Contaminant Candidate
List Regulatory
Determination Support
Document for
Manganese
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Contaminant Candidate List
Regulatory Determination Support Document
for Manganese
U.S. Environmental Protection Agency
Office of Water (4607M)
Standards and Risk Management Division
Washington, DC 20460
http://www.epa.gov/SAFEWATER/ccl/cclregdetennine.html
EPA-815-R-03-12
July 2003
f\ Printed on Recycled Paper
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Disclaimer
This document is designed to provide supporting information regarding the
regulatory determinations for manganese as part of the Contaminant
Candidate List (CCL) evaluation process. This document is not a regulation,
and it does not substitute for the Safe Drinking Water Act (SDWA) or the
Environmental Protection Agency's (EPA's) regulations. Thus, it cannot
impose legally-binding requirements on EPA, States, or the regulated
community, and may not apply to a particular situation based upon the
circumstances. Mention of trade names or commercial products does not
constitute endorsement or recommendation for use.
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Regulatory Determination Support Document for Manganese July 2003
ACKNOWLEDGMENTS
This document was prepared in support of the EPA Office of Ground Water and Drinking Water's
regulatory determination for manganese as part of the Contaminant Candidate List (CCL) evaluation
process. Karen Wirth and Tom Carpenter served as EPA's Co-Team Leaders for the CCL regulatory
determination process and Ephraim King as Standards and Risk Management Division Director.
Harriet Colbert served as Work Assignment Manager. The CCL Work Group provided technical
guidance throughout. In particular, Karen Wirth, Dan Olson, and Joyce Donohue provided scientific
and editorial guidance. External expert reviewers and many stakeholders provided valuable advice to
improve the CCL program and this document. The Cadmus Group, Inc., served as the primary
contractor providing support for this work. The major contributions of Matt Collins, Emily Brott,
Ashton Koo, Richard Zeroka, and Brent Ranalli are gratefully acknowledged. George Hallberg served
as Cadmus' Project Manager.
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Regulatory Determination Support Document for Manganese July 2003
USEPA, Office of Water Report: EPA 815-R-03-012, July 2003
CONTAMINANT CANDIDATE LIST
REGULATORY DETERMINATION SUPPORT DOCUMENT
FOR MANGANESE
EXECUTIVE SUMMARY
Manganese was a 1998 Contaminant Candidate List (CCL) regulatory determination priority
contaminant. Manganese was one of the contaminants considered by the U.S. Environmental
Protection Agency (EPA) for a regulatory determination. The available data on occurrence, exposure,
and other risk considerations suggest that regulating manganese may not present a meaningful
opportunity to reduce health risk. EPA presented preliminary CCL regulatory determinations and
further analysis in the June 3, 2002 Federal Register (FR) Notice (USEPA, 2002; 67 FR 38222), and
confirmed the final CCL regulatory determinations in the July 18, 2003 Federal Register Notice
(USEPA, 2003a; 68 FR 42898).
To make this regulatory determination for manganese, EPA used approaches guided by the
National Drinking Water Advisory Council's (NDWAC) Work Group on CCL and Six-Year Review.
The Safe Drinking Water Act (SDWA) requirements for National Primary Drinking Water Regulation
(NPDWR) promulgation guided protocol development. The SDWA Section 1412(b)(l)(A) specifies
that the determination to regulate a contaminant must be based on a finding that each of the following
criteria are met: (i) "the contaminant may have adverse effects on the health of persons"; (ii) "the
contaminant is known to occur or there is substantial likelihood that the contaminant will occur in public
water systems with a frequency and at levels of public health concern"; and (iii) "in the sole judgement
of the Administrator, regulation of such contaminant presents a meaningful opportunity for health risk
reduction for persons served by public water systems." Available data were evaluated to address the
three statutory criteria.
Manganese is a naturally occurring element that is a component of over 100 minerals. Of the heavy
metals, it is surpassed in abundance only by iron (Agency for Toxic Substances and Disease Registry
(ATSDR), 1997). Because of the natural release of manganese into the environment by the weathering
of manganese-rich rocks and sediments, manganese occurs ubiquitously at low levels in soil, water, air,
and food. In the United States, most manganese ore is smelted to produce ferromanganese, which is a
manganese-iron alloy (ATSDR, 1997). The latter is used primarily in the production of steel to
improve stiffness, hardness, and strength. Other manganese compounds are produced through
reactions of various elements and compounds with either manganese ores or ferromanganese (ATSDR,
1997). Some common manganese compounds include manganese chloride, manganese sulfate,
manganese (JJ, HI) oxide, manganese dioxide, and potassium permanganate (see Table 2-1). These
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Regulatory Determination Support Document for Manganese July 2003
compounds are used in a variety of products and applications including water and wastewater
treatment, matches, dry-cell batteries, fireworks, fertilizer, varnish, livestock supplements, and as
precursors for other manganese compounds (ATSDR, 1997). Releases of manganese to the
environment, reported through the Toxic Release Inventory (TRI), are widespread.
Neither manganese nor any manganese compounds are regulated in drinking water. However, a
non-enforceable guidance level for aesthetic quality, a Secondary Maximum Contaminant Level
(SMCL) of 0.05 mg/L, does exist for manganese (ATSDR, 1997). Manganese and manganese
compounds are regulated and/or monitored by other federal programs, including the National Pollution
Discharge Elimination System (NPDES), the Clean Air Act Hazardous Air Pollutants list, the
Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), and the TRI.
Other federal agencies and organizations have issued recommendations for occupational exposure.
Low-level manganese occurrence in ambient waters and stream bed sediments monitored by the
United States Geological Survey's (USGS) National Water Quality Assessment (NAWQA) program
is ubiquitous, with detections approaching 100% of surface water sites and greater than 62% of ground
water sites. Stream bed sediments and aquatic biota tissues show detections of 100%, by sample and
by site. Urban basins generally have more surface and ground water manganese detections that are
greater than the health reference level (HRL) of 0.30 mg/L than basins in other land use categories.
Higher median and 99th percentile concentrations are also typical in urban basins. Although manganese
detection frequencies are high in ambient waters, stream bed sediments, and aquatic biota tissue,
manganese occurrence at levels of public health concern is low.
Manganese has also been detected in ground water public water systems (PWSs) samples
collected through the National Inorganic and Radionuclide Survey (MRS). Occurrence estimates are
relatively high with approximately 68% of all samples showing detections, affecting about 55% of the
national population served. Only about 3% of the MRS systems, however, showed occurrence levels
exceeding the HRL of 0.30 mg/L, affecting approximately 2.3 million people nationally. Additional data
from ground water and surface water PWSs from select States were examined through independent
analyses and also show substantial low-level manganese occurrence.
There is evidence that manganese may have adverse health effects in humans at high doses through
inhalation, most importantly as a neurotoxin (producing ataxia, or coordination impairment, anxiety,
dementia, a "mask-like" face, involuntary movements, or a syndrome similar to Parkinson's disease).
Nevertheless, oral exposure at levels common in Western diets is not known to produce adverse health
effects. In addition, because manganese is an essential nutrient, concern over potential toxic effects
from high oral exposure must be balanced against concern for adverse effects from manganese
deficiency. The level of manganese detected in PWSs is far below the average daily intake of
manganese through non-water sources.
IV
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Regulatory Determination Support Document for Manganese July 2003
Because manganese is generally not considered to be very toxic when ingested with the diet, and
since drinking water accounts for a relatively small proportion of manganese intake, regulation would
not likely present a meaningful opportunity for health risk reduction for persons served by PWSs.
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Regulatory Determination Support Document for Manganese July 2003
TABLE OF CONTENTS
ACKNOWLEDGMENTS i
EXECUTIVE SUMMARY iii
TABLE OF CONTENTS vii
LIST OF TABLES ix
1.0 INTRODUCTION 1
1.1 Purpose and Scope 1
1.2 Statutory Framework/Background 1
1.3 Statutory History of Manganese 2
1.4 Regulatory Determination Process 3
1.5 Determination Outcome 4
2.0 CONTAMINANT DEFINITION 5
2.1 Physical and Chemical Properties 5
2.2 Environmental Fate/Behavior 5
3.0 OCCURRENCE AND EXPOSURE 6
3.1 Occurrence 6
3.1.1 Use and Environmental Release 6
3.1.2 Environmental Release 8
3.2 Ambient Occurrence 12
3.2.1 Data Sources and Methods 12
3.2.2 Results 13
3.3 Drinking Water Occurrence 15
3.3.1 Analytical Approach 15
3.3.1.1 National Inorganic and Radionuclide Survey 15
3.3.1.2 Supplemental IOC Data 15
3.3.1.3 Data Management 17
3.3.1.4 Occurrence Analysis 17
3.3.1.5 Additional Drinking Water Data from 1996 AWWA Survey 19
3.3.2 Results 20
3.3.2.1 Occurrence in AWWA PWSs 21
4.0 HEALTH EFFECTS 24
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Regulatory Determination Support Document for Manganese July 2003
4.1 Hazard Characterization and Mode of Action Implications 24
4.2 Dose-Response Characterization and Implications in Risk Assessment 25
4.3 Relative Source Contribution 26
4.4 Sensitive Populations 26
4.5 Exposure and Risk Information 27
4.6 Conclusion 27
5.0 TECHNOLOGY ASSESSMENT 28
5.1 Analytical Methods 28
5.2 Treatment Technology 28
6.0 SUMMARY AND CONCLUSIONS - DETERMINATION OUTCOME 30
REFERENCES 33
APPENDIX A: Abbreviations and Acronyms 37
vui
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Regulatory Determination Support Document for Manganese July 2003
LIST OF TABLES
Table 2-1: Physical and chemical properties 7
Table 3-1: Imports of manganese and ferromanganese to the U.S. (thousand metric tons, gross weight^
Table 3-2: Manganese manufacturers and processors by State 10
Table 3-3: Environmental releases (in pounds) for manganese in the United States, 1988-1998
11
Table 3-4: Environmental releases (in pounds) for manganese compounds in the United States, 1988-
1998 11
Table 3-5: Manganese detections and concentrations in streams and ground water 16
Table 3-6: Manganese detections and concentrations in bed sediments and aquatic biota tissues (all
sites) 16
Table 3-7: Manganese occurrence in ground water systems (MRS survey) 21
Table 3-8: Occurrence summary of ground and surface water systems, by State, for manganese
23
Table 5-1: Analytical Methods for Manganese 29
rx
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Regulatory Determination Support Document for Manganese July 2003
1.0 INTRODUCTION
1.1 Purpose and Scope
This document presents scientific data and summaries of technical information prepared for, and
used in, the United States Environmental Protection Agency's (EPA) regulatory determination for
manganese. Information regarding manganese's physical and chemical properties, environmental fate,
occurrence and exposure, and health effects is included. Analytical methods and treatment technologies
are also discussed. Furthermore, the regulatory determination process is described to provide the
rationale for the decision.
