United States
          Environmental Protection
Office of Water
EPA 823-R-95-002
June 1995
&EPA    National  Forum on
          Mercury  in Fish



National Forum on
Mercury in Fish

 National Forum on
   Mercury in Fish
       September 27-19, 1994
       New Orleans, Louisiana
       Printed on Recycled Paper


                                  WASHINGTON, D.C. 20460
                                                                               OFFICE OF
  Dear Colleagues and Interested Parties:
              EPA  OW Resource Center (RC4100)
              401 M St. SW                   /
              Washington, DC 20460

              Phone Recording Order:  (202) 260-7786
              FAX Order:   (202) 260-0386
              Email:        waterpubs@epamail.epa.gov
   We appreciate the contributions of the speakers
workshop and we look forward to your continued
  and others who participated in the
interest in fish contamination issues.
                                 Rick Hoffmann
                                 Forum Organizer
                                 Risk Assessment and Management Branch
                                 Office of Science and Technology
                (A. A)

                 National Forum on
Mercury in Fish
Abstract	                      ^
Acknowledgments	    jx


     Welcome and Introduction	1
     Mr. James Hanlon and Mr. Rick Hoffmann

  Session One: Mercury Overview and Background

     Biogeochemical Cycling of Mercury: Global and Local Aspects	3
    Dr. William Fitzgerald

    Aquatic Biogeochemistry and Mercury Cycling Model (MCM)	15
    Dr. Donald Porcella

    Mercury Methylation in Fresh Waters	   23
    Dr. Cindy Gilmour

    Considerations in the Analysis of Water and Fish for Mercury	31
    Mr. Nicolas Bloom

    Bioaccumulation of Mercury in Fish	41
    Dr. James Wiener

    Mercury in Wildlife	   53
    Dr. Charles Facemire

    Questions and Discussion: Mercury Overview and Background	63

 Session Two: Florida Studies

    Ecological Assessment of Mercury:  Contamination in the Everglades
    Ecosystem	....71
    Dr. Jerry Stober

    Atmospheric Deposition Studies in Florida	„	77
    Dr. Thomas Atkeson

    Watershed Effects on Background Mercury Levels in Rivers	83
    Dr. James Hurley

    Questions and Discussion: Florida Studies	89

                                           National Forum on Mercuiy in Fish

  Session One: Toxidty and Risk Assessment

     Mercury Toxicity: An Overview [[[ 91
     Dr. Thomas Clarkson

     Neurobehavioral Effects of Developmental Methylmercury Exposure in
     Animal Models [[[ 95
     Dr. Deborah Rice

     An Overview of Human Studies on CNS Effects of Methylmercury ............. 109
     Dr. RobertaWhite

     Exposure Assessment for Methylmercury [[[ 113
     Dr. Alan Stern
     FDA Perspective
     Dr. Michael Bolger

     EPA Perspective [[[ I23
     Dr. John Cicmanec

     Questions and Discussion: Toxicity and Risk Assessment ............................ 127
   Session Two:  Risk Management and Risk Communication

     A Review of Fish Consumption Advisories [[[ 135
     Dr. Robert Reinert

     Different People, Different Approaches: Risk Management and
     Communication in Minnesota [[[ 143
     Dr. Pamela Shubat

Conference Proceedings
     Mercury Deposition and the Activities of the Clean Air Act of 1990	173
     Ms. Martha Keating

     Great Lakes "Virtual Elimination" Initiative	179
     Mr. Frank Anscombe

     Minnesota Mercury Reduction Activities	185
     Mr. Pat Carey

     Questions and Discussion: National Mercury Study and Mercury
     Control Strategies	'	201
  Speakers' Biographies	205
  EPA Selected Publications	213

    List of Attendees
    Mercury Fact Sheets


                   National Forum on
     On September 27-29, 1994, the U.S. Environmental Protection Agency
sponsored a "National Forum on Mercury in Fish." Mercury is a ubiquitous
contaminant that occurs throughout the United States and the world Because
of mercury's potential to adversely affect human health, many state agencies
are monitoring fish tissues to determine how extensive mercury contamination
might be. More than 34 states have issued fish consumption health advisories
because of concerns about mercury contamination.

     The primary purpose of the workshop was to transfer "state-of-the-art"
information about mercury to states and other parties involved with risk
assessment and fish consumption advisories. A variety of topics were pre-
sented in several sessions:
     Session One
     Session Two

     Session Three
     Session Four
     Session Five
                      Mercury Overview and Background
                      Occurrence in Fish and Wildlife, Watershed Effects,
                      Florida Studies
                      Toxicity and Risk Assessment
                      Risk Management and Risk Communication
                      State Program Needs, National Mercury Study,
                      Mercury Control Strategies

     Within each session, individual presentations were followed by questions
from the audience and responses by the speakers. The Proceedings document
contains a summary of each speaker's presentation, a selection of key graphics,
and a summary of audience questions and responses.


                 National Forum on
Mercury in Fish
     The National Forum on Mercury in Fish was funded by the U.S. Envi-
ronmental Protection Agency.  The Standards and Applied Science Division in
the Office of Science and Technology (OST)—part of EPA's Office of
Water—sponsored the project. Mr. Rick Hoffmann, an environmental scien-
tist in OST, developed and organized the project. Ms. Charlie MacPherson
and Ms. Liz Hiett of Tetra Tech, Inc. provided essential logistical and editing
support throughout the project. Ms. Marti Martin (technical editor) and
Tetra Tech's Production Department provided editorial and production support.

     Members of the Steering Committee provided valuable assistance by
helping to shape the agenda and recruit speakers for the Forum.  Their help is
greatly appreciated. The Steering Committee members were Jerry Stober,
EPA Region 4; Philip Crocker, EPA Region 6; Martha Keating, EPA, RTP,
North Carolina; Brace Mintz, EPA OST; Mike Bolger, U.S. Food and Drug
Administration; Anna Fan, California EPA; Tom Atkeson, Florida Department
of Environmental Protection; Pam Shubat, Minnesota Department of Public
Health; and Don Porcella, Electric Power Research Institute. FDA also
assisted by providing supplemental funding.

     Finally, the  contributions of the invited speakers cannot be underesti-
mated since the success of the Mercury Forum depended on them. In later
evaluations of the Forum, numerous people complimented the high quality and
breadth of the presentations.


                  National Forum on
Welcome  and Introduction
James A. Hanlon
Deputy Director, Office of Science and Technology
U.S. Environmental Protection Agency, Washington, DC
Rick Hoffmann
Environmental Scientist, Office of Science and Technology
U.S. Environmental Protection Agency, Washington, DC
James A. Hanlon

         Mr. Hanlon welcomed the partic-
         ipants to the workshop and re-
         viewed some of the key aspects
of the mercury problem. He noted that
approximately 34 states had issued fish
consumption advisories at the time of the
conference; of those, advisories for 3 were
statewide in scope. At this point, research
is not complete enough to understand
completely how mercury reacts with the
environment. Consequently, mercury is a
"hot" topic in academic research, in pub-
lic debates, and in considerations by regu-
latory agencies. The public is pressing to
know what levels are considered safe.
     Mr. Hanlon explained that the
purpose of the conference was to assist
states and others interested in the mer-
cury contamination problem. He said,
"We are going to share what we know
about biological and chemical facts of
mercury and fate and transport. We will
talk about what we do not know. And we
will discuss various risk-related issues,
including risk management and current
Agency guidance."
     He further noted that the audience
was large and quite diverse. Many of the
participants were from state agencies, but
there were also representatives from a
large number of organizations.
Mr. Hanlon described the activities of
EPA's Mercury Task Force.
     The Office of Science and Technol-
ogy is in the process of developing a four-
volume set of guidance documents
regarding fish consumption advisory
programs. The series is titled Guidance
for Assessing Chemical Contaminant
Data for Use in Fish Advisories. Volume
1 (Sampling and Analysis) and Volume 2
(Risk and Assessment and Fish Consump-
tion Limits) have been issued. Volume 3
(Risk Management) and Volume 4 are
being developed.

Rick Hoffmann

     Mr. Hoffmann explained that the
conference was part of EPA's ongoing
commitment to assist states, which are
responsible for issuing fish advisories, by
providing timely and relevant technical
information and assistance about mer-
cury. The conference was designed with
two goals in mind: first, the immediate
needs of the end user and, second, the
broader national and international aspects
of the problem.
     Mr. Hoffmann briefly described the
state-by-state mercury fact sheets. They
illustrate that the problem is widespread
and hard to ignore. The fact sheets also
show that 50 states have 50 somewhat
different responses to the issue. Many
states are moving toward  a quantitative
risk assessment. Approximately 50
percent of the states issued risk-based
advisories, and the other half still used
advisories based on the FDA Action
Level for mercury. A map offish adviso-
ries shown by Mr. Hoffmann indicated
that 60 percent of the advisories were due
to mercury. An overlay of various poten-
tial sources of mercury illustrated that
mercury is pervasive in sediments.
Atmospheric sources are also important in
many locations.


                  National Forum on
                    Mercury In Fish
 Biogeochemical Cycling of Mercury:
 Global and Local Aspects
 William F. Fitzgerald
 Department of Marine Sciences, The University of Connecticut, Groton, Connecticut
 Environmental and Human
 Health Considerations

 ^^Biere is now much evidence docu-
  • menting tissue concentrations of
  M mercury (Hg) in marine and
 freshwater fish that exceed local,
 national, and international public health
 guidelines (e.g., Wiener et al.,1990;
 Eisler,1981). Moreover, nearly alt
 mercury in fish flesh (>95 percent)
 occurs as methylmercury (Westoo,
 1966; Huckabee et al., 1979; Grieb et
 al., 1990). Methylmercury compounds
 are considerably more toxic than
 elemental mercury and its inorganic
 salts.  Further, human exposure to
 methylmercury comes almost exclu-
 sively from consumption of fish and fish
 products, and prenatal life is more
 susceptible to brain damage than adults
 (Fitzgerald and Clarkson, 1991). The
 risk to public health is evident in the
 fish consumption advisories that have
 been issued by more than 30 states, the
 U.S. Food and Drug Administration
 (USFDA), the World Health Organiza-
 tion (WHO), and numerous govern-
 ments. Elevated levels of methylmer-
 cury in marine and freshwater
piscivorous fish pose an economic threat
to commercial and sport fishing indus-
tries, and the potential to adversely
affect fisheries.
    The environmental behavior and
accumulation of mercury in aquatic
 organisms is subtly complex and driven
 by chemical and biologically mediated
 reactions involving exceedingly small
 quantities of mercury in the atmosphere
 and natural waters. Indeed, an insidi-
 ously complicating feature of the
 mercury cycle in aquatic systems is the
 in situ bacterial conversion of inorganic
 mercury species to the more toxic
 methylmercury form. Recent work, for
 example, suggests that in many natural
 waters much of the methylmercury
 accumulating in biota, especially large
 fish, can be derived from the internal
 biologically mediated syntheses from
 inorganic mercury added to the aquatic
 system from external sources (for lakes,
 see Gihnour and Henry, 1991, and the
 Mercury in Temperate Lakes Program
 results as summarized in Hudson et al.,
 1994 and in Watras et al., 1994;  for
 estuaries and the open ocean, see Mason
 and Fitzgerald, 1990; Mason et al.,
 1993; and Rolfhus and Fitzgerald,
 1994). Atmospheric deposition is the
 principal external source of mercury to
 the oceans and most other natural
Atmospheric Cycling and
Deposition of Mercury

    The prominence of atmospheric
mobilization and depositional processes
in the global biogeochemical cycling of

                                                                   National Forum on Mercury in Fish
AIR 25 Mmol
98% Hg° Hge
2%HgP 1
       |AU.fLUXESlNMmel/y |
Figure I. The modern global mercury cycle (adapted from Mason et al.,
      The Global Mercury
      Cycle: Contemporary and
      Historical Views

           A mass balance view of the
      current global mercury cycle is
      presented in Figure 1, where the
      estimates for annual direct
      anthropogenic mercury releases
      to the atmosphere were averaged
      and taken as 4000 tons or, in
      megamoles (Mmol), 20 Mmol.
      Total emissions were taken to be
      7000 tons yr1  or 35 Mmol." A
      premodern  view of the global
      mercury cycle is presented in
      Figure 2 and corresponds to the
      1890 period. These simulations
      were adapted from Mason et al.
                      mercury is well recognized and described
                      in a variety of mass balance formulations
                      for the global mercury cycle. Environ-
                      mental assessments of source strengths
                      for natural and anthropogenic processes,
                      though often in error in early models, are
                      converging. Recently published budgets
                      for the atmospheric cycling of mercury, in
                      general, show human-related emissions of
                      mercury to the air as exceeding natural
                      inputs, with the principal sourcesbeing
                      coal combustion, smelting, and waste
                      incineration (Lindqvist and Rodhe, 1985;
                      Fitzgerald, 1986,1989; Nriagu and
                      Pacyna, 1988; Nriagu, 1989; Fitzgerald
                      andClarkson, 1991;LindqvistetaL, 1991;
                      Mason etal., 1994). Estimates for the
                      annual amounts of mercury released
                      directly into the air by human activities
                      rangebetween 3600 and 4500 tons, which
                      represents about 50 percent to 75 percent of
                      the total yearly input (6000 to 7500 tons) to
                      the atmosphere from all sources. This
                      adverse interference is larger because it is
                      now apparent that volatile elemental
                      mercury emissions from terrestrial and
                      marine systems include arecycled poll-
                      ution-derived component (Mason et al.,
     A comparison of the models
provides a revealing and insightful
assessment of the extent to which
anthropogenic mercury emissions
have perturbed the mercury cycle over
for the past century. Firstly, it is
evident that terrestrial systems, ocean
waters,  and the atmosphere are sig-
nificantly contaminated with mercury
released by human activities over the
100-year period considered in these
models. Secondly, the major role of
the atmospheric mobilization in the
mercury cycle and the associated
environmental impact is apparent
from the contemporary analysis
(Figure 1), where we find that local/
regional mercury emissions and
deposition (10 Mmol) are comparable
to the global contributions. That is,
about one-half of anthropogenically
related  mercury emissions  to the
atmosphere will be produced and
deposited on a local/regional scale,
while about one-half will contribute to
the global cycle.  Local deposition is
most probably due to the presence of
reactive mercury species and particu-
late mercury in flue emissions.

Conference Proceedings
 Elemental Mercury

      As illustrated, elemental
 mercury cycling plays a central
 role in dispersing mercury at the
 earth's surface and in affecting
 the synthesis and bioaccumula-
 tion of methylmercury in aqueous
 systems.  Production and evasion
 of elemental mercury in natural
 waters is a major feature of the
 biogeochemical cycling of
 mercury in fresh and marine
 waters. Our studies place oceanic
 emissions of elemental mercury
 at about 30 percent to 40 percent
 (10 Mmol) of the annual mercury
 flux to the atmosphere (Figure 1).
 Aquatic elemental mercury
 emissions are related to the
 availability and supply of reactive
 mercury (the Hg(II) substrate or
 reactant, Hg?) and, as noted, the
 atmosphere is usually the princi-
 pal source. Biologically mediated
 production of elemental mercury
 appears to predominate over abiotic
 mechanisms, and water-air recycling of
 anthropogenically derived mercury is
 significant. This reemission can exacer-
 bate adverse environmental effects.
 Indeed, the first-order view of the
 modem mercury cycle shows that
 approximately 70 percent of current
 oceanic emissions are of anthropogenic
     As part of the Hg(H)  substrate/
 reactant hypothesis, we proposed that
 the in situ production and efflux of
 elemental mercury could play a poten-
 tial buffering and/or amelioration role in
 aqueous systems (Fitzgerald et al.,
 1991). We hypothesized that in-lake
 biological and chemical production
 processes for elemental mercury and
 methylmercury compete with one
 another for reactant (HgR),  which we
 suggest is labile Hg(II) species. Our
 lacustrine and oceanic investigations
 support this unifying  physicochemical
paradigm. Evasion of elemental mercury
is balanced by total atmospheric deposi-
tion of inorganic mercury or reactant to
AIR 8 Mmol
98% Hg° H

                                        | ALL FLUXES IN Mmol/y |
2.  The pre-modera (ca. 1890) global! mercury cycle (adapted from
et al., 1994).
                                        the oceans. 'The mechanisms by which
                                        inorganic mercury is reduced to elemen-
                                        tal mercury are poorly known. However,
                                        the reduction appears to be biological
                                        and involve microorganisms.  In view of
                                        the significance of elemental mercury
                                        in affecting the speciation, behavior, and
                                        fate of mercury in the environment, the
                                        elemental mercury cycle in the atmo-
                                        sphere and waters deserves much
                                             There is a rapid equilibrium
                                        between the atmosphere and the surface
                                        ocean. When this phenomenon is
                                        coupled with the small sedimentation of
                                        mercury in the oceans, deposition on
                                        land becomes the ultimate sink for
                                        atmospheric mercury. Since the oceanic
                                        component is largely recycled, most of
                                        the anthropogenic mercury added to the
                                        system will be deposited on land and
                                        sequestered Into surface soils. Accord-
                                        ing to Lindqvist et al. (1991),  surface
                                        soils contain ca. 5,000 Mmol of mer-
                                        cury. The model projects an anthropo-
                                        genic mercury input at about 947 Mmol,
                                        which would represent about 15 percent
                                        of the total soil burden. Nater and
                                        Grigal's (1992) estimates of the net

                                              National Forum on Mercury in Fish
increase in mercury in surface soils from
the north-central region of the United
States were between 2 percent and 20
percent, and comparable to the model
estimate. Mercury accumulating in soils
is released slowly to terrestrial waters.
Swedish studies (Lindqvist et al., 1991;
Johansson et al., 1991; Aastrup et al.,
1991) and the Swain et al. (1992)
research on lakes in Wisconsin and
Minnesota suggest that less than 30
percent of the atmospheric mercury
deposition to a watershed reaches a lake.
As the Swedish workers have stressed,
the effects from the anthropogenic
mercury loading will persist for a long
period after a reduction in mercury
     We estimate that atmospheric
emissions have increased by about a
factor of 4.4 over the last century as a
consequence of human activities. Notice
that the net increase in the atmospheric
burden is a factor of 3, due to the
predicted rapid removal near of the
source of mercury emissions in the form
of particles and ionic species. As a
consequence, 60 percent of the direct or
recycled component is contributing to
the mercury background in the atmo-
sphere even though 77 percent of the
present-day inputs might be directly or
indirectly of anthropogenic origin (27 of
the 35 Mmol yr1). The 25 Mmol
mercury in the atmosphere represents an
average concentration of 1.6ngm"3,
which is comparable to the average
concentration of mercury over the
oceans (see Pacific data in Fitzgerald,
1989). Given this contemporary con-
straint, we predict that the preindustrial
atmosphere contained 8 Mmol of
mercury with an average concentration
of 0.5 ng nr3.
 Is Mercury Increasing in the

      A present-day rate of increase of
 atmospheric mercury at about 0.16
 Mmol yr1 is predicted by assuming that
 anthropogenic inputs have increased
 linearly over the last 100 years. Accord-
ingly, 1000 Mmol were emitted
anthropogenically during the 100-year
period. Of those emissions, 17 Mmol
are now in the atmosphere, 36 Mmol are
in the surface ocean, and the remaining
947 Mmol have accumulated in surface
soils. About 500 Mmol came from the
rapidly recycled anthropogenic compo-
nent and 447 Mmol via the atmospheric
cycle. The prediction that the present
rate of increase of mercury in the
atmosphere is about 0.16 Mmol yr1
(i.e., 0.6 percent yr1) is testable. For
example, atmospheric carbon dioxide
has been increasing at about half this
rate (i.e., 0.3 percent yr1).

     The elemental mercury and
methylmercury cycles are intimately
linked. Environmental studies of
mercury must view the biogeochemistry
of mercury as a unit and avoid a unilat-
eral focus on one aspect of the system.
For example, human exposure to
methylmercury in fish is related to
anthropogenic emissions of mercury,
especially elemental mercury, atmo-
spheric transport and deposition pro-
cesses,  and in situ biological interac-
tions and chemical reactions that lead to
elemental mercury production and
recycling between water and air.  Al-
though inorganic mercury reduction and
evasion remove mercury from the
waters where it might be methylated, the
recycling between surface waters and
the atmosphere will prolong the impact
of anthropogenically derived mercury
on aquatic systems. Present-day ocean
contains enhanced mercury levels that
promote increased methylation in the
water column. Oceanic emissions reflect
the presence of this increased burden.
About 70 percent to 80 percent of
today's emissions of mercury are related
to human activities. A substantial
portion of the emissions are predicted to
be deposited locally. Regional deposi-
tion would reflect the presence of ionic
and paniculate mercury species in
emissions. Elemental mercury emissions

Conference Proceedings
contribute to far-field and more global
effects, although polluted terrestrial
atmospheric conditions with elevated
concentrations of particles, ozone, and
sulfur gases may enhance the oxidation
and deposition of elemental mercury
(Munthe, 1992). A 3X increase in the
mercury burden in the atmosphere and
surface ocean is predicted.  Surface soils
contain most of the pollution-derived
mercury released over the past 100
years. Current emissions are exacerbat-
ing the problem by adding to seriously
contaminated active reservoirs of
surface soils, watersheds, the atmo-
sphere, and the  oceans. As most mer-
cury deposited on the oceans is recycled
to the atmosphere, the terrestrial envi-
ronment becomes a principal sink.
Mercury deposited on land is mobilized
slowly to enter the watershed and
tributaries of fresh and coastal waters.
The insidious consequence of the
complex and interesting biogeochemical
cycling of mercury is to lengthen  the
influence and active lifetime of anthro-
pogenic mercury in regions where
methylation can occur.
Future Research Directions

     As shown, the atmospheric and
aquatic biogeochemical mercury cycling
will be affected not only by localized
processes and discharges but especially
by emissions, airborne transport, and
deposition of mercury from regional and
longer range sources. The linkages
between atmospheric mercury emissions
and the accumulation of methylmercury
in fish have been recognized and
included in the U.S. 1990 Clean Air Act
Amendments, which require an assess-
ment of health risk to humans  and
wildlife caused by mercury emissions.
The potential adverse impact of atmo-
spheric mercury deposition to  the fresh
and marine waters ("The Great Waters")
is contained in a recent EPA report to
Congress (EPA-453/R-93-055, May
1994). Currently, we are expanding and
refining the modeling of the global
mercury cycle. The Mason et al. (1994)
study outlined in this paper used a one-
box atmospheric model to develop the
time-dependent evolution of mercury in
the atmosphere and surface ocean over
the past 100 years. A Global Mercury
Cycling Model (G-MCM) that will
provide a more realistic simulation of
the global scale dynamics of the atmo-
spheric, terrestrial, and oceanic mercury
cycle is being developed (Hudson et al.,
     Increasingly, environmental mer-
cury research is speciation- and reaction-
oriented. For example, inorganic mercury
(Hg(H)), elemental mercury (Hg°) and
alkylated mercury species (methylmer-
cury (mmHg), dimethyl mercury
(DMHg)) are being measured at pico to
femtomolair levels in air, water, and
precipitation. A new wave of exciting
and important environmental mercury
studies are beginning to yield coherent
models for the principal species and
reactions governing the behavior and fate
of mercury in nature. Much needs to be
done, and critical research areas include
(1)  establishing patterns of modem and
historic mercury deposition to provide an
essential foundation for detailed bio-
geochemical and ecological studies of
mercury; (2) assessing the contributions,
as well as the physical (i.e., particulate
mercury species) and chemical speciation
of global versus local/regional mercury
sources to terrestrial and oceanic regions;
(3)  identifying the reactions associated
with cycling of elemental mercury in the
atmosphere and natural waters; (4) exam-
ining atmosphere-water coupling and its
influence on methylmercury and elemen-
tal mercury cycling; (5) investigating the
mechanisms leading to the post deposi-
tional in situ bacterial conversion of
mercury species to methylated forms in
natural waters, wetlands, and watersheds;
and (6) relating human exposure to
methylmercury with the levels of lowest

     This work has been supported in
part by a grant from the National

      National Forum on Mercury in Fish
                     Science Foundation (Chemical Ocean-
                     ography Program) and partly by the
                     Wisconsin Department of Natural
                     Resources and the Electric Power
                     Research Institute.

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Mason, R.P., W.F. Fitzgerald, and
     F.M. Morel. 1994. Biogeochemi-
     cal cycling of elemental mercury:
     Anthropogenic influences. Geo-
     chemica Cosmochim. Acta
Mason, R.P., and W.F. Fitzgerald.
     1990. Alkylmercury species in the

Conference Proceedings
     equatorial Pacific. Nature 347:457-
Mason, R.P., and W.F. Fitzgerald. 1993.
     The distribution and biogeochemi-
     cal cycling of mercury in the
     Equatorial Pacific Ocean. Deep Sea
     Res. 40:1897-1924.
Mason, R.P., W.F. Fitzgerald, J. Hurley,
     A.K. Hanson, Jr., P.L. Donaghay,
     J. Sieburth.  1993. Mercury bio-
     geochemical cycling in a stratified
     estuary. Limnol Oceanog. 38:1227-
Munthe, J. 1992. The aqueous oxidation
     of elemental of mercury by ozone.
     Atmos. Environ. 26A: 1461-1468.
Nater, E.A., and D.F.  Grigal. 1992.
     Regional trends in mercury distri-
     bution across the Great Lake states,
     north central USA. Nature
Nriagu, J.O. 1989. A global assessment
     of natural sources of atmospheric
     trace metals. Nature 338:47-49.
Nriagu, J.O., and J.M. Pacyna. 1988.
     Quantitative assessment of world-
     wide contamination of air, water
     and soils by trace metals. Nature
Rolfhus, K.R., and W.F. Fitzgerald.
     1994. Linkages between atmo-
     spheric mercury deposition and the
     methylmercury content of marine
     fish. Water Air Soil Pollut.  In press.
Swain, E.B., D.R. Engstrom, M.E.
     Brigham, T.A. Henning, and P.L.
     Brezonik. 1992. Increasing rates
     of atmospheric mercury deposition
     in midcontinental North America.
     Science 257:784-787.
Trends '91. Carbon Dioxide Informa-
     tion Analysis Center, Oak Ridge
     National Laboratory.
Watras, C.J., N.S. Bloom, R.J.M.
     Hudson, S.A. Gherini, R. Munson,
     S.A. Claas, K.A. Morrison, J.
     Hurley, J., J.G. Wiener, W.F.
     Fitzgerald, R. Mason, G. Vandal,
     D. Powell, R. Rada, L. Rislow, M.
     Winfrey, J. Elder, D. Krabbenhoft,
     A. Andren, C. Babiarz, D.B.
     Porcella, and J.W. Huckabee.
     1994.. Sources and fates of mer-
     cury and methylmercury in Wis-
     consin lakes. In C.W. Watras and
     J.W. Huckabee, eds., Mercury as a
     Global Pollutant: Towards Inte-
     gration and Synthesis. Lewis
     Press, Boca Raton, FL, pp. 153-
Westoo, G. 1966. Determination of
     methylmercury compounds in
     foodstuffs I: Methyl mercury
     compounds in fish, identification
     and determination. Acta Chem.
     Scand. 20:2131-2137.
Wiener, J.G., R.E. Martini, T.B. Sheffy,
     and G.E. Glass. 1990. Factors
     influencing mercury concentra-
     tions in walleyes in Northern
     Wisconsin lakes. Trans. Amer.
     Fish.Soc. 119:862-870.

National Forum on Mercury in Fish
               Mercury in the Environment
             • Volatile
               Readily mobilized

               Significant anthropogenic interferences

               Transformations to more toxic species,
               e.g., Monomethylmercury

              • Bioamplification,  e.g., fish
             • Human health hazard
                Conclusions and Predictions

                Anthropogenic activities have increased
                atmospheric Hg emissions by a factor of
                3 relative to natural emissions.
                  1/2 emissions—^-global atmospheric cycle
                  1/2 emissions—^-deposited locally/regionally

               • Anthropogenic Hg emissions for past
                100 years are contained in active
                reservoirs at the Earth's surface. Of the
                estimated 1000 Mmoles emitted, there
                  17 Mm atmosphere! S:anificant
                  36 Mm oceans    L Significant
                  947 Mm soils    J Contaminant

               »Terrestrial soils are the principal
                repository for anthropogenic Hg—Hg is
                slowly but continuously released to fresh
                waters and the coastal zone.

Conference Proceedings
                   Conclusions and Predictions

                  »Hg concentrations in the atmosphere and
                    ocean surface waters have increased by
                    a factor of 3. Soils have increased their
                    Hg content by about 15%.
                      Continued anthropogenic Hg emissions on
                      both a local and global scale are increasing Hg
                      in active reservoirs at the Earth's surface.

                  • Cessation of Hg fluxes associated with
                    human activities will lead to a relatively
                    rapid decrease in Hg contained in the
                    atmosphere and ocean surface waters.

                  ••Unfortunately, the release of stored
                    anthropogenic Hg in soils will continue
                    for a long period—decadal time scale
                    after emission reductions are
                    implemented (cf. Swedish experience).
 Taken from Hudson et.al., 1994.

                                                  National Forum on Mercury in Fish
               Little Rock Treatment Basin
                      Atmospheric Deposition
                             1.1 g/yr
                         Trophic Transfer
|5 % of Total Inputs|
                                          0.06 gfrr
                                                       Taken from Fitzgerald ct.al., 1991.
    Methyl-Hg in Little Rock Lake, Wl (Bloom et al., 1991)
                   D.O. (met)
                             10   13
           June 15.1983
           0    3   4   f   0  10   13
                               0   3   4   •    0   10   13
2 '

4 '


• •

            Augusts, 1988
                                          October 9, 1989
                 1     3     3

Conference Proceedings
         Atmospheric Deposition
             1 x 107  moVyr
        e  Ocean
              River Inputs
             1 x 106 moVyr
             5.3 x 105 rnoj/yr
                 Trophic Tr.ansfer
      IL9 % of Total Inputs
             2.2x10  maj/yr

                       Taken from Rolfhus and Fitzgerald, 1994.
     Natural and Anthropogenic
                    Natural and Anthropogenic
Biological Incorporatic

   Transport of atmospherically-derived H^2to the biologically
   productive Pacific Ocean.  Atmosphere/ocean circulation and
   biogeochemical model for the production and accumulation of
          * in oceanic fish.

                                               National Forum on Mercury In Fish
                  Equatorial Pacific  Ocean
          o   2BO  500 750 mnn
       200 •
    g  400-
                                 1   ?  3  4   5
                                      Reactive Hg
                                       Station 4
                                                20	40
                                                       35.5      37.S
              • ^   r   •
Taken from Maion aod Fitzgctald, 1990.
                                            0   6.7
  S (o/oo)
                           Predictions—to Test

                  1. Atmospheric Hg concentrations are increasing
                    at about 0.6% (yr1)

                  2. On average, soils contain about 15%
                    anthropogenic Hg

                  3. Expect about a factor of 3 increase for Hg
                    deposition in locations that are relatively free of
                    localized emissions and deposition

                  4. Hg (MMHg) in ocean fish has increased by
                    about a factor of 3

                  5. Hg (MMHg) in fresh water fish has on average
                    increased by a factor of s£ depending on
                    location and type of water body (localized
                    impact and drainage)

                  6. About 1/2 anthropogenic Hg emissions enter
                    the global cycle as Hg°
                     About 1/2 anthropogenic Hg emissions are
                     deposited locally/regionally as Hg**

                 National Forum on
                    Mercury in Fish
Aquatic Biogeochemiistry and
Mercury Cycling  Model  (MCM)
Donald B. Porcella
Electric Power Research Institute, Palo Alto, California
        Mercury concentrations in
        marine and freshwater fish
        often exceed human consump-
tion health advisory limits, even in areas
remote from known mercury sources.
Atmospheric deposition, transformed to
methylmercury, can account for virtu-
ally all of the mercury in fish in these
environments. This is part of the natural
biogeochemical cycle of mercury from
the earth's surface to the air and back
again. Human activities have mobilized
much of this mercury, and sources to the
atmosphere include both natural and
anthropogenic components. Anthropo-
genic sources vary extensively histori-
cally as well as spatially and have
included waste incineration; fossil fuel
combustion; chloralkali plants; ore
extraction, roasting, and smelting;
precious metal extraction; and many
other activities.
     These activities contribute addi-
tional mercury to the natural sources of
mercury.  Not all of the mercury enter-
ing aquatic ecosystems is taken up by
fish.  Most mercury enters the sediment
pool, and  a small fraction is transformed
to methylmercury and enters the biotic
pool.  Except when point sources
contribute excessive mercury, the
amount of mercury accumulated by fish
does not affect fish growth and survival,
but represents a risk to  humans and
other organisms, especially bird and
mammal fish-eaters. To assess these
risks, we need to calculate the amount
of mercury accumulated by fish from
their aquatic environment, either via
uptake of aqueous mercury or via the
food chain.
    As part of the Mercury in Temper-
ate Lakes (MTL) and Mercury Accumu-
lation Pathways and Processes (MAPP)
projects in northern Wisconsin, investi-
gators studied seven low-productivity,
dilute water seepage lakes that spanned
a range of pH and dissolved organic
carbon (DOC) concentrations. A major
objective was to develop a simulation
model to calculate fish mercury concen-
trations. This task required algorithms
to estimate net methylation of mercury,
especially since virtually all of the fish
mercury is present as methylmercury.
Among reasons for developing a simula-
tion model to assess mercury  in fish, the
following seem most important:
(1) eating fish is the chief mode of
exposure for humans and animals;
(2) fish primarily accumulate methyl-
mercury, produced from a complex
mercury cycle with many influence
factors that vary widely in surface
waters; (3) water concentrations of
mercury represent many sources that
enter the surface water via multiple
pathways (ground and surface waters,
deposition); and (4) mercury is present
at ultra-trace concentrations (nano and
picomolar), and models can provide an
initial default assessment while helping

                                                             National Forum on Mercury in Fish
 Hg in fish, ug/g ww
       r	T	r
Pallotlo Vandercook Crystal     LRR
Figure 1. One-year-old whole yellow perch from northern Wisconsin
  Dissolved methyl-Hg, ng/lifer
              -0.13 + 0.19x  RSQ = 0
                           Total Mercury, ng/liter
Figure 2. Mercury in seven northern Wisconsin lakes.

                      to define the most cost-effective sam-
                      pling design for studying a surface
                           Seepage lakes are dominated by
                      atmospheric deposition and receive
                      virtually all of their water, nutrients, and
                      mercury from atmospheric deposition.
                      The MTL/MAPP lakes are close to-
                      gether, and we suspected that they
                      received the same mercury deposition,
                      but the mercury levels bioaccumulated
                      by fish varied over a factor of 10
             (Figure 1). This observa-
             tion reinforced the need
             for a model capable of
             dealing with the varying
             conditions leading to the
             tenfold difference in
             mercury fish concentra-
             tions.  Simplistic relation-
             ships such as regressions
             between methylmercury
             and total mercury in water
             (Figure 2) or between fish
             mercury and methylmer-
             cury in water (Figure 3),
             although applicable in
             these seven lakes, were
             not capable of application
             to other sites.  Further-
             more, the results show
             that the role of inputs, in
             this case deposition,
             remains unclear because
             of the indirect nature of
             transformation and
             bioaccumulatiori. This
             result is reinforced by the
             observation in Minnesota
             that while mercury
             deposition has decreased
             by a factor of 3 since the
             1950s, fish mercury
             concentrations have not
             changed in response.
                  Intensive field
             studies during MTL/
             MAPP led to a conceptual
             model (Figure 4) that
             shows the importance of
             loading (deposition, water
             inflows), transformation
             (presence of wetlands,
             sulfate-reducing bacteria,
reduction, sorption, food chain dynam-
ics, water quality, and nutrient status),
and loss (evasion, sedimentation, and
outflows). This conceptual model was
codified in a mathematical model called
the Mercury Cycling Model (MCM)
(Figure 5). The MCM runs with a
monthly timestep  and is bounded by the
atmosphere, the lake margins, and the
lake sediment margins at the deep
sediment layer. Reactions in the
watershed and the atmosphere are not

Conference Proceedings
 modeled; concentrations
 are measured to provide
 input at the boundary.
      All three major
 species of mercury—
 elemental mercury (Hg(0)),
 inorganic mercury (Hg
 (II)), and methylmercury
 (CH3Hg+)— are tracked in
 MCM in three physical
 compartments: the mixed
 layer (epilimnion), the
 hypolimnion, and the
 sediments. At one time
 dimethylmercury was
 considered as a possibly
 important chemical
 species, but so far, it has
 only been observed in
 marine environments.
 Four biotic compartments
 were defined, comprising a
 linear food chain occur-
 ring in the two layers of
 water: phytoplankton,
 zooplankton, a forage
 fish, and fish that prima-
 rily consume other fish.
 Although simulation
 output can include any
 variable, the target of
 interest is mercury in
 predatory fish because
 these fish represent the
 greatest potential expo-
 sure to other consumers
 outside the model bound-
 aries (birds, humans, other
 mammals). Physical and
 chemical influences on
 mercury transport and
 speciation are also mod-
 eled. The MCM has a
 user-friendly interface and
 runs on a Macintosh
     The model can
 simulate the mercury
concentrations in the biotic compart-
ments quite well (Figure 6). Further-
more, in a more rigorous test, the model
can simulate the major mercury species
(elemental mercury, inorganic mercury,
and methylmercury) very accurately
                            mg/kilogram, wet weight
                                                   methyl-mercury, ng/liter
                          Figure 3. Mercury in one-year-old yellow perch.
                         Figure 4. Important processes affecting mercury in surface waters.
                                       (Figure 7).  These results suggest that
                                       the MCM provides a very accurate tool
                                       for assessing the effects of mercury
                                       deposition on mercury bioaccumulation
                                       by fish in these lakes, thereby allowing
                                       users to ask "what if questions that are

      National Forum on Mercury in Fish

Figure 5. Mercury cycling model.
  CH3Hg (ppm)
                                   Predaceous fish QAge 4
                                    (Yellow Perch)
                       Forage fish
                (age 1 Yellow Perch)
                         Simulate^ CH3H9
Figure 6. Mercury cycling model simulates biotic compartment concentrations.
                      difficult if not impossible to accomplish
                           Some of these questions are
                      illustrated in Figure 8. This figure
                      shows the baseline condition for mer-
                      cury in predatory fish, modeled in the
                      reference basin (unacidified) of Little
                      Rock Lake, one of the seven northern
                      Wisconsin lakes studied in MTL. The
                      annual cycle of mercury in fish repre-
            sents the seasonal changes
            hi the ratio of two pools—
            fish biomass and the
            mercury in fish.  The
            upper curve in Figure 8,
            showing an increase in
            fish mercury concentra-
            tions, represents what
            would happen if the
            particulate matter in the
            lake (clays, detritus, other
            small particles) were
            reduced by a factor of 10.
            Less particulate matter
            means that less mercury is
            bound, making more
            available for methylation
            and subsequent uptake.
            The lower curve in Figure
            8, showing a decrease in
            fish mercury concentra-
            tions, represents  what
            would happen if we could
            increase the rate  of
            demethylation by a factor
            of 2.  Faster demethyla-
            tion would lead to less
            methylmercury available
            for uptake through the
            food chain. The fourth
            curve differs little from
            the base case and results
            from a 5 percent decrease
            in deposition.  Such a
            decrease is the maximum
            expectation of what might
            result from control of
            power plant emissions.
                 Although these
            changes are apparent in
            the simulations, they are
            not substantial.  In fact,
            the changed fish concen-
trations do not begin to approach the
new steady state levels until after 7-8
years.  One of the factors driving the
fish accumulation appears to  be
sediments as a reservoir of substrate
for methylation and release to overly-
ing waters where biota can accumulate
the methylmercury.  The mercury in
sediments has built up over time and
can affect rates of recovery when

 Conference Proceedings
 loading is reduced.  If
 we simulate removal of
 all mercury-containing
 sediments from one of
 the MTL lakes, a rapid
 reduction in fish mer-
 cury is observed, result-
 ing in a 50 percent
 reduction within 10
 years (Figure 9). A new
 steady state is not
 reached for about 30-50
 years, varying with lake
 site-specific conditions,
 like the rate of buildup
 of mercury in the sedi-
     The MCM has  been
 applied to a variety of
 lakes: OnondagaLake
 (using USEPA's
 MERC4 model, a PC-
 based version of the
 MCM embedded in
 modeling framework),
 the seven Wisconsin
 lakes, one of the
 Adirondacks lakes, and
 in the Great Lakes
 (Superior and Erie).
 New studies will apply
 the MCM to a Florida
 seepage lake, where a
 subtropical climate will
 be simulated.  The
 model has use in hypoth-
 esis testing/definition,
 constraining of rate
 constants for different
processes, the evaluation
 of alternatives, the
 design of field studies,
 and the evaluation of
uncertainty. Additional
applications will increase the robust-
ness of the model and its coefficients.
Modifications to the MCM presently
include use in global mercury cycling,
regional lake modeling, and more
complex food web/bioenergetics
simulation algorithms.
     The field studies and model
results show the importance of mercury
                        Observed [HgfOfl and [CH, Hg]
                          0.1                  0.2
                                                      Units, ng/Q
                             Observed [Hg(U)]
Figure 7. Mercury cycling model simulates mercury species measured
Wisconsin lakes.
                             in seven
 CH3Hg (ppm wet)
                                              Decrease in
                                              detrital particles
                                                               Base case
                    Increase in
         5% decrease -
Figure 8. Piscivorous fish mercury—model result!!.
              speciation and of site-specific factors in
              controlling accumulation of mercury in
              fish.  Furthermore, sediments seem to
              be the major factor controlling mercury
              bioaccumulation by fish. The effects of
              sediments and other site-specific factors
              help explain why fish mercury concen-
              trations are not directly coupled to
              mercury inputs.

                                                             National Forum on Mercury in Fish
  CH3Hg (ppm wet)
Figure 9.  Piscivorous fish mercury.

                     Benoit, J.M., W.F. Fitzgerald, and
                         A.W.H. Damman. 1994.  Histori-
                         cal atmospheric mercury deposi-
                         tion in the mid-continental United
                         States as recorded in an
                         ombrotrophic peat bog. In C. J.
                         Watras and J.W. Huckabee, eds.,
                         Mercury as a Global Pollutant, pp.
                         187-202.  Lewis Publishers, Ann
                         Arbor, MI.
                     Fitzgerald, W.F. 1986. Cycling of
                         mercury between the atmosphere
                         and oceans. In The Role of Air-
                         Sea Exchange in Geochemical
                         Cycling, pp. 363-408.  NATO
                         Advanced Science Institutes Series
                         C (P. Buat-Menard, ed.). Reidel,
                         Dordrecht, Netherlands.
                     Fitzgerald, W.F., R.P. Mason, and G.M.
                         Vandal.  1991. Atmospheric
                         cycling and air-water exchange of
                         mercury over mid-continental
                         lacustrine regions. Water Air Soil
                         Pollut. 56:745-768.
                                                        Hudson, R.J.M., S.A. Gherini, C.J.
                                                            Watras, and D.B. Porcella.  1994.
                                                            Modeling the biogeochemical
                                                            cycle of mercury in lakes: The
                                                            Mercury Cycling Model (MCM)
                                                            and its application to the MTL
                                                            study lakes. In C.J. Watras, and J.
                                                            W. Huckabee, eds., Mercury as a
                                                            Global Pollutant, pp. 473-523.
                                                            Lewis Publishers, Ann Arbor, ML.
                                                        Porcella, D.B.1994. Mercury in the
                                                            environment: Biogeochemistry. In
                                                            CJ.Watras, and J.W. Huckabee,
                                                            eds., Mercury as a Global Pollut-
                                                            ant, pp. 1-19.  Lewis Publishers,
                                                            Ann Arbor, MI.
                                                        Watras, C.J., N.S. Bloom, RJ.M.
                                                            Hudson, S.A. Gherini, R. Munson,
                                                            S.A. Claas, K.A. Morrison,
                                                            J.Hurley, J.G. Wiener, W.F.
                                                            Fitzgerald, R. Mason, G. Vandal,
                                                            D. Powell, R. Rada, L. Rislove,
                                                            M. Winfrey, J. Elder, D.
                                                            Krabbenhoft, A.W. Andren, C.
                                                            Babiarz, D.B. Porcella, and J.W.
                                                            Huckabee.  1994.  Sources and

Conference Proceedings
     fates of mercury and methylmer-
     cury in remote temperate lakes. In
     C.J. Watras, and J.W. Huckabee,
eds., Mercury as a Global Pollut-
ant, pp. 153-177. Lewis Publish-
ers, Ann Arbor, MI.


                  National Forum on
                     Mercury in Fish
 Mercury Methylation In  Fresh
Cynthia C. Gllmour
Assistant Curator, Estuarine Research Center, The Academy of Natural Sciences
St. Leonard, Maryland
        Mercury methylation is a pre-
        dominantly microbial process
        that occurs mainly in anoxic
sediments and waters, with maximum
intensity often at the interface between
anoxic and oxic conditions (O/A bound-
ary) (Gilmour and Henry, 1991; Winfrey
and Rudd, 1990).  Understanding of the
geochemistry and microbiology of
methylation has progressed rapidly in the
last few years. Two major changes have
helped this progress: (1) the finding that
sulfate-reducing bacteria (8KB) are
important mediators of methylation; and
(2) improvements in mercury analysis that
have allowed measurement and speciation
of mercury at ambient levels.
     Of critical importance in this
research is the relationship between
mercury inputs, or concentrations, and
resultant methylmercury concentrations
and bioaccumulation. However, mercury
concentration is only one of many
variables that need to be considered in
order to model methylmercury bioacc-
umulation. Have mercury levels in fish
increased as a result of increased mercury
deposition  over time? Or does the
biogeochemistry of certain types of
aquatic systems predispose them to net
mercury production and bioaccumulation?
Are the changes in the biogeochemistry of
some lakes due to acid deposition the
cause of increased mercury
bioaccumulation? Each of these factors
no doubt plays a role. The following
discussion will highlight some of the
important factors in this very complex set
of relationships, particularly control of
methylation rates.
Methylmercuiy Budgets for
Three Lakes

     Budgets have been constructed in
the past few years for a small number of
aquatic systems using appropriate
noncontaminating methods for mercury
speciation. New methods for estimating
reactions and fluxes have also been
applied as part of these studies. The
biogeochernical cycles put together for
these lakes demonstrate the state-of-the-
art understanding of mercury and meth-
ylmercury biogeochemistry.

Littie Rock Lake,  Wisconsin

     Little Rock Lake is a small, pristine
seepage lake. Studied intensely (e.g.,
Weiner et al., 1990; Watras et al., 1994),
the Little Rock Treatment (LRT) basin is
the lake on which the MTL model was
originally based. Little Rock Lake was
partitioned in 1984 and one basin acidi-
fied with sulfuric acid over 6 years.  We
and others have developed methods in the
last year or two to fill in some of the
previously unmeasured parameters in the
methylmercury budget. These methods
include noncontaminating methods for

      National Forum on Mercury in Fish



Sosrmnl efflux
804 e*

10 OV

0.1 ug/m2/y
0,01 o/»

0.12 ng/t

Scdfenent eccumuiatJon rate

5 ng/g
0.02 g

Sediment trap flux
5.4 ug/m2/y

Sediment concentration
0.5 ng/g at surface
0.05 g

Figure 1. Budget for methylmercury in Little Rock Lake treatment
basin modified from Watras et al., 1994. Modifications were based
on our measurements of nonadvective flux of methylmercury from
sediments and on methylmercury production rates and concentra-
tions within sediments. Sediment methylation rate, and methyl-
mercury concentration, accumulation, and efflux rate were modi-
fied; all other data are from Watras et al., 1994. Sediment
concentrations and methylation rate are given in ng/g wet weight
sediment. Rate calculations assume a 120-day warm season and
1 mm/y sediment accumulation rate.  De novo methylation ap-
peared to occur to at least 8 cm depth although it was maximal in
the top 4 cm (Gilmour, 1994).

                       estimation of nonadvective flux from
                       intact sediment cores, and the use of
                       mercuric chloride with a specific activity
                       high enough to be used as a tracer (rela-
                       tive to bulk mercury) to estimate ambient
                       methylation rates for the first time.
                            A revised methylmercury budget for
                       LRT, based on a few estimates of methy-
                       lation rate and sediment/water methylmer-
                       cury flux in 1993, is shown in Figure 1.
                       The primary site of de novo methylmer-
                       cury production appears to be sediments.
                       Methylation rates in the top 1 mm of
                       sediments averaged about 2.5 ug/mVd in
                       mucky treatment basin sediments.
                       Sediments constitute the main pool of
                       methylmercury in the lake if the top few
                       centimeters are considered, and fish are
                       another important pool. Efflux of methyl-
mercury from sediments was a small
fraction of total methylmercury produc-
tion within sediments, suggesting intense
demethylation across the sediment/water
interface, or recycling of methylmercury
within sediments.  Recycling of methyl-
mercury in the water column is very
important in its mass balance, with annual
sediment trap fluxes of approximately 10
times the level of methylmercury efflux
and approximately equal to de novo
methylmercury production in the top
1 mm of sediment. Although deposition
and de novo methylmercury production
are approximately equivalent in the top
1 mm of sediment, methylation occurs to
at least 8 cm sediment depth.  In LRT,
sulfate stimulates sulfate reduction,
methylmercury production in and efflux
from sediments. In these high-organic-
carbon sediments, sulfate reduction is
limited by sulfate, as it is in most sedi-

Pattetie Lake, Wisconsin

     Pallette Lake is a nearby pristine
seepage lake.  As in LRT, the primary site
of de novo methylmercury production
appears to be littoral sediments. The oxic/
anoxic interface in the water column is
also a source of methylmercury, however.
De novo production occurs just below the
O/A interface in the zone of maximal
sulfate reduction (Figure 2) (Watras et al.,
1995). Methylation and sulfate reduction
do not occur in hypolimnetic waters or
sediments after sulfate is depleted in
spring. In epilimnetic and littoral sedi-
ments, sulfate reduction and methylation
are limited by organic carbon, not sulfate.
This is not generally the case. Because of
this limitation, sites of organic carbon
production and advection (such as ground
water inflow zones) and sites of high
photosynthetic production (like the
pycnocline) are primary sites of methyl-
mercury production in this organic-
carbon-limited system.
     I want to emphasize the importance
of the O/A interface in methylmercury
production, and its location.  A suite of
microbial processes occurs across this
gradient, with electron acceptors (e.g.,

Conference Proceedings
oxygen, nitrate, sulfate) being supplied
from the oxic side, and organic substrates
being sequentially oxidized with depth.
Chemo- and phototrophic processes are
often maximal here, with the availability
of reduced substrates like HS-. Under
oxic waters, the O/A interface is usually
within a few millimeters to centimeters of
the sediment surface. With the formation
of a hypolirnnion, the O/A interface and
its microbial strata move into the water
column. Methylation occurs all along this
interface, and this is well illustrated in
Pallette Lake.

Onondaga Lake, New Yoik

     Onondaga Lake is a very different
system. It is a large, eutrophic, alkaline,
heavily mercury-polluted drainage lake
(Henry et al., 1995).  The main in-lake site
of methylmercury production is the
anoxic hypolirnnion. Sulfate concentra-
tions are extremely high for a freshwater
lake, and sulfate does not become de-
pleted in the hypolimnion over the
summer. External sources of methylmer-
cury, especially wastewater treatment
effluent, and streams flowing through
contaminated ground, are important
inputs. Efflux of methylmercury from
sediments, especially hypolimnetic and
contaminated sediments, is substantial
relative to the pristine lakes discussed
above, but is still a minor source to the
Microbiology of Methylation

     Work in a number of lakes and
estuaries has shown that SRB are impor-
tant mediators of methylmercury produc-
tion in sediments and in anoxic waters.
Compeau and Bartha (1986) first showed
their importance in mercury methylation
in estuaries, and this was extended to
fresh waters in 1992 (Gilmour et al.,
1992). This work was done using specific
inhibitors (molybdate) and stimulants
(short-chain fatty acids) of SRB. The
distribution of methylating activity in
aquatic systems generally matches that of
sulfate-reducing activity—-just below the
                         -»-  StiHato reduction
                         0       tOO     200
                                       |  Bacteria
                                         25     0
(I   SO   100   2.0
MB methylation     _o_
                              (rnmol C/m'-d)
                                                   SO      100
Figure 2.  Biogeochemical process rates and microbial abundances
from in situ incubations in Pallette Lake.
O/A interfaces both in sediments arid the
water column, and in anoxic waters where
sulfate is available. Nevertheless, other
organisms may also contribute to mercury
methylation. Molybdate does not always
block all methylation; it does not affect
methylation at all in a few systems. The
role of other organisms in methylation
and the type of organisms involved are
poorly defined.
     Why do SRB methylate mercury?
Mercury methylation is not a defense
mechanism against mercury for SRB.
Methylation is constitutive (not inducible
by mercury), and the ability to methylate
mercury does not confer added mercury
resistance among SRB.  Only a subset of
SRB methylate mercury. We have
hypothesized that Hg-S species, which
generally dominate dissolved mercury
speciation in areas of methylation, are
available to SRBs for methylation,
possibly through metal uptake media-

       National Forum on Mercury in Fish

                      nisms developed by these organisms for
                      sulfitic environments. SRB do not contain
                      the mer operon system, a plasmid-
                      encoded mercury defense mechanism
                      found in many aerobes that codes for
                      mercury and methylmercury uptake,
                      demethylation, and reduction (Henry,
                      1992). However, there is some evidence
                      that there is an oxidative methylmercury
                      decomposition system in 8KB (Oremland
                      etaL, 1991).
                      Factors That Affect
                      Methyimercuiy Production in

                           1. Total mercury concentration.
                      Although increased mercury inputs to a
                      system generally result in increased
                      methylmercury in fish, the quantitative
                      relationship between mercury concentra-
                      tion and methylation is not linear. In one
                      type of bacterial culture, methylation is a
                      function of the log of the total mercury
                      concentration (Figure 3). This illustrates
                      that it is not the total mercury concentra-
                      tion, but the concentration of mercury
                      available for methylation, that needs to be
                      known to estimate methylation rates.
                      Mercury-sulfides are the dominant
                      dissolved Hg(E[) species in most waters;
                      even oxic waters often contain nM HS~.
                      Ionic Kg2*" concentrations are infinitesimal
                          Ho added, mgf
Figure 3. Concentration dependence of mercury methylation by
sulfate-rcducing strain ND132, in sulfate-reducing medium, which
can contain up to mM sulfide concentrations.
(< 10'30 M), and the free ion is probably
not the main biologically active species.
     A comparison of mercury and
methylmercury concentrations and percent
methylmercury among the three lakes
(Table 1) shows that (1) mercury concen-
tration in the water column is not a linear
function of mercury in sediments and
(2) percent methylmercury in the water
column, either epi- and hypolimnia, is
similar among the lakes, but percent
methylmercury in sediments is not.
Clearly, there  is not a linear relationship
between mercury loadings and methyl-
mercury concentrations among the
systems.  Along with microbial activity,
mercury solubility and speciation in
sediment pore waters probably determines
methylation rate in sediments. We are
investigating sediment/pore water parti-
tion coefficients and mercury speciation in
pore waters in these and other lakes  as a
tool to predict methylmercury production.
     2. Lake  chemistry/morphometry.
Factors that are predictive of mercury
levels in fish include low pH, high
dissolved organic carbon  (DOC),
reservoir formation,  and stratification.
The presence of an anoxic hypolim-
nion allows flux of inorganic mercury
from  sediments; methylmercury
degradation is minimal in anoxic
waters; and methylmercury flux from
sediments appears to be increased. In
addition, methylmercury can be
formed in anoxic waters if sulfate is
not depleted  (e.g., Onondaga). In
lakes  where sulfate is depleted from
the hypolimnion, methylation may
occur at  the O/A interface (e.g.,
Pallette). Methylmercury formed in
the water column may be more avail-
able for bioaccumulation than meth-
ylmercury formed within  sediments.
There is  little information on how
DOC  may affect methylation rates
directly at this time,  although DOC
amount and character do influence
dissolved mercury speciation and
hence availability for methylation.
     Low-pH lakes are especially
susceptible to mercury problems. The
Little  Rock Lake study showed that
sulfuric acid acidification alone resulted

 Conference Proceedings
 Table 1. Comparison of total mercury (Hg) and methyhnercury (MeHg) concentrations, and methylmercury as
 a percent of total mercury (%MeHg) in oxic and anoxic waters, and sediments of three lakes. Water column
 values are for dissolved (<0.2 um) concentrations.  Sediment concentrations are per g dry weight
Little RockTreatment



<0. 1-0.25


up to 100%







 in increased mercury in fish (Wiener et
 al., 1990). Increasing sulfate levels,
 rather than pH per se, may be one
 component of how pH influences
 methylmercury production and bioacc-
 umulation. The changes in mercury
 accumulation in LRT were attributed to
 increases in methylmercury production,
 primarily in sediments (Winfrey and
 Rudd, 1990).  Increases in sediment
 sulfate reduction rates in lakes impacted
 by sulfate deposition are well docu-
 mented, and this was also shown to
 occur in LRT relative to LRL. It is
 important to recognize that low pH in
 lake water does not usually mean
 decreased pH in sediment pore waters,
 or inhibition of microbes.  Sulfate
 reduction is a strong alkalinity genera-
 tor.  In LRT sediments, we found that
 increased sulfate levels stimulated both
 production of methylmercury within and
 efflux from sediments.  However,
 sulfate does not consistently stimulate
 mercury methylation in sediments; in
 some cases SRR is not sulfate-limited
 (e.g., Pallette), and at high sulfate levels
 sulfide production by SRB appears to
 limit the availability of mercury for
     We have examined the relationship
between sulfate levels in lake water and
methylmercury levels in sediments in a
number of lakes and estuaries and have
found the pattern shown in Figure 4.
Methylmercury is plotted as a percent-
age of total mercury to compensate for
variations in total mercury among lakes.
The hypothetical relationship between
sulfate concentration and percent
 methylmercury across a wide range of
 sulfate and salinity is shown in Figure 5.
 This is an evolving relationship.  We are
 in the process of adding information
 from Wisconsin lakes to the graph to see
 if the pattern still holds.  We are also
 examining other ways of looking at the
 relationship, especially adding in more
 details of mercury speciation and
      Reservoirs are also susceptible to
 mercury bioaccumulation. Microbial
 activity,  and hence methylation, may be
 high in newly formed reservoirs because
 labile organic matter concentrations are
 high. Reservoir formation and its
 effects on the mercury cycle are cur-
 rently being studied by a group in the
 Experimental Lakes Area, Ontario.
 Wetlands have recently been recognized


O Hudson River Estuary
(• Mass. Reservoirs
13 Cape Cod Ponds
!• NC Reservoir
A Paliette Lake
A Little Rock Lake A
A * A'
• • * t o oo .
cF ' o R)
' • • • i ' • • • i i i 1 1 1 v> — iii| — i — i 1 1 1 — i — i 1 1 [
1 10 100 . 1000 10000 100000
Sulfate reduction rate, umoles m"2 d'1
Figure 4. Relationship between percent methylmercury and
sulfate reduction rate in the top 4 cm of sediment in eight lakes
and along the salinity gradient of an estuary.

      National Forum on Mercury in Fish
                        log sulfate reduction rate
Figure 5. Hypothetical relationship between sediment sulfate
reduction rate and the percent of total mercury hi the methylated
                      as sites of high methylmercury produc-
                      tion, perhaps for the same reasons (St.
                      Louis et al., 1994).
                           Lake surface-to-volume ra,tio
                      affects methylmercury accumulation
                      (Bodaly et al., 1993). A relatively high
                      surface area of warm, shallow sedi-
                      ments increases microbial activity.
                      Temperature seems to affect methyla-
                      tion more strongly than demethylation.
                      Lake hydraulic retention time is also
                      important, with long-retention-time
                      lakes accumulating more methylmer-
                      cury from sediments.

                      Bodaly, R.A., J.M.W. Rudd, RJ.P. Fudge,
                           and C.A. Kelly. 1993. Mercury
                           concentrations in fish related to the
                           size of remote Canadian Shield
                           Lakes. Can. J. Fish. Aquat. Sci.
                      Compeau, G. and R. Bartha. 1985.
                           Sulfate-reducing bacteria; principle
                           methylators of mercury in anoxic
                           estuarine sediment. Appl. Environ.
                           Microbiol. 50:498-502.
                      Gilmour, C. C. 1994. Comparison of
                           sediment Hg methylation rates and
     the contribution of sediment MeHg
     production to the MeHg mass
     balance among ecosystems. Pre-
     sented at the International Confer-
     ence on Mercury as a Global
     Pollutant, Whitsfler, B.C., British
     Columbia, Canada, July, 1994.
Gilmour, C.C.,  and E.A.  Henry.
     1991. Mercury methylation in
     aquatic systems affected by acid
     deposition. Environ. Poll.
Gilmour, C.C., E.A. Henry, and R.
     Mitchell. 1992. Sulfate stimulation
     of mercury methylation in fresh-
     water sediments. Environ. Sci.
     Technol. 26:2281-2287.
Henry, E.A. 1992. The role of sulfate-
     reducing bacteria in environmental
     mercury methylation. Dissertation,
     Harvard U. 221 pp.
Henry, E.A., L.  J. Dodge-Murphy, G.
     N. Bigham, S.M. Klein, and C. C.
     Gilmour. 1995. Total mercury and
     methylmercury mass balance in an
     alkaline, hypereutrophic urban
     lake (Onodoga Lake, N.Y.) Water
     Air Soil Pollut.  In press.
Oremland, R.S., C.W. Culbertson, and
     M.R. Winfrey. 1991. Methylmer-
     cury decomposition  in sediments
     and bacterial cultures: Involve-
     ment of methanogens and sulfate
     reducers in oxidative
     demethylation.  Appl. Environ.
     Microbiol. 57:130-137.
Ramlal, P.S., C.A. Kelly, J.W.M. Rudd,
     and A. Furutani. 1993. Sites of
     methylmercury production in remote
     Candian Shield Lakes. Can. J. Fish.
     Aquat. Sci. 50:972-979.
St. Louis, V.L., J.M.W. Rudd, C.A. Kelly,
     K.G. Beaty, N.S. Bloom, and RJ.
     Flett. 1994. The importance of
     Wetlands as sources of methylmer-
     cury to boreal forest ecosystems.
     Can. J. Fish. Aquat. Sci. 51:1065-
Watras, C.J., N.S. Bloom, S.A. Claas,
     K.A. Morrison, C.C.  Gilmour, and
     S.R. Craig. 1995. Methylmercury
     production in the anoxic hypolim-
     nion of a dimictic seepage lake.
     Water Air Soil Pollut. In press.

