sznopoek and Goonan, 2000). Since the 19th Century, however,
the total amount of mercury in the environment has grown by a factor of two to five above pre-indus-
trial levels (Mason, et. al., 1994). This situation raises concerns about increasing amounts of mercury in
the global pool and the implications of mercury emissions and their impacts on both people and
ecosystems worldwide. In the United States, the most significant releases of mercury to the environ-
ment are emissions to the air. These air emissions come from combustion sources, such as power plants
or incinerators (mercury from human activities). Mercury is also released from geologically bound
sources through natural processes {e.g., volcanos, fires) and through mass transfer to the atmosphere
by biologic and geologic processes from mercury that has been previously deposited (i.e., re-emitted
sources). In addition to air emissions, mercury is also released in other ways, including waterborne
discharges and direct disposal to the land. The release of mercury to water and land are believed to be
small compared to air emissions, but these releases can have significant local effects.
Depending on the chemical form in which it is released, the stack height of the source, air movement
patterns, and other factors, mercury can deposit at local, regional and global scales.
• Locally, the 3 0-mile radius from some sources can have a relatively high percentage of mercury
depositing on land and water.
• Regionally, different areas of the country experience different amounts of mercury deposition; the
combined emissions of several mercury sources can travel hundreds of miles and deposit in other
regions of the United States.
• Globally, mercury from other countries deposits in the United States, and U.S. emissions can travel
around the world and then deposit back on U.S. soil and water.
Modeling by EPA concluded that the highest regional deposition rates from U.S. anthropogenic
mercury sources occur in the southern Great Lakes and Ohio Valley, the Northeast, and scattered areas
in the Southeastern United States (EPA, 1997a).
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The particular form of mercury emitted is important in determining whether it is deposited near its
emission source or travels great distances, perhaps circling the globe several times before eventually
depositing. Mercury emissions from human activities are comprised of various inorganic forms,
including elemental mercury vapor, gas-phase ionic mercury, and particulate-bound mercury. Once
deposited in the environment, these inorganic forms can be converted by naturally occurring processes
into the highly toxic organic form — methylmer-
cury. The greatest concern regarding methylmer-
cury is the neurotoxic health effects associated
with in utero exposures. Children exposed after
birth are potentially more sensitive to the toxic
effects of methylmercury than adults because
their nervous systems are still developing.
Mercury also poses risks to wildlife, including
some birds and mammals, such as loons, mink,
and otters.
Mercury Research Strategy Goal
To provide information and data that
reduce scientific uncertainties limiting the
Agency's ability to assess and manage
mercury and methylmercury risks.
MERCURYRESEARCH STRATEGY SCOPE
ORD's mercury research program provides information, methods, models and data to address the key
scientific questions of greatest concern to EPA. The Mercury Research Strategy goal seeks to reduce
scientific uncertainties related to mercury and methylmercury. The J^Kiypresents the strategic direc-
tions for the mercury research program over the next five years. It will assist ORD in the development
of a multi-year implementation plan and will help in making decisions about future mercury research
priorities. The results of the research program will inform the Agency's Program Offices and Regions
on their actions to assess and manage mercury and methylmercury risks. The Mercury Research
Strategy is oriented to domestic mercury and methylmercury issues, although most of the research
results will also be useful internationally. In preparing the Mercury Research Strategy, six key scientific
questions, associated research areas, and related research needs were identified. While it is a five-year
research strategy, the MRS will undergo updates and adjustments based on ORD's annual research
planning process.
While the NAS report confirmed EPA's reference dose for methylmercury, additional data and informa-
tion are needed to answer a number of key scientific questions on risk assessment and risk management
of mercury and methylmercury. ORD's Mercury
Research Strategy is part of the Agency's Sound
Science, Improved Understanding of Environ-
mental Risk, and Greater Innovation to Address
Environmental Problems Goal (Goal 8).
Implementation of Goal 8 is the responsibility of
EPA's Office of Research and Development
under the Government Performance and Results
Act (GPRA) (EPA, 2000b). Although assigned to
Goal 8, ORD's mercury research program
supports a number of other GPRA goals includ-
ing those related to clean air, clean water, and
safe waste management.
Mercury Research Strategy
Research Areas
Transport, Transformation, and Fate
Risk Management for Combustion Sources
Risk Management for Non-Combustion
Sources
Human Health Effects and Exposure
Ecological Effects and Exposure
Risk Communication
Setting Research Priorities
The MJ& was developed by a group of EPA scientists and engineers representing ORD and the
Agency's Program Offices and Regions. To draft the strategy, the group was divided into eight writing
teams focusing on a number of different aspects of mercury and methylmercury risk assessment and
risk management. The teams consulted a number of documents and individuals in preparing the MRS",
the most influential was the Mercury Study Report to Congress which identified research needs across
a number of areas. The writing teams developed six scientific questions formed around the research
needs identified in the Report to Congress and from other sources, including the Agency's Mercury
Task Force (MTF).
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The writing teams established the research needs for each of the six key scientific questions. The MTF
assisted in this effort by identifying the regulatory and voluntary drivers for mercury and methylmer-
cury facing the Agency over the next five years. The writing teams integrated relevant international
research issues into each research area. Research needs under each key scientific question were
prioritized using three criteria. These criteria were: (1) provides timely scientific information and data
needed to inform current and future Agency decisions on mercury, (2) fills data and information gaps on
mercury not addressed by other organizations, and (3) supports the goals and objectives of ORD's
Strategic Plan and research on risk assessment and risk management. Finally, an expert panel often
external peer reviewers offered their individual and collective opinions of the draft Mercury Research
Strategy and its priorities in December of 1999. Many of the recommendations made by the peer panel
have been incorporated into this final version of the MRS.
Every attempt was made by the writing teams to strike a balance in terms of priorities across the six key
scientific questions. The priorities described in the MRSwQ only a snapshot in time and may well
require adjustment in the coming five years. Priorities can change depending on a number of factors
including: progress in answering the key scientific questions, changes in regulatory deadlines, and
research contributions by other organizations. These factors require that priorities and resource
allocations be revisited on a year-to-year basis and that flexibility be a guiding principle in the annual
budgeting process for the mercury research program.
In the near term, ORD plans to focus on combustion risk management. In the longer term, ORD will
emphasize research that enhances the fundamental understanding of: non-combustion risk manage-
ment, ecological effects and exposure, human health effects and exposure, and risk communication.
Mercury fate and transport research will be a focus throughout the five-year time frame of the MRS.
The Mercury Research Strategy is aligned with current EPA Program Office and Regional priorities and
emphasizes mercury sources resulting from human activities in the United States. It does, however,
recognize the global nature of the mercury problem and the need for addressing impacts in the United
States from emissions generated by other nations. The Mercury Research Strategy is designed to be
flexible and can accommodate redirections as a result of changing Agency priorities and perspectives.
TRANSPORT, TRANSFORMATION AND FATE RESEARCH AREA
Key Scientific Question
How much methylmercury in fish consumed by the U.S. population is contributed by U.S. emissions
relative to other sources of mercury (such as natural sources, emissions from sources in other
countries, and re-emissions from the global pool); how much and over what time period, will levels of
methylmercury in fish in the U.S. decrease due to reductions in environmental releases from U.S.
sources?
Prioritized Research Needs
• Improved understanding of the transport, transformation, and fate of mercury in the atmosphere
• Enhanced monitoring of atmospheric mercury deposition for model application
• Improved understanding of the transport, transformation, and fate of mercury in the aquatic and
terrestrial media
• Enhanced monitoring of mercury and methylmercury in the aquatic and terrestrial media for improved
risk management
Research on transport, transformation, and fate is highly supported throughout the life of the Mercury
Research Strategy. Research needs in this area will take some time to fully address because the
transport, transformation, and fate of mercury is so complex once it enters the environment. This
research will allow for an improved understanding of mercury in air and water, and on land. As funda-
mental understanding is improved, this research will inform the development of more cost-effective risk
management approaches for mercury and methylmercury.
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RISK MANAGEMENT FOR COMBUSTION SOURCES RESEARCH AREA
Key Scientific Question
How much can mercury emissions from coal-fired utility boilers and other combustion systems be
reduced with innovative mercury and multi-pollutant control technologies; what is the relative
performance and cost of these new approaches compared to currently available technologies?
Prioritized Research Needs
• Improved understanding of managing mercury species in combustion processes
• Improved understanding of performance and cost of mercury emissions controls
• Increased testing and evaluation of mercury continuous emission monitors
• Improved characterization of, and management approaches for, mercury controls residuals
Research to manage risks from combustion sources addresses the most immediate mercury priority for
the Agency and is highly supported during the first years of the Mercury Research Strategy.
Combustion risk management research, including research on mercury in controls residuals, will provide
the Agency with the latest information on control technology performance and cost. This research will
result in data and information that informs the preparation of a regulatory proposal for controlling
mercury emissions from coal-fired utilities.
RISK MANAGEMENT FOR NON-COMBUSTION SOURCES
RESEARCH
Key Scientific Question
What is the magnitude of contributions of mercury releases from non-combustion sources; how can
the most significant releases be minimized?
Prioritized Research Needs
• Characterization of the mercury life cycle in human activities
• Improved understanding of mercury releases from sources and sinks
• Approaches for minimizing mercury releases from non-combustion sources
Research to manage risks from non-combustion sources is modestly supported in the early years of the
Mercury Research Strategy. Work in this area then increases as the need for risk management research
on coal-fired utilities declines and other sources of mercury releases come to the fore. Initial activities
will focus on characterizing sources and identifying alternatives to mercury-containing waste incinera-
tion. Work in later years will address pollution prevention, source control, stockpile retirement, and
remediation of contaminated media. With thorough source characterization, this research will focus on
mercury sources posing the greatest risks to both humans and wildlife. This research will provide
information to support future assessments, rulemaking, and voluntary actions across the Agency.
ECOLOGICAL EFFECTS AND EXPOSURE RESEARCH
Key Scientific Question
What are the risks associated with methylmercury exposure to wildlife species and other significant
ecological receptors?
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Prioritized Research Needs
• Improved understanding of methylmercury toxicity effects on avian and mammalian wildlife
• Refined ecological assessments for avian and mammalian wildlife risks
• Improved understanding of ecological impacts of methylmercury on avian and mammalian wildlife
• Improved understanding of ecological impacts of methylmercury on non-avian and non-mammalian
species
• Identification of interactions among methylmercury with other chemical and non-chemical stressors
on all ecological receptors
The effects of methylmercury on ecological systems have been demonstrated, but there is a need to
learn more about these effects, particularly with respect to fish-eating wildlife. Support for this research
area gradually increases over the life of the Mercury Research Strategy. This research will assist the
Agency in understanding the effects and exposures of mercury and methylmercury on birds, fur-
bearing mammals, and other forms of animal life. This research will also assist in the development of
improved ecological assessments.
HUMAN HEALTH EFFECTS AND EXPOSURE RESEARCH
Key Scientific Question
What critical changes in human health are associated with exposure to environmental sources of
methylmercury in the most susceptible human population; how much methylmercury are humans
exposed to, particularly women of child-bearing age and children among highly-exposed population
groups; what is the magnitude of uncertainty and variability of mercury and methylmercury
toxicokinetics in children?
Prioritized Research Needs
• Improved understanding of mechanisms of developmental neurotoxicity from methylmercury
• Improved understanding of persistent and delayed neurotoxicity resulting from developmental
exposures to methylmercury
• Identification of impacts from aggregate exposures and synergistic effects of methylmercury and
other pollutants
• Improved understanding of the modulation of immune system response from methylmercury
exposure
• Improved understanding of the effects on cardiovascular function as a result of methylmercury
exposure
• Biological monitoring for model development and improvement
• Development of toxicokinetic data on methylmercury tissue distribution
The National Academy of Sciences (NAS) report on the health effects of methylmercury supported
EPA's reference dose (RfD) of 0.1 micrograms per kilogram body weight per day as a scientifically-
justified level to protect human health. There remain, however, questions that need to be answered.
Research in this area is supported at a relatively modest, but consistent, level throughout the life of the
Mercury Research Strategy. There is a continuing need for ORD to provide scientific and technical
assistance to the Agency in developing regulations and criteria based on the NAS-supported RfD.
RISKCOMMUNICATIONRESEARCH
Key Scientific Question
What are the most effective means for informing susceptible populations of the health risks posed by
mercury and methylmercury contamination offish and seafood?
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Prioritized Research Needs
• Synchronization of fish consumption advisory messages for methylmercury
• Improved understanding of exposure patterns in targeting of risk messages
• Understanding the use of risk information in making decisions about methylmercury exposures
Research on improved communication to populations at risk from eating fish contaminated with
methylmercury is supported at a relatively modest, but consistent, level over the life of the Mercury
Research Strategy. Research in this area will help the Agency in developing improved risk communica-
tion approaches targeted at populations that consume large quantities of fish. One of the most
challenging populations will be those individuals at greater risk due to possible nervous system
damage such as the maternal-fetal pair, nursing mother-infant pair, and young children. This research
area as one that is particularly amenable to collaborations with other organizations.
MERCURYRESEARCH STRATEGYIMPLEMENTATION
A number of groups, both internal and external to EPA, have a stake in the Mercury Research Strategy
and its implementation over the next five years. These groups are particularly interested in research
program sequencing and timing in order to determine whether they are consistent with their needs,
interests, and with Agency target dates for regulatory and voluntary actions. The MRS'v& designed to
provide broad strategic directions for ORD's mercury research program, not schedules and time lines.
More specific information will be forthcoming in ORD's multi-year implementation plan to be developed
in FY 2001.
The Mercury Research Strategy encourages engagement and partnering with various stakeholders.
ORD believes that joint ventures enhance the Agency's own mercury research program, as well as other
mercury research efforts either planned or underway in the United States. It wants to strengthen
research collaborations with the regulated community and other interested entities and gain their
participation in mutually beneficial mercury research. ORD is seeking linkages to federal agencies,
States, communities, tribes, and other public and private organizations in order to gather insights from
decision makers at various levels. Of particular interest are their mercury research needs and the
actions they expect to take in both assessing and managing mercury risks. ORD welcomes input from
any organization concerning the Mercury Research Strategy and the mercury research program
described herein.
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1.0 INTRODUCTION
1.1 BACKGROUND
Mercury is a naturally occurring element that is neither
created nor destroyed. It enters the environment as a
result of natural (e.g., volcanos, fires, surface emissions)
and human (e.g., combustion, commercial products)
activities (i.e. anthropogenic sources). Depending on the
situation, once deposited on land or water mercury can re-
enter the atmosphere. Mercury is found in the environ-
ment as an inorganic (e.g., elemental mercury vapor [Hg°],
gas-phase ionic mercury [Hg+2], particulate-bound mercury
[Hg ]), and in organic forms (e.g., methylmercury). It is
emitted from human activities in the inorganic form1. Over
the years, some mercury compounds have been specifically
developed as pesticides, fungicides, and germicides to be
used on grains, in paints, and with vaccines.
The amount of mercury released into the biosphere has
increased since the beginning of the industrial age.
Mercury in the atmosphere can be transported
thousands of miles from sources of emission and can
circulate in the atmosphere for up to a year. Most of
the mercury in water, soil, sediments, or plants and
animals is in the form of inorganic mercury salts and
organic mercury (e.g., methylmercury). The inorganic
form of mercury, when either bound to airborne
particles or in a gaseous form, is readily removed from
the atmosphere by precipitation and is also dry
deposited. As it cycles among the atmosphere, land,
and water, mercury undergoes a series of complex
chemical and physical transformations, many of which
are not completely understood.
Excerpt from the Executive Summary of the Mercury
Study Report to Congress, Volume 1, December 1997
(EPA, 1997a).
Mercury and its compounds are persistent,
bioaccumulative and toxic, and they pose human and
ecosystem risks. The intentional use of mercury in
products (e.g., batteries, paints) has decreased signifi-
cantly in the past twenty years (Sznopoek and Goonan,
2000). Since the 19th Century, however, the total amount of
mercury in the environment has increased by a factor of
two to five above pre-industrial levels (Mason, et. al, 1994).
As the quantity of available mercury in the environment
has increased, so too have the risks of neurological and
reproductive problems for humans and wildlife. This makes
mercury a pollutant of increasing environmental concern in
the United States, and throughout the world.
The 1997 Mercury Study Report to Congress improved
EPA's understanding of mercury and its impacts. The
Agency prepared the Mercury Study Report to Congress
in response to Title III, section 112 (n)( 1 )(B) of the Clean
Air Act Amendments (CAA) of 1990 (U.S. Congress, 1990).
In that legislation, Congress directed EPA's Administrator
to conduct"... a study of mercury emissions from electric
utility steam generating units, municipal waste combustion
units, and other sources, including area sources." As part
of the study, the Agency was asked to consider mercury
emissions: (1) rate and mass, (2) health and environmental
effects, and (3) control technologies, including the costs of
such technologies. In carrying out the study, EPA modeled
the emissions of major anthropogenic sources in the
United States and concluded that there was "... a plausible
link between anthropogenic releases2 of mercury from
industrial and combustion sources in the United States and
methylmercury in fish"(EPA, 1997a). The Mercury'Study
Report to Congress also concluded that the fish ingestion
exposure pathway was the route of greatest interest for
stack-emitted mercury. As part of the report, EPA con-
ducted a quantitative human health risk assessment of
methylmercury based on fish consumption surveys. This
risk assessment estimated that between one and three
percent of women of childbearing age (i.e. between the
ages of 15 and 44 years ) eat sufficient amounts of fish for
their fetuses to be at risk from methylmercury exposure.
In addition to the Mercury Study Report to Congress, a
number of other EPA documents have demonstrated the
need for the Mercury Research Strategy. For example, the
Clean Water Action Plan (EPA, 1998a) includes a goal to
improve assurance that fish and shellfish are safe to eat,
and specifically calls for action on mercury. The Study of
Hazardous Air Pollutant Emissions from Electric Utility
Steam Generating Units - Final Report to Congress (EPA,
1998b) identifies hazardous air pollutant emissions from
utility boilers. The report indicates that of the pollutants
studied, on balance, mercury releases from coal-fired power
plants are the greatest potential public health concern. The
Deposition of Air Pollutants to the Great Waters: Third
Report to Congress (EPA, 2000a) lists mercury among the
15 Great Waters "Pollutants of Concern." Finally, the EPA
Program Offices and Regions, via the Mercury Task Force
(MTF), have prepared the Draft EPA Action Plan for
Mercury as part of A Multimedia Strategy for Priority
Persistent, Bioaccumulative, and Toxic Pollutants
(Federal Register, 1998). Afinalplan, which includes a
number of near-term and longer-term regulatory and
voluntary actions that EPA will undertake to address
mercury, is expected in late-2000.
ORD developed the Mercury Research Strategy in close
consultation with EPA's Program and Regional Offices and
will use it to guide the development of a more detailed
multi-year implementation plan in F Y 2001. The MRS
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provides strategic guidance for ORD's mercury research
program over the next five years (FY2001 - 2005). It is
specifically designed to target both near-term and long-
term scientific research needs. In the near term, ORD plans
to focus on combustion risk management. In the longer
term, ORD will emphasize research that enhances the
fundamental understanding of human health effects and
exposure, ecological effects and exposure, non-combustion
risk management, and risk communication. Mercury fate
and transport research will be a focus throughout the five-
year time frame of the MRS. The Mercury Research
Strategy recognizes the global nature of the mercury
problem and the need for addressing impacts in the United
States via hemispheric transport of emissions generated by
other nations. Its emphasis, however, is on domestic
sources. This is in accordance with existing EPA program
priorities, although priorities can change as a result of
changing Agency needs.
The goal of the MRS"wi\\ be accomplished through an
applied in-house research program conducted by ORD
laboratories and assessment center. Coupled with these in-
house efforts, ORD's Science to Achieve Results (STAR)
Grants Program conducted by the National Center for
Environmental Research (NCER) will sponsor extramural
research. This research will advance the fundamental
understanding of important mercury and methylmercury
issues. Other organizations will also be invited to address
pertinent scientific and technical topics in their areas of
competency. The research conducted under the MRS"wi\\
be multi-disciplinary in nature, requiring engagement and
collaboration across a host of different scientific and
technical disciplines. Results from the mercury research
program will provide the scientific underpinnings for any
actions (e.g., voluntary, regulatory) that the Agency
chooses to pursue in the future to address mercury risks.
1.1.1 Exposure Route of Most Concern
The J^Wincorporates a number of the research needs
identified in the Mercury Study Report to Congress and
emphasizes the route of exposure portrayed in Figure 1.
That exposure route begins when mercury is emitted from
human activities (i.e., anthropogenic sources) and becomes
airborne for varying periods of time. Eventually, airborne
mercury is deposited on land or water where it is trans-
formed to organic forms of mercury (i.e., methylmercury3).
This methylmercury is taken up by fish and fish eaters
(e.g., larger fish, eagles, otters) and eventually can find its
way into humans. Once in humans at high enough
concentrations, methylmercury causes neurological
damage and is particularly harmful to developing fetuses
and young children (i.e., under 6 years of age).
While the Mercury Research Strategy emphasizes the fish
ingestion exposure pathway, it is not the only one of
interest to the Agency. Inhalation is another exposure
pathway of interest, but is not addressed in the MRS. A
national multi-agency task force is looking at the ritualistic
use of mercury4. While the AffiS'does not focus on
ritualistic use, ORD intends to work with the task force on
this route of exposure, and as appropriate, will work with
other Agencies and organizations on other mercury
exposure routes posing human and ecological risks.
The mercury transformations that occur in air, water, and on
land and methylmercury's accumulation in fish, wildlife,
and humans (based on the fish ingestion exposure
pathway) present a set of scientific and technical chal-
lenges for both Agency regulators and researchers. With
respect to mercury research, some of the challenges
include, but certainly are not limited to, developing
methods that accurately characterize mercury sources and
Figure 1. Mercury Fish Ingestion Exposure Pathway, the Focus of the Mercury Research Strategy.
2
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the species of mercury released from those sources;
understanding mercury transport and the transformations
that occur in the air and water and on land; assessing
mercury exposures to and effects on humans and ecosys-
tems; and developing cost-effective ways to manage risks
from mercury sources and sinks5. All of these challenges
are addressed in the MRS.
1.2 EVTERNAT1ONALNEEDTO
ADDRESS MERCURY
Mercury is recognized internationally as an important
pollutant warranting collaborative study and action.
Virtually all countries have a common interest in mercury,
since they are mercury exporters and importers via atmo-
spheric transport. Domestic mercury reductions are only
one component, albeit a very important one, for managing
mercury risks in the United States. Another component is
a better technical understanding of global mercury sources
and circulation patterns, as well as improved estimates of
global contributions to domestic ambient mercury levels.
To successfully influence changes in mercury use and
emissions abroad, the United States must share mercury
control technology and engage in international risk
management activities addressing mercury reductions. The
rapid industrialization of China and other Asian nations
and the resulting increased role of coal in those countries
suggest an increasing emphasis on protecting the United
States from international mercury sources.
Attention to monitoring and modeling (including specia-
tion) along all U.S. borders for transboundary transport
(both entering and exiting) and deposition of mercury are
priorities. Preliminary studies suggest that:
• air masses from Asia reach the west coast of the United
States in 3-4 days (Jaffe, et al., 1999);
• the Arctic receives 33 percent of its heavy metals
deposition from industrial sources in Europe and
North America (AM AP, 1997);
• trans-Atlantic transport could bring mercury species to
South Florida as a consequence of dust storms in the
Sahara Desert (Landis, et al., 2000).
• mercury transits to and from the United States, Canada,
and Mexico (Nriagu, 1999).
EPA's long-range modeling analysis of domestic anthropo-
genic sources, as reported in the Mercury Study Report to
Congress, found that there is no region of the United
States where mercury deposition is not occurring. The
range of deposition spans two orders of magnitude (0.5 - 50
ug per square meter per year) (EPA, 1997a). EPAisjust
beginning to focus on the regional, intercontinental, and
global dimensions of mercury. One team of investigators
has estimated that Asian sources account for about 46
percent of the anthropogenic mercury global total (Pirrone,
et al., 1996). While combustion sources are a significant
concern, there are uncertainties in the understanding of
mercury emissions from non-combustion sources such as
mercury cell chlor-alkali facilities. Globally, 200-300
factories hold approximately 50-60 million pounds of
mercury and require 2-3 million pounds of new mercury
annually to replenish consumption during production
(Anscombe, 2000).
There is a growing appreciation of the global nature of the
mercury problem and also of the need for joint action. EPA
is currently exploring, with the Department of State (DOS),
a variety of mechanisms and activities to elevate attention
to mercury internationally. As a foundation for an interna-
tional focus, the Agency now plans to develop an Interna-
tional Mercury Strategy. This international strategy will
provide a framework and rationale for guiding the
Agency's efforts, in concert with other agencies and the
international community. It will facilitate development of
global coordination and action on risk assessment and risk
management for mercury. The international strategy will
address how best to: (1) obtain and apply international
routine emissions (including speciation) and multimedia
monitoring and modeling information; (2) obtain and apply
international research on exposure, effects, ecological and
human risk assessment, and risk management research
information; and (3) develop and implement risk manage-
ment objectives in pollution prevention, capacity building,
training, technology transfer and international formal
deliberations, such as treaties or other mechanisms.
1.3 MERCURYRESEARCH
STRATEGYORGANIZAnON
The MRS addresses a range of topics, including sources of
mercury releases, air emission sources, human health and
wildlife impacts, transport and fate of mercury in the
environment, and techniques to manage risks from the
largest emitting sources. It is organized as follows:
• Chapter 2.0 describes the challenges associated with
mercury from source to receptor, including a discussion
of mercury emissions and releases; mercury transport,
transformation and fate; impacts of methylmercury on
human and wildlife health; and mercury and methylmer-
cury risk management.
• Chapter 3.0 explains why the MJfS"was developed and
includes: the findings of the National Academy of
Sciences (NAS) on the methylmercury reference dose
(RfD); regulatory commitments on mercury by Agency
Programs; voluntary efforts to prevent or minimize
mercury in products, processes and wastes; and
international opportunities to reduce mercury on a
global scale.
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Chapter 4.0 summarizes the research efforts being
performed by public and private organizations (e.g.
federal, state, and local governments; academic institu-
tions; the private sector) as well as international
research efforts that will complement the research areas
discussed in the MRS.
Chapter 5.0 presents the key scientific questions and
the strategic directions for EPA's mercury research
program over the next five years, and identifies EPA's
research priorities. It also provides detailed descrip-
tions of the research needs to be addressed under each
of the six key scientific questions.
Chapter 6.0 identifies issues beyond research that
deserve attention and are supportive of the Mercury
Research Strategy. It also describes future opportuni-
ties for engagement and partnering with a variety of
stakeholders (e.g., regulated entities, environmental
groups, community decision-makers at all levels, the
general public, international entities).
Chapter 7.0 contains the set of references cited in the
Mercury Research Strategy.
Appendix A includes a summary of nine transport and
fate grants awarded in FY1999 as part of ORD's STAR
Grants Program.
1. The Mercury Study Report to Congress identified methylm-
ercury as the mercury chemical species of greatest environ-
mental concern. Volume V of the Mercury Study Report to
Congress and the toxicology profile on mercury developed by
the Agency for Toxic Substances and Disease Registry
(ATSDR, 1999) provide more information on the adverse
human health effects of inorganic mercury.