1.2 Statutory Framework/Background
The Safe Drinking Water Act (SDWA), as amended in 1996, requires the EPA to publish a list of
contaminants (referred to as the Contaminant Candidate List, or CCL) to assist in priority-setting
efforts. The contaminants included on the CCL were not subject to any current or proposed National
Primary Drinking Water Regulations (NPDWR), were known or anticipated to occur in public water
systems, and were known or suspected to adversely affect public health. These contaminants therefore
may require regulation under SDWA. The first Drinking Water CCL was published on March 2, 1998
(USEPA, 1998b; 63 FR 10273), and a new CCL must be published every five years thereafter.
The 1998 CCL contains 60 contaminants, including 50 chemicals or chemical groups, and 10
microbiological contaminants or microbial groups. The SDWA also requires the Agency to select 5 or
more contaminants from the current CCL and determine whether or not to regulate these contaminants
with an NPDWR. Regulatory determinations for at least five contaminants must be completed 3l/2
years after each new CCL.
Language in SDWA Section 1412(b)(l)(A) specifies that the determination to regulate a
contaminant must be based on a finding that each of the following criteria are met:
Statutory Finding i: the contaminant may have adverse effects on the health of persons;
Statutory Finding ii: the contaminant is known to occur or there is substantial likelihood that
the contaminant will occur in public water systems with a frequency and at levels of public
health concern; and
Statutory Finding Hi: in the sole judgement of the Administrator, regulation of such
contaminant presents a meaningful opportunity for health risk reduction for persons served
by public water systems.
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Regulatory Determination Support Document for Manganese July 2003
The geographic distribution of the contaminant is another factor evaluated to determine whether it
occurs at the national, regional, or local level. This consideration is important because the Agency is
charged with developing national regulations, and it may not be appropriate to develop NPDWRs for
regional or local contamination problems.
EPA must determine if regulating this CCL contaminant will present a meaningful opportunity to
reduce health risk based on contaminant occurrence, exposure, and other risk considerations. The
Office of Ground Water and Drinking Water (OGWDW) is charged with gathering and analyzing the
occurrence, exposure, and risk information necessary to support this regulatory decision. The
OGWDW must evaluate when and where this contaminant occurs, and what would be the exposure
and risk to public health. EPA must evaluate the impact of potential regulations as well as determine the
appropriate measure(s) for protecting public health.
For each of the regulatory determinations, EPA first publishes in the Federal Register the draft
determinations for public comment. EPA responds to the public comments received, and then finalizes
regulatory determinations. If the Agency finds that regulations are warranted, the regulations must then
be formally proposed within twenty-four months, and promulgated by eighteen months later. EPA has
determined that there is sufficient information to support a regulatory determination for manganese.
1.3 Statutory History of Manganese
While neither manganese nor any of its compounds are regulated in drinking water, a non-
enforceable guidance level for aesthetic quality, a Secondary Maximum Contaminant Level (SMCL) of
0.05 mg/L, does exist (ATSDR, 1997). Also, manganese and manganese compounds are regulated
and/or monitored by other federal programs. The discharge of manganese to surface waters is
regulated as total manganese under the National Pollution Discharge Elimination System (NPDES)
(ATSDR, 1997). Both manganese and manganese compounds are listed as a Hazardous Air Pollutants
under Section 112(b) of the Clean Air Act and subject to Best Available Control Technology limits
(USEPA, 2000f). Also, the Comprehensive Environmental Response, Compensation, and Liability Act
(CERCLA or "Superfund") includes manganese compounds as hazardous substances, although no
reporting thresholds are assigned to this broad class (USEPA, 1998a). Manganese is also a Toxic
Release Inventory (TRI) chemical. The TRI was established by the Emergency Planning and
Community Right-to-Know Act (EPCRA), which requires certain industrial sectors to publicly report
the environmental release or transfer of chemicals included in this inventory.
Finally, manganese and some of its compounds are listed as air contaminants by the Occupational
Safety and Health Administration (OSHA). This listing establishes different permissible exposure limits
(PELs) for various manganese compounds to regulate workplace exposure (ATSDR, 1997).
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Regulatory Determination Support Document for Manganese July 2003
1.4 Regulatory Determination Process
In developing a process for the regulatory determinations, EPA sought input from experts and
stakeholders. EPA asked the National Research Council (NRC) for assistance in developing a
scientifically sound approach for deciding whether or not to regulate contaminants on the current and
future CCLs. The NRC's Committee on Drinking Water Contaminants recommended that EPA: (1)
gather and analyze health effects, exposure, treatment, and analytical methods data for each
contaminant; (2) conduct a preliminary risk assessment for each contaminant based on the available
data; and (3) issue a decision document for each contaminant describing the outcome of the preliminary
risk assessment. The NRC noted that in using this decision framework, EPA should keep in mind the
importance of involving all interested parties.
One of the formal means by which EPA works with its stakeholders is through the National
Drinking Water Advisory Council (NDWAC). The NDWAC comprises members of the general
public, State and local agencies, and private groups concerned with safe drinking water, and advises
the EPA Administrator on key aspects of the Agency's drinking water program. The NDWAC
provided specific recommendations to EPA on a protocol to assist the Agency in making regulatory
determinations for current and future CCL contaminants. Separate but similar protocols were
developed for chemical and microbial contaminants. These protocols are intended to provide a
consistent approach to evaluating contaminants for regulatory determination, and to be a tool that will
organize information in a manner that will communicate the rationale for each determination to
stakeholders. The possible outcomes of the regulatory determination process are: a decision to
regulate, a decision not to regulate, or a decision that some other action is needed (e.g., issuance of
guidance).
The NDWAC protocol uses the three statutory requirements of SDWA Section 1412(b)(l)(A)(i)-
(iii) (specified in section 1.2) as the foundation for guiding EPA in making regulatory determination
decisions. For each statutory requirement, evaluation criteria were developed and are summarized
below.
To address whether a contaminant may have adverse effects on the health of persons (statutory
requirement (i)), the NDWAC recommended that EPA characterize the health risk and estimate a
health reference level for evaluating the occurrence data for each contaminant.
Regarding whether a contaminant is known to occur, or whether there is substantial likelihood that
the contaminant will occur, in public water systems with a frequency, and at levels, of public health
concern (statutory requirement (ii)), the NDWAC recommended that EPA consider: (1) the actual and
estimated national percent of public water systems (PWSs) reporting detections above half the health
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Regulatory Determination Support Document for Manganese July 2003
reference level; (2) the actual and estimated national percent of PWSs with detections above the health
reference level; and (3) the geographic distribution of the contaminant.
To address whether regulation of a contaminant presents a meaningful opportunity for health risk
reduction for persons served by public water systems (statutory requirement (iii)) the NOW AC
recommended that EPA consider estimating the national population exposed above half the health
reference level and the national population exposed above the health reference level.
The approach EPA used to make regulatory determinations followed the general format
recommended by the NRC and the NOW AC to satisfy the three SDWA requirements under Section
1412(b)(l)(A)(i)-(iii). The process was independent of many of the more detailed and comprehensive
risk management factors that will influence the ultimate regulatory decision making process. Thus, a
decision to regulate is the beginning of the Agency regulatory development process, not the end.
Specifically, EPA characterized the human health effects that may result from exposure to a
contaminant found in drinking water. Based on this characterization, the Agency estimated a health
reference level (HRL) for each contaminant.
For each contaminant EPA estimated the number of PWSs with detections >/^HRL and >HRL, the
population served at these benchmark values, and the geographic distribution, using a large number of
occurrence data (approximately seven million analytical points) that broadly reflect national coverage.
Round 1 and Round 2 Unregulated Contaminant Monitoring (UCM) data, evaluated for quality,
completeness, bias, and representativeness, were the primary data used to develop national occurrence
estimates. Use and environmental release information, additional drinking water data sets (e.g., State
drinking water data sets, EPA National Pesticide Survey, and Environmental Working Group data
reviews), and ambient water quality data (e.g., National Water Quality Assessment (NAWQA), State
and regional studies, and the EPA Pesticides in Ground Water Database) were also consulted.
The findings from these evaluations were used to determine if there was adequate information to
evaluate the three SDWA statutory requirements and to make a determination of whether to regulate a
contaminant.