Conference Proceedings
Watras, C.J., and 21 others. 1994. Sources
     and fates of mercury and methylm-
     ercury in Wisconsin Lakes. In C.
     Watras and J. Huckabee, ed.,
     Mercury Pollution: Integration and
     Synthesis, pp. 153-177. Lewis
     Publishers, Boca Raton, FL.
Winfrey, M.R., and J.W.M. Rudd. 1990.
     Environmental factors affecting the
     formation of methylmercury in low
     pH lakes: A review. Environ. Tox.
     Chein, 9: 853-869.
Wiener, J.G., W.F. Fitzgerald, C J.
     Watras, and R.G. Rada. 1990.
     Partitioning and bioavailability of
     mercury in an experimentally
     acidified Wisconsin lake. Environ.
     Tox. Chem. 9: 909-918.


                 National Forum on
                    Mercuiry in Fish
Considerations  in the Analysis of
Water and  Fish for Mercury
Nicolas S. Bloom
Frontier Geosciences Inc., Seattle, Washington
     This presentation will discuss
     methods and relevant analytical
     considerations necessary for the
accurate and precise determination of
total mercury and methylmercury in
aquatic organisms and the waters in
which they live.  The topics that will be
discussed are (1) "ultra-clean" sample
handling; (2) methods and justification
for obtaining uiformation on mercury
speciation; and (3) typical results for
mercury speciation in a wide range of
aquatic organisms.
Ultra-Clean Sample Handling

     Only in the last decade have
researchers been able to accurately
measure mercury in ambient environ-
mental media. Earlier limitations were
caused more by contamination than by
inadequate detection limits. With the
development of ultra-clean sample
handling, the average value and the
variability for the observed concentra-
tion of mercury in surface waters have
decreased dramatically over time
(Bloom, 1995; Fitzgerald and Watras,
1989). The ultra-clean techniques
discussed here were designed for and
apply most specifically to aqueous
samples, where the observed concentra-
tions might be in the 1-10 ng/1 range.
For biota samples, which contain
concentrations 105 to 107 times higher,
these rigorous techniques are not as
necessary (Bloom, 1992).
    Ultra-clean sample collection
begins with processing of equipment in
a low-mercury environment. Particulates
are controlled by passing air through
high-efficiency (HEPA) filters. While
sufficient for all other trace metals, most
mercury is found in the gaseous phase,
thus requiring additional steps. Most
importantly, the level of mercury in the
air must be monitored. If total gaseous
mercury is -under 10 ng/m3, then the lab
is clean for low-level work, whereas if
the lab air has levels greater than 100
ng/m3 mercury, it should be considered
unacceptable. Reductions in gaseous
mercury levels can often be effected by
ventilating the space directly with large
volumes of outside air or by placing
mercury removal filters (gold or carbon)
on the intake to the HEPA filters.  The
cleanroom must also be equipped with a
continuous source of low-mercury
reagent-grade water (< 1 ng/1 mercury).
    Ultra-clean sample handling
mandates that the mercury concentration
of all reagents, gases, water, and room
air be known at all times and that
corrective action be taken if levels
become excessive. Often, reagents can
be used off the shelf or purified to the
point that they contribute less than 10
percent to the total signal obtained from
natural pristine samples. Gases can be
purified by passing them through gold

       National Forum on Mercury in Fish
                      traps prior to use. Some temperature-
                      resistant reagents (e.g., sodium chloride
                      (NaCl)) can be purified by heating to
                      >500 "C, whereas others (e.g., stannous
                      chloride (SnCl2) solution) can be
                      purified by purging with low mercury
                           For water samples, the best
                      materials are hot-acid-cleaned Teflon®,
                      borosilicate glass, or quartz (Bloom,
                      1995). For temporary contact, acid-
                      cleaned hard plastics such as polycar-
                      bonate may be used, but specific items
                      should be tested for mercury contamina-
                      tion prior to use. Soft plastics such as
                      polyethylene and Tygon® should be
                      avoided. These materials allow diffu-
                      sion of gaseous mercury and are diffi-
                      cult to clean. Biota samples are col-
                      lected in polyethylene bags or
                      acid-cleaned glass jars with Teflon®
                           Handling of samples is undertaken
                      with the aim of maintaining a
                      "cleanroom" environment around the
                      samples at all times. In the clean
                      laboratory, this is relatively easy.  The
                      major concern is to handle all containers
                      while wearing cleanroom gloves, and to
                      change gloves whenever they have
                      touched something that is not ultra-
                      clean.  Except when samples are being
                      transferred for analysis, they should be
                      tightly capped to avoid diffusion of
                      mercury into the bottle (Gill and
                      Fitzgerald,  1985).
                          For field collection, a technique
                      called "clean hands-dirty hands" is
                      employed (Bloom, 1985; Fitzgerald and
                      Watras, 1989). The process starts in the
                      cleanroom, where the sample containers
                      are cleaned and double bagged. In the
                      field, the sample container is withdrawn
                      from the box by the person designated
                      "dirty hands," who opens the outer bag
                      only.  "Clean hands," wearing a fresh
                      pair of cleanroom gloves, reaches into
                      the bag carefully, opens the inner bag,
                      and withdraws the bottle. "Clean
                      hands" then opens the bottle, pours the
                      acidified ultra-clean water out of the
                      bottle, rinses the bottle and cap with
                      sample water, and collects the sample.
                      The lid is replaced tightly, and the bottle
is returned to the inner bag. "Clean
hands" reseals the inner bag, and "dirty
hands" reseals the outer bag. The
samples are then returned to the labora-
tory or some other stable, clean area for
     Aqueous samples to be analyzed
for total mercury or methylmercury may
be stored longer than 4 months if
acidified with hydrochloric acid (HC1
(0.5 percent v/v)) and kept in the dark.
Aqueous samples to be analyzed for
methylmercury only, and all biota
samples may be stored frozen indefi-
nitely. Long-term storage should be in
Teflon® bottles, with the caps screwed
on very tightly using a wrench.  Samples
stored in containers with loose lids or
made from polyethylene may gain a
mercury level through diffusion. For
short periods  (days-weeks), aqueous
samples may be stored unpreserved in
Teflon® bottles. This allows better
preservation of the in situ speciation of
the labile chemical and physical mer-
cury speciation.
Analytical Methods for
Mercury Speciation

     Because of the low detection limits
required, most ambient aquatic mercury
measurements are performed using
similar techniques, as was illustrated in
a recent intercomparison exercise
(Bloom et al., 1995). Almost univer-
sally, mercury is detected by one of the
three cold vapor atomic spectroscopic
methods—atomic absorption (AA),
atomic fluorescence (AF), or atomic
emission (AE). Until recently, AA was
by far the method of choice for mercury
determination due to its low detection
limits and simplicity of design. In the
past decade, however, many laboratories
have switched to AF, which offers a
wider linear range and is less prone to
interferences (Bloom and Fitzgerald,
1989). AF also offers an approximate
102 reduction in detection limit, thus
allowing the quantification of individual
mercury species, which in water might
exist in the pg/1 range. Although

 Conference Proceedings
 sensitivity is not a limiting factor in
 tissue analysis, the use of a more
 sensitive detector allows the use of
 smaller samples, thus reducing matrix
      To obtain sufficiently low detec-
 tion limits (<0.1  ng/1) to quantify
 mercury in ambient aqueous samples, a
 large aliquot (50-1000 ml) is processed
 and the mercury content preconcentrated
 prior to injection into the detector. For
 total mercury,  this involves converting
 all mercury present to volatile Hg°, and
 then purging onto an amalgamation trap
 (usually gold) for collection (Fitzgerald
 and Gill, 1979).  The mercury collected
 on the trap is then thermally desorbed
 into the analytical system as a single,
 sharp pulse. Most laboratories now use
 the method of bromine chloride (BrCl)
 preoxidation (to break down organomer-
 curials), followed by SnCL, reduction to
 release the mercury (Bloom and Cre-
 celius, 1983). Equally effective are
 other preoxidation steps bromine (Br2),
 potassium permanganate/potassium
 chloride (KMnO4/KCl), potassium
 (KjCrO/K^Og,  or ultraviolet (UV)
 photo oxidation), or a one-step reduc-
 tion, using sodium borohydride
 (NaBH4) (GUI and Bruland, 1990).
 These methods, when used with either
 AA (200- to 1000-ml samples) or AF
 (20- to 100-ml  samples), have detection
 limits that are ultimately determined by
 the variability in the reagent blank,
 rather than instrumental limitations.
 Recently, several  direct-purge (no gold
 pretrapping) methods have been repor-
 ted with detection limits of approxima-
 tely 1 ng/1. These methods, while
 offering the advantage of greater sample
 throughput, have detection limits that
 are too high to accurately quantify
 ambient aqueous mercury concentra-
 tions for research  purposes.
     Most ambient aqueous methylmer-
 cury determinations are made using
 aqueous phase ethylation and GC
 separation, after a pre-extraction step to
 separate the methylmercury from the
natural matrix.  The most common
method involves partitioning into
 dichloromethane (CH2C12) and then
 back into water (Bloom, 1989), but
 now, due to its greater simplicity,
 accuracy, and reduction of hazardous
 chemicals, distillation is becoming
 favored (Horvat et al., 1993).  To
 quantify methylmercury in the ambient
 concentration (0.01-1 ng/1) range, the
 use of an AF detector is required. The
 use of sulfhydryl-impregnated cotton
 extraction, followed by traditional
 GC/ECD detection of methylmercury as
 the chloride, has been documented (Lee
 and Mowrer, 1989),  but the method
 requires considerably larger sample
 volumes and longer processing times
 and is prone to positive interferences.
      Because detection limits are not
 critical in the case of biota, more
 options are available for analysis. The
 most commonly used technique is a
 selective digestion method that allows
 the determination of total mercury and
 inorganic mercury Hg(II) directly, and
 methylmercury by difference (Magos,
 1971).  In this method, the sample is
 digested in.a strong alkaline solution,
 and Hg(II) is determined by SnCl2
 reduction and atomic spectroscopic
 detection. If cadmium (Cd) is added
 during the reduction, the methylmercury
 is reduced as well. Alternately, a two-
 digestion procedure may be used, in
 which total mercury is determined on a
 nitric acid/hydrogen sulfate (HNO3/
 H2SO4)  digested aliquot (Bloom, 1989),
 and Hg(II) determined as above. Meth-
 ylmercury is determined by difference.
 This method, although it intercompares
 well with more chemically specific
 methods, is operationally defined, and
 the results are thus always clouded by
     The most common technique used
 to specifically determine methylmercury
 in tissues involves extraction into an
 organic  solvent and then quantification
 of the chloride by GC/ECD (Westoo,
 1967). This technique is sensitive and
 allows the identification of other niono-
 alkyl species, but it risks positive
interferences from other halogen-con-
taining compounds. If methylmercury is
determined using this technique, then an

      National Forum on Mercury in Fish
                      additional digestion for total mercury or
                      Hg(H) is required. Recently, a method
                      was developed that allows the positive,
                      simultaneous determination of both
                      methylmercury and Hg(II) on the same
                      digest, using aqueous phase ethylation/
                      GC separation and CVAFS detection
                      (Bloom, 1989).  This method also
                      affords the simultaneous determination
                      of dimethyl mercury, if present.  The
                      sample is digested in a mixture of
                      potassium hydroxide (KOH) and
                      methanol, and then a small aliquot is
                      ethylated to obtain volatile ethyl analogs
                      of the compounds present.  The species
                      are eluted in the order of dimethyl
                      mercury, methyl ethyl mercury (meth-
                      ylmercury analog), and diethyl mercury
                      (Hg(H) analog). The technique has a
                      detection limit of approximately 0.5
                      ng/g, and is not prone to matrix inter-
                       Occurrence of Mercury
                       Species In Water and Biota

                            In most aquatic environments,
                       total mercury ranges in concentration
                       from approximately 0.5 to 5 ng/1, while
                       the fish living in those waters might
                       contain from 100 to 2,000 ng/g. The
                       methylmercury content of natural waters
                       is generally about 5-20 percent of the
                       total (Bloom et al., 1991), whereas in
                       free-swimming fish, it is approximately
                       95-100 percent of the total (Bloom,
                       1992). The methylrnercury content of
                       natural surface waters is positively
                       correlated with dissolved organic carbon
                       (DOC) content (Bloom et al., 1991).
                       Clear lake water and sea water contain
                       total mercury of approximately 0.2 to 1
                       ng/1 and methylmercury of <0.01 to 0.05
                       ng/1. Brown-colored lake waters often
                       have total mercury of approximately 2 to
                       5 ng/1, and corresponding methylrnercury
                       levels of 0.2 to 0.5 ng/1, while darkly
                       stained bogs may contain total mercury
                       >10 ng/1 and methylmercury >2 ng/1.
                       Most contaminated sites have surprisingly
                       low aqueous mercury concentrations (5 to
                       50 ng/1 total mercury, 0.2 to 5 ng/1
                       methylmercury) due to high particle and
biotic reactivity. Although these concen-
trations appear low given high levels of
localized mercury input, they are suffi-
cient to result in dangerously high meth-
ylmercury levels in fish (i.e., 1,000-
10,000 ng/g).
     Recent analyses carried out under
strictly controlled ultra-clean conditions
have indicated that virtually all (>95
percent) of the mercury in the muscle
tissue of free-swimming fish is in the
form of methylmercury (Lasorsa and
Alan-Gil, 1995; Bloom, 1992).  Earlier
reports of 10-30 percent inorganic mer-
cury may be biased by low-level Hg(H)
contamination and/or analytical proce-
dures that measure total mercury and
methylmercury or ionic mercury in a
separate analysis, with the remaining
species being determined by difference.
For whole fish, >90 percent is found to be
methylmercury although a general
dilution occurs due to lower mercury
levels in bone and skin. Some organs,
such as the liver, do contain higher levels
of Hg(II) but do not contribute signifi-
cantly to the overall body burden.  For
aquatic organisms other than fish, the
mercury speciation varies significantly.
Generally, species such as crabs and
shrimp contain high fractions of methylm-
ercury (70-100 percent), whereas shellfish
such as mussels and clams often contain a
majority of their mercury burden (50-90
percent) as Hg(IT).

Bloom, N.S. 1989. Can. J. Fish. Aquat.
     Sci. 46: 1131.
	. 1992. Can. J. Fish. Aquat. Sci.
     49: 1010.
       -. 1995. Environ Lab. In press.
Bloom, N.S., and E.A. Crecelius. 1983.
     Mar. Chem. 14: 49.
Bloom, N.S., and W.F. Fitzgerald. 1988.
     Anal. Chim. Acta 209: 151.
Bloom, N.S., M. Horvat, and CJ.
     Watras. 1995. Water Air Soil
     Pollut. In press.
Bloom, N.S., CJ. Watras, and J.P.
     Hurley. 1991. Water Air Soil
     Pollut. 56: 477.

Conference Proceedings
Fitzgerald, W.F., and G.A. Gill. 1979.
     Anal. Chem. 55: 453.
Fitzgerald, W.F., and C.J. Watras. 1989.
     ScL Tot. Environ. 87/88: 223.
Gill, G.A., and K.W.  Bruland. 1990.
     Env. Sci. Technol. 24: 1392.
Gill, G.A., and W.F. Fitzgerald. 1985.
     Deep Sea Res. 32: 287.
Horvat, M. 1993. Anal. Own. Acta 282:153.
Lasorsa, B., and S. Allen-Gil. 1995.
     Wat. Air Soil Pollut. In press.
Lee, Y.-H., and J. Mowrer. 1989. Anal.
     Chim. Acta 221:259.
Magos, L. 1971. Analyst 96: 847.
West66, G. 1967. Acta Chem. Scand.
     21: 1790.

                                                        National Forum on Mercury in Fish
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                      National Forum on Mercury in Fish
                                   Chromatogram Output from Ethylation/
                                        GC/CVAFS Speciation System
                                                  (Bloom, 1989)
                         5 600
                                                5              10
                                                 Retention Timo. min
                                  Stability  of Total  Hg in  Water


 time, d
                                                                  EPA storage
                                                                  time limit

                                  n     teflon, unpreserved

                                  O     teflon + 0.05 N Acid

                               	O—-   polyethylene + 0.05 N Acid

Conference Proceedings
             Analytical Detection Limits for Hg Speciation
             (typical level)
         Au amalgamation/AS
              Direct AAS
              Direct AFS
                                  water (ng/L)
  biota (ng/g)
total     methyl

                         Schematic of Ethyla»ion/GC/CVAFS
                             System for Hg Spedatum
                                   (Bloom, 19B9)

                                                             National Forum on Mercury in Fish
                          Observed Total Hg in Surface Waters 1970 -1990
                                         (Bloom, 1995)
                                            Julian year
                          Analytical Method Requirements

                     > Sensitive

                                          Water        Fish
                             Total Hg    0.1 ng/L     0.01 ng/g
                            Methyl Hg   0.01 ng/L    0.01 ng/g

                     > Accurate (±10%)

                     > Precise  (±10%)

                     > Generalizable (Water, Sediment, Tissue)

                     > Chemically Specif ic (Hg(II), MMHg, DMHg)

                     > Interference Free

                     > Non-Contaminating

                     > Economical

                   National Forum on
                      Mercury in Fish
 Bioaccumulation  of  Mercury
 in  Fish
 James G. Wiener
 National Biological Service, Upper Mississippi Science Osnter, La Crosse, Wisconsin
     This presentation reviews the state
      of our knowledge of the uptake,
      tissue distribution, and bioac-
 cumulation of methylmercury in fresh-
 water fish. Environmental conditions or
 situations associated with high mercury
 (Hg) levels in fish are discussed, and the
 range of concentrations in piscivorous
 fishes under such conditions is de-
 scribed. The  toxicological significance
 of methylmercury to fish is also exam-
Exposure to Waterborne

     In the past decade, the application
of clean techniques for sampling and
handling surface water, wet deposition,
and air, in conjunction with new meth- •
ods for the direct measurement of
methylmercury, have greatly advanced
our understanding of the biogeochemis-
try of mercury.  Concentrations of total
mercury (unfiltered samples) range from
0.6 to 4 ng/1 for lightly contaminated
lakes and streams, but might seasonally
be much higher in very humic streams.
In directly contaminated waters, concen-
trations of total mercury vary from
about 5 to  100 ng/1 and are often in the
range of 10-40 ng/1. Methylmercury
concentrations in most oxic surface
waters range from about 0.01 to 0.8 ng
Hg/1. These waterborne concentrations
of mercury are probably much too low
to cause direct toxic effects, either in
 adult fish or in the more sensitive early
 life stages.
 Uptake of Mercury in Fish

     Nearly all (95 to 99 percent) of
 the mercury accumulated in fish is
 methylmercury even though very little
 of the mercury present in freshwater
 ecosystems exists as methylmercury.
 The microbial production of methyl-
 mercury by methylation of inorganic
 Hg(II) in the environment is conse-
 quently a key mechanism affecting
 mercury concentration in fish. Fish do
 not methylate inorganic mercury within
 their tissues although methylation does
 occur within the gut. Fish obtain
 methylmercury from their diet and
 from water passed over the gills.
 Inorganic mercury is absorbed much
 less efficiently across the gut and gills
 and is eliminated more rapidly than is
     The diet is the primary route of
 methylmercury uptake by fish inhabit-
 ing natural waters, probably contribut-
 ing more than 90 percent of the meth-
 ylmercury accumulated. The
 assimilation efficiency for uptake of
 dietary methylmercury in fish is
probably 65 to 80 percent or greater,
 whereas about 10 percent of the
methylmercury passing over the gills is
assimilated. In temperate waters, the
accumulation of mercury by fish seems
to be most rapid in summer, when the

                                                                     National Forum on Mercury in Fish
                      feeding and metabolic rates of fish and
                      the microbial production of methylmer-
                      cury are greatest. In the laboratory, fish
                      readily accumulate high concentrations
                      of methylmercury from water when
                      exposed to methylmercury concentra-
                      tions several orders of magnitude greater
                      than those in natural waters.
                      Tissue Distribution and

                           Methylmercury rapidly penetrates
                      and is cleared from the gut and the
                      gills, binds to red blood cells, and is
                      rapidly transported to all internal
                      organs, including the brain. The route
                      of uptake (gut vs. gill) has little influ-
                      ence on the distribution of methylmer-
                      cury among most internal organs and
                      tissues, except that concentrations in
                      the gills are much higher after
                      waterborne exposure (than dietary)  and
                      concentrations in the intestines are
                      higher after dietary exposure.  Concen-
                      trations of methylmercury are typically
                      greatest in the blood, spleen, kidney,
                      and liver in both laboratory tests and
                      field studies.
                           There is a dynamic internal
                      redistribution of assimilated methylmer-
                      cury among the tissues and organs of
                      fish exposed to methylmercury in
                      laboratory and field studies. The
                      concentrations and burdens (masses) in
                      the blood, spleen, kidney, liver, and
                      brain decrease after exposure to either
                      waterborne or dietary methylmercury
                      ceases, and skeletal muscle is the
                      primary "receiver" of the redistributed
                      methylmercury. Most of the methyl-
                      mercury in the body eventually accumu-
                      lates in muscle, bound to sulphydryl
                      groups in protein, even though concen-
                      trations are usually less  in muscle than
                      in other tissues.
                            Fish do not readily eliminate
                      methylmercury. Estimated half-reten-
                      tion times of methylmercury in freshwa-
                      ter fish typically range from about 0.5 to
                      2 years. In some studies, there has been
                      no measurable excretion of methylmer-
                      cury from fish.
Effects of Diet, Food-Web
Structure, and Longevity

     High concentrations of mercury
are sometimes observed in fish from
waters that lack direct sources of
mercury or conditions, such as low pH,
known to enhance the methylation or
bioavailability of the metal. In particu-
lar, mercury concentrations sometimes
exceed 0.5 or 1.0 ug/g wet weight
(values widely used as criteria in fish
consumption advisories) in the axial
muscle of long-lived, piscivorous fish.
This situation is partly due to the
influence of diet, food-web structure,
and longevity on the bioaccumulation
and concentration of mercury in fish.
     Feeding habits and food-chain
structure influence methylmercury
uptake in fish, and piscivorous fishes
usually contain higher concentrations
than coexisting fishes of lower trophic
levels. Methylmercury biomagnifies in
aquatic food chains.  In addition, the
fraction of total mercury that exists as
methylmercury in aquatic organisms
increases progressively from primary
producers to fish.
     The structure of aquatic food webs
can influence mercury concentrations in
fish, particularly in species that are
typically piscivorous. For example,
lake trout Salvelinus namaycush and
northern pike Esox lucius have higher
mercury concentrations when forage
fish, such as rainbow smelt Osmerus
mordax or perch (Perca sp.), are
present. Concentrations in northern pike
in a Finnish lake lacking forage fish
were about one-fourth those in northern
pike in similar, nearby  lakes with forage
     Mercury concentrations in a fish
species within a given water body
generally increase with increasing age or
body size, partly because the rate of
uptake greatly exceeds the rate of
elimination. In addition, the methyl-
mercury content of the diet of some
fishes, particularly those which are
partly or totally piscivorous as adults,
increases as the fish grows larger. In
lake trout, for example, the rate of

 Conference Proceedings
 mercury accumulation increases greatly
 when the fish become large enough to
 switch from a diet of invertebrates to
 forage fish.

 Effect of Lake Size

      Lake size and temperature affect
 the bioaccumulation of mercury in
 fish.  In northwestern Ontario, the
 mean concentrations in axial muscle
 of walleyes Stizostedion vitreum and
 northern pike ranged about 0.7-1.1
 jig/g wet weight in small (89-706
 hectare) lakes but were less than 0.4
 ug/g hi nearby, larger (2,219-34,690
 hectare) and colder lakes. Specific
 rates  of mercury methylation in the
 lakes were positively correlated with
 water temperature, whereas specific
 rates  of methylmercury demethylation
 (by microbes) were negatively
 correlated with temperature.  Scien-
 tists attributed the differing mercury
 concentrations in fish among the lakes
 to temperature-related variation in
 the microbial production of methyl-
 Point-Source Pollution

      Many surface waters have been
 contaminated by direct discharges of
 mercury from point sources, including
 chloralkali plants, pulp and paper mills,
 and certain other industrial facilities.
 Concentrations in axial muscle in
 individual piscivorous fishes taken from
 these contaminated waters were often in
 the range of 1-10 ug/g wet weight, with
 mean concentrations in piscivorous
 species often hi the range of 1-7 pg/g
 wet weight. High concentrations of
 methylmercury (1-2.5 ug/g wet weight)
 have also been observed in omnivorous
 fishes from such waters.
     Point-source discharges of mercury
 to surface waters have declined in many
 industrialized countries since the  1960s
 and 1970s. Such reductions were
 generally followed by decreased mer-
 cury concentrations in aquatic biota. In
 some waters, however, concentrations in
 fish continued to exceed 0.5 or 1.0 ug/g
 wet weight for several years after
 mercury inputs were reduced or after
 industrial-source plants were inacti-
Elevated Mercury
Concentrations in Fish

     Many conditions can lead to the
bioaccumulation of high concentrations
of methylmercury in fish, including
anthropogenic discharges of mercury to
surface waters, flooding of new im-
poundments, and atmospheric deposi-
tion of mercury to low-pH and humic
waters.  The most contaminated
piscivorous fish, with maximum
concentrations in axial muscle of about
5-15 ug/g wet weight, have been
associated with point-source discharg-
ers, such as chloralkali plants. Piscivo-
rous fish from newly flooded impound-
ments have maximum concentrations in
muscle of 3-4 ug/g wet weight or
greater. In piscivores from low-pH or
humic lakes, axial muscle generally
contains from 0.5 to 2 ug Hg/g wet
Gold Atoning

     Gold-mining operations that used
the mercury amalgamation process have
caused long-term contamination of
sediment and fish in certain rivers.
Recent gold-mining activities have
caused substantial mercury pollution in
the Madeira River in the Amazon River
basin of South America. Mercury
concentrations in axial muscle of fish
from contaminated sites in the Madiera
River frequently exceeded 1.0 ug/g wet
Atmospheric Deposition to Low-pH
and Humic Lakes

     Piscivorous fish in waters with low
acid neutralizing capacity (<60 ueq/1),
low pH (<6.7), or high humic content
often contain mercury concentrations in
axial muscle in the range of 0.5-2.0 ug/g
wet weight, even in waters far from

      National Forum on Mercury in Fish
                      anthropogenic sources of the metal.
                      This is a geographically widespread
                      pattern, observed in largemouth bass
                      Micropterus salmoides, smallmouth
                      bass M. dolomieui, walleye, and north-
                      ern pike. This pattern is also evident in
                      forage fishes, such as yellow perch
                      Percaflavescens.  The greater accumu-
                      lation of methylmercury in fish in low-
                      pH waters has been attributed in part to
                      greater in-lake microbial production of
                      methylmercury. In regions of Sweden,
                      Finland, Canada, and the United States
                      that have many low-alkalinity  and
                      humic waters, much of the mercury in
                      fish in remote or semi-remote lakes
                      seems to be derived from atmospheric

                      Newty flooded Reservoirs

                           In newly flooded temperate and
                      subarctic reservoirs, concentrations in
                      axial muscle of piscivorous fishes often
                      average 0.6 to 3.0 ug/g wet weight;
                      maximum concentrations of 2-6 ug/g
                      can, in some cases, equal or exceed
                      concentrations in fishes from  waters
                      heavily contaminated by direct
                      industrial discharges.  For comparison,
                      mean concentrations in northern pike
                      and walleyes were typically in the
                      range of 0.20-0.35 ug/g in existing
                      surface waters before flooding by the
                      Churchill River diversion in northern
                      Manitoba, Canada. Nine years after
                      creation of the La Grande 2 reservoir
                      (part of the La Grande hydroelectric
                      complex) in the Canadian province of
                      Quebec, standardized concentrations of
                      mercury were 3.0 ug/g wet weight in
                      70-cm northern pike and 2.8 ug/g in
                      40-cm walleye; concentrations were
                      even higher (3.5 ug/g in 70-cm
                      northern pike) farther downstream, in
                      an unimpounded  section of the La
                      Grande River. In comparison, concen-
                      trations in fish from 29  reference lakes
                      near the La Grande complex were 0.6
                      ug/g wet weight in 70-cm northern pike
                      and 0.7 ug/g in 40-cm walleye.
                           The rapid increase in bioaccumula-
                      tion of mercury after flooding is due to
                      the enhanced microbial methylation of
inorganic mercury present in the inun-
dated terrestrial habitats. In subarctic
reservoirs, the magnitude of the increase
in fish-mercury concentration after
flooding is positively related to the ratio
of newly flooded area to preimpound-
ment lake area. Mercury concentrations
in fish might remain elevated for
decades after flooding.
lexicological Implications for

     Methylmercury exerts its most
harmful effects on the central nervous
system, even though other effects have
been observed in laboratory studies.  In
the laboratory, long-term dietary expo-
sure to methylmercury has caused
inability to feed, incoordination, re-
duced responsiveness, and starvation.
These symptoms were also observed at
grossly polluted Minamata Bay, Japan,
where severely poisoned adult fish had
concentrations of 8 to 24 ug/g wet
weight in axial muscle.
     Fish possess mechanisms to
protect against inorganic mercury, but
seem to have fewer defenses against
methylmercury. Methylmercury crosses
biological barriers (gills, intestines, and
internal cellular membranes) much more
readily than inorganic Hg(II) species.
Unlike inorganic mercury, methylmer-
cury in fish is neither effectively ex-
creted nor bound to metallothioneins.
Storage in the muscle, which seems to
be less sensitive to methylmercury than
other tissues and organs, may serve as
the primary detoxification mechanism
for methylmercury in fish. The binding
of assimilated methylmercury to pro-
teins in the skeletal muscle, even if
incidental, clearly reduces the exposure
of the brain to methylmercury.
     The rate of accumulation in fish
seems to affect the toxicity of methyl-
mercury. If it is accumulated slowly,
fish can tolerate higher tissue concentra-
tions of mercury, presumably due to  the
internal transfer and binding of methyl-
mercury to proteins in skeletal muscle
(the primary storage site), which de-

Conference Proceedings
creases exposure of the central nervous
     The developing fish embryo can be
severely  affected by a small quantity of
methylmercury or inorganic mercury.
Methylmercury derived from the adult
female, however, probably poses greater
risk than waterborne mercury for
embryos in natural waters, even though
the amount of mercury transferred to the
eggs during oogenesis is small.  In
laboratory bioassays, maternally derived
mercury  (both inorganic and methyl)
can adversely affect the survival,
hatching, and development of embryos.
The mercury content of eggs reflects the
maternal exposure history, with the
concentration in the egg increasing
concomitantly with parental exposure
and tissue concentrations.
     The primary toxicological effect of
mercury  on fish populations—if any, at
observed exposure levels—would
probably be reduced reproductive
success resulting from toxicity of
maternally derived mercury to embry-
onic and larval stages.  Sublethal and
lethal effects on fish embryos are
associated with mercury residues in
eggs that are much lower than—perhaps
1 percent to 10 percent of—the residues
associated with toxicity hi adult fish. In
rainbow trout Oncorhynchus mykiss, for
example, mortality of embryos coin-
cided with total mercury concentrations
of 0.07-0.10 ug/g wet weight in the egg,
values less than 1 percent of the tissue
residues (10-30 ug/g) associated with
toxicity in the adult.  Furthermore, some
data imply that for some fish popula-
tions, the margin of safety between
harmful and existing mercury residue
levels might be much less for embryo-
larval stages than for adults.

Bloom, N.S.  1992.  On the chemical
     form of mercury in edible fish and
     marine invertebrate tissue. Can. J.
     Fish. Aquat. Sci. 49:1010-1017.
Bodaly, R.A., J.W.M. Rudd, R.J.P.
     Fudge, and C.A. Kelly. 1993.
     Mercury concentrations in fish
     related to size of remote Canadian
     Shield lakes.  Can. J. Fish. Aquat.
     Sci. 50:980-987.
Boudou, A., and F. Ribeyre. 1985.
     Experimental study of trophic
     contamination of Salmo gairdneri
     by two mercury compounds—
     HgCl2 and CH3HgCl—analysis at
     the organism and organ levels.
     Cope. Water Air Soil Pollut.
Effler, S.W.  1987. The impact of a
     chlor-alkali plant on Onondaga
     Lake and adjoining systems.
     Water Air Soil Pollut. 33:85-115.
Francesconi, K.A., and R.C.J. Lenanton.
     1992. Mercury  contamination in a
     semi-enclosed marine embayment:
     organic and inorganic mercury
     content of biota, and factors
     influencing mercury levels in fish.
     Mar. Environ. Res. 33:189-212.
Putter, M.N.  1994. Pelagic food web
     structure influences probability of
     mercury contamination in lake
     trout (Salvelinus namaycush). Sci.
     Total Environ. 145:7-12.
Grieb, T.M., C.T. Driscoll, S.P. Gloss,
     C.L. Schofield, G.L. Bowie, and
     D.B. Porcella. 1990. Factors
     affecting mercury accumulation in
     fish in the upper Michigan penin-
     sula. Environ. Toxicol. Chem.
Harrison, S.E., J.F. Klaverkamp, and
     R.H. Hesslein. 1990. Fates of
     metal radiotracers added to a
     whole lake: accumulation in
     fathead minnow (Pimephales
     promelas) and lake trout
     (Salvelinus namaycush).  Water
     Air Soil Pollut. 52:277-293.
Hecky, R.E., DJ. Ramsey, R.A.
     Bodaly, and N.E. Strange. 1991.
     Increased methylmercury contami-
     nation in fish in  newly formed
     freshwater reservoirs. In T. Suzuki
     et al., eds., Advances in Mercury
     Toxicology. Plenum Press, New
     York, pp. 33-52.
Huckabee, J.W., J.W. Elwood, and S.G.
     Hildebrand. 1979.  Accumulation
     of mercury in freshwater biota. In

      National Forum on Mercury in Fish
                           J.O. Nriagu, ed., Biogeochemistry
                           of Mercury in the Environment.
                           Elsevier/North-Holland Biomed-
                           ical Press, New York, pp. 277-
                      Lange, T.R., H.E. Royals, and L.L.
                           Connor. 1993. Influence of water
                           chemistry on mercury concentra-
                           tion in largemouth bass from
                           Florida lakes. Trans. Am. Fish.
                           Soc. 122:74-84.
                      MacCrimmon, H.R., C.D. Wren, and
                           B.L. Gots. 1983. Mercury uptake
                           by lake trout, Salvelinus
                           namaycush, relative to age,
                           growth, and diet in Tadenac Lake
                           with comparative data from other
                           Precambrian Shield lakes.  Can.  J.
                           Fish. Aquat. Sci. 40:114-120.
                      Mathers, R.A., and P.H. Johansen.
                           1985. The effects of feeding ecol-
                           ogy on mercury accumulation in
                           walleye (Stizostedion vitreum) and
                           pike (Esox Indus') in Lake Simcoe.
                           Can. J. Zool.  62:2006-2012.
                      McKim, J.M., G.F. Olson, G.W.
                           Holcombe, and E.P. Hunt.  1976.
                           Long-term effects of
                           methylmercuric chloride on three
                           generations of brook trout
                           (Salvelinus fontinalisy. Toxicity,
                           accumulation, distribution, and
                           elimination. /. Fish. Res. Board
                           Can. 33:2726-2739.
                      Miskimmin, B.M., J.W.M. Rudd, and
                           C.A. Kelly. 1992. Influence of
                           dissolved organic carbon, pH, and
                           microbial respiration rates on
                           mercury methylation and
                           demethylation in lake water. Can.
                           J. Fish. Aquat. Sci. 49:17-22.
                      Phillips, G.R., and D.R. Buhler.  1978.
                           The relative contributions of
                           methylmercury from food or water
                           to rainbow trout (Salmo gairdneri)
                           in a controlled laboratory environ-
                           ment. Trans. Am. Fish. Soc.
                      Phillips, G.R., T.E. Lenhart, and R.W.
                           Gregory.  1980.  Relation between
                           trophic position and mercury
                           accumulation among fishes from
                           the Tongue River Reservoir,
                           Montana. Environ. Res.  22:73-80.
Rask, M., and T.-R. Metsala.  1991.
     Mercury concentrations in north-
     em pike, Esox lucius L., in small
     lakes of Evo area, southern
     Finland.  Water Air Soil Pollut.
Ribeyre, F., and A. Boudou. 1984.
     Bioaccumulation et repartition
     tissulaire du mercure—HgQ2 et
     CH3HgCl—chez Salmo gairdneri
     apres contamination par voie
     directe.  Water Air Soil Pollut.
     23:169-186.   ,
Rodgers, D.W. In press.  You are what
     you eat and a little bit more:
     bioenergetic-based models of
     methylmercury accumulation in
     fish revisited. In C. J. Watras and
     J. W. Huckabee, eds., Mercury
     Pollution: Integration and Synthe-
     sis. Lewis Publishers,  Boca
     Raton, FL.
Rudd, J.W.M., M.A. Turner, A.
     Furutani, A.L. Swick, and B.E.
     Townsend.  1983. TheEnglish-
     Wabigoon River system:  I.  A
     synthesis of recent research with  a
     view towards mercury ameliora-
     tion. Can. J. Fish. Aquat. Sci.
Spry, D.J., and J.G. Wiener. 1991.
     Metal bioavailability and toxicity
     to fish in low-alkalinity lakes:  a
     critical review. Environ.  Pollut.
St. Louis, V.L., J.W.M. Rudd, C.A.
     Kelly, K.G. Beaty, N.S. Bloom,
     and RJ. Flett. 1994. Importance
     of wetlands as sources of methyl
     mercury to boreal forest ecosys-
     tems. Can. J. Fish. Aquat. Sci.
Verdon, R., D. Brouard, C. Demers, R.
     Lalumiere, M. Laperle, and R.
     Schetagne.  1991. Mercury evolu-
     tion (1978-1988)  in fishes of the
     La Grande hydroelectric complex,
     Quebec, Canada.  Water Air Soil
     Pollut. 56:405-417.
Watras, C.J., and N.S. Bloom.  1992.
     Mercury and methylmercury in
     individual zooplankton: implica-
     tions for bioaccumulation.
     Limnol. Oceanogr. 37:1313-1318.

Conference Proceedings
Wiener, J.G., and D.J. Spry.  In press.
     Toxicological significance of
     mercury in freshwater fish.  In G.
     Heinz and N. Beyer, eds.,
Interpreting Environmental
Contaminants in Animal Tissues.
Lewis Publishers, Boca Raton,

               National Forum on Mercury in Fish
    Elevated Hg Levels in Game Fishes

                  Concentration (pg/g wet wt.)
 Source or
    Range in
  Range in
 Chlor-alkali plant
      1 -5
 Newly flooded reservoirs 0.7 - 3
    2- 15
 Low-alkalinity lakes
      0.5 - 0.9
   Source: Wiener & Spry 1995 (data for northern
    walleye, largemouth & smallmouth bass)
     Mercury Concentrations in
     Intoxicated Rainbow Trout
  Life stage     Tissue
                Hg cone.
               (yg/g wet wt.)
 Juvenile &
whole fish
0.07 - 0.10

Conference Proceedings
  Mercury in Northern Pike Finnish Lakes
             (Rask & Metsala 1991)


                           No forage fish
       0   10  20  30  40   50   60  70  80
             Total length of pike, cm

  Environmental Factors Linked  to
	High [Hg] in Fish	

•Point-source discharges of Hg

% Atmospheric deposition of Hg

• Low-alkalinity or hurnic waters

% Enhanced microbial production of  MeHg
     Newly flooded reservoirs
     Low-pH waters, acidified waters
     Wetland ecosystems

                             National Forum on Mercury in Fish
        Biomagnification of MeHg
               marine bay1
                             N. Wisconsin
Piscivorous fish
Forage fish
  1 Francesconi & Lenanton 1992
  2 Watras & Bloom 1992; Wiener et al. 1990
    Mercury in Piscivorous Fishes

  	    and Their Prey	

             Forage   [Hg] ratio
  Piscivore     fish   (predator/prey) Reference
Lake Trout  rainbow

Walleye    y. perch
          etal. 1983

          Cope et al.
           y. perch
Suns et al

Conference Proceedings
  Mercury in Oxic Fresh Waters
 Mercury fraction
 Total Hg (unfiltered water)

  Lightly contaminated

  Direct Hg sources
Cone, range
  (ng Hg/L)
 Methyl Hg
    0.6 - 4

 (often 10-40)

  0.01 - 0.8
  (max. 2.0)
Intrinsic Factors Linked to High
	   [Hg] in Fish
• Diet and trophic position

• Biomagnification in food chains

• Longevity (increased [Hg] with age)


                    National Forum on
                                 Mercury in Fish
  Mercury in  Wildlife
  Charles F. Facemire
  Senior Environmental Contaminants Specialist, Southeast Region, U.S. Rsh and
  Wildlife Service, Atlanta, Georgia
      Elevated concentrations of mercury
      (Hg) have been found in virtually
      all wildlife species.  Although
 each species tends to handle mercury
 body burdens somewhat differently,
 some generalities have been observed.
 Figure 1 presents  a simplified model of
 mercury dynamics in birds and mam-
 mals. Unlike fish and amphibians,
 which may accumulate mercury directly
 from their environment, mercury
 accumulation in avian and mammalian
 species is almost always via ingestion of
 contaminated food.
 Factors Influencing
     As illustrated by
 Figures 2 and 3, total mer-
 cury body burden is gener-
 ally dependent on the type of
 food ingested. (We are what
 we eat.) Lowest concentra-
 tions are usually found in
 herbivores. As the diet
 shifts toward the aquatic
 food chain, concentrations in
 body tissues increase.
 Consequently, maximum
 concentrations generally
 occur in top predators within
 the aquatic food chain. This
 select group includes, but is
not limited to, predaceous
            fish, fish-eating birds (including eagles
            and ospreys), raccoons (Procyon lotor),
            otters (Lutra canadensis), mink
            (Mustela visori), and the endangered
            Florida panther (Felis concolor coryf).
            For example, mean mercury concentra-
            tions in liver tissue and feathers from
            great blue herons (Ardea herodius;
            «=4) collected from a contaminated
            area of northeastern Louisiana were
            48.9 (range==20.1-109.6) ppm wet
            weight (ww) and 27.6 (range=22.4-
            33.8) ppm dry weight (dw), respec-
            tively (USFWS, unpub. data). The hair
            and liver from a Florida panther found
            dead in Everglades National Park
            contained concentrations of 130 ppm
Figure 1.  Mercury dynamics in wildlife.

                                                                      National Forum on Mercury in Fish
                                       Minamata, Japan



                              Hg in Feathers (mg/kg)
                                      Northwestern Ontario
                           0  10 20 30 40 50 60
                           Liver Hg Concentration (mg/kg)
                                       Date from Eisler, 1987
           Figure 2. Mercury concentrations in birds from
           contaminated areas.
                    Fur Seal
                   Sled Dog
                   Arctic Fox
                  Polar Bear
                 Woodmouse hi
                   Opossum I
                   Bank Vole I
                       Wolf I
                      Skunk i
                    Red Fox p
              Cottontail Rabbit
                   Roe Deer
             White-tailed Deer
0.5     1.0    1.5    2.0
   Mercury Concentration (mg/kg)
                                                 From Wren, 1986
            Figure 3.  Mercury concentrations in mammals.
                               dw and 110 ppm ww, respectively
                               (Roelke,  1990). Florida panthers are
                               exposed to mercury by eating raccoons
                               (Roelke et al., 1991). Mercury concen-
                               trations in raccoons collected in South
                               Florida range from 1.7 to 95.2 ppm dw
                               in hair and from 1.5 to 39.3 and 0.3 to
                               5.4 ppm ww  in liver and muscle
                               tissues, respectively  (USFWS, unpub.
Tissue Distribution

     In birds, feathers seem to contain
a significant amount of the total body
burden.  Monteiro and Furness (1994)
reported that 93 percent of total mer-
cury in the adult Bonaparte's gull
(Lams Philadelphia) after completion
of molt was in the plumage.  Mercury
is deposited in feathers as they grow,
and the first feathers developed receive
the greatest amount of mercury
(Braune, 1987). This is most evident in
species such as the Bonaparte's gull,
which have a sequential molt of the
primary feathers (Figure 4).  Total
mercury distribution in some avian
species is shown in Figure 5, and it is
evident that there are interspecific
differences as well as differences
associated with age.
      There are few data regarding
mercury contamination in amphibians
 and reptiles, but the data that are avail-
 able show some interesting trends.
 Mercury distribution in the tissues of the
 American alligator (Alligator
 mississippiensis) appears  to vary with
 liver concentrations (Heaton-Jones,
 1993; Figure 6).
      In mammalian species (Figure 7),
 there seems to be little difference in
 distribution regardless of the level of
 contamination.  Concentrations (relative
 to liver concentrations) in tissues of
 raccoon collected at Okefenokee Na-
 tional Wildlife Refuge, Georgia, which
 had moderate mercury loads
 (range=0.45-56.0 ppm dw in hair, 0.09-
 9.9 ppm ww in liver; USFWS, unpub.
 data), were not significantly different
 (a=0.05)fromthosenoted in raccoons

  Conference Proceedings
  fromSanibellsland, Florida, where
  concentrations (range=l .2-8.1 ppmdw
  and 0.21-2.8 ppmw win hair and liver,
  respectively; USFWS, unpub. data) were
  considered to be near background for this
  species. As noted in Figure 7, the distribu-
  tion of mercury in hair and soft tissues of
  the Florida panther was somewhat similar
  to that of raccoons.
       Organic mercury distributions vary
  greatly between and within species.
  Thompson and Furness  (in Monteiro
  and Furness, 1994) reported that the
  relative proportion of organic mercury
  in liver tissue of 12 species of seabirds
  varied from 3 percent to 100 percent,
  and Norheim (in Monteiro and Furness,
  1994) noted that organic mercury
  constituted 20 percent to 100 percent of
  total mercury in the livers of south polar
  skua (Catharacta maccormicki). Or-
  ganic mercury content in Arctic tern
  (Sterna paradisaed) and Bonaparte's
  gull muscle and liver tissues (Figure 8)
  was apparently correlated with the
  amount offish in the species' respective
 diets (Braune,  1987). Virtually 100
 percent of the mercury in feathers is in
 the organic form.
     Few data are available regarding
 the distribution of organic mercury in
 wild, free-ranging mammals. Virtually
 all (99.8 percent) of the mercury in the
 pelage of the Florida panther is organic
 methylmercury. Distribution in hair and
 other tissues of this species is shown in
 Figure 9.
 Depuration and Metabolism

     Bioaccumulation of mercury is a
 simple matter; disposal is generally not
 as easy.  Feathers appear to be the major
 route of excretion in avian species.
 Much of the dietary mercury accumu-
 lated in soft tissues between molts is
 mobilized into growing feathers, with
 the result that soft tissue concentrations
 decrease by more than half in many
 species. Over 60 percent of the total
 annual loss of mercury in the
Bonaparte's gull occurred during the
autumn molt (Monteiro and Furness,
 Figure 4. Mercury concentrations in primaries.
  Great Egret
                      From Monte/ro and Furness, 1994
Figure 5. Mercury distribution in birds.

                                                                      National Forum on Mercury in Fish




                                Everglades National Park Alligators
                       Brain   Uver  Kidney   Muscte  Scales
            Otter WiU Alligators
                       Brain   Uver   Kidney  Muscle  Scales
                                    Farm-raised Alligators
                       Brain    Uver   Kidney  Mujcle   Scales

                                          From HeatoH-Jiwes, 1993
               Figure 6. Mercury distribution in alligators.
                  zs> p  Raccoons, Ofefenofee NWR, GA
                  ! 1.0
                       Brain  Uver  Kidney Muscle  Half   Skin
Raccoons, Sanifie! Island, FL
                       Brain  Uver  Kidney Muscle  Hair   Skin
                           Florida Panther
                       Brain   Uver  Kidney Muscle   Hair   Skin

                                          U.S. FWS, unpublished data
                Figure 7. Mercury distribution in mammals.
1994). Other routes of excretion include
the feather sheaths and feces, the latter
accounting for the loss of about 22
percent of total dietary intake in
black-headed gull (L. ridibundus)
chicks. Evidence seems to indicate
that females may eliminate as  much as
20 percent of their body burden of
mercury by sequestering it in eggs.
As in feathers, the first egg produced
receives the most mercury.  Monteiro
and Furness (1994) reported a de-
crease in egg mercury concentrations
of nearly 40 percent between the
laying of the first and last eggs of
common tern (S. hirundo) and herring
gull (L. argentatus) clutches.  The
half-life of mercury in birds appears
to be in the range of 35-90 days
(Stickel, 1971).
      Mobilizing mercury into eggs
also might be a major route of excre-
tion for alligators.  Heaton-Jones
(pers. comm.) indicated that female
alligators typically have lower body
burdens than males of the species.  It
is evident from the data presented in
Figure 6 that alligators are using
 some, as yet unknown, mechanism to
 prevent excessive mercury buildup in
 soft body tissues. Heaton-Jones
 (1993) thought that scales might be a
 major route of excretion, but  he found
 very low mercury concentrations in
 scales.  Joiris et al. (1991) have
 proposed that marine mammals are
 able to mineralize organic methylmer-
 cury into the relatively nontoxic
 inorganic form, which accumulates in
 the liver of adult animals.  This
 appears  to be what is happening in
 adult alligators.  Other data regarding
 depuration in reptiles and amphibians
 are lacking.
      The half-life of methylmercury
 in mammalian species is extremely
 variable, ranging from about 3.7 days
 in mice to as much as 74 days in man
 (Stickel, 1971).  Charbonneau et al.
 (1974) reported  a 39-day half-life for
 methylmercury chloride in blood of
 the domestic cat. Most mercury loss
 appears to be in the hair, feces, and to
  a lesser extent, urine.

  Conference Proceedings
  Effects of Mercury

       Often, when dealing with
  toxicants, we find that there is a
  threshold level below which there are
  no observable biological effects.
  Methylmercury is among the most
  potent known inhibitors of mitotic cell
  division (Friberg and Vostal, 1972).
  Friberg and Vostal (1972) also noted
  that mercury compounds produce
  chromosomal aberrations, polyploidy,
  and somatic cell mutations. Thus, at
  the cellular level, there is apparently
  no threshold for methylmercury.
      Mortality has been reported in
 birds with total mercury concentrations
 in liver tissue ranging from 17 (red-
 tailed hawk, Buteo jamaicensis) to 752
 ppm dw (grey heron, Ardea cinerea;
 Eisler 1987). Sublethal effects reported
 by Eisler (1987) include adverse effects
 on growth, development, reproduction,
 blood and tissue chemistry, metabo-
 lism, and behavior. Some of these
 effects have been noted at dietary
 concentrations as low as 0.5 ppm dw
 methylmercury (Heinz, 1979). Mer-
 cury concentrations ranging from 5 to
 40 ppm dw in feathers of adult birds
 have been linked to reproductive
 impairment (Eisler, 1987).
     Laboratory studies using several
 species of amphibians have demon-
 strated mortality of 50 percent of the test
 animals at inorganic mercury concentra-
 tions in water ranging from 1.3  to
 107 ug/1 (Birge et al., 1979).  Concen-
 trations of this magnitude are much
 greater than those usually encountered
 under natural conditions. However, one
 should not assume that mercury is not a
 factor in the decline of amphibian
 populations worldwide.
     It is difficult to document cases of
 mercury poisoning in wild populations.
 In most cases, wild animals seek a
 place of shelter and seclusion when ill.
 In addition, decay processes are rela-
tively rapid. Thus, dead or dying
 animals are rarely found. But, in those
few instances when individual animals
are under a surveillance program, as in
                             I    I  Organic

                             ^•i  Inorganic
  Arctic Tern
 Bonaparte's Gutt
                           From Braune, 1987
Figure 8. Methylmercury in birds.

              S	\
                       OS. FWS taif»tVifttddata
   Figure 9. Methylmercury in panther

                                                                  National Forum on Mercury in Fish
                     the case of the Florida panther, dead
                     animals are easily found. In July 1989,
                     an otherwise healthy breeding-age
                     female panther was found dead in
                     Everglades National Park. As previ-
                     ously noted, mercury residues in hair
                     and liver were 130 and 110 ppm, re-
                     spectively (Roelke, 1990). As these
                     concentrations were well within the
                     range of those noted in dead domestic
                     cats during the incident in Minamata,
                     Japan, the cause of death was listed as
                     mercury toxicosis. Wren (1986) docu-
                     ments several cases of mercury
                     toxicosis in wild animals. Liver tissue
                     residues varied from 30 ppm in a fox
                     (Vulpes vulpes), which was observed
                     staggering and running in small circles,
                     to 96 ppm in an otter, which was acting
                     in a similar manner.  Mercury concen-
                     trations in the brains of two domestic
                     cats, which subsisted on a diet of fish
                     entrails, small fish, and wild game
                     meat, were 16.4 and 6.9 ppm at death,
                      also within the range of mercury-
                     poisoned cats in Minamata. The be-
                     havior of both cats was similar: prior
                     to the onset of convulsions, the cats
                     frothed at the mouth, jumped into the
                      air, and ran in circles. Death in most
                      mammals, including humans, appears
                      to occur when mercury concentrations
                      in the brain approach 20 to 30 ppm
                      (Wren, 1986; Stickel, 1971).  However,
                      mink seem to be the mammalian spe-
                      cies most sensitive to methylmercury
                      poisoning. Mink sustained on a diet
                      containing 5.0 ppm methylmercury
                      showed clinical signs of mercury
                      toxicosis within 24 days and died
                      within 30 days (Aulerich et al., 1974).
                           Outward clinical signs of methyl-
                      mercury poisoning, in addition to
                      those already noted, include incoordi-
                      nation, vertigo, anorexia, weight loss,
                      blindness, ataxia, paralysis, convul-
                      sions, and abnormal vocalization
                      (Wren, 1986).  Internally, severe
                      lesions of brain nerve cells normally
                      result from lethal or near-lethal
                      concentrations  (Wren, 1986; Eisler,
                      1987). Wren (1986) noted a few
                      factors, including bioaccumulation of
                      selenium and internal demethylation
of methylmercury to elemental mer-
cury, which may alter the toxicity of
mercury in mammalian species.
Animals as Monitors of
Mercury Contamination

     In 1977, a symposium was
convened at the University of Con-
necticut to determine the potential of
wildlife species as models for the
detection and study of the effects of
environmental contaminants (NAS,
1979). Participants generally agreed
that much could be gained from this
approach. In the Southeast Region,
we have been using the raccoon to
assess risk to top predators such  as the
Florida panther and red wolf (Canis
rufus) and to monitor environmental
trends. I have spoken with several
individuals or groups that are involved
in monitoring mercury concentrations
in fish, particularly largemouth bass
(Micropterus salmoides).  In most
cases, they have stated that there is no
observable trend.  Although analysis
of all our raccoon tissue samples is
not yet complete, some data are
available. As noted in Figure 10,
there has been more than a two-  to
fourfold increase hi mercury concen-
trations in raccoons from southeastern
Georgia and South Florida.

     Mercury continues to be a serious
 threat to fish and wildlife resources, and
 the magnitude and extent of mercury
 impacts to wildlife might never be fully
 elucidated. Although many of the
 sources of mercury contamination have
 been, or are now being, controlled or
 eliminated, it might be several years
 before we see any significant decrease in
 mercury concentrations in tissues of
 wildlife species. In the interim, it will
 be to our advantage to try to minimize
 future risks by eliminating point source
 emissions in addition to cleaning up
 presently contaminated sites.

 Conference Proceedings

 Aulerich, R.J., R.K. Ringer, and J.
      Iwamoto.  1974.  Effects of dietary
      mercury on mink. Arch. Environ.
      Contam. Toxicol. 2:43-51.
 Birge, W.J., J.A. Black, A.G.
      Westerman, and J.E. Hudson.
      1979. The effects of mercury on
      reproduction of fish and amphib-
      ians. In J.O. Nriagu, ed., The
      Biogeochemistry of Mercury in the
      Environment, pp. 629-655.
      Elsevier/North-Holland Biomedi-
      cal Press, Amsterdam.
 Braune, B.M. 1987. Comparison of
      total mercury levels in relation to
      diet and molt for nine species of
      marine birds. Arch. Environ.
      Contam. Toxicol.  16:217-224.
 Charbonneau, S.M., I.C. Munro, E.A.
      Nera, R.F.  Willes, T. Kuiper-
      Goodman,  F. Iverson, C.A.
      Moodie, D.R. Stoltz, F.A.J.
      Armstrong, J.F. Uthe, and H.C.
      Grice. 1974. Subacute toxicity of
      methylmercury in the adult cat.
      Toxicol. Appl. Pharmacol. 27:569-
 Eisler, R.  1987. Mercury hazards to
      fish, wildlife, and invertebrates:
      A synoptic review. U.S. Fish
      Wildl. Serv. Biol. Rep. 85(1.10).
 Friberg, L., and J. Vostal.  1972.
     Mercury in the environment.
     CRC Press, Cleveland, OH. 215
 Heaton-Jones, T.G.  1993. Mercury
     contamination in  the American
     alligator (Alligator missis-
     sippiensis)  in Florida. Report
     submitted to Alligator Manage-
     ment Section, Wildlife Division,
     Florida Game and Fresh Water
     Fish Commission, November 30,
Heinz, G.H. 1979. Methylmercury:
     Reproductive and behavioral
     effects on three generations of
     mallard ducks. /. Wildl. Manage.
Joiris, C.R., L. Holsbeek, J.M.
     Bouquegneau, and M. Bossicart.





Southeast Georgia
                     Liver     Muscle





  South Florida
          Hair       Uver      Muscle
                      m\97l-73—Bigleretal. 1975
                      ffl 1993-94—USFWS, unpuAllsfied data
Figure 10. Mercury concentrations in raccoons.
     1991. Mercury contamination of
     the harbour porpoise (Phocoena
     phocoend) and other cetaceans
     from the North Sea and the
     Kattegat.  Water Air Soil Poilut.
Monteiro, L.R., and R.W. Fumess.  1994.
     Seabirds as monitors of mercuiry in
     the marine environment. Paper
     presented at the 3rd International
     Conference on Mercury as a Global
     Pollutant, Whistler, British Colum-
     bia, July 10-14, 1994.
NAS. 1979. Animals as monitors of
     environmental pollutants. National
     Academy of Sciences, Washington,
     DC. 421pp.

                                                                    National Forum on Mercury in Fish
                      Roelke,M.E. 1990. Florida panther
                           biomedical investigation: Health
                           and reproduction. Final perfor-
                           mance report, Endangered Species
                           Project E-l E-E-6 7506. Florida
                           Game and Fresh Water Fish
                           Commission, Gainesville.
                      Roelke, M.E., D.P. Schultz, C.F.
                           Facemire, S.F. Sundlof, and H.E.
                           Royals. 1991. Mercury contami-
     nation in Florida panthers. Florida
     Game and Fresh Water Fish
     Commission, Gainesville.
Stickel,W.H. 1971. Ecologic effects of
     methylmercury contamination.
     Environ. Res. 4:31-41.
Wren, CD.  1986. A review of metal
     accumulation and toxicity in wild
     mammals. I. Mercury. Environ.
     Res. 40:210-244.

Conference Proceedings
 Hg  Impacts on ¥isfi & Wildlife

         • Reproduction
         • Growth and Development
         • Behavior
         • Blood and Serum Chemistry
         • Motor Coordination
         • Vision
         • Hearing
         • Histology
         • Metabolism


                 National Forum on
  Day One: September 27,  1994
                   Mercury in Fish
 Questions and Discussion:
 Session  One
       After each speaker's presentation,
       an opportunity for questions and
       answers was provided. Time
 was also allotted for a group discussion/
 question-and-answer session.
 Aquatic Biogeochemistry and
 Mercury Cycling Model

 Dr. Donald Porcella, Electric Power
 Research Institute
 Blogeochemical Cycling of
 Mercury; Global and Local

 Dr. William Fitzgerald, University of

 Q: The global cycle suggests that a
 large pan of the cycle is biologically
 mediated.  How much of this global
 cycle is driven by biologically medi-
 ated reactions, and how old are these
 biological reactions?

 Dr. Fitzgerald:
     Most metals are involved in
 biologically mediated reactions.
 These processes have been around for
 a very long time. Organisms in
 general are not specifically trying to
 reduce mercury for a purpose. The
 mercury concentrations in water are too
 low to turn on the "mer" gene, for
 example, in bacteria.

 Q: What about mercury in ocean

Dr. Fitzgerald:
    It is unlikely that open ocean
sediments play much of a role.
 Q: Would the way that third world
 countries use mercury affect your slide?

 Dr. Porcella:
     You would see a blip in my curve.

 Q: What would be the small effect from
 cutting emissions?

 Dr. Porcella:
     After 30-40 years you would see a
 5 percent decrease.

 Q (Deedee Kathman, Aquatic Resources
 Center): You used a water-based food
 web instead ofbenthic. Please com-

 Dr. Porcella:
     In the midst of the second phase of
 model development, we are in the
 process of incorporating a benthic food

 Q: Regarding use of coal combustion,
 why the drop-off?

Dr. Porcella:
     The peaik is caused by mercury use
for precious metal extraction from
Mexico and Central America.