2. For the purposes of the Mercury Research Strategy,
releases include all forms of mercury entering the environ-
ment (i.e., air, water, deposited on land). The term emissions
deals with mercury entering the air. The term effluents deals
with waterborne mercury entering water or depositing on land.
3. For the purposes of the Mercury Research Strategy,
"mercury" refers to all forms of the element prior to methyla-
tion. Adverse human and ecological effects of the element
occur from methylmercury exposures reflecting the chemical
species bioconcentrated in the aquatic food web. Conse-
quently, the term "methylmercury" is used when describing
mercury in fish and the adverse health effects of mercury via
the fish ingestion exposure pathway. When describing
Agency programs, efforts, and documents the generic term
"mercury" is used for all chemical species of mercury.
4. The task force is co-led by EPA's Office of Emergency and
Remedial Response (OERR) and the Agency for Toxic
Substances and Disease Registry (ATSDR). In the near term,
the task force plans to convene an external expert panel to
address the issue of ritualistic use, develop a tool kit to help
local and state governments respond to ritualistic use
problems, sponsor a pilot investigation to better understand
the scope and nature of the exposure and prepare a national
strategy on how to deal with the issue of ritualistic use.
5. For the purposes of the Mercury Research Strategy,
sources are generally locations (e.g., points, areas) of
mercury releases, including emissions, from human activities
and sinks are locations of mercury deposition. It is recog-
nized that sources may also be natural mercury sources and
sources that re-emitted mercury. In some cases, sinks may
act as re-emission sources, depending upon their location and
the form of the mercury present in the sink.
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2.0 PROBLEM DESCRIPTION
2.1 WHYMERCURYPOSESARISK
The amount of mercury released from both natural and
anthropogenic sources is difficult to quantify. Studies by
Nriagu and Pacyna (1988) estimated global natural emis-
sions at 3000 tons per year and the median for global
emissions from human activities at 3560 tons per year (1983
basis). A more recent critical review by Jackson (1997)
estimated that 2000 tons of mercury are emitted each year
from natural sources, while 4000 tons of mercury are
emitted each year from sources attributed to human
activities (e.g., combustion of fossil fuel and solid waste).
An overview of global atmospheric emissions prepared by
Schroeder and Munthe (1998) cited a number of other
natural and anthropogenic source estimates along with the
scientific uncertainties associated with estimates for both.
When airborne mercury is deposited on land or in water,
biological transformations can occur that yield methylmer-
cury. In its methylated form, mercury accumulates most
efficiently in the aquatic food web resulting in risks to both
humans and ecosystems (EPA, 1997a). Nearly all of the
mercury that accumulates in fish is methylmercury. In
lakes, rivers, and reservoirs, methylmercury is taken up by
fish, resulting in significant increases in its concentration
in fish tissue (i.e., bioaccumulation). In some instances,
the concentrations of methylmercury in fish may be several
orders of magnitude greater than the concentrations in the
surrounding water or sediment. Inorganic mercury, which
is less efficiently absorbed and more readily eliminated
from the body than methylmercury, tends not to
bioaccumulate.
Human and wildlife exposure to methylmercury occurs
almost exclusively through fish consumption. Fish eaters
at the top of the aquatic food web generally exhibit higher
methylmercury concentrations than those lower in the food
web. The decision to focus on this exposure pathway in
the Mercury Research Strategy is supported by modeling
results from the Mercury Study Report to Congress
(Volume IV: An Assessment of Exposure to Mercury in the
United States). That modeling effort demonstrated that
fish consumption poses the greatest risks to human health
and wildlife. The impacts from urban and agricultural
modeling were not of a comparable concern.
2.2 IMPACTS OF METHYLMERCURY
ON HUMAN HEALTH AND
WILDLIFE
Methylmercury is known to have toxic effects in humans,
causing permanent damage to the brain and kidneys. The
developing nervous system (e.g., human fetuses, bird
embryos) is particularly sensitive to methylmercury
exposures. Human epidemics of methylmercury poisoning
(e.g., Japan, Iraq) have established its toxicity to the
nervous system (EPA, 1997a).
There are extensive data on the effects of methylmercury
on the development of the brain (neurodevelopmental
effects) in humans and animals. The most severe effects
reported in humans were seen following high dose
poisoning episodes in Japan and Iraq. Effects included
mental retardation, cerebral palsy, deafness, blindness and
dysarthria in individuals who were exposed in utero and
sensory and motor impairment in exposed adults.
Chronic, low-dose prenatal methylmercury exposure from
maternal consumption of fish has been associated with
more subtle end points of neurotoxicity in children.
Those end points include poor performance on
neurobehavioral tests, particularly on tests of attention,
fine-motor function, language, visual-spatial abilities (e.g.,
drawing), and verbal memory.
Excerpt from the Executive Summary of the Toxico-
logical Effects of Methylmercury, National Research
Council 2000. http://books.nap.edu/books/
0309071402/html/index.html
2.2.1 Human Health Impacts
Perhaps the most well known incident of mercury poison-
ing involved the consumption of methylmercury-contami-
nated seafood from Minamata Bay in Japan during the
1950s. In that case, mercury was used as a catalyst in an
acetaldehyde production plant and was released into the
Bay. The methylmercury poisoning involved the death and
permanent disability of a number of individuals. The
pathway of exposure being addressed in the Mercury
Research Strategy is far more subtle. It involves the
emission of low concentrations of mercury, mainly from
combustion sources. These emissions lead to the build-up
of methylmercury in water bodies and fish tissue over time.
It is important to stress that the most likely individuals
being exposed to a high level of methylmercury are
consumers of large quantities of fish (e.g., subsistence
fishers). Pregnant women (maternal/fetal pair) and young
children are particularly sensitive to exposures of high
levels of mercury.
As illustrated in Figure 2, forty states have some form of
mercury fish advisories for their water bodies. Statewide
advisories for mercury occur consistently across the
Northeastern states; Gulf Coast states have advisories in
all coastal waters. In Canada, 97 percent offish advisories
are attributable to mercury. Mercury is the major reason for
fish advisories, and there is an increasing trend in the
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I States Have No Mercury Advisory Program
States Meeting Search Criteria
;.£S-I Statewide Costal Advisory Included In Counts
Statewide Advisory Included in Counts
Canadian fish advisories reflect total fish advisories during 1997 (2,625).
More than 97% (2,572) were attributable to Mercury.
Provincewide advisories in effect in 1997 for Nova Scotia
(all rivers and lakes) and New Brunswick (all lakes).
Figure 2. Mercury-based Fish Consumption Advisories for North America (EPA, 1999a; EPA, 1999c).
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number of advisories due to its presence in the nation's
waters. Based on an analysis of dietary surveys, the
Mercury Study Report to Congress (EPA, 1997a) risk
assessment concluded that typical fish consumers in the
United States were not in danger of ingesting harmful
levels of methylmercury. This is a reflection of the rela-
tively low amounts offish consumed by the typical U.S.
citizen.
Based on the same analysis of United States dietary survey
data, the risk assessment estimated the percentage of
people from different populations who consume methylm-
ercury in excess of the Reference Dose (RfD)(EPA, 1997a)'.
Among white/non-Hispanic populations, the fraction
above the RfD was 9.0 percent, among black/non-Hispan-
ics, 12.7 percent, and among persons of Asian/Pacific
Islander ethnicity, Native American tribal members, and
non-Mexican Hispanics (e.g., persons from Puerto Rico and
other Caribbean islands), 16.6 percent. Among women of
childbearing age (i.e., 15 through 44 years), 7 percent of the
more than 58 million women in the group (i.e., more than 4
million women) are exposed to methylmercury from fish at
levels in excess of the RfD, using month-long exposures as
the basis for calculation.
Depending on the methylmercury concentration in the fish,
women may be putting their fetuses at risk to the subtle
neurological and developmental effects associated with
methylmercury exposure. In addition to women of child-
bearing age and their fetuses, populations of concern
include young children (whose nervous systems continue
to develop after birth). Young children exposed to methyl-
mercury are of particular concern (EPA, 1997a), especially
when they are members of a group who depend heavily on
fish and fish-eating mammals as part of their diets (e.g.,
some native groups that are subsistence fishers).
2.2.2 Wildlife Impacts
Concentrations of mercury in the tissues of wildlife
species have been reported at levels associated with
adverse effects in laboratory studies of the same species.
However, field data are insufficient to conclude whether
piscivorous wading birds or mammals have suffered
adverse effects due to airborne mercury emissions.
Modeling analyses suggest that it is probable that
individuals of some highly exposed wildlife sub-
population are experiencing adverse effects due to
airborne mercury.
Excerpt from the Executive Summary of the Mercury
Study Report to Congress, Volume I, December 1997.
http://www.epa.gov/oar/mercurv.htm
The impacts on wildlife from exposures to methylmercury
are described in detail in the Mercury Study Report to
Congress (EPA, 1997a). For purposes of this discussion,
wildlife includes fish, birds (e.g., loons, ducks, eagles), and
fur-bearing mammals (e.g., otters, mink, panthers). All are
susceptible to adverse methylmercury health effects.
Marine mammals such as seals, walruses, dolphins and
whales are also susceptible to methylmercury. Trace levels
of mercury have been found in the liver of seals, porpoises
and dolphins (Law, et al., 1991). The exposure pathway in
aquatic systems indicates that birds and small mammals
that feed primarily on fish and those that prey on these fish
eaters will be at the greatest risk of toxic effects from
methyl-mercury. An important aspect of these effects are
the bioaccumulation of methylmercury by less complex
organisms (e.g., plankton, clams, crayfish,) and then their
consumption by fish and small mammals. Direct uptake of
methylmercury in the water column is also a pathway of
exposure. These species can actually provide an early
warning of mercury contamination via indications of
neurological damage and reduced reproductive levels.
Mercury toxicity in fish is variable depending on a number
of factors. These include fish characteristics (e.g., species,
life stage, age, size), environmental factors (e.g., tempera-
ture, salinity, dissolved oxygen content, water hardness,
other chemicals), and the form of mercury available (EPA,
1997a). The effects of methylmercury on early life stages of
fish present more acute problems such as death, reduced
reproduction, impaired growth and development, behav-
ioral abnormalities, altered blood chemistry, reduced
feeding rates and predatory success, and effects on
oxygen exchange. Some signs of acute mercury poisoning
include increased mucous secretion and respiration rate,
loss of equilibrium, and sluggishness. Chronic poisoning
is represented by emaciation, brain lesions, cataracts, and
an inability to capture food. Evidence suggests that
effects can be detected in water concentrations between
0.1 and 1.0 micrograms per liter for some species.
As summarized in the Mercury Study Report to Congress
(EPA, 1997a), symptoms of mercury poisoning in birds
include: muscular incoordination, falling, slowness, fluffed
feathers, calmness, withdrawal, hyperactivity, hypoactivity,
and drooping eyelids. Liver and kidney damage,
neurobehavioral effects, reduced food consumption,
weight loss, spinal cord damage, enzyme system effects,
reduced cardiovascular function, and impaired growth and
development are several of the indicators of sublethal
effects of mercury in birds. Tissue mercury concentrations
that are associated with toxicity in birds are similar despite
differences in species, dietary exposure level, and length of
time necessary to produce the effect. Neurological signs
are generally associated with brain mercury concentrations
of 15 micrograms per gram (wet weight) and 30 micrograms
per gram in the liver and kidneys. With respect to
hatchlings, mortality was observed in ducklings at 3 to 7
micrograms per gram (wet weight), at 2 to 3 micrograms per
gram in loon eggs, and at 3.6 micrograms per gram in tern
eggs. No effects were seen in herring gull hatchlings
although the eggs contained approximately 10 micrograms
per gram of mercury.
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The Mercury Study Report to Congress identified the mink
and otter as examples of fur-bearing mammals with in-
creased risk from methylmercury exposure (EPA, 1997a).
This was for exposures related to direct discharges of
mercury to water bodies. The impacts of mercury on these
mammals are less clear than for either fish or birds. This
may be a direct reflection of the limited number of studies
conducted on fur-bearing mammals and, in some cases, the
confounding effects of other stressors. These stressors,
cited for the endangered Florida panther, include habitat
fragmentation, inbreeding, and feminization by endocrine
disrupting compounds. With respect to the Florida panther,
relatively high levels of mercury (0.005 to 20.0 micrograms
per gram) have been measured in archived liver samples of
dead animals. In another case, one death was attributed to
mercury poisoning with mercury measured at 100 micro-
grams per gram in the liver and 130 micrograms per gram in
the hair.
Based on the investigations reported in the Mercury Study
Report to Congress (E?K, 1997a), causal links with airborne
mercury deposition have not been established, but may
contribute to population effects in some birds and fur-
bearing animals, including the Florida Panther. The effect
of mercury from point sources on limited wildlife popula-
tions, however, has been demonstrated. Tissue residues
from these studies provide a basis for evaluating risks to
other wildlife populations. Overall, wildlife (e.g., fish, birds,
fur-bearing mammals) appear to be more susceptible to
mercury effects when they are located in ecosystems that
experience the following: (1) high levels of atmospheric
deposition, (2) surface waters already impacted by acid
deposition, (3) characteristics other than low pH that result
in high levels of mercury bioaccumulation in aquatic biota,
and (4) species that experience high levels of exposure.
2.3 MERCURYUSES AND RELEASES
2.3.1 Uses
Mercury has been widely used in industrial applications
because of its unique properties. It conducts electricity,
responds to temperature and pressure changes, and forms
alloys with almost all metals. In the electrical industry,
mercury is used in fluorescent lamps, as part of wiring
devices, and with instruments that measure temperature
and pressure. It is also a component of dental amalgams
used in restoring teeth. In addition to its use in specific
products, mercury is used in numerous industrial pro-
cesses. The largest manufacturing use of mercury in the
United States is associated with the production of chlorine
and caustic soda by mercury-cell chlor-alkali plants.
Mercury is also used in amalgamation with other metals
(e.g., gold) and as an antifungal agent in wood preserving
(EPA,1997a).
2.3.2 Releases
The most significant releases of mercury to the environ-
ment in the United States are emissions to the atmosphere.
These emissions can be characterized as releases by
human activities (i.e., anthropogenic), releases from
geologically bound mercury through natural processes,
and releases through mass transfer to the atmosphere by
biologic and geologic processes from previously deposited
mercury (i.e., re-emitted) (EPA, 1997a)2. The Mercury Study
Report to Congress presents an inventory (based on 19947
1995 data) of anthropogenic mercury air emissions in the
United States (See Table 1). This table presents the
percentage of anthropogenic emissions attributable to each
major source.
Table 1. Summary of Major Sources of Anthropogenic
Mercury Air Emissions (EPA, 1997a).
Source Percent
Coal-fired electric utility boilers 32
Municipal waste combustors 18
Coal- and oil-fired commercial/industrial boilers 18
Medical waste incinerators 10
Chlor-alkali plants 4
Portland cement plants 3
Oil-fired residential boilers 2
Other sources of mercury 13
Anthropogenic mercury sources within the United States
emit approximately 158 tons of mercury per year (EPA,
1997a)3. The source categories presented in the table each
constitute more than one percent of the total amount of
mercury emitted to the atmosphere from human activities.
The greatest emissions of anthropogenic mercury to the
environment are from combustion of fuel that contains
trace amounts of mercury. Emissions also come from
industrial processes that use mercury, and disposal
(especially by incineration) of products that contain
mercury either as an intentional constituent or as an
impurity.
Mercury-bearing wastes are generated from manufacturing
processes and the disposal of consumer products. In 1995
an estimated 245 tons of mercury were discarded in
municipal waste streams (EPA, 1997a). Most of this waste
was either incinerated or placed in landfills. Industrial
hazardous wastes with high mercury concentrations are
currently incinerated or retorted. Retorting involves the
heating of mercury-containing wastes with the mercury
converting to a vapor. The mercury vapor is then captured
and condensed back to its metallic form. The intentional
use of mercury in commercial products in the United States
has declined by more than 75 percent from 1988 to 1996
(EPA, 1997a). This reduction is largely due to the private
sector's efforts to eliminate the use of mercury in products
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and processes when replacements can be found. Along
with this commercial use reduction, an increase in the
recycling and recovery of mercury has resulted in a supply
of the metal that now exceeds domestic demand.
In addition to air emissions and land disposal, mercury is
released in other ways, including discharges from industrial
sources and waste sites and releases of methylmercury
from sediments to water bodies. Release of mercury in
water discharges is believed small when compared to
atmospheric emissions, but it can have significant local
effects. Mercury discharges to surface waters from
abandoned gold and mercury mines in the western United
States may well be the cause of fish advisories for meth-
ylmercury in a number of streams and lakes. An example is
the contamination of Clear Lake in California by the
Sulphur Bank Mercury Mine Superfund Site. An interna-
tional example of mercury pollution from an industrial
source exists in Natal, South Africa, where the Thor
Chemical Plant houses large quantities of mercury wastes
that have leaked/leached to the nearby environment and
groundwater. Releases of methylmercury from sediments
have not been well quantified, but high concentrations of
methylmercury in sediments often coincide with high
concentrations of methylmercury in fish tissue (EPA,
1999a).
Modeling conducted as part of the Mercury Study Report
to Congress (EPA, 1997a) estimated that approximately
one-third of the United States anthropogenic mercury
emissions (about 52 tons) are deposited through wet and
dry deposition within the contiguous 48 States. The
remaining two-thirds is transported outside the continental
U.S. and enters the global mercury cycle. It is estimated
that an additional 35 tons per year are deposited in the
United States from the global cycle (i.e., anthropogenic,
natural, and re-emitted sources) (EPA, 1997a). As a
consequence of mercury emission controls on a number of
sources, anthropogenic mercury emissions in the United
States will most likely decline over the next several years.
According to Pirrone, et al., (1996), releases from human
activities globally will increase mercury deposition in the
United States unless reductions also occur in other
countries. The role that emissions from natural and re-
emitted sources play in assessing reductions to mercury is
a complicating factor. These emissions must be taken into
consideration in any estimates or documentation of total
mercury reductions to the environment over the longer
term.
2.4 MERCURYTRANSPORT,
TRANSFORMATION, AND FATE
2.4.1 Transport
The air transport and deposition patterns in the United
States for mercury emissions depend on various factors,
including the form of mercury emitted, the location of the
emissions source, the stack height of the source, the
topography near the source, and the prevailing air circula-
tion patterns. For example, anthropogenic point sources
(e.g., coal-fired electric utility boilers, municipal waste
combustors) emit primarily elemental mercury vapor (Hg°),
gas-phase ionic mercury (Hg+2), and lesser amounts of
particulate-bound mercury (Hgp). The chemical and
physical properties of these different mercury forms
influence their behavior in the environment and their
significance as contaminants that have local, regional and
global scale impacts.
Local scale impacts result from deposition within a 30-mile
radius of an emissions source. For example, a source
emitting primarily Hg+2 can be expected to have a relatively
high percentage of mercury deposited within the 30-mile
radius via wet deposition (EPA, 1997a).
Regional scale impacts result from either wet or dry
deposition associated with long-range transport of
emissions over hundreds of miles dispersed across wide
areas. The highest deposition rates in the United States
are predicted to occur in the southern Great Lakes and
Ohio River Valley, the Northeast and scattered areas in the
Southeastern United States (EPA, 1997a).
Global scale impacts result from Hg° emissions that
become part of the global emissions pool, where they can
remain for a year or more before wet or dry deposition, on
land or water. For example, recent studies indicate that in
Arctic air, elemental mercury vapor may be oxidized
resulting in increased mercury deposition (Schroeder and
Munthe, 1998).
2.4.2 Transformation and Fate
Anthropogenic mercury that is released directly to land or
water bodies, or is deposited on them from the atmosphere,
undergoes transformations that are not fully understood.
These transformations convert some of the mercury to
methylmercury. Not only is methylmercury much more
toxic to humans and wildlife than inorganic mercury, but it
is also more likely to bioaccumulate in fish tissue. This
ability to bioaccumulate results in food chain impacts
yielding higher concentrations of methylmercury in both
humans and wildlife. The amount of mercury transformed
to methylmercury varies greatly from one water body to
another. According to Krabbenhoft, et al., (1999), there are
a number of factors that influence methylmercury produc-
tion beyond mercury loading. These are environmental
setting (e.g., climate, geology, land use, land cover), water
chemistry, and wetland density with the latter being the
most important basin-scale factor controlling methylmer-
cury production.
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2.5 MERCURYAND
METHYLMERCURYRtSK
MANAGEMENT
2.5.1 Risk Management
Reducing risks from methylmercury is difficult because of
the wide variety of sources that contribute mercury to the
environment. Managing emissions and other releases of
mercury requires a variety of approaches ranging from
product substitution to end-of-pipe treatment. Some
actions, such as eliminating mercury used in paints and
batteries and controlling flue gas emissions from municipal
waste combustion units and medical waste incinerators, are
part of the technological options already used to reduce
releases and emissions. Other options, such as removing
mercury-containing products from waste streams (separa-
tion), coal cleaning, fuel switching, advanced mercury
sorbents, sediment remediation methods, substitutes for
mercury used in electronic switches and thermometers, and
conversion of chlor-alkali plants from a mercury electrolytic
cell to a membrane cell process, are available or under
development.
Cooperative research between the public and private
sectors is underway (e.g., coal-fired utilities, mercury chlor-
alkali production) to further develop management options,
test and evaluate innovative solutions, refine or develop
new data on their costs, and determine the benefits of
combining various risk management approaches. Life-cycle
tools are in various stages of development to evaluate how
a mix of options can best be deployed to maximize reduc-
tion of risks to humans and wildlife at minimal cost.
Development and evaluation of process changes, product
substitutions, and innovative technologies will provide
additional ways to address mercury. Finally, as the demand
for mercury continues to decrease, issues involving
mercury retirement will also come to the fore.
An improved understanding of exposure patterns (e.g.,
amount of fish consumed, types of fish consumed,
frequency of consumption) will assist in targeting both
populations and the messages those populations receive.
Research is needed on ways that people, in particular the
populations most exposed to mercury and methylmercury
risks, use information to make informed decisions. This will
be particularly challenging since the most-exposed
populations (i.e., fetuses and young children) are not able
to understand risk messages. The groups to reach will be
their parents and other responsible adults.
1. A reference dose (RfD) is defined as an estimate (with
uncertainty spanning perhaps an order of magnitude) of a
daily exposure to the human population (including sensitive
populations) that is likely to be without an appreciable risk of
deleterious effects during a lifetime. (EPA, 1997a). At the RfD
or below, exposures are expected to be safe. The risk
associated with exposures above the RfD is uncertain, but
risk increases as exposures to methylmercury increase.
2. With respect to this last category, a large portion of the
deposited mercury is the result of past anthropogenic
releases as well as releases from natural sources that
heretofore have been sequestered (e.g., arctic tundra, ice
sheets, oceans and wetlands) (Lindberg, et al., 1998).
3. According to the Mercury Study Report to Congress, "[t]he
current state of knowledge of mercury emissions . . . does not
allow for an accurate assessment of either natural or re-
emitted mercury emissions." It is altogether likely that natural
and re-emitted mercury emissions associated with contami-
nated soils and water bodies within the United States could
add significantly to this value (EPA, 1997a).
2.5.2 Risk Communication
Communicating human health and ecological risks is an
important component of any regulatory or voluntary
Agency action and a vital part of effective risk manage-
ment. Research can contribute to a methylmercury risk
communication program in several ways that will assist
EPA, state and local officials, and the public. There is a
need to synchronize and standardize the fish consumption
advisory messages for the numerous states in which they
are issued. The criteria or standards each state uses to
make fish advisory decisions are an essential element of
any such effort. This research can be facilitated with a
concerted and collaborative effort on the part of the federal
agencies (i.e., EPA, ATSDR, Food and Drug Administration
[FDA]) that set various action levels for methylmercury in
fish.
10
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3.0 REGULATORY ACTIONS AND OTHER FACTORS THAT
INFLUENCE MERCURY RESEARCH PRIORITIES
3.1 NAT1ONALACADEMYOF
SCIENCES REPORT
In the FY1999 conference report for EPA's appropriation
(U.S. House of Representatives, 1998), Congress directed
the Agency to "... enter into a contract... with the
National Academy of Sciences (NAS) to perform a compre-
hensive review of mercury health research...." As part of
that study, NAS was to make recommendations on a
scientifically appropriate reference dose (RfD) for mercury
exposure. Methylmercury was specifically targeted and the
goal was to resolve varying interpretations of methylmer-
cury health effects data. EPA was directed to delay any
decisions to regulate mercury until the NAS findings had
been published. The findings of the NAS study (NRC,
2000) were presented on July 11,2000. They support EPA's
current RfD of 0.1 micrograms per kilogram body weight per
day as a scientifically justified level to protect human
health. The study further affirmed that the fetus is the
most vulnerable to methylmercury effects and that the
developing nervous system is the critical endpoint for risk
calculations.
The NAS report evaluated data on methylmercury effects
from the Seychelles and Faroe Islands studies, as well as
recently published data from a New Zealand study. An
integrative analysis of all three studies was performed and
some of the Faroe Islands study data were extensively re-
analyzed. Using these analyses, NAS recommended that
the data from the Faroe Islands study (rather than the data
from an older Iraqi study) be used as the basis for the RfD
(NRC, 2000). The Iraqi study, involving poisoning through
the consumption of mercury-treated wheat, was used to
establish the EPA RfD in 1994 (EPA, 1997a). The NAS
study also recommended that a safety factor of 10 was
needed to address any scientific uncertainties that
remained. With the NAS study completed and supportive
of the Agency's RfD, EPA is now faced with making
decisions on regulating mercury and methylmercury in the
environment.
3.2 REGULATORY AND OTHER
DOMESTIC COMMITMENTS
Numerous Program Office commitments related to mercury
must be addressed over the next five to ten years (Table 2).
This section presents a brief summary of existing and
proposed regulations and initiatives related to mercury.
The data collected in preparation for rule making or
submitted in compliance with regulatory requirements or
initiatives will help guide the Mercury Research Strategy.
Likewise, the information collected as part of the MRS
research effort will help inform the rule making process.
This exchange of mercury-related information will improve
the Agency's understanding of mercury use in specific
industries, its impact on human health and wildlife, and its
fate and transport. Descriptions of existing and proposed
mercury-related regulations and initiatives are summarized
in Table 2 and described in this section.
3.2.1 Regulatory Activities
Mercury Controls for Utilities: One of the most important
commitments is the Office of Air and Radiation's (OAR's)
implementation of the 1990 Clean Air Act, as amended. As
required by section 112(n) of the Act, EPA is faced with
regulating hazardous air pollutants (HAPs), including
mercury, from coal-fired electric utility steam generating
units. A positive determination means that EPA is required
to propose regulations by December 15,2003 and promul-
gate final regulations by December 15,2004. Full compli-
ance by the utility industry would be expected by Decem-
ber 15,2007. Such a regulatory program requires the
development of technical information and data on the cost
and performance of options (e.g., flue gas treatment, coal
cleaning) to reduce utility boiler emissions.
MACT Rules for Chlorine Production and Municipal
Solid Waste Landfills: Under section 112 of the Clean Air
Act, EPA is required to develop national emission stan-
dards based on maximum achievable control technologies
(MACT) for HAPs (which includes mercury) listed in
section 112 (b) for various source categories such as
chlorine production, municipal landfills, and industrial/
commercial/institutional boilers. Generally, sources are
required to be in full compliance with these rules three
years after promulgation of the final rule.
