Human Health Criteria - Methylmercury                           Wysiwyg //18/http //www epa.gov/waterscience/cnteria/methylinercury/factsheet htm
              Office of Water     "                           FACT S
                    United States               Office of Water    EPA-823-F-01-001
                    Environmental Protection      4304           January 2001
                    Agency
                   Water Quality Criterion for the Protection of Human

                   Health:  Methylmercury


                   Summary

                   The U.S. Environmental Protection Agency (EPA) is announcing the availability of a
                   recommended fish tissue residue criterion for methylmercury to protect human
                   health. This water quality criterion describes the maximum advisable concentration
                   of methylmercury in freshwater and estuarine fish and shellfish tissue to protect
                   consumers offish and shellfish among the general population. EPA expects the
                   criterion recommendation to be used as guidance by States, authorized Tribes, and
                   EPA in establishing or updating water quality standards for waters of the United
                   States and in issuing fish and shellfish consumption advisories. Because consumption
                   of contaminated fish and shellfish is the primary route of human exposure to
                   methylmercury, EPA is expressing this water quality criterion as a fish and shellfish
                   tissue value rather than as a water column value. EPA is providing suggested
                   approaches for relating this criterion to water column concentrationsT and also plans
                   to develop more  detailed guidance to help water quality managers implement the
                   methylmercury criterion in water pollution control programs.

                   What are human health water quality criteria?

                   Human health water quality criteria are numeric values we believe will protect human
                   health for pollutant concentrations in aquatic media, such as ambient waters and
                   edible tissue EPA publishes water quality criteria under the authority of Section
                   304(a) of the Clean Water Act (CWA) based solely on data and scientific judgments
                    about the relationship between pollutant concentrations and environmental and
                    human health effects  CWA Section 303(c) and its implementing regulations require
                    states and authorized tribes to adopt water quality criteria to protect designated uses
                    in their water quality standards EPA's recommended section 304(a) water quality
                    criteria may guide States and authorized Tribes in establishing water quality
                    standards The resulting standards may serve as a basis for controlling discharges or
                    releases of pollutants EPA's recommended human health water quality criteria are
                    not regulations themselves, and do not do not impose legally binding requirements.
                    EPA may change the section 304(a) water quality criteria in the future.

                    How does mercury accumulate in fish and shellfish?

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Human Health Criteria - Mcthylmercury                            Wysiwyg //18/http //www epa gov/waterscience/cntena/methylmercury/factsheet htn:


                    Mercury is found in the environment as a result of natural and human activities. The
                    amount of mercury that cycles in the environment has increased since the industrial
                    age. The main source of mercury is air emissions from power generation and other
                    industrial and waste disposal activities. During its movement among the atmosphere,
                    land, and water, mercury undergoes a series of complex chemical transformations
                    One of the products of these transformations is an organic form called
                    methylmercury. Methylmercury is easily absorbed into the living tissue of aquatic
                    organisms and  is not easily eliminated Therefore, it accumulates in predators The
                    degree to which mercury is transformed into methylmercury  and transferred up the
                    food chain through bioaccumulation depends on many site-specific factors (such as
                    water chemistry and the complexity of the food web) through processes that are not
                    completely understood

                    What adverse effects on human health are related to mercury?

                    Methylmercury is highly toxic to mammals, including people, and causes a number of
                    adverse effects Health studies and information showing neurotoxicity, particularly in
                    developing organisms, are most abundant. The brain is the most sensitive organ for
                    which suitable  data are available to quantify a dose-response relationship. A recent
                    study by the National Academy of Science concluded that the population at highest
                    risk is the children of women who consume large amounts offish and seafood during
                    pregnancy, and that the risk to that population is likely to be sufficient to result in an
                    increase in the  number of children who have to struggle to keep up in school and
                    who might require remedial classes or special education.

                    What actions  reduce health risks?

                    States, Tribes,  and Territories have primary responsibility for protecting their
                    residents from the risks of eating contaminated noncommercially-caught fish and
                    wildlife. They  do this by issuing fish consumption advisories for the general
                    population (including recreational and subsistence fishers) and for sensitive
                    subpopulations (such as pregnant women, nursing mothers,  and children) These
                    advisories inform the public that unacceptable concentrations of chemical
                    contaminants have been found in local fish and wildlife. They also recommend
                    limiting or avoiding consumption of certain fish and wildlife species from specific
                    waterbodies or, in some  cases, from specific waterbody types (e.g, all lakes). Given
                    the ongoing atmospheric sources of mercury and the long-term presence of mercury
                    in the environment, the most effective way to protect public health for the next few
                    decades will be issuing fish consumption advisories to ensure the public knows what
                    level offish from specific waters is safe to eat

                    How is the methylmercury criterion derived?