                                                                    National Forum on Mercury in Fish
                      Mercury Methylation in Fresh

                      Dr. Cindy Gilmour, Philadelphia
                      Academy of Natural Science

                      Q (Trey Brown, U.S. EPA, Region 4):
                      Regarding biological disturbance, . .  .
                      does that have an effect on methyl-

                      Dr. Gilmour:
                           I'm not aware of any studies at this

                      Q (Alan Stem, New Jersey Department of
                      Environmental Protection): How much
                      demethylation takes place in sediment?

                      Dr. Gilmour:
                           There is a significant rate of
                      methylmercury degradation going on in

                      Considerations in the Analysis
                      of Water and Fish for Mercury

                      Nicolas Bloom, Frontier Geoscience

                      Q (Jim Wiener, National Biological
                      Survey):  Regarding the possibility of
                      using preserved fish samples as a way to
                      estimate the magnitude of the increase of
                      mercury levels in fish, would it be possible
                      to do methylmercury analysis offish
                      samples as a way of getting around the
                      preservation contamination problem?

                      Mr. Bloom:
                           Possibly, but there is no way to
                      prove that over 100 years mercury is
                      stable at room temperature in a mu-
                      seum. You will have criticism no
                      matter what. We ran across a case
                      where somebody wanted to do bird
                      feathers that were preserved with
                       mercury chloride. When you have a
                       really high inorganic mercury-to-
                       methylmercury ratio, it's hard to quan-
                       tify the methylmercury.

                       Q (Rob Reash, American Electric
                       Power):  You've given the fact that
historical mercury levels have been
biased due to contamination of water
samples.  How long will it take or where
can we start to look at reliable mercury
data to see the trends showing where
mercury levels have been and where
they're going in surface waters?

Mr. Bloom:
     Start in the late  1970s. Even
today, you only have the option to use a
peer review process to identify which
data sets are acceptable. Most data
collected routinely in the country are not

Q: Looking at larger fish, have you
recognized a variance in parts of the body
that may be carrying a body burden of
mercury? Do you have any recommenda-
tions or ideas on where you might take
subsamples of large fish, given the fact
that with ultra-trace capabilities we are
able to analyze less and less tissue, and
try to side-step this bottleneck that the
chemists get into if they have to grind up
the 5-pound fish? Do you have any ideas
where we can begin to look for a
subsampling technique?

Mr. Bloom:
      That depends on the goal of the
project. I advocate taking muscle tissue
samples in the general case, except in the
case where you're doing a trophic study
where you need to have those whole
values as they  go up the food chain. Most
mercury-in-fish numbers that are being
 monitored are  being looked at from the
 standpoint of human consumption
 advisories, as well as the fact that muscle
 tissue is rather homogeneous. (If you take
 10 samples of muscle out of a big fish,
 you will come up with the same number.)

 Q: You didn't present the intercompar-
 ison results. Would you mind summariz-
 ing those?  They were interesting,

 Mr. Bloom:
      We did  an international
 intercomparison on mercury speciation
 in water. A series of water samples were

Conference Proceedings
collected from a well-mixed lake by
pumping sequentially and then the
samples were sent to laboratories around
the world to measure total and methyl-
mercury. The performance among the
labs was very good. I think 23 or so
laboratories returned results.  Of those,
80 percent returned values that were
within 15 percent of the grand mean,
which coincided with the mean estab-
lished at our lab as the reference.

Q (Russell Isaac, Massachusetts Depart-
ment of Environmental Protection): I
am curious about the acids.  The resins
•were the apparent reason for the
chloralkali.  Sodium-hydroxide-gener-
ated material was the reason for the
water problem. Is that true for the

Mr. Bloom:
     I can't say for sure.  My guess is
that these ultrex acids and so forth are
purified using an industrial sub-boiling
distillation procedure. Unless you are
very careful how you apply that proce-
dure,  which works extremely well for
nonvolatile metals, it can actually lead
to introduction of mercury into the
sample because of the large surface area
of acid exposed to the atmosphere.

Q: There has been some concern
expressed, in connection with chlori-
nated organic levels in fish, that some
Asian populations eat certain parts of
fish that other people do not consider
edible. Are those pans higher in
mercury than muscle?
Mr. Bloom:
      I don't know that for sure.  I know
that livers often have a higher mercury
content than muscle, although they don't
make up a very large mass compared to
the muscle. Jim Wiener might be able
to answer that better than I can.

Q: What about polycarbonate bottles?

Mr. Bloom:
      They're probably good. The
problem with leaping out into other
kinds of bottles is that doing the ad-
equate storage tests at low concentra-
tions is very expensive. You're prob-
ably better off sticking with something
that you know works, rather than trying
to verify quantitatively that some other
container works. We use polycarbonate
bottles in our lab and anecdotally they
seem to work fine.

Group Discussion/Question-
and'Answer Session

Q (Pam Shubat, Minnesota Department
of Health):  I was interested in the
seasonal variation in the mercury levels
in fish that you showed in your models.
What was the magnitude of that varia-
tion, and was it temperature-dependent,
light-penetration-dependent, or what?
Northern lakes,  southern lakes,  ocean?

Dr. Porcella:
     In the model the fish are treated as
a "compartment," so all the mercury is
going into that compartment.  The
amount of methylmercury produced
during the year changes with season.
During low temperature parts of the
year, there is not much production of
methylmercury, as I understand it.  The
other variable is that the amount of fish
in the compartment also changes
seasonally.  There are two things going
on at the same time, and that accounts
for the seasonal variation within the
year.  Based on the model results, it
amounts to roughly 10-15 percent
variation over the year. Results were
from northern lakes. I would expect to
see it smoothed down in southern lakes,
but it is difficult to guess because you
have two nonlinear variables going on at
the same time.  Biomass is not a fixed
number, and we measure it only once a
year because of the difficulty.

Q (Pam Shubat, Minnesota Department
of Health): Has that variation been
tested?  Has anyone gone out and
collected the field data?

Dr. Porcella:
     Yes, there is a very good data set
from Davis Creek Reservoir in Califor-

                                                                    National Forum on Mercury in Fish
                      nia. Darryl Sloten has collected data,
                      and they do show a variation in mercury
                      concentration in a fish compartment
                      within the year. I couldn't tell you
                      whether it's on that order or not.

                      Q (Alan Stem, New Jersey Department
                      of Environmental Protection): I've
                      heard some suggestions regarding the
                      possibility of methylation within fish. I
                      think these suggestions have come from
                      some calculations of mass balance,
                      which don't seem to be able to account
                     for the amount of methylmercury in the
                      biomass, given concentrations in the
                      water column and in the sediment.
                      Have any of you come across anything
                      like that or any speculation on the
                     possibility that it might be true?

                      Dr. Porcella:
                          This has been a bit of a contro-
                      versy. John Rudd raised this issue
                      based on measuring methylation rates in
                      fish. It can occur within the laboratory,
                      but John feels now that it's not an
                      important process in nature. Using
                      tracers, which generally free you from
                     the difficulty of contamination, there is
                     no evidence of appreciable methylation
                      or demethylation within the fish.

                     Q (Jim Wiener, National Biological
                     Survey): I think there  have been some
                     applications ofbioenergetic models
                     where the modeler has been frustrated
                     by his/her inability to get enough
                     methylmercury into the fish to account
                     for the amount of mercury mass in the
                     fish. Some of the estimates of the
                     assimilation efficiency across the gut in
                     the earlier models were probably low
                     based on some of the laboratory-derived
                     data. But I think some recent applica-
                     tions ofbioenergetic models have shown
                     that more realistic estimates of assimila-
                     tion efficiency are on the order of 65-80
                     percent or greater. And some of the
                     estimated assimilation efficiencies used
                     in early models were as low as 20
                     percent. That may account for the

                     Q (Nicole Jurczyk, Environmental
                     Science & Engineering): Regarding
 crayfish data—and I've had a hard time
finding crayfish data—do you see any
 correlation between what's in the
 crayfish for total mercury versus small
fish versus large fish? Are they about
 the same as what's found in the small
fish, or do you notice that crayfish have
 generally more mercury?

 Mr. Bloom:
     Data are limited, but within that
 data set it does appear that crayfish
 numbers are similar to small fish data.

 Q (Arnold Kuzmack, U.S. EPA, Head-
 quarters): You showed your estimate of
 the proportion of anthropogenic mer-
 cury emissions that were locally- or
 regionally-deposited versus globally as
 being the result of balancing your mass
 balance. So as a residual it would
accumulate all of the errors in the rest
of your estimate. I wondered how
accurate is that? Could it be 20 percent
or 80 percent or 10 percent, rather than
50 percent?

Dr. Fitzgerald:
     I think it's a factor of two that you
would have to worry about there. The
mass balance model provides a frame-
work for asking questions. I also wish
to clarify something in Don Porcella's
presentation.  When Don was showing
decreases in deposition in Minnesota,
we must bear in mind that this would
reflect what's occurring on a local scale
and may not apply  globally. I'm
concerned about mixing local issues
with global issues.  Sometimes when a
small piece of the Earth's surface is
considered, it is not surprising to find
mercury deposition to have diminished
over recent times. But I suspect that on
a global scale that is not evident. There
is evidence for gaseous mercury con-
centrations in the atmosphere that may
have been increasing during the same
period  of time over the Atlantic. Those
data are somewhat controversial.
Nevertheless,  we have in one part of the
globe what appear to be increasing
concentrations, and in another part of
the globe we have decreasing concentra-

Conference Proceedings
tions. We have to resolve the causes of
such variability.

Q (Arnold Kuzmack, U.S. EPA, Head-
quarters): This is significant from a
control strategy point of view since if
you're in an area where your lake
limnology is such that you get high
methylation rates, can you deal with
your problem by limiting regional
emissions, or would that be ineffective?

Dr. Fitzgerald:
     I agree completely that you must
resolve local/regional effects in any type
of management strategy. Indeed, if you
could eliminate local deposition in
certain areas mercury concentrations in
fish should decrease.

Q (Russell Isaac, Massachusetts Depart-
ment of Environmental Protection):
Regarding your mercury model, in
looking at some of those variables, is
there something general you could say
about the sensitivity analysis of the
model in terms of helping direct field
investigations? Is the model based on
data from an ecoregion or a particular
part of the country where you wouldn't
necessarily want to extrapolate to
tropical climates?

Dr. Porcella:
     In regard to your second question,
the model was developed in northern
Wisconsin and probably applies prima-
rily in that ecoregion for the coefficients
that we've obtained so far.  One of the
tasks that I showed is that we are going
to begin to apply the model to Florida
data.  It will be an important application
because it will allow us to test how
transferable that model is. We have
applied the model in other lake systems
and it seems to work reasonably well,
but we don't have the kind of data that
we had in Wisconsin to test them on.
     In response to your first question,
we've felt that those variables were
important. One of them is pH. It's been
shown to be a factor that correlates with
mercury concentrations in fish. So when
we picked seven lakes, we picked seven
seepage lakes with a range of pH and a
range of DOC (dissolved organic car-
bon). There are other
local conditions that    ______
affect mercury
uptake. One is
trophic levels. With
more productive
systems getting the
same amount of
mercury, you'll get
The amount of
mercury coming in     —————
has an effect on the
response of the system, so you can't
ignore the loading, whether it comes
from the atmosphere or the drainage
system.  We think that the amount of
mercury accumulated is to a large extent
driven by local conditions.

Q (Rick Hoffmann, U.S. EPA,  Head-
quarters): Relating to sediment, if the
hypoxic zone is a narrow zone where
the methylation is taking place, is that
an important factor to consider when
you're sampling the sediments?  In
other words, when you're doing sedi-
ment cores and trying to estimate
methylation, is the hypoxic layer really a
very thin layer or does it vary from
place to place?

Dr. Gilmour:
     Yes, it's something important to
consider. When we've looked at depth
profiles of methylmercury in sediment,
the zone where you see high methylation
is generally right near the sediment
surface or within centimeters of the
sediment surface. If you take a bulk
sample that's 10 centimeters down,
you're certainly going to get a different
number than if you sample the top couple
centimeters of sediment. The zone where
methylmercury is highest does vary from
system to system. We generally take the
top 4 centimeters as a rough average,
although it does vary within the 4
centimeters. If you take a very deep
sample, you effectively dilute the meth-
ylmercury concentrations of the surface
sediments in almost every occasion.
**.  . . we have in one part of
the globe  what appear to  be
increasing concentrations,
and in another part of the
globe we  have decreasing

       National Forum on Mercury in Fish
                     Q (Mark Armstrong, Arkansas Game
                     and Fish Commission): You mentioned
                     in one of your slides the 28-day holding
                     period that EPA recommends and you
                     referenced it to your water samples.
                     Are you aware of anything that docu-
                     ments the decay of mercury over time
                     for holding periods for fish? Is that a
                     reasonable period? Are you aware of
                     any studies documenting that we need
                     to consider a [mercury decay rate] in
                     fish tissue analyses?

                     Mr. Bloom:
                          Fish tissues definitely do not
                     decay in 28 days. Studies to docu-
                     ment that have not been done because
                     they're expensive. There is anecdotal
                     evidence from Finland, however,
                     from samples that were stored frozen
                     that gave identical results after 3
                     years. Your biggest risk in storing
                     fish is losing water.

                     Q (Mark Armstrong, Arkansas Game
                     and Fish Commission):  Regarding the
                     natural background variability that you
                     observe in fish tissue mercury concen-
                     trations taken from the same body of
                     water at the same time at the same age,
                     there were some age data on yellow
                     perch presented that were actually
                     pretty close together.  What was the
                     spread over those same aged fish?

                     Dr. Porcella:
                          There was roughly a 10-15
                     percent coefficient of variation. But if
                     you went from the same 1-year yellow
                     perch and looked at it at different years,
                     you would see differences that were
                     driven probably by local conditions that
                     vary between the  years; for example, a
                     drought year.
                     Bloaccumulation of Mercury in

                     Dr. James Wiener, U.S. Fish and
                     Wildlife Service
                     Q: How are you going to protect [water-
                     sheds] when the problem is basically
 atmospheric? As managers, we look at
 [the atmospheric contribution] and say we
 have to build a roof over the place.

 Dr. Wiener:
     You need to go to your geochem-
 ists and atmospheric people and ask
 them the same  question.  I would be
 concerned with mercury that's associ-
 ated with particulates, for example.
 The idea that you have more localized
 deposition of certain mercury forms.
 You might not  want to site something
 like an incinerator that puts out par-
 ticulate mercury near a system.

 Q (John Cicmanec,  U.S. EPA): Re-
 garding the slide where you contrasted
 the marine ocean fish, the body
 outside Australia, and the Wisconsin
 lake, the top had a concentration of
 2300 marine fish and then 1000.
 Should we take those numbers literally
 or are you just trying to point out the

 Dr. Wiener:
     They analyzed several organisms
 within each of those trophic layers, and
 what I presented was the arithmetic
 mean for the number of groups analyzed.
 In marine systems we certainly have
 longer food chains than we do in many
 fresh waters.  And we also have some
 very large long-lived fish that are
 capable of accumulating high concentra-
 tions of mercury.

 Q: I've analyzed a lot of prey organ-
 isms in a contaminated bay in Texas,
 and I don't see  this big difference
 between the predators and the prey
 that you've pointed out for fresh water
 and in the Australian case.  I've
 analyzed a large number  of different
prey, and they are all very similar in
 concentration to the larger fish for
 total mercury.

Dr. Wiener:
     It may  be that you have lower
trophic levels.  You may have a large
fraction of that  mercury present as
inorganic mercury.

Conference Proceedings
Q:  But why don't you still see that
biomagnification that you're talking

Dr. Wiener:
     Methylmercury biomagnifies in
food chains. Inorganic mercury does not
biomagniry. My guess is that your data
would show biomagnification if the
analysis were limited to methylrnercury.

Mercury in Wildlife

Dr. Chuck Facemire, U.S. Fish and
Wildlife Service

Q (Rob Reash, American Electric
Power): Regarding your diagram of
Florida panthers showing methyl-
mercury to be the only form  in the
hair, inorganic forms in liver, can you
try to speculate why this distribution
is the way it is?  Is it because of
steady state condition—methyl going
to the hair has maxed out, is satu-
rated—or is it just a differential
affinity for various body parts for
different forms of mercury?

Dr. Facemire:
     I think it is a steady state equilib-
rium condition, at least in the  hair,
because they're constantly exposed.
However, total mercury in the liver, as
in the blood, is made up of both inor-
ganic and organic forms.  This is due to
the fact that animals  ingest both types.
Methylmercury is easily assimilated into
some body tissues, whereas inorganic
mercury, for the most part, is  not.  The
liver, blood, and kidneys work to
remove inorganic mercury from the
body via feces and urine.  However,
some species appear to compartmental-
ize both inorganic and organic forms
differently. I don't really know why.

Q: I've seen reports of high mercury
levels in beluga whales in the  St.
Lawrence River.  Is there any  evidence
that mercury can accumulate  in fatty
tissues of marine mammals, and it has
any affinity for blubber or fatty tissue?
^Methylrnercury is easily
assimilated into some body
tissues, whereas inorganic
mercury, for the most part, is
Dr. Facemire:
     No, methylrnercury does not
accumulate in fatty tissues.

Q: Regarding marine fish meal used for
animal feeds, has there been a risk for
populations using that?

Dr. Facemire:
     There have been studies looidng at
the impacts. For example there's a lot
of that going into cat food.  A study
done in Canada demonstrated Minamata
disease in cats
fed with
fish. There is
also a study
where mink
ranchers also
ended up with
mink. It has           ..  .    .
caused mortal-
ity problems.  It is an important issue.
In Florida aibout 3 years ago someone
bought shark meat from the grocery
store and found 5-7 ppm. Also, tuna has
at various times contained very signifi-
cant amounts of mercury.

Q (Luanne Williams, North Carolina
Department of Environmental Health
and Natural Resources): Pertaining to
the percentage differences that you
referred to regarding the methylmercury
concentrations found in the fetus versus
the mother, are you referring to humans
or other animals?

Dr. Facemire:
     It happens in both. As I men-
tioned, one study on humans showed 30
percent more methylmercury in the red
blood cells of the human fetus than in
the mother; however, there was less
mercury found in fetal plasma than there
was in the maternal plasma, but not that
much less.  Overall, the fetal blood had
higher levels of mercury than did
maternal blood, so evidently mercury
crosses the placenta! barrier and very

      National Forum on Mercury in Fish
                      Q (Russell Isaac, Massachusetts Depart-
                      ment of Environmental Protection): Are
                      there regional influences that would
                      account for raccoon numbers?

                      Dr. Facemire:
                           Yes. Since the 1970s, for example,
                      in South Florida particularly, I mentioned
incinerators. Joe Delfino at the University
of Florida has been doing some work
looking at sedimentation rates in and
around some of these incinerators and
finds that there is in fact increased deposi-
tion in the sediments in the nearby areas.
So I think there are local sources that can
account for that.

               National Forum on
                  Mercury in Fish
Ecological Assessment of Mercuiy:
Contamination in the  Everglades
Jerry Stober
U.S. Environmental Protection Agency, Region 4, Environmental Services Division
    Since 1989, mercury has been found
    in elevated concentrations in
    various biota of the Florida
Everglades, including fish, the Florida
panther, raccoons, wading birds, and
alligators. The State of Florida has
issued a fish consumption advisory due
to mercury contamination, banning or
restricting the consumption of large-
mouth bass and other freshwater fish
from 2 million acres encompassing the
Everglades and Big Cypress National
Preserve (Figure 1).  Although highest
in the Everglades, mercury contamina-
tion in Florida also occurs in largemouth
bass in many other lakes and streams
across the state. Mercury in its most
toxic form, methylmercury, accumulates
in aquatic life and may pose increased
risks to consumers at the top of the food
chain (birds, mammals, and humans).
    Scientists currently know little
about the sources, extent, transport,
transformation, and pathways of mer-
cury in South Florida ecosystems.
Possible mercury sources hi South
Florida include natural mineral and peat
deposits, atmospheric deposition (global
and regional), fossil fuel-fired electrical
generating plants,  municipal waste
incinerators, medical laboratories, paint,
and agricultural operations. None of
these individual sources, however,
appears adequate to explain the vast area
apparently contaminated.
    The Region 4 Regional Environ-
mental Monitoring and Assessment
Program (R-EMAP) study will identify
and coordinate research, monitoring,
and regulatory efforts to address this
issue, using EPA's ecological risk
assessment framework. The study
focuses on the Everglades ecosystem,
which is composed of the largest deposit
of near-neutral peat in the world and
encompasses a region about 60 km wide
by 160 km long (9,600 km2) from south
of Lake Okeechobee to Florida Bay. The
             Study Area
Figure 1. Study area.

                                                                      National Forum on Mercury in Fish
                      study area includes the Everglades
                      Agricultural Area, three Water Conserva-
                      tion Areas including the Loxahatchee
                      National Wildlife Refuge, Big Cypress
                      National Preserve, Everglades National
                      Park, and other areas drained for urban
                      and agricultural development, resulting in
                      massive hydrologic modifications.
                           Seven policy-relevant questions have
                      been identified to guide the development
                      of this complex research and monitoring
                          • What is the magnitude of the
                            problem? What are the current
                            levels of mercury contamination in
                            various species? What ecological
                            resources of interest are being
                            adversely affected by mercury?
                          • What is the extent of the mercury
                            problem? What is the geographic
                            distribution of the problem? Is it
                          • Is the problem getting worse,
                            getting better, or staying the same?
                          • What factors are associated with, or
                            contribute to, methylmercury
                            accumulation in sensitive re-
                          • What are the contributions and
                            importance of mercury from
                            different sources?
                          • What are the risks to different
                            ecological systems and species
                            from mercury contamination?
                          • What management alternatives are
                            available to ameliorate or eliminate
                            the mercury contamination prob-
                           The Region 4 R-EMAP project is
                      focused on the first four questions above
                      and will initiate an ecological risk assess-
                      ment process. The project will integrate
                      and coordinate the efforts of various state
                      and federal agencies, including EPA's
                      Office of Research and Development and
                      Region 4 Envkonmental Services Divi-
                      sion; Florida's Department of Envkon-
                      mental Protection, Freshwater Game and
                      Fish Commission, Department of Health
                      and Rehabilitative Services, and South
                      Florida Water Management District; the
                      U.S. Army Corps of Engineers; the U.S.
                      Geological Survey; and industry repre-
                      sentatives.  Dr. Ron Jones of the South-
 eastern Environmental Research Pro-
 gram at Florida International University
 is cooperating closely with both the
 Everglades National Park and Region 4
 on this R-EMAP project.
 Cycling of Mercury in the
 Everglades System

     Significant quantities of mercury
 cycle through the air, water, and solid
 phases of the global environment. Mer-
 cury cycling through the atmosphere is
 estimated at 6 billion grams per year.
 Within this global background, certain
 regional areas may have higher atmo-
 spheric background concentrations due to
 nearby urban or industrial activity. In
 South Florida, the operation of solid waste
 incinerators and fossil fuel power plants
 has increased since 1940.  It is possible,
 therefore, that regional atmospheric
 mercury might also have increased over
 this time period.  Figure 2 depicts atmo-
 spheric deposition of mercury from urban
 sources into the Everglades. Figure 3
 shows a conceptual model of the bio-
 geochemical cycling of mercury in the
 Everglades ecosystem.

     The Region 4 R-EMAP study is
designed to answer questions that focus
on the extent, magnitude, and trends of
the mercury problem, as well as to
provide information for the initial phase
of the ecological risk assessment process.
All the activities are part of a larger
interagency effort to study mercury
contamination in the Everglades. Habitat
types that will be sampled include canals,
ponds, sloughs, wet prairies, sawgrass
marsh, and hammocks/tree islands.  Canal
sampling was carried out in September
1993, May 1994, and September 1994.
Four marsh transects that cross nutrient
gradients were sampled during April
1994. Seven canal structures have been
sampled biweekly since February 1994,
and the random marsh grid sampling is
scheduled to begin in spring 1995.

Conference Proceedings
Figure 2. Atmospheric deposition of mercury from urban sources into the Everglades.
                        1. Global and regional
                          atmospheric input
                          Hg°, Hg", MeHg
            4. Evasion Hg°   nitrogen and phosphorus
                                             9. Critical path analysis
                                               (birds and mammals, etc.)
3. Surface inflow
  Hg", MeHg
         2. Peat soils
           Hg", MeHg
                                                                             Outflow Hg ,
                                                                            MeHg transport
                 on/-^    -Nitrogen and-, • * '
       Idemethylation J"^ ..... ", phosphorus ^
       National Forum on Mercury in Fish
                      study. Finally, the Region 4 R-EMAP
                      study and other projects are jointly
                      developing analytical capabilities to allow
                      researchers to measure mercury at the
                      parts per trillion level in water and air.
                      Technical Approach

                           The Region 4 R-EMAP study will
                      test a number of hypotheses regarding
                      mercury contamination in the Everglades
                      ecosystem. These include the following:
                         • Mercury concentrations are
                            significantly increased by human-
                            induced (global and local) releases
                            to the air and subsequent wet/dry
                            deposition to the Everglades
                         • The Everglades Agricultural Area
                            is loading the downstream Water
                            Conservation Areas and the
                            Everglades National Park with
                            mercury and/or methylmercury.
                         • Eutrophication of the Everglades is
                            resulting in conditions conducive
                            to the methylation of mercury of
                            geologic origin in peat soils.
                           The Region 4 R-EMAP results and
                      findings will provide a basis for defining
                      an ecological risk assessment of the
                      impact of mercury on the entire system, as
                      well as on selected rare and endangered
                      species. This assessment will help
                      researchers determine the factors and
                      processes to be incorporated into a
                      mathematical model of the mercury cycle
                      in the Everglades ecosystem.
                     Sampling Site Selection and

                          Region 4 R-EMAP scientists are
                     using a random, probability-based
                     sampling strategy based on the EMAP
                     approach.  The strategy is designed to
                     be integrated with the assessment
                     strategy of the South Florida Geo-
                     graphic Initiative, a Region 4 program
                     to address  crucial environmental issues
                     in South Florida. The sampling grid is a
                     7x7-fold enhancement of the EMAP
                     base grid, resulting in a distribution of
points across the entire 9,600 square-
kilometer study area. The distance
between the individual points with the
full grid density is about 4 kilometers,
with a hexagonal area of about 13
square kilometers around each grid
point. Grid points in the Everglades
Agricultural Area, Water Conservation
Areas, and Everglades National Park
have an equal probability of inclusion.
The intensity of sampling will be
decreased in the areas outside this
primary study area.
Analytical Methods

     To determine the sources and
fluxes of mercury in the Everglades
ecosystem, the investigators need to
measure mercury accurately at ultra
trace levels (parts per trillion) in air,
water, sediment, soil, and fish tissue.
To accomplish this, researchers will use
a technique called automated cold vapor
atomic fluorescence spectrometry.
     The study employs "clean"
sampling protocols for air and water
to prevent contamination of the
samples during the collection, trans-
port, and storage phases.  "Clean"
protocols for laboratory analysis of
total mercury and methylmercury in
air, water, soil/sediment, and tissue
are also being developed by related
Initial Results

     The federal Central and South
Florida Rood Control Project (C&SF)
has sectioned the historic Everglades
with a system of canals and levees to
control water for urban and agricultural
development, resulting in pronounced
hydrologic modifications to the natural
system. As a part of this comprehensive
ecological risk assessment of mercury
contamination in the Everglades ecosys-
tem, a pilot study of canals was initiated
in September 1993 to determine the
extent and magnitude of total mercury
and methylmercury in water,  sediment

Conference Proceedings
and fish (Stober et al., in press). A
probability-based random sampling grid
was used to obtain consistent estimates
of mercury contamination over this large
geographic area. Two hundred canal
sampling locations were selected as
probability samples by associating grid
points on the sampling frame with
specific canal sections for independent
sampling cycles.  Of this number, 50
locations were randomly selected for
sampling in this pilot study. The
selected canal points were sampled from
north to south during a 6-day period.
Cumulative distributions with 95
percent confidence intervals were
calculated and used to determine a canal
system median concentration for se-
lected water, sediment, and fish con-
stituents. The percent exceedance of
each median, by hydrologic subarea,
was determined to demonstrate the
existence and direction of spatial
gradients in the system. North to south
(high to low) gradients were apparent
for total phosphorus, sulfate, dissolved
organic carbon, conductance, total
mercury, and methylmercury in water.
However, the gradients were reversed
from south to north for total mercury in
sediments and fish (Gambusia sp.).  The
greatest mercury concentrations in
Gambusia sp. occurred in the same
canals where largemouth bass had
previously been found to be most
contaminated.  Additional information
collected during subsequent sampling
efforts will be reported as analyses and
interpretations are completed.

Stober, Q.J., R.D. Jones, and D.J.
     Scheldt.  In press. Ultra trace level
     mercury in the Everglades ecosys-
     tem, multi-media canal pilot
     study.  /. Water Air Soil Pollut.


                  National Forum on
                     Mercury In Fish
 Atmospheric Deposition Studies
 in Florida
Thomas Atkeson
Florida Department of Environmental Protection, Tallahassee, Florida
         We (the Florida Department of
         Environmental Protection)
         found an unusual thing on the
Chapola River, a panhandle river west
of Tallahassee. It had more mercury
than we thought should be there. It led
several of us from the agencies on a
long-term monitoring program around
the state to see if there were excessive
levels of mercury in Florida. We really
didn't find much until we got down into
the Everglades region, where fish
sampled from a variety of spots aver-
aged about 2.5 parts per million (ppm)
total mercury in the edible portion of
largemouth bass.
    In about  1 million acres of the
Everglades—a large part of it compris-
ing water conservation areas 2 and 3 and
Everglades National Park—there was
mercury in the edible portions offish
exceeding 1.5  ppm. And in two sepa-
rate drainage areas, the Locksahatchee
National Wildlife Refuge and Taylor
Creek, the mercury concentrations were
somewhat lower, averaging a bit above
1 ppm.
    Florida is a state with active
media, and they jumped on this story
and kept it on the front pages for 2
years.  It certainly generated a lot of
attention among the agencies. It led us
eventually to work our way around the
state to describe the problem more
carefully. Today, most of the water
bodies of South Florida—particularly
 the Everglades, where the problem is
 worse—have come under these health
 advisories. A number of waterbodies
 are okay, such as Lake Okeechobee, and
 typically these are the waterbodies in
 Florida that are most "polluted" by
 traditional standards. A smattering of
 lakes and rivers from central Florida to
 the Big Bend area and all the way out to
 the panhandle are covered by these
 health advisories.  At least 1 million
 acres of surface waters here are under
 health advisories, and about another
 million acres scattered about the state.
 So, it is an extensive problem in our
 state, defined by a threshold of 0.5 ppm
 that results in the lower level of the
 advisories being issued.
    This issue has generated skepti-
 cism. Mercury levels baffle experts.
 Do we really know what we think we
 know?  There is also a good bit of
 criticism of the response of government
 to it. This sort of criticism gets a
 response.  Part of the response is to try
 to fill some of the knowledge gaps in
 terms of what is causing the problem
 and what we will try to do about it.
    We have been gratifyingly suc-
 cessful over the last 2-3 years in putting
together an interagency approach to the
problem, destling primarily with four
entities: the Florida Department of
Environmental Protection, U.S. EPA,
the South Florida Water Management
District, and the Florida Electric Power

                                                                     National Forum on Mercury in Fish
                      Coordinating Group working through
                      the Electric Power Research Institute.
                           We are getting into various areas
                      of research:  atmospheric, wetlands,
                      modeling. We are trying to do all of
                      this within the context of the ecological
                      risk assessment framework, trying to
                      define what  outcomes we are interested
                      in as we look toward sometime being
                      able to manage the problem in our state.
                      My talk today will be limited to the
                      atmospheric part.
                           Why are we so interested hi the
                      atmosphere? We heard earlier speakers
                      address some of the larger, global
                      aspects of the mercury problem and how
                      the manifestation of the problem today
                      appears to be primarily driven by
                      atmospheric emissions, long-distance
                      transport, and deposition. There are
                      also some peculiarities to Florida. The
                      southeastern Florida coast has the
                      highest concentration of municipal solid
                      waste incinerators hi the country, five of
                      them just upwind of the Everglades.
                      There was a tremendous amount of
                      attention focused on that issue as soon
                      as the mercury problem became evident.
                      Environmentalists dropped dioxin like a
                      hot rock and used the mercury issue to
                      hang around the necks of the incinera-
                            But it's not at all clear that there is
                      a one-to-one relationship between the
                      presence of these incinerators and the
                      problem in South Florida. First of all,
                      we should mention that four of the five
                      incinerators were not even online at the
                      time we collected the original fish that
                      resulted in these advisories.
                            There  are also some natural
                      processes that may have an effect. In
                      parts of southeastern Florida there is
                      often as much as 100 inches of rain hi a
                      year, most of it coming in the summer.
                      Mercury deposition is dominated by wet
                      deposition,  and I think that in general
                      mercury deposition is proportional to
                      total rainfall.
                            What  are the questions that we're
                      trying to answer with these atmospheric
                      studies?  Into what sort of frame of
                      reference do you put it? First, if you
                      think the sort of general process operat-
ing in the environment is an atmo-
spheric one, we have to ask the ques-
tion: Is the problem of the Everglades,
where the problem is disproportionately
severe or unusually severe, caused by
disproportionate atmospheric deposi-
tion? Is atmospheric deposition in
South Florida about the same as it is
everywhere else, or is it higher? Sec-
ond, if it is higher, is this the product of
localized emissions and atmospheric
processes, or is it caused by something
else? Third, if it is not apparently a  .
result of atmospheric processes, what is
it? Is it drainage and soil disturbance in
the Everglades agricultural area?  Is it
hydroperiod alterations within the entire
Everglades system?
     The first project to begin to  look
into  this, launched about 3 years ago,
was  called the Florida Atmospheric
Mercury Study (FAMS).  It is designed
to answer primarily one question: Is
mercury deposition in Florida different
from that in other parts of North
America? What are the loadings? I'm
not terribly interested in the atmosphere
as a complex phenomenon in and of
itself. I'm simply interested in it as a
loading term into  the aquatic system.
     I need to make it clear that I am
reporting on something that is not my
work. Don Porcella and I are project
managers on the various contracts.  The
scientists involved are Curtis Pullman,
Gary Gill, and William Landing.  The
first objective of the Florida Atmo-
spheric Mercury Study is to measure
mercury loadings into the Everglades
marsh, hi a fairly fine-scale, temporal,
and spatial way. We do this in compari-
son  to a marine background site:  is there
a difference between what we see
coming in off the Atlantic as it passes
over the urban area before it is deposited
out into the terrestrial part of South
Florida? Other objectives are to  mea-
sure the spatial and temporal variability
in mercury vapor concentrations, to
measure wet and bulk deposition of
mercury species, to measure mercury on
particulates directly, and to take meteo-
rological measurements with which to
correlate all of this. They are doing this

 Conference Proceedings
 by taking long-term, or monthly,
 integrated deposition samples. (This is
 done in an unattended and automated
 mode.) They are also taking weekly
 samples for mercury in the vapor phase
 and mercury on particulates. And the
 meteorology is being logged continu-
 ously while these other instruments are
      Lake Barko in northern Florida, a
 small seepage lake, is proposed to be the
 site where the mercury cycling model
 will be brought to Florida and
 re validated under Florida conditions.
 This lake has been used in a variety of
 hydrological and other atmospheric
 surface water interactions. It is a very
 well characterized waterbody, generally
 similar to the waterbodies in the Mer-
 cury in Temperate Lakes Project.  So, it
 is an excellent place to start to extend
 the range of the Mercury Cycling
 Model. The monitoring instruments are
 set up on a 48-foot tower.  We are not
 interested in all the mercury that may be
 traded around by local surface winds or
 locally resuspended dust. We are trying
 to look at the regional signatures
 impinging on this area, so the tower is
 put up high enough away from the
 ground-level dust and the bugs and
 other things that would contaminate
 samples.  The pumps, the electronics,
 and the control equipment are in a small
 portable building at the bottom of the
 tower. At the top of the tower, there is a
 standard atmospheric monitoring setup
 based around an aerokometric sampler,
 the workhorse of the acid rain studies.
 It is extensively modified to make it
 clean enough to take low-level mercury
 samples. The dry bucket is not really
 used for the mercury sampling, but the
 wet bucket is equipped with some
 Teflon® funnel/bottle combinations to
 collect wet deposition.
     A funnel made out of a bottle leads
 to a Teflon® tube with a vapor lock into
 a Teflon® receiving bottle to collect a
bulk mercury deposition sample. This
 device is left out for a full month and
collects all of the rain and dry fall. It is
roughly similar to the way that mercury
monitoring was done in the Nordic
 Monitoring Network, which the Swedish
 ran for several years. It collects every-
 thing that falls, as opposed to the
 aerokometrics, which collect wet only.
 You can infer something about dry
 deposition from any difference that you
 might see between these two collection
     In the polycarbonate housing there
 are several trains of mercury vapor
 sampling equipment. There are silica
 glass tubes, some of which have sec-
 tions of gold-coated sand. (It's the
 standard technique for taking mercury in
 the vapor phase.)  There are four of
 these sampling trains within this hous-
 ing, plus a blank.  These are cut on one
 each week of the month to collect a
 long-term integrated sample for each
 week of the month, plus a field blank.
     On the other side of the tower,
 there is a similar polycarbonate housing
 piped to the bottom of the tower through
 tubing that draws a vacuum through
 several open-faced flat filters to collect
 mercury in the particulate phase.  This is
 something that gave them a lot of
 problems early on, but they've been
 collecting particulate samples for about
 a year now. Each one of these filter
 systems is cut on sequentially for part of
 each week, each of the four  weeks of a
     These towers are to be located in
 nine areais in Florida. We're putting
 most of our money and effort into South
 Florida to try to get a fairly fine-
 resolution spatial picture to see whether
 or not patterns of deposition in South
 Florida can tell us anything  about the
pattern that we see of mercury in fish in
 sediments in water. What are the results
 of FAMs after it's been in operation to a
 limited degree for about 2 years and we
now have over a year at four sites in
 South Florida and about 6 months at
 another site in North Florida? First,
 what are average annual deposition
rates? The one site in North Florida
seized deposition of approximately 10
micrograms per square meter per year.
This is very similar to what you'll see in
other parts of North America.  South
Florida, however, is different. The

      National Forum on Mercury in Fish
                      average deposition among the sites'runs
                      about double that of the site in North
                      Florida, 20 micrograms per square
                      meter per year. In South Florida there is
                      a strong seasonality.  Summer deposi-
                      tion accounts for about 95 percent of the
                      annual deposition.  The rainfall concen-
                      trations are about 5-fold higher than
                      they are in the winter, and the amount of
                      rain is greatly elevated. The summer-
                      time deposition is exacerbated by both
                      the quantity of rain and the concentra-
                      tion of mercury in that rain, which is not
                      what we expected.
                           There is little correlation of
                      mercury with other trace elements that
                      are being analyzed in these samples.
                      Dr. Landing is doing extensive analysis
                      for other ions and trace elements in
                      these samples to attempt to correlate
                      these with fingerprints of certain
                      sources. You can see a clear sea salt
                      signature, for example, in the samples.
                      You can see the Sahara dust when it
                      blows over. You can occasionally see
                      some influence of other sources.  But
                      these do not correlate with mercury
                           The mercury vapor concentrations
                      in all of the sites, North and South
                      Florida, are very ordinary. The average
                      among all the sites is about 1.6 nano-
                      grams per cubic meter, plus or minus a
                      very small amount.  The seasonality in
                      the North Florida site is not significant.
                      Within the South Florida region we do
                      not yet have enough sites running for a
                      long enough period of time to say
                      whether there are any spatial differences
                      there or not.
                           We've also had some other
                      projects running that are fairly small in
                      scope. We've been collaborating with
                      Jerry Keeler, University of Michigan,
                      who has been heavily involved in the
                      EPA Great Lakes studies. We've done
                      some limited monitoring  in the urban
                      area of South Florida to answer the
                      question very much on people's minds:
                      Does the area source where 5 million
                      people live, plus a small number of
                      point sources—the southeastern coastal
                      area—contribute significantly to re-
                      gional mercury deposition out into the
Everglades? This question is frequently
asked. It is difficult to answer.
     Jerry takes short-term event
rainfall samples, which allow you to
discriminate sources much better than
the long-term integrated samples of
FAMS. He also takes very high fre-
quency meteorological measurements in
conjunction with that, that allow you to
back-calculate wind trajectories and so
forth. He is doing both gas phase and
bulk mercury sampling. He can use this
to do source-receptor modeling.
     The results from Jerry Keeler's
studies do not in all cases lead us to the
same conclusions  that we see from
FAMS today. First, Jerry, who works
primarily in Michigan around some very
dirty sites, sees rain concentrations that
blow his mind. Broward County,
Florida, where he's done this work, is a
garden variety industrial area compared
to Detroit and Chicago. Yet rain
concentrations in his samples are as
high as 30-40 nanograms per liter. He
sees source signatures in some of his
samples. He sees some contribution
from wind trajectories in the Tampa Bay
area, and he can see signatures from
some of the individual sources in the
Broward County urban area. However,
the one thing he can't tell, using the
amount of data that he has at the present
time, is whether these sources appear to
be quantitatively significant for the total
long-term deposition.
     This leads us to the point that
today there are several paradoxes, or
potential conflicts, among the various
work that we have going on. First, the
urban sampling shows correlation with
sources. The FAMS data, which smooth
out individual rain events, do not show
that these sources can reasonably be
seen to predominate the deposition.
Second, the FAMS marine background
site shows mercury deposition that is
approximately as  high as what we see on
the mainland. We have to say that this
blows our minds.  We expected to see
relatively clean air coming in off the
South Atlantic and the Gulf and that we
would look at the differences of those
clean air masses as they moved over the

Conference Proceedings
urban area. But the fact is, where
FAMS has seen an average of about 20
micrograms per square meter per year,
in the first few months of the marine
background site you have to estimate an
annual rate of about 17 micrograms per
square meter. It is not much different.
It suggests that  there may be some
source in the Caribbean region, some
unusual meteorology going on. No one
knows quite what to think of this.
     A third paradox is that in some
sediment work that has shown long-term
increases in mercury deposition to
Everglades soils,  The apparent mercury
accumulation rates of those soils, even
at depths where the rates are more
stable, are double to triple the highest
estimates that we have for the atmo-
sphere. This does not add up. I don't
know how we put those two things
     The upshot of all of this is that we
are trying to plan to do some coordi-
nated high-frequency sampling with the
higher density monitoring network in
the urban areas  of Broward County and
Dade County next summer, involving
Dr. Keeler and the FAMS group.  We
want to resolve  some of these para-
doxes. We need to get a better answer
to the question of whether or not local
sources in this area are contributing
significantly to deposition in another
     South Florida is a good place to
address these questions.  Where Jerry
Keeler works in Michigan, his ability to
discriminate sources and try to figure
out what's going on is compounded by
the fact that there are regionally elevated
mercury levels in the industrial heart-
land of America. Regardless of the
wind trajectory impinging on his
samplers, he is seeing a plethora of
sources and it's hard to separate them.
In South Florida the meteorology is
simpler hi that in the summer the
predominate wind trajectory is coining
from the east and south and there is not
presumably a regionally elevated
background concentration in this area.
What you're seeing is the uncorrupted
marine air coming in off the coast,
picking up whatever it will from purely
local sources. You can try to tease out
the local-scale contributions without the
interference of a regionally increased
background. I look forward to this
project next summer.


                  National Forum on
                     Mercury in Fish
 Watershed Effects on Background
 Mercury Levels in  Rivers
 lames P. Hurley
 Bureau of Research, Wisconsin Department of Natural Resources, Monona, Wisconsin, and
 Water Chemistry Program, University of Wisconsin, Madison, Wisconsin
         Water quality in individual
         rivers results from both
         natural and anthropogenic
 influences in the watershed. Concentra-
 tions of chemical constituents in a river
 water sample reflect a net result of
 specific processes such as chemical
 weathering, adsorption/desorption to
 various organic or inorganic matrices,
 sediment resuspension, atmospheric
 deposition, or direct point source inputs.
 This is especially true for mercury,
 which exhibits  numerous transforma-
 tions in atmospheric, soil, and aqueous
 systems. Importantly, the methylated
 form of mercury has been shown to
 bioaccumulate in the aquatic food chain
 and pose a significant risk to human
 health. It is thus important to assess
 factors that affect transformations and
 bioavailability of mercury in aquatic
     Our understanding of mercury
 cycling in natural waters has been aided
 by recent advances in low-level analyses
 of total mercury, elemental mercury,
 and monomethylmercury. Using these
 techniques, investigators are currently
 assessing complex mercury water
 column cycling processes in lacustrine
 systems. Specifically, a detailed study
 of mercury cycling in lakes in northern
Wisconsin has helped identify pathways
and processes responsible for mercury
bioaccumulation through the food chain
(Watras et al., 1994). By using a mass
 balance approach on seepage-type
 (precipitation and groundwater-domi-
 nated) lakes, investigators have identi-
 fied that atmospheric deposition of
 mercury was the predominant external
 source of mercury to the lake, and that
 this input was sufficient to account for
 all of the mercury present in lake water,
 seston, fish, and sediments (Fitzgerald
 and Watras, 1989).  This type mass
 balance helped in understanding the
 unusual observation of elevated levels
 of mercury in fish from waters remote
 from point sources.  The mass balance
 also identified significant internal
 recycling of mercury.  In predatory fish,
 the predominant form of mercury
 accumulating in fish tissue is in the
 methyl form. In atmospheric deposi-
 tion, methylmercury was low, typically
 in the range of 1-2 percent or less of
 total mercury (Fitzgerald et al., 1991).
 Significant internal cycling and bio-
 transformations were responsible for
 conversion of total mercury to methyl-
 mercury, leading to significant bioacc-
 umulation in higher trophic levels. In
 summary, these results demonstrated
 that a relatively small amount of exter-
 nally delivered mercury delivered to an
 aquatic system can be rapidly transferred
 through the food chain of seepage laikes.
    In drainage lakes however, direct
 atmospheric mercury sources might not
be the sole source of externally derived
mercury inputs. One must also consider

                                                                    National Forum on Mercury in Fish
                      riverine sources as input vectors.
                      Although the initial source of mercury
                      to some rivers might have been derived
                      as atmospheric deposition, significant
                      complexation and transformations might
                      occur prior to delivery to a receiving
                      water.  The extent of these transforma-
                      tions may depend on the type of water-
                      shed that receives atmospheric deposi-
                      tion. For example, in watersheds that
                      exhibit high  degrees of erosion, sus-
                      pended particle loads in an erosional
                      watershed might produce sites sufficient
                      for mercury  sorption and transport. In a
                      separate watershed, high chloride levels
                      might be important for complexation
                      and transport hi the dissolved phase.
                      For these and related reasons, when
                      evaluating the importance of specific
                      transport processes of mercury in rivers,
                      it is important to limit variables such as
                      complexity of a watershed during site
                      Wisconsin Background Trace
                      Metal Study

                           lii 1991, the Wisconsin Depart-
                      ment of Natural Resources began the
                      Wisconsin Background Trace Metals

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3 4-
2 -

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5 5



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dau from Bablarz and Andren (1994)
 Figure 1.  Mercury in Wisconsin rivers, 1991.
Study. From a regulatory standpoint,
accurate assessment of trace metal levels
in rivers is extremely important when
issuing discharge permits for a given
waterway. The "background" trace
metal values obtained from upstream
river sites helps to determine discharge
levels that are based on dilutional
capacities or nondegradation levels of
receiving waters. Prior to this study,
however, strict adherence to trace metal
clean techniques had not been followed
when obtaining or analyzing the
samples used for calculation of dis-
charge limits.
     The fkst phase of this study,
conducted in spring and fall 1991, was
limited to major rivers basins in the
State of Wisconsin. The results for
mercury, summarized by Babiarz and
Andren (1995), suggested that during
high-flow periods hi spring, mercury
levels in the rivers were higher than
during low flow in fall (Figure 1).
Interestingly, all mercury concentrations
measured in these rivers were below 10
ng/Lr1, a level that is at least 5-10 times
lower than the detection limit of previ-
ously used techniques.
     Results of the first phase of the
study provided the groundwork for
             future phases of the study.
             Since site selection in
             Phase I was based on
             major river basins of the
             state; the data produced
             did not allow for a true
             comparison of effects of
             watersheds on trace metal
             levels. Therefore, in
             Phase II, we chose sites
             nearer to headwaters to
             enable the comparison.
             Sites were chosen to
             represent "Relatively
             Homogeneous Units"
             (RHU, from USGS
             terminology) reflective  of
             individual land use
             patterns in a given water-
             shed. Sites selected
             contrasted land use and
             land cover among differ-
             ent surficial deposits and

 Conference Proceedings
 bedrock types. Land use/land cover
 classifications (based on GIS data of
 watersheds) were grouped as Forest and
 Wetland, Agricultural/Forest, Agricul-
 tural Only, Urban, and Integrator
 (Integrator sites were a subset of six
 sites from Phase I).
      Similar to Babiarz and Andren
 (1994), we observed an increase in
 mean unfiltered mercury (total mercury)
 in spring (7.9 ng/1) over fall (3.5 ng/1)
 for all sites in the study.  Classification
 of sites based on watershed type yielded
 interesting comparisons. Although all
 site groupings showed an increase in
 mercury during spring, major differ-
 ences were observed among groups
 based on particle partitioning and total
 mercury levels (Figure 2). Highest
 mean total mercury concentrations were
 observed in Urban watersheds during
 high flow in spring.  Interestingly, the
 lowest mean total mercury concentra-
 tions were observed in Urban sites (and
 Agriculture Only) during base flow in
 fall. At Integrator sites, spring to fall
 total mercury  concentra-
 tion differences were
 slight and particle parti-
 tioning was similar (60
 percent and 67 percent in
 dissolved form for fall and
 spring, respectively).
 Perhaps the greatest
 difference among group-
 ings was that in Wetland/
 Forest sites, total mercury
 was mainly in the filtered
 phase during both sea-
 sons. In contrast, in-
 creased mean total
 mercury levels in agricul-
 ture-associated sites were
 reflective of a greater
proportion of mercury
 associated with particulate
     Watershed yields,
calculated from concentra-
tion, flow, and watershed
area, provide a more
instructive tool than
mercury concentration for
comparison among
               watershed types (Figure 3).  Greater
               differences exist between spring and fall
               comparisons due to the inclusion of flow
               as a factor in computing yield. The
               differences between spring and fall in
               Urban sites is particularly noteworthy.
               Also important is the three- to five-fold
               higher yield from Wetland/Forest sites
               when compared to Agricultural/Forest
               and Agriculture Only sites. These
               observations of differences between
               wetland/forest and agricultural sites are
               most likely due to difference in organic
               matter complexation and transport
               among watershed types.  In agricultural
               areas, mercury deposited by atmospheric
               deposition is most likely complexed
               with particulate organic carbon in soil
               zones. A small proportion probably
               leaches through to ground water and
               into streams. During high-flow periods,
               mercury is mostly transported on the
               particulate phase due to erosion.  On the
               other hand, in wetland zones, mercury is
               probably complexed and transported in
               the dissolved phase and transported with
      80 -
 •P 30
1 1 Fall 1992 j
Wm Spring 1 993
% as filtered

     20 -
     10 -
                                Land Use Type
Figure 2. Total mercury yields from various Wisconsin watersheds.

                                                          National Forum on Mercury in Fish
                      dissolved organic carbon (DOC). DOC
                      is present at high levels in both surface
                      and pore waters of wetlands.
                           During our study, we also col-
                      lected samples for methylmercury at a
                      subset of sites. Similar to total mercury,
                      mean levels were higher in Wetland/
                      Forest than Agricultural/Forest sites.
                      Unlike total mercury, however, highest
                      methylmercury concentrations were
                      observed during base flow in fall at
                      Wetland/Forest sites. These observa-
                      tions are similar to those of St. Louis et
                      al. (1994) for watersheds in the Experi-
                      mental Lakes Area of Canada, where
                      investigators also found greater methyl-
                      mercury levels in the warmer months in
                      wetland zones. Their conceptual model
                      suggests that methylmercury is formed
                      within wetlands and transported either
                      downstream or to adjacent lakes. It is
                      suggested that for lakes that have
                      wetland influences, in-lake production
                      might not be the only site for methyla-
                      tion. Transport of methylmercury
                      produced within wetlands might be an
                      important delivery mechanism for
                      subsequent food chain bioaccumulation
                      in receiving waters.
                           A comparison of methylmercury
                      yield to percent wetland in watersheds
                      of our Wetland/Forest sites (Figure 4)
I	1 Fall 1992
    Spring 1993
% as filtered
                         Watershed Type
Figure 3.  Total mercury in Wisconsin rivers.
                                                    further shows the effects of wetlands on
                                                    methylmercury levels in rivers. During
                                                    both spring and fall, a significant
                                                    correlation existed between the two

                                                         The results of the Wisconsin
                                                    Background Trace Metal Study have
                                                    shown that partitioning and speciation
                                                    of mercury in Wisconsin rivers is
                                                    strongly influenced by land use and land
                                                    cover characteristics of the watershed.
                                                    Highest total mercury and methylmer-
                                                    cury yields were observed from sites
                                                    that passed through wetlands. Transport
                                                    of mercury through watersheds is most
                                                    likely affected by strong partitioning
                                                    with organic carbon.  Our observations
                                                    of methylmercury yields concur with
                                                    those of other investigators and support
                                                    the hypothesis that wetlands are net
                                                    producers of methylmercury to aquatic

                                    This Wisconsin Background Trace
                               Metal Study was funded by the Wiscon-
                               sin Department of Natural Resources,
                               Bureau of Water Resources Manage-
                               ment, David Webb, project liaison.
                               Laboratory analyses were performed by
                               Christopher Babiarz and Janina Benoit
                               at the University of Wisconsin-Madison,
                               Water Chemistry Program.

                                                     Babiarz, C.L., and A.W. Andren.  1994.
                                                         Total concentrations of mercury in
                                                         Wisconsin lakes and rivers. Water
                                                         Air Soil Pollut. In press.
                                                     Fitzgerald, W.F., and C.J. Watras.
                                                         1989.  Mercury in surficial waters
                                                         of northern Wisconsin. Sci. Tot.
                                                         Environ. 87/88:223-232.
                                                     Fitzgerald, W.F, R.P. Mason, and G.M.
                                                         Vandal.  1991. Atmospheric
                                                         cycling and air-water exchange of

Conference Proceedings
                              1.4 -
      mercury over mid-
      continental lacus-
      trine regions.  Water
      Air Soil Pollut.
 Hurley, J.P., J.M. Benoit,
      C.L. Babiarz, M.M.
      Shafer, A.W.
      Andren, J. R.
      Sullivan, R.
      Hammond, and D.A.
      Webb.  1995.
      Influences of
      watershed character-
      istics on mercury
      levels in Wisconsin
      rivers. Environ. Sci.
      Technol. In press.
St. Louis, V.L., J.W.M.
      Rudd, C.A. Kelly,
      K.G. Beaty, N.S.
     Bloom and R. J.
     Flett.  1994. Impor-
     tance of wetlands as sources of
     methyl mercury to boreal forest
     ecosystems. Can. J. Fish. Aquat.
     Res. In press.
Watras, C.J., N.S. Bloom, RJ.M.
     Hudson, S. Gherini, R. Munson,
     S.A. Claas, K.A. Morrison, J.P.
     Hurley, J.G. Wiener, W.F.
     Fitzgerald, R. Mason, G. Vandal,
     D. Powell, R. Rada, L.  Rislove, M.
     Winfrey, J. Elder, A.W. Andren,
     C. Babiarz, D.B. Porcella, J.W.
                                                   Percent Wetland Area in Watershed
                         Figure 4. Wisconsin rivers - Forest and Wetland sites.
                                            Huckabee. 1994. Sources and
                                            fates of mercury and methylmer-
                                            cury in Wisconsin lakes. In C.J.
                                            Watras and J. Huckabee, eds,.,
                                            Mercury as a Global Pollutant:
                                            Integration and Synthesis. Lewis
                                            Publishers, Chelsea, MI. In press.
                                       Zillioux, E.J., D.B. Porcella, and J.M.
                                            Benoit. 1993. Mercury cycling
                                            and effects in freshwater wetland
                                            ecosystems. Environ.  Toxicol
                                            Chem. 12:2245-2264.


                 National Forum on
   Day One: September 27,
 Questions and Discussion:
 Session Two
       After each speaker's presentation,
       an opportunity for questions and
        answers was provided.  Time
 was also allotted for a group discussion/
 question-and-answer session.

 Ecological Assessment of
 Mercury: Contamination in
 the Everglades Ecosystem

 Dr. Jerry Stober, U.S. EPA, Region 4

 Q (Nicole Jurczyk, Environmental
 Science and Engineering): You have
 both sediment and Gambusia data?

 Dr. Stober:
     Yes, we have water, sediment, and
 Gambusia data for the canals.

 Q (Nicole Jurczyk, Environmental
 Science and Engineering): Have you
 seen any trends between the sediment
 and the Gambusia?

 Dr. Stober:
     Yes, they seem to co-occur; if
 they're [mercury concentrations]  high in
 sediment, they're high in fish.

 Q: What is the difference regarding
sampling between canals and marshes?

Dr. Stober:
     I'm showing the first cycle of
canal samples. For the marsh data
 we've sampled the transects once, but
 the data still remain to be analyzed. I
 think we'll be developing a model
 specific to the marsh and another model
 specific to canals. They are totally
 different systems. The canals are
 anthropogenic modifications of the
 system, which set up a very good environ-
 ment for mercury methylation to occur.

 Atmospheric Deposition
 Studies in Florida

 Dr. Thomas Atkeson, Florida Depart-
 ment of Environmental Protection

 Q (Rick Hoffmann, U.S. EPA, Head-
 quarters): I know, that when you worry
 about atmospheric deposition for some
 nutrients like nitrates, the issue always
 arises about dry deposition and the
 difficulties in accurately measuring it
 (changes on the filters and so forth).
 Have you looked at that for the dry
 deposition of mercury?