Chlorine Production - OAR is developing a rule that will
limit mercury emissions from plants that produce chlorine
using the mercury cell method. EPA plans to issue a
proposed rule by November 2000 and a final rule by
November 2001. The rule will be based on best available
control technologies and stringent management practices.
Municipal Solid Waste Landfills - OAR is developing a rule
that will address emissions of HAPs from municipal solid
waste landfills using the MACT approach. EPA plans to
issue a proposed rule by November 2000 and a final rule by
September 2001. This source category includes contigu-
ous geographical space/facilities receiving household
waste, and other types of Resource Conservation and
Recovery Act (RCRA) Subtitle D waste, such as commer-
cial solid waste, non-hazardous sludge, conditionally
exempt small quantity generator waste and industrial solid
waste.
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Table 2. EPA Regulatory Activities Affecting Mercury Releases to the Environment.
Program Office/Region
Office of Air and Radiation
Regulatory Determination for
Electric Utilities
Regulatory Activities
Promulgate Rule on Mercury
Controls for Utilities
Attain Full Compliance by Utilities Industry
Fiscal Year
Target Date
2005
2008
Maximum Achievable Control
Technology Standards
1. Chlor-Alkali Facilities
2. Landfills
Promulgate MACT Proposals for Chlorine
Production, and Municipal Landfills
2001
Attain Full Compliance with MACT Proposals for
Chlorine Production and Municipal Landfills
2004
Integrated Urban Air Toxics Strategy
Develop Initial Urban Area Source Standards
2002
Complete Urban Area Source Standards
2004
Office of Water
Revisions to Mercury Water
Quality Criteria
Attain Full Compliance with Urban Area
Source Standards
Revise Human Health Water Quality
Criterion for Mercury (TMDLs)
2009
2001
Office of Solid Waste and
Emergency Response
Land Disposal Restrictions on Mercury
MACT Standards
Propose Land Disposal Restriction for
Mercury-bearing Hazardous Wastes
Propose Phase 2 MACT Rule for
Hazardous Waste Combustion
Propose MACT Standards for Boilers and
Industrial Furnaces Burning
Hazardous Wastes
2001
2001
2001
Urban Area Source Standards: The Integrated Urban Air
Toxics Strategy (Federal Register, 1999) is an important part
of EPA's national air toxics program. Under the national air
toxics program, EPA has and will continue to develop a
number of national standards for stationary and mobile
sources to improve air quality in urban and rural areas. The
Urban Air Toxics Strategy complements the existing
national efforts by focusing on further reductions in air
toxics emissions in urban areas. Emissions standards are
currently under development or have already been issued
for sixteen categories (Federal Register, 1992). The other
thirteen area source categories are new to the EPA's Source
Category list. EPA anticipates promulgating emissions
standards for these additional categories in FY 2004. Full
attainment will be in FY 2009.
Human Health Water Quality Criterion for Mercury and
Total Maximum Daily Loads (TMDLs): The Office of
Water (OW) is developing a revised human health water-
quality criterion for mercury. This revised human health
criterion is scheduled for release in FY 2001. In the longer
term, there is a programmatic need for a wildlife criterion
which would protect birds and terrestrial animals from the
effects of mercury. OW is conducting two pilot projects for
water bodies impaired by airborne deposition of mercury. If
the methodology is successfully demonstrated, TMDLs1
will be developed, mostly by the states, for all such water
bodies.
Land Disposal Restrictions for Mercury-bearing Hazard-
ous Wastes: The Office of Solid Waste and Emergency
Response (OSWER) is re-evaluating land disposal restric-
tions on mercury to consider alternatives to mercury
recovery and incineration. EPA is considering publication
of a proposed rule to revise the 40 CFR Part 268 Land
Disposal Restrictions treatment standards applicable to
12
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mercury containing wastes. The revisions under consider-
ation by the Agency will involve a comprehensive re-
evaluation of waste treatment standards. A proposed rule
is scheduled for FY 2001.
Phase 2 MACTRule for Hazardous Waste Combustion:
OSWER is planning to issue a proposal establishing
MACT standards for emissions of HAPs, including
mercury, from boilers and industrial furnaces which burn
hazardous waste. This rule follows on the Phase 1
hazardous waste combustion MACT rule which set
standards for incinerators, cement kilns, and lightweight
aggregate kilns which burn hazardous waste. A schedule
for the proposed rule has not been established but could
occur in FY 2001.
MACT Standards for Boilers and Industrial Furnaces
Burning Hazardous Wastes: EPA regulates air emissions
from hazardous waste combustors and boilers and indus-
trial furnaces (BIFs) under RCRA. The Office of Solid
Waste (OSW) is currently developing MACT standards for
hazardous-waste-fired industrial, commercial, and institu-
tional boilers and two more types of industrial furnaces -
halogen acid and sulfuric acid recovery for FY 2001.
3.2.2 Special Initiatives
Special Agency initiatives and activities that support the
development of the Mercury Research Strategy are
described below.
Persistent, Bioaccumulative Toxics Initiative: EPA is
committing, through the Persistent, Bioaccumulative,
Toxics (PBT) Initiative to create an enduring cross-office
program addressing the multimedia issues associated with
priority PBT pollutants. Mercury was identified as a
priority PBT, and the Agency convened the Mercury Task
Force (MTF) to develop a Mercury Action Plan. The cross-
agency work group that developed this action plan is
continuing to look for opportunities to address mercury
through a more integrated, multimedia approach.
The Great Lakes Binational Toxics Strategy: The Great
Lakes National Program Office (GLNPO) is undertaking
voluntary efforts to remove mercury from wastes, products,
and processes, with a goal of a 50 percent reduction by the
mid-2000s (EPA, 1997c). This is a joint undertaking
between the United States and Canada and addresses not
only mercury, but eleven other PBTs.
Hazardous Waste Reduction Voluntary Program: The
Office of Solid Waste and Emergency Response (OSWER)
is undertaking a voluntary effort to reduce the volume and
content of PBTs (including mercury) in hazardous wastes
by 50 percent before the end of FY 2005.
In all cases, these important Agency priorities benefit from
ORD research, both in terms of the assessment of mercury
risks to humans and wildlife and the characterization and
management of risks from mercury sources.
3.2.3 International Activities
A number of bilateral and multilateral programs offer the
United States an opportunity to promote and engage in
cooperative mercury efforts. These international activities
allow all nations to better understand and ultimately reduce
the risks of mercury and methylmercury exposures (Table
3). While some opportunities are voluntary and others
entail legally binding commitments, EPA's involvement in
international efforts is conducted within the context of its
existing statutory authority, especially with respect to the
Clean Air Act, as amended. Rather than being driven by, or
reacting to, international initiatives on mercury, the Agency
is trying to influence them proactively.
The United Nations Economic Commission for Europe
(UNECE), Convention on Long-Range Trans-boundary Air
Pollution (LRTAP) for Heavy Metals (UNECE, 1998): In
February 1998, the LRTAP Parties (47 member countries,
including the U.S., all in the Northern hemisphere) con-
cluded negotiations on a legally binding protocol on
mercury and other heavy metals. The protocol includes
obligations to control mercury emissions from stationary
sources and to establish, update, and report mercury
emission inventories. It also contains obligatory and
voluntary provisions regarding the use of mercury in
products.
The U.S. and 35 other LRTAP Parties signed the Heavy
Metals protocol in June 1998, agreeing in principle to
comply with the protocol even before it formally entered
into force. As of July 2000 six countries had ratified the
protocol; ten more ratifications are required for the protocol
to enter into force. The U.S. is in the process of completing
the steps required for ratification. Best Available Technol-
ogy (BAT) standards for new and existing stationary
sources must be applied two and eight years, respectively,
after the protocol is in force. In addition, EPA will submit
reports on its domestic inventory updates and other
matters by late 2000 and annually thereafter.
The Arctic Environmental Protection Strategy (AEPS)
(Arctic Council, 2000): The AEPS, ratified in 1991 by the
eight Arctic nations, is implemented through five working
groups, two of which are most pertinent to mercury: the
Arctic Monitoring and Assessment Program (AMAP) and
the Protection of the Arctic Marine Environment (FAME).
AMAP is responsible for monitoring the levels and
assessing the effects of selected anthropogenic pollutants
in all compartments of the Arctic. AMAP teams are
collecting data on sources transport, transformation, and
effects of persistent organic pollutants and heavy metals.
Mercury was designated by the international heavy metals
team to be the priority metal for AMAP Phase II: Trends
and Effects 1998-2002.
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Table 3. International Mercury Activities that Support the Development of the Mercury Research Strategy.
Program Office/Region
Office of Air and Radiation
UNECE LRTAP Convention,
Heavy Metals Protocol
Office of Air and Radiation &
Office of Research and
Development
UNECE LRTAP Convention,
Heavy Metals Protocol
Office of International Activities,
Office of Research and
Development, & Region 10
Arctic Council - Arctic Monitoring
and Assessment Program
Office of Prevention, Pesticides,
and Toxic Substances
CEC North American Regional
Action Plan on Mercury
Reg/on 5; GLNPO; OPPTS;
all EPA Offices
The Great Lakes Binational
Toxics Strategy
Region I; all EPA Offices
The North East Governors-Eastern
Canadian Premiers Mercury Action
Plan (June 1998)
Apply BAT to New Stationary Sources by 2
Years after Entry into Force of Protocol
Apply BAT to Existing Stationary Sources by i
Years after Entry into Force of Protocol
Upon Promulgation of
MACT standard
Upon Promulgation of
MACT standard
Submit Domestic Emissions Inventory Updates
and Research Results to Support Annual
Assessment of Protocol Compliance Results
2000 and
annually thereafter
Progress Report on 2nd Phase of Heavy
Metals Assessment
Arctic Council Ministerial Report on 2nd Phase
Assessment Results
Final Arctic Council Ministerial Report on 2nd
Phase Assessment Results
2000
2002
2006
Coordinate Implementation of the Mercury
NARAP Phase II over the Next Several Years.
2000 - 2005
Seek 50 percent Reduction Nationally in Deliberate
Use of Mercury, and 50 percent Reduction in
Releases of Mercury from Sources (air and water)
Caused by Human Activity.
Virtual Elimination of Mercury
2006
Beyond 2006
Virtual Elimination of Anthropogenic
Discharge of Mercury
2003
A progress report on heavy metals was presented to the
Arctic Council Ministers in Barrow, Alaska in October 2000.
It includes preliminary results of the first verification of the
Arctic Sunrise phenomenon at Barrow where elemental
mercury in the atmosphere suddenly depletes. Over the
next year, these and other data will be combined, inter-
preted, and incorporated into the Heavy Metals Phase II
final report due in September 2002. An Arctic Council
Action Plan (ACAP) is being developed. This action plan
will identify opportunities for international cooperation to
eliminate pollution in the Arctic, targeting mercury and
persistent organic pollutants. In addition, the PAME
working group is drafting a regional action plan to reduce
pollution emissions from land-based sources. The action
plan includes voluntary commitments by Arctic Council
members to reduce emissions of persistent organic
pollutants and heavy metals.
The North American Regional Action Plan on Mercury
(CEC, 2000): The North American Regional Action Plan
(NARAP) for mercury is one of a number of regional
undertakings that have stemmed from the North American
14
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Agreement on Environmental Cooperation (NAAEC)
between the governments of Canada, Mexico, and the
United States. The NAAEC established the Commission
for Environmental Cooperation (CEC) to facilitate activities
among the three countries. Under CEC Resolution #95-05,
the Sound Management of Chemicals (SMOC) Working
Group was established. This working group has been
involved in developing four NARAPs on PBTs of national
and regional concern, one being mercury.
The Mercury NARAP was developed in two phases.
Phase I was approved by the CEC Council in October 1997.
It set out the strategic framework and approach to be used
by the three countries as well as the ultimate goal. The
goal is to reduce mercury releases from human activities to
levels comparable to naturally occurring levels and fluxes.
Phase II, approved June 2000, fully endorses the over-
arching objectives and goal of Phase I. It identifies specific
mercury use and release reduction actions that the three
countries will undertake individually within their countries,
and together through a coordinated tri-national effort. An
implementation plan will be developed by mid-2001.
The Great Lakes Binational Toxics Strategy (EPA, 1997c):
On April 7,1997, the United States and Canada signed the
Great Lakes Binational Toxics Strategy. The strategy
establishes a collaborative process to virtually eliminate
persistent bioaccumulative, toxic substances resulting from
human activity in the Great Lakes basin. For mercury, the
strategy sets a U.S. challenge of reducing the use and
release of mercury 50 percent nationwide by 2006. The
Canadian challenge is to reduce the release of mercury 90
percent in the Great Lakes basin by 2000. The baseline for
the U.S. challenges is the most recent year for which there
was an inventory available at the time the strategy was
signed. For the release challenge, the baseline year is 1990;
for the use challenge, the baseline is the U. S. Geological
Survey's 1995 mercury consumption estimate.
The Northeastern States and Eastern Canadian Provinces
Mercury (NESCAUM, 1998): On June 8,1998, the New
England Governors/Eastern Canadian Premiers (NEG/ECP)
signed a resolution concerning mercury and its impacts on
the environment and adopted the Mercury Action Plan,
which has as its regional goal "the virtual elimination of the
discharge of anthropogenic mercury into the environment."
The NEG/ECP has established a task force to coordinate
and implement the Mercury Action Plan. The plan identi-
fies 45 specific actions to reduce mercury emissions.
These actions include: emission reduction targets for
specific source categories (e.g., municipal waste combus-
tors, medical waste incinerators, sludge incinerators, utility
and non-utility boilers, industrial and area sources), source
reduction, and safe waste management of mercury.
ORD has made a concerted effort to engage the Office of
International Activities (OIA) and those Regions involved
in the above programs in the preparation and review of the
Mercury Research Strategy. Each will benefit from the
scientific information and technical data resulting from the
implementation of the strategy.
1. A TMDL is developed for a water body if water quality
standards within the body are not being met using technology-
based or other effluent controls. It establishes the maximum
allowable pollutant loading for a water body (including
allocations for point and non-point source loads and a margin
of safety) that will result in compliance with established water
quality standards (EPA, 1999c).
15
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4.0 RESEARCH AND DATA GATHERING BY OTHERS
4.1 MERCURYASACROSS-MEDIA,
MULT1DISCIPLINARYPROBLEM
The current interest in mercury and its impacts on human
health began with the methylmercury poisonings in
MinamataBay, Japan, in the 1950s (EPA, 1997a). Since
then, a wide range of scientific and technical investigations
have advanced the worldwide understanding of the human
health impacts from acute and chronic exposures to
methylmercury. This understanding has been extended
over the years to fundamental insights on sources, routes,
wildlife effects, and to a lesser degree, risk management of
mercury and methylmercury. A thorough treatment of
EPA's knowledge on the subject of mercury is presented in
the Mercury Study Report to Congress, but there are still
key scientific questions that need to be addressed. A
recent example of addressing this need is the National
Academy of Sciences (NAS) report, ToxicologicalEffects
oj"Methylmercury-(NRC, 2000). The NAS report analyzes
the methylmercury reference dose and recommends a
number of research activities on human health effects.
By its very design and focus on the risk management
paradigm, ORD is uniquely positioned to lead an integrated
research program on assessing and managing risks from
mercury and methylmercury. The research proposed in this
strategy, however, cannot be accomplished by ORD alone.
Other public and private organizations (e.g., federal, state,
and local governments, academic institutions, industrial
associations) must be involved in addressing the key
scientific questions presented in Chapter 5.0. Research on
mercury can be most efficient and effective when under-
taken in collaboration with other organizations conducting
research in areas of common interest and need.
This chapter of the MJ?S" identifies organizations involved
in scientific and technical investigations, and data and
information gathering related to mercury and methylmer-
cury. This is not an exhaustive discussion, but is intended
to be indicative of the organizations conducting research
and collecting data pertinent to the six key scientific
questions and associated research areas presented in the
MRS. ORD intends to engage many of these organizations
(in some cases, collaborations are already underway) and
seek their assistance in achieving the goal of the MRS. A
brief summary of the organizations and their contributions
follows.
4.2 FEDERAL ACTIVITIES
Based on the input received from the various members of
the research strategy writing team, direct contacts with
other organizations, and a review of the literature (both
hard copy and on-line), a number of federal organizations
can make contributions to the Mercury Research Strategy.
These organizations and the work they perform are briefly
described below.
4.2.1 National Institutes of Health and the
National Institute for Environmental
Health Sciences
The National Institutes of Health (NIH) and the National
Institute for Environmental Health Sciences (NIEHS) have
been investigating the adverse human health effects of
methylmercury for a number of years. Investigations
address the mechanisms of action of methylmercury on the
nervous system and evaluate its effects on other systems
(e.g., endocrine, immune).
4.2.2 National Center for Health
Statistics and the Food and Drug
Administration
The National Center for Health Statistics (NCHS) collects
biomonitoring data on mercury concentrations in hair and
blood of examinees for the National Health and Nutrition
Examination Survey (NHANES) IV. This survey provides
information on the distribution of mercury exposures in the
general United States population, but does not provide
information on specific populations that may have higher
than typical exposures. The Food and Drug Administra-
tion (FDA) monitors mercury levels in fish sold in interstate
commerce.
4.2.3 U.S. Geological Survey
The U. S. Geological Survey (USGS) evaluates the mecha-
nisms of methylmercury bioaccumulation in fish and
wildlife species. One research program has correlated
mercury concentrations in sediment, water, and fish with
water and sediment parameters (Krabbenhoft, et al., 1999).
Determining the role of sediment microbial communities in
the methylation of mercury is another important USGS
program. Much of the research is associated with regional
assessments, such as those in the Great Lakes or the
Florida Everglades. The USGS continues to collect data on
mercury in commerce and has been conducting a program
to address mercury releases from mining operations in the
Western United States. It conducts research in the aquatic
and terrestrial transport, transformation, and fate of
mercury. ORD has worked closely with the USGS to
establish a coordinated research program for the investiga-
tion of ecological processes in the field and the collection
16
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of environmental data for model development and valida-
tion, particularly in studies related to the restoration of the
South Florida Ecosystem.
4.2.4 Department of Defense
In the context of the mercury life cycle, ORD is interested in
one of the most challenging issues facing the United States
over the long term, elemental mercury retirement. Mercury
retirement is currently being considered by the Department
of Defense (DOD) for its strategic stockpile of elemental
mercury. At a workshop in Baltimore in the Spring of 2000,
DOD personnel presented their efforts in addressing the
strategic stockpile and invited workshop participants to
join them in addressing this issue. They stressed that
DOD was not proposing to conduct research on retirement
alternatives, but was relying on a call for retirement
technologies to be considered as part of an Environmental
Impact Assessment that would be prepared.
4.2.5 National Oceanic and Atmospheric
Administration
The National Oceanic and Atmospheric Administration's
(NOAA) Atmospheric Research Laboratory (ARL), in
coordination with EPA and the Department of Energy
(DOE), develops numerical simulation models for atmo-
spheric mercury and other air toxics. Thus far, ARL has
focused on Lagrangian-type numerical frameworks (i.e.,
H YSPLIT), rather than three-dimensional fixed grids with
high-resolution nesting and complex chemistry like EPA's
Models-3/CMAQ. The National Exposure Research
Laboratory's (NERL's) Atmospheric Modeling Division is a
part of NOAA's ARL that has been assigned to work for
ORD. The division reports to the Director of ARL, so there
is close coordination between EPA and NOAA's research
activities.
4.2.6 Department of Energy
DOE has undertaken an extensive program in pilot and field
evaluations of control technologies for mercury emissions
from coal-fired utilities. EPA's National Risk Management
Research Laboratory (NRMRL) will participate in these
evaluations with DOE and the Electric Power Research
Institute (EPRI). The emphasis will be on technology
performance and cost effectiveness. DOE, in coordination
with ORD, is also studying non-thermal disposal alterna-
tives to mercury-bearing mixed wastes (including soils),
and alternatives to mercury use in fluorescent light bulbs.
DOE's Oak Ridge National Laboratory (ORNL) is conduct-
ing studies on the Arctic Sunrise phenomenon and
collecting data on landfill emissions and emission measure-
ment techniques.
4.3 STATE AND REGIONAL
ACTIVITIES
Many states conduct regular monitoring of mercury levels
in game fish that are used in setting fish consumption
advisories. In addition, many states conduct fish surveys
to assess methylmercury fish tissue concentrations.
Examples of state-specific and regional mercury research
activities are presented below. Engagement with these
regions and states provides a geographic component that
informs the MRSwA allows for the leveraging of informa-
tion and data that have been collected over the years.
4.3.1 EPA's Region IV and the State of Florida
The State of Florida's South Florida Mercury Science
Program is a multidisciplinary team effort (state and federal
agencies, universities, industrial groups and associations)
to understand and address mercury bioaccumulation in
Florida. The major focus of the research is on the Florida
Everglades. Research topics include the following: risks to
humans and wildlife from mercury, methylmercury concen-
trations in the food chain, pathways for transformation of
mercury to methylmercury, source identification and
transport of mercury species in air and water, and actions
to reduce mercury levels in fish and wildlife. ORD already
has an excellent working relationship with the state officials
leading this effort and has been involved in the research
aspects of the program for a number of years.
Region IV has teamed with ORD and Florida's Department
of Environmental Protection on the Everglades since 1992.
The Region manages a team of researchers who provide
quantitative, large-scale spatial and temporal biological,
water, and soil data on mercury and methylmercury in
South Florida. This data provides more multimedia
information on mercury and methylmercury than any other
geographic location in the United States. Results from this
effort are being developed into an empirical model that
addresses the interactions of numerous variables affecting
mercury bioaccumulation in the Everglades. It will provide
the basis for an ecological risk assessment, leading to
management recommendations affecting the restoration of
the Everglades ecosystem. Numerous new methods have
been developed for sampling, analysis, and interpretation
as part of this undertaking (Stober, 2000).
4.3.2 The New England States
The New England governors, in concert with the Eastern
Canadian premiers, have developed a Mercury Action Plan
to support research and analysis that improves regional
understanding of mercury sources, impacts, and cycling in
the environment (NEG/ECP, 1998). In this plan, two
objectives were identified relating to research, analysis,
17
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and strategic monitoring. These objectives are: (1)
research and analysis to improve understanding of mercury
sources, impacts, and cycling in the environment, and (2)
strategic monitoring of mercury emissions, deposition, and
fish tissue levels and environmental indicators to measure
and track progress.
4.3.3 Other Regional Contributors
Other EPA Regions are developing data and providing
information that contribute to the Mercury Research
Strategy. Region I has encouraged mercury return
programs where mercury-containing devices are turned in
by citizens and the mercury is recycled. The Region, along
with the Northeast States for Coordinated Air Use Man-
agement (NESCAUM), is also interested in mercury
retirement as mercury supplies exceed demand. The
Region co-hosted a workshop on mercury in products,
processes, and wastes with ORD during March 1999 in
Baltimore, MD. Region V has been a national leader in
addressing PBTs, including mercury. The Region has long
been a champion of mercury take-back programs and is
active in fostering collaborations with the private sector to
address mercury removal from products and processes.
The Great Lakes National Program Office (GLNPO), under
the auspices of the Binational Toxics Strategy, has been
working to virtually eliminate mercury in the Great Lakes.
GLNPO has also been collecting data in cooperation with
Canada on mercury deposition in the Great Lakes area
through the Mercury Deposition Network.
Regions VIII and IX are working with ORD and others to
address mercury mining issues. They hosted a workshop
on assessing and managing mercury from historic and
current mining activities, in November 1999 in San Fran-
cisco, CA. Region X has been involved in addressing
issues related to transboundary transport of persistent,
bioaccumulative toxics, including mercury. The Region co-
hosted a workshop with the Office of International
Activities and others on the subject during August 1999 in
Seattle, WA. The Region has expressed an increasing
interest in issues related to the "Mercury Sunrise" phe-
nomenon and Alaskan Native and Native American
mercury exposures. The Region also co-hosted a workshop
with ORD on aquatic and terrestrial transport, transforma-
tion, and fate of mercury in May 2000 in Southern Florida.
4.4 PRIVATE SECTORAC11V1TIES
Scientific activities are under way in some industrial
sectors to assess mercury use and releases. ORD is
already working with various industries and industrial
research and trade organizations to address research and
technical issues related to mercury management options.
These efforts will inform both industry and the Agency on
mercury and methylmercury risk assessment and risk
management for the industrial sector.
4.4.1 The Electric Power Research Institute
The Electric Power Research Institute (EPRI) has supported
a comprehensive research program on mercury for many
years. EPRI works with the electric utility industry to:
collect data on fuels (e.g., coal, oil), measure mercury
emissions and deposition of those emissions, develop and
test models on mercury fate and transport, conduct
integrated assessments of exposure and risk, and evaluate
control measures to reduce mercury emissions. EPRI has
sponsored research covering a broad spectrum of mercury
issues related to coal combustion, including the use and
effectiveness of mercury sorbents and coal cleaning. It has
been supporting the utility industry's data collection effort
in response to EPA's Information Collection Request (ICR)
on the mercury content of coal and mercury emissions from
coal-fired utilities. Since the 1980s, EPRI has sponsored a
series of international conferences on mercury as a global
pollutant. The last conference was held in Rio de Janeiro,
Brazil, in 1999 and the next one will be held in Minamata,
Japan, in 2001. Additional information on EPRI's mercury
research program can be found at its web site (http://
www.epri.com).
4.4.2 The Chlorine Institute
The Chlorine Institute is working with its members in the
chlor-alkali industry to reduce mercury use by 50 percent
as part of the Binational Toxics Strategy (EPA, 1997 c). In
the spring of 2000, ORD in cooperation with The Chlorine
Institute, EPA Regions IV and V, and OAR conducted a
mercury emissions sampling program at a chlor-alkali plant
in the Southeastern United States. ORD plans to continue
this cooperative relationship to gain an improved under-
standing of mercury emissions from chlor-alkali plants and
to resolve mercury mass balance issues associated with
plant operations.
4.5 OTHERDOMESTICACTrvniES
4.5.1 Non-Governmental Organizations
Over the years, non-governmental organizations and
citizens groups have played a critical role in addressing
mercury and methylmercury issues and focusing the
government's attention on the implications of mercury
pollution. The regulatory determination on controlling
mercury emissions from coal-fired utilities resulted from a
Consent Decree issued as part of a settlement agreement
between EPA and the National Resources Defense Council
(NRDC). Both NRDC, as part of the Environmental
Working Group (EWG), and the National Wildlife Federa-
tion (NWF) have issued reports on mercury in the environ-
ment within the past year (EWG, 1999;NWF, 1999). The
Mercury Policy Project is another non-governmental
organization involved in advancing both policy and
research issues related to mercury. ORD will engage these
18
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and other non-governmental organizations, as it moves to
implementation of the Mercury Research Strategy in the
coming year.
4.5.2 Academic Institutions
Academic research plays a critical role in advancing the
fundamental understanding of mercury and methylmercury
risk assessment and risk management. ORD recognizes
that many of the research needs associated with atmo-
spheric, aquatic, and terrestrial mercury transport, transfor-
mation, and fate can best be addressed by researchers in
the academic community. To this end, a Request for
Applications (RFA) was issued in FY1999 as part of ORD's
Science to Achieve Results (STAR) Grants Program on
aquatic and terrestrial transport, transformation, and fate of
mercury (EPA, 1998e). Nine grants were awarded at the end
of FY 1999 and are summarized in Appendix A. NCER is
now considering a second RFA on atmospheric transport,
transformation, and fate of mercury to be issued in F Y 2001.