1.5 Determination Outcome
After reviewing the best available public health and occurrence information, EPA has made a
determination not to regulate manganese with an NPDWR. This decision is based on the finding that
since the toxicity of manganese by oral ingestion is low, regulation of manganese in drinking water may
not present a meaningful opportunity for health risk reduction for persons served by public water
systems. All CCL regulatory determinations and further analysis are formally presented in the Federal
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Regulatory Determination Support Document for Manganese July 2003
Register Notices (USEPA, 2002; 67 FR 38222, and USEPA, 2003a; 68 FR 42898). The following
sections summarize the data used by the Agency to reach its decision.
2.0 CONTAMINANT DEFINITION
Manganese is a naturally occurring element that constitutes approximately 0.1% of the earth's crust.
It does not occur in the environment in its pure metal form, but is ubiquitous as a component of over
100 minerals including many silicates, carbonates, sulfides, oxides, phosphates, and borates (ATSDR,
1997). It occurs ubiquitously naturally at low levels in soil, water, air, and food. Of the heavy metals,
manganese is surpassed in abundance only by iron (ATSDR, 1997).
Manganese compounds are also produced in the United States through a variety of industrial
processes. Manganese ore is commonly smelted to produce ferromanganese, which is a manganese-
iron alloy (ATSDR, 1997). Other manganese compounds produced through reactions of various
elements and compounds with either manganese ores or ferromanganese include manganese chloride,
manganese sulfate, manganese (n, m) oxide, manganese dioxide, and potassium permanganate
(ATSDR, 1997).
2.1 Physical and Chemical Properties
Table 2-1 lists summary information regarding the physical and chemical properties of manganese
and a few of its important compounds. Also included are the Chemical Abstract Service (CAS)
Registry Numbers and molecular formulas.
2.2 Environmental Fate/Behavior
The environmental fate and behavior of manganese depends upon the form found in, or released
into, the environment, and the physical and chemical characteristics of the environment itself. Some
generalities can be made, however, regarding its behavior in air, water, and soil.
Naturally occurring manganese and its compounds, as well as anthropogenically released
manganese, do not evaporate. However, manganese and its compounds do enter the air as particulate
matter through soil erosion and industrial emissions. The half-life of airborne particulate matter is on the
order of days with the smallest particles capable of longer suspension times. Removal of particulate
matter is largely through dryfall, but some is removed by precipitation (ATSDR, 1997).
The transport and partitioning of naturally occurring and anthropogenically released manganese in
water depends upon the solubility of the compound(s) present, which in turn depends upon the Eh
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Regulatory Determination Support Document for Manganese July 2003
(oxidation-reduction potential), pH, and the anions available in solution. Ionic manganese is positively
charged (Mn2+). Manganese is also transported in water as suspended sediment (ATSDR, 1997).
Some of the common manganese compounds are insoluble, but a number of them have low to
moderate solubility (Table 2-1). Though manganese can exist in water in any of four oxidation states,
Mn(n) is the most common and is usually associated with the carbonate anion (CO32") to form MnCO3.
This compound has a relatively low solubility at 65 mg/L (ATSDR, 1997). Manganese may be
oxidized at high pH or Eh and is also subject to microbial activity (ATSDR, 1997).
The mobility of soluble manganese in soil depends upon the cation exchange capacity (CEC) of the
soil and the amount of soil organic matter. A soil with high CEC and rich in organic matter has an
abundance of negatively charged particles to attract manganese cations. These reactions form various
manganese oxides. These oxides are themselves important adsorption sites for other metals (Drever,
1988). Manganese can adsorb to other oxides through ligand exchange reactions (ATSDR, 1997).
At low concentrations, manganese cations that react with negatively charged particles in the soil
(i.e., organic matter, clay) may not be readily released. Also, the oxidation state of manganese may be
altered by microbial activity (ATSDR, 1997).
3.0 OCCURRENCE AND EXPOSURE
This section examines the occurrence of manganese in drinking water. While no complete national
database exists of the occurrence of unregulated or regulated contaminants in drinking water from
public water systems collected under SDWA, this report aggregates and analyzes existing federal and
State data that have been screened for quality, completeness, and representativeness. Populations
served by PWSs exposed to manganese are also estimated, and the occurrence data are examined for
special trends. To augment the incomplete national drinking water data and aid in the evaluation of
occurrence, information on the use and environmental release, as well as ambient occurrence of
manganese, is also reviewed.
3.1 Occurrence
3.1.1 Use and Environmental Release
In the United States, most manganese ore is smelted to produce ferromanganese which is a
manganese-iron alloy (ATSDR, 1997). The latter is used primarily in the production of steel to
improve stiffness, hardness, and strength. The ore is mined in open pit or shallow underground mines,
though little has been mined in the U.S. since 1978 (ATSDR, 1997; USGS, 2000). Almost all of the
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Regulatory Determination Support Document for Manganese
July 2003
Table 2-1: Physical and chemical properties
Identification
,- , »", /
CAS number
Molecular Formula
manganese
7439-96-5
Mn
manganese
chloride
7773-01-5
MnCl2
manganese
sulfate
7785-87-7
MnS04
manganese
(II, III) oxide
1317-35-7
Mn3O4
manganese
dioxide
1313-13-9
Mn02
potassium
permanganate
7722-64-7
KMn04
B^ffpalapd.-Chfnjical-'Propfrtief
Boiling Point
Melting Point
Molecular Weight
Log Koc
Log Kow
Water Solubility
Vapor Pressure
Henry's Law Constant
1,962°C
1,244°C
54.94 g/mol
no data
no data
decomposes
1 mmHg at
1,292°C
no data
1,190 °C
650 °C
125.85 g/mol
no data
no data
723 g/L
at 25 °C
10 mmHg at
778 °C
no data
850 °C
(decomposes)
700 °C
15 1.00 g/mol
no data
no data
520 g/L
at5°C
no data
no data
no data
1,564°C
228.81 g/mol
no data
no data
insoluble
no data
no data
no data
loses oxygen
at 535 °C
86.94 g/mol
no data
no data
insoluble
no data
no data
no data
< 240 °C
(decomposes)
158.04 g/mol
no data
no data
63.8 g/L
at 20 °C
no data
no data
after ATSDR, 1997
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Regulatory Determination Support Document for Manganese
July 2003
manganese ore used in steel production in the U.S. is imported (see Table 3-1; ATSDR, 1997). Large
quantities of ferromanganese are imported as well (USGS, 2000). Table 3-2 provides further
information, by State, of the widespread manufacture and processing of manganese.
Table 3-1: Imports of manganese and ferromanganese to the U.S. (thousand metric tons,
gross weight)
manganese ore
ferromanganese
lf§4
308
-
/*988
499
-
/W9S
394
310
/&&
478
374
/&&
355
304
/if as
332
339
/WS>/
535
325
years 1984 and 1988: ATSDR, 1997
years 1995 to 1999: USGS, 2000
t estimated
Manganese compounds are produced through reactions of various elements and compounds with
either manganese ores or ferromanganese (ATSDR, 1997). Some common manganese compounds
include manganese chloride, manganese sulfate, manganese (n, m) oxide, manganese dioxide, and
potassium permanganate (ATSDR, 1997). Usage of these compounds are varied, implying
widespread environmental release. Significantly, approximately 80% of the potassium permanganate
used in the U.S. is expended in wastewater and drinking water. Manganese dioxide is used in the
production of matches, dry-cell batteries, fireworks, and as a precursor for other manganese
compounds. Manganese chloride is also used as a precursor for other manganese compounds. A
large proportion (60%) of U.S. manganese sulfate is used as a fertilizer, while the remainder is used in
varnish, fungicides, and as a livestock supplement. An organic manganese compound,
methylcyclopentadienyl manganese tricarbonyl (MMT), was used as an anti-knock additive in unleaded
gasoline before it was banned in 1977. However, a 1995 court decision required EPA to re-register
MMT and this process is ongoing (ATSDR, 1997).
3.1.2 Environmental Release
Manganese is listed as a TRI chemical. In 1986, the Emergency Planning and Community Right-
to-Know Act (EPCRA) established the TRI of hazardous chemicals. Created under the Superfund
Amendments and Reauthorization Act (SARA) of 1986, EPCRA is also sometimes known as SARA
Title m. The EPCRA mandates that larger facilities publicly report when TRI chemicals are released
into the environment. This public reporting is required for facilities with more than 10 full-time
employees that annually manufacture or produce more than 25,000 pounds, or use more than 10,000
pounds, of a TRI chemical (USEPA, 1996; USEPA, 2000d).
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Regulatory Determination Support Document for Manganese July 2003
Under these conditions, facilities are required to report the pounds per year of manganese released
into the environment both on- and off-site. The on-site quantity is subdivided into air emissions, surface
water discharges, underground injections, and releases to land (see Table 3-3). For manganese,
releases to land constitute most of the on-site releases, with an abrupt decrease occurring in 1989. It is
unclear whether this sharp decrease is real or a function of changes in TRI reporting requirements in the
late 1980s and early 1990s (see discussion below). Land releases have fluctuated modestly since that
year with no trend evident. Air emissions are also an important mode of on-site release. Though the
first four years of record for air emissions are markedly higher, no trend is apparent for the remainder.
Surface water discharges and underground injection are less significant on-site releases, with
underground injections sharply decreasing in 1994. Low levels of underground injection have
continued to the present. Off-site releases of manganese are considerable. Though in 1990 there is a
large drop when compared to previous years, the late 1990s show a steady increase in pounds
released. These TRI data for manganese were reported from 49 States with the exception of Alaska
and Puerto Rico (USEPA, 2000b).