 Dr. Atkeson:

     One of the other scopes of work
 that we have done together (several
 states) with the utility industry was to
pull together last spring an expert: panel
on atmospheric processes to try to  sort
out: what we know, what we think we
know, and what we'd like to know. The
questions of: what is the speciation of
mercury emission sources, how these
species may change in the immediate

                                                                   National Forum on Mercury in Fish
                      vicinity of the plume, if you will, and
                      how that translates into both wet and
                      dry deposition down-field are questions
                      that are very much open at the time.
                           As was alluded to earlier by
                      Dr. Fitzgerald and his global mercury
                      model, there is sort of a working
                      assumption that approximately 50
                      percent of the emissions from a combus-
                      tion emissions source are mercury in the
                      vapor phase, which enters the global
                      circulation and travels long distances.
                      The other half of emissions may be hi
                      some more reactive phase—some ionic
                      mercury species—which would  be
                      susceptible to being deposited locally or
                      regionally around the source.  It has
                      enormous implications for how you
                      think about the problem and how you
                      might ultimately think about the solution
                      to the problem. However, there is
                      currently no technique that will  allow
                      you to measure any of these ionic vapor
                      species. Will Straton is working with
                      Steve Lindberg to try to develop a mist
                      chamber sampling technique that would
                      capture the soluble species from the
                      atmosphere directly. That work is not
                      mature enough to report on at the
present time. Also, I'm sure there is a
great limitation in how any of these
samplers would sample those volatile
ionic species or how well they would
mimic natural dry deposition. It may
well be that the difference between what
we see in the mercury accumulation
rates for marsh land sediments (as
opposed to the deposition rates that we
see elsewhere) really relates to the
differing efficiency of vegetation in
scavaging dry deposition out of the
atmosphere as opposed to the very
artificial geometry of these collectors.
That is a central problem in any dry
deposition type of work.  There's going
to have  to be more work done to try to
develop the appropriate sampling

Watershed Effects on
Background Mercury Levels in

Dr. James Hurley, Wisconsin Depart-
ment of Natural Resources

No questions

                   National Forum on
                      Mercury in Fish
 Mercury Toxicfty:   An Overview
 Tom Clarkson
 University of Rochester, Rochester, New York
         Methylmercury is the predomi-
         nant mercury species compo-
         nent in fish and the main toxic
 species we are dealing with in this
 Forum. Divalent inorganic mercury may
 also be important in the toxicology of
 methylmercury to some extent. These
 inorganic forms are very important in
 the global distribution of mercury. I
 would also like to talk about the body's
 defenses against mercury and tolerance
     Mercury vapor goes into the
 atmosphere and stays there for a long
 time. The only way it gets back is to be
 oxidized to the divalent water-soluble
 form, and then it undergoes methylation
 and bioaccumulation in fish. Some of
 the highest levels of mercury in the
 atmosphere must have occurred about 2
 billion years ago, before oxygen was in
 the atmosphere and before there was any
 process of removal. Once oxygen
 appeared, it is very likely that cells were
 exposed to a divalent form of mercury at
 the same time they were exposed to
     Maybe it's no coincidence that the
 defense mechanisms we have against
 oxygen are also involved in  the metabo-
 lism of mercury. In particular, glu-
 tathione plays a very important role not
 only in the defense against oxygen but
 against mercury itself.
    The methylation of mercury
probably  occurred a long time ago.
 Jernelov, one of the discoverers of
 biomethylation, suggested that it was a
 detoxification mechanism for those
 primitive methanogenic bacteria at that
 time— divalent being more toxic. So,
 this reaction also may go back to arcane
     It is a mystery why methylmercury
 bioaccumulates to such a fantastic extent
 on the aquatic food chain. (We heard
 yesterday it was about a million-fold.)
 Fish do not excrete methylmercury, and
 that is presumably a big factor in the
 accumulation mechanism. But we don't
 know why fish fail to excrete methyl-
     The other interesting aspect of the
 bioaccumulation process is that fish are
 highly resistant to the toxic effects of
 methylmercury. The levels in fish —
 about 10 times what we can tolerate —
 seem not to affect the performance of
 the fish. Why do fish have this very high
 level of resistance as compared to us?
 Selenium has been suggested, but no
 clear factor has been identified to
 explain this higher resistance.
     Then, of course, the methylmer-
 cury gets to us. Methylmercury is
 coming from fish into humans, and only
from fish or marine mammals. No
clinical cases of poisoning have resulted
yet from the input from fish in this
manner. The poisoning cases I'm going
to talk about are those  which occurred
by accidental exposure to a fungicide or

                                                                     National Forum on Mercury in Fish
                      the release of methylmercury itself in
                           It's clear that humans do have a
                      tolerance, although much lower than
                      that offish. It is clear also that the
                      tolerance does not lie in the ability of
                      humans to exclude methylmercury.
                      Methylmercury gets into mammalian
                      cells very readily. It plays a trick on us.
                      It combines with the amino acid cys-
                      teine to form a complex that has a
                      structure very similar to the large
                      essential amino acid, methionine. As a
                      result, it gets a free ride on the large
                      neutral amino acid carriers into mamma-
                      lian cells. Since these carriers are
                      ubiquitous, we can expect that methyl-
                      mercury will penetrate all mammalian
                      cells. Of course it crosses the blood-
                      brain barrier.
                           So, if we have a tolerance to
                      methylmercury, it must lie somehow
                      inside the cell. Once it enters the cell as
                      a cysteine complex, methylmercury has
                      the remarkable property of jumping
                      from one SH group to another with great
                      speed. There must be SH groups that are
                      targets inside the cell, but we have not
                      identified these despite 30 years of
                      research. There are so many proteins as
                      potential targets that we haven't been
                      able to identify a single target with great
                           The good news is that inside cells
                      is glutathione, which has an SH group
                      and is present in cells at very high
                      levels. It's part of our oxygen defense
                      system. It also combines with methyl-
                      mercury and in doing so protects the
                      cell. Moreover, the methylmercury
                      complex itself is actively secreted out of
                      the cell on a glutathione conjugate
                      carrier. So from the point of view of the
                      cell, it's good news. From the point of
                      view of the blood-brain barrier, how-
                      ever, it's not, because the combination
                      of the cysteine and glutathione carriers
                      whips methylmercury  very handily
                      across the blood-brain barrier so that it
                      enters the interstitial tissue of the brain.
                      Here, the glutathione complex encoun-
                      ters the extracellular enzyme gamma
                      glutamyltranspeptidase, resulting in its
                      hydrolysis and the release of the amino
acid cysteine. This allows the methyl-
mercury-cysteine complex to enter the
brain cells. This might be one explana-
tion for the peculiar finding that meth-
ylmercury seems to be selectively toxic
to the central nervous system. This is a
highly mobile, highly reactive chemical
and why it should just poison the central
nervous system is a bit of a mystery.
But ease of access to the brain might
have something to do with it. Further-
more, many nerve cells have lower
glutathione levels than other mamma-
lian cells in the body, and this may also
contribute to the sensitivity of the
central nervous system.
     Another major detoxification
pathway is excretion. Methylmercury
enters the body as a cysteine complex,
forms the glutathione complex intracel-
lularly and is very rapidly and effi-
ciently secreted into bile as the glu-
tathione complex. It travels down the
biliary tree, enters the gallbladder and
again is hydrolyzed back to the cysteine
complex, which is reabsorbed. So we
have a large enterohepatic recirculation.
But some remaining methylmercury
finds its way into the GI tract, where a
group of microorganisms obligingly
demethylate it and form the poorly
absorbed inorganic divalent mercury,
which appears in the feces. Eighty
percent of methylmercury is excreted by
this pathway. It's really quite remark-
able that very few studies have been
'done on the microflora that are respon-
sible for detoxification. The
demethylation by microflora is very
important because it determines the half-
time of methylmercury in the body.
Antibiotics, for example, can affect that
population. It has been shown that if rats
are treated with antibiotics, the half-tune
of methylmercury increases.
     The demethylation also occurs in
other parts of the body. We had the
fortunate opportunity, about a year ago,
to examine an autopsy brain from a
female who had been exposed 20 years
ago to methylmercury. We compared
the mercury levels in her brain to those
of a reference brain. Her brain had
mercury levels about 100-fold higher

 Conference Proceedings
 than normal. And presumably that's
 been there for the last 20 years. The
 other astonishing thing is that the
 mercury is not methylmercury although
 she had been exposed to methylmercury;
 it's all inorganic. So whether this
 inorganic mercury, which clearly must
 have been formed in the brain, is a
 detoxification mechanism or whether it
 itself is exerting some toxic effect
 remains a matter of speculation at this
      When our defenses fail (as hap-
 pened in the Iraq outbreak), terrible
 things happen to the brain at very high
 doses. Methylmercury in the adult brain
 poisons certain areas. It has a focal
 effect. The cerebellum, for example, is
 affected,  but only certain cells are
 affected.  The visual cortex is affected.
 The neighboring cells are totally un-
 scathed. This is also another mystery
 about mercury. Why is it having this
 focal effect?
      One theory that's been around for
 10 years or more, is that  when methyl-
 mercury first enters the brain it damages
 all the cells. But certain cells, because of
 their size and their repair capacity, can
 overcome that damage, and these are the
 ones that we see surviving. So this
 pattern may not represent a property of
 methylmercury, but a characteristic of
 the nerve cells themselves—those that
 can repair and those that  cannot repair
 this damage.
     When this damage occurs, one sees
 a fascinating and alarming sequence of
 events, as we observed in the Iraq
 outbreak.  The period of ingestion of the
 methylmercury-contaminated bread was
 about six weeks. During the intake
 period, no signs or symptoms of poison-
 ing were experienced. Even after intake
 had stopped, the first symptom,
 paresthesia, did not appear for another
 month or so. This was followed by the
 insidious sequalae of more serious
 effects such as ataxia, slurred speech
 and the constriction of the visual fields.
Indeed, some victims ingested what
 would ultimately result in a fatal dose
without any effects, not even stomach
irritation, during the intake period.
       As opposed to the focal damage
  seen in the adult brain methylmercury
  appears to produce widespread damage
  to the developing brain. Methylmercury
  affects the development process. Prena-
  tal exposure is particularly dangerous
  because it is affecting a very basic
  process in the brain. In a section of a
  cortex of a child used as a control one
  can see the ordered layers of cells.
  However in a badly affected child from
  Iraq, one can see that these ordered
  layers are grossly disrupted.
      There are cellular theories  about
  how this is happening. One of the
  theories is that methylmercury affects
  cell division,  which is only occurring in
 the developing brain. In a study  on
 neonatal mice where brain development
 is still continuing, Sager and her col-
 leagues  demonstrated arrested cell
 division in both sexes. However, at a
 lower dose, only the male mice were
 affected. This is interesting because in
 Iraq it was the male infants who  had the
 more severe signs and symptoms versus
 the female. The basis  of this sex  differ-
 ence is a mystery.
     The most susceptible structure
 inside the cell is the microtubule system,
 which is responsible for cell division,  of
 the separation of the chromosomes, and
 is also responsible for cell movement.
 Cell migration is another basic property
 in the developing brain that is inhibited
 by prenatal exposure to methylmercury.
 The tubules are formed by a
 treadmilling process. It is believed that
 methylmercury combines with the SH
 groups in the tubulin subunits and stops
 the assembly end. And then, of course,
 at the disassembly end the depolymer-
 ization continues and the microtubule
     In conclusion, I do believe mat it is
 very important to look into the mecha-
 nisms of resistance and tolerance. If we
 could understand what the mechanisms
 of tolerance; are, we might be able to
understand when these are over-
whelmed. And it might be from this
biological point of view that we answer
the $60 billion question: "At what level
of methylmercury are our bodies safe?"


                 National Forum on
                   Mercury in Fish
Neurobehavioral Effects of
Developmental  Methylmercuiy
Exposure in Animal Models
Deborah C. Rice
Toxicology Research Division, Health Canada, Ottawa, Ontario
  JA  s a consequence of the tragic
 £^k outbreaks of human methylmer-
M.  Mkcury poisoning in Japan and
Iraq, substantial research effort has
focused on characterizing the develop-
mental effects of exposure to methyl-
mercury in animal models. Most of the
research has been performed in the rat,
including two large interlaboratory
collaborative studies, one in the United
States and one in Europe, in which the
effects of methylmercury were assessed
using a battery of behavioral tests.
Research in the monkey has focused on
characterization of sensory system
impairment produced by developmental
methylmercury exposure, in addition to
assessment of performance on measures
of cognitive function.
    Methylmercury developmental
neurotoxicity was first identified in the
mouse by Spyker et al. (1972), who
reported retarded growth and increased
mortality in pups exposed in utero, with
no obvious effect on motor function.
Neurotoxicity was revealed when these
mice were forced to swim, however,
manifested as abnormal swimming
movements and posture. Abnormalities
of various sorts were also observed as
these animals aged, including kyphosis,
obesity, and severe neurological deficits
(Spyker, 1975).
    A number of subsequent studies in
rats or mice exposed during several days
of gestation demonstrated gross neuro-
logical signs, changes in activity, or
impairment on simple learning tasks,
sometimes in conjunction with de-
creased maternal or pup weight, or
increased pup mortality (Geyer et al.,
1985; Cuomo et al., 1984; Eccles and
Annau, 1982a, b; Hughes and Annau,
1976; Inouye et al., 1985; Su and Okita,
1976). In a collaborative study involv-
ing six laboratories in the United States,
the effects of 2.0 or 6.0 mg/kg of
methylmercury on gestational days 6-9
were studied on negative geotaxis,
olfactory discrimination, auditory startle
habituation, activity, activity following
a pharmacological challenge, and a
visual discrimination task (Buelke-Sam
et al., 1985). Facilitation of auditory
startle at the high dose of methylmer-
cury was reliably observed across
laboratories, with inconsistent or
minimal effects on  activity, pharmaco-
logical challenge, and the discrimination
task,  in the presence of overt signs such
as decreased weight gain and delayed
developmental landmarks. Additional
research with a different battery of tests
using a subset of the rats from the U.S.
collaborative study revealed delayed
righting and swimming ontogeny,
decreased activity, and impaired com-
plex water maze performance (Vorhees,
     In a collaborative study in Europe,
dams were exposed to methylmercury in
drinking water during pregnancy and

      National Forum on Mercury in Fish
                      lactation. Delayed sexual maturity and
                      impaired righting and swimming ability
                      were observed in the offspring (Suter
                      and Schon, 1986). Assessment of
                      complex learning as measured by visual
                      discrimination reversal and spatial
                      delayed alternation revealed increased
                      response latencies and an increased
                      incidence of failure to respond during a
                      trial, with no effect on accuracy of
                      performance (Schreiner et al., 1986;
                      Eisner, 1986). In addition,  the pattern of
                      locomotor behavior in a complex
                      activity monitor differed between
                      control and methylmercury-treated
                      offspring, with treated rats exhibiting
                      less behavioral diversity. In a follow-up
                      study involving five European laborato-
                      ries, dams were exposed on days 6-9 of
                      gestation (Eisner et al., 1988). This
                      study in general confirmed results of the
                      previous study with respect to effects on
                      the spatial alternation and discrimina-
                      tion  task, as well as the altered pattern
                      of locomotor behavior in methylmer-
                      cury-treated offspring. In a pair of
                      studies (Musch et al., 1978; Bornhausen
                      et al., 1980), rat dams were gavaged
                      with methylmercury on days  6-9 of
                      gestation. Offspring were impaired in
                      their ability to perform a DRH schedule
                      of reinforcement, in which a number of
                      responses on a lever were required in a
                      specified (short) period of time. This
                      paradigm detected effects at the lowest
                      dose (0.01 mg/kg) of any study. Little
                      research has focused on the effects of
                      methylmercury exposure on sensory
                      system function in the rodent. In utero
                      exposure results in changes in cortical
                      visual evoked potentials (Zenick et al.,
                      1976; Dyer et al., 1978). Other effects
                      on performance observed in rodents may
                      well be due at least in part to sensory
                      deficits, but this possibility has appar-
                      ently not been explored.
                           A considerable  amount  of research
                      on the neurotoxicity of methylmercury
                      has been performed in monkeys. This
                      was undoubtedly in part a response to
                      the tragic episodes of human methyl-
                      mercury poisoning, and the recognition
                      of the limitation of the rodent as model
                      of methylmercury intoxication. It is well
established that in the adult human,
methylmercury preferentially damages
the sulci, particularly but not limited to
calcarine fissure. As a consequence, one
of the hallmarks of methylmercury
poisoning in adult humans is constric-
tion of visual fields. The monkey, like
the human and unlike the rodent, has a
brain with deep sulci. Constriction of
visual fields is also observed in adult
monkeys following chronic methylmer-
cury exposure (Merigan, 1980). Other
functional deficits in visual function
have also been documented in adult
monkeys exposed to methylmercury.
Deficits in low-luminance form vision
were detected on a visual discrimination
task; these effects preceded more global
visual deficits (Evans et al., 1974).
Decrements in detection of a flickering
stimulus at low luminance have been
observed in monkeys, that also demon-
strated constriction of visual fields
(Merigan, 1980). Decreased flicker
sensitivity has also been observed in
squirrel monkeys exposed to methyl-
mercury (Berlin et al., 1975). Monkeys
in these studies had blood mercury
levels of 2.0-3.0 ppm. Hypesthesia
(impaired sense of touch), another
typical sign of methylmercury exposure
in adult humans, has  also been observed
in adult macaque (Evans et al., 1975)
and squirrel monkeys (Berlin et al.,
     Since it was clear from the episodes
of human methylmercury poisoning that
the developing organism is more sensi-
tive to the effects of methylmercury
intoxication than the adult, much of the
research in monkeys has focused on the
effects of developmental exposure. One
series of experiments was performed at
the University of Washington in macaque
monkeys (Macaco.fascicularis) exposed
to methylmercury in utero (Burbacher et
al., 1988). Females were dosed with 50,
70, or 90 ug/kg/day of methylmercury,
resulting in steady state blood mercury
concentrations prior to breeding of 1.3,
1.6, or 2.0 ppm for the three dose groups,
respectively. Reproductive success was
severely affected at the two highest

Conference Proceedings
     Methylmercury-exposed infants
exhibited impaired memory on a visual
recognition task during infancy
(Gunderson et al., 1986, 1988); perfor-
mance on this task is highly predictive
of later performance on intelligence tests
in humans (Pagan and McGrath, 1981).
At 9 months of age, these monkeys also
displayed retarded development of
object permanence (Burbacher et al.,
1986), which tests development of the
infant's ability to realize that an object
placed out of sight is still present. This
same group of monkeys also displayed a
decrease in social play and an increase
in nonsocial passive behavior when
tested between the ages of 2 and 8
months (Burbacher et al., 1990). In
these studies, none of the infants showed
overt signs of methylmercury toxicity,
including reduced birth weight. In  a
follow-up study, this group of monkeys
was tested at 7-9 years of age on a
spatial delayed alternation task (Gilbert
et al., 1993). Monkeys exposed to
methylmercury in utero performed
better than control monkeys during the
initial phases  of the experiment, with no
differences between groups by the  end
of the experiment.
     Studies in this same species of
macaque have also been performed at
the Canadian  Health Protection Branch.
One group of five monkeys, presently
19 years old, was dosed with 50 ug/kg/
day of mercury as methylmercuric
chloride from birth to 7 years of age;
blood mercury concentrations during the
period of dosing were approximately
0.75 ppm. When these monkeys were 3
years of age, during the period of
methylmercury exposure, spatial visual
function was assessed under both high
(cone) and low (rod) luminance condi-
tions (Rice and Gilbert, 1982). Treated
monkeys were impaired under both
conditions in the absence of constriction
of visual fields. These monkeys also
exhibited impairment of high-frequency
hearing at the age  of 14 years, 7 years
after cessation of exposure to methyl-
mercury (Rice and Gilbert, 1992).
     Another study in the same labora-
tory examined the effects of in utero
plus postnaital exposure in the same
species of monkey. Females were dosed
with 10, 25, or 50 ug/kg/day of mercury
as methylmercuric chloride; blood
mercury levels averaged 0.37, 0.75, or
1.42 ppm during pregnancy. One, two,
and five infants were born from the
three dose groups, respectively. One
infant in the high-dose group was born
with signs of methylmercury poisoning
resembling those of human infants,
including motor impairment and nystag-
mus (Rice, 1983). Testing of these
monkeys during infancy and the juve-
nile period failed to reveal cognitive
deficits as measured on a discrimination
reversal task, although treated monkeys
performed differently from controls on
an intermittent schedule of reinforce-
ment (Rice,  1992). This group of
monkeys, including the monkey dosed
at 10 ug/kg/day, showed impaired
spatial visual function when tested
shortly after cessation of methylmercury
exposure at 4 years of age (Rice and
Gilbert, 1990).
     When the group of monkeys
exposed only postnatally until 7 years
of age was 13 years old, they began
exhibiting clumsiness not present
previously (Rice, 1989). Further
exploration revealed that treated
monkeys required more time to retrieve
treats than did nonexposed monkeys
and displayed abnormalities on a
clinical assessment of sense of touch in
hands and feet, despite the fact that
routinely performed clinical examina-
tions during the period of dosing had
not yielded abnormal results. These
results  are strongly suggestive of a
delayed neurotoxicity manifested, when
these monkeys reached middle age.
This observation was pursued in both
groups of monkeys by objective
assessment of somatosensory  function
in the hands: both groups of monkeys
exhibited impaired vibration  sensitivity
(Rice and Gilbert, 1994).
     The only report of cognitive
impairment in adult monkeys  exposed
to methylmercury developmentally is a
study in the squirrel monkey (Newland
et al., 1994), in which monkeys exposed

      National Forum on Mercury in Fish
                      during the last two-thirds of gestation
                      exhibited impaired ability to shift
                      response strategy on a complex test of
                      repeated learning.
                           The results from the animal data,
                      including studies in both rodents and
                      monkeys, suggest that tests of sensory
                      and/or motor function are more sensitive
                      indicators of methylmercury toxicity
                      than is assessment of cognitive end-
                      points. It is suggested that assessment of
                      sensory and motor function be included
                      in epidemiological studies exploring the
                      effects of developmental methylmercury

                      Berlin, M., C.A. Grant, J. Hellberg, J.
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                      Berlin, M., G. Nordberg, and J.
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Eccles, C.U., and Z. Annau. 1982b.
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Eisner, J., B. Hodel, K.E.  Suter, D.
     Oelke, B. Ulbrich, G. Schreiner,
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     Infant recognition memory and
     later intelligence. Intelligence
Geyer, M.A., R.E. Butcher, and K. File.
     1985. A study of startle and
     locomotor activity in rats exposed
     prenatally to methylmercury.
     Neurobehav. Toxicol. Teratol.
Gilbert, S.G., T.M. Burbacher, and D.C.
     Rice. 1993. Effects of in utero
     methylmercury exposure on a
     spatial delayed alternation task in
     monkeys. Toxicol. Appl.
     Pharmacol. 123:130-136.
Gunderson, U.M., K.S. Grant, T.M.
     Burbacher, et al.  1986. The effect
     of low-level prenatal methylmer-
     cury exposure on visual recogni-
     tion memory in infant crab-eating
     macaques. Child. Develop.
Gunderson, V.M., K.S. Grant-Webster,
     T.M. Burbacher,  and N.K. Mottet.
     1988. Visual recognition memory
     deficits in methylmercury-exposed
     Macaca fascicularis infants.
     Neurotoxicol. Teratol.  10:373-379.
Hughes, J.A., and Z. Annau.  1976.
     Postnatal behavioral effects in
     mice after prenatal exposure to
     methylmercury. Pharmacol.
     Biochem. Behav.  4:385-391.
Inouye, M., K. Murao, and Y. Kajiwara.
     1985. Behavioral and
     neuropathological effects of
     prenatal methylmercury exposure
     hi mice. Neurobehav. Toxicol.
     Teratol. 7:227-232.
Merigan, W.H. 1980. Visual fields and
     flicker thresholds in methylmer-
     cury-poisoned monkeys. In W.H.
     Merigan and B. Weiss, eds.,
     Neurotoxicity of the Visual Sys-
     tem., pp. 149-163. Raven Press,
     New York.
Musch, H.R., M. Bornhausen, H.
     Kreigel, and H. Greim.  1978.
     Methylmercury chloride induces
     learning deficits in prenatally
     treated rats. Arch.  Toxicol. 40:103-
Newland, M.C., S. Yezhou, B.
     Logdberg, and M. Berlin. 1994.
     Prolonged behavioral effects of in
     utero exposure to lead or methyl-
     mercury: reduced sensitivity to
     changes in reinforcement contin-
     gencies during behavioral trainsi-
     tions and in steady state. Toxicol.
     Appl. Pharmacol.  126:6-15.
Rice, D.C. 1983. Nervous system
     effects of perinatal exposure to
     lead or methylmercury in mon-
     keys. In T.W. Clarkson, G.
     Nordberg,  and P. Saaer, eds.,
     Reproductive and Developmental
     Toxicity of Metals, pp. 517-540.
     Plenum Press, New York.
	. 1989. Delayed neurotoxicity in
     monkeys exposed developmentally
     to methylmercury. Neurotoxicol.
      -. 1992. Effects of pre- plus
     postnatal exposure to methylmer-
     cury in the monkey on fixed
     interval and discrimination rever-
     sal performance. Neurotoxicol.
Rice, D.C., and S.G. Gilbert. 1982.
     Early chronic low-level methyl-
     mercury poisoning in monkeys
     impairs spatial vision. Science
	. 1990. Effects of developmental
     exposure to methylmercury on
     spatial  and temporal visual func-
     tion in monkeys. Toxicol. Appl.
     Pharmacol. 102:151-63.
	. 1992. Exposure to methylmer-
     cury from birth to adulthood
     impairs high frequency hearing in
     monkeys. Toxicol. Appl.
     Pharmacol. 115:6-10.
      -. 1994. Delayed somatosensory
     deficits in monkeys exposed
     developmentally to methylmer-
     cury. The Toxicologist 14:259.
Schreiner, G., B. Ulbrich, and R. Bass.
     1986. Testing strategies in behav-
     ioral teratology: II. Discrimination
     learning. Neurobehav. Toxicol.
     Teratol. 8:567-572.

      National Forum on Mercury in Fish
                      Spyker, J.M. 1975. Assessing the impact
                           of low level chemicals on develop-
                           ment: behavioral and latent effects.
                           Fed. Proc. 34:1835-1844.
                      Spyker, J.M., S.B. Sparber, and A.M.
                           Goldberg. 1972. Subtle conse-
                           quences of methylmercury expo-
                           sure: Behavioral deviations in
                           offspring of treated mothers.
                           Science 177:621-623.
                      Su, M.Q., and G.T. Okita.  1976. Behav-
                           ioral effects on the progeny of mice
                           treated with methylmercury. Toxi-
                           col. Appl. Pharmacol. 38:195-205.
Suter, K.E., and H. Schon. 1986. Testing
     strategies in behavioral teratology:
     I. Testing battery approach. Neruro-
     behav. Toxicol. Teratol. 8:561-566.
Vorhees, C. 1985. Behavioral effects of
     prenatal methylmercury in rats: a
     parallel trial to the collaborative
     behavioral teratology study.
     Neurobehav. Toxicol. Teratol.
Zenick, H.  1976. Evoked potential
     alterations in methylmercury
     chloride toxicity. Pharmacol.
     Biochem. Behav. 5:253-255.

   Conference Proceedings




                                                  BODY POSTURE
                                                  •TAIL  POSITION
                                                  HIND-LEG CROSSING
                                       'RIGHTING REFLEX
                                        STAYING ON  A  ROD
                                        HEAD  MAINTENANCE
                                                                RIGHTING REFLEX
                                                              STAYING  ON A ROD

                                                                 •RIGHTING REFLEX*
                                                              •TAIL POSITION
                                                            •HIND-LEG  PARALYSIS
                                                            LIMB POSTURE
                                                                                10/4 Hg/g DIET
                                                             29       36

                                                            EXPERIMENTAL DAY
                           Brain mercury  concentrations associated with the appearance of neuroloeical
                 symptoms m mice exposed  to methylmercury in the diet. Exposure stopped after da?4?fbr
                      death. (Reproduced with permission from Suzuki and Miyama (47).)
                                                                               Biel Maze
 - .   Soe«0 Trials
   Bitl Mazt

  Maz» Errors J
                Maze Times
I'! J
60 i-
~.n l-
-o -
30 <-
20 1-
10 -




100- IOOOH

60 1-















                                                                       6 r-



   Mean (±SE) swimming performance in a straight channel
.ml in a Biel maze summed across all test trials for errors
.  and maze time (right). **p<0,()t. '/>
               National Forum on Mercury in Fish
                     llHC-induced levninc deviations of prenatally treated mate (a) and female (b) nit: percent-
                 afc* of operant behavior performance in three different test session of toe instrumental conditioning
                 protram "differential reinforcement of hifh ntes" (DRH). The percental deviations from controls
                 (-10096) art listed underneath the columns. All data are expressed as group means. Verticil brackets
    NCTR battery (6 laboratories) -
       maternal weight gain
       physical landmarks
       negative geotaxls
       olfactory discrimination
       auditory startle habituation
       activity (1 and 23 hour)
       discrete trial visual
    Cincinnati battery
       physical landmarks
       surface righting
       negative geotaxls
       olfactory orientation
       swimming ontogeny
       complex water maze
no effect
no effect
 t high dose
 t adult
 i correct, high dose all labs combined
i high dose
no effect
no effect
no effect
minimal effect, high dose
Impaired, high dose

Conference Proceedings
                     COLLABORATIVE STUDIES
     physical landmarks
     visual discrimination, delayed
i  latency
4  no-response trials
no effect accuracy
     locomotor/exploratory behavior
     complex wheel
different pattern of alley entry
                                                 June 4. 1964
                                                ""July 10. 1968
                                                 July 31. 1969
                  Typical course of concentric constriction, which began with a unilateral deficit of the
              temporal crescent

                                         National Forum on Mercury in Fish
                                                     LEFT   EYE
                                             HO	1M
                                                                                               nONKEY  82
                             Visual field chart for the left eye of monkey 82 that shows how the boundary of
                     field was determined from the pattern of detections and misses. Tha origin of the polar
                     represents the center of gaze.




55 "
gj 80

Vj 70
^ 100

|ii 90




                                                        2   6  10  14  18  22  26 30

                                                    WEEKS SINCE METHYLMERCURY BEGAN

                                                          Effecti of a 29-wk exposure to
                                                  .uethyimercury on the viiual  Hivriminarion
                                                  of macaque *81. The doling procedure and
                                                  blood Hg concentrations ire shown in Fig. 7.
                                                  Testing of some luminances did not begin
                                                  until blood concentrations had stabilized.
                                                  Symbols are the same as in Fig. 8. The arrows
                                                  in the two upper graphs signify a decline to
                                                  33% correct (chance).  At the time of sacri-
                                                  fice in the 31st wk, the monkey had great dif-
                                                  ficulty in locating objects visually and finding
                                                  its way around the home cage. Motor inco-

                                                  to impairment of vision and touch

Conference Proceedings
                                    Object permanence apparatus.
                                      monitor   camera   computer
                                    -The apparatus and an example of die itimuli wed

National Forum on Mercury in Fish
                                                                      cnttlou. «K dnta tk> UmkoUt
                                                 SoUi kMl Of met dipt nrpmol cntioM o( UmlnUl fcr aanl
                                      JOCB9    40090       S     10000
                                                                                                    10000    20900    MOO    40000
                              XOOO    XGOD
                                                        0     10000   20000    30000

                  20000   WOO   40000
              Absolute detection threshold! (SPL (dB)) for control monkeys (top left) and each of five methyl mercury-treated monkeys. For treated
   monkeys. X represents the right ear and Q the left. For control monkeys, each symbol represent! an individual: • 06, 0 117, and A 120. Dashed lines
   represent the right ear, solid lines the left.

 Conference Proceedings
                         TABLE 1. Time to Complete Raisin Pick-up Test
                                                        Mean Time (sec)


                         Mathylmenury Exposed
finger broken
finger broken
                        Mann-Whfoiey U test P - 0.047 for each hand.
                         Comment: Missed raisins; usod more than 2 fingers.
TABLE2. InddenceofNoResponse-onSensoryAssessment (Assessor 1/Assessor2,
                                                     Total*    Prick Foot  FtfckHand
 Treated 35
 Control  02






                                                             National Forum on Mercury in Fish
       Exposure         nnse           Blood Ha                Effects
   Blood Hg
       In utero
       postnatal only
       (to 7 years)
       In utero plus
       (to 4 years)
  10.25. or 50
during Infancy
- retarded object permanence
- Impaired recognition memory
- changes In social behavior

during adulthood
- facilitated delayed alternation
- Impaired spatial vision

- Impaired spatial vision
- Impaired high frequency hearing
- impaired somatosensory function
(delayed neurotoxlcity)

during Infancy
- overt toxicity (one at high dose)
- no effect - discrimination reversal
- changes on schedule-controlled

 during juvenile-adulthood
 - Impaired spatial vision
 - Impaired somatosensory function

                    National Forum on
                       Mercury in Fish
   An Overview of Human Studies
   on CNS Effects of Methylmercury
  Roberta f . White
  Odense University, Department of Environmental Medicine

                         EnVJronmental ""»»* Center and Department of
  Philippe A. Grandjean
  Odense University, Department of Environmental Medicine
  Pal Weihe
  Department of Occupational and Environmental Health, Torshavn, Faroe Islands
        paper will review the classic
      literature on the central nervous
      system (CNS) effects of exposure
 to methylmercury, based largely on
 studies carried out on individuals
 exposed to mercury in Minamata and
 Iraq. We will then proceed to discuss
 some current epidemiologic studies
 designed to investigate the relationships
 between methylmercury exposure and
 measures of CNS function.

 Classic Studies:
 Neuropathological Findings

     The classic studies on the
 neuropathological effects of methylmer-
 cury intoxication have been well sum-
 marized for the Iraq and Minamata cases
 by Choi (1989). A more recent series of
 case descriptions involves a family from
 New Mexico (Davis et al., 1994).
 Basically, these cases demonstrate a
 relationship between age at exposure
and neuropathological outcome.
    Prenatal exposure. Individuals
  exposed to methylmercury in utero who
  subsequently develop clinical disease
  and who have undergone autopsy show
  widespread brain damage extending to
  the cerebral cortex and cerebellum with
  remarkable reduction in brain size and
  changes in the cytoarchitecture of the
  brain (Eto et al., 1992; Matsumo et al
     Childhood exposure. Children
 exposed to methylmercury who develop
 clinical disease and whose brains have
 been studied have shown significant
 neuropathological abnormalities in the
 cerebellum and cerebral cortex with
 widely distributed focal cerebral lesions
 and some reduction in brain size.
 However, brains were less reduced in
 size than those of children exposed
 prenatally and brain architecture  was not
 disturbed (Takeuchi et al., 1979).
    Adult exposure.  Brains of adults
 with clinical disease showed cerebellar
 changes, mild atrophy, and focal cortical
lesions at autopsy (Choi, 1989-
Takeuchi, 1968).

     Overview. The neuropathological
effects of methylmercury exposure of
sufficient severity to produce clinical
disease and/or death depend upon the
age of the affected individual at the time
of exposure.  In general, the younger the
exposed individual, the greater the
extent of neuropathological damage and
the greater the number of sites within
the brain that are affected (Choi, 1989;
Davis et al.,  1994).
 Classic Studies: Behavioral

      Like the neuropathological studies,
 the behavioral evidence from the Iraqi
 and New Mexico cases and from studies
 completed in New, Zealand suggests that
 the younger the individual at the time of
 exposure, the greater the impact on the
      Prenatal exposure. Prenatal
 exposure to methylmercury resulting in
 clinical disease is known to be associated
 with intellectual deficits in multiple
 cognitive domains. In addition, children
 prenatally exposed to methylmercury at
 levels insufficient to develop obvious
  disease might exhibit changes in general
  cognitive function on a delayed basis (i.e.,
  they might later show deficits that are not
  obvious at birth) (Marsh et al., 1980).
       Childhood exposure. Exposure to
  methylmercury in childhood both at
  levels sufficient to produce obvious
  disease and at lower levels is also
  associated with multiple cognitive
  deficits, which are also known to persist
  (Kjellstrom, 1986; WHO, 1990). It
  should be noted that childhood exposure
  effects can be difficult to distinguish
  from prenatal exposure effects due to
  prevalance of exposure in populations
   studied and persistence of mercury in
   the brain.
        Mult exposure. Exposure to
   methylmercury in adulthood can  produce
   a variety of deficits, which have been less
   intensively studied than those associated
   with childhood exposure but seem to
   include prominent visuospatial and motor
   impairment (Davis et al., 1994).
Current Studies

     Findings of functional deficits and
physical abnormalities from the
Minamata, Iraq, and New Mexico cases
reflect those seen largely in individuals
with obvious clinical disease who
demonstrate severe CNS damage. More
recent epidemiologic studies being
carried out by T. Clarkson and col-
leagues in the Seychelle Islands and our
group in the Faroe Islands focus on
exposure effects at the other end of the
health continuum, where subtle CNS
 effects might be occurring in the ab-
 sence of obvious clinical disease. These
 studies focus on questions such as the
     1. Does exposure to methylmercury
        at levels that are not associated
        with obvious clinical disease
        nonetheless produce target organ
        system  changes in the CNS that
        are subtle but measurable using
        sophisticated testing?
     2. What levels of exposure are
        required to produce behavioral
     3. What are the relationships
        between age at exposure, expres-
        sion of behavioral changes, and
        persistence of cognitive deficit?
        Do different kinds  of behavioral
        changes appear at different ages?
        The project in the Seychelle
  Islands, for which T. Clarkson is
  principal investigator, is a longitudinal
  study of children evaluated at 6, 19, and
  29 months of age who are now being
  retested at about age 5.5 years. Expo-
  sure measures include maternal hair
  levels of mercury during pregnancy and
  delivery and hair levels for the child at
  each testing date. Physical, neurologi-
  cal, and psychological examinations
  were completed at each evaluation.
   Results are pending  (G. Myers, personal

   Faroe Islands Study
        This investigation focuses on the
   relationship between prenatal exposure
   to methylmercury (Grandjean, 1993)

 Conference Proceedings
 and measures of CNS function 7 years
      Investigators are P. Grandjean,
 Principal Investigator; P. Weihe, Co-
 Principal Investigator; R.F. White and F.
 Debes, Neuropsychology; K. Murata, K.
 Yokoyama, F, Okajima, S. Araki,
 Neurophysiology; and N. Sorensen,
      Study subjects are about 1000
 children born between 1986 and 1987
 who were evaluated in 1993 and 1994
 (about age 7 at time of testing). Results
 presented in this paper reflect data
 collected in 1993 on children belonging
 to the oldest half of the cohort (N=443).
     Exposure measures included cord
 blood mercury levels (0-350 ug/1),
 maternal hair mercury levels (0-40 ug/
 g), maternal dietary histories during
 pregnancy, and PCB levels in umbilical
 cord (pending).
     Outcome measures used in the
 study included pediatric physical
 examination; functional neurological
 examination; electrophysiological
 measures (visual evoked potentials,
 brainstem-auditory evoked potentials,
 computerized posturography, and EGG
 R-R interval variability); and neuro-
psychological measures.
     The neuropsychological test
battery included the following tests:
   • Neurobehavioral Evaluation
      System (NES) Finger Tapping
   • NES Hand-Eye Coordination Test
   •  NES Continuous Performance
      Test (Child version)
   •  Wechsler Intelligence Scale for
      Children-Revised (WISC-R)-
      Digit Spans Forward
   Verbal reasoning:
   • WISC-R Similarities
   • Boston Naming Test
   •  WISC-R Block Designs
   •  Bender Gestalt Test
   •  Tactual Performance Test
   •  California Verbal Learning Test
  Exposure measures from the Year 1 data
  are summarized in Tables 1 and 2.
       Results.  The Year 1 data (N=443)
  suggest that some neurobehavioral
  dysfunction is related to maternal
  seafood intake during pregnancy,
  particularly on WISC-R Digit Spans
  Forward and the Boston Naming Test
  (see Tables 3 and 4). Though the
  medians for the tests are similar or
  identical, the upper exposure groups had
  many more instances of scores in. the
  lowest quartile. In addition to these
  results, positive findings were seen on
  the NES Continuous Performance Test
  (child version) for the standard devia-
  tions obtained for reaction time and the
 number of false-positive errors. These
 findings must be viewed with caution,
 however, because  residence in the
 capital area of Torshavn is associated
 with lower exposure levels and con-
 founder analysis has not yet been carried
 out.  Also, PCB exposure levels are
 being determined and could conceivably
 explain some of the associations seen,
 although mercury seems to be related to
 some of the test results.

     Classical studies of methylmercury
 effects on CNS structure and function in
 humans suggest that the extent and
 severity of deficits are greater the
Table 1. Maternal marine food intake during pregnancy


# whale dinners/mo
# fish dinners/wk
Note: Data incomplete for one case.

Table 2. Median mercury concentrations
Cord blood G-ig/1)
; 21.1
Maternal hair (jlg/g)

Table 3. WISC-R Digit Spans Forward
Number (%) less than 3
Note: Spearman's r=-0.13; p=0.007.

Table 4.  Boston Naming Test
Numb er (%) less than 23
 Note: Spearman's r=-0.11; p=0.02.
                       younger the individual is at the time of
                       exposure. Preliminary results from the
                       first year of data collection in our study
                       of children in the Faroe Islands suggest
                       that there is a relationship between
                       maternal intake of seafood during
                       pregnancy and CNS function in children
                       7 years later. However, these data
                       cannot be directly related to mercury
                       exposure until further investigation of
                       potential confounders has been com-

                       Choi, B.H. 1989.  The effects of methyl-
                            mercury on the developing brain.
                            Prog. Neurobiol. 32:447-470.
                       Davis, L.E., M. Hornfield, H.S.
                            Mooney, K.J. Fiedler, K.Y.
                            Haaland, W.W. Orrison, E.
                            Cemichieri, and T.W. Clarkson.
                             1994.  Methylmercury poisoning:
                            Long-term clinical radiological,
                            toxicological and pathological
                             studies of an affected family. Ann.
                            Neural. 35:680-688.
                       Eto, K., S. Oyanagi, Y. Itali, H.
                             Tokunagia, Y. Takizawa, and I.
                             Suda. 1992. A fetal type of
                                                                    National Forum on Mercury in Fish
     Minamata disease: An autopsy
     case report with special reference
     to the nervous system. Mol. Chem.
     Neuropathol. 16:171-186.
Grandjean, P. 1993. Neurobehavioral
     effects of intrauterine methylmer-
     cury exposure.  Proceedings of the
     International Symposium on
     Assessment of Environmental
     Pollution and Health Effects from
     Methylmercury. World Health
     Organization and National Institute
     for Minamata Disease.
Kjellstrom, T., P. Kennedy, S. Wassis,
     and C. Mantell. 1986. Physical
     and mental development of
     children with prenatal exposure to
     mercury from fish. Stage 1.
     Preliminary tests at age 4.  Report
     3080. National Swedish Environ-
     mental Protection Board,
Marsh,  D.O., GJ. Meyers, T.W.
     Clarkson, L. Amin-Zaki, S. Tikriti,
     andM.Majeed. 1980. Fetal
     methylmercury poisoning: Clini-
     cal and pathological features.  Ann.
     Neural. 7:348-353.
Matsumoto, H.,  G. Koya,  and T.
     Takeuchi.  1965.  Fetal Minamata
     -Disease: A neuropathological
     study of two cases of intrauterine
     intoxication by methyl mercury
     compound. J. Neuropathol. Exp.
     Neural. 24:563-574.
 Takeuchi, T.  1968.  Anthology of
     Minamata Disease.  In Minamata
     Disease Study Group of Minamata
     Disease, pp. 178-194. Kumamoto
      University Press, Japan.
 Takeuchi, T., N. Eto, and K. Eto. 1979.
      Neuropathology of childhood
      cases of methylmercury poisoning
      (Minamata Disease) with pro-
      longed symptoms, with particular
      reference to the decortication
      syndrome. Neurotoxicol. 1:1-20.
 WHO. 1990. Methylmercury.  Environ-
      mental Health Criteria.  World
      Health Organization, Geneva.

                   National Forum on
  Exposure Assessment  for
  Alan H. Stem
  Division of Science and Research, New Jersey Department of Environmental
  Protection,* Trenton, New Jersey
 What Questions Can Exposure
 Assessment Data for
 Methylmercuiy Answer?
      ie key questions to be answered
      include the following:
    •  To what extent is the (pregnant/
       fetal) population at risk?
       -  What is the distribution of
       -  What fraction of the popula-
         tion is at risk?
    •  What priority should be assigned
       to addressing methylmercury
    • What factors result in elevated
      -  Fish consumption factors
      -  Other biologic and demo-
        graphic factors
    •  Can the high-risk population be
      identified in a way that allows it
      to be  targeted for intervention?
      - Possible identifying variables:
        geography, race/ethnicity, SES
Estimation of Methylmercury
Exposure Based on National

    Daily intake of methylmercury can
be calculated as follows (Stern, 1993):
 This work does not necessarily reflect the policy or
 views of the New Jersey Department of Environmen-
 tal Protection.
      I = MxCTxFxA
  where I is the methylmercury intake
  (ug/day); M is the mass offish/
  seafood consumed per day (g/day); CT
  is the concentration of total mercury
  in fish (ug/g); F is the fraction of total
  mercury present as methylmercury;
  and A is fractional gastrointestinal
  absorption of methylmercury.
      Nearly all biological and human
  activity parameters occur as distribu-
  tions. In order for I to approximate
  the true population distribution of fish
 ingestion, input values must also be
 distributions.  Point value estimates
 (e.g., means), no matter how reliable,
 will not be useful in generating a
 distribution.  A Monte Carlo calcula-
 tion approach is required.

 Mass offish Consumed Per Day

     Few data are in distributional
 form. Data from Rupp et al. (1980)
 are extensive, but from 1973-74.
     Dietary habits have changed
 since then. EPA estimates a 62
 percent increase in consumption from
 1960 to 1986.
     The U.S. Food and Drug Ad-
 ministration's 14-day Menu Census
 Study results for consumers were as
    mean = 32 g/day
    90th percentile = 64 g/day
An underlying lognormal distribution



   , i
                      is assumed. The two resulting lognor-
                      mal distributions are averaged.

                      Concentration of Total Mercury
                      In Fish
                          This factor requires data on
                      concentration of mercury by species
                      weighted by consumption.  A high
                      concentration in a species that is
                      rarely consumed will have little
                           Only one comprehensive database,
                      the National Marine Fisheries Service's
                      1978 study (Hall et al., 1978), is avail-
                      able. The database includes concentra-
                      tion by percent of catch from U.S.
                      coastal waters intended for human
                      consumption. Catch for human con-
                      sumption estimates species distribution
                      in the average diet. This distribution is
                      illustrated in Figure 1. There are,
                      however, caveats for the use of this
                      database.  The data are only for U.S.
                      waters, and they reflect an average mix
                      of species hi the diet, not individual diet
                      variability hi species preference.

                      Fraction of Total Mercury Present
                      as Methylmercury
                           Earlier estimates (mean -70 per-
                      cent) apparently were influenced by
                      background inorganic mercury.
                      Current ultraclean estimates (Bloom,
                       1992) are available.  These data are
                    ©RISK Simulation
           .094 '   .188    .281    .375

        Total Hg Concentration in U.S. Catch for Human Consumption
  Figure 1. Distribution of mercury concentrations in the U.S. catch intended for human
                                                         National Forum on Mercury in Fish

                                                   modeled as a normal distribution with
                                                   a mean of 95 percent and a standard
                                                   deviation of 0.063 percent. This
                                                   reflects a truncated distribution to
                                                   eliminate observations with methyl-
                                                   mercury >100 percent.

                                                   Fractional ClAbsorption of
                                                        The fractional gastrointestinal
                                                    absorption of methylmercury is
                                                    assumed to be 90-100 percent. It was
                                                    -93 percent in rats fed fish with
                                                    intrinsic methylmercury (Yannei and
                                                    Sachs, 1993).

     The results of this Monte Carlo
simulation are presented graphically
in Figure 2.  Numerical results for
selected percentiles of the fish-
consuming population are as follows:

     mean = 3.7 ng/day
     50% < 1.5 ug/day
     75% < 3.7
     90% < 8.7
     95% < 15.4
     99% < 33,2
These new estimates do not distinguish
by sex and can be adjusted as follows:
USFDA 1980-82 Total Diet Study:
                     Women (25-30)
                     eat fish portions
                     62-95 percent the
                     size of those
                     eaten by men.
                     estimates for
                     women of
                     childbearing age
                     can be reduced
                     by -20 percent.
                          The rela-
                     tionship of
                     adjusted exposure
                     estimates of daily
                     intake to possible
                     reference dose
                      guidance is shown
                                        Sampling=Latin Hypercube "J_
.563    .656
                                                                          in Table 1. The

  Conference Proceedings
  margin of protectiveness. Therefore, this
  comparison does not reflect the risk of
  actual adverse effects, but an expression of
  the estimated exposure relative toamargin
  of safety. Given the quantitative uncertain-
  ties in the model inputs, model predictions
  should be viewed only as qualitative
  predictions of exposures. When intake is
  computed to an estimated threshold for
  developmental affects (rather than a
  reference dose with its attendant margin of
  safety), less than 1 percent of women of
  childbearing age are estimated to exceed an
  estimated thresholdfor developmental
  effects (-40 jug/day).

 Ideal Characteristics of State/
 Regional Exposure

      Ideal characteristics of state/
 regional exposure assessments include:

     •  Direct measurement of methyl-
       mercury biomarkers (hair, blood)
       rather than estimates of food
    •  Speciation of mercury in
       biological samples; contribution
       of dental amalgams to total
    •  Large sample size; adequate
       representation of tail of the
            <>   3.125 6.25  8.375  1s7 15.625 18.75 21.875  25
           Estimated Dally Mathylmerewy Int.*. for All U.S. Fiih Consum.rs

                  A. Frequency distribution.
           0  3.125  6.25  9.875  12.3 15.625 18.75 21.875  25
         Estimated Daily MrtiyliMteuiy Intak. for All U.S. Hth Consum.rj

           B. Cumulative probability distribution.
Figure 2. Estimating daily intake of methylmercury among U.S.
fish consumers.
      Cross-sectional population
      sample.  Currently, there is
      insufficient information to
      permit oversampling of "high-
      risk population."
Table 1.  Relationship of adjusted estimates to reference dose guidance
Max consumers
Intake exceeding
	 	 (ug/day) maxintake
RfD 21 -w
, , *L 3%
based on
(0.3 ng/kg/day)
based on
(0.07 ug/kg/day)
max consumers
intake exceeding
(ug/day) maxintake
19 3%

4 18%

                                                                   National Forum on Mercury in Fish
                            Characterization of population
                            relative to fish consumption;
                            species, frequency, portion size.
                            Characterization of other demo-
                            graphic/lifestyle variables to
                            provide functional description of
                            high-risk population.
                            Sampling early in pregnancy
                            (first trimester) to avoid con-
                            founding due to pregnancy
                            related changes in physiology and

                      Bloom, N.S. 1992. On the chemical
                           form of mercury in edible fish and
                           marine invertebrate tissue.  Can. J.
                           FishAquat.Sd.  49:1010-1017.
                      Hall, R.A., E.G. Zook, and G.M.
                           Meaburn. 1978. National Marine
    Fisheries Service survey of trace
    elements in the fishery resource.
    NOAA Technical Report NMFS
    SSRF-721. U.S. Department of
    Commerce, National Oceanic and
    Atmospheric Administration,
    National Marine Fisheries Service.
Rupp, E.M., F.L. Miller, and C.F. Baes.
     1980. Some results of recent
     surveys of fish and shellfish
     consumption by age and region of
     U.S. Residents. Health Phys.
Stern, A.H. 1993.  Re-evaluation of the
     reference dose for methylmercury
     and assessment of current exposure
     levels. Risk Anal. 13:355-364.
Yannai, S., and K.M. Sachs. 1993.
     Absorption and accumulation of
     cadmium, lead and mercury from
     foods by rats. Food Chem. Tox.

                   National Forum on
                      Mercury in Fish
  Methylmercury  (MeHg) - Hazard
  and Risk
  Michael Bolger
  U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition
  Contaminants Branch, Washington, DC
 Environmental Occurrence
 and Exposure

         Mercury (Hg) in the environ-
         ment arises from both natural
         and man-made sources, and
 the global movement of mercury almost
 exclusively involves the inorganic
 forms, as shown in Figure 1 (IPCS/
 WHO, 1990). It is estimated that
 approximately 2700-6000 tons of
 elemental mercury are released naturally
 into the atmosphere by degassing from
 the earth's crust and oceans. Human
 activities, primarily the combustion of
 fossil fuels and industrial production,
 account for the release of 2000-3000
 tons of mercury into the atmosphere.
 However, these forms do not generally
 accumulate in food. It is the conversion
 of inorganic mercury to the methylated
 form in the aquatic ecosystem that is of
 critical importance in terms of the
 presence of mercury in food.
     With regard to environmental
 transport, mercury (or more specifically
 mercury vapor) is a highly mobile
 metal. Mercury deposited on land or
 water is in part re-emitted into the
 atmosphere, and the bottom sediment of
 the oceans and bodies of fresh water are
 the ultimate sinks in which inorganic
 mercury is deposited as the highly
insoluble mercury sulfide. The methyla-
tion of inorganic mercury, which takes
place via both nonenzymatic and
 enzymatic pathways, occurs primarily in
 freshwater and marine sediments, as
 well as in the water columns of these
 bodies of water, as a result of microbial
 activity. Methylmercury (MeHg) Is
 enriched to a high degree in aquatic
 food, with the highest levels occurring
 in predatory  fishes, particularly those at
 the top of the aquatic food chain. While
 methylmercury is also incorporated in
 the terrestrial environment, enrichment
 does not occur to the same extent in the
 terrestrial food chain. As shown in. Table
 1, methylmercury in fish and fish
 products is the predominant source of
 methylmercury exposure. The estimate
 of methylmercury exposure of 2.4 fig/
         The   Global   Cycle  of  Mercury
                 (2  x 10'12  g/l)
                                      (2  x  10'9  g/|)
      (20 x  10'6  g/kg)
(2  x  10'9 g/|)
                 BOTTOM SEDIMENT
                 (20 x ID'8 g/kg)    HgS
Figure 1. The global cycle of mercury.

                                                                     National Forum on Mercury in Fish
Table 1. Intake of mercury (u,g/day)a in absence of
Exposure Source
Other Food
Drinking Water
Dental Amalgams
Elemental Hg
Inorganic Hg
 intake, and second is amount retained in body (IPCS/WHO, 1990).

                       day is an estimate for the general
                       population. According to a 1982-87
                       survey by the Market Research Corpora-
                       tion of America (MRCA), about 77
                       percent of the U.S. population are
                       considered to be fish eaters. Thus, of an
                       estimated population of 250 million in
                       1990,192 million people ate fish or
                       seafood on a somewhat regular basis.
                       The 14-day consumption values from
                       the survey are 32 g/day for the mean and
                       64 g/day for the 90th percentile.  The
                       frequency of the surveyed population
                       who reported shellfish eating was 13
                       percent for crustaceans and 4.8 percent
                       for molluscs. Using standard portion
                       sizes (USDA, n.d.), the estimated mean
                       and 90th percentile daily intakes varied
                       from 4 to 18 g for molluscs and from 9
                       to 19 g for crustaceans. The estimated
                       intakes of methylmercury resulting from
                       consumption offish containing an
                       average level of 0.3 ppm mercury
                       (NMFS, 1978) would vary from

  Table 2. Mercury (ppm) in a variety of finfish and shellfish"
  Orange Roughy
  Perch (freshwater)
                                           0.10 - 0.31
                                            ND - 0.08
                                           0.01 - 0.14
                                           0.10 - 0.23
                                           0.42 - 0.71
                                            ND - 0.31
                                            ND - 0.10
                                           0.23 - 2.95
                                           0.26 - 3.22
  • Summary of FDA analysis of mercury levels in species of fish and shellfish.
day (mean) to 19/ig/day (90th percen-
tile). A consumption study (National
Fisheries Institute, 1987) reported that
81 percent of the population eat tuna at
least once in a year, while shrimp, in
second place, is consumed by 38 percent
of the population.
     As shown in Table 2, mercury can
be found in many finfish and shellfish
with mean levels generally below 0.3 ppm
and methylmercury generally comprising
90-100 percent of total mercury.  Al-
though many species contain low levels of
methylmercury, long-lived, predatory fish
(e.g., swordfish) tend to have higher
levels (i.e., greater than 1 ppm). As a
result, the FDA published a consumption
advisory for women of child-bearing age
that recommended the reduced consump-
tion of species that routinely have elevated
levels of methylmercury.
 Toxicokinetics and Toxicity

      Methylmercury in the human diet
 is almost completely absorbed into the
 bloodstream. Age, including the neona-
 tal stage, has little effect on gastrointes-
 tinal absorption, which is usually more
 than 90 percent of oral intake. Once
 absorbed, methylmercury is bound to
 sulfhydryl and disulfide groups of large
 molecules, particularly those of proteins
 hi the plasma and hemoglobin hi the red
 blood cells, and is widely distributed to
 all organs and tissues. Equilibration
 between blood and organs and tissues
 occurs in about 4 days. Organs  that
 accumulate and concentrate methylmer-
 cury include the brain, liver,  and
 kidneys. Distribution of methylmercury
 to the fetal and adult brain is somewhat
 preferential, with about 10 percent of
 the body burden localized in the central
 nervous system. The concentration in
 the brain is roughly six times that found
 in the blood. Methylmercury readily
 crosses the placenta, causing cord blood
 levels to be somewhat higher than
  maternal levels. The mercury concentra-
  tion of human breast milk varies, but is
  approximately 5 percent of the maternal
  serum mercury concentration.

    Conference Proceedings
        The demethylation of methylmer-
   cury appears to occur in all tissues and
   is an initial step in the excretion of
   methylmercury. In humans the biologi-
   cal half-life is approximately 70 days,
   with the removal of mercury occurring
   more slowly from the central nervous
   system than from other tissues. The
   primary route of excretion occurs
   through the feces. The accumulation of
   methylmercury in humans is best
   measured by residues in hair and blood.
   The concentrations in hair are propor-
   tional to blood concentrations at the
   time of formation of the hair strand. The
   blood-to-hair ratio in humans is gener-
   ally about 1 to 250. Once incorporated
   into the hair strand, its concentration
   remains unchanged and  serves as a
   biomarker of exposure that can be
   recapitulated over time.
       The toxicokinetics of methylmer-
  cury are best described by a single-
  compartment model in which a 70-day
  half-life predicts that whole-body steady
  state is achieved in about one year. The
  relationship between the average daily
  dietary intake and the steady-state
  mercury concentration (C) in the blood
  is described by the equation C (blood) =
  0.95 x mercury (diet). A number .of
  population studies of blood and hair
  mercury levels have noted a fair amount
  of overlap in these populations, and the
  overlap includes those levels reported
  for  "fish-eating" vs."non-fish-eating"
 populations. Many questions remain
 concerning the interaction between
 methylrnercury and essential dietary
 nutrients, especially selenium. Some
 studies have shown that selenium
 ameliorates the adverse effects of
 methylmercury, whereas others have
 been less conclusive. The delineation of
 the role of essential elements, such as
 selenium, in the expression of the
 toxicity of methylmercury is particu-
 larly important because of the concomi-
 tant  exposure of methylmercury and
 essential elements, like selenium, in a
 fish-eating population.
     The nervous system is the primary
target tissue for the toxic effects of
methylmercury. The sensory, visual,
    and auditory functions and those areas
    concerned with coordination, especially
    the cerebellum, are the most affected.
    Symptoms associated with methylmer-
    cury in humans (Minimata and NMgata,
    Japan and Iraq), include paresthesia,
    malaise, blurred vision, concentric
    constriction of the visual field, deaf-
    ness, dysarthria, and ataxia. Methylm-
   ercury poisoning has several important
   features: (1) a long latent period lasting
   several months; (2) damage limited to
   the central nervous system; (3) highly
   localized damage (e.g., visual cortex
   and the granular layers of the cerebel-
   lum); (4) irreversible effects in severe
   cases, resulting from destruction of
   neuronal cells; and (5) nonspecific
   subjective early complaints, such as
   paresthesia, blurred vision,  and malaise.
   The most sensitive neurological re-
   sponse in adults, paresthesia, occurred
   at an estimated hair mercury concentra-
  tion of 50 ppm and a whole blood
  concentration of 200 ppb. These levels
  were attained with a minimum steady-
  state, daily dietary methylmercury
  intake of 300' jug.
      During prenatal life and infancy,
  humans are susceptible to the toxic
  effects of methylmercury because of the
  sensitivity of the developing nervous
  system. Methylmercury has inhibitory
  effects on neuronal migration and cell
  division, which result in a deranged
  central nervous system cytoarchitecture
  and ectopic neurons. Methylmercury
 crosses the placenta, and concentrations
 in fetal red blood cells can be 30
 percent higher than in those of the
 mother. The effects of methylmercury
 poisoning on the developing infant are
 dose-dependent. Infants exposed to
 high  levels of methylmercury (e.g.,
 maternal hair levels > 70 ppm) develop
 cerebral palsy. Microcephaly,
 hyperreflexia, and gross motor and
 mental impairment, sometimes associ-
 ated with blindness or deafness, are the
 usual symptoms. Infants exposed to
 lower levels did not develop overt
 symptoms within the first few months
 of life, but later displayed symptoms of
psychomotor impairment and persis-

                      tence of pathological reflexes. Postmor-
                      tem observations indicate that damage
                      in prenatal exposure was generalized
                      throughout the brain in contrast to adult
                      exposure, where focal lesions were
                            The tolerable daily intake (TDI)
                      for methylmercury is 30 fig/day
                      (weekly intake, 210 ^g). This is based
                      on a daily effect level of 300 fig/day,
                      which corresponds with the lowest
                       observed effect level in the adult
                      nervous system, paresthesia, and the
                      use of a 10-fold uncertainty factor. The
                       FDA's original action level of 0.5 ppm
                       was based on preliminary information
                       from the Japanese episodes and con-
                       sumption and exposure information
                       available at the time (1960s and early
                       1970s). The action level was subse-
                       quently reaffirmed by several expert
                       study groups, and in 1974 the FDA
                       proposed to establish the action level by
                       formal rulemaking. In 1979 this pro-
                       posal was withdrawn because of newer
                       information which showed that the
                       lowest dose associated with effects in
                       adults was greater than originally
                       estimated and methylmercury exposure
                        was lower.
                             Figure  2 is a graphical depiction
                        of the effects noted in children exposed
               Methylmercury   in   Iraq:   Effect   on  CMS
                                          50     150   400
                       MATERNAL  HAIR -CQN.C.  (Hfl, JJBffl)
   Figure 2. Methylmercury in Iraq: effect on CNS.
      National Forum on Mercury in Fish

in utero in the poisoning episode in Iraq
(Cox et al., 1989). On the basis of this
study, a "practical threshold" of 10-20
ppm was identified for the effect of
methylmercury on the fetus. Several
important points must be made regard-
ing this study. First, the number of
mother-infant pairs was fairly small, 84
mother-infant pairs. Second, most of
the mothers whose offspring were
observed to have decrements in nervous
system function had body burdens that
exceeded the lowest effect level for
adults (50 ppm mercury hair). Third,
the background incidence of either
delayed  walking or CNS symptoms in a
population has a considerable impact on
the practical threshold for methylmer-
cury-induced effects. For example, if the
 estimate of the background occurrence
 of delayed walking is not 4 percent, but
 rather 8 percent, then the "practical
 threshold" is 119 ppm mercury hair
 level. This would result in a correspond-
 ing 10-fold increase in a TDI or refer-
 ence dose (RfD) derived on the basis of
 a 10-ppm hair mercury level.
       The major flaw of the TDI or RfD
  approach is that it is essentially an
  attempt to identify a level of exposure
  that is "safe" or "of negligible" risk. It
  does  not quantify what the risk is. It is a
                  qualitative description
                  of the risk that allows
                  us to conclude that an
                  exposure to a contami-
                  nant is not a problem.
                  With a contaminant
                  like methylmercury,
                  the answer we invari-
                  ably get from this
                  approach is that the
                  consumption of a
                  particular fish is
                  "unsafe" or the
                  population who
                  consumes it is "at
                  risk." The difficulty
                   with this answer is that
                   we do not know how
                   much of a problem a
                   particular exposure
                   represents. The TDI/
                   RfD approach should

 Conference Proceedings
 be the first step in an iterative process
 that leads us to ask the question "what is
 the level of risk." What is needed with
 methylmercury is a quantitative estima-
 tion of the variability in critical factors
 like fish consumption, methylmercury
 body burdens, rates of absorption, and
 target organ sensitivity, so that we
 derive ranges of risk and a quantitative
 description of the uncertainty of our risk
 levels. We should not ask the TDI/RfD
 methodology to do something it was not
 designed to  do and can never do, namely
 quantify risk.
     The following conclusions can be
 drawn regarding the potential hazard or
 risk of methylmercury in fish and
 shellfish. First, there is little demon-
 strable risk to the general population
 from methylmercury exposure through
 the consumption of fish and shellfish.
 Second, a certain segment of the popula-
 tion who consume large amounts of fish
 that contain  methylmercury may attain
 body burdens (e.g., mercury hair - 50
 ppm) associated with a low risk of
 neurological deficits in adults. Third,
 the developing nervous system of the
 fetus may be particularly sensitive to the
 adverse effects of methylmercury.
However, pronounced neurological
damage has been reported only in the
offspring of  women whose hair mercury
levels exceeded 70 ppm. Fourth, limited
evidence suggests that maternal hair
levels in the  range of 10-20 ppm are
 associated with subclinical neurological
 effects (e.g., delayed walking and
 central nervous system symptoms) in
 their offspring. Finally, it is imperative
 that these preliminary observations be
 confirmed in well-designed and con-
 ducted epidemiological studies of
 children from a fish-eating population
 and that a quantitative risk analysis that
 quantitatively describes the risk associ-
 ated with different levels of methylmer-
 cury exposure be conducted.