This RFA will solicit research on many of the issues relate
to the chemistry, thermodynamics, and kinetics of atmo-
spheric mercury. Other academic research will also be
consulted for its relevance to the Mercury Research
Strategy. For example, EPAis working with the Energy &
Environmental Research Center at the University of North
Dakota to address fundamental issues associated with
mercury in combustion systems.
4.6 INTERNAnONALACUVniES
In the international arena, mercury has been a subject of
research for many years. There is ample evidence of the
breadth and depth of this international-scale commitment
to mercury research based on the Fifth International
Conference on Mercury as a Global Pollutant held in Rio
De Janeiro, Brazil, in 1999 (CETEM, 1999) Technical papers
on mercury and methylmercury research were presented by
researchers from Brazil, Canada, Finland, India, Japan,
Poland, Russia, Slovenia, and the United States, to name
just a few of the countries that were represented. These
technical papers described a broad spectrum of research
related to mercury risk assessment and risk management
research (e.g., human and ecological effects and exposure;
transport, transformation, and fate; risk management).
Government agencies in other countries (e.g., Denmark,
Germany, France) are also identifying adverse human
health effects of methylmercury and investigating mecha-
nisms of action on the nervous system. Assessments are
also being conducted in other countries to describe the
dose-response and set the No Observed Adverse Effects
Levels (NOAELs) and the Lowest Observed Adverse
Effect Levels (LOAELs) for methylmercury.
ORD will work with EPA's Office of International Activities
(OIA) and other Program Offices to advance mercury
research in the international arena. Cooperative interna-
tional undertakings are essential in addressing mercury and
its impact on the environment. The recent findings of the
National Academy of Sciences regarding the EPA's RfD for
methylmercury would not have been possible without the
many international research projects addressing the human
health impacts of methylmercury. Add the United States
involvement in a number of international agreements on
mercury (e.g., Great Lakes Binational Toxics Strategy, North
American Regional Action Plan, Arctic Monitoring and
Assessment Program, Convention on Long-Range
Transboundary Air Pollution) and it is clear that interna-
tional mercury research will contribute in many ways to
answering mercury risk assessment and risk management
questions. Where they have not yet been developed,
international strategies will be needed that include appro-
priate components addressing the research areas presented
in the Mercury Research Strategy.
4.7 CROSS-ORGANIZATIONAL
ENGAGEMENT
ORD is currently collaborating with a number of organiza-
tions on mercury research. The most effective vehicle for
engaging federal organizations is through the Committee
on the Environment and Natural Resources (CENR) under
the White House Office of Science and Technology Policy
(OSTP). Collaborations with DOE and the USGS are
already underway. ORD has engaged USGS on mercury
science and research through the USGS/EPA Mercury
Roundtable. This engagement is a direct result of com-
ments made by USGS on the draft of the J^ythrough
CENR and the realization that a collaboration on mercury
research presented a powerful opportunity for both
organizations. The first meeting of the Roundtable was
held in late-June 2000. USGS has already expanded its
representation to other organizations within the Depart-
ment of the Interior (e.g., National Park Service, Bureau of
Land Management, Fish and Wildlife Service).
EPAis working cooperatively with DOE's National Energy
Technology Laboratory (NETL), USGS, and the Electric
Power Research Institute (EPRI) to develop and evaluate
improved mercury measurement methods and more cost-
effective mercury emission reduction technologies. A team
of individuals from each organization is working together
to define and refine roles and responsibilities, identify
areas for collaboration, and coordinate the transfer of new
information obtained through the research conducted.
Understanding the characteristics of different coals and the
possibility of cleaning coal before it is burned are important
areas in which EPA is relying on other agencies and the
private sector. All of these organizations are working with
EPA's Office of Air Quality Planning and Standards
(OAQPS) and coal-fired utilities to enhance knowledge
about the mercury content of various coals. EPRI is
conducting studies on coal cleaning as an approach for
reducing mercury emissions from coal-fired boilers. DOE
19
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and EPRI will also play a lead role in testing innovative
emission control technologies, including multi-pollutant
controls, in pilot- and full-scale utility boilers.
ORD plans to engage a number of organizations on risk
communication research for mercury, especially targeted at
susceptible populations. Risk communication on mercury
has been almost exclusively tied to messages about
methylmercury in fish. Communicating both the benefits of
consuming fish and the accompanying risk of ingesting the
contaminants often found in fish is a complex process. The
40 states that have fish advisory programs on mercury also
have risk communication programs that typically target
susceptible populations. The extent to which these
messages are tailored to ethnically-diverse populations
varies. Research on factors that complicate communication
(e.g., prior beliefs and attitudes, silent questions and
concerns) when addressing people of diverse ethnic
backgrounds is also a critical component of successfully
communicating risk. A great deal of work in this area is
either disease-specific (e.g., transmission of HIV), behav-
ior-specific (e.g., smoking cigarettes), or agent-specific
(e.g., risks of exposure to lead or radon). Some general
work on risk communication appears to have been spon-
sored by organizations such as the National Science
Foundation. State governments, private foundations, and
various health agencies (e.g., Centers for Disease Control)
conduct research on communicating the risk of various
diseases and injuries.
In addition to research targeted at specific aspects of the
mercury problem (e.g., human health, management of
combustion sources), federal organizations and others are
conducting applied research and collecting scientific data
and information that informs EPA's efforts on mercury.
These efforts are mainly focused on geographic regions or
locales where mercury has been identified as a problem.
Examples include: (1) the National Estuary Program,
administered by EPA's Office of Water - working to restore
and enhance 28 nationally significant estuaries; (2) EPA's
Great Waters Program - charged to research and resolve
environmental issues affecting the Great Waters of the
United States (e.g., Great Lakes, Chesapeake Bay); and (3)
the National Estuaries Research Reserves System (NERRS),
administered by the National Oceanic and Atmospheric
Administration (NOAA) - conducting long-term research,
education, and stewardship of 23 national estuarine
reserves. More thorough descriptions of these examples,
and many others are presented in the Deposition of Air
Pollutants to the Great Waters: Third Report to Congress
(EPA, 2000a). ORD will engage these organizations to
determine how their programs can make contributions to
the Agency's mercury research program.
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5.0 RESEARCH AREAS, KEY SCIENTIFIC QUESTIONS AND
RESEARCH NEEDS
Mercury Research Strategy Goal
To provide information and data that reduce
scientific uncertainties limiting the Agency's
ability to assess and manage mercury and
methylmercury risks.
The Mercury Research Strategy was designed to identify
areas where the Agency's knowledge and understanding
of mercury can be improved. In preparing the MRS, six key
scientific questions were identified that require ORD's
attention. The answers to these questions will provide
information and data to assist the Agency in assessing and
managing mercury and methylmercury risks. This chapter
describes the methodology used to identify the research
areas and key scientific questions, and to prioritize
research needs. It also includes a discussion of how the
Agency is implementing research on the needs that were
identified. Funding allocations are presented, as are the
emphases for the mercury research program over the next
five years. The chapter concludes with a detailed presenta-
tion of each of the six key scientific questions and associ-
ated research needs.
5.1 MERCURYRESEARCH
PRIORITIES
5.1.1 Identification of Research Areas
The six research areas described in this Mercury Research
Strategy were identified through an interactive process
between the (ORD) and EPA's Program Offices and
Regions. ORD consulted with its EPA customers and
asked them to identify those areas in which a lack of
scientific and technical knowledge and data related to
mercury inhibited their ability to fulfill their missions. Input
received from the Program Offices and Regions was
categorized into broad research areas organized around the
risk paradigm. The research areas identified were: Human
Health Effects and Exposure; Ecological Effects and
Exposure; Transport, Transformation, and Fate; Risk
Management for Combustion Sources; Risk Management
for Non-Combustion Sources; and Risk Communication.
Writing teams comprised of ORD personnel and represen-
tatives from Program Offices and Regions were created to
address each research area. The lead writers for each of
these writing teams formed the MRS'Writmg Team.
5.1.2 Development of Key Scientific
Questions
The key scientific questions identified for each research
area were developed by the various writing teams. The
questions were formulated, and re-formulated, as the
writing process progressed. It was the goal of each of the
writing teams to capture the key scientific questions (in
some cases the key scientific question includes a series of
inter-related sub-questions) in a way that allows for the
development of long-term goals as part of the multi-year
research implementation plan. These long-term goals are
then translated into Annual Performance Goals (APGs) and
Annual Performance Measures (APMs) in accord with the
Government Performance and Results Act.
5.1.3 Prioritization of Research Areas and
Key Scientific Questions
ORD, in consultation with its Program and Regional Office
counterparts, established the priorities for the mercury
research program. The prioritization process was influ-
enced by an understanding of the regulatory and voluntary
drivers facing the Agency (Chapter 3.0). International
issues were integrated within each appropriate research
area. In addition, the research areas were evaluated by the
writing teams to determine the level of funding needed,
while maintaining a viable portfolio of research across the
six key scientific questions. Priorities are subject to re-
evaluation and adjustment depending on a number of
factors (e.g., progress in answering the key scientific
questions, influential regulatory deadlines, research by
other organizations). These factors require that priorities
and trends in emphasis be revisited on a year-to-year basis
as part of ORD's annual planning process.
5.1.4 Identification of Research Needs
In identifying the research needs for the Mercury Research
Strategy, the most influential resource was the Mercury
Study Report to Congress because it contains an extensive
analysis of the state-of-the-science understanding of
mercury and methylmercury. Each writing team reviewed
the research needs described in the Report to Congress
across the risk paradigm (i.e., human and ecological health
effects; human and ecological exposures; transport,
transformation and fate; and risk management for combus-
tion and non-combustion sources). The writing teams then
matched up research needs with the key scientific ques-
tions. ORD and the Office of International Activities (OIA)
lead a cross-cutting team addressing international mercury
issues.
21
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5.1.5 Prioritization of Research Needs
The research needs under each research area were priori-
tized using the following criteria:
• Provide timely scientific information and data needed to
inform current and future Agency decisions on mercury.
• Fill data and information gaps on mercury not addressed
by other organizations.
• Support the goals and objectives of ORD's Strategic
Plan (EPA, 1996; EPA, 1997b) which stress research in
accord with the risk assessment/risk management
paradigm.
ORD's overall research program covers a variety of topics.
Some of the investigations underway as part of other
research strategies may well contribute to advancing the
mercury research program. A preliminary review of the
Ecological Research Strategy, the Pollution Prevention
Research Strategy, and the Waste Research Strategy'(EPA,
1998c;EPA, 1998d;EPA, 1999b) indicates this possibility.
Where pertinent scientific information and technical data
are being developed under these or other ORD research
strategies, resource leveraging will be explored and, when
appropriate, employed. Where scientific information and
technical data are being developed by other organizations
(e.g., USGS, DOE), ORD intends to work collaboratively
with these organizations to convey their information and
data to appropriate Agency decision-makers. The focus
will be on work that complements ORD's efforts and is
critical to fully addressing the six research areas.
5.1.6 Peer Panel Review of the Mercury
Research Strategy
The last step in the prioritization process followed an
external peer review of the draft MJfS"conducted on
December 9-11,1999 in Washington, DC. Ten experts from
outside EPA were assembled to review the draft MRSwA
offer their individual and collective opinions on the
document. Because the Mercury Research Strategy
extends across the risk management paradigm, the peer
reviewers were selected based on their broad experience,
expertise, and the various disciplines that they represented
(from risk assessment through risk management). The MRS
Writing Team was particularly interested in the opinions of
the peer reviewers from an interdisciplinary perspective.
The writing team wanted to be sure that the scientific
issues around mercury and methylmercury were adequately
addressed across all research areas. By and large, the peer
panel found the priorities to be appropriate, but did
recommend an increased emphasis on atmospheric
transport, transformation, and fate of mercury. That
recommendation and a number of other suggestions were
incorporated into this final version of the MJ&.
5.2 TAKING ACTION ON IDENTIFIED
PRIORITIES
In order to achieve the MJfSgozl, ORD is undertaking and
sponsoring research that addresses both mercury and
methylmercury risk assessment and risk management
questions. This research is being conducted by scientists
and engineers in ORD laboratories and centers, at universi-
ties, by the private sector, and with other federal organiza-
tions. ORD plans to take the lead in integrating the results
from this research into information that can be used to
inform future decisions by the Agency's Program Offices
and Regions. Research priorities identified in the Mercury
Research Strategy will be used to guide decisions relating
to ORD funding of in-house research, sponsored research,
and collaborative mercury research efforts.
5.3 STRATEGIC DIRECTIONS
Mercury is a human and ecosystem risk and a high priority
both within and outside of the Agency. Consequently,
internal stakeholders (e.g., Program Offices, Regions) and
external stakeholders (e.g., regulated entities, environmen-
tal groups, community decision-makers at all levels, the
general public, international entities) have an interest in the
Mercury Research Strategy and its priorities. Stakeholders
are particularly interested in research program sequencing
and timing in order to determine whether it is consistent
with their needs, interests, and Agency target dates. The
AffiS'is designed to provide broad strategic directions for
ORD's mercury research program in the coming five years.
It is not intended to convey detailed information on
specific projects. Specifics will be presented in a subse-
quent ORD mercury research multi-year implementation
plan.
ORD's current emphases for the mercury research program
fromFY2001 through FY 2005 appear below. This projec-
tion was made with an assumed stable funding level of
$6.1M per year over that time period. This estimate
incorporates funding from ORD's National Center for
Environmental Research (NCER) that supports a research
program on aquatic and terrestrial transport, transforma-
tion, and fate (Appendix A). Of the $6.1M, approximately
$2.0M will be targeted toward the Science to Achieve
Results (STAR) Grants Program and the remainder will be
used to support in-house research activities. Funding
projections for the six key scientific questions are pre-
sented in Figure 3, but could well change over the course
of the coming years. The further into the future the
projections go (e.g., FY 2003 - 2005), the more uncertain
they become. For each of the research areas, the rationale
for the trends follow.
22
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Figure 3. Research Emphases for Mercury Research Strategy'Key Scientific Questions (FY 2001- FY 2005).
5.3.1 Transport, Transformation, and Fate
Research on mercury transport, transformation, and fate
will fluctuate somewhat, but remain relatively stable
through the FY 2001 -2005 period. Answers regarding this
research area will take some time to resolve because
transport, transformation, and fate of mercury is so complex
once it enters the environment. This research is consid-
ered a high priority and will allow an improved understand-
ing of mercury in the environment in terms of any future
regulatory efforts. Ultimately, such understanding will lead
to more cost-effective risk management approaches for
mercury and methylmercury. Expertise in ORD is available
in the National Exposure Research Laboratory (NERL), but
will be supplemented by a series of projects under the
STAR Grants Program. (Refer to Appendix A for additional
information.)
5.3.2 Risk Management for Combustion
Sources
Research to manage risks from combustion sources
addresses the highest near-term mercury priority and will
require a significant proportion of the J^^ybudget from FY
2001 through FY2003, with a gradual decrease thereafter.
Combustion risk management research is needed to
provide the Agency with the latest information on control
technology performance and cost. This will support the
development of an official regulatory proposal for coal-
fired utilities by FY 2004. EPA's National Risk Management
Research Laboratory (NRMRL) has the facilities and
expertise to conduct this research and is working with
other federal agencies, including DOE, USGS, and EPRI, to
demonstrate the most promising technologies for managing
mercury from combustion sources.
5.3.3 Risk Management for Non-Combustion
Sources
Research to manage risks from non-combustion sources
will be modest in F Y 2001 and F Y 2002, but then increase
over the FY 2003-2005 time frame as the need for risk
management research for coal-fired utilities decreases and
other mercury sources become more prominent. The
research will provide information to support future
assessments, rulemaking, and voluntary actions with an
23
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early emphasis on source characterization. Expertise in
source characterization and control technology for non-
utility sources of mercury and methylmercury is available in
NRMRL. Other federal agencies (e.g., USGS, DOE) and
private organizations (e.g., the Chlorine Institute) must also
be engaged.
5.3.4 Ecological Effects and Exposure
Research on the effects of methylmercury have been
demonstrated in ecological systems (EPA, 1997a), but there
is a need to learn more about its effects, particularly with
respect to fish-eating wildlife. Ecological research will
assist the Office of Water (OW) in the development of
aquatic and wildlife water quality criteria and will gradually
increase over the F Y 2001 -2005 period. This research will
be split evenly between effects and assessment activities.
Expertise is available within ORD for both types of research
(National Center for Environmental Assessment - [NCEA]
and National Health and Environmental Effects Research
Laboratory - [NHEERL]), but research being conducted by
other federal agencies such as the USGS and projects
under the STAR Grants Program also contribute to ORD's
efforts in this research area.
5.3.5 Human Health Effects and Exposure
The National Academy of Sciences (NAS) report on the
health effects of methylmercury supported EPA's reference
dose (RfD) of 0.1 micrograms per kilogram body weight per
day as a scientifically justified level to protect human
health. There are, however, several research areas identified
in the NAS study that need to be addressed. Also, there is
a continuing need for ORD to support OW in the develop-
ment of a revised human health water quality criterion for
mercury in F Y 2001, and to assist OAR in promulgating
regulations to control mercury from coal-fired utilities in F Y
2005. Level support in this research area is projected
through the F Y 2002 - F Y 2005 time frame. NCEA is capable
of providing technical support and conducting risk
assessments, and is leading this effort.
5.3.6 Risk Communication
Research to improve communication to populations at risk
of elevated exposures to methylmercury from fish will
fluctuate slightly over the FY 2001-2005 period. The
Agency needs to develop communication approaches to
address risks specific to those who consume large quanti-
ties offish (e.g., persons of Native American and Asian
ethnicity) and those who are at heightened risk because of
nervous system vulnerability (e.g., maternal-fetal pair,
nursing mother-infant pair, and young children). NCEA will
be responsible for this effort and will use both contracts
and cooperative agreements in its undertaking. NRMRL is
also available to provide research and support on technical
information transfer vehicles and venues as part of ORD's
efforts in stakeholder engagement.
5.3.7 Strategic Directions Summary
The six key scientific questions in the MRSvi'vA meet
domestic regulatory commitments and offer international
opportunities for addressing mercury. Pressing policy and
legislative issues drive ORD's human health and environ-
mental research priorities. While the Mercury Research
Strategy remains grounded in the risk management
paradigm, addressing Program Office and Regional
research needs over the next several years is central to its
success; ORD plans to focus on those research needs in
the near term by stressing the transport, transformation,
and fate and combustion risk management research areas.
In the longer term, research that advances the understand-
ing of human health effects and exposure, ecological
effects and exposure, and non-combustion risk manage-
ment will be emphasized. Research on communicating the
risks of methylmercury exposure to those individuals and
groups at greatest risk will be an ongoing effort.
5.4 DETAILED DISCUSSION OF
RESEARCH AREAS, KEY
SCIENTIFIC QUESTIONS, AND
RESEARCH NEEDS
This section of Chapter 5.0 provides a detailed description
of the research to be undertaken for each of the six key
scientific questions and associated research areas. Each
description includes a discussion on background, program
relevance, prioritized research needs, research results, and
measures of success. The description also contains a list
of preliminary performance goals that will be used in
mapping out the multi-year implementation plan for the
mercury research program. The research needs are
identified in order of their relative priority. Each is accom-
panied by a narrative, the intent of which is to describe the
type of work that would be required to address the need.
5.5 TRANSPORT, TRANSFORMATION
AND FATE
5.5.1 Key Scientific Question
How much methylmercury in fish consumed by the
U.S. population is contributed by U.S. emissions
relative to other sources of mercury (such as natural
sources, emissions from sources in other countries,
and re-emissions from the global pool); how much
and over what time period, will levels ofmethylmer-
cury in fish in the U.S. decrease due to reductions in
environmental releases from U.S. sources?
24
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5.5.1.1 Background
Mercury bioaccumulates most efficiently in the aquatic
food web. Fish-eating birds and mammals at the top of the
food web generally have higher methylmercury concentra-
tions. Nearly all of the mercury that accumulates in fish
tissue is methylmercury. Inorganic mercury, which is less
efficiently absorbed and more readily eliminated from the
body than methylmercury, does not tend to bioaccumulate.
The Mercury Study Report to Congress supports a
plausible link between releases of mercury from industrial
and combustion sources in the U.S. and methylmercury in
fish. However, fish methylmercury concentrations may
also result from existing background concentrations
(mercury from natural sources, as well as re-emitted
mercury deposited from previous human activity) and
deposition from the global reservoir (which includes
mercury emitted by other countries).
Given the current scientific understanding of the environ-
mental fate and transport of this element, it is not possible
to quantify how much, and over what time period, levels of
methylmercury in U.S. fish will be reduced by reductions in
environmental releases from United States sources. Also,
it is unclear how much of the methylmercury in fish
consumed by the U.S. population is contributed by
emissions from other United States sources (such as
natural sources and re-emissions from the global pool). As
a result, decision makers do not have quantitative informa-
tion to relate potential reductions in environmental releases
to reductions in exposure.
5.5.1.2 Program Relevance
As methylmercury is the primary route of exposure to both
humans and wildlife, it is critical to understand the relation-
ship among methylmercury in fish, levels of ambient
mercury in the environment, and emissions from all
sources. It is accepted that fish consumption dominates
the pathway for human and wildlife exposure to methylmer-
cury. Therefore, a better understanding of this pathway
and, to the extent possible, the quantitative relationships
among fish intake, methylmercury burdens, residuals in the
environment, deposition and emissions, will reduce
uncertainties in both risk assessment and risk management.
Information on this issue will assist the Agency in prioritiz-
ing the management of the diverse sources of mercury in
the environment including regulation of combustion
sources, pollution prevention activities, remediation of
residuals, and international activities. The research being
conducted under the Office of Research and
Development's (ORD) Science to Achieve Results Program
(STAR) will support the first and third prioritized research
needs described below.
5.5.1.3 Prioritized Research Needs
• Improved understanding of the transport, transforma-
tion, and fate of mercury in the atmosphere.
• Enhanced monitoring of atmospheric mercury deposi-
tion for model application.
• Improved understanding of the transport, transforma-
tion, and fate of mercury in the aquatic and terrestrial
media.
• Enhanced monitoring of mercury and methylmercury in
the aquatic and terrestrial media for improved risk
management.
Research and monitoring needs have been identified in
four categories that follow the predominant pathways of
exposure from emissions to fish uptake: atmospheric
transport, transformation, and fate processes; deposition
of mercury from the atmosphere to terrestrial and aquatic
environments; fate, transport, and transformation pro-
cesses in aquatic and terrestrial environments; and
monitoring of spatial and temporal patterns of mercury and
methylmercury in fish and sensitive environments. The
key scientific question encompasses a number of subsid-
iary questions, including: factors influencing global,
regional, and local mercury cycles; factors controlling local
deposition and methylation of mercury; and effective
monitoring programs.
Improved understanding of the transport, transformation,
and fate of mercury in the atmosphere. A need exists to
provide quantitative estimates of air concentrations and
deposition of elemental mercury, reactive gas-phase
mercury, and paniculate mercury in the U.S. to improve the
Agency's understanding of the fate, transport and
transformation of mercury. Improvements in atmospheric
models will be important in the next few years. Obtaining
information on the chemical species and physical form of
mercury in emissions, in the atmosphere, and in deposition
is vital to accurately modeling the transport and fate of
mercury. There is a clear need for atmospheric models
(range of 50 to 200 kilometers) to be used in the develop-
ment of emissions limits to protect water quality, human
health, and ecological health.
• Information from an atmospheric modeling framework.
This framework will be based on ORD's new multi-
pollutant air modeling system (Models-3), which is
being developed and tested for ozone and paniculate
matter by National Exposure Research Laboratory
(NERL) researchers. This new system will replace the
highly-parameterized modeling approaches for mercury
now in use. The largest process uncertainties are in-
cloud chemistry, in-air chemistry and dry deposition of
oxidized mercury gas, and these issues will be the focus
of a future STAR Request for Applications. As part of
this effort, available meteorological, land use, and
emissions data will be collected, formatted, and included
in the modeling framework. Model runs will be per-
25
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formed using seasonal aggregation approaches to
produce an annual mercury depiction that includes
source attribution, providing better estimates of the
distribution of atmospheric deposition.
• Field measurements of spedated elemental and
oxidized mercury concentrations in air throughout a
region at varying altitudes, to characterize gaseous
and aqueous processes. These data will be used to
validate models of atmospheric chemistry affecting
mercury deposition and will also facilitate process
understanding. NERL's researchers are currently
collecting information in South Florida as part of
existing interagency projects involving federal, state,
and local agencies. The study includes improved
inventories of emission sources in the South/Central
Florida region, characterization of the vertical atmo-
spheric profile in the region, including the identification
of trace elements and their relative concentrations, and
atmospheric modeling of the southern and central
Florida atmosphere. Results will be used to determine if
global, continental or natural forces govern mercury
deposition in the region. A protocol will be developed
suitable for other regions of the country. This type of
study has been identified as a critical need in address-
ing source attribution issues in South Florida, particu-
larly in distinguishing between local and global sources.
• Short-range atmospheric transport models (50 - 200
kilometers) to predict air concentrations and deposi-
tion. This modeling range is needed for many analyses,
such as Total Maximum Daily Load (TMDL) calculations
used to link specific sources on a local scale to deposi-
tion in specific watersheds and water bodies that may
be 10- to 100-200 km distant. There are no existing
models that are well adapted to this scale. Current
urban-scale models generally address only 50 km, which
is too small, while national/regional-scale models
(covering nearly half the U.S.) do not have sufficiently
fine resolution. NERL researchers will examine adding
this scale to its current models.
To provide quantitative estimates of air concentrations and
deposition of elemental mercury, reactive gas-phase
mercury, and particulate mercury in the U.S. that are
associated with sources outside the U.S., the following
scientific information is needed:
• Information on the atmospheric fate of mercury species
in various scenarios. Little is understood about the
atmospheric chemistry and fate of mercury in the Arctic,
and especially of a recently observed mercury depletion
event occurring during the Arctic Sunrise, when
photolytic reactions significantly affect the behavior of
atmospheric mercury and its deposition during the
Spring months. The Agency needs to understand the
mechanisms for atmospheric mercury depletion, whether
the mercury is becoming particle-bound and/or trans-
forming to reactive gaseous mercury which affects
deposition rates and subsequent bioaccumulation, and
whether similar processes occur for ozone depletion.
The answer to these questions are critical because
partitioning to particulate-and reactive gas-phase could
increase the possibility for bio-uptake through the food
chain once deposited. This event occurs just prior to
the time when Arctic ecosystems are most active.
Preliminary research on this topic is being conducted by
NERL researchers and researchers from other organiza-
tions (e.g., DOE) and is sponsored by OIA.
• Information on transport mechanisms affecting cross-
boundary pollution. Recent scientific evidence points
to a rapid (3-5 day) trans-Pacific transport mechanism
tied to meteorological conditions that could bring
persistent bioaccumulative toxics (PBT) contaminants,
including mercury, to the west coast of North America,
Alaska, and the Arctic. The data show higher levels
being transported in late Winter-Spring, concurrent with
the timing for Arctic Sunrise. The probabilistic nature of
the jet stream controlling trans-Pacific toxic compound
(mercury) transport needs to be understood if the Arctic
Spring event is to be fully appreciated. This is a topic
being pursued by OIA as part of an International
Mercury Strategy.