TRI data are also available for the release of manganese compounds (Table 3-4). Releases to land
again constitute the largest proportion of on-site releases. With the exception of 1997 and 1998,
releases to land have generally decreased over the period of record. Air emissions are also an
important mode of release and no trend is evident in the data. Significantly, surface water discharges
and underground injections are much more important for the compounds than for elemental manganese,
and have been generally increasing (dramatically in some years) since the early 1990s.
Increases in surface water discharges and underground injections have contributed to increases in
total on- and off-site releases in recent years. The latter have returned to, or exceeded, the higher
levels seen in the late 1980s and early nineties. Off-site releases, a large component of total releases,
are also at their highest levels since reporting began in 1988. These TRI data for manganese
compounds were reported from all 50 States (USEPA, 2000b).
Although the TRI data can be useful in giving a general idea of release trends, it is far from exhaustive
and has significant limitations. For example, only industries that meet TRI criteria (at least 10 full-time
employees and manufacture and processing of quantities exceeding 25,000 Ibs/yr, or use of more than
10,000 Ibs/yr) are required to report releases. These reporting criteria do not account for releases
from smaller industries. Threshold manufacture and processing quantities also changed from 1988-
1990 (dropping from 75,000 Ibs/yr in 1988 to 50,000 Ibs/yr in 1989 to its current 25,000 Ibs/yr in
1990) possibly creating misleading data trends. Finally, the TRI data is meant to reflect releases and
should not be used to estimate general exposure to a chemical (USEPA, 2000c; USEPA, 2000a).
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Regulatory Determination Support Document for Manganese
July 2003
Table 3-2: Manganese manufacturers and processors by State
State*
AL
AR
AZ
CA
CO
CT
EL
GA
HI
IA
ID
IL
IN
KS
KY
LA
MA
MD
ME
MI
MN
MO
MS
NC
ND
NE
NH
NJ
NM
NV
NY
OH
OK
OR
PA
PR
RI
SC
SD
TN
TX
UT
VA
WA
WI
WV
WY
Number offaeiKtiei
* *^
23
15
2
39
12
11
11
20
1
32
1
71
63
4
29
5
17
9
62
12
27
7
24
1
10
7
16
1
2
37
93
24
13
97
3
1
23
3
24
36
11
23
19
67
11
1
Range of maximum amount*
on site in£|hou§&ndt' fff ^ ,-
0-50,000
0-1,000
1-100
0-1,000
0-100
0-1,000
1-1,000
0-1,000
1-10
1-10,000
10-100
0-10,000
0-10,000
0-1,000
0-10,000
0-1,000
0-1,000
0-1,000
1-1000
0-50,000
0-1,000
0-1,000
1-100
0-1,000
10-100
0-50,000
0-100
1,000
10-100
0-100
0-10,000
0-50,000
0-1,000
0-10,000
0-100,000
0-1,000
10-100
0-1,000
0-1,000
0-10,000
0-10,000
0-10,000
0-1,000
0-1,000
0-1,000
0-10,000
10-100
^u9$yities and, wet"
1,2,3,4,5,6,7,8,9,11,12,13
1,2,3,4,5,7,8,9,10,11,12,13
1,2,3,4,5,6,7,8,9
1,2,3,4,5,6,7,8,9,10,11
2,3,4,9,10
1,5,7,9
1,5,8,9,10,13
1,2,3,5,7,8,9,10,12
2,3,8,13
1,2,3,4,5,7,8,9,12
1,4
1,2,3,4,5,6,7,8,9,10,11,12
1,3,4,5,6,7,8,9,10,11,12,13
1,5,7,8,9
1,2,3,4,5,6,7,8,9,10,12,13
1,2,3,5,6,7,8,9,13
8,9,10,12
1,2,3,4,6,8,9,10,12
7,9,13
1,2,3,4,5,7,8,9,10,11,12,13
1,3,5,8,9,10,12,13
1,2,3,5,7,8,9,12,13
8,9
1,2,3,5,8,9,10,12
1,5,9,11
1,2,3,5,8,9,10,12
8,9,13
1,2,3,4,5,7,8,9,10,12
9
1 2357,13
1,2,3,4,5,7,8,9,10,13
1,2,3,4,5,6,7,8,9,10,11,12
1,3,4,5,7,8,9,10,12,13
2,3,8,9,10
1,2,3,4,5,6,7,8,9,10,11,12
8,9,11
9
1,5,7,8,9,10
1,5,8,9,12
1,2,3,4,5,6,7,8,9,10,11,12
1,2,3,4,5,6,7,8,9,10,11,12
1,2,3,5,6,7,8,9,11
1,5,8,9,10,11,12,13
2,3,7,8,9,10
1,2,3,5,6,7,8,9,10,12,13
1,2,3,4,5,7,8,9,10,13
10.12
aPost office State abbreviations used
Data in TRI are maximum amounts on site at each facility
cActivity and Use Codes:
1. Produce
2. Import
3. For on-site use/processing
4. For sale/distribution
5. As a byproduct
6. As an impurity
7. As a reactant
source: ATSDR, 1997 compilation of 1991 TRI data
8. As a formulation component
9. As a product component
10. For repackaging
11. As a chemical processing aid
12. As a manufacturing aid
13. Ancillary or other uses
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Regulatory Determination Support Document for Manganese
July 2003
Table 3-3: Environmental releases (in pounds) for manganese in the United States, 1988-
1998
Year
,,--"
1998
1997
1996
1995
1994
1993
1992
1991
1990
1989
1988
/On^Site Releases
Air
Emissions
/
52,820,578
50,141,026
40,334,426
41,832,058
38,228,464
47,763,821
63,490,137
66,559,047
83,331,787
85,191,013
84,227,842
/Off-Sfte
' JLeleases
45,269,882
47,233,186
33,543,677
25,994,951
25,840,954
22,780,860
17,297,544
27,250,630
35,789,554
33,004,908
20,670,921
Total On-A
/' Ortsite
Releases ..
111,884,004
117,539,423
77,841,658
72,386,427
67,993,597
73,563,600
83,623,022
96,066,393
122,122,054
121,956,833
114,197,765
source: USEPA, 20006
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Regulatory Determination Support Document for Manganese July 2003
In summary, manganese and many of its compounds are naturally occurring and found at low levels
in soil, water, air, and food. Furthermore, manganese compounds are produced in the United States
from manganese ore and are in widespread use. Most ferromanganese is used in steel production,
while other manganese compounds are used in a variety of applications, from fertilizers and industrial
products to water treatment. Recent statistics regarding import for consumption indicate production
and use are robust (Table 3-1). Manganese and its compounds are also TRI chemicals (Tables 3-3
and 3-4). Industrial releases have occurred since 1988 in all 50 States. Off-site releases constitute a
considerable amount of total releases. Releases to land are the most significant on-site releases.
3.2 Ambient Occurrence
To understand the presence of a chemical in the environment, an examination of ambient
occurrence is useful. In a drinking water context, ambient water is source water existing in surface
waters and aquifers before treatment. The most comprehensive and nationally consistent data
describing ambient water quality in the United States are being produced through the United States
Geological Survey's (USGS) NAWQA program. (NAWQA, however, is a relatively young program
and complete national data are not yet available from their entire array of sites across the nation.)
3.2.1 Data Sources and Methods
The USGS instituted the NAWQA program in 1991 to examine water quality status and trends in
the United States. NAWQA is designed and implemented in such a manner as to allow consistency
and comparison between representative study basins located around the country, facilitating
interpretation of natural and anthropogenic factors affecting water quality (Leahy and Thompson,
1994).
The NAWQA program consists of 59 significant watersheds and aquifers referred to as "study
units." The study units represent approximately two thirds of the overall water usage in the United
States and a similar proportion of the population served by public water systems. Approximately one
half of the nation's land area is represented (Leahy and Thompson, 1994).
To facilitate management and make the program cost-effective, approximately one third of the
study units at a time engage in intensive assessment for a period of 3 to 5 years. This is followed by a
period of less intensive research and monitoring that lasts between 5 and 7 years. In this way, all 59
study units rotate through intensive assessment over a ten-year period (Leahy and Thompson, 1994).
The first round of intensive monitoring (1991-1996) targeted 20 study units, and the second round
monitored another 16, beginning in 1994.
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Regulatory Determination Support Document for Manganese July 2003
Manganese is an analyte for both surface and ground water NAWQA studies, with a Minimum
Reporting Level (MRL) of 0.001 mg/L. Manganese occurrence in bed sediments and aquatic biota
tissue is also assessed, with MRLs of 4 mg/kg and 0.1 mg/kg, respectively.
Manganese data from the first two rounds of intensive NAWQA monitoring have undergone USGS
quality assurance checks and are available to the public through their NAWQA Data Warehouse
(USGS, 2001). EPA has analyzed these data after further data quality review, and occurrence results
are presented below. The descriptive statistics generated from the manganese NAWQA data broadly
characterize the frequency of manganese detections by sample and by site. Furthermore, detection
frequencies above a HRL of 0.30 mg/L are also presented for all samples, and by site. The HRL is a
preliminary health effect level used for this analysis (see section 3.3.1.4 for further discussion of the
HRL and its development). The median and 99th percentile concentrations are included as well, to
characterize the spread of manganese concentration values in ambient waters sampled by the NAWQA
program.
3.2.2 Results
Typical of many inorganic contaminants, manganese occurrence in ambient surface and ground
waters is high (Table 3-5). This is not surprising, considering that manganese constitutes approximately
0.1% of the earth's crust (of the heavy metals, it is surpassed in abundance only by iron), and the
element and its compounds are used in many products. Significantly, manganese compounds are used
in wastewater and drinking water treatment.