Cox et al. 1989.  Environ. Res. 49:318-
Food and Drug Administration (FDA).
     1979. Fed. Reg. 44:3990-3993.
Food and Drug Administration (FDA).
     1994. FDA Consumer, Sept.:5-8.
National Fisheries Institute. 1987. Fish
     consumption study.
NMFS.  1978. National Marine Fisher-
     ies Service survey of trade ele-
     ments in the fishery resource.
     NOAA Technical Report NMFS
     SSRF-721.  National Marine
     Fisheries Service.
USDA. n.d.  1987-88 national food con-
     sumption survey. U.S. Department
     of Agriculture, Washington, DC.
WHO. 1990. Environmental Health
     Criteria No. 101. World Health


                   National Forum on
                      Mercury in Fish
  An Approach  for Noncancer Risk
  Assessment  of Methylmercury
  John Clcmanec
  U.S. Environmental Protection Agency, Office of Research and Development,
  Cincinnati, Ohio
         Msrcury is a significant pollutant
         to which humans and animals
         can be exposed via the environ-
 ment. The most likely avenue of exposure
 for humans is through consumption offish
 that are contaminated with methylmercury
      A fairly extensive data base exists
 for methylmercury, both for animal
 species exposed within a laboratory
 setting and for humans exposed through
 accidental environmental contamina-
 tion. In both settings, the neurological
 effects on infants who have been
 exposed in utero are the most critical
 adverse effects.
     Traditionally, the two most difficult
 decisions to be made in noncancer risk
 assessment are (1) to define the single,
 most sensitive critical adverse effect and
 (2) to define the dose level for which no
 effect is seen (NOAEL) and the lowest
 observed adverse effect level (LOAEL).
 If extensive human data are available, the
 choice is usually made to base the risk
 assessment on human data rather than on
 animal studies. However, this decision
 usually presents two additional challenges
 to the risk assessor: accidental exposure
 of humans presents complications in
 quantifying the dose level and complica-
 tions that occur because of concurrent
 exposure to other toxic agents.
     Beginning in March 1993, the U.S.
Environmental Protection Agency
Interagency RfD/RfC Work Group
undertook the task of providing a quanti-
tative, noncancer assessment for meth-
 ylmercury. Initial screening of the data
 base narrowed the selection of a "critical
 study" to two possible choices. The first
 option was to use data from Iraq, collected
 in 1971-72 following human exposure to
 mercury-contaminated seed grain. The
 second choice was to use data by
 Kjellstrom et al. (1986,1989) for meth-
 ylmercury exposure for children of
 mothers in New Zealand who frequently
 consume fish. The New Zealand data
 were not used because the Agency felt
 that the psychological and developmental
 tests that had been chosen for evaluation
 were inappropriate for the effects of
     The principal quantitative data
 available for the Iraqi outbreak are from
 the summary of 84 mother-infant pairs
 provided in Marsh et al. (1989).  To
 establish a daily dose of methylmercury
 that the mothers received, a daily dose
 must be calculated indirectly from hair
 concentrations of the mothers. This hair
 concentration value is then converted to
 a corresponding blood level, which is
 then used to derive the daily oral
 consumption dose. A number of
 literature references are available to
 calculate these conversion factors.
 However, there is  a range of normal
 variation related to each of the conver-
 sions that, through use of the formula,
 results in greater variation than is
     The exposure data for the Iraqi
population  are presented in a continuous
fashion (as opposed to distinct dose

                                                                   National Forum on Mercury in Fish
                     groups resulting from animal studies)
                     with hair mercury concentrations
                     ranging from 0 to 674 ppm. To properly
                     evaluate these data, the use of a "bench-
                     mark dose" approach might prove to be
                     more useful than standard NOAEL-
                     LOAEL methodology.
                          It is likely that derivation of an
                     RfD for methylmercury based on devel-
                     opmental effects would be even more
                     conservative than the present value in
                     IRIS (1995) for adult effects of
                     paresthesia.  Once a new RfD is de-
                     rived, it is important that a mechanism
                     be put in place to quickly accommodate
                     the new human data from the Seychelle
                     Islands and Faroe Islands studies as they
                     become available.

                      Kjellstrom, T., P. Kennedy, S. Wallis,
                           and C. Mantel. 1986. Physical
                           and mental development of chil-
                           dren with prenatal exposure to
     mercury from fish. Stage 1:
     Preliminary test at age 4. National
     Swedish Environmental Protection
     Board, Report 3080, Solna,
Kjellstrom, T., P. Kennedy, S. Wallis,
     and C. Mantel. 1989. Physical
     and mental development of chil-
     dren with prenatal exposure to
     mercury from fish. Stage 2:
     Interviews and psychological test
     at age 6. National Swedish
     Environmental Protection Board,
     Report 3080, Solna, Sweden.
Marsh, D.O., T.W. Clarkson, C. Cox, et
     al.  1987. Fetal methylmercury
     poisoning: Relationship between
     concentration in single strands of
     maternal hair and child effects.
     Arch. Neural. 44:1017-1022.
USEPA. 1995.   Integrated Risk Infor-
     mation System (IRIS). U.S.
     Environmental Protection Agency.
     Office of Research and Develop-
     ment, Environmental Criteria and
     Assessment Office, Cincinnati,

Conference Proceedings
              A Reference Dose for Methytaiercury

                Sources of Reduced Uncertainty

1. The critical study was performed in humans.
2. The critical study identified the sensitive subpopulation.
3. The data base is fairly extensive except for the lack of a two-
   generation reproductive study.
4. Animal studies are generally supportive of the results in hu-


                  National Forum on
   Day Two: September 28, 1994^
                     Mercury in Fish
  Questions  and
  Session One
        After each speaker's presentation,
        an opportunity for questions and
        answers was provided. Time
 was also allotted for group discussions/
 question-and-answer sessions.
 Mercury Toxicity: An

 Dr. Thomas Clarkson, University of

 Q (Bruce Mintz, U.S. EPA, Headquar-
 ters): You mentioned the importance of
 glutathione in the excretion of methyl-
 mercury. In the Iraq population, could
 protein deficiencies have affected their
 ability to excrete methylmercury and
 made them more susceptible?

 Dr. Clarkson:
     There's no evidence of a pro-
 longed half-time, although the half-
 times in Iraq did cover a wide range.
 The diet in Iraq was mainly cereal,
 mainly bread, which is why they got
 poisoned. Their diets are low in protein.
 In general, we did not see starvation, but
 no one conducted a detailed dietary
 survey of this primitive countryside
population.  There were a lot of disease
and a lot of parasites in this population.
It is not an average population for sure.
I can't answer your question on glu-
tathione, but certainly a carbohydrate
 diet does not promote a high glutathione
 Q (Pom Shubat, Minnesota Department of
 Health): Regarding the microflora you
 discussed, does absence of microflora in
 the fetus and then the infant help explain
 the higher levels that are assumed to be
 present in the developing fetus and then
 the infant?

 Dr. Clarkson:

     They may. The system I described
 for excretion was for adult animals. An
 interesting phenomenon is that, in the
 suckling animal, the glutathione secre-
 tion does not occur. The secretion of
 glutathione from the liver into bile starts
 at the end of the suckling period. As a
 result, methylmercury itself is not
 excreted into bile in suckling animals.
 So even if there were microorganisms in
 the GI tract to break it down, it might
 not even get there. We are trying to
 check this by collecting hair samples in
 infants about 6 months of age and
 measuring the rate of decline in the hair
 samples month by month. We have
 enough children that are bottle fed so
 they're not exposed to methylmercury
 after birth. Right now we're having a
 hard time determining the rate of growth
 of hair in infants, and this is holding up
 the study. If anyone has any informa-
tion on the rate of growth of hair in
infants, I would be grateful to know.

                                                                  National Forum on Mercury in Fish
                     An Overview of Animal

                     Dr. Deborah Rice, Health Canada

                     No questions

                     An Overview of Human

                     Dr. Roberta White, Boston University

                     Q (Deborah Rice, Health Canada):  Are
                     you planning any functional testing of
                     sensory systems?

                     Dr. White:
                     Group Discussion/Question'
                          ' Answer Session
                      Q (Mike Bolger, U.S. Food and Drug
                      Administration): Regarding the results
                      of exposure analysis, it was my under-
                      standing that the primary methylmer-
                      cury exposure was coming from the
                      consumption of whale meat.  In terms of
                      meat consumption and total methylmer-
                      cury exposure, is more coming from the
                      consumption of whale meat than from
                      consumption offish?

                      Dr. White:
                          Both fish and whale. Regarding
                      PCBs, meat has lower levels and blub-
                      ber has higher levels. Regarding smok-
                      ing and alcohol consumption, alcohol
                      affects toxicokinetics in breast milk.

                      Q (Luanne Williams, North Carolina
                      Department of Environmental Health
                      and Natural Resources): At public
                      meetings I've encountered questions
                      from people concerning fish consump-
                      tion by their cats. Do you have any
                      advice for how to respond?

                      Dr. Clarkson:
                           I know of studies in which cats
                      were fed pike with varying levels of
methylmercury. At high doses they
were severely affected.

Q (Alan Stern, New Jersey Department
of Environmental Protection): Regard-
ing the applicability of your findings...

Dr. Rice:
     I try to make a point about rodent
literature that most has been aimed at
validating test batteries.  No one has
pursued observations to interpret the
effects of methylmercury in the rodent.

Q: What is the relationship between
maternal hair and fetal brain levels?

Dr. Clarkson:
     That is a good question.  We are
attempting to answer it by measuring
brain levels in autopsy cases.

Q (Pam Shubat, Minnesota Department
of Health): What human age is compa-
rable to a 13- to 14-year-old monkey?

Dr. Rice:
      A middle-aged, 40- to 50-year-old

Q (Pam Shubat, Minnesota Department
of Health): Are there currently plans
for the Faroe Islands to look at geriat-

Dr. White:
      People have always been exposed.
There are 50,000 people in the Faroe
Islands. It's a good place to look at
diagnostic outcomes.

 Q (Jerry Pollock, California EPA):  Is it
 true that the younger you are, the
greater the effects?

Dr.  White:

 Q (Bruce Mintz, U.S. EPA, Headquar-
 ters): Factoring in meals per month, is
 there any information that would tell us
 anything about a single exposure in one

 Conference Proceedings
 day that may be more or less significant
 in terms of brain levels and potential

 Dr. Clarkson:
     We found in Iraq that maximum
 brain level of methylmercury was the
 best predictor of effects. The fact that
 methylmercury is an irreversible poison
 indicated that the maximum level is
 very important.

 Q (Tom Burbacher, University of Wash-
 ington): Are you going to speciate?

 Dr. Clarkson:

 Q (Tom, Burbacher,  University of
 Washington): Are you going to look at
 different areas of the brain and follow
 up with kids?

 Dr. Clarkson:
     Infants who have died within a few
 weeks are all we've looked at.

 Dr. White:
     We'll follow up pending funding.

 Q (Mike Bolger, U.S. Food and Drug
Administration): Regarding dental
amalgam, these kids don't have amal-
gams, do they?

Dr. White:
     This is not seen as a problem.

Q (Mike Bolger, U.S. Food and Drug
Administration): Is there a connection
between dental amalgams and exposure
to different forms of mercury?

Dr. Clarkson:
     It's an interesting question.  There
was a study in rats or mice, in which
someone exposed one group to meth-
ylmercury, one group inhaled mercury
vapor, and one group was exposed to
both. There was another study in
which primates were given mercury
vapor.  He found the same results,
 more or less, with mercury vapor as
 with inorganic.

 Q (John Cicmanec, U.S. EPA): With
 regard to the Faroe Islands study,
 exposure during gestation is not con-
 stant.  Can you break it down between

 Dr. White:
     We do have dietary data. We don't
 know if it's possible to have accurate
 enough data. We can look at hair, and
 hair tells you when the exposure was.

 Q (Alan Stern, New Jersey Department
 of Environmental Protection): Regard-
 ing the effects of post-natal exposure,
 what are the sources of data to draw a
 conclusion of post-natal exposure
 independent of pre-natal exposure?

 Dr.  Clarkson:
     I don't know of any dose-response
 data. I am reluctant to draw any conclu-
 sions from lead experience.

 Q (Alan Stern, New Jersey Department
 of Environmental Protection): Regard-
 ing animal studies, are there studies on
post-natal exposure?

 Dr. Rice:
     Data are lacking.
Exposure Assessment for

Dr. Alan Stern, New Jersey Depart-
ment of Environmental Protection

Q (Arnold Kuzmack, U.S. EPA, Head-
quarters): One of the areas in which a
Monte Carlo analysis can go astray is if
your variables are not independent. In
particular with this case,  it could well
be that the people who eat a lot offish
are a different population from the
average.  They may eat different parts of
the fish, eat different species offish, and
get them from different places.  [Such
differences] could lead to significant

                                              National Forum on Mercury in Fish
**... there is a tremendous dif-
ference among different species
for mercury bioaccumulation as
well as age and size."
 differences in what the [statistical] tails
 look like. There should be some way to
 tease it out of surveys.

 Dr. Stern:
     I'm well aware of the problem you
 describe, although I don't think that in
 this case it has to do with correlations
 within the analysis itself. I think the
 problem arises with the data set we have
 from the National Marine Fisheries.
 The NMFS data which is reflective at
                       best of the
,^_____^^___   average
                       of the popula-
                       tion and the
                       consumers are
                       not likely to be
————^————   averaged in.
                       They probably
 have very different characteristics from
 the people in the middle of the curve.

 Q (Bruce Mintz, U.S. EPA, Headquar-
 ters):  Have you thought about looking
 at the exposure to children, and if so,
 how would you handle the body weight
 and consumption rate variables?

 Dr. Stern:
     I haven't given it much thought
 because there are no data. But the data
 that exist from the diet studies would
 probably be the only data that are
 relevant to children and those aren't
 distributional. There's really no way to
 get a handle on it.  An exposure study
 using biomarkers could be done with
 children, and it could follow the same
 parameters as for adults. That would be
 an interesting thing to do.

 Q (Russell Isaac, Massachusetts Depart-
 ment of Environmental Protection):
 Your concentration distribution was for
 marine fish from coastal waters rather
 than any freshwater fish?

 Dr. Stern:
        Yes, coastal marine fish.  For
 the general population, that's going to
be the great majority of fish consump-
tion.  These data at very best are for the
population average and don't tell us
anything about the subgroups in the

Q (Bill Hartley, Tulane Medical Cen-
ter):  From an exposure standpoint, can
you comment on how important you
think a creel survey approach would be,
looking at what fish are actually  caught
for each population? Because, as we
all know, there is a tremendous differ-
ence among different species for mer-
cury bioaccumulation as well as age
and size.

Dr. Stern:

     I attended the International
Society of Exposure Analysis/Interna-
tional Society of Environmental
Epidemiology joint conference  last
week in North Carolina, and there was
a paper presented there about the
discordance between creel surveys and
actual consumption. Apparently,
fishermen don't tell the truth about
what they catch, or they don't tell the
truth about what they eat from what
they catch.  So, I would be a little
concerned about the reliability of creel
surveys. If that's the best data  you
have, then go with it but realize there
will probably be some nonsystematic
sources of error in there.

Lee Weddig, National Fisheries Insti-
tute:  I express caution about using the
data on the mercury levels in coastal
species to indicate the amount of mer-
cury in the total supply. You mentioned
the impact of imports and in fact the
consumption of commercial species in
the United States is roughly 70 percent
imported product. We export fully 30-
40 percent of what we catch ourselves.
The actual U.S. supply is predominantly
imported species, and so the levels in
the coastal survey done in the 1970s are
really not representative of what is in
the marketplace. Changes in composi-
tion can also have a profound effect on
it. For example, a level is indicated for

 Conference Proceedings
 pollock. Back in the 1970s the pollock
 available was Atlantic pollock, and
 now the pollock that is in the market-
 place is Alaska pollock. With 25
 percent of the total catch being that
 one species, it -will have a profound
 effect on the total intakes you may
 come up with.

 Dr. Stern:
     I agree that new data would
 certainly be in order.

 FDA Perspective

 Dr. Mike Bolger, U.S. Food and Drug

 Q: I've had 2 years' experience
 dealing with mercury contamination
 levels in Louisiana, and I recognize
 that FDA and EPA and other scientists
 understand the complexities of doing
 an assessment when you 've got a site-
 specific contamination problem. But
 generally speaking we 've based our
 advisories on the issue of critical
 threshold for developmental. That
 [value of] 0.07 micrograms per
 kilogram per day is roughly what we
 use. What that results in in our
 exposure assessments is for pregnant
 women and children an action level
 kicks in at about 0.5 [ppm], based on
 exposure assessment.  We frequently
 have people who oppose this level, and
 I want to raise the problem of an FDA
 legal standard that is an effect of 1,
 and then when the health assessors are
pushed to the wall and asked what
 level is safe for pregnant women and
 children, and we finally come out with
 something that is less than 0.1. Can
you tell us how to explain that to them?

 Dr. Bolger:
     It is a problem of comparing apples
 and oranges.  We continually box
 ourselves in by forcing ourselves to
 answer the question "Is it safe?" Then
 we end up agonizing over the data
because we are trying to describe a level
that is "safe." When we talk about a
 contaminant like methylmercury, and this
 is the case with many contaminants
 where we have a background level of
 exposure in the
 population of con-       ______^^_
 cern, the question we
 should be asking
 ourselves is "What is
 the risk associated
 with a particular	
 exposure?" Attempt-
 ing to define a safe
 level of exposure is not a useful exercise
 on a population or individual basis. Is
 the risk low or high or somewhere in the
 middle? If we do not ask this question,
 either as individuals or as a population of
 consumers, then we cannot make rational
 decisions as to the level of effort that will
 reduce the risk in this most meaningful
 way. In the end, it appears that there is a
 discrepancy between what the FDA has
 done in terms of its action level and what
 the EPA has done in terms of the devel-
 opment of a reference dose. This
 difference is more apparent than  real
 because you are comparing two different
 processes. The action level was devel-
 oped for commercial species and in-
 cluded considerations of not only the
 available hazard information, but other
 relevant information (e.g., background
 environmental levels, analytical capabil-
 ity, etc.). In contrast, fish advisories do
 not include a consideration of the
 consumption of commercial species, but
 rather focus on the consumption of
 recreational species and are designed to
 deal exclusively with sport/subsistence

 Mr.  Hoffmann:
     It is incumbent upon each of the
 state regulators to try to explain, as
 clearly as possible,  the approach that
 the state is using. To do this,  you
 must have  a clear understanding of
 what assumptions go into the FDA
 national "action level."  You must
 recognize that FDA looks at the
 commercial species and the impact
upon commercial fisheries when they
make their judgments.  Some of their
key assumptions might not be  appro-
       box ourselves in by
forcing ourselves to answer
the question *Is it safe?' "

      National Forum on Mercury in Fish
                     priate for a state so a state may
                     choose to deviate from them.  This
                     makes for a longer answer, and it's
                     one that people might not want to
                     hear.  But nevertheless we need to
                     explain that one approach is based on
                     national averages  assuming a mix of
                     different commercial species. For an
                     individual state or an individual water
                     body, there may be factors that are
                     different or unique to that area.
just averages. That was a probabilis-
tic analysis.  Not everyone eats tuna
fish every day. There is a variety, and
the Monte Carlo approach attempts to
model the exposure pattern in the
population which more accurately
reflects what people actually consume,
how often they consume it, and how
the levels vary from day to day.
There is no average consumer. The
numerical average doesn't represent
                      EPA Perspective

                      Dr. John Cicmanec, U.S. EPA

                      Q (Jerry Pollock, California EPA):  Can
                      you estimate when the reference dose will
                      be available?

                      Dr. Cicmanec:
                           Hopefully by the next meeting, 1-2
                      Group Discussion/Question'
                      and-Answer Session

                      Q (Jerry Pollock, California EPA):  Is
                      your evaluation available in printed

                      Dr. Bolger:
                           Yes, there is a manuscript and we
                      recently presented this risk analysis at the
                      international meeting on mercury which
                      took place in Whistler, Canada, this past

                      Q (Jerry Pollock, California EPA): In
                      my experience, it seems that any
                      individual eats only a limited variety of
                      fish.  It's not a good idea to assume that
                      how much fish is sold is an indicator of
                      what people eat. Are there any studies
                      that indicate how many different species
                      offish an individual actually eats,
                      versus using these average numbers?

                      Dr. Bolger:
                           I was just looking at tuna con-
                      sumers, and we were not looking at
Q (Jerry Pollock, California EPA): The
point I'm trying to make is that, when we
look at the consumption of a low-fre-
quency species, there's only a limited
number of people who eat it. But for
those people who eat a lot of monk fish,
it's that number that we need to put in a
Monte Carlo distribution. It's not taking
monk fish and saying 194 million people
eat a few pounds of monk fish, coming up
with a low estimate, and then putting it in
the distribution. It's more like one million
people eat monk fish and that is what we
need to put into a model.

Dr. Stern:
     Your point is well taken, and in
fact the Monte Carlo analysis was
modeling amount of the average mix of
species.  I'm aware of no data that look
at the variability of the mix of species as
well as the variability in the consump-
tion of the overall mix. I would suggest
that a way of getting around that would
be looking at the biological indicators of

Dr. Bolger:
     I agree. That is a real problem for
us. When we look at a species  like
shark, I have no data.  I don't know who
eats it or how often.

Q (Jerry Pollock, California EPA):
There is going to be a consumption
study released from the Santa Monica
Bay Restoration Project that has some
distributions in it. Some of you may be
interested in that. I think the creel
information is useful in that regard.

 Conference Proceedings
 When you look at creel, although it may
 not be a good estimate of how much a
 recreational type person is eating, it will
 give you an idea about how many
 species  offish they eat.  This must be
 worked into the models.

 Dr. Bolger:
     We've talked about the need for
 such studies on a federal level.  There is
 a new fish consumption survey from the
 State of Florida where they're looking at
 all the different species—commercial,
 recreational, and subsistence—for the
 entire state.

 Q (Kim Mortensen, Ohio Department of
 Health): Regarding the table John
 [Cicmanec] showed on how many fish
 can be eaten at safe levels,  can you
 comment on what you think you will be
 coming  out with in your final volume on
 communicating risk and how to get
 advice out to consumers?

 Mr. Hoffmann:
     As John showed, EPA is produc-
 ing a four-part guidance series.  The
 sampling and analysis and consumption
 tables are out already [Volumes 1
 and 2].  Two other documents are under
 way. One is for risk management.  I
 want to  note that the consumption
 recommendations in Volume 2 really do
 not have a risk management component
 built into them, so states  should look
 towards the risk management document
 as well.  It will address issues such as
 appropriate fish consumption  rates.
 States often wrestle with this issue as do
 we at the national level.  The risk
 management document should have a
 comprehensive description  of the
 existing fish consumption surveys.  The
 document will be out in the next month
 or two.  [This has been delayed; it will
 be out in 1995.] The other  aspect is
 how you communicate information that
 is, to a large extent, site-specific. We
 have a risk communication  document
 which is also under way. Dr. Barbara
 Knuth from Cornell is the principal
author of this  document,  and she has
pulled together a lot of examples from
various state agencies. She has taken
general risk communication principles
and applied them specifically to fish
consumption advisories. The document
will include extensive appendices to the
document. They will include mainy
examples drawn directly from various
state agencies. We are sending out the
risk communication document to all 50
states for comment on the final draft.
[The final document will be available in
May 1995,]
               "When you issue a public health
               advisory, there are implications
               beyond that public health advisory."
Q (Jerry
EPA): Rick,
regarding your
comment on     ^———^^———
what EPA
provides and what FDA provides, I think
methylmercury presents a problem for us.
I'm going to have a problem when we issue
advisories if I use the lower RfD or lower
exposures for pregnant women and making
recommendations for fish that Jiave concen-
trations below 0.2 ppm, and not say
anything about commercial fish that have
high levels, like snapper.

Mr. Hoffmann:
     A lot of the discussion on the RfD
choices has focused on what is an appro-
priate reference dose because the refer-
ence dose applies not only to fish con-
sumption advisories but to a whole
variety of other risk assessments. The
issue of the exposure comes later in the

Dr. Bolger:
     This is a constant problem. When
you issue a public health advisory, there
are implications beyond that public health
advisory. Whenever you say something
about methylmercury in  bass, you're
really saying something  about methyl-
mercury in tuna.  I could take a fivefold
reduction in the RfD, which is what we're
looking at, and apply it to the action level.
I'm now down to 0.2, which is the average
for tuna fish. So, what conclusion do you
draw? We're going to take half the tuna
fish off the market? That's where you end

      National Forum on Mercury in Fish
                     up. It's a real problem and we are very
                     aware of it.

                     Q (Greg Cramer, U.S. Food and Drug
                     Administration): I think you 're
                     talking about the very heart of risk
                     management issues here.  What do
                     you do in terms of this information?
                     Waiting for information from
                     Seychelle Islands to come up with an
                     answer that will help us with the fetal
outcome is very important. But if you
take the scenario that it says there are
real low-level effects, what do you do?
Do you tell everyone that we 're going
to ban all seafood because all fish
have mercury?  The dietary changes
as a result of such a decision are
important. Perhaps we need to
provide information on how to  make
informed decisions on how to change
your diet.  These aren't easy issues.

                  National Forum on
                     Mercury in Fish
 A  Review of Fish Consumption
 Robert £. Reinert
 D.B. Wamell School of Forest Resources, University of Georgia, Athens, Georgia

     Transition from fish consumption
     advisories based on U.S. Food and
     Drag Administration (FDA) action
 levels to advisories based on U.S.
 Environmental Protection Agency
 (EPA) risk assessment procedures has
 caused confusion among fishery profes-
 sionals, anglers, and the public.  Why
 do advisories always seem to be issued
 for fish and not for terrestrial animals
 such as squirrels or deer? How good are
 our analytical techniques? What are the
 differences between the older and newer
 advisories? How are these recommen-
 dations established, and how accurately
 do they actually measure the health risk
 associated with eating fish? Anglers
 and the public deserve some basic
 answers to these questions so they can
 better understand this process that can
 have a severe economic and social
 impact on sport fisheries.
Fish—The Perfect
Biological Filter

     If you asked a computer to design
the perfect system for filtering contami-
nants out of water, it probably would
come up with something that looked
like a fish or at least a fish gill. To
enhance the uptake of oxygen from
water, the surface area of a fish's gill is
many times greater than the combined
surface area of the rest of the fish. The
 respiratory tissue of the gill is also
 extremely thin—about 1/10 to 1/64 the
 diameter of a human hair. This ex-
 tremely thin tissue is all that separates
 the water and the contaminants in it
 from a fish's blood.  Virtually all water
 that is pumped across the gill contacts
 this tissue, and most contaminants in
 water rapidly pass from the water across
 the gill membrane into the fish's blood,
 which carries them to various parts of
 the body. Add to this highly efficient
 filter system the fact that fish, like
 terrestrial animals, also accumulate
 contaminants from their food and you
 have an animal that has a high capacity
 for concentrating contaminants from its
     Not only are fish the perfect
 concentrators, but their environment is
 also the ideal collecting place for
 contaminants.  Runoff from land, direct
 input from point sources, and input from
 airborne pollutants add to the contami-
 nant load in an aquatic system. Finally,
 the solvent nature of water tends to keep
 at least some of the contaminant in an
 aquatic system in suspension hi the
 water column, where it is available for
 direct uptake by fish.
Differences Between FDA-
and EPA -Based Fish
Consumption Advisories

    Although FDA action levels and
the EPA risk assessment procedures

      National Forum on Mercury in Fish
                      both use the principles of risk assess-
                      ment and risk management, they are
                      designed to protect different segments
                      of the population. The purpose of FDA
                      action levels established under the
                      authority of the Food, Drug, and Cos-
                      metics Act is to protect the general
                      public from contaminants in fish
                      shipped in interstate commerce
                      (USEPA, 1989). Action levels are
                      developed hi response to national needs
                      and are based on national patterns of
                      consumption that are often different
                      from those of local sport or subsistence
                      anglers (USEPA, 1989). In contrast, the
                      purpose of the EPA risk assessment
                      procedure is to provide the states with a
                      means for informing sport and subsis-
                      tence anglers about the health risks
                      associated with contaminated fish they
                      catch from local waters (USEPA, 1989).
                      These subpopulations of anglers are
                      potentially at greater risk than the
                      general population because they tend to
                      eat larger quantities of fish and because
                      they  often fish the same locations
                           For several reasons, fish consump-
                      tion advisories derived from the newer
                      EPA risk-based-assessment approach
                      generally give a much higher estimate of
                      health risk for a given level of contami-
                      nant  than those based on the FDA
                      tolerance guidelines. The two agencies
                      use different risk assessment methodolo-
                      gies based on different assumptions
                      (USEPA, 1989), and fish consumption
                      rates vary in scope from national (FDA)
                      to local (EPA). Also, FDA action levels
                      are based not only on risk assessment
                      but also on risk management consider-
                      ations such as economic impacts likely
                      to accrue to the commercial fishing
                      industry (USEPA, 1889).  For example,
                      the FDA clearly indicates that its
                      rationale for the current 2 ppm action
                      level for PCBs was a balance between
                      public health protection and the eco-
                      nomics involved in the loss of commer-
                      cial fish to the consumer (USFDA,
                      1984). In contrast, the EPA approach
                      for fish consumption advisories gives
                      full priority to protection of public
                      health.  That some states use different
combinations of the FDA and EPA
procedures to formulate their advisories
further adds to the disparities in con-
sumption advisories among states.
How Low Can We Go?

     During the past 30 years, develop-
ment of more sensitive analytical
instruments and better clean-up tech-
niques for samples have increased the
chemist's ability to detect contaminants
in fish and water about a million-fold.
In the early 1960s, the limit of detection
of many substances was in the parts per
million, which is equivalent to about
2 1/2 ounces of a substance in enough
water to fill a 20,000-gallon railroad
tank car.  Now chemists can detect trace
amounts of most contaminants in the
parts per trillion, which is equivalent to
about 2 1/2 ounces of material hi
enough water to fill one million 20,000-
gallon railroad tank cars.  This many
tank cars would make a train long
enough to stretch from the east coast to
the west more than three times.
     With this increased analytical
ability, chemists now can find trace
amounts of contaminants in most bodies
of water and in most fish. For regula-
tory purposes, many times the question
no longer is whether a particular con-
taminant is in the water or fish, but
rather what effect if any these trace
amounts of contaminants have on the
fish and the animals, including humans,
that eat the fish. Unfortunately, our
ability to detect contaminants in the
envkonment has far surpassed our
ability to assess their effects.
 Risk Assessment Models and
 Calculation of Risk
 Assessment Values

      Because there is a lack of reliable
 human epidemiological cancer data
 involving environmental exposures,
 animal bioassays provide most of the
 information used to predict carcinogenic
 effects on humans. Scientists use

  Conference Proceedings
  mathematical models to extrapolate
  from effects of high doses administered
  to experimental animals to effects of
  low doses on humans corresponding to
  levels found in the environment.  There
  are a number of possible models.
  Depending on the one chosen, the
  estimated increase in cancer incidence
  can differ by several orders of magni-
  tude (Brown, 1982; State of California,
  1985). The model used by EPA is a
  version of the linearized, multistage no-
  threshold model developed by Crump
  (USEPA, 1980). This model leads to
  estimates of cancer risk that are very
  conservative (i.e., it yields the highest
  risk values) (USEPA, 1980, 1989). In
  addition to its conservatism in extrapo-
  lating from high to low doses, the EPA
  model is  also conservative in extrapolat-
  ing from rodents to humans and differs
  from the  FDA in the approach used to
  compensate for the size difference
 between humans and rodents.
      In any dose-response curve there is
 a degree of uncertainty. Thus, scientists
 calculate  confidence limits, based on the
 quantity and extent of the data, that are
 the upper and lower estimates within
 which the estimate of mean risk or "best
 estimate" should fall. EPA reports the
 increased cancer risk as the 95 percent
 upper-bound estimate of the slope factor
 (USEPA,  1980). This procedure
 generally  leads to the highest (most
 conservative) estimate of the risk.  If the
 best estimate or the lower-bound
 estimate were used, the risk value would
 be much lower and could even be zero
 or close to zero.  Thus, the numbers
 reported as an estimate of increased
 cancer risk include margins of safety
 and are conservative estimates of risk to
 human health.
     The  95 percent upper bound is
 expressed mathematically as Ql*, the
 carcinogenic potency factor or slope
 factor (USEPA, 1989). The formula
 P=(X)(Q1*) represents the increased
 lifetime cancer risk (P) caused by
exposure to a daily dose (X) with a
potency factor (Ql *) for 70 years.  The
daily dose is expressed as milligrams of
contaminant per kilogram of human
  body weight per day.  With the daily
  dose, plus the size of each meal, the
  concentration of contaminant in the
  meal, an average size for the human
  body, and a time factor in weeks or
  months, one can calculate the number of
  meals that, can safely be consumed over
  a given time at a given level of in-
  creased cancer risk.
      For contaminants that  do not
  produce cancer but produce other health
  effects such as nerve damage or birth
  defects, the risks are not expressed as a
  probability of occurrence but rather as
  levels of exposure estimated to  be
  without harm. The daily dose for such
  contaminants often is expressed as a
  reference dose (RfD).  Simply put, an
  RfD is a rough estimate of daily expo-
  sure to the human population (including
  sensitive subgroups) that is likely to be
  without appreciable risk of deleterious
  effects during a lifetime divided by an
  uncertainty factor (USEPA,  1993). The
  magnitude of the uncertainty factor is
 dependent on the quality of the toxicity
 data. If there were a substantial amount
 of good data on human exposures, the
 uncertainty factor would be lower than
 if the majority of the data were from
 animal exposures.  The risk manager
 can use the RfD with the same elements
 that were used above (i.e., human body
 weight, time, meal size, and  the con-
 centration of contaminant in the  meal)
 to develop a fish consumption advisory
 for noncarcinogens.
Questions About the Risk
Assessment Process

     Animal bioassays that use high
doses of chemicals are coming under
increasing criticism because many
chemicals that cause cancer at high
doses might not cause cancer at the low
doses more comparable to human
exposure (Cohen and Ellwein, 1990).
Extrapolation from rodents to humans
has also been questioned because of
differences in life span and metabolic
rate, as well as biochemical and pharma-
cokinetic differences (State of Califor-

                                                                    National Forum on Mercury in Fish
                      ma, 1985; Ames et al., 1987). Also, the
                      actual shape of the lower end of the
                      carcinogen dose-response curve is hotly
                      debated.  A noncarcinogen has a thresh-
                      old dose below which there is no
                      observable detrimental effect on the
                      animal. Conversely, a cancer might in
                      theory develop from a single trans-
                      formed cell. Therefore, cancer could
                      develop from a nonthreshold effect
                      initiated by very small doses of a
                      carcinogen reaching the right cell at the
                      right time (State of California, 1985).
                           However, even if there is no
                      threshold, marked alterations in meta-
                      bolic pathways that occur at high doses
                      but not at low environmental doses
                      could result in nonlinearity of the dose-
                      response curve for some animal carcino-
                      gens at low doses (Gehring  and Blau,
                      1977; Hart and Fishbein, 1986). These
                      alterations could result in disproportion-
                      ately high incidences of cancer at high
                      doses. If a carcinogen does have a
                      threshold or if the dose-response curve
                      is not linear at low environmental
                      concentrations, the cancer risk could be
                      much less than that predicted by the
                            About the only assumption on
                      which all factions involved in the risk
                      assessment controversy agree is that
                      decreasing the dose decreases the risk.
                      EPA's present conservative approach
                       assumes that any detectable amount of a
                       carcinogen has the potential for induc-
                       ing cancer (i.e., there is no  threshold).
                       EPA takes this stance because cancer
                       researchers cannot determine with any
                       degree of certainty the minimum levels
                       at which substances cause cancer.
                       Another argument suggested in favor of
                       the conservative approach is that
                       exposure to low concentrations of a
                       variety of substances could have an
                       additive or synergistic effect (State of
                       California, 1985). Viewed in this
                       manner, EPA assumes that at low
                       environmental levels the dose-response
                       curve is linear and, therefore, no level of
                       exposure is free from risk.
                             Another conservative assumption
                       in the EPA risk assessment process is
                       that humans consume contaminated fish
for 70 years at a constant dose (USEPA,
1989).  However, many compounds
listed as animal carcinogens (e.g.,
chlorinated hydrocarbon insecticides
and PCBs) have come into existence
only over the last 30-50 years. Also,
concentrations of many of these con-
taminants in aquatic systems are declin-
ing because of regulatory  actions taken
over the last 25 years. For example,
average PCB levels in coho salmon
(Oncorhynchus kisutch) fillets from
Lake Michigan declined from 1.93 ppm
in 1980 to 0.39 ppm in  1984 (De Vault
et al., 1988). Using the EPA linear
model, this decline leads to about a five-
fold decrease in the estimated cancer
risk. Average DDT levels in Lake
Michigan bloater chubs (Coregonus
hoyi) declined from 9.94 ppm in 1969 to
0.67 ppm in 1986 (Hesselberg et al.,
 1990). This decline would result in
about a 15-fold decrease in the esti-
mated cancer risk.
     Because of the high degree of
uncertainty associated with the risk
 assessment process, there is a tempta-
 tion to delay issuing fish consumption
 advisories until more reliable informa-
 tion is available. Waiting, however, is
 something agencies charged to protect
 human health cannot afford to do.
 Chemicals that cause cancer in experi-
 mental animals and noncarcinogens that
 cause a variety of deleterious effects are
 in the environment and are accumulated
 by fish.  Because of the lack of knowl-
 edge about the low-level effects of these
 chemicals on humans, EPA has adopted
 a very conservative approach to its
 estimates of increased cancer risks and
 other health risks  in the interest of
 public health.  Despite the many short-
 comings of interspecies extrapolation
 models, at present they are the main tool
 for predicting effects of environmental
 and dietary levels of animal carcinogens
 and noncarcinogens on humans.
      Because use of the EPA risk
 assessment process in state fish con-
 sumption advisories is relatively new,
 and because of the many associated
 uncertainties, the process is under
 constant review by EPA and the states.

  Conference Proceedings
  In the future, more states probably will
  use some form of risk assessment
  process in their fish consumption
  advisories. Also, as new techniques for
  predicting cancer risk and other health
  risks such as developmental and repro-
  ductive effects are developed, the states
  will incorporate them into their fish
  consumption advisories. Consequently,
  even where concentrations of contami-
  nants in fish remain the same, health
  risks suggested by the advisories might
 Public Perceptions and Health

      State fish consumption advisories
 can lead the public, and in particular
 anglers, to the perception that fish are
 the only food source that contains
 contaminants. The sensitive instrumen-
 tation now available makes it possible to
 detect trace amounts of contaminants in
 many other foods.  Ames et al. (1987)
 and Schuplein (1990) suggested that
 dietary risks from natural carcinogens
 might be much more important than
 risks from synthetic pesticide residues
 or contaminants in  food. The same risk
 assessment techniques discussed earlier
 can be applied to any food.  Based on
 these calculations, the lifetime cancer
 risk associated with drinking 1 pint of
 milk per day is estimated to be 1 in
 7,143 (Bro et al., 1987).  One contami-
 nant in milk is aflatoxin, produced by a
 mold that grows on corn and peanuts
 that may be used in feed grains.  Simi-
 larly, eating 4 tablespoons of peanut
 butter per day, which also contains trace
 amounts of aflatoxin, results in an
 estimated increased lifetime cancer risk
 of 1 in 1,666 (Bro et al., 1987). Risk
 comparisons included in fish consump-
 tion advisories should include dietary
 risks from other foods,  specifically
 alternative protein sources. These
 comparisons would  be helpful to
 persons who needed to replace sport fish
 in their diet if they followed fish con-
 sumption advisories (Wendt, 1986;
Clark et al., 1987).
       Many anglers also perceive the
  only risk Involved with fishing is the
  health risk from eating contaminated
  fish. Indeed, a risk factor can be
  associated, with everything we do
  including driving to the lake and going
  fishing.  Estimates of such risks are
  derived from actuarial tables. Thus,
  they are a different class of risk than the
  lifetime cancer risks associated with
  eating contaminated fish that are based
  on extrapolations from animal data.
  However, such risks do offer ang;lers a
  way to place the health risks of eating
  contaminated fish in perspective with a
  variety of risks encountered in daily life.
  The lifetime risk of death due to motor
  vehicle accidents is 1 out of every 59
  and deaths due to boating are 1 out of
  every 400 (Clark et al., 1987).  Thus,
  driving to the lake and being out on the
  water also involve risk.
      A simple way anglers can decrease
  contaminant-related health risks associ-
  ated with eating fish is to trim and cook
 the fish properly (Skea et al., 1979;
 Foran et al.., 1989; Gall and Voiland,
  1990). Because many organic contami-
 nants are stored primarily in fish fat,
 removing fatty areas can greatly reduce
 the amounts of these contaminants
 ingested and consequently reduce the
 health risk. Skinning fish removes the
 fatty layer between the skin and the
 flesh. Filleting removes fatty areas
 around the fins.  Other fatty areas  an
 angler can remove are those along the
 top of the backbone, the lateral line, and
 the belly. Baking, broiling or grilling
 fish on a rack drains off fats containing
 organic contaminants.  Puncturing the
 skin also helps fats drain off. Although
 these methods might also result in some
 reduction of heavy metals in fish, the
 reduction will not be as significant as it
 is for organic contaminants  because
 heavy metals are more generally con-
 centrated in muscle tissue.
     In situations where there is an
 advisory on a particular species or size
 class, managers should  make every
effort to let anglers know that other
 species or size classes in that body of
water are safe to eat.  Also, if strict

                                                                  National Forum on Mercury in Fish
                     advisories are being issued on stocked
                     fish, fishery managers might want to
                     reconsider their stocking program.  An
                     alternative might be to stock fish with
                     less of a tendency to accumulate the
                     particular contaminant(s) causing the

                          Several strategies can be used to
                     increase the understanding of and
                     adherence to fish consumption adviso-
                     ries by anglers.  First, the states need
                     to develop a more uniform approach
                     to their formulation of fish consump-
                     tion advisories.  Anglers also need to
                     be made more aware of the assump-
                     tions used in the development of
                     advisories.  For example, the EPA risk
                     assessment procedure assumes a 70-
                     year lifetime consumption of fish.
                     With this information, anglers might
                     choose to adjust their consumption of
                     fish according to their lifetime con-
                     sumption history. The use of a single
                     number as the estimate of health risk
                     (e.g., an increased cancer risk of 1 in
                      100,000)  implies a degree of certainty
                     that, in fact, does not exist
                      (Fessenden-Raden et al., 1987). Risk
                      assessments that contain the full range
                      of risk estimates produced by
                      interspecies extrapolation models (i.e.,
                      upper-bound, best, and lower-bound
                      estimates) would provide risk manag-
                      ers with a more complete view of the
                      risk. However, risk managers must
                      find effective means of communicat-
                      ing this complex array of information
                      to the angler who only wants to know
                      if the fish are safe to eat. Television,
                      radio, newspapers, and magazines are
                      important sources of information for
                      anglers (Cable and Udd, 1990). Risk
                      communicators need to do a better job
                      of using these media to inform anglers
                      about fish consumption advisories.
                           Risk communication problems
                      associated with explaining fish con-
                      sumption advisories involve us in a
                      classic "bad news, good news" situa-
                      tion.  The bad news is that we live in a
world contaminated with chemical
compounds. Aquatic systems are
sinks for these compounds, and fish
have a remarkable capacity to concen-
trate them. Relatively few of the
hundreds of chemicals that have been
identified in aquatic systems are
monitored routinely. Finally, we have
little information about the chronic
effects of many of these compounds
on fish and humans and even less
information about their additive or
synergistic effects.  The good news is
that aquatic systems are remarkably
resilient.  If a contaminant is pre-
vented from entering these systems,
its concentration in water, sediments,
and fish declines. Dramatic declines
in DDT and PCB concentrations in the
Great Lakes over the past 20 years are
good evidence of this (De Vault et al.,
1986, 1988; Hesselburg et al., 1990).
     Further good news about fish
consumption advisories is that they
increase public interest in and concern
for water quality. Proper application
of risk communication can increase
anglers' understanding of fish con-
sumption advisories, keep them
interested in fishing, and help channel
their legitimate concern into actions
that will result in stricter water quality
regulations.  The end result of such
 actions will be improved water qual-
 ity, which will benefit the health of
 the fish and the health of the people
 who eat them.

 Ames, B.N., R. Magan, and L.S. Gold.
      1987. Ranking possible carcino-
      genic hazards. Science 236:271-
 Bro, K.M., W.C. Sonzagni, and M.E.
      Hanson. 1987. Relative risks of
      environmental contaminants in the
      Great Lakes. Environ. Manage.
 Brown, C.C.  1982. High to low-dose
      extrapolation in animals.  In J.V.
      Rodricks and R.G. Tardiff, eds.,
      Assessment and Management of

Conference Proceedings
     Chemical Risks, pp. 57-59. Ameri-
     can Chemical Society, Washing-
     ton, DC.
Cable, T.T., and E. Udd. 1990. Effec-
     tive communication of toxic
     chemical warnings to anglers.  N.
     Am. J. Fish. Manage. 10:382-387.
Clark, M.J., L. Fink, and D. De Vault.
     1987. A new approach for the
     establishment of fish consumption
     advisories. J. Great Lakes Res.
Cohen, S.M., and L.B. Ellwein.  1990.
     Cell proliferation in carcino-
     genesis. Science 249:1007-1011.
De Vault, D.S., M.J. Clark, G. Lahvis,
     and J. Warren. 1988. Contami-
     nants  and trends in fall run coho
     salmon. J. Great Lakes Res.
De Vault, D.S., W.A. Willford, R.J.
     Hesselberg, D.A. Nortrupt, E.G.S.
     Rundberg, A.K. Alwan, and C.
     Bautista.  1986. Contaminant
     trends in lake trout, Salvelinus
     namaycush, from the upper Great
     Lakes. Arch. Environ. Contam.
     Toxicol. 15:349-356.
Fessenden-Raden, J., J.M. Fitchen, and
     J.S. Heath. 1987. Providing risk
     information in communities:
     Factors influencing what is heard
     and what is accepted. Sci. Technol.
     Hum. Val. 12:94-101.
Foran, J.A., M. Cox, and D. Croxton.
      1989. Sport fish consumption
     advisories and projected cancer
     risks in the Great Lakes basin.
     Am. J. Public Health 79:322-325.
Gall, K.L., and M. Voiland. 1990.
     Contaminants in sportfish: Man-
     aging risks.  Cornell Cooperative
     and Sea Grant Extension Fact
     Sheet, Ithaca, NY.
Gehring, P.J., and G.E. Blau.  1977.
     Mechanisms of carcinogenesis:
     Dose response.  J. Environ.
     Pathol. Toxicol. 1:163-179
Hart, R.W., and L. Fishbein. 1986.
      Interspecies extrapolation of drug
      and genetic toxicity data.  In D.B.
      Clayson, D. Krewski, and I.
     Munro, eds.,  Toxicological Risk
     Assessment. Vol. I, Biological and
     Statistical Criteria, pp. 3-35.  CRC
     Press, Inc., Boca Raton, FL.
Hesselberg, R.J., J.P. Hickey, D.A.
     Nortrap, W.A. Willford.  1990.
     Contaminant residues in the
     bloater, Coregonus hoyi, of Lake
     Michigan, 1969-1986. J.  Great
     Lakes Res. 16(1):121-129.
Jacobson, J.L., and S.W. Jacobson.
     1988. New methodologies for
     assessing the effects of prenatal
     toxic exposure on cognitive
     functioning in humans.  In M.S.
     Evans, ed., Toxic Contaminants
     and Ecosystems Health: A Great
     Lakes Focus, John Wiley and
     Sons, Inc., New York, NY.
Schuplein, RJ. 1990. Perspectives on
     toxicological risk—an example:
     food-borne carcinogenic risk. In
     D.B. Clayton, I.C. Munro, P.
     Shubiik, and J.A. Swenberg, eds.,
     Progress in Predictive Toxicology,
     pp. 351-372. Elsevier Science
     Publishers, Amsterdam.
Skea, J.C., H.A. Simonin, EJ. Harris,
     S. Jackling, J.J.  Spagnoli, J,
     Synula, and J.R. Colghoun.  1979.
     Reducing levels of Mirex, Aroclor
     1254, and DDE by trimming and
     cooking Lake Ontario brown trout
     and smallmouth bass. /. Great
     Lakes Res. 5:153-159.
State of California Health and Welfare
     Agency. 1985.  A policy for
     chemical carcinogens:  Guidelines
     for chemical carcinogen risk
     assessment and their scientific
     rationale.  Department of Health
     Services, Berkeley, CA.
USEPA. 1980.  Water quality criteria
     documents. Federal Register
     45(231):79318-79378.  U.S.
     Environmental Protection Agency
     Washington, DC.
	.  1989. Assessing human health
     risks from chemically contami-
     nated fish and shellfish: A guid-
     ance manual. EPA-503/8-89-002.
     U.S. Environmental Protection
     Agency, Office of Marine and
     Estuarine Protection and Office of
     Water Regulation and Standards.,
     Washington, DC.

                                                                   National Forum on Mercury in Fish
                     	.  1993.  ABCs of risk assessment.
                          USEPA Journal 19(1):10-15; 175-
                          N-93-014. U.S. Environmental
                          Protection Agency, Office of
                          Communications, Education, and
                          Public Affairs, Washington , DC.
                     USFDA. 1984. Polychlorinated
                          biphenyls (PCBs) in fish and
                          shellfish; reduction of tolerances;
     final decision. Federal Register
     49(10):21514-21520., U.S. Food
     and Drug Administration Wash-
     ington, DC.
Wendt, M.E.  1986. Low income
     families' consumption of freshwa-
     ter fish caught from New York
     State water. Master's thesis,
     Cornell University, Ithaca, NY.

                 National Forum on
                    Mercury in Fish
 Different People, Different
 Approaches:   Risk Management
 and  Communication  hit Minnesota
 Pamela J. Shubat
 Environmental lexicologist, Minnesota Department of Health, Minneapolis, Minnesota

A       diverse population eats
       Minnesota sport fish. Rates of
       fish consumption range from
 people who eat sport fish only a few
 times each year to people who eat fish
 several times a week during the height
 of a fishing season. Populations differ
 in their susceptibility to fish contami-
 nants. As a result, there is a wide range
 of risk associated with exposure to
 contaminants hi fish. Many different
 approaches in risk management policies
 and risk communication practices are
 required to address this diversity of risk.
     Minnesota has issued fish adviso-
 ries for the past 20 years and began
 collecting data on methylmercury in fish
 in 1969.  Minnesota issued its first
 mercury advisories in a 1977 press
 release when levels that exceeded the
 Food and Drug Administration's regula-
 tory level of 0.5 ug/g were found.
 Today the Minnesota Fish Consumption
 Advisory program issues advisories in a
 booklet and through specialized bro-
 chures and supports these with a variety
 of outreach activities. The "advisory" is
 a booklet listing risk-based advice for
eating fish from 505 lakes and 66 sites
on 38 rivers and contains detailed
advice for specific sites, species of fish,
and sizes of fish. Other materials
targeting specific fish consumers
contain very simple guidelines.  The fish
advisory program is flexible and adapt-
able to the needs of all Minnesotans.
 Advice for Chronic

     The Minnesota advisory is in-
 tended to keep a person's methylmer-
 cury blood level below a threshold
 associated with neurological effects.
 For nonpregnant adults, the protective
 level used in Minnesota is 20 ng/ml
 methylmercury in blood, 10-fold lower
 than the 200-ng/ml threshold associated
 with parestliiesia in 5 percent of the
 population studied in Iraq.  According to
 a pharmacokinetic model described by
 Kershaw (Kershaw et al., 1980) and
 the World Health Organization (WHO,
 1990), this 20-ng/ml blood level corre-
 sponds to a dose of 3 x IQr4 mg/kg/d
 when intake and elimination are at
 equilibrium.  This is the same reference
 dose the Environmental Protection
 Agency has published on the Integrated
 Risk Information System. To form an
 advisory, this daily intake is converted to
 the level of mercury in fish that is safe
 to eat on a weekly or monthly basis.  A
 meal is defined as a 227-gram (0.5-
 pound) meal offish for a 154-pound
 person. A person can safely eat fish
 with 0.16 to 0.65 ug/g methylmercury
 once a week, can safely eat fish with
 0.66 to 2.8 ug/g methylmercury once a
 month, and cannot safely eat fish once a
 month if it has more than 2.8 ug/g
methylmercury (Table 1).
    This advice is communicated
through press releases at the opening of
the fishing season, published in a

                                                                    National Forum on Mercury in Fish
                     Table 1. Meal guidelines for persons eating methylmercury-contaminated fish. One meal is
                     assumed to be 0.5 pound cleaned fish (weight before cooking) per 154 pounds human body
Exposure Duration
(1-year period)
1 to 3 weeks
3 weeks to 3 months
3 months or more
Methylmercury concentration in parts per million (ug/g)
0.16 - 0.65
2 meals/wk
1 meal/wk
1 to 3 weeks unlimited 1 meal/wk
3 weeks to 3 months 2 meals/wk 2 meals/mo
3 months or more 1 meal/wk 1 meal/mo
0.65 - 2.8
1 meal/wk
2 meals/mo
1 meal/mo
1 meal/year
0.5 meal/mo
do not eat
2.81 - 4.5
1 meal
1 meal/mo
eat none
do not eat
do not eat
do not eat
                      booklet, and summarized in the
                      annual fishing regulations guide.  The
                      advisory booklet has meal advice for
                      fish in all of the water bodies that
                      have been tested to date, 505 lakes
                      and 66 sites on 38 rivers. This
                      booklet is  available at state parks,
                      national forests, and natural resources
                      field offices, as well as at health
                      departments and university extension
                      offices throughout the state.  The state
                      is now exploring options for a simple
                      and accurate  advisory for untested
                      waters.  Detailed advice for tested
                      waters (the current advisory booklet)
                      would still be used by anglers who
                      want to eat fish more frequently than
                      the recommendations in the proposed
                      general advisory.
                      Infrequent Fish Consumers

                           Many Minnesotans eat sport fish
                      only a few times a year and can use
                      advice that takes a short duration of
                      exposure into consideration. The
                      pharmacokinetic model allows for
                      calculations of acceptable doses for
                      less-than-chronic exposures. Exposure
                      durations of 3 weeks and 3 months were
                      used to develop fish advisories. Advice
                      is shown in table format and consumers
                      find the advice that matches then-
                      exposure pattern (Table 1). Anglers
                      eating sport fish for a few months of the
                      year are advised that it is safe to double
                      the amounts of fish considered safe for
                      chronic consumption. Anglers  eating
sport fish for a few weeks are advised
that it is safe to eat four-fold higher
amounts of fish considered safe for
chronic consumption.
     One important risk management
concern, so far unresolved in Minnesota,
is how to factor in consumption of
commercial fish. A short-term con-
sumer of sport fish who is eating a can
of tuna each week is chronically ex-
posed to mercury and should probably
be following advice for year-round
     Major communication concerns in
developing complex advice for short-
term consumers include questions of
how useful it is to people and whether it
conveys more certainty than what is
appropriate.  In focus groups and
through written feedback, individuals
who have used the advisories in the past
say that they like more, not less, detail.
Minnesota will continue to evaluate
these concerns.
Advice for Fetal Protection

     Methylmercury is particularly
harmful to the  fetal nervous  system.
In humans, the maternal blood level
associated  with developmental delays
in Iraqi children is  four- to five-fold
lower than levels associated  with
paresthesia in adults. This implies a
woman can protect her fetus by
consuming one-fourth to one-fifth the
amount of methylmercury that is  safe
for other adults.

 Conference Proceedings
      Four categories of advice are
 used in the Minnesota advisory:
 unrestricted, one meal per week, one
 meal per month, and do not eat.  For
 any particular site, species of fish, and
 size of fish, women of child-bearing
 age are  advised to use meal advice
 4.3-fold lower than the advice for
 other adults.  For example, a woman
 is advised to eat one meal a month of
 fish that her male counterpart is
 advised  is safe to eat once a week.
 Fish with less than 0.16 ug/g methyl-
 mercury are safe to eat once a week, fish
 with 0.16 to 0.65 ug/g are safe to eat
 once a month, and fish with more than
 0.66 ug/g mercury should not be eaten
 (Table 1).
     This advice is also offered to
 women who may become pregnant. The
 half-life of methylmercury in the
 bloodstream is approximately 50 days.
 Methylmercury uptake and elimination
 reach steady-state after five to six half-
 lives or about one year.  The period of
 time during pregnancy when the fetus is
 most susceptible to methylmercury
 toxicity is not known. That means a
 woman should follow the fish advisory
 for fetal protection at least one year
 before conception.
     After birth, an infant can continue
 to be exposed to methylmercury through
 nursing.  Small amounts of mercury
 pass into breast milk and form the only
 source of exposure a child has until
 weaned and eating fish.  While it is not
 clear what age is no longer particularly
 sensitive to the developmental effects of
 methylmercury, the nervous system is
 still developing during infancy. Minne-
 sota recommends that nursing mothers
 and children under 6 years of age use
 the more restrictive advice for fetal
     One risk communication issue that
 concerns us is that women ask for
 information about commercially avail-
 able fish. The Food and Drug Adminis-
 tration found canned tuna averages 0.17
 ug/g methylmercury (Yess, 1993). A
 62-kg woman who wants to maintain
her blood mercury level at or below the
recommended 4 to 5  ng/ml should not
 eat more than 7 ounces of canned tuna a
 week.  Shark exceeded 1 ug/g methyl-
 mercury in 60 percent of 33 samples of
 shark tested in Minnesota in 1991.
 Tissue levels ranged from 0.2 to 4.9 ug/g
 and averaged 1.4 ug/g methylmercury.
 The safe fetal protection exposure level
 for fish with  this level of mercury is five
 meals a year if that is the only source of
 mercury during  the year. The National
 Fisheries Institute and the Food and Drug
 Administration (1994) advise women to
 limit meals of shark and swordfish to one
 meal a month. Minnesota customarily
 issues "do not eat" advisories when
 methylmercury-contaminated fish cannot
 safely be eaten at a rate of once a
      A risk communication challenge is
 effective outreach to an audience that
 has not traditionally used fish advisories.
 Standard methods of outreach—keyed to
 fishing openers and fishing regulation
 guides—do not target women who do not
 fish.  The Minnesota Fish Advisory gets
 media attention on the sports page, but
 only recently has been covered in the
 food section of newspapers. Primary
 health care providers have been veiy dif-
 ficult to reach. To meet this challenge, a
 brochure intended for women who might
 become pregnant was developed. It ex-
 plains the health  risks of contaminated
 fish and directs women to the Minnesota
 Fish Consumption Advisory. The bro-
 chure also adlvises pregnant women not
 to eat shark or swordfish and to limit
 meals of canned  tuna to one meal a
 week. This brochure, An Expectant
 Mother's  Guide  to  Eating  Minnesota
 Fish,  will be marketed to health care
 providers through newsletters, through
 health maintenance organizations, and di-
 rectly to clinics.
Highly Exposed Population;;

     It is not necessary to know how
much sport fish a population eats to issue
a fish advisory. However, these data are
useful in understanding the range of
consumption patterns and the impact of
the advice. This year 4,000 Minnesotans

       National Forum on Mercury in Fish
                      are being asked, in a random telephone
                      survey, how often they eat meals of
                      sport fish.  Preliminary data suggest
                      approximately 2 percent of the general
                      population eats sport fish once a week or
                      more. During the height of the 1990
                      fishing season, about 5,000 anglers
                      answered similar questions in surveys
                      conducted at fishing sites around the
                      state (fisheries creel surveys). In these
                      targeted surveys anglers reported eating
                      32 grams fish per day (one 0.5-pound
                      meal per week).  These surveys
                      oversample frequent anglers and might
                      represent a high-end exposure. In
                      surveys returned by 337 anglers who
                      received a 1993 Minnesota Fish Con-
                      sumption Advisory booklet, the average
                      consumption was 17 grams per day and
                      20 percent of those surveyed reported
                      eating fish at least once a week.  Any-
                      one eating fish more than once a week
                      faces a potential risk of overexposure to
                      mercury since most game fish tested in
                      Minnesota have more than 0.16 ug/g
                           Minnesotans with the greatest
                      potential of overexposure to contaminants
                      in fish include people who depend on sport
                      fish for food (subsistence anglers) and
                      people who eat highly contaminatedfish.
                      The fish advisory programcollects
                      populations from(l) otheranglers;
                      (2) fisheries personnelandconservation
                      officers; (3) social workers; (4) city,
                      county, and park officials; and (5) the
                      anglers or populations who identify
                      themselves as at-risk. Based oninforma-
                      tion from these sources, highly exposed
                      Minnesotans who havebeeneasily
                      (primarily Southeast Asian), Native
                      American populations, and an indetermi-
                      nate number of urban poor or homeless
                           Minnesota has a large community
                      of Laotian (including Hmong), Cambo-
                      dian, and Vietnamese immigrants.  Ap-
                      proximately 40,000 immigrants have
                      arrived in Minnesota since 1979, and
                      Minnesota has the second largest com-
                      munity of Hmong in the United States.
                      Southeast Asian anglers in Minnesota
tend to fish in large groups at some of
the most contaminated rivers in Minne-
sota. They are observed taking some of
the most contaminated fish, and they also
take home large quantities of fish. The
fish advisory program has collaborated
with the Minnesota Department of Natu-
ral Resources to conduct a limited survey
of fishing and fish-eating habits of this
population. Additional funding for more
work in this area is needed.
     The risk management strategy for
this population has been to develop a
simplified version of the advisory that
focuses on the metropolitan area and
reduces the advice to two categories:
safe (eat all you want) and not safe (one
meal a month and clean the fish to
remove PCBs). The risk communication
strategy entails a combination of personal
interactions, written materials (including
translations), and visual materials. There
are cultural, economic, and language
barriers to communication that result in
poor access to this community. Due to
cultural practices and poor literacy, it is
difficult to reach this population through
health fairs, the mainstream media, or
mailed flyers.  This audience is reached
through community meetings, demonstra-
tions at English and family education
classes, flyers posted at Asian food
stores, and the Asian community press.
Most recently, a Hmong-language video
on fish contamin' nts was produced by a
Hmong televisic  producer, and it will be
shown on public television and distributed
to community organizations.
     The Ojibwe or Chippewa of
Minnesota have identified themselves as
a potentially at-risk population. In
contrast to the Hmong or other Southeast
Asian communities, this population has a
sophisticated knowledge about environ-
mental health, health care, and health
care resources.
     An exposure study was conducted
by the federal Agency for Toxic Sub-
stances and Disease Registry (ATSDR)
in northern Minnesota at the request of a
tribal government concerned about
overexposure to  mercury. Fish adviso-
ries in the area cautioned anglers to limit
consumption of most game fish to one

  Conference Proceedings
  meal a week. ATSDR conducted an
  exposure assessment (asking about meal
  type, frequency, and size) and measured
  blood and hair mercury levels.  ATSDR
  found that only a few families ate fish
  more than once a week and only one
  individual had an elevated level of
  mercury in blood (over 20 ng/ml).
      This band and others innorthern
 theirownfisheries. Abouthalfofthetribal
 governments inMinnesotadistributefish -
 advisories to their members. Therisk
 managementissues associated with this
 population arecomplex because insome
 cases they arecollectingtheirown con-
 taminant andhealth data. Theriskcommu-
 mcationissuesforthis population are also
 andfishingpractices,suchas access to fish
 andtribalrights to state waters, complicate


     The  Minnesota Fish  Consump-
tion Advisory has evolved to a flexible,
  complex format as the needs of anglers
  have changed over the years.  Risk-
  based advisories for methylmercury
  allow for modifications based on duration
  of exposure and reproductive status.  As
  new at-risk communities are identified,
  the risk communication approach is
  modified to tailor the advisory to their

 FDA Consumer.  1994. Mercury in.
      fish:  Cause for concern? FDA
      Consumer  September 1994:5-8
 Kershaw, T.G., P.H. Dhahir, and T.W
     Clarksora. 1980. The relationship
     between blood levels and dose of
     methylmercury in man. Arch.
     Environ. Health 35:28-36.
WHO. 1990.  Environmental Health
     Criteria 101. Methylmercury.
     World Health Organization,
     Geneva. 144 pp.
Yess,N.J. 1993.  U.S. Food and Drug
     Administration survey of methyl
     mercury in canned tuna. J. AOAC
     Int.  76:36-38.