• Field-test results of a mercury measurement technology
that has been developed to determine both urban and
background concentrations of gas-phase elemental
mercury andparticulate mercury. These measure-
ments, coupled with trace element and back trajectory
analyses, permit the modeling of mercury transport to
the U.S. from sources abroad. Through international
cooperation, similar methods can be used abroad to
enhance the U.S. emissions mass-balance analysis.
These instruments would be used to evaluate the
effectiveness over time of the United States and
international mercury emission controls. Early interna-
tional harmonization of instrumentation and mercury
sampling protocols is also needed to compare data and
identify which data are most appropriate for use in
trends assessment and modeling. Again, this is a topic
being pursued by OIA as part of an International
Mercury Strategy.
EPA must also begin the development of a global scale
model for mercury transport, transformation, and fate,
including improved emission inventories. Risk manage-
ment actions to reduce global levels of background
mercury are dependent on an understanding of the
mechanisms driving mercury flux, which aids in the
identification of effective mediation. Without a better
understanding of mercury flux from existing mercury pools
in the oceans, wetlands, aquatic sediments, Arctic tundra
and ice sheets (and wherever else it is sequestered), the
context for estimating the current or near-term mercury
emissions from anthropogenic sources will be ill-defined.
There is a need to establish time lines for natural emission
processes.
26
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Research in the Arctic is very important because of unique,
natural meteorological conditions there which enhance
atmospheric transport of contaminants to the Arctic and
then trap them there due to cold conditions. Unique
atmospheric transformation processes for mercury are just
beginning to be investigated in the Arctic. Researchers are
learning that transformation from elemental to reactive
gaseous mercury (RGM) is enhanced with increased
deposition in Spring. Because mercury and other toxics are
trapped there, they tend to be highly bioconcentrated in
organisms which have short food chains to top predators,
including humans. The most vulnerable populations to
mercury exposure are those reliant on indigenous foods
tied to fish consumption, and Alaska has native tribes and
villages which depend heavily on subsistence foods,
including polar bear and marine mammals, and fish-eating
birds and their eggs. Research is needed in the Arctic, to
understand unique processes, and ecological and human
health linkages.
An additional concern is the effect of global warming in the
Arctic, and potentially enhanced release and methylation
rates for mercury over the next 20-100 years because of
warming trends. There is a need to understand the relative
importance of aquatic transport of mercury across interna-
tional boundaries. Tracers can be used to identify current
and historic mercury emitter source types. Significant
quantities of mercury may be transported in dissolved or
particulate form within aquatic systems to food chain
receptors, either from direct discharge, including erosion of
soils or sediments within a watershed, or through air
deposition to water bodies. Mercury may also cross
international boundaries via shared waters. Because the
Mercury Research Strategy is focused primarily on
resolving domestic issues related to mercury and methylm-
ercury risk assessment and risk management, these topics
must be addressed in the larger context of the international
implications of mercury.
Enhanced monitoring of atmospheric mercury deposition
for model application. There is a need to improve the
monitoring of atmospheric mercury deposition. NERL will
begin development of a coordinated mercury monitoring
program, in cooperation with the USGS and other federal
and state agencies, through installation of comprehensive
deposition monitoring stations in highly impacted, highly
sensitive geographic regions such as South Florida, the
Northeast, the upper Midwest, and the Arctic. Of particu-
lar importance is obtaining data on the spatial and temporal
distribution of mercury deposition to determine source-
receptor relationships and to measure patterns of long-
range deposition. The objective is to quantify the contri-
butions of mercury to terrestrial and aquatic systems from
local, regional, and global sources. To address this
question, ORD has proposed the development of special-
ized platforms for atmospheric mercury deposition monitor-
ing and source attribution. The platforms will be capable of
comprehensive, speciated measurements of mercury and
related species, and will provide deposition data to
compare with source-signature information. Platforms can
provide valuable information on mercury deposition
resulting from international sources, and will contribute to
agreements such as the United States-Canada Binational
Agreement and the North American Regional Action Plan
for Mercury developed by the North American Commission
on Environmental Cooperation. The platforms will have the
capability to report on hourly-to-daily, dry and wet
deposition of speciated mercury needed for transport and
fate models, source identification, controls planning and,
ultimately, direct measurement of mercury control benefits.
Improved understanding of the transport, transformation,
and fate of mercury in the aquatic and terrestrial media.
There is a need to develop a better understanding of the
processes (especially microbial and plant-mediated
processes) that mediate ecological exposures to methylmer-
cury. A key need is understanding the environmental
cycling of mercury, especially the characteristics that
induce methylation of mercury in ecosystems, and the
pathways of mercury and methylmercury exposures to fish
and marine mammals. In particular, the role of sulfur and
selenium in controlling the toxicity and/or bioavailability of
methylmercury is poorly understood. Terrestrial and
aquatic models incorporating current process understand-
ing at different scales will be developed and validated.
These models must be fully consistent and integrated with
the atmospheric models discussed above. Fundamental
research is being conducted as part of the NCER's STAR
Grants Program (Refer to Appendix A).
In cooperation with other federal, state, and local agencies
and industrial groups, ORD will also complete field and
model studies in South Florida, and then test and apply the
techniques developed to the Northeast and Midwest along
the Canadian border, to western mining issues, and to
coastal and high-elevation ecosystems. The long-term
goal is to develop a spatially structured model for describ-
ing and predicting the processes controlling mercury and
methylmercury exposures for fish and wildlife under current
and restoration conditions. The objective of the project is
the construction of biogeochemical and community
bioaccumulation models that interface with the hydrology
and water quality models that are the basis for evaluating
restoration goals. Such a linked, spatially distributed
model will be critical for assessing multiple interactive
stressors, for analyzing the spatial component of mercury
and methylmercury exposures (e.g., methylmercury
concentrations in local fish populations vs. nesting/
foraging areas for wading birds), and for evaluating the
effectiveness of criterion-based restoration goals. The
work in South Florida presents a unique opportunity to
leverage ongoing studies with other federal agencies (e.g.,
Fish and Wildlife Service, National Park Service, EPA
Region IV), the Florida Department of Environmental
Protection, the Florida Game and Fish Commission, the
South Florida Water Management District, and the Electric
27
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Power Research Institute. Lessons learned in this ongoing
project will be applied nationwide.
Critical questions for wildlife exposure and biological
transport to humans include: (1) to what extent does
transboundary transport of mercury occur via migratory
species when boundaries are shared between the U.S. and
other countries (including shared water bodies), (2) and
how significant is this fish and wildlife migration for
vulnerable U.S. wildlife and human populations due to
uptake through the food chain? EPA knows that older fish
of some species have elevated levels of mercury, and this is
also true of beluga whales and sea otters. Likewise, there
are concerns for mercury levels in birds such as eider (an
endangered species) and loons. Information about
migratory patterns and behavior of migratory fish, marine
mammals, migratory birds and other species of importance
in the food chain is needed and will be addressed as part of
the International Mercury Strategy.
EPA believes that this is an important research area, in that
more information is becoming available showing that
migratory species with body burdens of toxics (which
could be enhanced by their spending time in more highly
polluted areas in other countries, such as Russian waters,
or areas near industrial Asian sources) can release the
bioaccumulated contaminant to the environment to which
they migrate, and enhance bio-uptake there. It is known
that the large predatory fish, tuna, is one of the most wide-
ranging animals, can cross the Atlantic in fewer than 50
days, and lives to be 40 years old. Migratory salmon and
whales can spend time in Russian waters and then migrate
back to Alaska, and migratory birds do the same. These
are all eaten directly by indigenous peoples in Alaska, and
bird eggs are also consumed. They constitute a large part
of the indigenous diet. Recent studies of PCBs in bird
eggs in Alaska showed elevated levels. Fish in the Bering
Sea are a tremendous resource for consumers there and
also in the lower 48 States. It is important to know if Arctic
species are being more contaminated via direct migration to
areas where uptake can be enhanced, or indirectly through
food linkages to such more highly-exposed animals. It is
premature to say that transboundary linkages are insignifi-
cant from a food chain perspective.
Enhanced monitoring of mercury andmethylmercury in
the aquatic and terrestrial media for improved risk
management. The Clean Water Action Plan (EPA, 1998a)
calls for a survey of a wide range of pollutants in fish
tissue (including mercury). There are two basic goals: (1)
provide a statistically representative distribution of those
chemicals known to accumulate in fish flesh and (2)
determine whether there are other chemicals of concern.
Designed by ORD's Environmental Monitoring Assess-
ment Program (EMAP) Program and administered by OW,
this survey is statistically based so that it is repeatable and
able to detect trends in mercury and to measure progress
toward attaining Government Performance and Results Act
(GPRA) goals. This technique has proven effective in a
survey of northeastern lakes (Yeardley, et al., 1998). To
complement the national survey, there is a need to develop
a longer-term monitoring program which links existing and
planned deposition monitoring sites with sentinel environ-
ments where mercury methylation is most likely to occur
(e.g., wetlands).
5.5.1.4 Research Results
Results from this research will provide an improved
understanding of the fate and transport of mercury and
methylmercury in all environmental media and will allow the
Agency to identify those mechanisms that are most active
in mercury transformation processes. Linked to an
improved understanding of mercury releases from sources
and sinks, this research will also allow the Agency to better
estimate U.S. contributions to mercury in air and water, and
on land. Research on transport, transformation and fate
will also indicate how reductions in mercury through both
regulatory and voluntary actions result in concomitant
reductions in methylmercury in both humans and wildlife.
This work will be particularly useful for risk managers when
considering technological approaches to managing
methylmercury in aquatic and terrestrial settings.
5.5.1.5 Measures of Success
Researchers hope to advance the following:
• Measurable improvement in the scientific understanding
of the linkage among methylmercury in fish, ambient
mercury in the environment, and emissions.
• Identification and control of other pollutants that
exacerbate or minimize the mercury problem (e.g., acid,
sulfur, selenium, nutrients).
• Completion of a national sampling plan for methylmer-
cury and other persistent chemicals in fish tissue.
• Successful demonstration of a monitoring platform
capable of measuring the spatial and temporal distribu-
tion of mercury deposition to determine source-receptor
relationships, and to measure patterns of long-range
deposition.
• Completion of a multimedia integrated modeling system
capable of quantifying regional exposure to mercury; of
evaluating the relative importance of local, regional, and
global sources of mercury; and of determining the
importance of natural sources, re-emitted mercury
formerly deposited from anthropogenic and geological
sources, and new emissions.
5.5.1.6 Preliminary Performance Goals
• By 2003, develop a continuous ambient monitor capable
of distinguishing atmospheric mercury species.
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By 2006, provide an improved model for mercury in
terrestrial and aquatic systems capable of tracking the
fate of mercury from sources to concentrations in fish
tissue.
By 2008, produce an improved atmospheric fate and
transport model for mercury capable of distinguishing
among sources of mercury deposition; along with an
assessment of atmospheric mercury transport and fate,
including an enhanced scientific understanding of, and
then an improved inventory for, the chemical and
physical forms of mercury emissions.
5.6 RISKMANAGEMENTFOR
COMBUSTION SOURCES
5.6.1 Key Scientific Question
How much can mercury emissions from coal-fired
utility boilers and other combustion systems be
reduced with innovative mercury and multi-
pollutant control technologies; what is the
relative performance and cost of these new
approaches compared to currently available
technologies?
5.6.1.1 Background
Combustion systems that burn fossil fuels such as coal or
waste materials containing mercury are major sources of
mercury emissions to the air. Mercury emissions from
these anthropogenic sources eventually get deposited in
water bodies or on land. The amount of mercury deposited
in the United States that can be directly attributed to
domestic combustion sources remains uncertain. However,
a report released in 1998 by the Northeast States for
Coordinated Air Use Management (NESCAUM) contains
results from regional modeling studies supported by EPA
(Regional Lagrangian Model of Air Pollution [RELMAP])
that indicate 77 percent of mercury emissions (anthropo-
genic and natural) deposited in the Northeast are from
sources within the United States; and only 23 percent come
from the global pool (NESCAUM, 1998). In order to reduce
the risks of mercury over time, cost-effective strategies are
needed both domestically and internationally to minimize or
eliminate mercury emissions from combustion facilities and
other anthropogenic sources. While increased use of
natural gas for power generation and implementation of
recent Clean Air Act (CAA) regulations for several types
of waste combustion systems will result in some reductions
of combustion-generated mercury, combustion facilities
remain a significant source in the United States (account-
ing for 87 percent of the total point source emissions) with
coal-fired utility boilers being the largest single source type
(EPA,1997a).
5.6.1.2 Program Relevance
A substantial reduction of mercury emitted from waste
combustion systems is expected to occur over the next
several years as final emission standards promulgated by
the Office of Air and Radiation (OAR) for municipal waste
combustion systems (MWCs) and medical waste incinera-
tors (MWIs) are implemented, and standards proposed by
the Office of Solid Waste (OSW) for hazardous waste
incinerators (HWIs) are finalized. However, standards for
electric utilities and other commercial and industrial boilers
have not yet been proposed. Current concerns about the
lack of adequately demonstrated, cost-effective mercury
emission control technologies applicable to coal-fired
boilers and associated equipment pose constraints to
development of mercury emission reduction requirements
for these sources. As a result, OAR has identified
research needs on emission reduction options for utility
boilers as its highest mercury research priority. To address
OAR's needs, mercury combustion control research will
focus on determining the cost and effectiveness of viable
options to reduce mercury releases from coal-fired boilers.
While the emphasis will be on coal-fired boilers, fundamen-
tal research on mercury behavior in combustion systems
will be applicable to other boiler types, including those
waste-burning industrial boilers and furnaces that OSW
has identified as priorities for research. The research
results will also be useful to international organizations and
countries concerned with mercury emissions from combus-
tion sources. ORD will work with the Office of Interna-
tional Activities (OIA) to develop appropriate technology
transfer documents that summarize research findings and
to provide technical support for any international demon-
strations.
Reducing mercury emissions from combustion sources is
complex because there are a wide variety of fuels and waste
streams and many different types of combustion configura-
tions, flue gas cleaning methods, and operating modes.
Conventional options such as fuel switching, fuel pre-
treatment (i.e. coal cleaning), waste feed limitations and
activated carbon injection are available to reduce emis-
sions; however, there are many instances where these
approaches do not achieve adequate emission reductions,
are not practical, or have been inconsistent or ineffective in
the field. The effectiveness of different control methods is
influenced by variables such as the properties of the fuel or
waste, the source operating conditions, flue gas cleaning
technologies employed, and the species of mercury in the
flue gas. In combustion systems, mercury is volatilized
and converted to elemental mercury vapor (Hg°) in the
high-temperature regions of furnaces. As the flue gas is
cooled, mercury is converted to gas-phase ionic (Hg+2) and
particulate-bound (Hg ) forms of mercury.
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"Speciation" is a term used to denote the relative amounts
of Hg°, Hg+2, and Hgp in flue gas. The rate of conversion of
gaseous Hg° to Hg+2 and Hgp is dependent on the tempera-
ture, flue gas composition, and the amount and properties
of entrained particles (fly ash and sorbents). Mercury
speciation is a particularly important variable for flue gas
cleaning because it directly impacts the capture of the
mercury. For example, mercuric chloride (HgCl2) is water
soluble and readily reacts with alkali metal oxides in an
acid-base reaction; therefore, conventional acid gas
scrubbers used for SO2 control are effective in controlling
HgCl2. However, elemental mercury Hg° is insoluble in
water and must be adsorbed onto a sorbent or converted to
a soluble form that can be collected in a wet scrubber. In
incinerators, the flue-gas concentration of chlorine is
substantially higher than that of Hg°, and results in
preferential conversion of Hg° to HgCl2. In coal-fired
combustion units, where concentrations of chlorine are
much lower and SO2 is present, mercury may remain
predominantly in the elemental form.
In the United States, the control of mercury in MWCs and
MWIs is based on the injection of powdered activated
carbon upstream of an electrostatic precipitator or fabric
filter. Current data from EPA's Information Collection
Request (ICR) for coal-fired utility boilers and recent field
tests indicate that significant mercury capture is being
achieved at coal-fired electric utility boilers through
inherent fly ash sorption and collection in existing particu-
late matter (PM) collectors. These data also indicate that
even more substantial capture occurs for systems using
sulfur dioxide (SO scrubbers and post-combustion
nitrogen oxide (NO, controls. Significant additional control
of mercury emissions will require either addition of dry
sorbents upstream of the existing PM controls or will be
achieved through implementation of advanced controls
and strategies for compliance with fine PM, ozone non-
attainment, regional haze and New Source Review require-
ments, as well as efforts undertaken to reduce Toxic
Release Inventory (TRI) pollutants such as hydrochloric
acid (HC1) and sulfur trioxide (SO3). Future development of
optimal mercury and multi-pollutant combustion source
controls will therefore require an improved understanding
of the fundamental processes that influence the species of
mercury emitted, and testing and evaluation of innovative
approaches to capture mercury in an environmentally and
economically acceptable manner. In this regard, several of
the critical'uncertaintiesare:
1. how mercury speciation and capture in combustion
systems is influenced by fuel or waste properties,
combustion conditions, and flue gas cleaning methods;
2. the extent to which modifications in combustion and
flue gas cleaning conditions can cost-effectively reduce
emissions of various mercury species and co-pollutants;
3. how to measure combustion source emissions of
mercury on a continuous basis; and
4. whether mercury contaminated residuals from air
pollution control systems will need to be stabilized
before disposal.
Over the next three to five years, ORD will work with the
Department of Energy (DOE), the United States Geological
Survey (USGS), and private sector organizations to address
the key scientific uncertainties described above. Studies
will be conducted to identify, evaluate, and demonstrate
innovative technological solutions that can cost-effec-
tively reduce mercury emissions from currently unregulated
sources or those for which improved technologies would
significantly reduce the costs to comply with existing
regulations. The relative costs of controlling mercury only
and of controlling mercury in conjunction with other
pollutants such as fine (PM) and fine PM precursors
(sulfur dioxide and nitrogen oxides) will also be quantified.
The four research areas identified below were chosen
based on priorities identified by OAR, OSW, and external
stakeholders; scientific uncertainties (data gaps) that
currently impede implementation of mercury controls for
specific sources; and the potential to reduce control costs.
Research in these areas is critical to support future
regulatory impact analyses, particularly those that include
mercury in a multi-pollutant framework, and to ensure that
viable options are available for all types of boiler configura-
tions and associated operating conditions. In addition,
without adequate data on combustion chemistry and
associated operating conditions, it will be difficult to
develop better technologies and to understand why
existing technologies do not perform consistently in the
field.
5.6.1.3 Prioritized Research Needs
• Improved understanding of managing mercury species
in combustion processes.
• Improved understanding ofperformance and cost of
mercury emissions controls.
• Increased testing and evaluation of mercury continu-
ous emission monitors.
• Improved characterization of, and management
approaches for, mercury controls residuals.
Improved understanding of managing mercury species in
combustion processes. A need exists to determine the
parameters, including chemical and physical mechanisms
and combustion operating conditions, that affect mercury
species emitted from combustion systems, and to identify
potential approaches to capture these species. The
capture of mercury in a pollution control device is depen-
dent on mercury speciation (i.e., the chemical forms of
mercury). A fundamental understanding of the chemical
and physical mechanisms and combustion conditions that
influence the speciation of mercury in a combustion system
is essential to determine the approaches that will provide
30
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effective capture. Specific research planned will: (1)
determine how fuel or waste properties, combustion
conditions (temperatures, residence times, and quench
rates), flue gas composition, fly ash, and sorbent proper-
ties, and flue gas cleaning equipment affect mercury
speciation; (2) evaluate whether mercury speciation can be
controlled by using reagents, catalysts, or adjustments to
the combustion process conditions; (3) identify fly ash,
sorbent, and flue gas properties that lead to high levels of
mercury adsorption and determine whether changing
combustion conditions will enhance adsorption; (4)
determine the solubility of different mercury species as a
function of different scrubber operating conditions
(temperature, dissolved species, and reagents); and (5)
determine the scrubber conditions necessary to convert
Hg° to the easier-to-capture species. NRMRL will conduct
bench- and small pilot-scale research on mercury behavior
and innovative capture methods, and the most promising
innovations will be evaluated on larger pilot-scale facilities.
Improved understanding ofperformance and cost of
mercury emissions controls. A need exists to develop
information on performance and cost of specialized
sorbents, reagents, and control equipment that can be used
to reduce mercury emissions from utility boilers and other
combustion sources. Conventional flue gas cleaning
technologies are not always appropriate for controlling
mercury emissions, and special sorbents, reagents or
equipment must be used for more effective control. The
performance of technologies for controlling mercury
emissions is dependent on a number of factors that include
the effectiveness of sorbents and reagents and the
physical/chemical conditions that determine mercury
capture (temperatures, resident times, flue-gas composi-
tion, fly-ash properties, sorbent concentrations, reagent
concentrations, and the diffusion or mixing of reactants).
Based on the research conducted to characterize mercury
speciation and control mechanisms and develop sorbents,
field tests will be conducted to evaluate the effectiveness
of different equipment configurations, reagents, sorbents,
and process conditions for controlling mercury emissions.
Studies to determine the potential mercury emissions
reductions that can be achieved by technologies currently
used to reduce criteria air pollutants will also be conducted.
Preliminary evaluation of ICR data indicates that technolo-
gies currently in place for control of criteria pollutants
achieve reductions in mercury emissions that range from
less than 10 percent to more than 90 percent. The level of
co-control currently achieved can be increased by applica-
tion of mercury retrofit technologies. Improved mercury
control can also be achieved by methods designed to
increase capture of more than one pollutant. This approach
can utilize the synergisms that accrue through the applica-
tion of multi-pollutant control technologies. The co-
benefits can be maximized by linking mercury control to the
reduction of the other regulated pollutants such as NOx,
and SO2.
Current estimates of mercury control costs using powdered
activated carbon (PAC) injection range from 0.31 to 3.78
mills/kwh depending on the type of coal used and the
control technologies already in place. Engineering cost
studies will be conducted to provide updated estimates of
capital and operating expenses for PAC and innovative
mercury retrofit control technologies. These updated costs
will take into account the latest information available on the
type of coal used and air pollution control systems in
place. As part of this effort, research is planned to develop
the methodology and data required to quantify the
incremental mercury control costs for various multi-
pollutant control options. NRMRL and DOE are coordinat-
ing with utility companies and technology vendors to test
promising mercury and multi-pollutant control technology
options in the field. The DOE has already solicited
proposals. Their main role will be to select the test sites
based on proposals submitted and provide funds for
testing; industry will co-fund by providing the equipment
and power plant upgrades, and NRMRL will play a lead role
in collecting information on mercury emission levels both
before and after the control device. More information on
the activities of DOE and EPRI are discussed in Chapter
4.0. Finally, ORD will work with OAR to evaluate other
mercury control options feasible for the electric utility
industry, such as changes in dispatch patterns and fuel
nix.
Increased testing and evaluation of mercury continuous
emission monitors. A need exists to evaluate the perfor-
mance and application of continuous emissions monitors
(CEMs) to measure total mercury and the species of
mercury present in combustion emissions even at very low
concentrations. The ability to evaluate the performance of
control technologies, determine compliance with regula-
tions, and better characterize source emissions to support
risk assessments requires CEMs that are capable of
accurately and reliably quantifying both total mercury (Hg)
as well as the speciated forms of Hg emitted from combus-
tion sources, particularly at trace levels. Currently, total
mercury CEMs are commercially available and widely used
in Europe and their performance accepted. However,
acceptable performance in the U.S. cannot be assumed, as
pollution control device configurations in the U.S. vary
greatly from those found in Europe. These CEMs are still
susceptible to measurement interferences from combustion
gases such as SO2, hydrogen fluoride, HC1, and NOx. In
addition, most units are not capable of measuring the
particulate-bound mercury component. As a result, PM is
routinely filtered out, and remains unmeasured.
While there are no commercially available units that
directly measure the various mercury species, significant
strides have been made over the last few years. Many total
gaseous mercury CEMs can be used to indirectly measure
mercury species (the elemental and oxidized forms) by
determining the difference between the elemental mercury
and total gaseous mercury. This difference is recognized
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as the oxidized form. Separate mercury measurements are
made before and after the conversion step in order to
calculate the oxidized form ("speciation by difference").
Several vendors are currently attempting to develop a
mercury CEM that is capable of differentiating the species
of mercury. Research is needed to identify the appropriate
methods of measuring total mercury and the mercury
species (the chemical forms of Hg) in combustion system
flue gases. ORD's Environmental Technology Verification
Program is planning to verify CEM performance against
vendors' claims.
Research is needed to: (1) investigate the biases associated
with total and speciated mercury measurements, particu-
larly those associated with particle-bound mercury and the
effects of interferences; DOE is sponsoring research to
investigate sample conditioning techniques that address
bias associated with speciated mercury measurements (by
difference) and reactive paniculate matter; and (2) evaluate
the performance of total and speciated CEMs through both
pilot-scale and field testing. Research also needs to be
performed to determine if one method will work for all
combustion sources or whether different methods must be
used, and evaluate whether continuous measurements of
mercury can confirm the effectiveness of feed limitations
and thereby reduce compliance costs (i.e., prove that
emissions levels have been met without costly sampling of
input stream). NRMRL is working with DOE in this area
and will support field evaluation of the techniques identi-
fied under item 1 above.
Improved characterization of, and management ap-
proaches for, mercury controls residuals. There is a need
to characterize mercury-contaminated residuals from air
pollution control systems and, if needed, determine the
cost and performance of technologies that can stabilize the
residuals before they are sent for land disposal. Use of
sorbent injection technologies to control emissions at
electric power plants typically results in residues, which are
either used as byproducts or are disposed. The total
generation of coal combustion residues in 1998 was~108
million tons, with ~77 million tons landfilled and ~31 million
tons utilized. OSWER has indicated that composition data
characterizing the different residues, as well as data on the
composition of leachate are needed for total and speciated
mercury, arsenic, and other toxics in these residues. These
data are needed for calculating the mass balance flows
associated with the management of mercury-contaminated
residuals from coal-fired power plants.
No information is currently available on the potential life-
cycle environmental burdens resulting from volatilization of
mercury from byproducts and disposed residues. In order
to ensure the mercury is not simply released into soil or
groundwater, or subsequently released in air, research is
needed to: (1) characterize any releases associated with the
residues, and (2) develop ways to correctly manage the
residues, including stabilizing the mercury before it is sent
for land disposal, to prevent any subsequent release of
mercury back into the environment. Research will focus on
those waste management practices that are suspected of
having the greatest potential for release of mercury
including utilization of mercury containing residues in
cement and wallboard production and production, and
application of asphalt. The results from this research will
provide a better set of data characterizing the various
residue types and an improved understanding of the
ultimate fate of mercury in the various practices in use to
manage residuals from coal-fired power plants.