                    To assess health risks, EPA developed a reference dose that is a scientifically
                    justifiable maximum level of exposure to protect public health from all toxic effects
                    EPA based the methylmercury criterion on a new reference  dose that protects all
                    exposed populations. EPA also updated the exposure assessment and relative source
                    contribution following the recently published 2000 Human Health Methodology The
                    resulting criterion of 0 3 mg methylmercury/kg in fish tissue should not be exceeded
                    to protect the  health  of consumers of noncommercial freshwater/estuarine fish EPA


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Human Health Criteria - Methylmercury                            Wysiwyg //18/http.//www epa gov/waterscience/cnteria/methylmercury/facuheet htm


                   has taken into account the fact that consumers of freshwater/estuarine fish are also
                   consumers of marine fish

                   EPA suggests three approaches that can be used to translate fish tissue
                   methylmercury concentrations into concentrations of methylmercury found in the
                   water column:

                        Calculate site-specific bioaccumulation factors based on data collected from a
                         specific waterbody;
                        Calculate site-specific bioaccumulation factors based on computer models, and
                        Use experimentally-derived bioaccumulation factors that are based on field
                         data published in the criteria.

                    EPA developed a set of empirically- derived bioaccumulation factors in the initial
                    efforts to derive a revised ambient water quality criteria for methylmercury EPA has
                    also derived factors to translate methylmercury in water to its total mercury
                    equivalent.

                    How can this criterion help control mercury pollution?

                    The United States needs to establish effective source control and management
                    programs in the coming years to begin to recover from the widespread mercury
                    contamination in our aquatic environments  Such actions will hopefully reduce
                    mercury contamination so that fish consumption advisories can be removed. EPA
                    expects the criterion recommendation to be used as a guide by States, authorized
                    Tribes, and EPA in establishing or updating water quality standards that may serve
                    as a basis for pollutant source control and for fish and shellfish consumption
                    advisories.

                    What future activities are related to  this criterion?

                    EPA recognizes and emphasizes that States and authorized Tribes will need
                    additional specific procedures and water quality program guidance to implement the
                    water quality criteria they adopt based  on this guidance. These procedures include,
                    but are not limited to, procedures for translating methylmercury concentrations in
                    fish to total mercury concentrations in ambient surface water or effluent, and
                    procedures for setting permit limits and calculating Total Maximum Daily Loads
                    EPA is developing these procedures and guidance documents for this water quality
                    criterion.

                    How do I obtain a copy of the criteria document?

                    You can get copies of the criterion document titled Water Quality Criterion for the
                    Protection of Hitman Health: Methylmercury from EPA's National Service Center
                    for Environmental Publications (NSCEP) by calling 1-800-490-9198. Or you can get
                    the document and related fact sheet from EPA's web site at
                    http://www.epa gov/waterscience/standards/methylmercury/.

                    Where can I get more information?
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Human Health Criteria - Methylmeroury                           Wysiwyg //18/http //www epa gov/waterscicnce/critena/methylmercury/factsheet htm


                   For general questions about the criterion, contact Mary Manibusan, USEPA, Health
                   and Ecological Criteria Division, (Mail Code 4304), Office of Science and
                   Technology, 1200 Pennsylvania Avenue, NW, Washington, DC 20460, (202)
                   260-3688, fax (202) 260-1036, e-mail manibusan mary@.epa gov.

                   For specific issues about mercury bioaccumulation , contact. Erik Winchester,
                   Health and Ecological Criteria Division, (Mail Code 4304), Office of Science and
                   Technology, 1200 Pennsylvania Avenue, NW, Washington, DC 20460, (202)
                   260-6107

                   For questions  about implementing the criterion  contact William Morrow, USEPA,
                    Standards and Health Protection Division, (Mail Code 4305), Office of Science and
                   Technology, 1200 Pennsylvania Avenue, NW, Washington, DC 20460, (202)
                   260-3657


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                                           Revised  Wednesday, January 03,2001 17.04.54
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