                   National Forum on
                      Mercury in Fish
  Development  of Risk-Based Fish
  Consumption Guidelines  in Georgia

  Randall O. Manning
  Environmental Protection Division, Georgia Department of Natural Resources, Atlanta, Georgia
        As a result of the growing concern
        regarding toxic contamination of
        aquatic resources and the
 increasing amount of information
 available pertaining to toxicity of
 different chemicals and risk assessment,
 the Georgia Department of Natural
 Resources (DNR) formed a committee
 to develop guidelines for monitoring
 fish tissue contamination and issuing
 fish consumption recommendations.
 Committee members  included
 R. Manning, Georgia Environmental
 Protection Division; C. Coomer, Geor-
 gia Wildlife Resources Division;
 J. Crellin, Agency for Toxic Substances
 and Disease Registry; R. Reinert,
 University of Georgia; J. Stober, U.S.
 Environmental Protection Agency; and
 P. Winger, U.S. Fish and Wildlife
 Service. The guidelines developed by
 the Fish Tissue Advisory Committee
 (FTAC) are for a systematic, ongoing
 monitoring plan for rivers and lakes.
 The monitoring strategy consists of two
 tiers of studies.
Primary and Secondary Studies

     The objective of the primary study
is to identify waterbodies where chemi-
cal contaminants are present in fish in
concentrations that might represent a
health threat to anglers while providing
sufficient data to issue specific con-
  sumption recommendations for at least
  two target species. Target species
  recommended for the primary study are
  one bottom-feeding species (catfish) and
  one predator species (largemouth bass).
      A list of recommended target
  contaminants and detection limits,
  including 13 metals and 30 organic
  pesticides/PCBs, was developed.
  Dioxins and dibenzofurans were not
  included on the list of target contami-
 nants. Currently, dioxins/dibenzofurans
 are monitored in fish tissue (whole fish
 and fillets) in the vicinity of five
 bleached kraft pulp mills in Georgia.
 The studies are conducted yearly by a
 consulting firm following a study
 protocol that was approved by DNR.
     For the primary study, three sites
 should be chosen to provide adequate
 coverage of most lakes. More than three
 sites might be needed in larger lakes to
 define the geographic extent of contami-
 nation adequately. Site selection in
 rivers depends on the river reach to be
 covered by consumption guidelines.
 Sampling should be conducted on a
 yearly basis  in late summer through fall.
     Compositing edible fillets from
 individuals prior to analysis provides a
 means of collecting information  on
 average contaminant concentrations
from a large number of fish with a
limited number of analyses. The vari-
ability among contaminant concentra-
tions in individual fish is lost by

                                                                    National Forum on Mercury in Fish
                      compositing. However, an accurate
                      estimate of individual variation is not
                      necessary to meet the objective of the
                      primary study. Therefore, composite
                      samples were recommended to reduce
                      the cost of analysis for the primary
                      study. An edible fillet is defined as the
                      fillet portion of the fish including the
                      bellyflap. For scaled fish, fillets should
                      be scaled but left with the skin on. For
                      fish without scales, the skin should be
                      removed from the fillet. Composites
                      should  contain tissue from five indi-
                      vidual fish for a target species. Tissue
                      from different species of fish should
                      never be mixed to produce  a composite.
                            Fish collected should  be of a size
                      that is representative of what fishermen
                      are likely to catch in the area. Ideally,
                      the smallest fish in a composite should
                      be at least 75 percent of the size of the
                      largest fish. Composites should be
                       prepared with five fish of a similar
                       length  representative of three size
                       classes (i.e., <12 in, 12-16  in, and >16
                       in). This will allow for the development
                       of consumption guidelines based on size
                       classes offish. Three replicate compos-
                       ites for a size class are needed to issue
                       consumption recommendations.
                            The objective of the secondary
                       study is to provide information regard-
                       ing additional fish species  or to further
                       define geographic extent of contamina-
                       tion for water bodies where the primary
                       study resulted in restrictions on fish
                       consumption. Target species for the
                       secondary study should be chosen based
                       on site-specific information related to
                       fish populations and fishing preferences
                       of the local anglers.
                        Data Analysis and Fish
                        Consumption Advisories

                             In the past, DNR has based fish
                        consumption advisories on FDA action
                        levels or tolerances that have been set
                        for mercury, approximately 12 pesti-
                        cides or related degradation products,
                        and PCBs. In recent years, interest in
                        the use of risk-based approaches has
                        increased. With these methods, one can
calculate a quantitative value for risk
from consumption of fish containing
carcinogens. It should be emphasized
that risk calculations are only estimates;
the actual risk cannot be determined.
     Currently, probability is not used
to express the potential for noncancer
toxicity. Instead, the potential for
noncancer toxic effects is evaluated by
comparing an exposure level for a
specified time period with a reference
dose or RfD (i.e., a level of exposure
below which it is unlikely that people
will experience any adverse health
effect). If this ratio, referred to as a
hazard quotient, exceeds unity, there
might be concern for potential
noncancer effects.
      Dourson and Clark (1990) pro-
posed a method to improve the credibil-
ity of fish consumption advisories and
make them more useful for the average
 fish consumer. The proposed model
 accounts for the amount of fish con-
 sumed (one of the most difficult param-
 eters to determine) by making fish
 consumption the dependent variable and
 recommends that, where consumption
 should be limited, advisory information
 be provided as number of fish meals
 allowed per month, week, or day.
       The steps required for evaluation
 of data with the Dourson and Clark
 (1990) model begin with the calculation
 of fish intake from the appropriate RfDs
 for noncancer toxicity or potency factors
 for cancer. The second step is to esti-
 mate the amount of fish consumed per
 meal. Dourson and Clark (1990) sug-
 gested that a difference of approxi-
 mately twofold (0.25 to 0.5 Ib) exists in
 the size of individual fish meals. This
  range of meal size and the frequency of
  fish meals eaten over a given period
  follow a logarithmic scale.  That is, the
  consumption of 3 to 10 grams  of fish
  per day is in the range of eating one
  0.25- to 0.5-lb fish meal per month; the
  consumption of 10 to 30 g/day is in the
  range of eating one 0.25- to 0.5-lb meal
  per week; the consumption of 30 to 100
  g/day is in the range of eating three
  0.25- to 0.5-lb meals per week; and the
  consumption of 100 to 300 g/day is in

    Conference Proceedings
    the range of eating one 0.25- to 0.5-lb
    meal per day. The fish consumption
    advisory proposed by Dourson and
    Clark (1990) is developed from a direct
    comparison of calculated fish intake
    values to the estimated amount offish
    consumed per meal and meal fre-
    quency. However, in the interest of
    simplicity, FTAC recommended
   reducing the number of recommenda-
   tions from six to four by categorizing
   consumption greater than 30 g/day (3
   meals/week and 1 meal/day) as nonre-
       The use of this model allows the
   release of a gradient of recommenda-
   tions ranging from unlimited consump-
   tion to complete restriction with
   intermediate recommendations based
   on fish meals per week or month.
   Another advantage of the method is
   that it enables one to conduct risk
   assessments for mixtures (i.e., assess-
  ments when more than one chemical is
  present in fish tissue) for either car-
  cinogens or toxics  with similar organ
      Management decisions must be
  made concerning appropriate inputs for
  the basic model parameters. For
  analyses of carcinogens, an appropriate
  nsk level, a standard body weight, and
  an exposure duration must be chosen.
  For analyses of noncancer toxicity,
  only body weight and exposure dura-
  tion must be chosen. FTAC recom-
  mended that in the model a risk level
  of lO"4 be used for analysis of carcino-
 gens, 30 years as the exposure dura-
 tion, and 70 kg as the adult body
 weight in evaluations for both carcino-
 gens and toxics.
 Special Considerations
 Related to MethySmercury

     Methylmercury presents a unique
 problem when evaluated as a toxic in
 the model described herein. The RfD
 for chronic toxicity is 3 X 1Q-4 mg/kg-
 day. Because of concerns of develop-
mental toxicity, U.S. EPA's Office of
Water has recommended the use of a
   provisional RfD of 6 X 10-5 mg/kg-day
   for women of reproductive age and
        In the interest of simplicity and
   minimizing confusion when converting
   to a new approach, FTAC recom-
   mended that only one set of consump-
   tion guidelines, for adult chronic
   exposure, be produced. However, to
   ensure that women of reproductive age
   and children are adequately protected,
   they should, be encouraged to limit
   consumption to a greater extent than
   recommended in the guidelines. For
   example, women of reproductive age
   and children should limit consumption
   as follows:
    If the guidelines
    no restriction
    1 meal/week
    1 meal/month
    do not eat
   Limit consumption
   1 meal/week
   1 meal/month
   do not eat
   do not eat
      To evaluate the degree of "protec-
 tiveness" achieved with this strategy
 compared to that using U.S. EPA's
 provisional and chronic RfDs for
 methylmercury, comparative values are
 provided in Table 1.

     DNR used a communications
 consultant (Ringo Research Associates,
 Atlanta, Georgia) to assist in acquiring'
 public input for the proposed model
 and developing a communication
 strategy. In the fall of 1993, six meet-

Table 1. Ranges of allowable tissue concentrations for mercury
and categories of meal advice                       ««ry
                         Fish Intake and Meal Advice

Hg,T (chronic RfD)
Hg,T(G A advice)
   >30g      30-llg
No restriction  Imeal/wk
            10-3g      <3g
           1 meal/mo  Donoteat

                                             National Forum on Mercury in Fish
ings were held around the state to
provide the public an opportunity to
learn about the proposed method and
provide input. Several different types
of "stakeholders or customers" were
identified and invited to each meeting.
These included environmental activists,
lake association representatives,
owners of lakeside businesses (bait
shops, marinas), fishing guides, and
local sportfishermen. Meeting size was
limited to approximately 15 people so
that an informal discussion group
 format could be used. A brief overview
 of the proposed method (15 minutes),
 prepared by the consultant for the
 general public, was given and then the
 floor was opened for discussion. Total
 meeting time was limited to 2 hours. A
 seventh meeting was held for Georgia
 Power Company and the Corps of
 Engineers, two major stakeholders
 managing reservoirs in Georgia. The
 format was similar with the exception
 that more people attended (-30), a
 more technical presentation was
 presented, and time for discussion was
  not limited.
       The consultant facilitated the
  discussions to ensure coverage of
  several topics including first impression,
  positive or negative; need for new
  method, reasons for change; suggestions
  for communication/education; media
  exaggeration; the trust issue; putting risk
  or hazard in perspective; and special
  communication needs.
       Responses during the meetings
   were generally favorable regarding the
   need for a more informative, easily
   understandable system of conveying
   consumption information, and the
   format proposed. Some participants
   had difficulty in understanding the
   change in philosophy from the current
   systems in which  only "do not eat"
   information is issued, to the proposed
    systems in which  different types of
    information will be issued, allowing
    the individual more latitude in deter-
    mining how to restrict fish consump-
    tion. However, as participants' ques-
    tions were answered and discussed
    openly, most people became comfort-
able with the concept by the end of the
meeting. Much of the discussion
focused on how to educate people to
understand the proposed system and
how to ensure that the information gets
to everyone.

 General Recommendations for
 Communication Strategy
     1. Continue to involve stakeholders
      in the process as the method is
      refined and unproved.
     2. Educate and use field personnel
       (rangers, fisheries biologists, and
       others) as front-line communica-
       tors. They deal directly with the
       public and their credibility is
       often better than that of regula-
       tors from DNR. The importance
       of one-on-one communication
       and communication to small
        groups (fishing clubs, local
        organizations, etc.) via field
        personnel was mentioned fre-
      3. Identify key local "communica-
        tors" in lake areas. Educate them
        and use them to convey informa-
        tion.  Examples of these people
        include individuals who have
        considerable influence on opin-
        ions  of fishermen, such as fishing
        guides or marina and boat ramp
      4. Different types of information
        will  be needed for different
        customers.  Identify those needs
        and  target information accord-
        ingly-                ,   ,
      5. Keep information simple, clear,
         and easy-to-understand. Be
         prepared to repeat a consistent,
         simple message over and over.
      6. Put risk (or hazard) hi perspective
         for people.

    Specific Recommendations for
       1. Place articles, preferably written
         by  outdoorsmen, in sporting and
          outdoor magazines to describe/
          discuss new method in first year.

Conference Proceedings
    2. Produce a booklet with a brief
      discussion of the process DNR
      uses to monitor and assess
      contamination, how DNR's
      recommendations are developed,
      what contaminants are found in
      fish, and what the health risks
      (and benefits) from consuming
      fish are, followed by tables of all
      the recommendations for differ-
      ent water bodies.
    3. The booklet should be updated
      yearly and available where
      fishing licenses are purchased, at
      marinas and bait shops, and from
      all DNR offices.
    4. Produce color-coded tables
      (signs) for posting at boat ramps.
    5. Produce a short video and/or
      slide set describing the program
      that can be used by field person-
      nel when speaking to groups.
Current  Status

     Sampiles of fish were collected
from 27 lakes and approximately 20
river reaches in 1991,1992, and 1993.
Collection sites have been designated
for the fall of 1994. Development of
educational materials and refinement of
a communication strategy are currently
under way.  The system described herein
has not been officially approved by
DNR, but plans are continuing for an
implementation date of spring 1995.

Dourson, M.E., and M.J. Clark. 1990.
     Fish consumption advisories:
     Toward a unified, scientifically
     credible approach. Reg. Toxicol.
     Pharmacol. 12:161-178.


                     National Forum on
                        Mercury in Fish
   Managing and  Communicating
   Mercury Risks  in Arkansas
   Kent Thornton
   Arkansas Mercury Task Force Coordinator, FTN Associates, Little Rock, Arkansas'
     It is axiomatic that communication is
     critical in all phases of risk assess-
     ment and risk management. Yet, risk
  communication is typically the last
  activity considered as part of either risk
  assessment or management. We found
  that establishing lines of communication
  early in the process was critical in
  addressing the mercury problem in
      In the summer of 1992, Louisiana
  issued a fish consumption advisory
  because of mercury contamination
  found in fish taken from the Ouachita
  River just below the Arkansas-Louisiana
  border.  Historically, mercury concen-
  trations were negligible in fish collected
  in the Ouachita River in Arkansas, so
  the fish consumption advisory was a
 surprise. We had previously collected
 fish from the lower portion of the
 Ouachita River, but had frozen the
 samples because funds were not avail-
 able for a complete contaminate scan.
 These fish samples were analyzed and
 found to contain mercury concentrations
 that were near or exceeded the FDA 1
 mg/kg action level for tissue. Subse-
 quent sampling offish tissue from the
 Ouachita River indicated predator fish
 exceeded the FDA action level, and a
 fish consumption advisory was issued
'Contributing authors, by agency, include P. Burge
S. Evans and T. McChesney, Arkansas Department of
Health; J. Giese and A. Price, Department of Pollution
Control and Ecology; Mike Armstrong and Don
Turman, Game and Fish Commission, and J. Nix, Ross
Foundation and Chair, Arkansas Mercury Task Force
  for the lower Ouachita River in Arkan-
  sas (Figure I). Based on these findings,
  we initiated a planned, systematic
  approach for addressing the problem that
     1. Developing a strategic approach
        to address risks from mercuiy
     2. Boundingthescopeoftheproblem.
     3. Managing and communicating
        risks for fish mercury contamina-
  Identifying the Strategy

      The first activity was to address
  initial public concerns about the health
  risks from eating mercury contaminated
  fish. A communication approach was
  developed that included:
     1. Public meetings.
     2. Free blood screening for anyone
       in the affected areas.
     3. Fish consumption advisory
    4. Information dissemination at
       county fairs, bass clubs, church
       groups, Rotary and Kiwanis
      clubs, and other civic organiza-
     The Governor established a
Mercury Work Group that included
public and special interest group mem-
bers and was chaired by a well-known
scientist who was respected and trusted
throughout the state. This Work Group
kept the Governor, Legislature, press,

                                                                National Forum on Mercury In Fish
                  and public informed on all aspects of the
                  mercury problem. The Work Group's
                  strategy was guided by a set of clearly
                  defined questions:
                      1. What is the extent and magnitude
                        of the problem?
                      2. What are the risks to human
                      3. Why do we have the problem and
                        what are the sources of the
                      4. What can we do to manage or
                         solve the problem?
                       5. Have we always had this problem
                         or did it develop recently?
                        An objective, scientific approach
                   was developed to answer these ques-
                   tions. The approach was designed to
                   provide incremental information on
                   these questions. The approach also was
                   prioritized to:
                       1. Continue to communicate infor-
                         mation and results to the public
                          on the mercury problem through
Figure 1. Shaded area of Ouachita River in eight southern Arkansas counties was
initial area for fish consumption advisories.
     a Mercury Task Force and a
     Mercury Advisory Committee.
   2. Assess the magnitude and extent
     of the problem and the potential
     risk to public health.
   3. Formulate initial management
     actions to ameliorate the problem.
   4. Identify possible sources and
     causes of the problem.
   5. Evaluate historical trends.
     This strategic plan was submitted
to the Governor and subsequently
funded by the Arkansas Legislature.
The next step was to bound the scope of
the problem and establish a baseline for
future comparison.
Bounding the Scope of the

     A systematic sampling approach
was used to implement the strategic
plan. This included sampling point
               sources discharging
               directly into the
               Ouachita River or its
               tributaries, sampling
               from the border up-
               stream to determine the
               extent of the problem,
               and sampling areas
               where mercury contami-
               nation might be ex-
               pected based on stream
               characteristics as well as
               where it was not ex-
                     A two-phased
                approach was followed,
                with screening sam-
                pling conducted as part
                of Phase I (Figure 2)
                and more intensive
                Phase n sampling
                conducted where
                confirmation of screen-
                ing results  and/or
                greater geographic
                definition of the prob-
                lem was needed. The .
                largemouth bass was
                 used as the indictor
                 species for screening

C....:,;c.ice Proceeciings
    because it is a popular sport fish in
    Arkansas, is at the top of the aquatic
    food chain, and biomagnifies mercury
    (Figure 3), with concentrations exceed-
    ing FDA action levels in larger fish.
    Fish composites were taken and grouped
    by length class.
         When fish mercury concentrations
    exceeded or were near the FDA action
    level  of 1 ppm (mg/kg), confirmation
    sampling was immediately conducted.
   If the confirmation samples also ex-
   ceeded the action level, a fish consump-
   tion advisory for that body of water was
   issued. Phase H sampling also included
   developing fish length-mercury relation-
   ships for selected species of popular
   sport fish such as the white crappie and
   sunfish (Figures 4  and 5). These fish
   length-mercury relationships were
   critical in reducing some of the fish
   consumption advisories to include only
   specific species such as the largemouth
   bass greater than 16 inches in length
  rather than all predator fish. This
  reduction had important
  economic consequences
  for southern Arkansas,
  particularly for fishing
  license sales, bait shops,
  fishing stores, and
  associated  businesses.
  Without these relation-
  ships, the fish consump-
  tion advisories would
  have been retained for
  all predator fish, regard-
 less of species or length
      Good geographic
 coverage of the Phase n
 sites was ensured by
 overlaying a random,
 systematic sampling grid
 on Arkansas and com-
 paring the sites that had
 been sampled in Phase I
 with the  randomly
 selected  sites. This
 enhanced sampling grid
 was provided by the
EPA Environmental
Monitoring and Assess-
                                        and indicated there were geographic
                                        areas that did not have adequate cover-
                                        age.  Additional fish samples were
                                        subsequently collected in those areas.
                                             In addition to the fish samples,
                                        sediment and water samples also were
                                        collected throughout the Ouachita River
                                        basin and analyzed for total mercury. In
                                        general, the concentrations of total
                                        mercury in the water and sediment
                                        samples were relatively uniform
                                        throughout the Ouachita River basin,
                                        being within a factor of 2 for all
                                        samples. The average total mercury
                                       concentration in sediments throughout
                                       the Ouachita River basin was 0 11 mg/g
                                       or ppm (sd = ± 0.21, n=l 11). In addi-
                                       tion to sediment sampling, geologic
                                       samples of rocks were collected
                                       throughout the Ouachita Mountains.
                                       These rocks were ground and analyzed
                                       for total  mercury. The average total
                                       mercury concentration in 724 rock
                                       samples from the Ouachita Mountains
                                       was 0.17 ug/g (sd = ± 0.24).  The

                          o      350      400     450      500      5SO
                                 Length (mm)
 Figure 3. Increased mercury concentration in largemouth bass as a function ot
 length (age) in Felsenthal National Wildlife Refuge.
       'lOO     150      200      250      300      350
                                  Length (mm)

   Figure 4. Length-mcrcury relationship in white crappie in Felsenthal National
   Wildlife Refuge.
                                                                   National Forum on Mercury in Fish
frequency distributions of
total mercury in sediments
and rocks were remark-
ably similar (Figure 6).
While this does not
confirm geologic origin as
the source of the mercury,
it does indicate there
might be other sources in
addition to atmospheric
deposition. These studies
are being continued to
determine whether
 geologic sources can be
 readily methylated.
      The information
 collected as part of the
 sampling effort was
 communicated to the
 public and used to initiate
 management actions.

  Managing and
  Risks from Fish

       The strategic plan
  proposed that two groups
  be established to manage
  and communicate the risks
  from fish mercury con-
  tamination. These two
  groups are the Arkansas
  Mercury Task Force and
  the Arkansas Mercury
  Advisory Committee.
       The Arkansas
  Mercury Task Force is the
  coordinating group for
  mercury studies in Arkan-
   sas. The Task Force
   consists of an independent
   Chair and Coordinator, the
   Directors of the respon-
   sible state agencies—
   Arkansas Department of
   Health, Department of
   Pollution Control and
   Ecology, and Game and
   Fish Commission—and
    the Director of the Univer-

    Conference Proceedings

    sity of Arkansas Water
    Resources Research Center.
        The Arkansas Mercury
    Advisory Committee is one
    of the principal vehicles for
   communicating information
   to the public. This commit-
   tee is chaired by a knowl-
   edgeable, respected layper-
   son from southern Arkansas,
   and has membership from
   federal, state, and local
   agencies such as the USDA
   Extension Service, FDA, and
   Arkansas Science and
   Technology Authority;
   private sector and civic
   organizations such as electric
   utilities; special interest
   groups such as the Arkansas
   Wildlife Federation; and the
  press, including the Arkansas
  Educational Television
  Network.  Each of these
  members serves as a liaison
  to communicate information
  to their respective agencies/
  organizations and their communities.
      During the early stages of identify-
  ing the mercury problem, it was obvious
  that, while public meetings were very
  important for conveying information,
  these meetings were too time-consum-
  ing and provided information to only a
  small segment of the community. A
  video, Mercury in Fish: A Problem We
  Can Live With, was developed by the
 Task Force for distribution throughout
 the state. The Mercury Advisory Com-
 mittee was one of the primary outlets
 for distribution, but the video also was
 provided to all county and regional pub-
 lic health units, conservation offices,
 wildlife refuges, state parks, schools,
 and similar organizations. In addition
 to being the medium watched by the
 high-risk groups (young children, preg-
 nant women, and women who might
 become pregnant), it can be shown to
 almost any audience. The county health
 units, for example, put the video on
 continuous loop in their waiting rooms,
particularly for the WIC and Prenatal
Health Care programs.
                         in Wuegillcrappie in Felsenthal National
      Fish consumption advisory
 brochures are prepared on at least a
 quarterly basis and distributed through
 all bait shops, sporting good stores, and
 marinas.  In 1995, the brochures also will
 be distributed with both fishing and
 hunting licenses.  Special articles have
 been prepared for outdoor magazines,,
 newspapers, medical journals read by
 Arkansas physicians, and newsletters of
 special interest: groups and civic
 organizations. Using multiple media is
 critical because the high-risk groups
 can be difficult to reach with informa-
 tion on the risks from mercury contami-
Lessons Learned

     The following lessons were
learned during the past 2 years of
experience in Arkansas:
    1. Communication is the issue. It is
      critical that a broad group of
      communicators be trained and
      used in communicating informa-

                                        National Forum on Mercury in Fish
    tion on the risks of consuming
    fish contaminated with mercury.
    These communicators include the
     • Health officials.
     • Fisheries and wildlife conser-
       vation officers.
     • Extension service personnel.
Community laypeople.
Public officials and other
individuals who have contact
with the public, in particular,
contact with the high-risk
consumer groups.

                      0.4        0.8       1.2       1.6    2.0
                          Mercury (ug/g)
Figure 6. Joint distribution of sediment mercury concentrations in the Ouachita River
and rock mercury concentrations in the Ouachita Mountains.

Conference Proceedings
   2. Keep the message the same and
      keep it simple. Individuals need
      to hear the same message 4-6
      times before they fully under-
      stand what is being said. Con-
      tinually changing the message
      confuses communication.
   3. Use multiple media because the
      high-risk group is hard to reach.
      This should include:
      • Videos
      • County health unit handouts.
      • School programs and
        children's messages.
      • Radio public service an-
      • Television news reports and
        public service announce-
      • Educational television.
      • County/state fairs.
      • Bass tournament brochures.
      • Newspapers and newsletters,
  4. Develop an organized approach
     to distributing information.  Out-
     reach committees are critical at
     the local, state, and national levels.
 5. Develop an approach to manag-
   ing and communicating informa-
   tion on the risks from mercury
   contamination that is founded on
   scientifically sound, strategic
   approaches that have a clear set
   of questions to be answered; that
   are conducted through coordi-
   nated, cooperative efforts of all
   responsible agencies; and that
   use a systematic sampling
6. Keep an open-minded perspective
   on mercury sources and manage-
   ment options and alternatives. It
   is unlikely that there is a single
   source or a single solution.
  Focus on incremental increases in
7. Identify interested, informed
  people to participate. Do not
  settle for the individual who
  currently is not busy. We made
  progress because we had indi-
  viduals who were concerned
  about the problem, aggressively
  attacked it, and were not con-
  cerned about agency affiliations.


                 National Forum on
  Day Two: September 28t199^\
                   Mercury in Fish
 Questions and Discussion:
 Session Two
       After each speaker's presentation,
       an opportunity for questions and
       answers was provided.  Time
 was also allotted for a group discussion/
 question-and-answer session.
 A Review of Fish Consumption

 Dr. Robert Reinert, University of

 Q (Arnold Kuzmack, U.S. EPA,
 Headquarters): Regarding your
 experience of success communicating
 with people by  comparing [one type of
 risk] to other risks, our experience
 trying to do that is generally very-
 negative. People are not reacting so
 much to the quantitative information
 as to the anger that somebody has
 done this to them. This kind of com-
parison makes them more angry
 because they perceive that you're
 trying to minimize what they're
 concerned about.

Dr. Reinert:
    The worst way to do this is to have
 an article pop up in the paper. You have
to go about it gradually, before these
things are released. Build a base.  It
doesn't come easy. We're going to get
hit and we're going to get hurt. If you
work at it and build a base, you can
 slowly educate the public. Look at
 cigarette smoking as an example. We
 can [talk about fish consumption risks]
 without terrorizing people and having
 them quit the sport.

 Q (Kim Mortensen,  Ohio Department of
 Health): I disagree with you on parts of
 your approach. I think you 've underes-
 timated the rage factor. We  must
 understand how much rage people have
 about imposed risk. There is a problem
 of trivializing risk. When I go out to the
 public and tell them I'm concerned
 about a risk from PCBs or cancer,  I go
 out as an expert. They look to me for
 advice. And if you go out there and
 trivialize the risk, your message has
 been severely undercut. From my
 experience, you are putting across a
 mixed message.

 Dr. Reinert:
     I'd never go out there and trivialize
 what work has been done. I tell them
 this is the best we're doing with what
 we've got and that it is a problem. But,
 pay attention to where the advisories are.
 You always get two extreme groups with
 a lot of power.  One group will disregard
 all the advisories, and the other group
 will be terrified of them and quit. I think
 we tend to underestimate the audience.
Be honest with the audience; get the in-
formation to them. I don't think we
should downplay, but I think you have to
bring them into some perspective. There

                                                                 National Forum on Mercury in Fish
*Our ability to detect things
has certainly surpassed our
ability to say anything about
the effects.9*
 are many risks involved in things, other
 than fish, that have contaminants in them.
 Tell them that.

 Q (Rob Reash, American Electric
 Power):  I thought your comment about
 detection limits surpassing the ability to
 elucidate effects in the real world was
 very interesting. At this point we 're in
 an era where that is not a theoretical
                    position, but is a
                    real one that's
                    happening.  I'd
                    like to bring up an
                    example of
                    detection limits
__________    going down using
                    fish consumption
 advisories to take water quality stan-
 dards further down. I'm not talking
 about subpopulations that are at risk.
 My point is when agencies adopt these
 very, very low water quality standards.
 Take, for example,  in the Great Lakes
 where EPA has proposed 0.18 nano-
 gram per liter wildlife criteria for
 mercury. Now all of a sudden all these
 health effect studies are going to be
 done, which won't be completed for 3 to
 4 years. Now all the agencies want to
 study mercury levels in fish and see
 where we've been. It seems that things
 are a little backwards.

 Dr. Reinert:
      A lot of these advisories have led
 people to think  that water quality now
 is getting worse and worse. I think
 that for many things it's not.  It's
 getting better than it was. If you look
 at fish populations, birds of prey
 populations, they're coming back.
 Now we're at a stage where it's not so
 much from a point source, but from
 airborne pollutants, and production
 levels seem to be leveling off. Now
 these animals that are reproducing, are
 reproducing, but we're seeing some
 effects. So we've gotten over one
 layer, but we've gotten to the next
 layer, which is  developmental effects.
 It's a touchy issue.  Our ability to
 detect things has certainly surpassed
                                                           our ability to say anything about the
                                                           effects.  Anybody who talks about
                                                           zero guidelines or zero tolerances is
                                                           kidding  themselves.
Different People, Different
Approaches:  Risk Manage-
ment and Communication in

Dr. Pant Shubat, Minnesota Depart-
ment of Public Health

Q:  What level of contamination are
you using to decide what is safe and
unsafe for the Hmong?

Dr. Shubat:
     It's focused more on PCBs
because PCBs drive the urban area
advisories. We did bend the rules a
little, and we found out from people
who work with them regularly that it
is best to present things in a positive
way. For example, the brochure says
which fish are safe to eat, not what
fish not to eat. The fish that are the
most contaminated with PCBs we say
to eat once a month, whereas with
other anglers we say do not eat. We
also have detailed instructions on how
to clean and cook the fish to reduce
the PCB levels.

Q (Jerry Pollock, California EPA):
Did you quantify the level offish
consumed by the Hmong population?

Dr. Shubat:
     Yes, as a prerequisite to the Hmong
video we did some interviews. We
interviewed 30 individuals and they don't
have that high a consumption. It looks
like they're doing a lot of fishing because
they are very visible, but they distribute
fish among themselves. They do eat
more than the average angler. We have
to do more work. What criteria did you
use for saying "Eat them, don't eat
those"? We said, "Eat all the pan fish you
want." For predatory fish, we said, "Eat
one meal a month if you clean the fish."

 Conference Proceedings
 Q (Lee Weddig, National Fisheries
 Institute): I think there is a great
 distinction between saying "you can eat
 six meals a year" and a "don't eat"
 advice.  The consumption data would
 show that the typical number of meals
 consumed for a various species is 5 or 6
 times per year.  You are cutting out
 normal consumption.

 Dr. Shubat:
     People who are getting the
 message about the tuna and shark
 advisory are people who are pregnant
 or are planning to be pregnant.  Six
 meals a year during pregnancy is a
 more concentrated exposure.  We
 don't know if it's safe. It's probably
 more than 1.5 ppm.

 Luanne Williams, North Carolina
 Department of Environmental Health
 and Natural Resources: North Carolina
just completed a random sampling of
 shark tissue from processing plants.  We
 collected 32 samples and the average
 mercury level was greater than 1, which
 has prompted additional concern for
 other top predator marine species. I'm
 interested in obtaining tissue sampling
 results from the other top predator
 marine species. This is a plea for
 information. I'm also interested in
 obtaining some information on adviso-
 ries that have been issued from other
 states on marine species where elevated
 mercury levels have been detected.

 Q (Gale Carlson, Missouri Department of
 Health): Have you done any studies to
 determine if people read and how well
 they understand the advisories?

 Dr. Shubat:
     We have, and we've found that
 50 percent randomly surveyed have
 heard of the advisories.  We asked
 them in three different ways if they've
 followed the advisories, and at least
 half of those who answered do follow
 them. However, there are many
 people who answered "no" because
 they know the advisory does not apply
 to them or they are already fishing in
 the right areas. Our brochures are on
 different reading levels.

 Q (Mike Armstrong, Arkansas Game
 and Fish): I appreciated your com-
 ments on the important role that the
 DNR personnel can play in risk
 communication.  Please comment on
 what role the Minnesota DNR has in
 your process for establishing fish
 consumption advisories. How well
 have they received what you're doing?
 What has been the economic impact of
 your advisories on the recreation
fishing industry in Minnesota?

 Dr. Shubat:
     I started with the program the
 year that we took out the short-term
 consumption, and I got so many calls
 from resort owners saying "you're
 killing us."  Then we did a lot of work
 with them, traveling to the groups. We
 worked with the Office of Tourism to
 develop a specialized brochure for
 short-term consumers, a simply, easy-
 to-use piece that was not too scary. In
 the succeeding years, I haven't re-
 ceived any calls from resort owners.
 Things have gotten better since we've
 broadened the kind of advice that we
 give, the different tools that we have
 to communicate.  DNR, Health, and
 Pollution Control work collaboratively
 to work out the advisories.

 Q (Alan Stern, New Jersey Depart-
 ment of Environmental Protection):
 Regarding tuna, what considerations
 were there within state government in
 terms of the implications of this and in
 terms of national policy ?

 Dr. Shubat:
     The group most impacted by this
 is our State Department of Agricul-
 ture. They are responsible for carry-
 ing out inspection, etc.—for interpret-
 ing FDA action limits. They did
 contribute to the brochure. We've
talked about it at length with them
 over the years. Our food inspection
people are satisfied.

      National Forum on Mercury in Fish
                     Q (Bruce Mintz, U.S. EPA, Headquar-
                     ters): Do you try to characterize the
                     risk associated with the contaminant?
                     Do you say that if you exceed the
                     guidance it's unsafe, or do you indicate
                     that if you exceed the guidance it
                     doesn't necessarily mean you're going
                     to experience harmful effects?

                     Dr. Shubat:
                          We try to do the latter, but I'm
                     sure we fail in communicating that to
                     most people. I recommend picking up
                     the Lake Superior Fish Advisory. It's
                     our best example.  Its language was
                     crafted by the Great Lakes Advisory
                     Task Force, and a big part of the
                     advisory was how to communicate the
                     wide range of responses that the
                     human has to contaminants and how
                     that relates back to the advisory.
                     Development of Risk-Based
                     Fish Consumption Guidelines in

                     Dr. Randall Manning, Georgia Depart-
                     ment of Environmental Protection
Q (Gale Carlson, Missouri Department of
Health): Why did you choose 1 in 10,000
as the [risk] cutoff level?

Dr. Manning:
     I'll give you two reasons. One is
strictly a practical issue.  If you look at
detection limits that are available out there
for a lot of chemicals in fish tissue, when
you look at 10'6 risk and  10'5 and do back
calculations, with 10'6 you get into trouble
with a lot of the detection limits. With 10'5,
it is less of a problem. After working with
the system and looking at the numbers, and
presenting some mock-ups, I knew that if
we didn't go with 104 it would be killed
from the beginning. If we look at the
numbers and toxicity and carcinogenicity
and think about conservativeness of the
procedures, it's better than not doing it.
Managing and Communicating
Mercury Risks in Arkansas

Dr. Kent Thorton, FTN Associates

No questions

                 National Forum on
                    Mercury in Fish
  Day Three: September 29, 19y4
 State  Assistance Needs
      Rick Hoffmann asked the states
      represented in the audience to
      discuss their respective assistance
needs. The responses of the states are
presented in this section.

Stow Evans, Arkansas Department of

     Stan Evans briefly discussed the
Southern States Mercury Task Force and
its activities. He then listed a number of
ways in which the federal government
can assist state agencies in investigating
the mercury problem. The  "federal
assistance needs" include (1) a federal
coordinator or point of contact for
coordination of state and regional
studies; (2) a bulletin board or similar
depository for exchanging information;
(3) studies on fish sampling/subsam-
pling to reduce the amount  of tissue for
analyses and also holding time studies;
(4) deposition estimates and a deposition
monitoring network (revive NAAP for
mercury guidance); (5) tissue standards
for methylmercury, water standards for
methylmercury, and current tissue
standards from NRCC; (6) round robin
programs for sediment tissue and water
samples, including QA checks with state
participation; (7) financial support for
regional mercury task force efforts by
the states; (8) financial support for
outreach activities to reach impacted
segments of the public; (9) source
studies applicable to the southern United
States, including the role of southern
bottomland hardwood wetlands;
(10) continued dialogue between FDA
and EPA to achieve greater consensus
on risk assessment issues; and (11) alter-
native fish management programs for
impacted fisheries.

NOTE:  The Southern States Mercury
Task Force is composed of Alabama,
Arkansas, Florida, Georgia, Louisiana,
Mississippi, New Mexico, North Caro-
lina, Oklahoma, South Carolina, and
Jim Blumenstock, New Jersey Depart-
ment of Health

     We're still formulating a multi-
regional approach. First meeting next
week. We are in our infancy, and being
here the past couple of days has cer-
tainly been very helpful to hear how
other states are addressing concerns.
Participating states are Delaware,
Maryland, Pennsylvania, New Jersey,
New York, and Connecticut. We have
invited participants from health agen-
cies, environmental protection and
conservation agencies, and departments
of agriculture. We've had a very good
response. Fish safety, food safety will
be represented.

Kirk Wiles, Texas Department of

     I applaud EPA for the guidance
documents they've developed. There

                                                                 National Forum on Mercury in Fish
                     has been a lot of response from
                     government in answering the ques-
                     tions laid out at the Pittsburgh meet-
                     ing.  At this point we need to go a step
                     further. As I sit and listen to the
                     regional approaches being developed,
                     I'm a bit concerned.  The docu-
                     ments—Volumes  1 and 2—are useful,
                     but they will need to be changed. I
                     propose that a national forum be
                     developed to discuss and implement
                     changes in the volumes as they come
                     out and as they become antiquated.  It
                     could be necessary for a national
                     forum to look at each individual
                     volume and propose changes to it that
                     would be of usefulness to all of the
                     regions of the country.  For instance,
                     if you look at the  information pre-
                     sented  here on the use of the Monte
                     Carlo approach to risk assessment,
                     there seems to be  good acceptance
                     from some states. But if you look at
                     Volume 2, it's not going to be in-
                     cluded in there. The techniques and
                     technology will be changing in the
                     next few years. If we approach it on a
                     four- or five-region basis, I don't
                                            think it's
                    _________^__   going to
                                             solve the
                                            We could
                                             evolve the
                                             volumes into
                                             a useful,
                    ———^———^———    working,
                                             and chang-
                     ing document.  In doing so we could
                     receive input from industry, states,
                     user groups, and federal agencies. We
                     need a national forum to discuss and
                     recommend changes to those manuals.
                     There is obviously usefulness in a
                     regional approach. But the question
                     here is national in scope, not regional
                     in nature.

                     Rita Schoney,  U.S. EPA, Headquarters
                          There are some national efforts
                     that are under way, for example, the
                     Report to Congress, which is an interof-
                     fice, Agency-wide effort. There are
a. .. we've got to reach a good
balance between those risks
and the health benefits that
people gain from eating fish.w
other nationwide efforts. And there is a
meeting next week of a EPA-wide
Mercury Task Force.

John Hesse, Michigan Department of
Public Health
     We've had a Great Lakes Task
Force in place since 1985, but we
haven't recognized mercury as a major
contaminant problem in the Great Lakes
waters.  We've used PCBs as our
primary focus.  Now that we focus more
on mercury, especially in our inland
waters, we recognize that we don't have
good background-level measurements of
what kind of exposure has  occurred or is
occurring in our population in Michigan.
We're just gearing up to look at hair
levels. We have historic studies using
blood, but we'd like to get a better feel
for our general-population mercury
levels in hair so we can see how close
we might be to whatever threshold level
is determined.  We're looking now at a
10- to 20-ppm level as the threshold
level of concern, based on  the Iraq and
Japan studies. We're looking forward to
the Seychelle Island results. As a
reviewer of the first two volumes of the
EPA guidance documents, I'm looking
forward to seeing a more complete
health risk/benefit analysis. As we
tighten our advisories, we've got to
reach a good balance between those
risks and the health benefits that people
gain from eating fish. If we overlook
the health benefits, we may be doing the
public a disservice.

Jerry Pollock,  California EPA
     When we come out with a fish
advisory, it's very difficult to frame
what the benefits are.  It's also difficult
to put it into perspective as to what else
people should eat. There are a limited
number of protein sources out there, so
if you are recommending that people
decrease their consumption of seafood
then you are essentially recommending
that they increase their consumption of
some other protein source. And that
may carry some risks with it, too. We

Conference Proceedings
need an expanded database on exposure
to chemicals in these other food sources.
We can't ignore the associated risk of
increased consumption of saturated fats,
etc. I'm hoping that future documents
will put that in a tangible way.  Right
now it's very abstract.  A big uncer-
tainty I have is whether when I recom-
mend decreased consumption offish,
they actually carry a greater risk because
they increase their consumption of other
foods. We need a greater level of
certainty.  Our recommendations could
have a serious impact on people if they
change their diet as a result of an
advisory.  I need a greater amount of
insurance in my own heart.

Pat Carey, Minnesota Pollution
Control Agency

     I want to thank EPA for efforts in
scoping out and addressing solutions to
the mercury problem. Martha Keating
has been invaluable to us in coordinating
our efforts as a state and through the
Great Lakes Initiatives as well.  I hope
EPA continues to get the time to work on
this issue both on a regional and national
level.  If the Southern States Task Force
or any other groups that are out there
would want to tie into our particular
workgroup, please contact Angela
Bandemear at Region 5, Air Division.

Russell Isaac, Massachusetts Depart-
ment of Environmental Protection
     The issue is too large to manage in
isolation. The trade-offs must be consid-
ered to the extent that they can be. I urge
EPA to consider any financial support to
the Island studies. Our suspicion is that
our mercury is from our fallout. If that is
in fact true, it does suggest some things
we might do for going to low-mercury
fuels.  Clearly, local conditions make a
big difference in many cases.  Whether
the chemical erosion of local geology is
aggravated, acid precipitation is also a
major consideration. There are a lot of
scientific questions on sources, but if
we're ever going to go beyond managing
risk and actually try to do something
about reducing the problem, those are
obviously some of the questions that
need to be answered. Thanks for the

Greg Cramer, U.S. Food and Drug

     In response to a previous  question,
the Seychelle Islands studies have been
receiving financial support from NIEHS
and from FDA..  As people have talked
about regional activities and Stan
identified the needs for national data-
bases,  one of the things that came to my
mind is that developing a national
database on hair levels would be very
valuable as we scope out and try to
describe the problem using first point
estimates to describe the level of mer-
cury exposure. As Monte Carlo simula-
tions come along, we see those numbers
characterizing potential exposures sort
of backing off as we take into account
some of the different distributions
instead of just assuming simple point
estimates. The corroboration with hair
levels would help us to describe the
extent of the national problem.

Alan Stern, New Jersey Department of
Environmental Protection
     I want to add to Jim Blumen-
stock's comment regarding our interest
in a regional approach.  In that respect, I
would like to invite the southern re-
gional group to get in contact with us.
They already have a head start so we
can find out what sort of things they
have been able to do and where their
thinking is.

Jim Hanlon, U.S. EPA, Headquarters
     Let rne respond to the well-
thought-out comments in terms of where
we're at and where we should be going
in the next few year.  This arena is
different from an EPA standpoint. It's
not rule making. We do not anticipate
any federal regulations that deal with the
fish contamination/consumption area. It
is particularly useful that where we are

      National Forum on Mercury in Fish
                      at now is based on a dialogue that the
                      Agency has carried out over the last 5
                      years with states and other customers in
                      this arena. It's a great idea that on a
                      regional basis states be in contact with
                      each other. It's easy to spot areas where
                      fish advisories run up on one state
                      border, then don't continue on the map.
                      States need ongoing dialogue with each
                      other to improve decision making and
                      public communication.
                          It also is advisable that the federal
                      government continue to get its act
                      together (EPA, FDA, and other part-
                      ners).  We're moving in that direction
                      and plan to continue. At a similar
                      meeting a year ago, there were about
                      175 folks talking about PCB contamina-
                      tion in fish tissue (attendance was
                      limited by space).  The turnout here is
                      overwhelming. The question is, rather
                      than try to identify another fish contami-
                      nant next year, recognizing the dynamic
                      nature of this part of the business that
                      we're in, given the ongoing island
                      studies, given the forthcoming Volumes
                      3 and 4 for risk management and
                      communication, given the developing
                      positions and advice from regional and
                      state task forces, doesn't it make sense
                      for the federal government to sponsor a
                      dialogue like this every 12 to 18 months
                      to sort of check hi and see where we are
                      with it?  We will follow up as soon as
                      we can hi terms of the identified federal
                      points of contact, bulletin boards, etc. I
                      think it is invaluable to get the people
                      who are dealing with the issues on a
                      day-to-day basis to work in the same
                      place for a couple of days and do some
                      face-to-face coordination and communi-
cation. If you think that's a good idea,
we can take that back and put it in our
work plans. We are looking into 1995
and 1996 work plans. If you think this
kind of ongoing dialogue makes sense,
it's something we could respond to.
     EPA can only handle so many
questions from the 50 states and tribes.
In all respects these are national issues,
and if there is a platform of understand-
ing or knowledge of where the other
states are at or where the federal govern-
ment agencies are at, I think it could
only put us all in a better position to
answer those tough questions over the
phone: "Is it  safe to fish?" "What do I
do?" "What's your best advice?" To
the extent that we can be better in-
formed when  answering questions to the
public, the better we'll be fulfilling our
mission to the general public.

RickHoffmann, U.S. EPA, Headquarters

     The AFS meeting generated a list
of activities that the states said they
would like to see.  We took that back
and formulated it into a federal action
plan, which to a certain degree
sounded more grandiose  than it
actually was. It was sort of a work
plan for our group and it prompted a
lot of discussions among the other
agencies.  In a similar vein, when we
get this type  of information and
perhaps recommendations from the
other regional task forces and so forth,
we'll try to put them together and sort
them into different categories of
activities and then find some type of
mechanism for distributing that.

                 National Forum on
                    Mercury in Fish
Mercury in Fish  Tissue Projects
May  1995 Status Report
U.S. Environmental Protection Agency, Office of Water, Washington, DC
NOTE: Because the planning of the
Mercury Project has evolved since the
discussion of the project in September,
we have substituted a status report
current as of May 1995.

     Mercury Issue—Environmental
mercury contamination may pose human
health and ecological problems about
which there is still limited regional and
national understanding. The potential
adverse effects of chemical contami-
nants in fish is a recurrent Agency
concern; it is directly related to such
Clean Water Act responsibilities as
water quality standards, surface water
toxics, and EPA efforts to ensure that
waters of the U.S. are "fishable" and
"swimmable," etc.
     Significant quantities of environ-
mental mercury cycle through air,  water,
and solid phases of the global environ-
ment. Mercury is important because the
most toxic form, methylmercury,
accumulates in aquatic life. Public
concern stems from the tendency of
methylmercury to bioaccumulate in fish
tissue up to a million times or more
above concentrations found in the water
column. Although the degree of
bioaccumulation can vary from water-
shed to watershed due to various factors,
the problem appears to be a widespread
problem posing national concern. As of
September 1994, 34 states had issued
fish consumption advisories for one or
more waterbodies; several states had
issued statewide advisories.
     During 1995 and 1996, EPA will
be working with other agencies in a
cooperative effort to assemble a nation-
wide database on mercury in fish
tissues. The mercury project has two
parts: collection of mercury data and
database development. Mercury Data
Collection: During 1995, we intend to
identify and assemble data on mercury
concentrations in fish tissues throughout
the United States. As part of this effort
EPA will be working with state and
federal agencies and other groups that
have collected mercury data. Database:
EPA intends to eventually develop a fish
tissue database as a major part of the
STORET modernization efforts.
Planned Activities
    The overall objective of this
project in 1995 is to assemble and
review data on the nature and nation-
wide extent of mercury contamination in
fish. To accomplish this, the following
approach is envisioned. It will be
modified depending on data quality and

Mercury Data Collection—
Preliminary Test

    The first part of the data collection
effort will use EPA's EMAP stratified
sampling grid to specify sampling
locations within each state. If adequate
state-collected data exist for the speci-

      National Forum on Mercury in Fish
                     fied locations, the EMAP methodology
                     will be used to evaluate mercury con-
                     centrations on a nationwide basis.
                     Preliminary Review of Mercury Data

                          Another component of the project
                     is to make a qualitative evaluation of
                     the nature and extent of state-collected
                     mercury data. This review will be used
                     to derive an approximate sense of
                     existing data and determine what
                     additional work might be needed.
                     Working through EPA's regional
                     offices, we hope to assemble reports of
                     state fish mercury data and evaluate
                     data availability by state, region,
                     ecoregions, etc. "Snapshots" of the
                     data may be compiled to convey
                     approximate estimates of tissue con-
                     centrations, determine number and
                     frequency of mercury samples, etc.
                     Wherever available,  statistics such as a
                     mean, median,  range, variance, etc.
                     will be reviewed.
                     Mercury Data—Full-Scale Collection
                     and Storage

                          The long-term objective of the
                     study is to assemble a comprehensive
                     database of mercury fish tissue concen-
                     trations. This data collection will be a
                     multi-year effort. EPA's Office of
                     Science and Technology within the
                     Office of Water has already established
                     a National Fish Tissue Data Repository
                     (NFTDR). The objectives of the
                     NFTDR are to simplify data exchange
                     by improving the comparability and
                     integrity offish tissue data, encourage
                     greater regional and interstate coopera-
                     tion, and assist states in their data
                     collection efforts by providing ongoing
                     technical assistance. The NFTDR
currently is part of EPA's ODES
database; unfortunately, the ODES
database has not evolved into a widely
used database.
     As part of this effort, EPA intends
to modify its existing National Fish
Tissue Data Repository (NFTDR) and
incorporate it as a major prototype
during the modernization (Phase III) of
the STORET database. During 1996, we
intend to convert the NFTDR to a
STORET-based fish tissue database.
The primary benefit of including the
NFTDR as a subset of STORET is that
one "platform" will be able to store both
water quality data and biological data,
such as fish tissue information. Existing
data sets would be able to easily migrate
to the new STORET system when it is
completed in early 1997. The use of real
fish tissue data during prototype devel-
opment should help us identify needed
data fields, test the data structure, etc.

Further Information
     EPA recognizes that the mercury
study and database development project
will involve a large number of states.
Typically several different agencies
within the same state gather and analyze
fish tissue data. If you and/or your
agency might be interested in more
information about the project as it
develops, please send your name and
mailing address to the following ad-
dress. Information about the projects
will be sent out periodically.

National Mercury Fish Tissue Project
Risk Assessment andManagementBranch
Rick Hoffman (4305)
401 M Street, SW
Washington, DC 20460

          National Forum on
Mercury in Fish
Mercury Deposition and the Activities
of the Clean Air Act of 1990
Martha Keating
Office of Air Quality Planning and Standards, USEPA, Research Triangle Park, North Carolina

                                                                National Forum on Mercury in Fish
                    Clean  Air Act of 1990
                   ••Considerable debate  in Congress over mercury emissions
                    and sources led to a number of provisions that specifically
                    address mercury.
                   ••Congress recognized the scientific uncertainties about
                    whether mercury is a  "local" or "global" pollutant, and also
                    discussed the implications of requiring additional control
                    technologies, particularly for utilities.
                   >-As a result, a number of Reports to Congress were
                    mandated as well as consideration of mercury in other
                   Mercury Study Report to
                     National emissions inventory (snapshot ~ 1990)
                    > Exposure assessment- potential for public health and
                     ecological risk from inhalation and food chain
                     - Long-range transport analysis
                     -Local impact analysis
                       - Human health benchmarks
                       - Wildlife criterion for trophic level 4
                     Risk characterization
                     Risk management
                     -Control technologies and costs

Conference Proceedings
               Mercury Sources and Emissions
                 Numerous source categories were examined,
                 included area sources,
                •Biggest emitters are coal-fired utilities,
                 medical and municipal waste combustors,
                 chlor-alkali plants, copper and lead smelters,
                 cement manufacturers and secondary
                 mercury production.
                -These sources, in the aggregate, comprise
                 98 percent of the inventory.,,.

                 But, what about impacts?
                Some Factors Affecting Exposure
                Magnitude of emissions on a per-facility basis.
                Proximity of the facility to a water body.
                Stack parameters, including stack height and
                exit velocity.
                • Speciation of mercury emissions (greatly
                affects predicted deposition).
                • Fish consumption patterns of the exposed

                                                            National Forum on Mercury in Fish
                  Risk Management
                   Regulatory decisions combine the results of the risk
                   characterization with an assessment of control
                   options, and other nonrisk analyses (e.g, benefits
                   The mercury study will address control technologies
                   and their costs for certain source categories.
                   It will also describe other provisions of the CM and
                   how they relate to mercury control, as well as
                   specific State and Federal actions that are also being
                  Important 112  Provisions for
                  Mercury Sources
                  • Utility Study - will include regulatory
                  recommendations for utility boilers.
                 - Section 112(c)(6) - requires EPA to list and regulate
                  sources accounting for 90 percent of the emissions
                 " Great Waters Program - allows EPA to promulgate
                  any further control measures or standards to protect
                  public health and the environment.
                 • Urban Area Source Program - may identify mercury
                  as one of 30 priority pollutants in urban air.

Conference Proceedings
                  Regulatory Activities Already
                 > Emission standards for municipal waste combutors.
                 »• Emission standards for medical waste incinerators.
                 > Advanced Notice of Proposed Rulemaking: lesser quantity
                  emission rate for mercury.
                 »Mercury source categories scheduled for regulation
                  -Chlor-alkali plants
                  -Commercial/Industrial boilers
                  -Primary lead smelters
                  -Primary copper smelters
                  -Portland cement kilns
                  -Sewage sludge incinerators
                  -Lime manufacturers	


                National Forum on
                   Mercury in Fish
Great  Lakes 'Virtual  Elimination'
Frank Anscombe
Policy Analyst, U.S. Environmental Protection Agency, Great Lakes National Program Office,
Chicago, Illinois

I   am filling in for Jim Giattina,
    Deputy Director of EPA's Great
    Lakes Program Office in Chicago.
One reason that I regret that Jim could
not be here is that he recently called
up the Defense Department, which is
apparently the dominant supplier of
mercury within the United States, and
asked whether DOD could postpone
further sales, pending consideration of
their environmental ramifications.
Apparently, folks concerned about
mercury contamination have for years
been noting that the federal govern-
ment supplies the stuff. But, to my
knowledge, no one before Jim dialed
11 digits,  reached the right people,
and asked, "Could you suspend this
practice?"  They have, temporarily.
This fall our office will support an
EPA task  force to consider what
recommendations to provide our
colleagues in DOD.
     While I am sorry Jim cannot hear
your recommendations, I will certainly
pass along any you offer.  We want to
    •  If you just happened to own
      11.5 million pounds of elemen-
      tal mercury,  what would you do
      with it? This is actually a
      serious question because the
      simple fact is that as American
      citizens we do own this much
      mercury through our govern-
   •  As our society continues to
      reduce its use of mercury, what
      should we do with the resulting
    We came across the federal sales
of mercury issue while working on a
project with the somewhat obscure
name "Virtual Elimination." I will talk
about this project and more broadly
about the efficacy of public policies
governing mercury, which is what the
project is really about.  While not
directly part of the Administration's
Common Sense Initiative, our effort is
asking common sense questions, such
as: Should the federal government
supply a hazardous commodity that it
thereafter regulates from smokestacks
and pipes? We share with the Common
Sense Initiaitive a holistic perspective—a
whole systems approach—to environ-
mental protection. As we view mercury
this way, from cradle to  grave, we can
consider whether the parts make an
efficient whole, which is cleaner,
smarter, cheaper.

     With this introduction, I am
organizing my remarks into:
    • Mercury's environmental context
    • Mercury's socioeconomic context
    • Potential policy options
    • What might our Virtual Elimi-
      nation project suggest about

                                                                    National Forum on Mercury in Fish
                      Mercury's Environmental

                          The problem seems to be that
                      during this century humankind has been
                      busy, beavering away, extracting and
                      making much more use of mercury than
                      ever before, and then not disposing of
                      this mercury in an environmentally kind
                      way.  The result is that some bit of it
                      converts to methylmercury, which
                      magnifies in aquatic food webs, posing
                      risks to Americans who rely on fish in
                      their diets.
                          When we look back at mercury
                      history as recorded in peat bog cores
                      and in sediment cores, we find that
                      mercury used to be much less present in
                      the upper Midwest:
                         •  A peat bog near Duluth, Minne-
                           sota, has revealed that before
                           1900, mercury deposition was
                           about one-tenth of what it
                           became by mid-century (1935 to
                           1980); since 1980, levels have
                           fallen by a third.
                         •  This trend is very much in
                           keeping with recent dated sedi-
                           ment cores from the Great Lakes,
                           which show that mercury levels
                           were extremely low before 1900,
                           surged greatly thereafter, peaking
                           between 1950 and 1970, and have
                           fallen back a bit since.
                         While bogs and sediment indicate
                     the general environmental abundance of
                     mercury, risks to human health are
                     posed by an apparently very small
                     percentage of this abundance—meth-
                     ylmercury in fish. Canadian researchers
                     have tracked methylmercury in several
                     Great Lakes fish species for a decade or
                     more.  Their results generally mirror
                     the bog and sediment core trends, in that
                     they show a gradual decline in recent
                     years in methylmercury levels in lake
                     trout and smelt across the Great Lakes.
                         Yet, in recent years, public health
                     authorities in Michigan, Wisconsin, and
                     Minnesota have issued fish advisories
                     for thousands of lakes.  Are new adviso-
                     ries reflective of a worsening problem
                     with mercury or of a growing awareness
                     of a long-standing problem? An answer
 is complicated by the fact that many
 factors seem to be involved in methyl-
 mercury accumulation, including
 differences in chemistry between water
 bodies, differences between fish species
 in vulnerability to mercury, and geo-
 graphic variation in the distribution of
 mercury and underlying geology. And
 there are few data on year-to-year trends
 in fish. If levels in the Minnesota peat
 bog core and in Great Lakes fish and
 sediments are indicative of a broad
 national decline in methylmercury levels
 in recent years, this is welcome.
     It might be, however, that this
 trend is a local anomaly, reflective of a
 drastic reduction of mercury discharges
 to the  Great Lakes since the 1970s,
 when chloralkali plants spewed mercury
 into Lake Erie, closing fisheries there.
 It might well be that atmospheric levels
 of mercury over the upper Midwest
 continue to increase, such that mercury
 levels  are still increasing in waters that
 receive mercury only via the atmo-
     Whatever the recent national trend,
 what is clear is that mercury levels in
 many fish species across many waters
 are near risk-based thresholds. There-
 fore, it is prudent public policy to
 increase the margin of safety for wildlife
 and for human health by further reduc-
 ing methylmercury levels in fish.
     This leads to the central question
 facing decisionmakers: How to do this?
     Clearly the principal current
 pathway for dissemination of mercury  is
 the atmosphere.  While I regret missing
 Prof. Fitzgerald's  presentation on
 Tuesday, I believe that he and his
 colleagues are finding that mercury
 levels in the atmosphere of the northern
 hemisphere and in the world's oceans
 are in the ballpark of three times those
 of 100 years ago.  They are also finding
 that roughly one-half of anthropogenic
 emissions enter the global atmospheric
 reservoir of mercury, whereas the other
 half is deposited near its source.
     So the key to reducing methylmer-
cury in fish seems to be reducing
mercury emissions to the atmosphere,
both locally and internationally.