NRMRL will take the lead to synthesize results from the
research described above including data generated by
other federal agencies, academia and industry (ORD does
not plan to conduct research to evaluate improved
techniques to clean coals prior to combustion; however,
results of any research conducted by other federal
agencies or private industry will be included in the
integrated outputs). Concise summaries of technology
costs and performance will be provided to OAR and other
interested stakeholders to assist them in evaluations of
alternative mercury emission reduction options. These
integrated research summaries will include information on
how to control the various forms of mercury emitted and
how integrated combinations of technologies can be used
to simultaneously control mercury and other air pollutants
of concern.
5.6.1.4 Research Results
Results from this research will provide improved data on
the cost and performance of control technologies and other
risk management options capable of reducing mercury
emissions from priority combustion source categories (e.g.
coal-fired utilities). OAR, OW, OSWER, and other Program
Offices will use the data and information from this research
to support regulation development for combustion sources
where the Agency has a statutory responsibility to address
mercury emissions. This work will also help states,
Regions, and the private sector determine how specific
technologies or approaches can be used to meet emissions
standards or voluntary reduction targets that have been
negotiated with EPA.
5.6.1.5 Measures of Success
Researchers hope to advance the following:
• Identification of the combustion conditions that have
the most significant impact on the species of mercury
formed in coal-fired utility boilers.
• Development of innovative mercury and multi-pollutant
control systems that remove 70 to 90 percent of mercury
at the lowest possible costs.
• Identification of viable approaches to measure both
total mercury and species of mercury.
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• Full characterization of the releases or emissions of
mercury from waste management and utilization
practices.
• Completion of successful demonstrations, at full or large
pilot-scale, of innovative options to reduce mercury
emissions from coal-fired utility boilers.
• Development of the most up to date information on the
costs of mercury and multi-pollutant control options to
support regulatory decisions.
• Production of a handbook on mercury controls to
support implementation of regulatory requirements.
This handbook will summarize information on the
relative performance and cost of reducing mercury
emissions using pretreatment approaches, flue gas
cleaning technologies or combinations of these
approaches with other air pollution control systems (co-
control).
5.6.1.6 Preliminary Performance Goals
• By 2003, produce a comprehensive summary report
(capstone report) documenting the performance of
devices used to continuously measure total or species
of mercury.
• By 2004, produce a technical assessment of the life-
cycle implications of mercury-contaminated residues
from air pollution control systems including the cost
and performance of any required stabilization technolo-
gies.
• By 2005, complete comprehensive assessment of the
capability of mercury control technologies and other
risk management options (e.g. fuel switching) to achieve
reductions from 70 to 90 percent in the most cost-
effective manner (lowest $ cost per unit of pollutant
removed).
5.7 RISKMANAGEMENTFORNON-
COMBUST1ON SOURCES
5.7.1 Key Scientific Question
What is the magnitude of contributions of mercury
releases from non-combustion sources; how can
the most significant releases be minimized?
5.7.1.1 Background
While available data on the use and release of mercury in
the non-combustion source category are limited, some
available data indicate the total disposition of mercury by
various segments of this category in the United States. In
1995, this category consumed 436 tons of mercury and
contributed about 13 percent (20 tons) to U.S. mercury
emissions. In the same year, over 12.2 million metric tons of
mercury-bearing hazardous wastes were generated (EPA,
1998f), and an estimated 227 tons of mercury were dis-
posed of in municipal landfills as part of mercury-bearing
solid wastes. (EPA, 1997a)'
Because of the wide variety of sources and difficulties in
measuring mercury emissions, estimates for some U.S.
sources are believed to be low. However, these sources
generally have low stacks or vents (and in some cases
release soluble mercury compounds, such as HgCl2 or even
methylated mercury compounds) that may result in higher
rates of local exposures per unit emissions compared to
combustion sources. The numerous anthropogenic
activities that use mercury produce mercury-bearing
wastes and consumer products (including bulk elemental
mercury) will pose a long-term threat to the environment if
not disposed of properly. On a national scale, the magni-
tude of releases of mercury to soils and water by non-
combustion sources appears relatively small. However,
current and past releases are the sources for local "hot
spots" of mercury contamination, and any significant
releases from these hot spots need to be minimized.
5.7.1.2 Program Relevance
As reflected in the Draft EPA Action Plan for Mercury
(Federal Register, 1998), the Agency proposes to reduce
mercury releases from non-combustion sources using a
number of approaches, including regulations (e.g., Maxi-
mum Achievable Control Technology for chlor-alkali plant
emissions) and promotion of voluntary activities by
industry to reduce mercury use (e.g., mercury takeback
programs). Site- and facility-specific problems are being
addressed by EPA Regional Offices. In some cases,
improved characterization of mercury sources is needed
prior to selecting options for reducing releases. The results
of improved approaches to characterizing and reducing
releases in the U.S. will carry over to the rest of the world,
as evidenced by a number of EPA activities undertaken
with other countries to enhance emissions reductions.
Research described in this section supports a number of
these important Agency activities.
5.7.1.3 Prioritized Research Needs
This section describes major remaining research activities
to manage mercury releases from non-combustion sources,
encompassing all non-combustion activities over the
anthropogenic life cycle of mercury from extraction and
refining through use to disposal. Releases of mercury to
any environmental medium (air, ground or surface waters,
or soil) are included. The scope of this section covers three
phases of non-combustion risk management research:
• Characterization of the mercury life cycle in human
activities (Phase I).
• Improved understanding of mercury releases from
sources and sinks (Phase II).
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• Approaches for minimizing mercury releases from non-
com bust ion sources (Phase III).
While the scope of research activities in this section is
broad, in keeping with the general approach of this
strategy the research in this section will address only the
most significant information gaps. Factors to be used in
determining relative significance include the magnitude and
uncertainty associated with characterizing and controlling
releases to determine their risk, as well as the cost and
effectiveness of characterization and control techniques.
Also, a phased approach of progressively focused, in-
depth studies will be used to maximize the impacts of the
research program. In some cases, work will have to
progress through all three phases. In other situations, the
significance of an issue is well enough understood to
proceed immediately to later phases. For example, ORD
started investigating improved treatment options for
hazardous waste disposal in FY 1999.
Because of the high EPA priority on management of
mercury releases from combustion sources, studies of non-
combustion sources will be limited through at least FY
2002. Therefore, some of the research needs described in
this section may not be addressed until FY 2005 or beyond.
ORD has organized its non-combustion risk management
research program into project areas based on source type.
Research in F Y 2001 and F Y 2002 will focus principally on
source emissions characterization, process waste and
mercury stockpile disposal, and options for reducing
mercury use. During this period, characterizations of the
mercury life cycle in human activities and its associated
mercury releases should help to further focus research in
these areas in FY 2003 through FY 2005. The significance
of mercury from contaminated media such as sediments
and mining residuals should also be better understood by
FY 2002, allowing ORD to plan research activities in these
areas for F Y 2003 through FY 2005.
Characterization of the mercury life cycle in human
activities (PhaseI). There is a need to conduct a prelimi-
nary characterization of the mercury life cycle. The
purpose of this activity is to understand the current flow of
mercury in the United States from production to disposal,
and to identify the significant release points during its life
time. The results of this work will focus further ORD's
releases characterization and control research. It should
also identify human activities that have resulted in areas of
major soils or sediments contamination.
Two activities are currently planned in this area:
• Evaluation of mercury use in the industrial sector to
determine opportunities for reducing environmental
impacts through source reduction;
• A preliminary inventory to re-evaluate releases data and
identify the non-combustion sources with the most
significant releases. The resulting "significant" sources
will be characterized in more detail (see Phase II).
The evaluation of mercury use will update existing models
of mercury flow in United States commerce. Besides
helping to identify source reduction opportunities, it will
also provide the Agency with basic information to create a
supply and demand model for mercury in the United States.
Such a model could be used to determine how economic
and regulatory conditions might alter the flow of mercury in
the United States. Such futuristic scenarios would also be
an important additional contributor to focusing ORD's
mercury research program. Because of the current empha-
sis placed on air emissions sources by the Agency, ORD
initial releases inventory work will start in this area. ORD
will work with the Office of Air and Radiation (OAR) to
update available screening inventories of source emis-
sions, such as that produced in The Mercury Study Report
to Congress. By FY 2002, ORD plans to have conducted
sufficient preliminary evaluations of mercury emissions to
refine research priorities for Phases II and III.
Improved understanding of mercury releases from
sources and sinks (PhaseIJ). A need exists to better
characterize mercury releases to the environment. While
mercury releases are well characterized from some sources,
that is not the case for all. For example, there is uncertainty
about the magnitude of both elemental and speciated
mercury air emissions from some sources that were
identified in The Mercury Report to Congress as having
releases below 10 tons/year. In many cases these uncer-
tainties arise because good sampling or analytical tech-
niques do not exist. In other cases, sufficient releases data
have not been collected. ORD mercury releases character-
ization studies are intended to develop better sampling or
analytical techniques on a source-specific basis, and to
sample a very limited number of sources to better charac-
terize their emissions. This releases characterization
research will be carried out on a particular source type if
sufficient data already exist to show it to be a potentially
significant source, or if the results of Phase I so indicate.
NRMRL is currently targeting emissions characterization
studies from: (1) mercury-cell chlor alkali plants (MCCAPs)
and (2) municipal landfills. MCCAPs were identified
because of the large discrepancy between their annual
mercury makeup (about 160 tons/year) and their estimated
7.1 tons/year in mercury releases (EPA, 1997a). Mercury
emissions from municipal landfills will be studied as part of
an Agency program addressing PBT emissions from
municipal landfills. While existing data suggest that
landfills may not be a major source of inorganic mercury,
the data also suggest that methylated mercury compounds
may be emitted. Other sources of mercury air emissions
that may require characterization include the oil and
petroleum industry. The significance of their emissions will
be considered along with others from non-combustion
sources in the preliminary emissions inventory work of
Phase I to determine if emissions characterization research
is needed for them in Phase II.
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Mercury releases can also occur in the form of solid waste
and water effluent streams. Mining effluents are believed
to be the most significant mercury effluent source, causing
regional contamination problems. Mercury-bearing
effluents from mining appear to cause significant sediments
contamination and associated fish advisories in receiving
rivers and lakes, particularly in the western United States.
Preliminary studies will be conducted to better characterize
mercury releases from mines in order to determine whether
the problem is significant enough to warrant control
research. ORD will continue to work with the Mercury
Task Force (MTF) to determine other significant mercury
effluent sources.
Waste streams pose more uncertainties. It is difficult to
characterize mercury-bearing wastes, and how they release
mercury under the range of environmental conditions
found in disposal facilities. Because of this, and as part of
its support of the EPA Office of Solid Waste (OSW)
rulemaking to revise the Land Disposal Restrictions (LDRs)
treatment standards for mercury-bearing wastes, especially
"high subcategory" mercury wastes (i.e., wastes contain-
ing over 260 ppm total mercury), ORD is evaluating
improved characterization techniques for mercury in
wastes. Both sediments and soils can be sources of
mercury releases to air or surface waters. (Ground water is
not viewed as a significant exposure pathway). Sediments
are a significant sink for air- and water-borne mercury
releases. Sediments are also host to the base of the food
web that extends through aquatic organisms to land-based
wildlife and humans. There are also a number of sites with
significant contaminated mercury in soil, and while
elemental mercury in soil is not highly soluble, it may be
volatilized, or methylated and enter the food chain.
Approaches for minimizing mercury releases from non-
combustion sources (PhaseIII). There is a need to identify
alternate approaches for minimizing mercury releases.
Mercury releases can be minimized by reducing the use of
mercury or by use of end-of-pipe controls, including waste
treatment. NRMRL will study both approaches, focusing
on major release sources. Source reduction opportunities
will be identified in the mercury-use study in Phase I.
Selections will be based on release potential, industry
interest in voluntary reduction, and other factors. For
these selected sectors, ORD will conduct research to
advance the reduction of mercury use. This research, done
in collaboration with industry where possible, will include
application of life cycle analysis (LCA) tools and studies of
innovative source reduction processes.
Sources requiring mercury control research will be identi-
fied based on the magnitude of the release, availability of
cost-effective control techniques, and Agency priorities.
For example, if releases of mercury are significant from
MCCAPs or mining, then control research may be required
because cost-effective means of controlling non-point
source releases is often difficult. Treatment technology
research on hazardous wastes bearing high concentrations
(>260 ppm) of mercury is an OSW priority because they are
currently investigating alternatives to incineration and
retorting. The research needs, collaboratively identified
with OSW, include improved waste characterization and
alternative technology research and demonstration.
The ultimate disposal of mercury stockpiles is also of
concern. Large stockpiles already await disposal. For
example, The Department of Defense (DOD) currently
manages a mercury stockpile of approximately 4,400 metric
tons. The total amount of stockpiled mercury in the United
States will be increasing as the number of federal, state and
local programs to reduce mercury use and to recycle
mercury products increase. Environmentally safe disposal
alternatives for elemental mercury have not been fully
evaluated in terms of long-term effectiveness and cost.
ORD will work with the EPA Mercury Task Force and
outside stakeholders to determine major research needs
and to address those where expertise is available.
Three approaches are available for the management of
mercury in sediments: capping, in-situ methods, and
dredging followed by confinement or treatment. Natural
processes affecting Hg in this environment must also be
understood. NRMRL has an established contaminated
sediments research program and many of its research
findings for metals are applicable to mercury. However,
research is needed on in-place management of mercury-
contaminated sediments that focuses understanding and
enhancement of processes that sequester mercury from the
food web. These processes include physical disruption of
the exposure path (e.g., clean sediment deposition),
chemical alteration of the mercury to less bioavailable or
biotoxic forms, and biological transformation or sequestra-
tion. Particular emphasis will be given to disrupting the
formation of methyl-mercury.
Research on remediation options for soils contaminated
with mercury is a lower relative priority, although
remediation of these sources must ultimately be addressed.
Contaminated soils remediation may be of high priority on
a site-specific basis. Remediation options for such sites
are under development by others, such as DOE, and
should continue. Whenever possible, information on
remediation options for soils should be collected during
mercury remediation/treatment research on waste streams,
mining, and contaminated sediment, and during more
broadly-scoped remediation research for metals in soils.
5.7.1.4 Research Results
Results from this research will contribute to an improved
understanding of mercury releases from non-combustion
sources, and where appropriate, sinks (e.g., contaminated
sediments, abandoned gold mining sites). While emissions
from coal-fired utilities and other combustion sources are
fairly well understood, this is not the case for other sources
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of mercury. The Program Offices, Regions, and states will
all benefit in terms of regulatory and voluntary actions for
mercury with a better understanding of the releases from a
variety of sources. Work will also be targeted at ap-
proaches that minimize mercury releases into the environ-
ment, including the ultimate disposition or retirement of
excess metallic mercury stocks.
5.7.1.5 Measures of Success
As indicated above, research on the non-combustion risk
management research area starts at a modest level, likely
expanding in FY 2004 as the need for combustion risk
management research declines. The ability of ORD to
accomplish all the research described in this section is
resource dependent and will likely need to continue past
FY 2005 in order to reach the measures of success de-
scribed below. In addition, Phase I research during the
early years of the program may identify higher priority
research needs, and therefore some research activities
described here could be dropped altogether. Conse-
quently, the measures of success described below are
those currently identified for priority research needs, but
these measures are subject to change as our understanding
of non-combustion mercury releases grows.
1. Characterization of the mercury life cycle in human
activities (Phase I)
• Assessment of anthropogenic mercury use to identify
major opportunities for reducing use and/or releases.
• Assessment of the relative significance of mercury
emissions from anthropogenic sources in the United
States.
2. Improved understanding of mercury releases from
sources and sinks (Phase II)
• Identification and/or evaluation of technologies and
techniques that provide improved MCCAP facility
emissions measurements.
• Improved characterization of air emissions from priority
source categories, such as MCCAP, landfills and oil and
gas processing facilities.
• Identification of mining waste types that contribute
most to mobile mercury.
3. Approaches for minimizing mercury releases from non-
combustion sources (Phase III).
• Improved understanding of the effectiveness and cost
of vendors' innovative technologies for control of air
emissions from high priority source categories.
• Assessment of the effectiveness, cost, and environmen-
tal impacts of solidification/stabilization processes as
applied to mercury-bearing hazardous wastes.
• Recommendations for improved techniques for deter-
mining the mobility of mercury in various hazardous
waste treatment residuals.
• Evaluation of several pollution prevention approaches
for reduction of mercury use, and determination of the
reduction in adverse environmental impacts.
• Improved understanding of the processes that control
mercury transport and re-transformation in sediments.
• Development and/or evaluation of three technologies to
control mercury transport or bioavailability at aban-
doned mining sites.
• Assessment of the options for ultimate disposal of
mercury stockpiles.
5.7.1.6 Preliminary Performance Goals
Current GPRA Annual Performance Goals (APG) for this
program reflect the phases of activities of the program (FY
2003 and FY 2006 APGs) and the anticipation that the
program should take about 10 years to complete. The APGs
are:
• By 2003, provide technical resource documents to
public and private decision makers and other stakehold-
ers on the magnitude of releases of mercury from non-
combustion sources and recommend methods for
characterizing emissions for priority sources.
• By 2006, provide technical resource documents to
public and private decision makers and other stakehold-
ers on options for cost-effectively reducing releases
from priority non-combustion sources including "low
tech" approaches for reducing mercury emissions.
• By 2007, provide technological transfer of control and
mercury reduction technologies for combustion and
non-combustion sources.
• By 2009, provide an authoritative set of risk manage-
ment options to public and private decision-makers and
other stakeholders for priority non-combustion sources
of mercury releases to the environment.
5.8 ECOLOGICAL EFFECTS AND
EXPOSURE
5.8.1 Key Scientific Question
What are the risks associated with methylmercury
exposure to wildlife species and other significant
ecological receptors?
5.8.1.1 Background
Recent scientific progress has led to a greatly improved
understanding of mercury fate and transport in the
environment and its toxicity to a wide range of ecological
receptors. This work has focused attention on the aquatic
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environment and, in particular, on consumption of methyl-
mercury contaminated fish by fish-eating birds and
mammals. A review of this material is provided in "An
Ecological Assessment for Anthropogenic Mercury
Emissions in the United States," Volume VI of the Mercury
Study Report to Congress'(EPA, 1997a). The report
primarily assessed the impacts of mercury and methylmer-
cury on wildlife and did not focus on fish or other biota.
Despite this progress, however, substantial scientific
uncertainties remain that limit efforts to characterize the
ecological risks associated with anthropogenic mercury
emissions. The research areas prioritized below reflect
EPA's need to assess the risk of methylmercury to fish-
eating wildlife and to calculate water-based wildlife criteria
for mercury that are protective offish-eating wildlife
populations. The Agency recognizes that this
prioritization could change substantially as new informa-
tion about mercury exposure and effects becomes avail-
able. In many cases it is difficult, and sometimes counter-
productive, to consider chemical effects apart from
exposure. The emphasis of this effort is on research needs
for ecological effects assessments and ecological risk
assessment. Section 5.5 focuses on the fate and transport
of mercury. Section 5.5.1.3 includes research on aquatic
and terrestrial transport, transformation, and fate, and will
supply exposure data concerning ecological endpoints.
Results from the effects and exposure research, along with
distributional assessment methods, will produce a state-of-
the-art ecological risk assessment for mercury.
5.8.1.2 Program Relevance
Mercury pollution of aquatic systems is a national problem.
At the end of 1998, fish consumption advisories due to
unacceptable levels of mercury existed in 40 States. In
some cases, these advisories can be traced to point
sources of mercury. Increasingly, however, non-point
source mercury contamination has resulted in large-scale
pollution of entire ecosystems, with possible impacts on
both humans and wildlife. Perhaps the best known example
is that of the South Florida Everglades, which is home to
the endangered Florida panther. High levels of mercury
and methylmercury in tissues of deceased animals have led
to the suggestion that methylmercury is a contributing
factor in the decline of the panther population. It is the
responsibility of EPA's Regional Offices to deal with such
problems. Seeking technical assistance, the Regions have
engaged the Office of Research and Development (ORD),
the Office of Water (OW), the Office of Air Quality
Planning and Standards (OAQPS), and others, to address
this concern.
EPA has the responsibility under the Clean Water Act
(Section 304(a)( 1)) to develop water quality criteria that are
protective of wildlife that may be exposed to chemical
pollutants in water. The first effort to develop a wildlife
criterion for mercury was undertaken by OW in support of
the Great Lakes Water Quality Initiative (GLI). The GLI was
promulgated as a rule, and as such, constitutes a powerful
legal mandate. States in the Great Lakes basin have either
submitted or are drafting strategies for compliance with the
GLI. EPARegions (Regions II, III, and V) that adjoin one or
more of the Great Lakes are primarily responsible for
implementation of the GLI, including the wildlife criteria for
mercury. Uncertainties regarding wildlife exposures to
methylmercury and the subsequent effects of those
exposures have greatly complicated these efforts. This
research area will serve to strengthen the scientific
credibility of water quality criteria for mercury and proce-
dures for implementing those criteria in watersheds
throughout the Nation.
5.8.1.3 Prioritized Research Needs
The major research needs are identified below in order of
their relative priority. Each is accompanied by a brief
narrative to describe the type of work required to address
these needs.
• Improved understanding of methylmercury toxicity
effects on avion and mammalian wildlife.
• Refined ecological assessments for avion and mamma-
lian wildlife risks.
• Improved understanding of ecological impacts of
methylmercury on avian and mammalian wildlife.
• Improved understanding of ecological impacts of
methylmercury on non-avian and non-mammalian
species.
• Identification of interactions among methylmercury
and other chemical and non-chemical stressors on all
ecological receptors.
Improved understanding of methylmercury toxicity
effects on avian and mammalian wildlife. A need exists
for controlled laboratory studies of methylmercury
disposition and effects in wildlife species or appropriate
surrogates. Current procedures for calculation of a wildlife
criterion (WC) for mercury are based on an extremely
limited toxicity data set. Moreover, in the calculation of a
wildlife reference dose (RfD) for methylmercury, there is a
need to use several uncertainty factors (e.g., species-to-
species, LOAEL-to-NOAEL), each of which is supported
by very limited data. Research should be conducted to
characterize the kinetics of methylmercury uptake and
disposition, and the importance of hepatic demethylation
as a route of elimination. Additional research is needed to
develop and refine assessments of risk based on mercury
and methylmercury residues in the tissues of exposed
wildlife and their prey. Tissue residue-based assessments
have the potential to avoid many uncertainties associated
with assessing mercury and methylmercury exposure.
However, research is needed to support the development
of reliable tissue-residue response relationships, including:
identification of critical target tissues, assessment of
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interspecies and intraspecies differences in sensitivity; and
the development of Physiologically-Based Pharmacokinet-
ics (PBPK) dosimetry models for sensitive and highly
exposed species.
Refined ecological assessments for avion and mamma-
lian wildlife risks. The research above will contribute to
improve assessments of mercury risk to wildlife and other
ecological receptors. It is possible, however, to identify
research that focuses directly on the risk assessment
process as a means of addressing specific problems. Given
the relatively small number of avian and mammalian wildlife
species that prey heavily on fish, it is reasonable to collect
species-specific information that would lead to improved
exposure characterizations. This would include character-
izations of exposure variability due to seasonal changes in
location and dietary choice. In risk characterization,
probabilistic and distributional methods must be applied to
both exposure and effects information. Analyzing the
distribution or range of a given parameter (i.e., toxic effects,
fish size, food consumption) will reduce uncertainty. For
example, point estimates of effect could be replaced by
information that would permit the calculation of effects
benchmarks and statistical confidence limits.
Revising laboratory experimental designs to produce dose-
response curves with EC10, EC20 values will enhance the
use of probabilistic methods. Existing ecological risk
assessment methods are, in general, poorly adapted for use
with compounds that bioaccumulate and are
biotransformed. New assessment methods must be
developed to accommodate these factors, perhaps in
concert with more site-specific or residue-based regulatory
procedures. It is expected that future exposure research
efforts will be focused on identification of aquatic systems
that have characteristics for significant methylmercury
production. This work should be complemented by
research on other factors that contribute to variability in
bioaccumulation of methylmercury by fish. Bioenergetics-
based bioaccumulation models for fish must be developed
to provide probabilistic residue estimates within and
among trophic levels.
Improved understanding of ecological impacts of
methylmercury on avian and mammalian wildlife. Using
a "weight of evidence" approach, the authors of the
Mercury Study Report to Congress reached the conclusion
that mercury originating from airborne sources has had an
adverse impact on several avian and mammalian wildlife
species. Field data required to confirm or refute this
suggestion are, however, lacking. A need exists to conduct
field research on wildlife species. This research would be
complementary to the laboratory studies described
previously. Critical questions that would be addressed by
this work include: (1) are there species that, because they
possess specific attributes, could function as sentinels for
mercury contamination? (2) do field data support projec-
tions of increased risk to wildlife living in proximity to
mercury emissions sources? and, (3) can population
attributes (e.g., age-class structure) be used to indicate
adverse effects on individuals? A critical question for
establishing a WC value for mercury is whether a popula-
tion of animals can withstand adverse effects on a limited
number of individuals. Population models for relevant
species must be developed to predict the probability of
localized extinction due to impacts on critical population
parameters (e.g., reduction in the per capita growth rate due
to reproductive effects), as well as time-to-recover under
different exposure reduction scenarios. Finally, it is
important to determine whether sublethal exposures to
methylmercury can contribute to the demise of endangered
wildlife species.
Improved understanding of ecological impacts of
methylmercury on non-avian and non-mammalian
species. Based largely upon exposure considerations, it
may be concluded that piscivorous avian and mammalian
wildlife species are most at risk from adverse effects of
environmental mercury. This analysis presumes, however,
that the toxicological sensitivity of all animals to mercury
(on a delivered dose basis) is approximately the same. The
possibility exists that there are animals that, because of
increased sensitivity, experience adverse toxic impacts at
relatively lower tissue-residue burdens. Research focused
on early life stages offish has revealed toxic impacts at
waterborne methylmercury concentrations previously
thought to have no effect on fish. This work should be
expanded and similar research conducted on other key
aquatic species. Additional work is needed to evaluate
mercury and methylmercury toxicity to some terrestrial
species, especially those that inhabit forest soils and soil
drainages. A second possibility is that there are non-
wildlife aquatic or terrestrial species that, because of
unusual bioaccumulation or food web relationships,
experience mercury exposure comparable to that of
piscivorus wildlife.
Identification of interactions among methylmercury with
other chemical and non-chemical stressors on all
ecological receptors. Mercury often co-occurs with other
chemical stressors, and in particular with compounds that
tend to bioaccumulate in aquatic biota, including polychlo-
rinated biphenyls (PCBs) and2,3,7,8-tetrachlorodibenzo-p-
dioxin (TCDD). In mixture studies with mink, methylmer-
cury and PCBs acted together, resulting in toxic effects
greater than those that could be attributed to either
chemical individually (EPA, 1997a). Additional studies of
this type are needed to define the nature of these chemical
interactions. Field research is also required to investigate
the potentially modifying effects of both chemical and non-
chemical stressors. Perhaps the best example to date is
that of the Florida panther. While it can be shown that
mercury residues in dead panthers exceed levels found in
experimentally intoxicated cats, a multitude of other factors
complicate any assessment of risk. Included among these
factors are habitat fragmentation and a lack of genetic
diversity.