Detection frequencies are consistently greater for surface water than for ground water, possibly
because surface waters are more sensitive to anthropogenic releases. Median concentrations are also
generally higher for surface water (median concentration for all sites is 0.016 mg/L in surface water and
0.005 mg/L in ground water). However, manganese detection frequencies greater than the HRL are
consistently higher in ground water, and 99th percentile ground water concentrations are as much as
eight times larger than corresponding 99th percentile surface water concentrations. Locally high
concentrations in ground water, higher than any seen in surface water, are not surprising given the
possibility of long contact times between ground water and rocks enriched in manganese. Contact
times between surface waters and naturally occurring manganese are orders of magnitude shorter,
hence concentrations are lower. Furthermore, surface waters subject to large anthropogenic inputs of
manganese are more easily diluted by waters integrated from other parts of the watershed, where
manganese concentrations may be lower.
Table 3-5 illustrates that low-level manganese occurrence is ubiquitous. Surface water detection
frequencies by site are greater than 95% for all land use categories. Median concentrations and HRL
exceedances (by site) are greater in urban and agricultural basins compared to basins characterized as
mixed land use or forest/rangeland. This distribution of manganese occurrence is probably influenced
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Regulatory Determination Support Document for Manganese July 2003
by the wide use of manganese compounds in both industry and agriculture. Mixed land use basins are
generally larger than either urban or agricultural basins, and the lower occurrence in these basins may
reflect some dilution of the contaminant. The 99th percentile concentrations for surface water range
from 0.4 mg/L-0.8 mg/L. The frequency of detections exceeding the MRL and HRL by site for all sites
are approximately 96.9% and 10.2%, respectively. These figures indicate that although manganese is
nearly ubiquitous in surface water, detections at levels of public health concern are relatively low.
For ground water, detections by site are higher in urban and forest/rangeland areas than in mixed or
agricultural lands. Over 80% of urban and forest/rangeland sites reported detections, while
approximately 63-64% of mixed and agricultural land use sites detected manganese. The finding that
ground water manganese occurrence is higher in forest/rangeland areas than in either mixed or
agricultural sites may result from natural variation in manganese occurrence in soil and rock. Urban
areas have the highest median and 99th percentile concentrations (0.015 mg/L and 5.6 mg/L,
respectively), as well as the highest detection frequencies (by site: 85.3%) and HRL exceedances (both
by sample [17.2%] and by site [21%]). These results suggest that urban releases of manganese and
manganese compounds can leach to ground water.
Detection frequencies and HRL exceedances by site for all ground water sites are approximately
70.1% and 13.8%, respectively. Again, these figures suggest that while manganese occurrence in
ground water is high, detections at levels of public health concern are modest.
Manganese was detected at 100% of NAWQA stream bed sediment sampling sites. The median
and 99th percentile concentrations in bed sediments are 1.1 mg/kg (dry weight) and 9.4 mg/kg (dry
weight), respectively. The occurrence of manganese in stream sediments is pertinent to drinking water
concerns because, though many manganese compounds are either insoluble or have low solubility and
are transported in water as suspended sediment, some desorption of the compound from sediments into
water will occur through equilibrium reactions, although at very low rates.
In aquatic biota tissue, detections are also 100% for all samples and sites (Table 3-6). However,
concentration percentiles for tissues are substantially lower than for bed sediments: the median for biotic
tissue is 0.01 mg/kg (dry weight) and the 99th percentile is 2.9 mg/kg (dry weight). Significant
manganese concentrations in aquatic biota tissues would imply a potential for bioaccumulation.
Although manganese was detected in aquatic biota tissues at 100% of samples and sites, low
concentration percentiles suggest that the element does not bioaccumulate appreciably.
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Regulatory Determination Support Document for Manganese July 2003
3.3 Drinking Water Occurrence
3.3.1 Analytical Approach
3.3.1.1 National Inorganic and Radionuclide Survey
In the mid-1980s, EPA designed and conducted the National Inorganic and Radionuclide Survey
(MRS) to collect national occurrence data on a select set of radionuclides and inorganic chemicals
being considered for National Primary Drinking Water Regulations. The MRS database includes 36
inorganic compounds (IOC) (including 10 regulated lOCs), 2 regulated radionuclides, and 4
unregulated radionuclides. Manganese was one of the 36 lOCs monitored.
The MRS provides contaminant occurrence data from 989 community PWSs served by ground
water. The MRS does not include surface water systems. The selection of this group of PWSs was
designed so that the contaminant occurrence results are statistically representative of national
occurrence. Most of the MRS data are from smaller systems (based on population served by the
PWS) and each of these statistically randomly selected PWSs was sampled a single time between 1984
and 1986.
The MRS data were collected from PWSs in 49 States (data were not available for Hawaii). In
addition to being statistically representative of national occurrence, MRS data are designed to be
divisible into strata, based on system size (population served by the PWS). Uniform detection limits
were employed, thus avoiding computational (statistical) problems that sometimes result from multiple
laboratory analytical detection limits. Therefore, the MRS data can be used directly for national
contaminant occurrence analyses with very few, if any, data quality, completeness, or
representativeness issues.
3.3.1.2 Supplemental IOC Data
One limitation of the MRS study is a lack of occurrence data for surface water systems. To
provide perspective on the occurrence of manganese in surface water PWSs relative to ground water
PWSs, SDWA compliance monitoring data that were available to EPA were reviewed from States
with occurrence data for both ground and surface water.
The State ground water and surface water PWS occurrence data for manganese used in this
analysis were submitted by States for an independent review of the occurrence of regulated
contaminants in PWSs at various times for different programs (USEPA, 1999). In the USEPA (1999)
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Regulatory Determination Support Document for Manganese
July 2003
Table 3-5: Manganese detections and concentrations in streams and ground water
Detection frequency
>MRL*
Detection frequency
>HRL*
Concentrations
(all samples; mg/L)
surface water
urban
mixed
agricultural
forest/rangeland
all sites
ground water
urban
mixed
agricultural
forest/rangeland
all sites
% samples
99.1 %
92.4 %
96.3 %
90.9 %
94.0 %
74.7 %
56.9 %
61.4%
75.3 %
64.1 %
% sites
99.6 %
98.5 %
97.2 %
96.4 %
96.9 %
85.3 %
62.9 %
64.0 %
81.3%
70.1%
% samples
4.6 %
1.3%
3.7 %
5.0 %
3.0 %
17.2 %
8.9 %
11.9%
10.9 %
12.8 %
% sites
13.0 %
6.4 %
12.3 %
6.6 %
10.2 %
21.0%
9.0 %
12.8 %
13.8 %
13.8 %
median
0.036
0.012
0.019
0.011
0.016
0.015
0.002
0.004
0.012
0.005
99th
perc entile
0.7
0.4
0.7
0.8
0.7
5.6
1.3
1.6
2.9
2.9
* The Minimum Reporting Level (MRL) for manganese in water is 0.001 mg/L and the Health Reference Level (HRL) is 0.30 mg/L.
The HRL is a preliminary health effect level used for this investigation.
Table 3-6: Manganese detections and concentrations in bed sediments and aquatic biota
tissues (all sites)
Detection frequency
>MRL*
Concentrations
(all samples; mg/kg dry weight)
sediments
aquatic biota tissues
% samples
100 %
100 %
% sites
100 %
100 %
median
1.1
0.01
gg'percentile
9.4
2.9
! The Minimum Reporting Levels (MRLs) for manganese in sediments and biota tissues are 4 ftg/g and 0.1 ftg/g, respectively.
16
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Regulatory Determination Support Document for Manganese July 2003
review, occurrence data from a total of 14 States were noted. However, because several States
contained data that were incomplete or unusable for various reasons, only 12 of the 14 States were
used for a general overview analysis. From these 12 States, 8 were selected for use in a national
analysis because they provided the best data quality and completeness and a balanced national cross-
section of occurrence data. These eight were Alabama, California, Illinois, Michigan, Montana, New
Jersey, New Mexico, and Oregon.
Only the Alabama, California, Illinois, New Jersey, and Oregon State data sets contained
occurrence data for manganese. The data represent more than 37,000 analytical results from about
4,000 PWSs, primarily collected from 1993 to 1997, though some earlier data are also included. The
number of sample results and PWSs vary by State.
3.3.1.3 Data Management
The data used in the State data analyses were limited to only those data with confirmed water
source and sampling type information. Only standard SDWA compliance samples were used; "special"
samples, or "investigation" samples (investigating a contaminant problem that would bias results), or
samples of unknown type were not used in the analyses. Various quality control and review checks
were made of the results, including follow-up questions to the States providing the data. Many of the
most intractable data quality problems encountered occurred with older data. These problematic data
were, in some cases, simply eliminated from the analysis. For example, when the number of
problematic data were insignificant relative to the total number of observations, they were dropped
from the analysis (for further details see USEPA, 1999).
3.3.1.4 Occurrence Analysis
The summary descriptive statistics presented in Table 3-7 for manganese are derived from analysis
of the MRS data. Included are the total number of samples, the percent samples with detections, the
99th percentile concentration of all samples, the 99th percentile concentration of samples with
detections, and the median concentration of samples with detections. The percentages of PWSs and
population served indicate the proportion of PWSs and PWS population served for which analytical
results showed a detection(s) of the contaminant (simple detection, > MRL) at any time during the
monitoring period; or a detection(s) greater than half the HRL; or a detection(s) greater than the URL.
The HRL used for this analysis is 0.30 mg/L.