Conference Proceedings
     It is further my understanding that
the processes that convert mercury
forms to methylmercury are both
complex and insufficiently understood.
As a result, we must consider that all
emissions of mercury will potentially
yield methylmercury.  If at some point
scientific understanding of methylation
is able to narrow our target from all
mercury emissions to just some, this
will be a welcome development, allow-
ing decisionmakers to focus on a more
narrowly defined problem.
     Other key aspects to the environ-
mental context of mercury are that it is
both mobile and nondegradable.
    • Mercury is mobile. It is a
      volatile fluid at room tempera-
      tures and reaches a gaseous state
      at 300 °C. Any mercury released
      to the environment can be a
      "grasshopper pollutant," volatiliz-
      ing from land to be redeposited
      and revolatilized again.  When  it
      enters water, it can be converted
      to methylmercury.
    • Mercury does not decay. If the
      volume of mercury that mankind
      uses and releases exceeds the
      earth's capacity to rebury it, then
      mercury levels will rise in the
      atmosphere and the earth's
      waters. In general, this rise has
      been going on for the last 150
      years, as evidenced in bog and
      sediment cores. The world's
      continuing use of mercury might
      bequeath an inheritance to future
      generations  of rising mercury
      levels in fish across the globe.
      The only way to stop this out-
      come—to break the mercury
      cycle— is to convert unused
      mercury and mercury waste to  a
       nonsoluble form, such as its
       sulfide phase or cinnabar, and
       dispose of this, perhaps by
 Socioeconomic Context

      At this point, I will turn to the
 socioeconomic context surrounding
mercury, which is a useful commodity
traded worldwide. Mercury usage in
both the United States and Europe has
significantly declined in recent years.'
Between 1980 and 1992, U.S. consump-
tion fell about 70 percent. The most
notable part of this decline in mercury
usage was in batteries. In 1980, batter-
ies accounted for 40 percent of mercury
demand; in 1992, battery making used
2 percent of domestic consumption.
Many other mercury uses have declined,
including measuring instruments (80
percent decrease) and chemicals and
allied products (95 percent decline),
because of the phaseout of mercury in
paints and reduced use in the chloralkali
     Today, the leading domestic use
categories are chlorine and caustic soda
(32 percent of consumption); wiring and
switches (10 percent); followed by
electric lighting, measuring instruments,
dental supplies, and laboratory use.
     This use reduction is welcome
news from an environmental  point of
view. But substitution away  from.
mercury has been followed by a surge in
exports from the United States to other
parts of the globe, including China,
India, South America, and South Africa.
     I mentioned earlier that the U.S.
government auctions mercury from
holdings that are now regarded as
unneeded by the Departments of
Defense and Energy. In terms of our
domestic  demand, these federal sales
are a big deal! In 1993, they were
about 625,000 pounds or two-thirds of
domestic  demand. The remaining
stock of 11.5 million pounds is
equivalent to 10 more years of domes-
tic consumption.
     A few more economic facts about
    • The going auction price is $1 a
      pound or thereabouts.  This low
      commodity price is probably
      attributable to the combination of
      declining use in the United States
      and Europe, coupled with the
      availability of government-owned
      stocks not merely in the United
      States, but from the nations of the

                                                                     National Forum on Mercury in Fish
                            former USSR, which are making
                            all sorts of materials available.
                          •  Because of this low price, mining
                            of mercury for profit is much
                            reduced. The largest mercury
                            mine in the world is owned by a
                            government (Spain's), so it might
                            not be exposed to profitability
                          •  There is no active mercury mine
                            in the United States, though there
                            are activities that yield mercury
                            as an incidental, recoverable by-
                            product, notably gold mining and
                            zinc operations and, to a smaller
                            extent, copper and natural gas
                          •  Mercury's cheap price makes the
                            recovery or recycling of mercury
                            from products that contain it
                            financially unattractive. Recy-
                            cling is normally done because of
                            governmental regulations.
                          •  This low price might favor
                            remaining uses because alterna-
                            tive products or processes might
                            be uncompetitive with mercury
                            on a cost basis.
                          •  However, many remaining
                            deliberate uses of mercury
                            undoubtedly confer benefits to
                            society.  Fluorescent bulbs save
                            energy and money. Many
                            valuable measuring instruments
                            use mercury.
                     Policy Options

                          Given these economic and environ-
                     mental contexts, what policy responses
                     could be considered? Emissions of
                     mercury are the key, and Martha Keating
                     has just mentioned the sectors that seem
                     to be the primary emitters: utilities,
                     municipal waste combustors, medical
                     waste combustors, chloralkali plants, lead
                     and copper smelting, among others. EPA
                     has recently proposed or will shortly
                     propose regulations governing both
                     municipal and medical waste combus-
                     tors. These requirements are not aimed
                     particularly at mercury, but at a host of
      I understand that there will be
 forthcoming air regulations for other
 leading mercury emission sectors.  It is
 fair to say that utilities and smelters
 cannot readily substitute away from
 mercury since their mercury releases are
 purely incidental to their businesses.
 Their best opportunities to reduce
 mercury emissions might be in capturing
 mercury from their inputs, rather than in
 product substitution, as was possible
 with paint or batteries.
      The newest technology for chlorine
 and caustic soda production does not use
 mercury. Most chloralkali plants still
 using mercury are older facilities.
 Switching to the new technology is very
 capital-intensive and might not be eco-
 nomically feasible for some firms.
Virtual Elimination Project

     At this point, I would like to apply
some lessons from our ongoing Virtual
Elimination project. This project is an
effort to assess the sources of mercury
and the regulatory structure surrounding
uses and releases, from cradle to grave,
so as to see whether governments can
improve their policies to spur ongoing
reductions—beyond compliance—in the
use and release of mercury.
     "Beyond compliance" is a key
concept and is perhaps best illustrated by
what is going on in the hazardous waste
business. The costs of responsibly
dealing with hazardous waste are leading
generators to waste minimization so as
to save money. They are not merely
complying with RCRA;  they are going
"beyond compliance" to prevent pollu-
tion. As a result, some waste disposal
firms face slowing demand for their
services, but waste minimization is good
for the environment.
     The phrase virtual elimination is
taken from a U.S. policy statement on
the Great Lakes that is 16 years old. It
refers to persistent toxicants like mercury.
     Our project is a work in progress.
Yet, we have some initial observations
and I will highlight a few:

Conference Proceedings
      Some states have banned the
      deliberate use of mercury in
      certain products. These bans
      have generally happened where
      alternatives are available or when
      mercury use has been unimpor-
      tant to society.
      Banning is a very strong preven-
      tion approach, which has yielded
      the largest reductions in mercury
      use in this country (dropping
      mercury from paints and batter-
      ies). When one or a few states
      such as Minnesota, Wisconsin,
      Michigan, and New York have
      instituted  product bans, there has
      been a ripple effect, whereby
      manufacturers then provide
      mercury-free alternatives across
      the Nation.
      Many remaining uses are prob-
      ably not amenable to bans. So in
      addition, some states are trying
      recycling  requirements for
      manufacturers. And I have heard
      that some are considering taxes
      on mercury uses to provide an
      economic incentive for innova-
      tion away from mercury use.
      Such preventive measures are a
      powerful supplement to federal
      environmental approaches, which
      tend to focus on regulating
      pollutants at their point of release
      or disposal.
      Many regulatory requirements
      levied at the release/disposal
      point are not conveyed back to
      those who initially decide to use
      mercury in a consumer product.
      Costs imposed on incinerators do
      not necessarily encourage mer-
      cury prevention by a manufac-
      turer who sells this product to a
      consumer, who hi turn sends the
      product to an incinerator.
      Many consumers are unaware of
      the mercury content in products
      at the moment of their purchasing
      As said before, the federal
      government auctions a lot of
      mercury.  We are looking into the
      desirability of ending the federal
      government's participation in
      this.  This would probably not
      have a discernible impact on
      price,, given the world surplus, or
      on domestic use. But ending
      these auctions might be grounds
      for asking other governments that
      sell mercury to likewise curtail
      their sales. Ending sales would
      exemplify "thinking globally,
      acting locally" and would send a
      clear message within our society
      and to the world that this country
      urges the prevention of mercury
      use and release.
      There might not be an exit plan
      within the United States for mer-
      cury, other than export. Sweden
      has apparently banned recycling
      of mercury on environmental
      grounds.  The United States may
      want to consider doing the same
      in this country for all but essen-
      tial remaining uses of mercury.
      EPA is respectful that much
      further progress in preventing
      pollution does not lie with
      governments at all, but depends
      on the expertise and innovatory
      energy of the private sector.
      Many industries are doing good
      things to  reduce their use of
      mercury. A major light manufac-
      turer is striving to develop a
      mercury-free fluorescent bulb.
      Chloralkali plants are doing more
      recovery  of mercury. Our
      progress as a society in heading
      toward final prevention of
      mercury, virtual elimination, rests
      on such efforts.

     I will sum up:
    •  Mercury use and release lead to
      an environmental problem—
      methylmercury hi fish.
    •  Emissions are the most important
      way that mercury contamination
      is distributed.
    •  World releases of mercury might
      increase because of the world's

                                                                     National Forum on Mercury in Fish
                            growing appetite for fossil fuels
                            to maintain the economic growth
                            unleashed by the collapse of
                            Our nation's use of mercury
                            seems to be declining and releases
                            might be as well.
                            But methylmercury levels in fish
                            are too high, and it is prudent to
                            strive for further progress toward
                            the holy grail of virtual elimina-
                            However, the abundance of mer-
                            cury and its relative cheapness
                            favor increased international use
                            and mercury-based technologies.
                            Bans on deliberate use of mercury
                            in products when alternatives are
                            available have been successful.
                            In addition, this nation might be
                            well served to consider an exit
                            plan for its growing surplus of
                            mercury, which could entail
                            returning mercury to  the earth
                            whence it came, in a controlled
                            Continued international attention
                            to mercury seems important,
       given the global spread of
       mercury contamination through
       the atmosphere.
    •  Ending federal sales of mercury
       might be a clear message to send
       to the international community.
     The Clinton Administration has
emphasized the reinvention of govern-
ment.  This philosophy entails invest-
ing in  prevention rather than cure.  It
entails being guided by facts and
mission, rather than blindly adhering
to administrative rules of conve-
nience. It implies working with all
sectors of society, steering private/
public partnerships toward common
goals,  like virtual elimination of
mercury. Our project is in keeping
with this spirit of reinvention.
     Everything I have said is prelude
to the next speaker, who represents a
state that has been in the forefront of a
seismic shift toward mercury prevention
and the reinvention of environmental
protection.  Pat Carey will discuss some
of the common-sense prevention
measures that Minnesota has taken to
reduce its mercury problem.

                  National Forum on
                    Mercury in Fish
 Minnesota Mercury
Patrick F. Carey
Principal Planner, Minnesota Pollution Control Agency, Hazardous Waste Division
St. Paul, Minnesota

     The Minnesota Pollution Control
     Agency (MPCA) estimates total
     anthropogenic mercury emissions,
excluding those resulting from latex
paint volatilization, to be about 7,700 lb/
year (White and Jackson 1992). The
MPCA finds that roughly half of these
mercury emissions are a result of energy
production (i.e., burning coal and other
fossil fuels that contain mercury) and
half result from the disposal of products
that are purposefully manufactured with
mercury (e.g., thermostats, fluorescent
lamps, dry-cell batteries, and thermom-
eters). Interestingly, water point-source
discharges account for only about 30 lb/
year of mercury.
Minnesota Strategy for
Mercury Emissions from
Energy Production

     To address Minnesota's mercury
emissions from energy production, the
MPCA is intent on developing a long-
term state strategy based on federal
action resulting from two Clean Air
Act Studies, the Utility Air Toxics
Study and the National Mercury
Study, which are scheduled to be
completed over the course of the next
2 years. Until federal action occurs,
the MPCA will continue efforts to
work with the Minnesota Public
Utilities Commission to incorporate
the environmental costs of mercury
releases into utilities' energy planning
process and continue to promote
energy conservation, efficiency, and
alternatives to fossil fuels.
Minnesota Strategy for
Mercury Emissions from
Mercury Product Disposal!

     To address Minnesota's mercury
emissions from the disposal of mercury-
bearing products, the Minnesota State
Legislature has passed a number of mer-
cury product laws over the last several
years. The following briefly summa-
rizes these laws, followed by a brief de-
scription of efforts to implement these

Minnesota. Mercury Product LAWS

     Minnesota's mercury product laws
can be grouped into the following five

Product Labeling/Notification

     These laws include (1) a require-
ment that thermostats, switches, ther-
mometers, and scientific/medically
related equipment that contain mercury
be labeled to indicate the products
contain mercury and must be disposed

      National Forum on Mercury in Fish
                      of properly; (2) elemental mercury user/
                      handler notification requirements; and
                      (3) responsibilities for mercury lamp
                      sellers and replacement contractors to
                      inform the buyer/user of proper mercury

                      Mandated Collection Requirements

                           These laws include provisions
                      requiring (1) contractors removing
                      thermostats, switches, thermometers,
                      appliances, or medical or scientific
                      instruments from service to properly
                      manage removed products;  (2) thermo-
                      stat manufacturers to provide incentives
                      to induce purchasers to properly manage
                      spent thermostats; (3) Northern States
                      Power (NSP), a major utility hi Minne-
                      sota, to collect fluorescent lamps from
                      households and small businesses located
                      in NSP service areas; (4) battery
                      manufacturers to  ensure that mercuric
                      oxide batteries from businesses are
                      managed properly; and (5) lamps
                      removed from state-owned  buildings to
                      be recycled.

                      Disposal Bans
                           These laws prohibit businesses and
                      homeowners from disposing of elemen-
                      tal mercury, mercury-containing lamps,
                      thermostats, thermometers,  switches,
                      appliances, and medical or scientific
                      instruments in the solid waste stream or
                      sewer system.

                      Sales/Distribution Bans
                           These laws (1) prohibit the sale
                      of mercuric oxide batteries, fungi-
                      cides, and games, toys, and wearing
                      apparel containing elemental mercury
                      and (2) prohibit  medical facilities
                      from routinely distributing mercury
                      fever thermometers.

                      Content Restrictions

                           These laws  mandate the reduction
                      and/or  elimination of mercury content in
                      certain dry-cell batteries, packaging,
                      pigments, and dyes.
Implementation Activities/Strategy

     Minnesota, in general, has taken a
two-pronged approach to implementing
the mercury product laws and other
efforts for reducing mercury emissions
in Minnesota. The approach includes
(1) mercury product collection activi-
ties, the short-term solution/effort, and
(2) source reduction/elimination activi-
ties, the long-term solution/effort. The
following briefly summarizes activities
under both approaches.

Product Collection Activities

     The MPCA's short-term goal is to
establish accessible and economical
collection systems for business and
household consumers to recycle mer-
cury products properly.  To achieve this
goal, the MPCA established several
operating principles. First, don't
recreate the wheel. Work to tap into
systems that already exist for other
wastes in both the public sector (county/
municipal recycling programs and
household hazardous waste programs)
and the private sector (contractors,
reverse distribution, retailers). Second,
create partnerships by identifying
potential public/private  sector partners,
understanding the impediments to
achieving their participation (regulatory
and economic), and removing unneces-
sary regulatory and economic impedi-
     By applying these principles over
the last couple years, collection systems
for a number of mercury products have
been established with public and private
sector involvement:
    1. Thermostats. Honeywell, a major
      thermostat manufacturer, has
      implemented a free take-back
      program for-business and house-
      hold consumers,  which includes a
      free reverse distribution system
      (contractor to wholesaler to
      Honeywell) and a prepaid mailer
      system for those  who replace
      their own thermostats without a
      contractor. Under the program,
      Honeywell accepts any mercury

Conference Proceedings
      thermostat, even those manufac-
      tured by a different company.
    2. Switches.  A Minnesota switch
      manufacturer is  interested in
      establishing a take-back program
      similar to the Honeywell program.
    3. Button Batteries. Proex, a major
      photo-developing chain store in
      Minnesota, will soon implement a
      free counter-top  drop box pro-
    4. Mercury-Containing Lamps.
      Three lamp recycling facilities
      now exist in Minnesota. One of
      these recyclers, Recyclights, has
      installed a superior distiller in
      order to recycle other mercury
      products.  There is a system of
      about 50 transporters/contractors
      in Minnesota. Northern States
      Power is working to meet its
      mandate to be involved in the
      collection of lamps from
      homeowners and small businesses
      in NSP service areas.
    5. Household Hazardous Waste Col-
      lection Programs. All 87 Minne-
      sota counties have established
      household hazardous waste collec-
      tion programs. Many of these
      programs will accept mercury
      products.  One of the programs,
      the Western Lake Superior Sani-
      tary District (WLSSD) in the
      Duluth, Minnesota,  region, has
      implemented the "Merc Alert"
      Program, an aggressive program
      for collecting mercury products
      from citizens in the district.
    6. Scrap and Auto Salvage Yards.
      The MPCA is working with scrap
      and auto salvage yards to employ
      best management practices to
      remove and recycle mercury-
      containing items from autos and
      other scrap.

 Source Reduction/Elimination
     The MPCA's long-term goal is to
 source-reduce or eliminate mercury hi
 products to the extent possible. To
 achieve this goal, a number of activities
have been or will be conducted iin
    1. LA. Gear Mercury Switch
      Shoes.  Minnesota's 1994 sales
      ban for mercury-containing
      wearing apparel not only reduces
      and eventually eliminates this
      one source of mercury from the
      waste stream, but it also
      (1) sends a message to product
      manufacturers to "design for the
      environment" and consider the
      appropriateness of using mercury
      in products and (2) makes
      consumers aware of the concerns
      related to mercury-containing
      products in order to help them
      make purchasing decisions and
      meinage these products appropri-
      ately after use.
    2. Mercury in Products Study.  In
      1995, the MPCA will conduct a
      study of all products that contain
      mercury to identify mercury
      source reduction and elimination
      opportunities.  Legislation
      governing mercury in products
      might result from the findings of
      the study. Conducting the study
      will involve a substantial dialog
      with product manufacturers to
      define problems/solutions. The
      MPCA will also investigate
      innovative incentive-based
      controls for mercury use reduc-
      tions (e.g., use tax, deposit/
      refund, others).
    3. WLSSD''s Efforts with Dentists.
      The Western Lake  Superior
      Sanitary District (WLSSD) has
      worked aggressively with
      dentists sewering to the WLSSD
      wastewater treatment plant to
      reduce mercury discharges
      resulting from the sewering of
      dental amalgam.
    4. Hennepin County Collection
      Programs. The municipal waste
      combustor of the Hennepin
      Energy Resource Corporation
      (HERC) is located in downtown
      Minneapolis, Minnesota.  The
      HERC facility, in conjunction
      with Hennepin County, has

      National Forum on Mercury in Fish
                            established aggressive front-end
                            separation programs for mercury
                            products to control emissions.
                            After implementing these
                            programs, HERC's average
                            overall mercury emission
                            concentration was reduced by
                            over two-thirds.

White, D.M., and A.M. Jackson.  1992.
     Technical work paper on mercury
     emissions from waste combustors.
     Prepared for Air Quality Division,
     Minnesota Pollution Control
     Agency, St. Paul, MN.

Conference Proceedings
                             Estimated Atmospheric
                    Mercury  Emissions in Minnesota, 1990
                         Annual Total about 7,700 pounds per year
                      (2,000 Ib, 26%)
       Dentists, Hospitals, Labs (<1%) •
                Cremation (<1%)
            Petroleum Refining (1%)-^x'1
        General Industrial Activity (3%r   >
         Fluorescent Lamps (300 Ib, 4%r
                    Sewage Sludge
                    (400 Ib, 5%)
     (500 Ib, 7%)
                           Municipal Solid Waste
                              Landfill volatilization
                              (880 Ib, 11%)
            Wood (600 Ib, 8%)

      Natural Gas (600 Ib, 8%)
Medical Waste (500 Ib, 7%)
                            Categories in Bold'have the highest degree of confidence;
                              additional data are needed for the other categories.
                                                                     MPCA 12/92
                    Estimated Mercury Emissions
                                   by Source
                          General Industrial Activit;
                            Fluorescent Lamp:
                        Sludge Combustioi
               Medical Waste Combustion
                         MSW Combustion
                                                       Natural Gas
                                            1— Petroleum Refining

                                          National Forum on Mercury in Fish
50 Percent Emissions from Energy


 • Develop state strategy based on federal
   action from Clean Air Act studies; utility
   air toxics study and mercury study
 • Incorporate into energy plans the
   environmental costs of mercury releases
 • Promote energy conservation, efficiency
   and fossil-fuel alternatives
    50 Percent Emissions from
        Mercury in Products
                      • Mercury product laws
                      • Reduction activities/strategies

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              Minnesota Mercury Product Laws
                  •  Labeling/notification requirements
                  •  Mandated collection requirements
                  •  Disposal bains
                  •  Sale/distribution bans
Minnesota Mercury Product Laws
  • Labeling requirements for certain
    mercury-containing products:
      • Thermostats
      • Switches
      • Thermometers
      • Appliances
      • Lamps
      • Medical/scientific instruments

                                            National Forum on Mercury in Fish
Minnesota Mercury Product Laws

 •  Elemental mercury user/handler
   notification requirements
     • Seller provide MSDS
     • Purchaser signs certification of
       responsible use/disposal
     • Lamp sellers and lamp-replacement
       contractors inform buyer of mercury
       management requirements
Minnesota Mercury Product Laws

 •  Mandated collection requirements
     • Contractors removing thermostats,
        switches, thermometers, appliances, or
        medical or scientific instruments from
        service shall manage products.
     • Thermostat manufacturers must provide
        incentives to induce purchasers to
        properly manage spent thermostats.

Conference Proceedings
Minnesota Mercury Product Laws
Mandated collection requirements continued
  • Northern States Power to collect fluorescent
     lamps from households and small businesses
     in their service areas
  • Battery manufacturers to ensure proper
     management of mercuric oxide batteries from
  • Recycle lamps removed from state-owned
                Minnesota Mercury Product Laws
               Disposal bans
                • Elemental mercury
                • Mercury-containing lamps
                • Thermostats
                • Medical or scientific instruments

                                            National Forum on Mercury in Fish
Minnesota Mercury Product Lews

 • Sale/distribution bans

     • Mercuric oxide batteries
     • Games and toys containing elemental
     • Wearing apparel containing elemental
     • Medical facilities from routinely
        distributing mercury fever thermometers
Minnesota Mercury Product Laws

 •  Content restrictions
     • Mandated reduction and elimination of
        mercury content in dry-cell batteries
     • Mandated reduction and elimination of
        mercury content in packaging

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Implementation Activities/Strategies

  • Two-pronged strategy:
      • Product collection - short-term strategy
      • Source reduction/elimination - long-term

Product Collection Activities
                 Goal:  To establish accessible and
                 economical collection systems for business
                 and household consumers

                             National Forum on Mercury in Fish

• "Don't recreate the wheel"
    • Public Sector
      • County/municipal recycling programs
      • Household hazardous waste programs
    • Private Sector
      • Contractors
      • Reverse-distribution
      • Retailers
       Principles Continued
Create partnerships
  • Identify potential partners
  • Understand impediments to participation
     (regulatory and economic)
  • Remove unnecessary impediments
   • Pilot project for Special Hazardous Waste
   • Work with manufacturers, retailers to
     sponsor system

Conference Proceedings
               Snap Shot of Collection Systems

                • Thermostats
                    • Honeywell thermostat take-back program
                      « Free reverse distribution system
                      • Prepaid mailer for DIYers
                      • Any mercury thermostat accepted
                Snap Shot of Collection Systems

                • Switches
                    • Minnesota switch manufacturer interested
                       in establishing take-back program
                • Button Batteries
                    • Proex to implement free couritertop drop
                       box program

                                            National Forum on Mercury in Fish
Snap Shot of Collection Systems

   •  Mercury-containing lamps
       • Three, lamp-recycling facilities
          (250 to $1 per four-foot lamp)
       • Fifty transporters/contractors
       • NSP working to establish collection
Snap Shot of Collection Systems

•  Household Hazardous Waste Collection
    • All 87 Minnesota counties involved
    • Most will accept mercury products
    • Western Lake Superior Sanitary District's
       "Merc Alert" Program

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Source Reduction/Elimination Activities
   • Strategies for Reducing Mercury in Minnesota
   • Mercury in Products Report
       • Dialogue with manufacturers to define
       • Innovative, incentive-based controls for
          mercury-use reductions
       • Two phases - legislative recommendations by
          spring 1996
           Source Reduction/Elimination Activities
                   • WLSSD's efforts with dentists
                   • L.A. Gear mercury-switch shoes
                   • Federal mercury stockpiles


                 National Forum on
  Day Three: September 29,  1994
                    Mercury in Fish
 Questions  and  Discussion
       After each speaker's presentation,
       an opportunity for questions and
       answers was provided. Time
 was also allotted for a group discussion/
 question-and-answer session.
National Mercury Study
Dr. Jerry Stober, U.S. EPA, Region 4,
and Dr. Steve Paulson, U.S. EPA,

Q (Luanne Williams, North Carolina
Department of Environmental Health
and Natural Resources): Who do we
contact first for a listing of state adviso-

Mr. Hoffmann:
     Jeff Bigler is the contact. We've
updated on an annual basis. We get
most data from 305(b) reports. Because
it changes so much, we try to do interim
updates. Contact our office. We have
money set aside for the next fiscal year
to update that database.

Q (Deedee Kathman, Aquatic Resources
Center): Steve, do you have any plans
for EMAP to do marine coastal waters?

Dr. Paulson:
     Right now in terms of this study
we have not thrown that out. But the
estuaries program has been collecting
mercury data in fish, and those data will
be available. We haven't specifically
thought about how to incorporate the
estuaries into a concept like this, of
using existing data, but that's a good

Rob Reash, American Electric Power: I
would like to suggest that, for the Great
Lakes region, there exists a very sizable
database going back to the mid-1970s
for several standardized locations. For
four of the Great Lakes that the Ontario
Fish Contaminant Section has been
monitoring, you can call  them and get
raw data from their standardized
locations.  If you want to look at tempo-
ral trends and mercury residues in
various fish species that you do not
ignore this long-term database and
incorporate these historical data into
the data collected in future years.

David Sager, Texas Parks and Wildlife
Department:  There are a lot more data
than just the 305(b) report and EMAP
data out there. There are long-term-
sampling programs that are not associ-
ated with EPA that I think need to be
incorporated into this.  You need to
contact all of the agencies, not just those
major programs that report to EPA.

Q (Jim Wiener, National Biological
Survey): One of the problems that has
compromised the value of a number of
existing databases is the lack of rigor

       National Forum on Mercury in Fish
                      and the quality of the data.  There was
                      some mention made of quality assur-
                      ance.  Can you give more information
                      on that?

                      Dr. Stober:
                          That is a problem that we recog-
                      nize we are going to run into because
                      each state has its own protocol right
                      now and, even though there is a guid-
                      ance document out there, it takes time to
                      change over.  Given the level and the
                      amount of data existing hi the states on
                      mercury, the challenge is to try to do
                      something valid with existing databases,
                      then move into some standard protocol
                      that cuts across all states so that we do
                      generate a rigorous database that moves
                      forward from  here.
                      Dr. Paulson:
                          I'd add that while that is a real
                      concern, I think one of the values of
                      trying to look at data from across a
                      fairly broad spatial perspective is that
                      many of the patterns seem to show up
                      if they are there. (At least this is true
                      for other parameters that we've looked
                      at where there was similar concern
                      about the quality of individual mea-
                      surements and difference in protocols
                      across state lines, etc.) I do not want to
                      minimize that concern in trying to
                      move to a more standardized approach.
                      But I think first crack is that we'll see
                      some of the patterns—maybe not all of
                      them, and not defined at the level that
                      we'd like—but it will be useful to get
                      that started.

                      Mercury Deposition and the
                      Activities of the Clean Air Act
                      of 1990
                      Martha Keating, U.S. EPA

                      Q (Rob Reash, American Electric
                      Power):  Utilities are gearing up for
                      compliance with phase 1 and 2 SO2
                      emissions. Given the fact that there will
                      be a lot of technology changes, how will
                      that incremental control of mercury by
                      these new technologies be factored into
your report for utilities that are switch-
ing to fuel gas desulfurization technolo-
gies, which will result in some incre-
mental decrease in mercury emissions?

Ms. Keating:
     That will be in the Utility Study
Report. There have been a number of
projections about what utilities are
going to do—whether they're scrub,
whether they're going to fuel switch,
what they are going to do to meet the
acid rain provisions.  All that will be
factored into the Utility Study for
mercury reductions. They are doing a
1990 base scenario and a 2010 projec-
tion to incorporate the acid rain technol-

Q (Larry Fink, South Florida Water
Management District): Your work is so
important, I am ecstatic about it.  Did
you attempt to mass balance the mer-
cury flow through the economy so that
you can validate emissions estimates,
less what's stored and/or in usable
forms,  versus what's being used on an
annual basis?

Ms. Keating:
     No.  A lot of the mercury that is
used hi industry doesn't really become a
problem until the product is disposed of.

Q (Larry Fink, South Florida Water
Management District): Did you look at
area sources that have been created as
a result of historical reasons?

Ms. Keating:
     No, there is no natural emissions
inventory.  When we did a long-range
transport model, we factored in a
2-ng/m3 background.

Q (Larry Fink, South Florida Water
Management District): Did you cali-
brate and validate?

Ms. Keating:
     We are comparing our model
results to measured data. There are not
a lot of data out there. There are not
enough data to validate our model.

 Conference Proceedings
 Q (Larry Fink, South Florida Water
 Management District):  Can you use
 data from Canada?

 Ms. Keating:
      No, we didn't feel it was complete

 Q (Larry Fink, South Florida Water
 Management District):  Regarding
 pollution prevention and risk manage-
 ment options, is this part of this exercise?

 Ms. Keating:
      Pollution prevention options were
 considered when we looked at control
 options for a number of source catego-
 ries. However, the data on both the
 efficiency and costs of these types of
 measures are very limited (for example,
 battery recycling programs for munici-
 pal waste combustors). Another ex-
 ample of where we looked at pollution
 prevention was switching from the
 mercury cell process to a diaphragm
 process for chlor-alkali plants. The
 utility study will look at fuel switching
 and other options for utility boilers.

 Glenn Rice, U.S. EPA:  I have been
 working on this study.  This is not a
 site-specific study. It did not include a
 lot of background levels.  It did try to
 come up with rigorously defined param-
 eters that were used in the model.  We
 spent a lot of time focusing on param-
 eters.  We hoped it will be a resource to
 the states who want to do site-specific
Great Lakes "Virtual
Elimination" Project
Frank Anscombe, U.S. EPA, Great
Lakes National Program Office

Dr. William Fitzgerald, University of
Connecticut:  I would like to clear up
any misconceptions about Factor 3 and
the changes that I spoke about on
Monday. I presented a modern and a
pre-modern view, and they are based on
 average values and relatively simple
 mass balances.  The Factor 3 and the
 other types of predictions should really
 be used as guides provided with a
 framework and a way of focusing
 research. I would caution you not to
 use a Factor 3 as a fact, but as a guide.

 Mr. Anscombe:
      I agree. I find it useful as a
 general guide, while appreciating that it
 cannot be a precise measure.
 Minnesota Mercury Reduction
 Pat Carey, Minnesota Pollution
 Control Agency

 Q (Jim Wiener, National Biological Sur-
 vey): I applaud what you 're doing to
 reduce emissions. There are a number
 of examples of human activities that can
 result in increased localized exposure of
populations to methylmercury.  There
 are human activities that don't neces-
 sarily affect the supply of mercury to the
 environment; for example, the creation
 of new reservoirs, which is turning out
 to be quite an issue in Canada, one that
greatly elevates the methylmercury ac-
cumulation in fish. What, if any, role do
you envision for regulatory agencies in
actions of this type that may influence
exposure to methylmercury?

Mr. Carey:
     We would treat it as another
potential source and do an assessment
of whether it was something we should
be concerned about. We would deter-
mine how much of a contribution it is to
the overall problem and try to develop
corresponding solutions to deal with
that. A lot of our efforts up to this point
have been primarily focused on those
major sources.

Pom Shubat, Minnesota Department of
Public Health:  There are a series of
reservoirs in Northern Minnesota, and
the utility's permit that allows them to

                                                                National Forum on Mercury in Fish
*Using TCLP regulations,
you can essentially dispose
of pure elemental mercury
as a nonhazardous waste in
a nonregulated landfill.*
                    operate was held up because they were
                    required to submit a plan for monitor-
                    ing mercury and required to do some
                    experimental work in their reservoir
Final Group Discussion/

Q (Cindy Gilmour, Philadelphia Acad-
emy of Science): Regarding TCLP
regulations for disposal of mercury as
hazardous waste, the TCLP extraction
procedures don't extract elemental
                mercury out of
                hazardous waste.
                Using TCLP regula-
                tions, you can essen-
                tially dispose of pure
                elemental mercury as
                a nonhazardous
                waste in a
                nonregulated landfill.
<                I was wondering if
                anyone from EPA can
comment on that glitch in TCLP regula-
                     Mr. Hoffmann:
                         I'm not aware of anyone here
                     who can address that. I think that this
                     type of issue, where you have the
                     potential for conflicting goals and
                     mandates, is one of the reasons that
                     the Mercury Task Force is being
                     established. For example, if you
                     establish a policy to encourage the
                     collection and disposal of household
                     hazardous waste, what conflicts, if
                     any, might result?

                     Cindy Gilmour, Philadelphia Academy
                     of Science:  There is a very common
impression among hazardous waste
contractors in the mid-Atlantic states
that people think elemental mercury is
neutral and it is not soluble, not volatile.

Martha Keating, U.S. EPA:  The
Office of Solid Waste and Emergency
Response had come out with their
proposal on how to deal with fluores-
cent light bulbs—whether we should
exclude them from hazardous waste
regulations or recycle them. One of
the issues raised during comments on
that rule has been that there was not
an effective procedure for mercury.
The Office of Solid Waste is going to
be pushing research in that area.

Q (Greg Cramer, U.S. Food and Drug
Administration): Regarding the emis-
sions from wood sources, where are they
coming from and what are you doing to
control them?

Mr. Carey:
     The wood  sources are residential
burning.  Our air quality folks are
looking at this component of the
emissions. They are considering
certain avenues to pursue.

Ms. Keating:
     On a national level there is a 1
emission factor for wood burning. We
didn't use it in the national inventory
because it was based on only one test of
one type of wood.  There are not a lot of
emissions data from wood stoves. We
also did not have a good handle on how
many wood stoves there were in the
country. We estimated about 12 mil-
lion, but it was a guess. Because of
these uncertainties, a national estimate
of mercury from woodstoves was not
included in the inventory.

                  National Forum on
Speakers'  Biographies
Frank Anscombe

     Mr. Anscombe is a policy analyst
with EPA's Great Lakes Program Office
in Chicago, Illinois. He received a B.A.
from Yale College and an M.A. in pub-
lic policy from the University of Chi-
cago, concentrating in economic aspects
of government regulation. Prior to j oin-
ing EPA, Mr. Anscombe served as a
supply officer of a submarine and of a
shipbuilding program for the Navy.
With the Great Lakes Program, he has
led development of a Report to Con-
gress and is presently contributing to
the Virtual Elimination project, which
aims to promote public policies that
would spur prevention of bioaccumula-
tive pollutants.
Thomas D. Atkeson, Ph.D.

     After 9 years with the Florida
Department of Health as Chief of the
Environmental Epidemiology Program,
where he was involved in a wide
variety of environmental contaminants
issues, Dr. Atkeson joined the Depart-
ment of Environmental Protection in
June 1992. His responsibilities are to
coordinate Florida's response to the
finding of high levels of mercury in fish
and wildlife. His primary efforts are
devoted to planning a long-term
research program aimed at defining the
causes of mercury contamination in
Florida and coordinating the activities
of a variety of local, state, federal, and
private agencies in pursuit of those
research objectives.
     Dr. Atkeson's background is in
zoology and wildlife biology, with
education at Auburn University and the
University of Georgia.
Nicolas S. Bloom

     Mr. Bloom is Chief Scientist and
Vice President of Frontier Geosciences
Inc., a small environmental research
corporation located in Seattle, Washing-
     Mr. Bloom received his B.S. in
chemistry from the University of
Washington and his M.S. in oceanogra-
phy from the University of Connecticut.
He worked for 9 years at the Battelle
Pacific Northwest Marine Research
Laboratory, where he developed ultra-
clean sample handling techniques and
novel methods for the chemical specia-
tion of trace metals. In 1991,
Mr. Bloom and Ms. Sharon Goldblatt
established Frontier Geosciences, where
he and a staff of nine persons investigate
the speciation and biogeochemistry of
trace metals in the environment.
P. Michael Bolger, Ph.D.,

     Dr. Bolger is the Chief of the
Contaminaints Standards Monitoring and
Program Branch in the Center for Food
Safety and Applied Nutrition of the U.S.
Food and Drug Administration (FDA) in
Washington, DC.
     Dr. B.olger received his B.S. in
biology from Villanova University and
his Ph.D. in physiology and biophysics
from Georgetown University. After a
2-year postdoctoral position with the
Department of Physiology in the
Georgetown University Medical Center,
Dr. Bolger became a staff fellow in
toxicology with the Bureau of Foods in
the FDA. Upon completion of the staff
fellowship, he accepted a position as a
toxicologist with the Contaminants

      National Forum on Mercury in Fish
                     branch at FDA. Over the last decade, he
                     has been involved in a number of hazard/
                     risk assessments of food contaminants,
                     including methylmercury. Dr. Bolgeris
                     board-certified as a toxicologist by the
                     American Board of Toxicology. He is
                     currently Chief of the Contaminants
                     Standards Monitoring and Programs
                     Branch, which is responsible for the
                     monitoring and hazard/risk assessment
                     of environmental contaminants in the
                     food supply.
for private animal research contract
firms in the Washington, DC, area.
During this time, as a study veterinarian,
Dr. Cicmanec conducted a subchronic
reproductive research study involving the
effects of PCBs on a large group of
rhesus monkeys.  Dr. Cicmanec is a
Diplomate of the American College of
Laboratory Animal Medicine. In
addition to his veterinary training, he
received an M.S. from the University of
Michigan Medical School.
                     Pat Carey

                          Mr. Carey is a Principal Planner
                     for the Minnesota Pollution Control
                     Agency (MPCA), Hazardous Waste
                     Division, Program Development Section.
                          Mr. Carey received his B.S. in
                     government/political science from St.
                     Johns University in Minnesota. He
                     joined the MPCA in 1984.  Over the past
                     decade, Mr. Carey has been involved in
                     developing waste management policies
                     and programs in Minnesota for a number
                     of special wastes, including used oil, oil
                     filters, vehicle batteries, dry-cell batter-
                     ies, used tires, PCB ballasts and capaci-
                     tors, and mercury-containing products.
                     He is currently a member of the MPCA's
                     Mercury Task Force, a multimedia effort
                     focused on developing strategies for
                     reducing mercury emissions.
                     John L. Cicmanec, Ph.D.

                          Dr. Cicmanec is a Veterinary
                     Medical Officer of the Systemic Toxi-
                     cants Assessment Branch in the Environ-
                     mental Criteria Assessment Office of
                     EPA's Office of Research and Develop-
                     ment in Cincinnati, Ohio.
                          Dr. Cicmanec is a research veteri-
                     narian who presently works as a risk
                     assessor. Prior to joining the staff of the
                     Environmental Criteria Assessment
                     Office, he directed the operation of the
                     research animal facility of EPA in
                     Cincinnati. Prior to the 8 years that he
                     has spent with EPA, he spent 16 years as
                     a clinical veterinarian and study director
Thomas W. Clarkson, Ph.D.,
M.D., h.c.

     Dr. Clarkson is a graduate of the
University of Manchester, where he
received his B.Sc. and Ph.D. degrees.
He accepted a position at the University
of Rochester in 1957 as a research
fellow and, except for a 3-year period in
research institutes abroad, he has been a
member of the medical faculty at the
University of Rochester ever since.
Dr. Clarkson is currently Professor and
Chairman of the Department of Environ-
mental Medicine.
     His research work is directed
toward understanding the toxicology of
heavy metals, especially mercury and its
compounds.  His interest is in the
pathways and mechanisms of disposition
of toxic metals in the body. An under-
standing at the cellular level of how
metals cross diffusion barriers in the
body will give insight into the mecha-
nisms of toxic action, on factors that
influence their toxicity, and might lead
to the development of effective methods
of removing metals from the body.
Charles F. Facemire, Ph.D.

     Dr. Facemire is the Senior Environ-
mental Contaminants Specialist for the
Southeast Region (Region 4) of the U.S.
Fish and Wildlife Service in Atlanta,
     Dr. Facemire received a B.S. in
wildlife  science from New Mexico State
University, an M.S. in biology from the

Conference Proceedings
University of Illinois at Champaign-
Urbana, and a Ph.D. in zoology from
Miami University in Oxford, Ohio. After
a year as an Assistant Professor at South
Dakota State University, where he con-
ducted research on the impacts of agri-
cultural chemicals on migratory birds,
Dr. Facemire accepted a position with the
Vero Beach (Florida) Field Office of the
U.S. Fish and Wildlife Service. Prior to
accepting his current position, he served
as a Senior Staff Biologist with the Divi-
sion of Environmental Contaminants,
Arlington, Virginia.
William F. Fitzgerald, Ph.D.

     Dr. Fitzgerald is a Professor of
Marine Geochemistry in the Department
of Marine Sciences at the University of
Connecticut. He has been at the Univer-
sity since 1971.
     Dr. Fitzgerald obtained a B.S. in
chemistry from Boston College, an M.S.
in chemistry from the College of the
Holy Cross, and a Ph.D. in chemical
oceanography that was awarded jointly
by the Massachusetts Institute of Tech-
nology and the Woods Hole Oceano-
graphic Institution in 1970.
     Professor Fitzgerald's general
research interests are in atmospheric and
marine chemistry, with particular
emphasis on global biogeochemical
cycles of trace  metals and the environ-
mental impact resulting from metal
emissions associated with human en-
deavors. His current and long-term
research activities have been focused on
mercury in the  environment, and he has
published more than 50 professional
papers dealing with various aspects of
the biogeochemical cycling of mercury.
     At present, Professor Fitzgerald is
investigating significant aspects of the
biogeochemical behavior and fate of
mercury in the atmosphere and in natural
waters. This research is multifaceted
and often interdisciplinary and involves
international collaboration. For ex-
ample, these pursuits include a U.S./
French cooperative examination of the
historical record of interhemispheric
cycling and air-water exchange of
mercury over mid-continental lacustrine
regions as part of a multidisciplinary
program studying the pathways and
processes regulating the aquatic bio-
geochemistry of mercury in the temper-
ate zone; this work complements
ongoing investigations exploring the
aquatic biogeochemistry of mercury in
coastal and open ocean environments.
This research is supported by grants
from the National Science Foundation,
from the NATO Scientific Affaires
Division:  Collaborative Research Grants
Programme, from the Wisconsin Depart-
ment of Natural Resources, from the
Electric Power Research Institute, and
from the Research Foundation of the
University of Connecticut.
Cindy C. Gilmour, Ph.D.

     Dr. Grilmour is Assistant Curator at
the Academy of Natural Sciences'
Estuarine Research Center in southern
Maryland. She received her B.A. in
biochemistry from Cornell University
and her Ph.D. in marine, estuarine, and
environmental science from the Univer-
sity of Maryland. She joined the Acad-
emy after 3 years of postdoctoral work
with Professor Ralph Mitchell at
Harvard University. Dr. Gilmour's
research focuses on microbial mercury
methylation in fresh waters and estuaries
and on the microbial ecology of Chesa-
peake Bay,
Rick Irloiffmann

     Mr. Hoffmann organized the
National Forum on Mercury in Fish. He
is an environmental scientist in EPA's
Risk Assessment and Management
Branch. The Branch is located in the
Office of Science and Technology within
the Office of Water.  The Branch is
responsible for directing sediment
contamination programs and evaluating
risks associated with chemical contami-
nants in fish.  Mr. Hoffmann works on
fish contamination issues.

       National Forum on Mercury in Fish
                          Prior to his current position,
                     Mr. Hoffmann worked in EPA's San
                     Francisco region, where he held various
                     positions relating to water quality
                     planning and pollution control as well as
                     overall environmental impact assess-
                     ments. He has also worked for the
                     Hawaii State Department of Health.
                     Mr. Hoffmann received a B.A.  in
                     zoology from California State University
                     at San Diego and an M.P.H. from the
                     University of Hawaii's School of Public
                     Health, with an emphasis in environmen-
                     tal/occupational health.
                     James P. Hurley, Ph.D.

                          Dr. Hurley is a Chemical Limnolo-
                     gist with the Wisconsin Department of
                     Natural Resources, Bureau of Research.
                     He holds a joint appointment as an
                     Honorary Associate with the University
                     of Wisconsin-Madison Water Chemistry
                          Dr. Hurley received his B.S. in
                     chemistry and environmental analysis
                     from Nasson College and his M.S. and
                     Ph.D. from the University of Wisconsin
                     Water Chemistry Program. After a 2-
                     year postdoctoral position with the
                     Wisconsin Center for Limnology,
                     Dr. Hurley accepted his current position
                     with the Wisconsin Department of
                     Natural Resources. Over the past 6
                     years, he has worked with several
                     projects involving mercury cycling in the
                     environment.  He has participated in two
                     phases of the EPRI-sponsored Mercury
                     Cycling in Northern Temperate Lakes
                     Project and 3 years of the Wisconsin
                     DNR's Background Trace Metals in
                     Rivers study. He is currently involved in
                     those two projects as well as the trace
                     metals in tributaries phase of the EPA-
                     sponsored Lake Michigan Mass Balance
                     Martha Keating

                          Ms. Keating received her B.S.
                     from the University of New Hampshire
                     and her M.S. in environmental science
from the School of Public Health at the
University of North Carolina - Chapel
Hill. She was employed as a staff
scientist by Radian Corporation until
1988, when she joined the U.S. Environ-
mental Protection Agency. Ms. Keating
has worked extensively with state and
federal air toxics programs and is
currently the project lead for the
Agency's Mercury Study Report to
Randall O. Manning, Ph.D.,

     Dr. Manning is the Coordinator of
the Environmental Toxicology Program
in the Georgia Department of Natural
Resources, Environmental Protection
     Dr. Manning received his Ph.D.
from the University of Georgia (UGA),
College of Agriculture, where he studied
the toxicity and metabolism of mycotox-
ins. After a 2-year postdoctoral position
with the Interdepartmental Toxicology
Program at UGA, Dr. Manning became
an Assistant Research Scientist in the
Department of Pharmacology and
Toxicology at UGA, studying the
toxicity of volatile organic chemicals
and the development of physiologically-
based pharmacokinetic models for use in
risk assessment. Dr. Manning joined the
Georgia Environmental Protection
Division in 1991 and was certified as a
Diplomate of the American Board of
Toxicology in 1992. He is currently the
Coordinator of the Environmental
Toxicology Program, which is respon-
sible for providing the Division with
support in toxicology and hazard/risk
assessment. One focus of Dr. Manning's
work has been the development of a
systematic monitoring program for
contaminants in fish and improved fish
consumption advisories in Georgia.
Donald Porcella, Ph.D.

     Dr. Porcella is Project Manager,
Land and Water Resources Manage-

Conference Proceedings
ment, at the Electric Power Research
Institute (EPRI), Palo Alto, California.
     His current research activities at
EPRI include wetlands, carbon
mitigation and cycling, and the
biogeochemistry of selenium, arsenic,
and mercury. His previous positions
were at Tetra Tech, Inc., Utah State
University, the University of California
Sanitary Engineering Research
Laboratory, the Norwegian Water
Research Institute in Oslo as a Fulbright
Postdoctoral Fellow, and as a visiting
scientist at EPA's Environmental
Research Laboratory in Corvallis,
Oregon.  His previous research interests
included lake and reservoir modeling,
bioassays, eutrophication, lake and
watershed liming, and radioecology.
Dr. Porcella has written more than 140
technical papers and books, has served
on many advisory committees, and has
been a technical reviewer for profes-
sional journals. He received
his B.A. and M.A. in zoology and his
Ph.D. in environmental hearth science
from the University of California at
Robert £. Reinert, Ph.D.

     Dr. Reinert is a Professor of
Fisheries in the D.B. Warnell School of
Forest Resources at the University of
     Dr. Reinert received his B.S. in
biology from Ripon College in Wiscon-
sin and his M.S. and Ph.D. in fisheries
from the University of Michigan. He
worked on Great Lakes contaminant
problems for 9 years at the U.S. Fish
and Wildlife Service Great Lakes Fish
Laboratory in Ann Arbor, Michigan.
He then became the Unit Leader for the
Cooperative Fish and Wildlife Unit at
the University of Georgia, in Athens.
For the past 14 years Dr. Reinert has
been a faculty member of the D.B.
Warnell School of Forest Resources.
His main research interests are dynam-
ics of contaminants in aquatic systems,
development of biomarker techniques
for fish, and risk assessment.
Deborah Rice, Ph.D.

     Dr. Rice is a Research Scientist
with the Toxicology Research Division,
Health Protection Branch, Canadiaoi
Department of Health, where she has
worked for 18 years. During that time,
Dr. Rice has been involved in determina-
tion of behavioral toxicity produced by
developmental neurotoxicants such as
lead and methylmercury, using the
monkey as a model. Her research has
focused on study of complex learning
and memory, and assessment of sensory
system function.  She has served on the
National Institutes of Health Initial
Review Group (Study Section) for
Toxicology., as well as numerous ad hoc
committees for such agencies as the
Environmental Protection Agency and
the National Institutes of Environmental
Health Sciences.
     Dr. Rice received a B.S. in biologi-
cal sciences from the University of
California, Irvine, and a Ph.D. from the
University of Rochester.
Pamela J, Shubat, Ph.D.

     Dr. Shubat is an Environmental
Toxicologist with the Minnesota Depart-
ment of Health. She manages the
Community Environmental Health
Survey and Research program located in
Health Risk Assessment, Division of
Environmental Health.
     Dr. Shubat received her B.S in
biology from the University of Minne-
sota, Duluth, and conducted aquatic
toxicity tests for many years at the Envi-
ronmental Protection Agency's Environ-
mental Research Laboratory in Duluth.
She received her M.S. in fisheries and
wildlife from Oregon State University
and her Ph.D. in pharmacology and
toxicology from the University  of Ari-
zona. After a postdoctorate at Arizona,
Dr. Shubat took a research scientist po-
sition with the Minnesota Department of
Health in the area of risk assessment.
Dr. Shubat holds an adjunct appoint-
ment at the University of Minnesota,
where she lectures in risk assessment.

                                                                   National Forum on Mercury in Fish
                      Over the past 5 years, Dr. Shubat has
                      been responsible for the Minnesota Fish
                      Consumption Advisory program and has
                      been an active member of the Great
                      Lakes Sport Fish Advisory Task Force.
                      Alan Stern, Dr. P.H., D.A.B.T.

                          Dr. Stern received a bachelor's
                      degree in biology from the State Univer-
                      sity of New York at Stony Brook, a
                      master's degree in cellular and molecular
                      biology from Brandeis University, and a
                      doctorate in public health from Columbia
                      University. He is board-certified as a
                      toxicologist by the American Board of
                      Toxicology, adjunct assistant professor
                      in the Department of Environmental and
                      Community Medicine at the University
                      of Medicine and Dentistry of New
                      Jersey, and a Councilor of the Interna-
                      tional Society for Exposure Analysis.
                      After a brief stint with Region 2 of the
                      U.S. EPA, he was Chief Toxicologist in
                      the Environmental Health Services of
                      the New York  City Department of
                      Health for 9 years.  Since 1990 he has
                      been a Research Scientist in the Division
                      of Science and Research of the New
                     Jersey Department of Environmental
                     Protection, where he specializes in
                     human health risk and exposure assess-
                     ment. He is also a regular fish con-
                     Jerry Stober, Ph.D.

                          Dr. Stober is a Fisheries Scientist
                     with the U.S. Environmental Protection
                     Agency, Region 4, Environmental
                     Services Division, Ecological Support
                     Branch, located in Athens, Georgia.
                          Dr. Stober received his B.S. in
                     1960, M.S. in 1962, and Ph.D. in 1968
                     from Montana State University. He was
                     a Professor of Fisheries at the Fisheries
                     Research Institute, University of Wash-
                     ington, for 18 years, where he conducted
                     aquatic environmental research in
                     freshwater and estuarine systems. Since
                     joining EPA in 1986, Dr. Stober has been
                     involved in assessing bioaccumulative
 contaminants in fish and participating in
 the development of national guidance
 documents. Since 1992 he has been
 conducting a R-EMAP study of mercury
 biogeochemical cycling in the Everglades
 ecosystem designed to culminate in an
 ecological risk assessment
 Kent W. Thornton, Ph.D.

      Dr. Thornton is the Arkansas
 Mercury Task Force Coordinator and a
 Principal in FTN Associates, Ltd. in
 Little Rock, Arkansas.
      Dr. Thornton received his B.A. in
 zoology and his M.S. in water pollution
 limnology from the University of Iowa
 and his Ph.D. in systems ecology from
 Oklahoma State University. He spent a
 year as a Postdoctoral Fellow in the
 School of Electrical Engineering at
 Oklahoma State and a year as Assistant
 Professor in Biological Sciences at
 Bowling Green State University. For 7
 years, he conducted research on reservoir
 water quality with the U.S. Army
 Engineer Waterways Experiment Station
 in Vicksburg, Mississippi. Dr. Thornton
 has been a Principal with FTN for the
 past 13 years.  Over the past decade, he
 has been involved in EPA aquatic effects
 research, the NAPAP 1990 Integrated
 Assessment, ecological risk assessment,
 ecological restoration, and mercury
 impacts on the environment. He is
 currently serving as the Coordinator for
 the Arkansas Mercury Task Force.
Roberta F. White, Ph.D., ABPP

     Dr. White is Associate Professor of
Neurology and Environmental Health at
Boston University, Research Director of
the Boston Environmental Hazards
Center, and Director of Clinical
Neuropsychology at the Boston DVA
Medical Center and Boston University
Medical Center. She received her Ph.D.
in clinical psychology from Wayne State
University and did her postdoctoral
fellowship in neuropsychology at Boston
University School of Medicine, Depart-

Conference Proceedings
ment of Neurology. For the past 14
years, she has done research in behav-
ioral toxicology and test development
and validation. She also trains students
studying neuropsychology at the gradu-
ate and postgraduate levels and works
with patients who have primary neuro-
logic disorders.
James G. Wiener, Ph.D.

     Dr. Wiener is presently Leader of
the Section of Ecology at the National
Biological Survey's Fisheries Research
Center in LaCrosse, Wisconsin. The
Center does research on riverine and
aquatic ecology, ectotoxicology, and
habitat-restoration techniques for large
     Dr. Wiener has a B.S. in fish, and
wildlife biology from Iowa State Univer-
sity and a Ph.D. in zoology from the Oak
Ridge National Laboratory.  He held a
position as a field station leader with the
U.S. Fish and Wildlife Service, National
Fisheries Contaminant Research Center.
During the past two decades, he has been
studying the bioaccumulation and fate of
potentially toxic metals in freshwater
ecosystems, with emphasis on mercury
and cadmium.


                  National Forum on
 Selected EPA  Publications
J^Whe following listings are selected
  I  EPA publications related to
 M. chemical contaminants in fish.
These documents were prepared by
EPA's Office of Water as part of a
Federal Assistance Plan to help states
and other interested parties implement
fish consumption advisory programs.
Guidance for Assessing Chemical
Contaminant Data for Use in Fish
Advisories: Volume I:  Fish Sampling
and Analysis, EPA 823-R-93-002,
August 1993.
    This document provides detailed
    technical guidance on methods for
    sampling and analyzing chemicals
    in fish and shellfish tissues. It
    addresses monitoring strategies,
    selection of fish species and chemi-
    cal analytes, field and laboratory
    procedures, and approaches to data
Guidance for Assessing Chemical
Contaminant Data for Use in Fish
Advisories: Volume II: Risk Assess-
ment and Fish Consumption Limits,
EPA 823-B-94-004, June 1994.
    This volume provides detailed
    guidance on the development of
    risk-based fish consumption limits
    for fish. In addition to methods, the
    document offers specific toxicologi-
    cal information on 24 potential fish
Guidance for Assessing Chemical
Contaminant Data for Use in Fish
Advisories: Volume III: Risk Man-
agement (being developed in 1995).
Guidance for Assessing Chemical
Contaminant Data for Use in Fish
Advisories: Volume IV: Risk Com-
munication, EPA 823-R-95-001,
March 1995.
    The document begins with an
   overview of the risk communication
   process and its major components.
   Subsequent sections provide in-depth
   discussions of such topics as prob-
   lem analysis and program objectives,
   audience identification and needs
   assessment, communication strategy
   design and implementation, program
   evaluation, responding to public
   inquiries, and other topics. The
   discussions are illustrated frequently
   with "real life" examples drawn from
   numerous state or regional fish
Consumption Surveys for Fish and
Shellfish, A Review and Analysis of
Survey Methods, EPA 822-R-92-001,
February 1992.
   This document contains a critical
   analysis of methods used to deter-
   mine fish consumption rates of
   recreational and subsistence fishers,
   groups that might have the greatest
   potential for exposure to contami-
   nants in fish tissues.
Proceedings of the U.S. Environmental
Protection Agency's National Techni-
cal Workshop "PCBs in Fish Tissue,"
EPA 823-R-93-003, September 1993.
   This document summarizes the
   proceedings of the EPA-sponsored
   workshop held on May 10-11,1993,
   in Washington, DC.
To Order Copies: Mail, call, FAX, or
Email a request to:

EPA OW Resource Center (RC4100)
401 M Street, SW
Washington, DC 20460
Phone recording order: (202) 260-7786
FAX order: (202) 260-0386
Email: waterpubs@epamail.epa.gov

Include the publication title and EPA
publication number.