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5.8.1.4 Research Results
Results from this research will be used by NCEA in refined
mercury ecological risk assessments that will support
future policy decisions on safe mercury levels for fish,
birds, and other animals. Data that are developed will
contribute to an improved sensitivity analysis and assist in
reducing uncertainty in a number of areas pertinent to
mercury effects and exposures in ecosystems. Using these
refined risk assessments will help OW provide more
informed guidance on methylmercury in water bodies. This
work will also assist States in making decisions on action
levels for mercury total maximum daily loads (TMDLs).
5.8.1.5 Measures of Success
Researchers hope to advance the following:
• Successful characterization of the toxicokinetics and
toxicodynamics of methylmercury in piscivorous avian
and mammalian wildlife.
• Development of probabilistic ecological impact assess-
ment procedures for mercury that explicitly recognize
relevant natural processes.
• Characterization of the impact of methylmercury on
piscivorous wildlife populations at local, regional, and
national scales.
• Reduction in the uncertainty in evaluation of potential
adverse effects on fish.
• Evaluation of the potential for adverse impacts on fish
and other non-avian, non-mammalian ecological
receptors.
• Identification and characterization of important interac-
tions of mercury with other environmental stressors.
5.8.1.6 Preliminary Performance Goals
GPRA performance goals have been identified for the
ecological effects and exposure research area based on the
above Measures of Success. They are preliminary in nature
and will be revised and adjusted as part of the implementa-
tion of the Mercury Research Strategy. A preliminary set
of performance goals is offered below. The performance
goals are:
• By FY 2003, prepare a report characterizing the
toxicokinetics and toxicodynamics of methylmercury in
avian species.
• By FY 2005, prepare a report on regional variability
factors leading to a probabilistic ecological risk assess-
ment on methyl mercury.
• By FY 2007, conduct a regionally based probabilistic
ecological risk assessment of the effects of methyl
mercury on representative avian and wildlife species.
5.9 HUMAN HEALTH EFFECTS AND
EXPOSURE
5.9.1 Key Scientific Question
What critical changes in human health are associ-
ated with exposure to environmental sources of
methylmercury in the most susceptible human
population? How much methylmercury are humans
exposed to, particularly women of child-bearing age
and children among highly-exposed population
groups; what is the magnitude of uncertainty and
variability of mercury and methylmercury
toxicokinetics in children?
5.9.1.1 Background
Health Hazards
The initial step in the risk assessment process is identifica-
tion of health hazards. Earlier reference doses (RfDs) for
methylmercury were based on neurological changes in the
adult. In 1994, EPA announced a new RfD based on
methylmercury's adverse effects on children's neurological
development. Other federal agencies (e.g., FDA) continue
to base their regulatory activities on effects in adults or
have developed assessments (e.g., ATSDR's Toxicology
Profile on Mercury [ATSDR, 1999]) aimed at a fetal
protective dose based on epidemiological studies of other
populations. Between 1995 and 2000, deliberations have
focused on the appropriateness of specific epidemiological
investigations for risk assessment. Following an FY 1999
Congressional budget appropriation for the National
Academy of Sciences (NAS) to conduct a study on
toxicological effects of methylmercury, a report was
released from the NAS in July 2000 (NRC, 2000). This effort
involved a review of the health research on mercury
conducted since the completion of the Mercury Study
Report to Congress released in 1997. The NAS
Committee's report recommended the following:
• That the value of EPA's current RfD for methylmercury,
0.1 micrograms per kilogram of body weight per day, is a
scientifically justifiable level for the protection of public
health.
• Developmental neurotoxicity of methylmercury is the
critical endpoint for setting an RfD, and the Faroe
Islands study should be used as the critical study for
the derivation of the RfD.
• That estimates of a benchmark dose lower bound
(BMDL) of 58 parts per billion (ppb) of mercury in cord
blood (corresponding to a BMDL of 12 parts per million
[ppm] of mercury in hair) is a reasonable point of
departure for deriving the RfD.
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• To calculate the RfD, the BMDL should be divided by
uncertainty factors that take into consideration biologi-
cal variability when estimating dose and methylmercury
database insufficiencies. An uncertainty factor of at
least 10 was supported by the NAS report.
• The NAS report recommended additional investigation
into the following areas:
1. The impact of methylmercury on the prevalence of
hypertension and cardiovascular disease in the
United States. Likewise, reproductive effects of
methylmercury exposure are not fully understood.
2. The relationships between low-dose exposure to
methylmercury throughout the life span of humans
and animals and carcinogenic, reproductive, neuro-
logical, and immunological effects.
3. The potential for delayed neurological effects
resulting from mercury remaining in the brain years
after exposure.
4. The emergence of neurological effects later in life
following low-dose prenatal methylmercury exposure.
5. The mechanisms underlying methylmercury toxicity.
Dose-Response Assessment
The NAS report (NRC, 2000) recommended that an
uncertainty factor of at least 10 be used when developing
an RfD from a BMDL. The committee recommended that an
uncertainty factor of 2 to 3 be applied to a central tendency
estimate of dose derived from maternal hair, or a factor of
about 2 be applied to a central tendency estimate of dose
derived from cord blood to account for interindividual
pharmacokinetic variability in dose reconstruction. This
recognized variability is based on the current understand-
ing of person-to-person variability among adults in
toxicokinetics of methylmercury. Because the developing
nervous system is considered the critical endpoint for
development of an RfD or equivalent values (e.g., ATSDR's
Minimal Risk Level), there is a need for additional data on
toxicokinetics and variability in toxicokinetics in the
pregnant woman/fetal pair. Most of the available data were
developed during studies of adults, especially adult males.
Pregnancy is known to introduce differences in the kinetics
of methylmercury.
The adverse effects of methylmercury on
neurodevelopment continues postnatally (e.g., myelination,
synaptogenesis, and glial cell formation). These pro-
cesses, particularly myelination, continue for a number of
years postnatally making the young child, as well as the
fetus, vulnerable to developmental changes caused by
methylmercury exposures. Methylmercury is known to be
excreted in breast milk making the nursing mother/infant
pair an additional sensitive population. Additional data to
identify the range of variability in estimates of maternal
dose and the infant dose produced by these exposures is
needed. Likewise, the kinetics of methylmercury in children
are fundamentally not known. As noted above, young
children may have additional health changes beyond those
recognized among adults.
Whether or not similar doses in adults and in children
produce similar nervous system responses remains to be
evaluated. Existing data from the poisoning outbreaks in
Iraq and in Japan showed that children will develop the
same symptoms of methylmercury poisoning similar to
those developed by adults. It is unclear if children develop
these responses at lower or higher doses of methylmercury
than those which damage the adult nervous system.
Likewise, additional research is needed to determine if there
are additional endpoints, specific to postnatal exposure
during childhood, associated with increasing exposure to
methylmercury. Toxicokinetic models for methylmercury
are available for adults. The Mercury Study Report to
Congress indicated that research was needed to under-
stand mercury and methylmercury partitioning in children
from a toxicokinetic basis. Further studies offish intake
and methylmercury exposure among children were also
cited as a research need.
Interactions with Other Chemicals, Age, and/or
Forms of Mercury
Evaluation of data from the three major epidemiological
studies (the Faroese, the Seychellois and the New Zealand
cohorts) has been made more complex because methylmer-
cury exposures occur from ingestion offish. Fish contain
chemicals that are beneficial to development (e.g., the
omega three fatty acids) and others that are adverse to
neurodevelopment (e.g., PCBs, other persistent
bioaccumulative toxics such as dioxins). The understand-
ing of how co-exposure to either the beneficial or adverse
effects of these other chemicals is particularly limited in
estimates of dose-response relationships. Initial data also
reveal that prenatal exposure to mercury vapor causes
alterations in both spontaneous and learned behavior in
rodents. Co-exposure to methylmercury at levels (which by
themselves did not alter these functions) served to
potentiate these deficits when exposure to mercury vapor
and methylmercury were combined. Additional research to
evaluate the impact of co-exposures to mercury vapor (as
occur from dental amalgams) and methylmercury from
dietary consumption of fish are needed.
The third major area of interaction is between methylmer-
cury exposures and age-associated changes. The NAS
Committee reviewed preliminary data on the potential
effects of early-developmental exposure to methylmercury
on the functional status of aging animals. Data on
occurrence of symptoms of survivors of Minamata disease
indicated that health risks of methylmercury exposure
could last a lifetime and may become exacerbated during
the process of normal aging. Consequently, research is
needed to determine the long-term implications of the
neuropsychological and neurophysiological effects of low-
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level methylmercury exposures. These studies should
focus on issues that include:
• Critical periods for methylmercury effects: in utero or
postnatal.
• Low-level dose-response relationships.
• Methylmercury demethylation in the brain following
early methylmercury exposures.
• Synergistic effects of early methylmercury exposure and
mercury vapor exposures.
• Neurodegenerative disorders related to methylmercury
exposures.
The NAS report also described recent studies that found
associations between exposure to methylmercury and
impairments in the immune, reproductive, and cardiovascu-
lar systems. Both prenatal and postnatal exposures to
methylmercury have been associated with immunological
and cardiovascular changes. Levels of methylmercury
exposure associated with these effects are as low as those
producing adverse neurodevelopmental effects. In some
cases, the exposures are even lower than those producing
neurodevelopmental changes. Research using animal
models and human populations having chronic, low-dose
exposures to methylmercury is needed.
Although the developing nervous system is more sensitive
to methylmercury than is the adult nervous system, the
NAS report also questioned long held interpretations of
blood and hair concentrations of methylmercury associated
with adverse neurological effects. Recommendations on
tolerable exposures for adults (e.g., EPA's pre-1994 RfD of
0.3 micrograms per kilogram of body weight per day, FDA's
tolerable exposures, and the World Health Organizations
[WHO] limits) are based on the assumption that
paresthesias are the critical effect. Research carried out in
the past decade have identified adverse effects (including
changes in visual field, neuromotor disturbances, visual
and auditory conduction velocities) at exposures less than
those associated with paresthesias. Additional analysis of
dose-response to methylmercury among adults is needed.
Human Exposures
As part of the discussions on the risk characterization for
methylmercury, it was determined that young children are
exposed to higher doses of methylmercury than are adults
(e.g., approximately 1.5- to 2-fold or higher on a body-
weight basis) (EPA, 1997a). Development of the nervous
system postnatally includes processes (among others,
myelination) that are adversely affected by methylmercury;
however, it is uncertain how different exposure-response is
for the young child in comparison with the fetus or the
adult. Children may have different patterns of tissue
distribution of mercury and methylmercury (i.e., biokinetic
patterns) than adults. For these reasons, determining the
dose-response to postnatal mercury and methylmercury
exposures among children is critical.
Consumption offish and marine birds and mammals
represents more than 95 percent of the human intake of
methylmercury. Within the United States, individual
consumption of fish and seafood is highly variable.
Approximately 1 to 2 percent of the U.S. population report
eating fish daily, whereas about 10 percent rarely consume
fish. The Mercury Study Report to Congress (EPA, 1997a)
conducted extensive analyses of fish consuming habits
and patterns among the general U.S. population and high-
risk populations. To improve the human-exposure estimate
on the basis of surveys of fish consumption, more study is
needed within both the general population and high-end
fish consumers. This work would examine specific
biomarkers of mercury and methylmercury exposures (e.g.,
blood-mercury concentrations and hair-mercury concentra-
tions).
Part of a strategy to meet the need for biomonitoring for
mercury in the general population will be met by inclusion
of blood and hair mercury analyses in the fourth National
Health and Nutrition Examination Survey (NHANESIV).
This survey will be large enough to produce estimates of
the upper percentiles of mercury tissue levels in the general
populations of women of child-bearing age and children.
The survey will include dietary questions on type and
frequency of fish consumption. Due to its statistical
design, however, it will not be able to estimate the distribu-
tion of hair and blood mercury levels in highly exposed
sub-populations including: Alaskan Natives, some Native
American tribes, and people of Asian descent, as well as
subsistence and sport fishers and their families, and others
who consume large amounts offish (e.g., some following
"health conscious" diets). While data from similar popula-
tions in Canada will be useful in this connection, research
is needed to fill this data gap because the Canadian data
are largely focused on groups such as Native Canadians
and subsistence fishers in remote locations.
5.9.1.2 Program Relevance
The practical importance of a separate pediatric RfD results
from higher exposures (on a micrograms per kilogram of
body weight per day basis) to methylmercury among
children rather than adults. If children are both vulnerable
and more highly exposed relative to body weight than are
adults, children as well as the maternal-fetal pair are an
important subpopulation. Identifying of which is of
greatest concern includes factors such as the size of the
population, severity of the effect, and relative vulnerability.
Although the RfD for the young child may not be very
different from an RfD that is protective of the fetus, policy
statements would need to address the much higher intake
(on a 0.1 micrograms per kilogram of body weight per day
basis) of the young child. If research subsequently
demonstrates that additional organ systems (e.g.,
immunotoxiocity) are adversely affected at lower doses of
mercury than is the case for neuro-developmental and
neuro-behavioral changes, it may be necessary to revise
the RfD to protect against immunotoxiocity. Likewise, it
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may be of overall importance to understanding at-risk
populations and to reassess what hair and blood mercury
levels are associated with lower exposures than those
producing paresthesia, long held to be the most sensitive
adverse effect in adults.
Estimating the size of the "at risk" human population for
methylmercury exposure requires data on how much
methylmercury people consume from fish and seafood.
Data on geographically determined variability in the
concentrations of methylmercury in fish and seafood are
critical to estimating local impacts of control technologies
and pollution prevention efforts. This information also
provides a baseline against which the impact of future
environmental interventions can be assessed. In particular,
there is controversy concerning the size of the U.S.
population exposed at levels comparable to those in
ongoing studies of fish-eating and wildlife-eating popula-
tions.
The Children's Health Executive Order 13045 (Federal
Register, 1997) requires consideration of children as an "at
risk" population. It is known that children experience one-
to-two times higher exposures (on a body-weight basis) to
methylmercury at comparable concentrations of methylmer-
cury in fish. Because the nervous system continues to
develop during at least the first six years of life, post-natal
exposures to methylmercury may damage the nervous
system after birth. It is not known whether young children
are more like fetuses or adults with respect to CNS-based
methylmercury toxicity. This combination of higher
exposures and uncertainty with respect to vulnerability
makes research on exposures, toxicokinetics, and effects of
methylmercury on children a high priority.
5.9.1.3 Prioritized Research Needs
• Improved understanding of mechanisms of developmen-
tal netirotoxicity from methylmercury.
• Improved understanding of persistent and delayed
neurotoxicity resulting from developmental exposures
to methylmercury.
• Identification of impacts from aggregate exposures and
synergistic effects ofmethylmercury and other pollut-
ants.
• Improved understanding of the modulation of immune
system response from methylmercury exposure.
• Improved understanding of the effects on cardiovascu-
lar function as a result ofmethylmercury exposure.
• Biological monitoring for model development and
improvement.
• Development of toxicokinetic data on methylmercury
tissue distribution.
Improved understanding of mechanisms ofdevelopmen-
tal neurotoxicity from methylmercury. A need exists to
understand the mechanisms of developmental neurotoxic-
ity. While methylmercury is a well-recognized developmen-
tal neurotoxicant in humans and animals, the critical
mechanism(s) are still ill-defined. An improved understand-
ing of the mechanisms of methylmercury's developmental
neurotoxicity should be linked to exposure data in the form
of biokinetic models, in order to provide an improved
framework for the design of biologically based dose-
response (BBDR) models. These models would need to
include reliable predictions of adverse effects following
prenatal, postnatal, and perinatal exposure scenarios.
Improved understanding of mechanisms of developmental
neurotoxicity following exposure to mercury and methylm-
ercury could greatly enhance interspecies extrapolation in
the risk assessment of this environmentally persistent
pollutant. It is necessary to understand and characterize
children's risk because no readily available population
exists for postnatal-only exposures. Mechanistic modeling
of methylmercury-induced developmental neurotoxicity is
predicated on the current and continuing research both in
humans, in vivo animal models, and in vitro models where
exposure and effects have been determined. This research
provides the unique opportunity to expand understanding
beyond theoretical models based upon developmental
mechanisms of action for experimental data, and provide
some predictability of effects following actual low-level
exposures in developing humans.
Mechanistic understanding of methylmercury's develop-
mental neurotoxicity has significant implications for other
compounds and should help to define what developmental
processes, endpoints, and time points may be especially
sensitive to developmental perturbation. In addition,
experimental evidence suggests that the effects of mercury
and methylmercury exposure on the development of the
nervous system and immune system may involve some
common mechanisms (neurotrophic factors and cytokines).
Mechanistic understanding will be highly important in
determining the duration of exposure that is associated
with adverse neurodevelopmental effects. Specifically,
current concepts of RfDs are that these levels are safe if
consumed over a lifetime. However, developmental
windows of vulnerability are such that far shorter time
periods (i.e., days, weeks) maybe highly significant.
Consequently, developmental RfDs may be far more briefer
than life-time exposures. Mechanistic understanding will
also contribute to clarifying co-exposure to other
neurotoxicants, especially inorganic mercury, may need to
be considered in determining tolerable exposures to
methylmercury.
Improved understanding of persistent and delayed
neurotoxicity resulting from developmental exposures to
methylmercury. Another area of concern is the onset or
exacerbation of neurological deficits in aging populations
exposed in utero or as children. There are indications of
this in the follow-up studies of the Minamata population
wherein there is evidence that neurological dysfunction
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among people who have been exposed to methylmercury
becomes exacerbated with aging. This heightened
diminution of function is greater than that attributable to
either age or methylmercury exposure alone. Animal
studies lend support to the conclusion that methylmercury
can have delayed effects that are uncovered with age.
Mice exposed during gestation and lactation to methylmer-
cury who were normal at birth developed deficits in
exploratory behavior and swimming ability at 1 month, and
neuromuscular and immune effects as the animals reached
1 year of age. Monkeys exposed developmentally to
methylmercury developed motor incoordination when they
reached middle age. Monkeys exposed in titero and
postnatally exhibited hearing deficits in middle age, which
grew relatively worse during old age compared to controls,
providing evidence for an interaction of aging and meth-
ylmercury exposure on auditory impairment. All of these
observations are consistent with a hypothesis that early
life or in utero exposure to methylmercury can have
adverse long-term sequelae that may not be detected in
childhood. It further suggests that exposure in adulthood
that results in signs of mercury toxicity can result in an
exacerbation of the effects of aging. Both mechanistic and
descriptive studies are needed to understand the basis of
these effects, and at what body burden they occur.
Identification of impacts from aggregate exposures and
synergistic effects of methylmercury and other pollutants.
A need exists to identify the risk assessment uncertainties
following aggregate exposure to developmental neurotox-
ins. An improved mechanistic understanding of the
developmental neurotoxicity of methylmercury is needed to
assist in understanding the additive, subtractive, and
synergistic relationships among other commonly occurring
environmental pollutants (e.g., dioxin, PCBs,
dibenzofurans). Human epidemiological data are often
complicated by exposure to a combination of many
pollutants (e.g., Great Lakes fish and marine mammals; fish
of the North Sea), and more research is needed to charac-
terize the neurotoxicity and immunotoxicity of aggregate
exposures.
Improved understanding of the modulation of immune
system response from methylmercury exposure. A need
exists to improve the Agency's understanding of the
toxicity of mercury and methylmercury to additional organ
systems. Recent data suggest that exposure to mercury
compounds through a number of routes can modulate
immune responses. Immunomodulation is manifested as an
adverse effect in three general areas: autoimmunity,
immune suppression (with enhanced risk for infectious
disease), and allergy. Specific research findings in these
areas include:
• Autoimmunity. Mercury exposure in either experimental
animal models or in humans has been shown to be a
potent stimulus for the expression of autoantibodies
and autoimmune responses in some susceptible
populations. The risk for latent autoimmune diseases
following low-level developmental exposure of children
is largely unknown.
• Immune Suppression. Methylmercury has been
reported to be a potent effector of immune suppression,
including both humoral responses and natural killer cell
activity. Humoral response consists of antibody
production; natural killer cell activity protects against
infectious agents. The subsequent effects of
developmental exposure, at least in experimental
animals, indicate that there is an increased risk,
principally during the postnatal period, leading to
increases in the number and severity of infections later
in life.
• Allergy. Exposure to either organic or elemental
mercury is a well-known environmental stimulus of
allergic responses (i.e., contact dermatitis) in humans
and animals. These responses have been demonstrated
in adults and children. There is, however, little clear
evidence to date of age-related sensitivity either
qualitatively or quantitatively.
These findings raise the following questions which need to
be addressed: How does developmental exposure to
methylmercury affect immune responses and susceptibility
to disease? What components of the immune system are
affected? Is there a critical window of opportunity? What
are the dose-response relationships? What are the
underlying mechanisms? How do answers to these
questions compare to developmental neurotoxicity, another
critical effect?
Susceptibility to immunotoxic effects may differ substan-
tially across exposed populations. Factors that predispose
the organism to autoimmunity and/or allergic responses are
not well characterized in humans. WHO (1991) concluded,
based on animal studies, that the most sensitive adverse
effect for inorganic mercury risk assessments is the
formation of mercury-induced autoimmune glomerulone-
phritis. Understanding dose-response among sub-
populations that are particularly sensitive to the
immunotoxic effects of mercury is limited and it is not
scientifically possible to set a level of exposure below
which mercury-related symptoms will not occur. This
observation raises research questions, including the
following: What is the magnitude of the risk of autoim-
mune disease associated with exposure to inorganic
mercury? What is the dose-response relationships? Are
there sensitive populations, and is the developing immune
system particularly vulnerable? How can experimental
animal research and epidemiology studies be linked to
improve the risk assessment process?
Improved understanding of the effects on cardiovascular
function as a result of methylmercury exposure. There are
some human data linking cardiovascular effects with
exposure to elemental, inorganic, and organic forms of
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mercury. In addition, there are two recently published
studies that show an association between low-level
methylmercury exposure and cardiovascular effects. In a
study of Faroese children, diastolic and systolic blood
pressures increased as the cord-blood mercury increased
from 1 to 10 ug/L. I a study in Finland, men with hair
mercury 2 ppm or higher, had a 2.0 times greater risk of
acute myocardial infarction than the rest of the study
population. Relatively subtle effects of methylmercury on
cardiovascular indices may have public health implications.
As demonstrated with lead exposure, even a small eleva-
tion in blood pressure results in an increase in both
myocardial infarctions and deaths.
Biological monitoring for model development and
improvement. There is a need to conduct biological
monitoring of sensitive populations who consume large
amounts offish and seafood in order to determine methyl-
mercury intakes from diet and monitor blood- and hair-
mercury concentrations. These sub-populations should
include young children as well as adults and ethnically
diverse groups. The populations should include groups
who ingest fish and marine mammals that are highly
contaminated with methylmercury (e.g., people consuming
fish from contaminated freshwater lakes) and those who
consume high levels offish and marine mammals with
typical (e.g., 0.05 - 0.2 ppm) mercury concentrations. The
biomonitoring data need to be collected in a way that
permits the development of toxicokinetic models that
describe the tissue distributions of the comparable doses
of mercury and methylmercury that are ingested in diverse
temporal patterns.
Development of toxicokinetic data on methylmercury
tissue distribution. Research is needed to establish the
kinetic patterns (e.g., tissue distribution, ratios of hair
mercury to blood mercury to dietary intakes) of mercury
distribution following ingestionby children of methylmer-
cury from dietary sources. Such data form the basis of a
toxicokinetic model for predicting changes in risk from
changes in the amount of exposures to mercury and
methylmercury.
5.9.1.4 Research Results
Results from this research will be factored into refined
mercury human health risk assessments that will be used to
support future policy decisions on safe mercury levels for
susceptible populations. Using these refined risk assess-
ments, the Office of Air and Radiation (OAR) and the
Office of Water (OW) will be able to make improved
regulatory decisions on mercury atmospheric emissions
and provide more informed guidance on methylmercury in
water bodies. This work will also assist States and Regions
in deciding when fish consumption advisories are needed
to protect public health from methylmercury.
5.9.1.5 Measures of Success
Researchers hope to advance the following:
• A sufficient understanding of the biokinetics of mercury
and methylmercury in young children to permit interpre-
tation of monitoring and modeling data from various
ongoing research projects.
• An improved determination as to whether young
children or maternal-fetal pairs are the population at
greatest risk from methylmercury exposures.
• An improved determination concerning the relative
sensitivity of neurotoxic, immunotoxic, and cardiovascu-
lar effects.
• Improved understanding of the mechanism of delayed
neurotoxicity, and the body burden at which it occurs
• Measurable improvement in the scientific understanding
of the variability in fish/methylmercury consumption
among the most highly exposed sub-populations in the
United States.
• Measurable improvement in the scientific understanding
of the relationship between risk from fish and marine
mammal consumption during childhood, and risk from
fish and marine mammal consumption during fetal
development.
5.9.1.6 Preliminary Performance Goals
GPRA performance goals have been identified for the
human health effects and exposure research area based on
the above Measures of Success; they are preliminary in
nature and will be revised and adjusted as part of the
implementation of the Mercury Research Strategy. ORD
anticipates that completion of the MRSvi\\\ take approxi-
mately five to ten years depending on funding levels and
any adjustments for changing Program Office and Regional
needs. A preliminary set of performance goals is offered
below. The performance goals are:
• By 2005, identify the impacts from aggregate exposures
and synergistic relationships among other commonly
occurring environmental pollutants (e.g., dioxin, PCBs,
dibenzofurans).
• By 2007, establish the relationships between low-dose
exposure to methylmercury throughout the life span of
humans and animals and carcinogenic, reproductive,
neurological, and immunological effects.
• By 2009, establish the relationships among delayed
neurological effects after years of methylmercury
exposure, especially any effects as a result of low-dose
prenatal exposures.
• By 2009, provide toxicokinetic models that describe the
underlying toxicity of methylmercury to a variety of
susceptible populations.
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5.10 RKKCOMMUNICATION
5.10.1 Key Scientific Question
What are the most effective means for informing
susceptible populations of the health risks posed
by mercury and methylmercury contamination of
fish and seafood?
5.10.1.1 Background
EPA anticipates a long lag time in controlling environmen-
tal levels of methylmercury, a known neurotoxin. If all
current anthropogenic emissions of mercury ceased
immediately, humans would still be exposed to elevated
methylmercury levels in fish and seafood for a number of
years. This lag from control of anthropogenic sources to
measurable reductions in environmental mercury contami-
nant levels is the result of global mercury cycling from
natural and re-emitted sources. Regardless of the time it
takes to see meaningful reductions of mercury in both fish
and humans as emissions are reduced, EPA must clearly
communicate the facts on mercury and methylmercury to
those exposed. In particular, the Agency needs to effec-
tively communicate the nature and extent of risks to human
health posed by methylmercury fish and seafood contami-
nation to members of susceptible populations.
Susceptible populations include people consuming above-
average amounts offish (e.g., more than approximately 10
grams per day) on a regular basis. Higher than average
consumption of fish and other seafood is found among
people of Asian and Native American ethnicity, recre-
ational anglers and their families. People who are subsis-
tence fishers may be a particularly important population
with respect to methylmercury exposures. The extent of
exposure depends on the amount of fish consumed and on
the methylmercury concentrations in the fish. Methylmer-
cury adversely affects the developing nervous system at
lower exposure than it affects adult neurological function-
ing. Consequently, women of childbearing age, maternal/
fetal pairs, nursing mother/infant pairs, and young children
are all included as susceptible populations. Because brain
development continues during early childhood, young
children, along with pregnant/nursing mothers, need to be
aware of the health hazards posed by ingestion of an
excessive amount of methylmercury from fish and seafood.