The HRLs were derived for contaminants not considered to be "linear" carcinogens by the oral
route of exposure. EPA derived the HRL using a Reference Dose (RED) approach as follows: HRL =
(RfD x 70 kg)/2L x relative source contribution (RSC), where:
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Regulatory Determination Support Document for Manganese July 2003
RfD = an estimate of a daily oral exposure to the human population (including sensitive
subgroups) that is likely to be without an appreciable risk of deleterious effects during a lifetime.
It can be derived from a No Observed Adverse Effect Level (NOAEL), Lowest Observed
Adverse Effect Level (LOAEL), or benchmark dose, with uncertainty factors generally applied
to reflect limitations of the data used;
70 kg = The assumed body weight of an adult;
2L = The assumed daily water consumption of an adult;
RSC = The relative source contribution, or the level of exposure believed to result from
drinking water when compared to other sources (e.g., air), and is assumed to be 20% unless
noted otherwise.
EPA used only the best available peer reviewed data and analyses in evaluating adverse health
effects. Health effects information is available for manganese in the Integrated Risk Information System
(IRIS). IRIS is an electronic EPA database containing reviewed information (both inside and outside of
the Agency) on human health effects that may result from exposure to various chemicals in the
environment. These chemical files contain descriptive and quantitative information on RfDs for chronic
noncarcinogenic health effects and hazard identification; slope factors; and unit risks for carcinogenic
effects.
In Table 3-7, national occurrence is estimated by extrapolating the summary statistics for
manganese to national numbers for systems, and population served by systems, from the Water
Industry Baseline Handbook, Second Edition (USEPA, 2000e). From the handbook, the total
number of ground water community water systems (CWSs) plus ground water non-transient, non-
community water systems (NTNCWSs) is 59,440, and the total population served by ground water
CWSs plus ground water NTNCWSs is 85,681,696 persons (see Table 3-7). To arrive at the
national occurrence estimate for the HRL, the national estimate for ground water PWSs (or population
served by ground water PWSs) is simply multiplied by the percentage for the given summary statistic
[i.e., the national estimate for the total number of ground water PWSs with detections at the HRL of
0.30 mg/L (40,388) is the product of the percentage of ground water PWSs with detections (68%) and
the national estimate for the total number of ground water PWSs (59,440)].
The nationally extrapolated occurrence estimates for manganese are not presented in the Federal
Register Notice. While the MRS data were collected in a statistically appropriate fashion suitable for
extrapolation, the data available for many CCL regulatory determination priority contaminants were not
a strict statistical sample. National extrapolations of these data can be problematic. Also, the MRS
data only represent ground water PWSs. Thus, national extrapolations from MRS data do not
represent national occurrence for all PWSs. Therefore, to maintain consistency across all CCL
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Regulatory Determination Support Document for Manganese July 2003
regulatory determination priority contaminants, a straight-forward presentation, and data integrity, only
the actual occurrence results for all CCL regulatory determination priorities are presented in the
Federal Register Notice for stakeholder review. The nationally extrapolated occurrence values for
manganese are presented here, however, to provide additional perspective.
In Table 3-8, occurrence data on manganese directly submitted by the States of Alabama,
California, Illinois, New Jersey, and Oregon for^4 Review of Contaminant Occurrence in Public
Water Systems (USEPA, 1999) was used to augment the MRS study which lacked surface water
data. Included in the table are the same summary statistics as in Table 4-1, with additional information
describing the relative distribution of manganese occurrence between ground water and surface water
PWSs in the 5 States.
The State data analysis was focused on occurrence at the system level because a PWS with a
known contaminant problem usually has to sample more frequently than a PWS that has never detected
the contaminant. The results of a simple computation of the percentage of samples with detections (or
other statistics) can be skewed by the more frequent sampling results reported by the contaminated site.
The system level of analysis is conservative. For example, a system need only have a single sample
with an analytical result greater than the MRL, i.e., a detection, to be counted as a system with a result
"greater than the MRL."
When computing basic occurrence statistics, such as the number or percent of samples or systems
with detections of a given contaminant, the value (or concentration) of the MRL can have important
consequences. For example, the lower the reporting limit, the greater the number of detections (Ryker
and Williamson, 1999). As a simplifying assumption, a value of half the MRL is often used as an
estimate of the concentration of a contaminant in samples/systems whose results are less than the MRL.
However, for these occurrence data this is not straightforward. This is in part related to State data
management differences as well as real differences in analytical methods, laboratories, and other
factors.
The situation can cause confusion when examining descriptive statistics for occurrence. Because a
simple meaningful summary statistic is not available to describe the various reported MRLs, and to
avoid confusion, MRLs are not reported in the summary table (Table 3-8).
3.3.1.5 Additional Drinking Water Data from 1996 AWWA Survey
To augment the SDWA drinking water data analysis described above, results from a 1996
American Water Works Association (AWWA) survey are reviewed. The survey, called WaterStats, is
a cooperative project of AWWA and AWWA Research Foundation. The WaterStats survey
database stores results from the 1996 WaterStats survey of water utilities in the United States and
Canada in terms of facilities, scale of operation, and major inputs and outputs. A total of 794 AWWA
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Regulatory Determination Support Document for Manganese July 2003
member utilities responded to the survey with ground water and/or surface water information.
However, the actual number of respondents for each data category varies because not all participants in
the survey responded to every question.
3.3.2 Results
The MRS data in Table 3-7 show that approximately 68% of ground water PWSs (an estimate of
approximately 40,000 systems nationally) had detections of manganese, affecting about 55% of the
ground water PWS population served (approximately 47.5 million people nationally). At an HRL of
0.30 mg/L, approximately 6.1% of the MRS PWSs had detections greater than half the HRL (about
3,600 ground water PWSs nationally), affecting approximately 4.6% of the population served
(estimated at 3.9 million people nationally). The percentage of MRS PWSs with detections greater
than the HRL of 0.30 mg/L was approximately 3.2% (about 1,900 ground water PWSs nationally),
affecting 2.6% of the population served (estimated at approximately 2.3 million people nationally)
(Table 3-7).
Drinking water data for manganese from the supplemental individual States vary among States
(Table 3-8). Manganese has not been required for monitoring under the SDWA, though these States
had obviously conducted some monitoring. The number of systems with manganese data for Illinois
and Oregon is far less than the number of PWSs in these States. Hence, it is not clear how
representative these data are. Alabama, California, and New Jersey have substantial amounts of data
and PWSs represented. Because the MRS data only represent manganese occurrence in ground
water PWSs, the supplemental State data sets provide some perspective on surface water PWS
occurrence. For example, the median concentration of detections for the States ranged from 0.02
mg/L to 0.15 mg/L, higher than the MRS data (0.01 mg/L). For detections by PWSs, 3 of the 5
States (California, Illinois, and Oregon) had higher ground water PWS detections.
For simple detections, the supplemental State data show a range from 30% to 56% of ground
water PWSs (Table 3-8). These figures are lower than the MRS ground water PWS results: 68%
greater than the MRL (Table 3-7). The supplemental State data show considerably greater
percentages of simple detections for surface water PWSs, with higher variability as well: 12% - 97%
greater than the MRL. Comparisons made between data for simple detections need to be viewed with
caution because of differences in MRLs between the State data sets and the MRS study, and among
the States themselves (see section 3.3.1.4).
The supplemental State data sets indicate ground water PWS detections greater than the HRL of
0.30 mg/L between 0.6% and 11% (Table 3-8). Again, this range brackets the MRS national average
of PWS above the HRL of 0.30 mg/L (3.2%) (Table 3-8). Notably, surface water PWSs showed
fewer exceedances of the HRL than ground water PWSs at this higher concentration; ranging from 0%
to 3.1%.
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Regulatory Determination Support Document for Manganese July 2003
Reviewing manganese occurrence by PWS population served shows that from 0.1% - 43% of the
States' ground water PWS populations were served by systems with detections greater than the HRL
of 0.30 mg/L (Table 3-8). Comparatively, 2.6% of the MRS ground water PWS population served
experienced detections greater than the HRL of 0.30 mg/L (Table 3-7). Populations served by surface
water PWSs with detections greater than the HRL of 0.30 mg/L ranged from 0% - 14.5% among the
five supplemental States. Population figures for the supplemental States are incomplete and are only
reported for those systems in the database that have reported their population data. For manganese,
approximately 80% of the PWSs reporting occurrence data for these 5 States also reported population
data.
3.3.2.1 Occurrence in AWWA PWSs
The AWWA sponsored 1996 WaterStats Survey showed manganese occurrence above levels of
health concern to be generally similar to those reported in the MRS data and the supplemental State
data. In finished ground water samples, approximately 3% of survey respondents (serving close to 1.6
million people) had maximum detections of manganese greater than the HRL of 0.30 mg/L. The 99th
percentile concentration and the median concentration were 0.80 mg/L and 0.021 mg/L, respectively.
For finished surface water samples, approximately 1.5% of survey respondents (serving about 1.7
million people) reported maximum detections greater than the HRL of 0.30 mg/L. The 99th percentile
concentration and the median concentration in finished surface water samples were 0.64 mg/L and
0.013 mg/L, respectively.
Approximately 11% of the participating ground water PWSs (serving about 5.1 million people) had
maximum detections of manganese in raw water greater than the HRL of 0.30 mg/L. The 99th
percentile of concentration and the median concentration were 9.0 mg/L and 0.09 mg/L, respectively.
Surface water PWSs showed comparable results, with approximately 12.8% of survey respondents
(serving about to 10.5 million people) having maximum detections of manganese in raw water greater
than the HRL of 0.30 mg/L. The 99th percentile of concentration and the median concentration in raw
surface waters were 3.08 mg/L and 0.092 mg/L, respectively.