National  Forum on
          Mereury in  Fish
                                  September 27-29,1994
                                  New Orleans, Louisiana
                             Final  Agenda
Tuesday, September 27
7:30-8:30  Registration

8:30-8:55  Welcome and Introduction
          James A. Hanlon, U.S. EPA, Headquarters
          Rick Hoffmann, U.S. EPA, Headquarters


9:00-9:30  Biogeochemical Cycling of Mercury:  Global
          and Local Aspects
          Dr. William Fitzgerald
          University of Connecticut

9:30-10:00 Aquatic Biogeochemistry and Mercury
          Cycling Model
          Dr. Donald Porcella
          Electric Power Research Institute

10:00-10:30Mercury Methylation in Fresh Waters
          Dr. Cindy Gilmour
          Philadelphia Academy of Science


10:45-11:1 SConsiderations in the Analysis of Water and
          Fish for Mercury
          Mr. Nicolas Bloom
          Frontier Geoscience

11:15-12:OODiscussion/Question-and-Answer Session

12:00-1:30 LUNCH (on your own)

 1:30-2:00 Bioaccumulation of Mercury in Fish
          Dr. James Wiener
           U.S. Fish and Wildlife Service

 2:00-2:30 Mercury in Wildlife
           Dr. Charles Facemire
           U.S. Fish and Wildlife Service

2:30-3:00  Spatial Distribution of Mercury in the
          Everglades Canal System
          Dr. Jerry Stober
          U.S. Environmental Protection Agency,
          Region 4

3:00-3:30  Atmospheric Deposition Studies in Florida
          Dr. Thomas Atkeson
          Florida Department of Environmental

3:30-3:45  BREAK

3:45-4:15  Watershed Effects on Background Mercury
          Levels in Rivers
          Dr. James Hurley
          Wisconsin Department of Natural Resources

4:15-5:00  Discussion/Question-and-Answer Session

5:30-6:30  SOCIAL HOUR
Wednesday, September 28

8:00-8:25  Mercury Toxicity: An Overview
          Dr. Thomas Clarkson
          University of Rochester

8:25-8:50  An Overview of Animal Studies
          Dr. Deborah Rice
          Environment Canada

8:50-9:15  An Overview of Human Studies
          Dr. Roberta White
          Boston University

9:15-9:45  Discussion/Question-and-Answer Session

                                  Final  Agenda
 9:45-10:00 BREAK

 10:00-10:25Exposure Assessment for Methyl Mercury
           Dr. Alan Stern
           Newjersy Department of Environmental

 10:25-10:50FDA Perspective
           Dr. Michael Bolger
           US. Food and Drug Administration

 10:50-11:15EPA Perspective
           Dr. John Cicmanec
           U.S. Environmental Protection Agency

 11:15-12:OODiscussion/Question-and-Answer Session

 12:00-1:30 LUNCH


 1:30-2:00   A Review of Fish Consumption Advisories
           and Their Impact
           Dr. Robert Reinert
           University of Georgia

 2:00-2:45   Different People, Different Approaches: Risk
           Management and Communication in Minnesota
           Dr. Pamela Shubat
           Minnesota Department of Public Health

 2:45-3:15   Development of Risk-based Fish Consumption
           Guidelines in Georgia
           Dr. Randall Manning
           Georgia Department of Environmental

3:15-3:45   Managing and Communicating Mercury Risks
           in Arkansas
           Dr. Kent Thornton
           FTN Associates

3:45-4:15   Discussion/Question-and-Answer Session

4:15-5:30   Displays and Demonstrations in Nearby
           Resource Room
           •  Demonstration of National Fish Tissue
             Data Repository
           •  Demonstration of National Fish Advisory
Thursday,  September  29
8:30-9:00   National Mercury Study
           Dr. Jerry Stober, US EPA Region 4
           Dr. Steve Paulson, US EPA Newport


9:00-9:45   Mercury Deposition and the Activities of the
           Clean Air Act of 1990
           Ms. Martha Keating
           U.S. Environmental Protection Agency

9:45-10:15  Great Lakes "Virtual Elimination" Initiative
           Mr. Frank Anscombe
           U.S. EPA, Great Lakes National Program Office


10:30-11 :OOMinnesota Mercury Reduction Activities
           Mr. Pat Carey
           Minnesota Pollution Control Agency

11:00-11:30Discussion/Question-and-Answer Session

11:30-11:45Conference Wrap up and Closing
           Mr. Rick Hoffmann
           U.S. Environmental Protection Agency
    Resource Room Activities

 There will be a resource room located nearby to the
 main conference room where information will be
 available. The resource room will provide an opportu-
 nity for people to meet in small groups throughout the
 conference. There will also be computer demonstra-
                                          printed on recycled paper

                                                        List of Attendees
                                           A National Forum on Mercury in Fish
                                                    September 27-29, 1994
 Assaf Abdelghani
 Tulane University
 School of Public Health
 1501 Canal Street
 New Orleans, LA  70112
  Michael  Adams
  U.S.  Food & Drug
  HFS-247,  200 C Street, S.W.
  Washington, DC  20204
                              Jeany Anderson-Labar
                              Louisiana Oept of Env Quality
                              P.O. Box 82215
                              Baton Rouge, LA  70884
 Frank Anscombe
 77 U. Jackson Blvd.
 Chicago, IL  60604
  Tom Armitage
  USEPA  (4305)
  401 H  St., SW
  Washington, DC
Mike Armstrong
Arkansas Game & Fish Commission
#2 Natural Resources Drive
Little Rock, AR  72205
 Tom Atkeson
 Florida Department of
 Environmental Protection
 2600 Blair Stone Road
 Tallahassee, FL  32399
  Tom Augspurger
  U.S. Fish & Wildlife Service
  P.O. Box 33726
  Raleigh, NC  27636
                              Alan Auuarter
                              College Station Rd.
                              Athens, GA  30605
 Linda Bacon
 Maine OEP
 Station 17
 Augusta,  ME  04333
 Bev Baker
 USEPA Headquarters
 401 M St., S.U. (4204F)
 Washington, DC  20460
                              Alan Ballard
                              Gulf of Mexico Program
                              Bldg. 1103
                              Stennis Space Cr, MS  39529
 Lina Balluz
 Louisiana Department of Health
 234 Loyola Avenue
 Suite 620
 New Orleans,  LA  70112
 Angela Bandemehr
 77 W. Jackson Boulevard
 Chicago, IL  60604
                              Phil  Bass
                              Field Services Division
                              Mississippi Dept of Env Quality
                              P.O.  Box 10385
                              Jackson, MS  39289
 Terry Bassett
 AKZO Nobel  Chemical
 P.O.  Box  100
 Axis,  AL  36505
 Thomas Pride
 Woodward-Clyde Consul.tants
 9950 Princess  Palm Ave.
 Ste. 232
 Tampa, FL  33619
                             Michael Beck
                             LA DEQ
                             P.O. Box 82178
                             Baton Rouge, LA  70884
 Robert Benson, Ph.D.
 U.S. EPA, Region 8
 Water Management Division
 999 18th Street, Suite 500
 Denver, CO  80202
 Gary Bigham
 PTI  Environmental Services
 1601  Trapelo Road
 Waltham, MA  02154
                             Jeffrey D. Bigler
                             USEPA, 4305
                             401 M St., S.W.
                             Washington, DC  20460
Chelie Billingsley
Tetra Tech, Inc.
10306 Eaton PI., Ste.  340
Fairfax, VA  22030
Judith Black
U.S. EPA, Region 6
1445 Ross Avenue
Dallas, TX  75202
                             Nicolas Bloom
                             Frontier Geosciences,  Inc.
                             414 Pontius Avenue, N
                             Seattle,  WA  98109
Jim Blumenstook
New Jersey Department  of Health
Division of Epidemiology
3635 Quacker Bridge Road
Trenton, HJ  08625
Dr. Michael Bolger
Contaminants Branch
U.S. Food & Drug Administration
200 C Street, SW
Washington, DC  20204
                            Lorna Bozeman
                            ATSDR, US Public Health Service
                            Executive Park, Building 33
                            1600 Clifton Road, E-56
                            Atlanta, GA  30333

                                                       List of Attendees
Earl Bozeman
USEPA-Region 4 (4WD-UPB)
345 Courtland St..  HE
Atlanta, GA  30365
Bruce T. Brackin
MS Department of Health
P.O. Box 1700
Jackson, HS  39215
Duight Bradshau
Louisiana Oept of Env Quality
Office of Water Resources
P.O. Box 82215
Baton Rouge, LA  70884
 Hirk Briggs
 Minnesota Department of
 Natural  Resources
 5463 U.  Broadway
 Forest Lake,  HH  55025
 Trey Brown
 U.S. EPA, Region 4
 Federal Facility CRC
 1 Tinet Drive
 Pendleton, SC  29670
 Jim Brown
 01 in Corporation
 P.O. Box 248
 Charleston,  TN  37310
 Too Burbacher
 University of Washington
 Department of Env.  Health
 Seattle, WA  98106
 Clarence Callahan
 75 Hawthorne Street
 San Francisco, CA  94105
 Michael Callam
 1200 N St., Ste. 400
 Lincoln, NE  68509
 Roxic Cantu
 Texas Parks and Wildlife Dept
 6200 Hatchery Road
 Fort Worth, TX  76114
 Pat Carey
 Hazardous Waste Division
 Minnesota Pollution Control
 520 Lafayette Road
 St. Paul, HH  55155
 Gale Carlson
 Missouri Department of Health
 Bureau of Env Epidemiology
 210 El Mercado Plaza
 P.O. Box 57
 Jefferson City, HO  65102
 John Cicmanec
 26 U Martin Luther King
 Cincinnati. OH  45268
 Tom Clarkson
 University Medical Center
 University of Rochester
 P.O. Box EHSC
 Rochester, NY  14642
 Joe Clymire
 Tulane University
 Department of Chemistry
 Box 26
 New Orleans, LA  70118
 Paul Conzelmann
 U.S. Fish and Wildlife Service
 825 Kaliste SoIcom Road
 Lafayette, LA  70508
 Barbara Cooper
 234 Loyola Avenue
 New Orleans, LA  70119
 Emelise Cormier
 Louisiana DEQ
 P.O. Box 82215
 Baton Rouge, LA  70884
 Kirk Cormier
 Louisiana Department of
 Environmental Quality
 804 H 31st Street
 Monroe, LA  71201
 Greg Cramer
 200 C St., S.W.
 Washington, DC  20460
 Dr. Morris Cranmer
 Cranmer & Associates,  Inc.
 P.O. Box 22093
 Little Rock, AR  72221
 Philip Crocker
 1445 Ross Avenue
 Dallas, TX  75202
 Michael Crouch, PhD.
 Terra Consulting Corp
 P.O. Box 14207
 Baton Rouge, LA  70898
 Art Crowe
 Texas Natural Resource
 Conservation Commission
 2916 Teague Drive
 Tyler, TX  75701
 Linda Cunnings, PhD.
 Terra Consulting Corp
 P.O. Box 14207
 Baton Rouge, LA  70898
 William Danchuk
 Environmental Affairs
 Consolidated Natural Gas  Co
 625 Liberty Avenue, CNG Tower
 Pittsburgh, PA  15222
 Charles Demas
 USGS, Louisiana District
 3535 S. Sherwood Forest Blvd
 Baton Rouge, LA  70816

                                                      List of Attendees
Dennis Demcheck
3535 S. Sherwood Forest
Baton Rouge, LA  70816
                         Laura Dodge-Murphy
                         PTI Environmental  Services
                         1601 Trapelo Road
                         Waltham, MA  02154
                                            Laurel Driver
                                            USEPA MD-13
                                            RTP, NC  27711
Byron Ellington
TX Natural Resource
 Conservation Connission
P.O. Box 13087
Austin, TX  78711
                         Mary C. Evans
                         AR Department of He.ilth
                         300 Broopark
                         Little Rock, AR  72205
                                            Stan Evans
                                            Arkansas Department of Health
                                            4815 Harkham - Slot #32
                                            Little Rock, AR  72205
 Chuck Facemire
 U.S. Fish and Wildlife Service
 1875 Century Boulevard
 Atlanta, GA  30345
                          Laura Fadil
                          LA Office of Public Health
                          234 Loyola Avenue
                          Suite 620
                          New Orleans, LA  70112
                                             Sharon  Fancy Parrish
                                             U.S. EPA, Region 6
                                             1445 Ross Avenue
                                             Dallas, TX   75044
 Joe Ferreri
 57 Avila St.
 San Francisco, CA
Larry Fink
South Florida Water District
3301 Gun Club Rd.
West Palm Beach,  Fl.  33416
William Fitzgerald
Department of Marine Sciences
University of Connecticut
Groton, CT  06304
 Henry Folmar
 121 Fairmont Plaza
 Pearl, MS  39208
                          Marilyn Fonseea
                          USEPA Headquarters
                          401 M St., S.W. (4305)
                          Washington, DC  20460
                                             Bradley Frazier
                                             River Studies Center
                                             Univ of Wisconsin  - La Crosse
                                             La Crosse, WI  54601
 Jane Fugler
 Office of Water Resources
 P.O. Box 82215
 Baton Rouge, LA  70884-2215
                          Ed Gardetto
                          USEPA Headquarters
                          401 M St., S.W.  (4305)
                          Washington, DC  20460
                                             Michael Gibertini
                                             Midwest Research  Institute
                                             425 Volker Blvd.
                                             Kansas City, MO   64110
 John Giese
 Environmental Preservation Div
 Arkansas Department of
 Pollution Control and Ecology
 8001 National Drive
 Little Rock, AR  72219
 Dale Givens
 Louisiana Department of
 Environmental Quality
 P.O. Box 82215
 Baton Rouge, LA  70884
                          Janice Gi Hi land
                          Alabama Department of
                          Public Health
                          434 Monroe Street
                          Montgomery, AL  36130
                          Jennifer Goodwin
                          Louisiana Department  of  Health
                          234 Loyola Avenue
                          Suite 620
                          New Orleans,  LA  70118
                                             Cindy Gilmour
                                             Philadelphia Academy of Natural
                                             Benedict Research Lab
                                             7311 Benedict Avenue
                                             Benedict, MD  20612
                                             Ron Gouguet
                                             NOAA HAZMAT
                                             C/o U.S. EPA
                                             1445 Ross Avenue
                                             Dallas, TX  75202
 Jessica Graham
 MA Department of Public Health
 150 Tremont Street
 7th floor
 Boston, MA  02111
                          Gary Gulezian
                          Air Toxics and Radiation Branch
                          U.S. EPA
                          77 West Jackson Boulevard
                          Chicago, IL  60604
                                             Arthur Hagar
                                             LA Oept. of Health
                                             New Orleans, LA

                                                      List of Attendees
 Douglas Hahn
 2822 O'Heat Lane
 Baton Rouge.  LA  70816
 Hark Hale
 4401 Reedy Crk. Rd.
 Raleigh, NC  27607
 James Hanion
 U.S. EPA, Headquarters
 401 M Street,  SW
 Washington, DC  20460
 John Harju
 lox 9018
 Grand Forks. ND   85202
 Ruth Harper
 HcNeese State University
 Department of Biology and Env.
 Lake Charles, LA  70609
 Dan Harrington
 Tulane University
 1430 Tulane Ave. SL29
 New Orleans, LA  70112
 William R. Hartley
 Tulane University
 1430 Tulane Ave. SL29
 New Orleans, LA  70112
 Beth Hassett-Sipple
 RTP, NC  27711
 Mary Heagler
 HcNeese State University
 Dept of Biol and Env Science
 P.O. Box 92000
 Lake Charles, LA  70609
 Hatthea Heinrich
 Office of Water Resources
 P.O. Box 82215
 iaton Rouge, LA  70884-2215
 Thomas Herrington
 U.S. Food & Drug Administration
 Gulf of Mexico Program
 Building 1103
 Room 202
 Stennis Space Cr, MS  39529
 John L. Hesse
 Michigan Department of Public Health
 P.O. Box 30195
 Lansing, HI  48822
 Delbcrt Hicks
 College Station Rd.
 Athens, GA  30605
 Albert Hindrichs
 Louisiana Dept of Env Quality
 P.O. Box 82215
 Baton Rouge,  LA  70884
 Rick Hoffmann
 U.S. EPA, 4305
 401 M Street S.W.
 Washington,  DC  20460
 David Hohreiter
 6723 Tcwpath Road
 Sox 66
 Syracuse, NY  13214
 Jeff Holland
 Reedy Creek  Imp District
 2191 Bear Island Road
 Box 10170
 Lake Buena Vista,  FL  32830
 Joe Hollouay
 1110 Vermont Avenue
 Suite 1110
 Washington,  DC  20005
 Scott Hopkins
 Htw Mexico Environment Dept
 Surface Water Bureau
 1190 St. Francis Drive
 Santa Fe, KH  87502
 Steve Houghton
 Oklahoma DEO
 1000 NE 10th
 Oklahoma City, OK  73124
 James P. Hurley
 Wisconsin ONR
 VW Water Chemistry Lab
 660 N. Park Street
 Madison, WI  53706
Diane Hyatt
Natural Res Damage Assessment
Texas General  Land Office
1700 North Congress Avenue
Austin, TX  78701
Russell Isaac
Massachusetts DEP
1 Winter Street
Boston, MA  02108
John Jansen
Southern Company Services
P.O. Box 2625
Birmingham, AL  35202
Dr. Betty K Jensen
Pubic Service Electric and
 Gat Ccopany
80 Park Plaza 
                                                      List of Attendees
Peter Jones
New York State Department of
Environmental  Conservation
50 Wolf Road
Room 315
Albany, NY  12233
Nicole Jurczyk
Env. Science & Engineering
P.O. Box 1703
Gainesville, FL  32602-1703
904/332-3318 ext.2278
R. Deedee Kathman
Aquatic Resources Center
P.O. Box 680818
Franklin, TN  37064
Kenneth W. Kauffman
Oregon Health Division
State Office Building
800 NE Oregon St.
Portland, OR
Martha Keating
Research Triangle Park
Res Triangle, NC  27711
John Kern
NOAA/Damage Assessment
9721 Executive Center Drive
St. Petersburg, FL  33702
Patti King
MN Pollution Control Agency
520 Lafayette Road
St. Paul, MH  55155
Barbara Klieforth
Tulane University
1430 Tulane Ave. SL29
New Orleans, LA  70112
Doug Knauer
1350 Femrite Dr.
Monona, Wisconsin  53716
Barry Kohl, Ph.D.
Department of Geology
Tulane University
New Orleans, LA  70118
Fred Kopfler
Gulf of Mexico Program
Building 1103
Stermis Space Ct, MS  39529
Paul C. Koska
US EPA, Region 6
1445 Ross Ave.
Dallas, TX  75202
 Napolean Kotey
 USEPA-Region 4
 345 Courtland St.,  NE 13th  Fir.
 Atlanta, GA  30365
 Arnold Kuzmack
 401 M Street, SW
 Washington, DC  20460
 A. J. Labuz
 Allied Signal, Inc.
 1700 Milton Avenue
 Solvay, NY  13209
 Kenneth Landrum
 P.O. Box 751
 Gramercy, LA  70052
 Mike Ledet
 Louisiana Dept of Env quality
 Office of Water Resources
 P.O. Box 82215
 Baton Rouge, LA  70884
 Felix Locicero
 Technical Evaluation Section
 U.S. EPA, Region 2
 26 Federal Plaza
 New York, NY  10278
 Dennis Logan
 Coastal Environmental  Services
 1099 Winterson Road,  Suite 130
 Linthicum, MD  21090
 Brad Lyon
 University of Tennessee
 105 Mitchell Road
 Oak Ridge, TN  37831 '•
 Charlie MacPherson
 Tetra Tech, Inc.
 10306 Eaton PI., Ste. 340
 Fairfax, VA  22030
 Randall Manning
 Georgia Department of Natural
 Floyd Tower East,  Suite 1152
 205 Butler Street  SE
 Atlanta, GA  30334
 Tom HcChesney
 Arkansas Department of  Health
 4815 W. Markham -  Slot  #32
 Little Rock, AR  72205
 Moira McNamara Schoen
 OPA/OPPE (2124)
 USEPA Headquarters
 401 M St.,  S.W.
 Washington, DC  20460
 Terry D. Martin
 Winston-Salem Journal
 402 Desse Rd.
 Monroe, NC  28110
 Malcolm Meaburn
 Office of Special  Projects
 Natl Marine Fisheries  Service
 P.O. Box 12607
 Charleston, SC  2942?
 Eugene Meier
 Gulf of Mexico Program
 Building 1103, Room 202
 Stennis Space Cr,  MS  39529

                                                      List of Attendees
  Phyllis Meyer
  960 College Station Rd.
  Athens,  GA  30605
  Larry Holcney
  Ooherty,  Ruable & Butler
  150  Fifth Street Tower
  Suite 3500
  Minneapolis, HH  55402
  Steve Mierzykowski
  U.S. Fish & Wildlife Service
  1033 South Main  Street
  Old Town, HE  04460
  James K.  Hoore
  Asbury Park Press
  703 Hill  Creek Rd.
  Manahawkin, NJ  08050
  Bruce Mintz,  Chief
  Environmental  Fate Section
  Office of  Water
  U.S.  EPA,  Headquarters
  401 H Street,  SW
  Washington, DC 20460
  Kim Mortensen, PhD.
  Bur of Epidemiology/Toxicology
  Ohio Department of Health
  246 N. High Street
  Columbus, OH  43266
 Sarry Hower
 Maine Dept of Env Protection
 SHS 17
 Augusta, HE  04333
  Ron Munson
  Tetra  Tech, Inc.
  Pittsburg, PA
  Ismael Nava
  Contaminant Assessment Program
  Texas Parks & Wildlife Dept
  4200 Smith School Road
  Austin, TX  78744
 Steven Hewhouse
 Indiana Dept of Environ Hgmt
 100 H. Senate Avenue
 P.O. Box 6015
 Indianapolis, IH  46206
 AI Nissen
 Louisiana Dept of Env Quality
 Office of Water Resources
 P.O. Box 82215
 Baton Rouge, LA  70884
 Toni B. Odom
 01 in Corporation
 P.O. Box 28-Olin Rd.
 Mclntosh, AL  36553
 David Oge'
 Louisiana Dept of Env Quality
 Office of W»ter Resources
 P.O. Eox 82215
 iaton Rouge, LA  70884
 Cheryl Overstreet
 U.S. EPA, Region 6
 1445 Ross Avenue
 Dallas, TX  75075
 Heera Parab
 Public Health Program Offices
 DHH/OPH,  Engineering  Department
 325 Loyola Avenue
 Room 403
 New Orleans,  LA   70112
 Rindi Parks Thomas
 U.S. Tuna Foundation
 1101 17th Street,  NW
 Uiihington, DC  20036
 Tonie Patterson
 Governor Tucker's  Office
 State Capitol,  Room 238
 Little Rock,  AR 72201
 Gary Pederson
 3850 Holcomb Br.  Rd.
 Norcross,  GA  30092
 Steve Perry
 6163 Brandy Run Rd.
 Hobile,  AL  36608
 Hark Peterson
 Oak Ridge National Laboratory
 P.O. Box 2008
 ORNL,  Building  1505
 Oak Ridge, TN   37831
 Marjorie Pitts
 U.S.  EPA,  Headquarters
 401 M Street, SW
 Washington, DC  20460
Jerry Pollock
601 H. 7th St  (HS 241)
P.O.  Box 942732
Sacramento, CA 94234
Don ForceUa
Electric Power Research
3412 Hillview Avenue
Palo Alto, CA  94303
Donald Porteous
60 Westview Street
Lexington, MA  02173
Bob Presley
Texas ASM University
Oceanography - HS 3146
College Station, TX  77843
Drew J. Puffer
USEPA Gulf of Mexico Program
Bldg. 1103, Room 202
Stennis SpaceCtr, MS  39529
Lori Rabuck
River Studies Center
Univ of Wisconsin—La Crosse
La Crosse, WI  54601

                                                    List of Attendees
Lisa H.  Ramirez
Applied Marine Res.  Lab
1034 U 45th St.
Norfolk, VA  23529
Dianne Ray
Louisiana Department of
Environmental Quality
8618 G.S.R.I. Avenue
Baton Rouge, LA  70310
Rob Reash
American Electric Power
1 Riverside Plaza
Columbus, OH  43215
Bob Reinert
School of Forest Resources
University of Georgia
Athens, GA  30602
Vincent L. Reynolds
Radian Corp.
Austin, TX  78759
Ken Rice
Texas Parks and Wildlife Oept
6300 Ocean Drive
Corpus Christi, TX  78412
Glenn Rice
M.S. 190
26 U.H.L. King
Cincinnati, OH  45268
Deborah Rice
Toxicology Research Division
Banting Research Center
Tuneys Pasture
Ohowa, Ontario
Canada,   K1AOL
Shano Rizvi
Office  of Water Resources
P.O. Box 82215
Baton Rouge,  LA  70884-2215
 Barbara Romanowsky
 LA Dept. of Env. Quality
 P.O. Box 82215
 Baton Rouge,  LA  70884
 Lonnie Ross
 U.S.  EPA,  Region 6
 1445  Ross  Avenue, Suite 1200
 Dallas, TX  75126
Alan Rovira
HcNeese State University
3145 O'Neil Road
Baton Rouge,  LA   70809
 David Sager,  Chief
 Texas Parks and Wildlife Dept
 4200 Smith  School Road
 Austin,  TX  78744
 Jay Sauber
 North Carolina Environmental
 4401 Reedy Creek Road
 Raleigh, NC  27607
 Bobby Savoie
 LA Department of  Health
 P.O.  Box 629
 Baton Rouge, LA  70821
 Julie Sbeghen
 Hydro Quebec
 75 Rene Levesgue Quest
 Montreal,  Quebec  H2Z14A
 Rita Schoeny
 26 W. Martin Luther King  Dr.
 Cincinnati, OH  45268
 William Schramm
 Louisiana Department of
 Environmental Quality
 P.O. Box 82215
 Batch Rouge, LA  70884
 Bruce Schuld
 Water Quality Compliance Office
 Idaho Division of Env Quality
 1420 N. Hilton
 Boise, ID  83703
 Doug LaBar
 Water Quality Division
 C-K Associates,  Inc.
 17170 Purkins Roael
 Baton Rouge, LA   70810
 Dave Serdar
 Washington State Department
 of Ecology
 300 Desmond Drive
 Box 4-7710
 Olympia, WA  98504
 Walter Shepard
 Allied Signal
 P.O. Box 6
 1700 Milton Avenue
 Solvay, NY  13209
  Pam Shields
  U.S.  EPA,  Rgion 1
  Water Management division
  JFK Federal Building
  Boston,  MA  02203
 Pam Shubat
 MM Department of Health
 P.O. Box 59040
 Minneapolis, MN  55459
  Dennis  Smith
  Zeneca  Inc.
  P.O.  Box 32
  Bucks,  AL  36512
  Stephanie Smith
  234 Loyola Avenue
  New Orleans, LA  70119
 Elaine Sorbet
 Louisiana Department of
 Environmental Quality
 8618  C.S.R.I. Avenue
 Baton Rouge, LA  70810

                                                       List of Attendees
  George Spencer
  /ir..DaUy and Air Quality Week
  4418 HacArthur Boulevard, NW
  Washington,  DC  20007
  Jerry Stober
  U.S.  EPA, Region 4
  Environmental Services Division
  College Station Road
  Athens, GA  30613
  Alan Stern
  Div. of Science and Research
  Hew Jersey DEP
  401 E. State Street
  Trenton,  NJ  08625
  Claus Suverkropp
  Larry Walker Associates
  509 Fourth  Street
  Davis,  CA   95616
  Barbara Stifel
  Oregon Dept of Env Quality
  811 SW sixth Street
  Portland, OR  97204
  Susan Svirsky
  U.S. EPA, Region 1
  JFK Federal Building
  Boston, MA  02203
  Jeff Swartout
  USEPA (HS190)
  26 U. Martin Luther King Dr.
  Cincinnati, OH  45268
 Dr. Hark Tisa
 Massachusetts Division of
 Fisheries and Wildlife
 29 Pheasant Hollow Run
 Princeton, HA  01541
  Rani Thiyagarajah
  921 Hesper Ave.
  Metairie, LA  70005
 Kimberly Tisa
 U.S. EPA, Region 1
 JFK Federal Building
 Boston, HA  02203
  Kent Thornton
  FTN Associated, Ltd
  3 Innwood Circle
  Suite 220
  Little Rock,  AR  72211
 Don Tolbert
 LeMoyne Citizens Advisory Panel
 13040 N. Forest Dr.
 Axis, AL  36505
 Don Turman
 5^5°*.*? Caroe & Flsh  Conraission
 2320 Chidcster  Road
 Camden,  AR  71701
 Steve Twiduell
 Texas Natural Resource
 Conservation Commission
 P.O.  Box  13087
 Austin, TX  78711
 Steve Ugoretz
 1350 Femrite Dr.
 Honona, WI  53716
 Yvonne H. Vallctte
 USEPA Region 6
 1445 Ross Ave.
 Dallas, TX  75202
 John Villanacci
 TX Department of Health
 1100 W. 49th St.
 Austin, TX  78756
 Dallas  Wait
 Gradient  Corporation
 Cambridge, MA   02138
Jeff Waters
T-Utyne Environmental Law Clinic
7039 Freret Street
Hew Orleans, LA  20118
 Susan Wenberg
 1777  H. Kent St.
 8th Floor
 Arlington, VA  22209
James Wiener, PhD.
Hationtl Biological Survey
Hatl Fisheries Research Center
2630 Fanta Reed Road
La Crosse, WI  54602
Carl Watras
10810 Cty.  N
Boulder Jet.,  WI   54512
 Linda West
 U.S. Public Health Service
 1600 Clifton Road, NE
 Atlanta, GA  30333
Kirk Wiles
TX Department of Health
1100 W. 49th St.
Austin, TX  78753
Lee Weddig
National Fisheries  Institute
1525 Wilson Boulevard
Suite 500
Arlington, VA  22209
 Roberta White
 Boston University
 DVA Medical
 150 S.  Huntington Avenue
 Boston,  MA   02130
 Luanne Williams
 North Carolina Department of
 Environ Health and Natural Res
 Env Epidemiology Section
 P.O. Box 27687
 Raleigh, NC  27611

                                                    List of Attendees
Hark Wood
P.O. Box 1000
Lake Charles, LA  70602
Jarrett Woodrow
Texas Parks and Wildlife Oept
P.O. Box 8
Seabrook, TX  77586
Jay Wright
Oklahoma DEQ
1000 NE 10th
Oklahoma City, OK
Roger Yeardley
3411 Church Street
Cincinnati, OH  45244
Carl Young
U.S. EPA,  Region 6
1445 Ross  Avenue
Suite 1200
Dallas,  TX  75202
Edward Younginer
2600 Bull Street
Columbia, SC  29201
Gary Zarling
Minnesota Department of
Natural Resources
5463 W. Broadway
Forest Lake, MM  55025
David Zircmer
Bureau of Reclamation
1150 North Curtis  Road
Boise, ID  83706-1234
Jim Zarzycki
EA Engineering
2 Oakway
Berkeley Heights,
NJ  07922


     Mercury Advisory
                                         Fact Sheet
Summary Informations
Number of Water bodies
with Advisories          2
     Basis of Advisory

     Date Advisory Issued
                          FDA action level

Olin Basin

Cold Creek Swamp

natural lake

Swamp area

Prohibits consumption of largemouth bass and

Prohibits the consumption of any fish

Point source inputs
from chemical
company (manu-
factured chlorine
and caustic soda)
Point source inputs
from chemical
 Comments:  Further data is expected and will be released when received. Will update the advisories
 as necessary.
 Contacts   Brian Hughes, Alabama Department of Public Health (205) 613-5347

           Mercury Advisory
                                                Fact Sheet
    Summary Information:
     1.   Number of Water bodies
          with Advisories!
    35.   Basis of Advisory
    3.   Date Advisory Issued
                           FDA action level

                           First issued in August 1991; presently under review
   Lake Columbia

   Cut-off Creek
   Bayou Bartholomew
   Big Johnson Lake
   Snow Lake
   Grays Lake
   Moro Bay Creek
   Champagnolle Creek
   Ouach'rta River
   Felsenthal Wildlife Refuge
  I All ox-bow lakes, backwa-
  ters, overflow lakes, and
  I barrow drtches formed by
  I Saline River
  (at 2 locations)
  Dorcheat Bayou
  Fouche La Fave River
 I Johnson Hole
 I Lake Wfnona
          General Recommendation: "Pregnant women, women who plan to get pregnant, women
          who are breast-feeding, and children under the age of 7 years are considered high risk
          groups  and should not eat fish from the consumption notice areas


 No more than 2 meals/month for mixed species
 (8 ounces=1 meal); No restrictions on largemouth
 oass 16". All
                      others, no more than 2 meals/month

                      Ni°«m°Aiith*un 2 meals/month of largemouth bass
                      >16". All others, no restrictions
                      No consumption of largemouth bass >16". All
                      others, no more than Zmeals/month
                      No consumption of largemouth bass >16". All
                      others, no more than ?meals/month
                      No more than 2 meals/month of black bass >1 6"
                      All others, no restrictions
atmospheric deposi-
tion and naturally
Mike Armstrong, Arkansas Fish and Wildlife Service (501) 223-6300

     Mercury Advisory
Summary Information:
                                Fact Sheet
 1.   Number of Water bodies
     with Advisories

 2.   Basis of Advisory

 3.   Date Advisory Issued
                 3 (includes methyl mercury)


                 1989, reissued in 1994
Gila River to the Painted
Rocks Barrow Pit Lake,
Salt River below or west of
59th Avenue in Phoenix,
and Hassayampa River
from the Buckeye Canal to
the Gila River
River flowing
into a Lake

Prohibits the consumption of any fish or other
aquatic animals

Methyl mercury
inputs from nearby
sewage plant.
Possible nonpoint
source inputs from
agricultural sources.

Comments!  Data is currently under analysis.
Marc Dahl, Arizona Department of Game and Fish (602) 789-3260

         Mercury Advisory


  Summary Information:
                                             Fact Sheet
   1.    Number of Waterbodlos
         with Advisories

   E.    Basis of Advisory

   3.    Date Advisory Issued
                         On-site risk assessment for sport fish; FDA action level for
                         commercial fish

                         1st advisory issued in 1971; others issued in the mid to
                         late 1980's; most recent one in 1993
         General Recommendation: For the sites listed below, "Pregnant women, women who may
         soon become pregnant, nursing mothers, and children under 15" should either eat reduced
         portions or no fish from the affected areas.
  Clear Lake
 San Francisco Bay Delta

 Lake Nacimlento

  .ake Berryessa
  ,ake Herman

 Guadalupe River, Creek
  nd Reservoir; Calero
  leservolr; Alamaden
 Reservoir; Alamftos Creek;
  nd associated percolation
  onds along the river and



 largemouth bass > 15" - no more than 11b/month, or
 < 15" - no more than 2 Ibs /month; or
 channel catfish > 24" - no more than 11b/month, or
 < 24" - no more than 3 Ibs/month; or
 crappie > 12" - no more than 1 Ib/month, or <12" - no
 more than 3 Ibs/month; or
 all white catfish - no more than 3lbs/month; or
 all brown bullhead - no more than Gibs/month; or
 all Sacramento blackfish - no more than 6 Ibs/month;
 all hitch - no more than 10 Ibs/month

 striped bass between 18-27" - no more than 4-7 Ibs/
 month, or between 27-35" - no more than 2-4 Ibs/
 month, > 35" - no consumption.

 largemouth bass - no more than 4 meals/month

 largemouth bass > 15"- no more than 1 Ib/month, or
 largemouth bass < 15" - no more than 2 Ibs/month, or
 all smallmouth bass - no more than 11b/month, or
 all channel catfish - no more than  3 Ibs/month, or
 all white catfish - no more than 2 Ibs/month, or
 all rainbow trout - no more than 10 Ibs/month

 largemouth bass - no more than 1 Ib/month

No consumption of any fish
deposition and
occurring, mining
Anna M. Fan, Office of Environmental Health Hazard Assessment (510) 540-3063

       Mercury Advisory
                                            Fact SIHeet
Sumnnary Informations
       Number of Water bodies
       with Advisories             3
       Basis of Advisory

       Date Advisory Issued

                       1st advisory issued in 1970's; others issued in the mid to
              PW SB Pregnant women, nursing women and women who plan on being
              pregnant and children under 9 years of age.
 Navajo Reservoir
 McPhee Reservoir
  Narraguinnep Reservoir
Northern pike 30-36 in. Eat no more than 4 meals/
month, PW no mores than 1 meal/month; 36-42 in. no
more than 2 meals/month, PW Do not consume;
Smallmouth bass12-18 in. no more than 4 meals/
month, PW no more than 1 meal/month; Channel
catfish12-18 in. no more than 8 meals/month,, PW no
more than 2 meals/month.
Rainbow trout-6-12 in. Eat no more than 14 meals/
month, PW no more than 3.5 meals/month and 12-18
in. no more than 8 rneals/month, PW no more than 2
meals/month; Yellow perch-1-6 in. no more than 14
meals/month, PW no more than 3.5 meals/month and
6-12 in. no more than 8 meals/month, PW no more than
2 meals/month;Smallmouth bass 1-12 in. no more than
8 meals/month, PW no more than 2 meals/month;
Largemouth bass 12-18 in. no more than 2 meals/
month, PW Do not consume; Black crappie 6-12 in. no
more than 4 meals/month, PW no more than 1 meal/
month; Kokanee salmon 12-18 in. no more than 14
meals/month, PW no more than 3.5 meals/month.
Northern pike 12-18 in. Eat no more than 8 meals/
month, PW no more than 2 meals/month, 18-30 in. no
more than 4 meals/month, PW no more than 1 meal/
month, 30-36 in. no more than 2 meals/month, PW Do
not consume; Walleye 6-12 in. no more than 8 meals/
month, PW no more than 2 meals/month, 12-18 in. no
more than 4 meals/month, PW no more than 1 meal/
month, 18-24 in. no more than 2 meals/month, PW Do
not consume; Channel catfish 18-24 in. no more than 4
meals/month, PW no more than 1 meal/month; Yellow
perch 1-6 in. no more than 14 meals/month, PW no
more than 3.5 meals/month, 6-12 in. no more than 8
meals/month, PW no more than 2 meals/month.
Robert McConnell, CO Department of Health, (303) 692-2000

     Mercury Advisory


Summary Informations
                                              Fact Sheet
     Number of Waterbodles
     with Advisories
     Basis of Advisory

     Date Advisory Issued

                               1st advisory issued in 1992; reissued annually
Dodge Pond
Prohibits the consumption of any fish by pregnant
women, women who may become pregnant in the
near future or children under 1 5 years old. Others
should eat no more than 2 meals/month.
May be from indus-
trial sources. No
studies have been
            Brian Toal, Connecticut Department of Health, (203) 240-9022

      Mercury Advisory


Summary Informations
                           Fact Sheet
 1.   Number of Watorbodies
      with Advisories


         1st advisory issued in 1989
      Basis of Advisory

      Date Advisory Issued
General Recommendation: For the sites listed below, "women of childbearing
age and children should limit their consumption to one meal per month" from
waters where mercuiy concentrations in fish are between 0.5 ppm and 1.5 ppm.
Majority of Everglades
National Park, and Water
Conservation Areas 2a
and 3
Evenly distributed over
the rest of the state
marsh land
Rivers, creeks,
ponds, lakes
Prohibits any consumption of largemouth bass,
bowfin, and gar (where concentrations are above
1 .5 ppm). Approximately 1 million acreas affected.
For largemouth bass, bowfin, and gar (where
concentrations are between 0.5 ppm and 1.5 ppm),
consumption is limited to no more than one meal
per week (one meal = 8 ounces). Approximately 1
million acres affected.
Peat drainage,
hydrologic alter-
ation, and atmo-
Primarily from
atmospheric inputs
as well as lingering
point source inputs.
 Comments:    The Department of Health and Rehabilitative Services health risk assessment has
 determined that fish having less than 0.5 ppm of mercury represent no dietary risk; fish containing 0.5 ppm to 1.5
 ppm should be consumed only in limited amounts; and fish having greater than 1.5 ppm should not be consumed.

 Over 50 percent of the State's water-bodies are currently under mercury advisories.
 Contacts    Tom Atkeson, Florida Department of Environmental Protection (904) 921 -0884

        Mercury Advisory
  Summary Informations
 1.   Number off Waterbodl
      with Advisories

St.   Basis of Advisory

3.   Date Advisory Issued
                                       FDA action level (see comments below)

                                       1989, reissued annually
   Suwanee Basin
   Purvis Creek, Gibson
   Greek, and Turtle River
                        Swamp area
Limits consumption of mixed species to 1
meal per week. Pregnant women, nursing
mothers, females of ohildbearing age, and
children under 15 years old should not
consume mixed species more than once a
month. Prohibits the consumption of large-
mouth bass entirely.

Prohibits the consumption of any seafood.
                                                                         Naturally occurring.
                                                                         Low pH.
                                                                       Point source inputs
                                                                       from chemical
 Comments:  The state is converting to a new system that is risk-based. New data is being collected.
             Randall Manning, Georgia DNR, (404) 656-4905

     Mercury Advisory

Summary Informations
                                          Fact Sheet
      Number of Waterbodl
      with Advisories

Basis of Advisory

Date Advisory Issued
                  General Recommendation: pregnant women, women planning a pregnancy and
                  children under 7 years old should consume one-fifth of the amounts listed below.
Brownlee Reservoir


For yellow perch, smallmouth bass, and large
crappie over 10" - no more than 60 7-ounce
For catfish and crappie less than 10 "• no more
than 120 7-ounce meals/year.

Naturally occurring;
Possibly historic
mining activities

 Contact:    Russell Duke, Idaho Department of Health and Welfare, (208)334-4964

        Mercury Advisory


   Summary Information:
                                      Fact Sheet
        Number of Waterbodles
        with Advisories           2
        Basis of Advisory

        Date Advisory Issued
                      FDA action level (see comments below)

       1: Lowest levels of contaminants, fish pose little or no hearth risks
Kinkafd Lake
Cedar Lake
largemouth and spotted bass** (Group 2)
largemouth and spotted bass >18"** (Group 2)

         : High levels on contaminants; no one should eat Group 3 fish.
   EXCeedenCe °f FDA action level tri99ers further multi-disciplinary studies before
Dr. Robert Flentge, Divison of Food, Drug and Dairy (217) 785-2439

     Mercury Advisory
                                       Fact Sheet

Summary Information:
     Number of Waterbodles
     with Advisories          5
                              FDA action level

Basis of Advisory

Date Advisory Issued
West Kentucky Wildlife
Management Area

Ponds (i.e., Fire
Horseshoe, New
Pond, Box
Factory and
Gravel Pit No. 1)
Prohibits the consumption of largemouth bass


 Contacts    Michael Mills, Department for Environmental Protection, (502)564-3410

       Mercury Advisory
                                                Fact Sheet
  Summary Information:
   1.   Number of Watarbodles
       with Advisories           1

                                  1992, reissued 1994
2.   Basis of Advisory

3.   Date Advisory Issued

Ouachrta River



Restricts the consumption of bass to no more
than 2 meals/month. All other species, no
Pregnant women and children under 7 years of
age should consume no bass and limit consump-
tion of other species to 2 meals/month (8oz. =
Unknown; possibly
deposition, natural
occurrence, or
discharge from old
mercury mines.

          h nw  °"T? SamP!l,n9 fe tar9eting baSS> Crappie' and catfish- statewide sampling to identify
   extent of the problem is being conducted.
            Emelise Cormier, Louisiana Department of Environmental Quality, (504)765-051'

     Mercury Advisory
                           Fact Sheet

Summary Informations
      Number of Waterbodles
      with Advisories           Statewide for lakes, ponds, and rivers

      Basis of Advisory         Risk-based

      Date Advisory Issued     June 1994
General Recommendation: For the advisory listed below, pregnant women,
nursing mothers, women who may become pregnant and children under 8 years old
should not consume any freshwater fish species from state lakes, ponds, and rivers.

Statewide for lakes, ponds,
and rivers

All lakes, ponds,
and rivers


Consumption should be limited to 6-22 meals/
year for all freshwater fish species (number of
meals vary depending on the size of the fish).


In the past, point
sources were a
major contributor
to mercury
Now mercury
concentrations are
most likely linked
to atmospheric
  Contacts   Evangelos Dimitriadis, State Toxicologist, (207) 287-5378

        Mercury Advisory
                                                       Fact Sheet
  Summary Information:
Number of Water-bodies
with Advisories
Basis of Advisory

Date Advisory Issued
                                           18 waterbodies for specific advisories; statewide advisory
                                           for pregnant women only

                                           0.5 ppm for sensitive population;
                                           1.0 ppm for general population

                                           1986 to present
                        All freshwater
 Turner Pond
 Walden Pond
 Pepperell Pond
 Pontoosue Lake
 Powder Mill Pond
 Quabbln and Wachusetts
 Quaboag Pond
 South Pond
 Sudbury River
 Sudbury Reservoir
 Mill Pond (above G.H.
    Nfchols Dam)
 Millers Rfver and tributaries
    below the confluence
    with the Otter River
 Noquochoke Lake
Waite Pond
Cedar Swamp Pond
Concord River
Coplcut River/Cornell Pond
Factory Pond



                               Advises pregnant women not to consume certain fish
                               from freshwater bodies.  Does not apply to fish
                               stocked in freshwater bodies by the State Division of
                               Fisheries and Wildlife and does not apply to farm-
                               raised freshwater fish sold commercially.
 All species (P1,P5)*
 largemouth and smallmouth bass (P1, P3)*
 largemouth bass (P1, P2, P4)*
 largemouth bass (P1, P3)*
 All species offish (P1, P5)*
 lake trout > 24", largemouth and
 smallmouth bass (1)*
 largemouth bass (P1, P2, P4)*
 All species of fish (P1, P5)*
 All species of fish (P6)*
 largemouth bass (P1, P2)*

 brown trout and American eel (P1, P2, P4)*

 largemouth bass (P1, P2, P4)*
 All species offish (P1, P5)*
 All species offish (P1, P5)*
 largemouth bass (P1, P2, P4)*
 largemouth bass (P1, P3)*
All species of fish (P6)*
                                                            Point Source

               Elaine Kruger, Department of Health, (617) 727-7170

      Mercury Advisory
                                   Fael Sheet
Summary Informations
 1.    Number of Waterbodk
       with Advisories

 2.    Basis of Advisory

 3.    Date Advisory Issued

                 1st advisory in 1970 for selected waterbodies; statewide
                 advisory for all inland lakes in 1989
            Genera! Recommendation: For all inland lakes and reservoirs, the
            advisory recommends that "nursing mothers, pregnant women, women
            who intend to have children, and children under age 15 should not eat
            more than one meal per month" of the fish species listed below.
 All inland lakes
 and reservoirs
No one should eat more than one meal per week
of fish of the following kinds and sizes from any of
Michigan's inland lakes and reservoirs: rock
bass, perch, or crappie over 9 inches in length;
largemouth bass, smallmouth bass, walleye,
northern pike, or muskie of any size.

Some species and sizes from a few lakes have
been found to contain mercury far above levels of
concern and the Health Department recommends
that no one eat the size and species of fish from
those specific areas.
                                                                               naturally occur-
                                                                               ring, atmospheric.
 Comments:     The Great Lakes are treated separately under different advisories. For specific
 Great Lakes advisories and other specific waters, contact the Michigan Department of Public Health.

 The Michigan action level for mercury is 0.5 ppm.
 Contact!    John Hesse, Michigan Department of Health, (517) 335-8353

          Mercury Advisory
                                            Fact Sheet
    Summary Informations


                          1st issued in 1975; Updated annually (May release)
     1 •   Number of Waterbodles
          with Advisories

    2.   Basis of Advisory

    3.   Date Advisory Issued
  Minnesota lakes and
          "nr0nnal?eCOmrnend^tl0n: *?'the 5™ sites tssted-the advisory recommends that
           pregnant women, nursing mothers, women who may become pregnant in the next several
        lakes and
                                             meal per week, one meal a month, and do not eat
Mercury levels of |ess than 0.16, 0.16 to 0.65, 0.66 to
2.8 and more than 2.8 parts per million in fish
correspond to meal advice categories of unlimited
meals, one meal a week, one meal a month, and do
not eat, respectively.

The most common species affected by the advisories
are the northern pike, walleye, crappie and bluegill.

 Estimated that 25%
 of the mercury is
 natural in origin.
 The remaining 75%
 comes from
 airborne deposits
 from burning of coal
 and other fossil
fuels, burning of
 municipal solid
waste, and from
fungicides that were
used in latex paints.
Pam Shubat, Minnesota Department of Health, (612) 627-5479

    Mercury Advisory
                                          Fact Slbeet
Summary Information:
 1.  Number of Water bodies
     with Advisories         2

                              1st issued in 1993
2.  Basis of Advisory

3.  Date Advisory Issued
Merr'rtt, Oliver, and Box
Butte Reservoirs
These advisories are intended primarily for pregnant
or nursing women and infants and children under 15
years of age.
 Contact:   Michael Callam, Department of Environmental Quality, (402) 471-4249

         Mercury Advisory
                                                        Fact Sheet
   Summary Informations
                                         FDA action level

                                         1st issued in 1989; reissued annually
 1.   Number of Waterbodles
      with Advisories            1

38.   Basis off Advisory

3-   Date Advisory Issued
                                 taMo ™f,Sndation: The advisory recommends that "children
                               under 12, pregnant women, nursing mothers and women who may soon
                               become pregnant should not consume fish from" either of the water
                               bodies listed below.
  Lahontan Reservoir
  Carson River below
  Lahontan Reservoir and
  all waters in Lahontan
Adults should eat no more than one 8-ounce meal/
month; children 12-15 years of age should eat no
more than one 4-ounce meal/month;  Gamefish over
21 inches in length should not be eaten.

Adults should eat no more than one 8-ounce meal/

                                                                       Point source

                                                                       contributions from
             Leroy McLelland, Division of Wildlife, Fishery Bureau, (702) 688-1500

     Mercury Advisory
   ew  Hampshire
                                          Pact Sheet
 Summary Information:
1.  Number of Waierbodi
    with Advisories

2.  Basis of Advisory

3.  Date Advisory Issued

                              FDA action level and Risk-based

                              June 10,1994
Horseshoe Pond
The public is advised to not eat largemouth bass from
Horseshoe pond. This warning especially applies to
pregnant women, nursing mothers, women who may
become pregnant and young children.
Contact:   John Dreisig, NH Division of Public Health Services, (603) 271 -4664

     Mercury Advisory
 New Jersey
                               Fact Sheet
 Summary Information:
  1.   Number of Waterbodles
      with Advisories

 2.   Basis of Advisory

 3.   Date Advisory Issued


                 February 4,1994
Freshwater bodies

Pinelands area

Freshwater bodies (Non-

Lakes, Streams,
Rivers, and


Lakes, Streams,
Rivers, and

People should limit their consumption of largemouth
bass and chain pickerel from several of New Jersey's
tested freshwater bodies to no more than one meal/
week. Pregnant women, women planning pregnancy
within a year, nursing mothers and children under five
years old are urged to limit consumption of these
species to one meal/month.
People are urged to limit their consumption of
largemouth bass and chain pickerel to one meal/
month. Pregnant women, women planning preg-
nancy within a year, nursing mothers and children
under five years old are urged to not consume the fish
at any time.
For the non-tested freshwater bodies, people are
urged to limit their consumption of largemouth bass
and chain pickerel to no more than one meal/week.
Pregnant women, women planning pregnancy within
a year, nursing mothers and children under five years
old are urged to limit consumption of these species to
one meal/month.




John Makai, NJ Department of Environmental Protection and Energy , (609) 748-2020

       Mercury Advisory
                                                              Fact Sheet
 Summary  Informations
1.   Number of Water bod i
      with Advisories

2.   Basis of Advisory

3.   Date Advisory Issued

                                            FDA action level

                                            1st issued in 1970; Last revision was in 1993
 Throughout the
                     and rivers
Group 1: Pregnant women should eat no more than one
meal/month of fish of certain sizes. No other restrictions

Group 2: Fish of certain sizes in this group should not
be eaten by pregnant or breast-feeding women, women
who plan to have children, or anyone under 18 years of
age.  Everyone else should eat no more than 26 meals/
year. Eat no more than 13 of these 26 meals in one
month. The remaining meals should be evenly spaced
over the remainder of the year.

Group 3: Fish of certain sizes in this group should not
be eaten by pregnant or breast-feeding women, women
who plan to have children, or anyone under 18 years of
age.  Everyone else should eat no more than 13 meals/
year. Eat no more than 7 of these 13 meals in any one
month. The remaining meals should be evenly spaced
over the remainder of the year.
                                     Group 4: Fish of this size should not be eaten by
Species affected: largemouth bass, channel catfish, bass, walleye, white bass, black bass, bluegill, crappie, carp, carpsucker,
bullhead, northern pike, trout, white crappie, black crappie, brown trout, Kokanee salmon, white sucker, lake trout, yellow
perch, black bullhead, river carpsucker

Group 1: Based on different sizes for different species; Skin-on fillet samples average 0.5 ppm mercury or less.
Group 2: Based on different sizes for different species; Skin-on fillet samples average 0.5-0.75 ppm mercury.
Group 3: Based on different sizes for different species; Skin-on fillet samples average 0.75-1.0 ppm mercury.
Group 4: Based on different sizes for different species; Skin-on fillet samples average >1.0 ppm mercury.

Contacts    Steven Pierce, NM Surface Water Quality Bureau, (505)827-2800

      Mercury Advisory
New Yorlc
                                     Fact Sheet
 Summary Informations
  1.   Number of Water bodies
       with Advisories

  E.   Basis of Advisory

  3.   Date Advisory Issued

                     FDA action level

                     1st issued in 1970; advisories are updated annually
               General Recommendation: For all waterbodies listed below, the
               advisory recommends that "women of childbearing age, infants and
               children under 15 should not eat any fish species".
Big Moose Lake
Carry Falls Reservoir
Ferris Lake
Francis Lake
Hatfmoon Lake
Indian Lake
Lake Champlain
(Whole Lake)
Long Pond
Meacham Lake
Moshier Reservoir
Onondaga Lake
Round Pond
Stillwater Reservoir
Sunday Lake
yellow perch - no more than one meal/month
(1 meal = Bounces)
walleye - no more than one meal/ month
yellow perch >12" - do not consume; <12" no more
than one meal/month
yellow perch - no more than one meal/month
yellow perch - no more than one meal/month
All species - no more than one meal/month
lake trout >25" , walleye >19" - no more than one
splake >12" - do not consume
yellow perch >12" - do not consume; <12" - no more
than one meal/month
yellow perch - no more than one meal/month
All species - do not consume
yellow perch >12" - no more than one meal/month
splake - no more than one meal/month
yellow perch - no more than one meal/month

deposition and
point source

Larry Skinner, New York State Department of Environmental Conservation, (518) 457-1769

      Mercury Advisory
 North  Carolina
                                     Pact Sheet
 Summary Informations
  1.   Number of Water-bodies
       with Advisories           5 active, 1 inactive
       Basis of Advisory

       Date Advisory Issued
                     Risk-based action level of 1 pprn

                     See below
            "General Recommendation: For all waterbodies listed below, the advisory
            recommends that women of childbearing age, and children should eat none of the
            specified species from areas listed.

            "Date advisory issued.
Abbotts Creek,
Leonards Creek
Pages Lake (7/93)**
Pit Links Lake (7/93)**
Watson Lake (7/93)**
Big Creek/Waccamaw
River (7/93)**
. Lake
Consumption of fish should be limited to no more than
8 ounces per person per week.*
Consumption of largemouth bass should be limited to
no more than two meals per person per month.*
Consumption of largemouth bass should be limited to
no more than two meals per person per month.*
Consumption of largemouth bass should be limited to
no more than two meals per person per month.*
Consumption of bass and blackfish should be limited
to no more than two meals per person per month.*



Luanne Williams, NC Department of Environment, Health, and Natural Resources (919) 733-3410

      Mercury Advisory
                                    Fact Sheet

 Summary Information:
  1.   Number of Waterbodles
       with Advisories             17

  2.   Basis of Advisory          Risk-based

  3.   Date Advisory Issued     1992
General Recommendation:
Women who plan to become pregnant, are pregnant or breast-feeding, or children who are
under that age of 15, are health sensitive and should consume no more than 2 meals per
month of any species if they are under a certain length. No restrictions for the general popula-

Women who plan to become pregnant, are pregnant or breast-feeding, or children who are
under that age of 15, are health sensitive and should not consume any of these species if they
exceed a certain length. The general population is then restricted for future intake of fish to
timeframes ranging from 10 to 22 days after consumption of the fish.
Throughout the State
dams, reservoirs,
lakes, and portions
of the Missouri and
Red River.
Species affected: brown bullhead, northern pike,
walleye, white bass, white sucker, yellow perch,
goldeye, carp sucker, sauger channel catfish, Chinook
salmon, crappie, paddlefisn, smallmouth bass,
bigmouth buffalo, rainbow trout, largemouth bass
Naturally occurring:
probably some
atmospheric inputs
Contacts    Mike Sauer, ND State Department of Health & Consolidated Laboratories, (701) 221 -5210

     Mercury Advisory
              Pad: Sheet
 Summary Information:


      Number of Waterbodles
      with Advisories          1
      Basis of Advisory

      Date Advisory Issued
FDA action level

1st issued in 1992
McGee Creek Reservoir
Prohibits consumption of largemouth bass
geologic sources
Contact:   Judith Duncan, Oklahoma Department of Environmental Quality, (405) 271 -5240

      Mercury Advisory
                                   Fact Sheet
 Summary  Information:
  1.   Number off Waterbodles
       with Advisories

  2.   Basis of Advisory

  3.   Dale Advisory Issued

                  Cottage Grove 1987,1993; Antelope Reservoir 1988,1989;|
                  Jordan Creek 1988,1989; Owyhee Reservoir 1988,1994.
 Cottage Grove
 Antelope Reservoir and
 Jordan Creek
 Owyhee Reservoir
              Consumption of fish should be limited to no more than
              8 ounces per week. General prohibition against any
              consumption by children younger than 6 years or by
              pregnant or nursing women.

              Children between 6 and 16 years of age should not
              eat more than 21/2 ounces of fish per month and
              the general population should not eat more than 5.3
              ounces of fish per month

              Limit consumption of fish to no more than 8 ounces
              six times a year. Prohibition of consumption by
              children under 6, nursing women, pregnant women or
              women planning to  become pregnant.
                               Natural sources
                               and possibly past
                               mining activities
Contacts    Ken Kauffman, Oregon Department of Human Resources, (503) 731 -4015

     Mercury Advisory
              Fact Sheet
 Summary Information:
  1.  Number of Waterbodies
     with Advisories

 S.  Basis of Advisory

 3.  Date Advisory Issued

FDA action level

1st issued in 1991
Lake Wallenpaupack
Anglers are advised to not eat walleye.
Contact!   Robert Frey, PA Bureau of Water Quality Management, (717) 787-9633

     Mercury Advisory
                                  Fact Sheet
 Summary Informations
      Number of Water bod le
      with Advisories


                   March 1994
      Basis of Advisory

      Date Advisory Issued
                General recommendation: The advisory recommends that
                "pregnant women, infants and children should avoid consuming
                fish" trom the waterbodies listed below.
Black River
Combahee River
Coosawhatchle River
Edisto River

Edisto River (North
Edisto River (South
Great Pee Dee River

Intercoastal Waterway
Little Pee Dee River

Lynches River

Pocotaligo River
Santea River

Vaucluse Pond
Waccamaw River









bowfin-1/2 Ib/month; largemouth bass-3/4 Ib/month
largemouth bass-3/4 Ib/month
bowfin-1 1/2 Ib/month
bowfin-1 Ib/month; catfish-3/4 Ib/month; largemouth
bass-3/4 Ib/month
bowfin-1 Ib/month; largemouth bass 1 Ib/month

bowfin-1 1/4 Ib/month; largemouth bass 1/2 Ib/month

bowfin-1 1/4 Ib/month; catfish-1 3/4 Ib/month;
largemouth bass-1 Ib/month; red ear sunfish-2 3/4 Ib/
bluegill, sunfish-3 3/4 Ib/month; bowfin-2 Ib/month;
largemouth bass-1 Ib/month
bowfin-1/2 Ib7month; catfish-1/2 Ib/month; largemouth
bass-1 12. Ib/month
bowfin-3/4 Ib/month; catfish-1 1/2 Ib/month; large-
mouth bass-1 Ib/month
bowfin-3/4 Ib/month; largemouth bass 3/4 Ib/month
bowfin-2 1/4 Ib/month; catfish-5 1/2 lb./month;
largemouth bass-3 3/4 Ib/month
largemouth bass-1 1/2 Ib/month
bluegill, sunfish-3 1/2 Ib/month; bowfin-1 1/4 Ib/month;
largemouth bass-3/4 Ib/month; red ear sunfish-3 1/4

Unknown; probably

Russ Scherer, SC Department of Health and Environmental Control, (803) 734-5296

     Mercury Advisory
                               Fact Sheet
 Summary Information:
  1.   Number of WaterbodU
      with Advisor!*
      Basis of Advisory

      Dale Advisory Issued
                 FDA action level

                 1st issued in 1981
North Fork of the
Holston River

East Fork of Poplar



Do not eat fish from these waters.

Do not eat fish from these waters.

An Industry with a
waste pond that
historically leaked
Oak Ridge
Department of
Energy Reserva-
tion discharges
into the creek.
The facility is
leaking mercury.
Greg Denton, TN Department of Environment and Conservation, (615) 532-0625

     Mercury Advisory
               Fact Sheet
Summary Information:
     Number of Waterbodles
     with Advisories
FDA action level and risk assessment

1st issued in 1988
     Basis of Advisory

     Date Advisory Issued
LaVaca Bay
Do not eat fish from these waters.
(Superfund site)
Contacts   David Sager, Texas Parks and Wildlife Department, (512) 389-4800

     Mercury Advisory
                              Fact Sheet
 Summary Informations
 1.  Number of Wfaferbodies
     with Advisories
 2.  Basis of Advisory
 3.  Date Advisory Issued
                 FDA action level
                 May 4,1990
Lake Champlain and its
tributaries up to first


Walleye-No more than one meal/month. Women of
childbearing age, infants, and children under 15
should not eat any walleye.

Natural sources,
past industrial
discharges, and
John Hall, Vermont Fish and Wildlife, (802) 241-3700

       Mercury Advisory
                                                Fact Sheet
  Summary Informations
Numbor of Waterbodles
with Advisories            2
Basis of Advisory

Dato Advisory Issued
    FDA action level

    1st issued in 1974
 Advisory Specif less
 North Fork of the
 South Fork of the
 Shenandoah, and
                           Taking fish from Saltville to the VA/TN line for human
                           consumption is prohibited.
Limits consumption of fish to no more than one meal
per week from these waters (from footbridge at E.I.
DuPont at Waynesboro to the Page/Warren County
line). Small children and pregnant women should not
eat any fish from these waters.
                                                                        Point source
                                                                        contributions from
Contacts    Dr. Peter Sherertz, Virginia Department of Health, (804) 786-1763

       Mercury Advisory
                                                       Pact Sheet
Summary Informations
Number of Water bodies
with Advisor!*
       Basis of Advisory

       Date Advisory Issued
      230 waterbodies throughout the state including inland
      lakes and rivers, and the Great Lakes


      1st issued in 1971; Issued another advisory for inland
      lakes in 1982, reissued in 1986; currently under review.
               Inland lakes
               and rivers
Group 1:  Pregnant women should eat no more than one
meal/month of listed fish. Everyone else may eat
unlimited amounts.

Group 2:  Pregnant or breast-feeding women, women
who plan to have children, and children under 15 should
not eat listed fish. Everyone else should eat no more
than 26 meals/year. Eat no more than 13 of these 26
meals in one month.

Group 3:  Pregnant or breast-feeding women, women
who plan to have children, and children under 15 should
not eat listed fish. Everyone else should eat no more
than 13 meals/year. Eat no more than 7 of these 13
meals in any one month.

Group 4:  No one should eat these fish.
In the past,
sources may have
been from wood
pulp in paper mills
or industrial waste.
Currently, there
are two major
sources of
airborne mercury:
latex housepaint
and emissions
from coal-burning
power plants.
GommentSB   Species affected: walleye, musky, largernouth bass, yellow perch, northern pike, smallmouth bass,
flathead catfish, sturgeon, black crappie, rock bass, channel catfish.

Group 1: Skin-on fillet samples average <0.5 ppm mercury; also can consider a certain length.
Group 2: Skin-on fillet samples average 0.5-0.75 ppm mercury; also can consider a certain lemgth.
Group 3: Skin-on fillet samples average 0.75-1.0 ppm mercury; also can consider a certain length.
Group 4: Skin-on fillet samples average >1.0 ppm mercury; also can consider a certain length.
Contacts     Jim Amrhein, Wl Department of Natural Resources, (608) 266-5325