5.10.1.2 Program Relevance
The Agency works with various communities and exposed
populations to inform them of the dangers they face from
environmental contaminants. This philosophy of commu-
nity involvement forms the basis for fish advisory pro-
grams supported by EPA and run by state and local
organizations and governments. As noted earlier, EPA
anticipates a long lag time in reducing environmental levels
of methylmercury once anthropogenic mercury sources are
controlled. Better-informed populations and individuals
need information delivered in a way that helps them
understand the magnitude of methylmercury exposures
produced by particular patterns of fish consumption. An
adequate research base is needed to effectively inform
populations at risk of their potential exposures. Exposure
data and the effectiveness of its delivery provides useful
dose-response information to assist in making informed
choices on fish and seafood consumption. There are
several research needs related to risk communication. The
amount of mercury and methylmercury in fish varies
markedly with geographic location, which reflects the
impact of local factors. For example, similar lakes within a
few miles of each other may have decidedly different
methylmercury bioaccumulation patterns in fish. Conse-
quently there is a need for monitoring data on mercury and
methylmercury levels in water bodies and in fish. These
data provide specific information to individuals and
groups consuming fish from these water bodies.
5.10.1.3 Prioritized Research Needs
• Synchronization offish consumption advisory mes-
sages for methylmercury.
• Improved understanding of exposure patterns in
targeting of risk messages.
• Increased use of risk information in making decisions
about methylmercury exposures.
Synchronization offish consumption advisory messages
for methylmercury. Research on how individual states
have arrived at their fish advisory decisions is needed.
Current state advisories on fish consumption use a variety
of health-based approaches in setting advisory levels.
Although all of these values are based on methylmercury
concentrations in fish, some use EPA's RfD, some use
ATSDR's 1999 revision of the Minimal Risk Level (MRL),
and some use FDA's Action Level. In view of the National
Academy of Science support for EPA's RfD as the appro-
priate level for protection of public health, the development
of a synchronized strategy to communicate risk is preferred
to the current approach.
Improved understanding of exposure patterns in target-
ing of risk messages. Data on the distribution patterns of
fish consumption is needed. The Agency is concerned
about risks resulting from exposure to methylmercury from
multiple sources. For example, certain populations may
consume both locally caught and commercial fish. Both of
these sources offish may be contaminated with methylmer-
cury resulting in additive exposures. In the past, risk
communications from the Agency have focused almost
exclusively on locally caught fish. By contrast, several
states include commercial fish in their advisories. A
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challenge for the Agency is to develop approaches to
communicate risk from methylmercury in both commercially
available and locally caught fish.
In developing risk communication materials, an analysis of
data on how much mercury populations are exposed to
from fish is needed to provide a better basis for alerting
individuals and groups about their level of risk from
methylmercury exposures. A recommendation for obtain-
ing data on human exposure to methylmercury from fish is
also made under the human health effects and exposure
key scientific question. Specifically, data are needed to
describe the distribution of mercury concentrations in
locally caught and commercially available fish are required
in order to accurately inform susceptible populations of
their total exposure to methylmercury. Data needs include
the distribution of patterns of fish consumption.
Increased use of risk information in making decisions
about methylmercury exposures. An additional risk
communication research need is understanding how people
use risk information to make informed decisions regarding
methylmercury exposures. This is particularly complex
because the populations at greatest risk (e.g., infants,
young children) have not reached a level of cognitive
development to permit such choices. The individuals or
groups to reach are parents or other responsible people.
This area of risk communication has rarely been explored
and represents a major opportunity for EPA to play an
effective role in its development. Populations at highest
risk of methylmercury exposure from eating fish include
some immigrant groups (e.g., persons of Asian and Pacific
Island ethnicity), specific Native American tribes, individu-
als who may be pursuing a "healthy diet" (e.g. a diet high
in polyunsaturated fatty acids to reduce the risk of
cardiovascular disease), as well as individuals who simply
prefer not to consume red meat. Because the motivations
of these various individuals and groups differ markedly,
research on how to communicate risk is likely to vary
greatly also. Research is needed on how to successfully
communicate the risk of methylmercury to such divergent
populations, groups and individuals. Such messages are
complex for two additional reasons: (a) the health benefits
offish consumption, and (b) differences in mercury
concentrations in fish depending on species, size, and
geographic location.
5.10.1.4 Research Results
Results from this research will contribute to a risk commu-
nication program for methylmercury in several ways. There
is a need to synchronize fish consumption advisory
messages for the numerous states in which they are issued.
An understanding of how states have chosen to make fish
advisory decisions would be an essential element of any
synchronization effort. An improved understanding of
exposure patterns (e.g., amount of fish consumed, types of
fish consumed, frequency of consumption) will assist in
targeting populations and the messages those populations
receive regarding methylmercury exposure based on fish
consumption. This work will assist Program Offices and
Regions, state and local governments, and other public and
private groups in providing more effective risk information
on methylmercury exposures.
5.10.1.5 Measures of Success
Researchers hope to advance the following:
• Mapped distribution of mercury levels in fish found in
all waterways of the United States.
• Identification of the risk communication styles utilized
by women of childbearing age from ethnically-diverse
populations.
• Identification of the populations (based on ethnic,
racial, economic, tribal groups) of greatest concern with
regard to ingestion of methylmercury from fish and
seafood.
• Development of fish advisories of proven effectiveness
that reach 90 percent of the at-risk population.
• Development of a consistent state advisory system
based on the use of EPA's RfD which was judged by the
National Academy of Sciences Committee to be the
scientifically justifiable value for protection of public
health.
• Development, with appropriate professional groups
(e.g., obstetricians, state medical officers, state fishery
experts), of risk messages aimed at informing particular
sub-populations.
• Focus group testing of risk messages to multi-cultural,
multi-ethnic groups of women of child-bearing age to
determine how to promote changes in fish consumption
behavior.
• Utilization of multimedia sources of risk information
(e.g., web-based and other electronic media).
5.10.1.6 Preliminary Performance Goals
GPRA performance goals have been identified for the risk
communication research area based on the above Mea-
sures of Success; they are preliminary in nature and will be
revised and adjusted as part of the implementation of the
Mercury Research Strategy. ORD anticipates that comple-
tion of the MJfS"wi\\ take approximately five to ten years
depending on funding levels and any adjustments for
changing Program Office and Regional needs. A prelimi-
nary set of performance goals is offered below for the risk
communication research area. The performance goals are:
• By 2005, describe risk communication styles for those
populations with the greatest exposure to methylmer-
cury in fish and seafood.
• By 2007, determine the best methods of communicating
risk from methylmercury in fish and risk management
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opportunities for mercury reduction, both domestically
and internationally.
1. International data on mercury use and releases are difficult
to obtain. For non-combustion sources, a few countries (e.g.,
Sweden) appear to be more advanced in reducing mercury
use. Mercury use appears to be growing in many other
countries, especially developing nations, where their releases
are often poorly controlled. International sources may have
more significant releases to the global mercury pool than
those from the United States. The Agency is developing an
international mercury strategy into which the results of
research described in this section will feed. (Unless otherwise
stated, all discussions in this section deal with the use and
release of mercury in the United States.)
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6.0 ISSUES BEYOND THE MERCURY
RESEARCH STRATEGY
The Mercury Research Strategy describes ORD's research
program to reduce the scientific uncertainties related to
mercury and methylmercury risks. There are, however,
additional issues that the Afl?S"Wntmg Team believes are
important but which lie outside the scope of the mercury
research program. These include science activities not
considered "research," but that inform research efforts.
Another issue is the development and implementation of
mechanisms that encourage future research partnering
external to EPA.
6.1
SCIENCE ACTIVITIES THAT GO
BEYOND RESEARCH
In the process of preparing the MRS, ORD identified three
science activities that provide data and information
important to the success of the Agency's mercury risk
assessment and risk management efforts. These three
activities are: (1) improving mercury emission inventories
and collecting source emission data, (2) monitoring
mercury in various media, and (3) understanding the
international implications of mercury. Each is described
below in greater detail, as is ORD's suggested approach for
addressing them. Furthermore, the information developed
from these three activities will help EPA attain the goals
identified in the Agency's Mercury Action Plan and in
other documents including: A Multimedia Strategy for
Priority Persistent, Bioaccumulative and Toxic (PUT)
Pollutants-, Deposition of Air Pollutants to the Great
Waters: Third Report to Congress; and North American
Regional Action Plan for Mercury - Phase ^(Federal
Register, 1998; EPA, 2000a; CEC, 2000). Resulting data and
insights will allow for periodic adjustments in implementa-
tion of the Mercury Research Strategy.
6.1.1 Improving Mercury Emissions
Inventories and Collecting Source
Emissions Data
EPA collects data on mercury sources and releases from
the National Toxics Inventory (NTI); it is the most compre-
hensive mercury emissions inventory of U.S. anthropo-
genic sources available. Nevertheless, EPA's current
understanding of mercury sources and their characteriza-
tion needs enhancement. The NTI provides a compilation
of emissions estimates for all listed hazardous air pollutants
(HAPs) for point, area, and mobile sources. It incorporates
information from the Toxics Release Inventory (TRI), which
includes manufacturers' submitted estimates of facility
emissions to EPA, state and local inventory data, and data
from other special studies. With respect to available
information, EPA's TRI does not include mercury estimates
for U.S. anthropogenic sources; that will change for the
1999 reporting period (due in 2001). In the 1999 reporting
year, mercury releases of 10 pounds or more must be
reported (Federal Register, 2000). The 1999 TRI inventory
will not contain information on mercury species. EPAis
gathering mercury emission data, for coal-fired utilities as
part of the Utilities Information Collection Request (ICR).
The ICR does contain some speciated mercury data.
EPA needs to better quantify, characterize, and inventory
mercury released from domestic, non-combustion anthro-
pogenic sources, diffuse area sources, and natural sources.
There is also a need for data showing trends in mercury
releases from these sources, both domestically and
internationally. These trends will demonstrate the effec-
tiveness of mercury source reduction efforts. An inven-
tory of national and international speciated mercury is
essential to effectively model mercury releases from human
activities and predict deposition and concentrations in the
environment. ORD is exploring how best to address these
needs with the Program Offices (particularly OAR, OW,
OPPTS, and OIA). ORD has adjusted the MRS to focus
more effort on anthropogenic releases of mercury from
non-combustion sources. This will be done as part of the
risk management for non-combustion sources research
area.
6.1.2 Monitoring Mercury in Various Media
While no comprehensive, national monitoring network for
mercury has been developed, an increasing number of
mercury monitoring activities are underway. EPA and
others have developed ambient air and deposition monitor-
ing networks that address mercury (with other pollutants)
on local or regional scales (EPA, 2000a; CEC, 2000). There
is, however, a need for statistically-representative monitor-
ing data that provide a baseline against which progress in
mercury risk management can be measured. ORD recog-
nizes the need to develop and implement such a network,
including the tracking of indicators to demonstrate
changes in mercury concentrations in the environment. In
particular, data are needed on both fish tissue (the primary
route of human and wildlife exposure) and susceptible
populations. This biomonitoring would track mercury
concentration trends in both humans and fish.
EPAis preparing an Action Plan for mercury, one of the
twelve priority pollutants identified in the Draft Persistent
Bioaccumulative Toxics (PBT) Strategy (Federal Register,
1998). This action plan recommends the development of a
comprehensive and focused National Mercury Monitor-
ing Strategy (which may be expanded to include other
PBTs). The monitoring strategy is intended to harmonize
48
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monitoring programs underway by federal and state
agencies and to achieve efficient and comprehensive
mercury analyses on a national scale. It will include
atmospheric, water, soil/sediment, and tissue monitoring.
A weighted sampling design is envisioned for long-term
monitoring on a broad scale. More intense monitoring,
including key interacting variables, will be proposed for a
set of sentinel sites. While ORD will participate in the
design and implementation of this National Mercury
Monitoring Strategy and consult in the network's opera-
tion, it does not intend to operate the network. The
operation of a monitoring network of this magnitude lies
outside of ORD's mission, and must be a coordinated effort
among the Program and Regional Offices, states, and other
organizations.
6.1.3 Understanding the International
Implications of Mercury
It is increasingly clear that the atmospheric, transboundary
nature of mercury needs to be considered as part of any
mercury risk management effort in the United States.
Based on the Mercury Study Report to Congress (EPA,
1997a), the estimated emissions of mercury from the U. S.
are relatively small when compared to releases worldwide.
Mercury, like other hazardous air pollutants, is both a
global and national issue. A better understanding of how
mercury cycles through the global environment is essential
to achieve the effective management of mercury risks. The
most pressing questions that remain regarding mercury
revolve around mercury transport, transformation, and fate
from emission release point through bioaccumulation in
fish. In addition, a better understanding is needed of
mercury chemistry, thermodynamics, and kinetics, both in
the atmosphere and aquatic ecosystems.
On the global front, EPA's Office of International Activities
and Office of Air and Radiation are contemplating the
development of an International Mercury Strategy. The
strategy will set the framework and rationale to guide the
Agency's efforts, in concert with other organizations and
the international community. The international strategy will
focus on collecting scientific data, building international
partnerships, and influencing risk management decisions,
all with the goal of preventing or reducing mercury risks
worldwide. ORD plans to contribute to the development
and implementation of this strategy.
6.2 FOSTERING FUTURE RESEARCH
PARTNERSHIPS
Engaging and partnering with a variety of stakeholders will
enhance ORD's mercury research program. ORD wants to
strengthen research links to the regulated community, in
order to gain their participation and sponsorship of
mutually beneficial mercury research. It is seeking links to
states, communities, and tribes, in order to gather insights
from decision makers at various community levels on their
mercury research needs. The MJfS"Wntmg Team has
worked closely with EPA's Program Offices and Regions to
understand their research needs and involve them in the
development of the Mercury Research Strategy.
ORD is now engaging other organizations in order to
exchange information on mercury research and develop-
ment activities and to advance its mercury research
program. One area deserving attention involves Native
Americans, particularly those individuals and tribes who
rely on fish for a significant part of their diets. ORD will
work through the newly-formed Tribal Science Council and
as appropriate, the Arctic Monitoring and Assessment
Program, to engage Native Americans on mercury issues.
In both cases, these engagements will inform ORD's
mercury research program, and in particular, the risk
communication research area. Involvement with the
international community will be pursued under the aus-
pices of the International Mercury Strategy as it evolves
in the coming months and years.
Examples of existing partnerships and potential opportuni-
ties for partnering with federal, private, public, and
academic organizations are described in Chapter 4.0. For
example, ORD has partnered with the U. S. Geological
Survey (USGS) in establishing a USGS/EPA Mercury
Roundtable. The Roundtable sponsors regularly sched-
uled meetings for the staffs of the two organizations to
discuss science and its role in affecting policy related to
mercury. Both organizations anticipate that this forum will
evolve into a more broadly-based Federal Mercury
Roundtable in the coming months. One outcome of this
federal agency engagement is envisioned to be a biennial
conference on federal agency mercury and methylmercury
research. This conference will bring together not only EPA
and USGS researchers, but others in the public and private
sectors conducting pertinent research on mercury.
49
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APPENDKA
SUMMARY OF STAR GRANTS PROGRAM AWARDS
Mercury: Transport and Fate through a Watershed
Appendix A contains a summary of grants awarded as part of ORD's Science to Achieve Results
(STAR) Grants Program on mercury transport and fate through a watershed. In 1998, ORD issued a
Request for Applications (RFA) inviting interested parties to submit research ideas that advance
the fundamental understanding of chemical and physical transformations and movement of
mercury in the environment (EPA 1998e). The awards summarized below were made in September
1999 and generally have a lifetime of three years. Specifically, the grants focus on the aquatic and
terrestrial transport, transformation, and fate of mercury. The total funding for the research
program over its three-year life is approximately $6.2 M. Each summary includes a description of
the research being conducted, the institution conducting the research, and the principal
investigator(s) leading the efforts. The summaries were prepared by the Principal Investigators as
part of their proposal submissions. Additional information on the STAR Grants Program can be
obtained by contacting EPA's National Center for Environmental Research (NCER) at http://
www.es.epa.gov/ncerqa/.
Title: Methylmercury Sources to Lakes and Forested Watersheds: Has Enhanced Methylation
Increased Mercury in Fish Relative to Atmosphere Deposition?
Institution: University of Minnesota/Minnesota Pollution Control Agency
Principal Investigator: Edward B. Swain
Summary;
The study will investigate enhanced methylmercury loads that results in elevated mercury concen-
trations in fish. The objectives of the study are to: (1) establish the relative importance of atmo-
spheric, in-lake, and wetland sources of methylmercury to a lake in a forested watershed containing
three types of wetlands; (2) determine the net retention and source strength of different wetland
types; (3) conduct mesocosm (wetland and lake) and whole wetland experiments to elucidate
methylation enhancing processes; and (4) add a hydrologically-based wetland GIS module to the
Mercury Cycling Model (MCM) to apply finding to a larger set of lakes where GIS and mercury
data have been collected.
The research will be conducted by the University of Minnesota and the Minnesota Pollution
Control Agency and will focus on the sediments and fish in lakes within the State of Minnesota.
Researchers hope to apply the study's findings to other regions of the country. The study will use
a three-tiered approach involving microspace experiments, lake/wetland studies, and evaluation of
the new understanding through modeling. Through this study, researchers will improve the
understanding of the sources of methylmercury in fish and explain the observed differences in fish
mercury levels in Minnesota and elsewhere.
Title: Response to Methylmercury Production and Accumulation to Changes in Hg Loading: A
Whole-ecosystem Mercury Loading Study
Institution: The Academy of Natural Sciences Estuaries Research Center, The University of
Maryland, Chesapeake Biological Laboratory, Canada Department of Fisheries and Oceans,
Freshwater Institute.
Principal Investigator: Cynthia C.Gilmore
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Summary:
The study attempts to understand the mercury cycle by studying methylmercury production as
part of a whole-ecosystem mercury loading experiment. Researchers will attempt to answer the
question of "How much does methylmercury in an ecosystem change in response to a change in
mercury loading?" The study will measure the net accumulation of methylmercury, instantaneous
methylmercury production and degradation rates, and the key biogeochemical parameters in each
of these locations that affect mercury bioavailability and methylation.
The research will be conducted by several institutions (see above). United States and Canadian
scientists will conduct the research at the Experimental Lakes Area (ELA) in northwestern Ontario.
In addition, an experiment will also be conducted in the Florida Everglades for comparison of
mercury loading. Researchers will use two approaches to study mercury loadings: (1) the stable
mercury isotopes and (2) the manipulation of a whole watershed with mercury. The results will
allow researchers to predict changes in methylmercury from changes in mercury loading over the
range of mercury loadings that would result from regulatory action. The resulting data will also
provide insights on regional and landscape variations that affect methylmercury production and
accumulation in fish.
Title: Photo Induced Reduction of Mercury in Lakes, Wetlands, and Soils
Institution: University of Michigan, Oak Ridge National Laboratory
Principal Investigator: Jerome O. Nriagu
Summary:
The study will evaluate photosynthesis induced formation of mercury in a watershed. A compari-
son between the similarities and differences in pathways and rates of mercury formation in different
segments of a watershed will be conducted. The study will measure the diurnal and seasonal
variations in cross-gradient generation of mercury and total release of mercury from surface waters.
The experiments will be conducted in both laboratory and field conditions. The field study will take
place at Saginaw Bay and Lake Huron. Researchers hope that the data will help explain the process
of natural mercury release into the environment and the role of this process in reducing the amount
of mercury loading in the Great Lakes.
Title: Chemical and Biological Control of Mercury Cycling in Upland, Wetland and Lake
Ecosystems in the Northeastern U.S.
Institutions: Syracuse University, Cornell University, Smith College, Tetra Tech, Inc.
Principal Investigator: Charles T. Driscoll
Summary:
The study will attempt to clarify the chemical and biological processes that regulate mercury
transport, fate, and bioavailability in the northeastern United States. The study will also attempt to
develop and apply a simulation model to explain these processes. The research objectives are to:
(1) quantify patterns of transport and transformations of mercury species in an upland northern
hardwood forest through adjacent wetlands; (2) evaluate the processes and mechanisms control-
ling methylmercury concentrations and transport in pore-water and surface water in wetlands; (3)
evaluate historical patterns of mercury dynamics in soft-water lakes; and (4) develop and apply a
lake/watershed mercury cycling model to a lake/watershed ecosystem.
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The project will examine the: (1) transport of mercury and interactions with organic matter and
metals in upland soil, wetlands and surface waters; (2) rates and controls of methylation and
demethylation of mercury in organic matter-rich wetland environments; and (3) factors which
influence historical changes in the deposition of mercury to lake sediments. Field watershed
measurements and controlled experiments will be employed to quantify mercury behavior in a
typical glaciated landscape in the Adirondack Region of New York.
The result of this study will provide information to the EPA and agencies in the northeast con-
cerned with the consequences of elevated atmospheric mercury deposition. The study will
develop and calibrate a comprehensive watershed mercury cycling model to be used in assessing
regional effects of atmospheric mercury deposition on watershed and lake ecosystems.
Title: Processes Controlling the Chemical/Isotopic Speciation and Distribution of Mercury from
Contaminated Mine Sites
Institution: Stanford University, University of Nevada-Reno, U.S. Geological Survey
Principal Investigator: Gordon E. Brown, Jr.
Summary:
Researchers will attempt to understand the physical and chemical processes that control the
speciation and distribution of mercury in mine wastes and its release from mine sites. The study
will attempt to (1) determine the chemical and isotopic speciation of mercury in natural samples; (2)
test the transport of mercury on colloidal particles in laboratory column experiments; (3) examine
the sorption processes of mercury on mineral particles common in sediments downstream from
mine sites, as well as the effects of common aqueous ligand sulfate and chloride on Hg sorption
processes; and (4) monitor the atmospheric emissions of mercury from selected mine waste sites
representing different weathering and climatic regimes. The objective is to correlate emission levels
with the chemical speciation of mercury in the mine wastes. Researchers will conduct the experi-
ments at selected mining waste sites in the western United States.
The chemical and isotopic forms of mercury associated with mining wastes will be determined
using spectroscopic and isotopic methods. Laboratory column experiments will be conducted to
examine the transport of mercury by colloids. Sorption experiments will be conducted to examine
the sorption of mercury on mineral particles. To measure atmospheric emissions of mercury,
micrometeorological and flux chamber methods will be used. The result of the study will allow
researchers to better understand the process involved in speciation and distribution of mercury in
mining waste. It will also allow scientists to better characterize the risk associated with mercury in
mine wastes for local and regional ecosystems.
Title: Microbiological and Physicochemical Aspects of Mercury Cycling in the Coastal/
Estuaries Waters of Long Island Sound and Its River-Seawater Mixing Zones.
Institution: Department of Marine Sciences, University of Connecticut
Principal Investigator: William F. Fitzgerald
Summary:
This research is designed to better understand how mercury cycling in natural water plays a key
role in controlling the overall aquatic biogeochemistry of mercury and the bioavailability of mercury
species. The study is a three-year comprehensive examination of the physicochemical and
microbiological marine program to investigate reactions and processes controlling mercury
emissions, cycling, and bioavailability in Long Island Sound and its watershed/coastal water
interface. The objective of the study is to understand the aquatic biogeochemistry of mercury and
interactions between the terrestrial watersheds and near shore marine waters.
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The program will take place at the estuaries and coastal waters in Long Island Sound. Scientists
will use previous mercury mass balance studies and are proposing an experimental and theoretical
design that will allow the results to be applicable to other regions. The experimental aspect of the
study will be conducted largely in the field but also will involve laboratory experiments. The
project increases the understanding of the role and environmental impact of in-situ mercury
production and emissions on the aquatic and atmospheric mercury cycle. Researchers also hope to
evaluate the importance of the in-situ biological synthesis of methylmercury on the behavior and
fate of this toxic species in Long Island Sound and other areas.
Title: Understanding the Role of Sulfur in the Production and Fate of
Methylmercury in Watersheds
Institution: Chesapeake Biological Laboratory, University of Maryland, Academy of Natural
Sciences Estuaries Research Center
Principal Investigator: Dr. Robert P. Mason and Dr. Cynthia Gilmore
Summary:
Researchers will investigate the influence of sulfide and other parameters, and the relative impor-
tance of microbial community structure and activity to net methylmercury production in natural
sediments and soils. The objective of this project is to understand the role of sulfur in mercury
methylation and methylmercury fate and transport in watersheds. The hypothesis is that the
decreased methylation of mercury in high sulfide environments results from changes in mercury
availability to the methylating organisms while low production in sulfate-limited systems is driven
by limitation of microbial activity.
Laboratory and field experiments will be conducted. Bioavailability of mercury to methylating
organisms will be determined using bacterial cultures and natural sediments and soils, combining
laboratory, field and mesocosm experiments. Engineered microorganisms will also be used to test
the hypothesis about factors controlling mercury uptake by methylating bacteria. The study
results will provide information needed to understand the factors controlling the formation,
degradation, fate and transport of methylmercury in watersheds. In addition, the results will
provide new information regarding the relationship between atmospheric deposition of mercury to
watersheds and mercury bioaccumulation in piscivorous fish.
Title: The Redox Cycle of Mercury In Natural Waters
Institution: Department of Geosciences, Princeton University
Principal Investigator: Francois M. M. Morel
Summary:
The study will provide a better understanding of the parameters that control the flux of elemental
mercury from natural waters to the atmosphere. Researchers will conduct a series of iterative
laboratory and field experiments focused on the principal chemical and biological redox mecha-
nisms that transform mercury between its divalent and elemental forms. Researchers will model
simple systems and build up to more complex models of natural waters. Lab experiments will create
the mechanisms and the rates of the processes of interest and will provide methods and probes for
the field experiments.
The field experiments will cover a number of sites and will attempt to establish the actual occur-
rences of the mechanisms in nature and provide kinetic data. The result of the project will allow for
better understanding of how parameters affect the rate of mercury loss from bodies of water to the
atmosphere. It will also help answer the question of why bodies of water with similar inputs of
mercury end up having different mercury loadings.
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Title: Watershed Influences on Transport, Fate and
Bioavailability of Mercury in Lake Superior
Institution: Bureau of Integrated Science Services, Wisconsin Department of Natural Resources,
University of Wisconsin-Madison, and Lake Superior State University
Principal Investigator: James P. Hurley
Summary:
This study will assess the importance of watersheds in controlling sources, transport, fate and
bioavailability of mercury in a northern temperate lake system. The specific objectives of the study
are to: (1) determine the speciation and bioavailability of mercury transported to Lake Superior by
representative tributaries/watersheds; (2) determine the importance of watershed-specific charac-
teristics (soil type, land use, surficial deposits) that control physical/chemical forms of mercury
transported downstream; (3) identify key mechanisms controlling mercury bioavailability and
speciation in near-shore zones relative to open lake regions; and, (4) provide process-level
information to complement concurrent development of mercury fate and transport models of the
Lake Superior ecosystem. The approach uses a combination of field and laboratory studies with
modeling to assess the importance of watershed processes in controlling mercury fate and trans-
port in Lake Superior. Anticipated results will provide information on the links between atmo-
spheric mercury deposition and accumulation of mercury in biota within the Lake Superior Basin.
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