3.4 Conclusion
Manganese and its compounds are TRI chemicals. Industrial releases have been reported since
1988 in all 50 States. Off-site releases constitute a considerable amount of total releases, with releases
to land the most significant on-site releases.
Low-level manganese occurrence in ambient waters and bed sediments monitored by the USGS
NAWQA program is ubiquitous, with detections approaching 100% of surface water sites and greater
than 62% of ground water sites. Stream bed sediments and aquatic biota tissues show detections of
100% by sample and by site. Urban basins generally have more surface and ground water manganese
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Regulatory Determination Support Document for Manganese
July 2003
Table 3-7: Manganese occurrence in ground water systems (NIRS survey)
Frequency Factors
Total Number of Samples/Systems
99th Percentile Concentration (all samples)
Minimum Reporting Level (MRL)
99th Percentile Concentration of Detections
Median Concentration of Detections
Total Population
Occurrence by Sample/System
% Ground Water PWSs with detections (> MRL)
Range of Sampled States
% Ground Water PWSs > 1/2 Health Reference Level (HRL)
Range of Sampled States
% Ground Water PWSs > HRL
Range of Sampled States
Occurrence by Population Served
% Ground Water PWS Population Served with detections
Range of Sampled States
% Ground Water PWS Population Served > 1/2 HRL
Range of Sampled States
% Ground Water PWS Population Served > HRL
Range of Sampled States
Health Reference
Level = 0.30 mg/L
989
0.63 mg/L
0.001 mg/L
0.72 mg/L
0.01 mg/L
1,482,133
67.9%
8.3 - 100%
6.1%
0-31.6%
3.2%
0 - 21.0%
55.4%
0.3 - 100%
4.6%
0 - 89.2%
2.6%
0 - 89.2%
National System &
Population Numbers1
59,440
-
-
-
-
85,681,696
National Extraoolation
HRL = 0.30
40,388
N/A
3,606
N/A
1,923
N/A
47,502,000
N/A
3,940,000
N/A
2,256,000
N/A
1 Total PWS and population numbers are from EPA March 2000 Water Industry Baseline Handbook.
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Regulatory Determination Support Document for Manganese
July 2003
Table 3-8: Occurrence summary of ground and surface water systems, by State, for
Frequency Factors
Total Number of Samples
Number of Ground Water Samples
Number of Surface Water Samples
Percent of Samples with Detections
Percent of Ground Water Samples with Detections
Percent of Surface Water Samples with Detections
99 Percentile Concentration (all samples)
Minimum Reporting Level (MRL)
99th Percentile Concentration of Detections
Median Concentration of Detections
Total Number of PWSs
Number of Ground Water PWSs
Number of Surface Water PWSs
Total Population Served
Ground Water Population
Surface Water Population
Occurrence by System
% PWSs with detections (> MRL)
Ground Water PWSs with detections
Surface Water PWSs with detections
Health Reference Level (HRL) = 0.03 mg/L
% PWSs > 1/2 HRL
Ground Water PWSs > 1/2 HRL
Surface Water PWSs > 1/2 HRL
% PWSs > HRL
Ground Water PWSs > HRL
Surface Water PWSs > HRL
Occurrence by Population Served
% PWS Population Served with detections
Ground Water PWS Population with detections
Surface Water PWS Population with detections
Health Reference Level (HRL) = 0.03 mg/L
% PWS Population Served > 1/2 HRL
Ground Water PWS Population > 1/2 HRL
Surface Water PWS Population > 1/2 HRL
% PWS Population Served > HRL
Ground Water PWS Population > HRL
Surface Water PWS Population > HRL
Alabama
1,343
934
409
30.2%
28.1%
35.0%
0.13 mg/L
Variable
0.56 mg/L
0.02 mg/L
434
365
69
3,662,222
1,820,214
1,837,743
46.5%
41.6%
72.5%
1.8%
1.4%
4.4%
0.9%
0.6%
2.9%
71.9%
50.9%
73.4%
5.9%
0.8%
0.7%
2.4%
0.1%
0.6%
California
31,998
29,923
2,075
16.5%
17.5%
1.9%
0.71 mg/L
Variable
1.52 mg/L
0.15 mg/L
2,516
2,293
223
45,388,246
27,840,774
30,675,992
28.2%
29.8%
11.7%
17.2%
18.5%
3.6%
10.1%
10.9%
1.8%
49.3%
66.2%
10.5%
34.8%
52.6%
4.4%
27.2%
42.8%
4.2%
Illinois
344
275
69
44.2%
50.2%
20.3%
0.96 mg/L
Variable
57 mg/L
0.04 mg/L
227
160
67
1,995,394
724,635
1,270,179
41.4%
50.6%
19.4%
9.3%
11.9%
3.0%
4.4%
5.0%
3.0%
36.5%
66.3%
19.5%
16.5%
29.1%
9.4%
14.7%
24.2%
9.4%
New Jersey
3,196
2,795
401
39.7%
40.6%
33.7%
0.42 mg/L
Variable
0.89 mg/L
0.02 mg/L
1,179
1,147
32
7,472,565
2,386,396
3,687,076
53.5%
52.3%
96.9%
5.8%
5.7%
9.4%
2.5%
2.5%
3.1%
85.7%
70.4%
100.0%
15.3%
10.4%
23.3%
9.1%
4.9%
14.5%
Oregon
172
90
82
39.5%
61.1%
15.9%
1.6 mg/L
Variable
6.7 mg/L
0.05 mg/L
84
54
30
1,306,283
301,440
1,117,782
46.4%
55.6%
30.0%
13.1%
20.4%
0.0%
6.0%
9.3%
0.0%
58.0%
41.8%
56.8%
4.6%
19.9%
0.0%
3.2%
14.0%
0.0%
manganese
1 See section 3.3.1.4 for details
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Regulatory Determination Support Document for Manganese July 2003
detections greater than the HRL than basins in other land use categories do, and higher median and 99th
percentile concentrations. Although manganese detection frequencies are high in ambient waters,
stream bed sediments, and aquatic biota tissue, manganese occurrence at levels of public health
concern is low.
Manganese has been detected in ground water PWS samples collected through the MRS study.
Occurrence estimates are relatively high, with approximately 68% of all samples showing detections
affecting about 55% of the national population served. The 99th percentile concentration of all samples
is 0.63 mg/L. Exceedances of the HRL at 0.30 mg/L affect approximately 2.3 million people nationally.
Additional SDWA compliance data from the States of Alabama, California, Illinois, New Jersey,
and Oregon, including both ground water and surface water PWSs, were examined through
independent analyses and also show substantial levels of manganese occurrence. These data provide
perspective on the MRS estimates that only include data for ground water systems. The supplemental
State data show ground water systems reported higher manganese detections in 3 of the 5 States
(California, Illinois, and Oregon). If national data for surface water systems were available, the
occurrence and exposure estimates would be substantially greater than from MRS alone.
4.0 HEALTH EFFECTS
A description of the health effects and dose-response information associated with exposure to
manganese is summarized below. For additional detail, please refer to the Health Effects Support
Document for Manganese (USEPA, 2003b).
4.1 Hazard Characterization and Mode of Action Implications
The primary route of exposure to toxic levels of manganese is through the inhalation of manganese
dust. Oral exposure to levels of lexicological concern is less common. The major adverse health effect
of manganese exposure is neurotoxicity, which is characterized at high doses by ataxia (i.e.,
coordination impairment), increased anxiety, dementia, a "mask-like" face, involuntary movements, or a
syndrome similar to Parkinson's disease. While the precise mechanisms of manganese neurotoxicity
are not known, the observed effects of manganese on the globus pallidus region of the brain suggest
that a likely mechanism involves impairment of the neurotransmitter dopamine, which is involved in
coordination of movement.
While manganese is potentially harmful at high concentration levels, it is also an essential nutrient in
developing infants. For this reason, the adverse effects from manganese deficiency may, at times, be of
greater concern than potential toxicity from over-exposure. An added complication is the fact that
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Regulatory Determination Support Document for Manganese July 2003
many inhibitors of manganese absorption, such as phytates and plant fiber, are commonly found in infant
diets, thus lowering the actual absorption of ingested manganese. Absorption of the mineral from
manganese-rich foods may also be inhibited by the presence of co-occurring plant proteins that bind
manganese and decrease its bioavailability. For example, although the manganese content in a soy-
based formula is higher than the manganese content in human milk, the actual absorption of manganese
from the formula may not be substantially greater, since soy milk is high in phytate and vegetable
protein. Human and cow milk contain different proteins that also bind manganese, but in some cases,
the presence of these proteins actually enhances manganese transport across the gut wall, increasing
absorption.
Other instances in which high dietary levels of manganese may not necessarily correspond to high
dose levels include vegetarian diets and tea drinkers. Many vegetables contain high manganese levels
but have high fiber and phytate levels. Likewise, tea contains high manganese levels, but the
accompaniment of tannin, another inhibitor of manganese absorption, decreases the absorption of
manganese.
Several studies have explored the intake level of manganese at which it may be considered safe in
humans. Although the Estimated Safe and Adequate Daily Dietary Intake (ESADDI) for manganese
has been established at 2-5 mg/day for adults (NRC, 1989), Davis and Greger (1992) have found that
a daily intake of 15 mg/day for 90 days results in no adverse effects in women; the only effect seen was
an increase in superoxide dismutase activity. In 2001, the Institute of Medicine (IOM) undertook a
review of Dietary Reference Intakes for a number of substances. An adequate intake level for
manganese was set at 2.3 mg/day for men and 1.8 mg/day for women (IOM, 2001). The IOM report
also sets a tolerable upper intake level of 11 mg/day for adults, based on a review by Greger (1999). It
suggested that people eating Western type and vegetarian diets may have intakes as high as 10.9
mg/day.
4.2 Dose-Response Characterization and Implications in Risk Assessment
The dose-response relationship for neurological effects of manganese by ingestion is not well-
characterized in animals or humans. Epidemiological data for humans indicate that intakes as high as 11
mg/day (0.16 mg/kg-day) may not cause any adverse effects in adult humans. Additional evidence,
based on a study where women received daily supplements of 15 mg manganese for 90 days, suggests
a safe level as high as 15 mg/day (Davis and Greger, 1992).
A review of acute animal toxicity studies indicates that manganese has a low to moderate oral
toxicity. For example, the oral dose of manganese compounds at which 50% of rats died is in the
range of 400-2,000 mg/kg. While some animal studies have also reported developmental and
reproductive effects at high doses for certain manganese compounds, most data from oral exposure
suggest that manganese has a low developmental toxicity.
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Regulatory Determination Support Document for Manganese July 2003
EPA has calculated a RED, or an estimate of a daily exposure via ingestion to the human population
that is likely to be safe, for manganese. The RfD for manganese in food is 0.14 mg/kg-day, based on
dietary surveys which have reported daily manganese intake of 10 mg in average 70 kg adults without
adverse effects. As a precautionary measure for drinking water, EPA recommends applying a
modifying factor (MF) of 3 to yield a value of 0.047 mg/kg-day. One concern addressed by this MF is
the potential for humans to absorb greater levels of manganese by drinking water during early morning,
when the gut is empty, than by exposure in food.
There is no information available regarding the carcinogenicity of manganese in humans; animal
studies have reported mixed results. The USEPA classified manganese as Group D, or not classifiable
as to human carcinogenicity. The Reference Concentration (RfC), an estimate of daily exposure via
inhalation that is likely to be safe, for manganese is 5 x 10"5 mg/m3 (USEPA, 1998c). The RfC was
derived using data from two epidemiological studies of workers exposed to manganese dioxide dust in
an occupational setting (Roels et al., 1987; Roels et al, 1992).
4.3 Relative Source Contribution
Relative source contribution analysis compares the magnitude of exposures expected via
consumption of drinking water with those estimated for other relevant media such as food, air, and soil.
Occurrence data for manganese provides the basis for estimating the amounts of manganese ingested
via drinking water in the exposed population. According to the MRS data, the median and 99th
percentile concentrations for manganese in ground water public water supplies are above the MRL of
0.001 mg/L. This is not surprising considering the ubiquity of manganese in the earth's crust.
Taking the median concentration of detections from the MRS data (0.01 mg/L), and assuming a
daily intake of 2 L of drinking water by a 70 kg adult, the average daily dose would be 2.8 x io~4
mg/kg-day. The corresponding dose for a 10 kg child consuming 1 L/day of drinking water would be
1.0 x 10"3 mg/kg-day. These values are lower than the levels that the IOM (2001) considers to be safe
and adequate. The IOM has determined that a daily intake of 2.3 mg manganese for men and 1.8 mg
for women is adequate, while the daily adult intake expected from drinking water is 0.02 mg
manganese. The IOM also determined that a daily intake of 1.9 mg manganese is adequate for boys
and 1.6 mg is adequate for girls, while the daily intake expected from drinking water is 0.01 mg for
children (IOM, 2001). The National Research Council proposed even higher recommended intakes of
manganese: their ESADDI for manganese is 2-5 mg for adults (MIC, 1989).
4.4 Sensitive Populations
Potentially sensitive sub-populations include the elderly, pregnant women, iron-deficient individuals,
and individuals with impaired liver function. Because excretion by the liver is the primary route of
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Regulatory Determination Support Document for Manganese July 2003
manganese elimination, individuals with impaired liver function may be especially susceptible to
manganese toxicity (Layrargues et al., 1998). Infants and neonates, whose capacity for excretion
through the bile is not fully developed, may also be potentially susceptible to manganese toxicity
(Fechter, 1999). Although animal studies have indicated an increased potential in neonates for
gastrointestinal absorption of manganese, as well as decreased excretion potential, the degree to which
these findings apply to human infants is unknown. There are no data to indicate that children are more
sensitive to manganese than adults. Those who are iron deficient may also experience greater
susceptibility to manganese absorption and toxicity (Finley, 1999; Finley et al., 1994).
4.5 Exposure and Risk Information
Estimates of exposed populations were described in the occurrence section of this document.
National population estimates for manganese exposure were derived using summary statistics from the
MRS, in addition to supplemental surface water occurrence data, that was separately submitted to
EPA from five States.
Based on available data, approximately 47.5 million people are served by ground water public
water systems with detections above the MRL. Furthermore, an estimated 4.0 million people (4.6% of
the population) are served by ground water with levels above one-half the FIRL of 0.30 mg/L. In
addition, an estimated 2.3 million people (2.6% of the population) are served by ground water with
levels above the URL.
Considering that manganese is an essential nutrient which is commonly found in normal diets, the
estimated daily exposure to manganese from public water systems is far below the expected daily
intake from diet. When average daily intakes from drinking water are compared with intakes from
food, air and soil, drinking water accounts for a relatively small proportion of manganese intake. On
the basis of these observations, the impact of regulating manganese concentrations in drinking water on
health risk reduction is likely to be small.
4.6 Conclusion
While there is evidence that manganese may have adverse health effects in humans at high doses
through inhalation, studies indicate that oral ingestion at levels commonly found in western diets have no
noticeable adverse effects. In addition, because manganese is an essential nutrient, concern over
potential toxic effects from high oral exposure must be balanced against concern for adverse effects
from manganese deficiency. Through a special study of contaminant occurrence in ground water
systems (MRS), it is estimated that manganese occurs at levels above the URL (0.30 mg/L) in
approximately 1,900 ground water systems nationwide (about 3.2% of the nation's ground water
PWSs), affecting approximately 2.3 million people nationwide (2.6 % of the U.S. PWS population-
served). However, the URL concentration is far less than the average daily intake of manganese
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Regulatory Determination Support Document for Manganese July 2003
through non-water sources. It is therefore unlikely that manganese in drinking water will occur at
concentrations that are of public health concern or that regulation represents a meaningful opportunity
for health risk reduction in persons served by public water systems. All CCL regulatory determinations
and further analysis are formally presented in the Federal Register Notices (USEPA, 2002; 67 FR
38222, and USEPA, 2003a; 68 FR 42898).
5.0 TECHNOLOGY ASSESSMENT
If a determination has been made to regulate a contaminant, SDWA requires development of
proposed regulations within 2 years of making the decision. It is critical to have suitable monitoring
methods and treatment technologies to support regulation development.
5.1 Analytical Methods
The availability of analytical methods does not influence EPA's determination of whether or not a
CCL contaminant should be regulated. However, before EPA actually regulates a contaminant and
establishes a Maximum Contaminant Level (MCL), there must be an analytical method suitable for
routine monitoring. Therefore, EPA needs to have approved methods available for any CCL regulatory
determination contaminant before it is regulated with an NPDWR. These methods must be suitable for
compliance monitoring and should be cost effective, rapid, and easy to use. Manganese can be
measured by several well-documented analytical methods (see Table 5-1).
5.2 Treatment Technology
Treatment technologies also do not influence the determination of whether or not a contaminant
should be regulated. But, before a contaminant can be regulated with an NPDWR, treatment
technologies must be readily available. Manganese is one of three inorganic contaminants listed as
Regulatory Determination Priorities on the CCL. The treatment data for these inorganic compounds
was obtained from EPA's technology and cost documents, the Office of Research and Development's
(ORD) National Risk Management Research Laboratory (NRMRL) Treatability Database, and
published studies. The technologies reviewed include conventional treatment, ion exchange, reverse
osmosis, lime softening, and chemical precipitation.
Conventional treatment usually includes pre-treatment steps of chemical coagulation, rapid mixing,
and flocculation, followed by floe removal via sedimentation or flotation. After clarification, the water is
then filtered. Common filter media include sand, and dual- and tri-media (e.g., silica sand, garnet sand,
or anthracitic coal).
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Regulatory Determination Support Document for Manganese
July 2003
Table 5-1: Analytical Methods for Manganese
Method
/
EPA 200.7
SMS 120 B
EPA 200.8
SM3111B
EPA 200.9
SM3113B
Type
Inductively Coupled
Plasma Optical
Emission Spectrometry
(ICP)/Atomic Emission
Spectrometry
TCP/ Atomic Emission
Spectrometry
TCP/Mass
Spectrometry
Atomic Absorption,
direct aspiration
Stabilized Temperature
Graphite Furnace AA
Spectrometry
Atomic Absorption,
Furnace
Method Detection
I^iitdngff,)
1.0
Estimated Detection
Limit (EDL) 2.0
0.02
Instrument Detection
Level (IDL) 10 Optimum
cone, range 100-10,000
0.3
EDL 0.2 Optimum cone.
range 1-30
Ion exchange involves the selective removal of charged inorganic species from water using an ion-
specific resin. The surface of the ion exchange resin contains charged functional groups that hold ionic
species by electrostatic attraction. As water containing contaminant ions passes through a column of
resin beds, charged ions on the resin surface are exchanged for the contaminant species in the water.
Reverse osmosis (RO) is similar to other membrane processes, such as ultrafiltration and
nanofiltration, since water passes through a semi-permeable membrane. However, in the case of RO,
the principle involved is not filtration. Instead, it involves the use of applied hydraulic pressure to
oppose the osmotic pressure across a non-porous membrane, forcing the water from the concentrated
solution side to the dilute solution side. The water does not travel through pores, but rather dissolves
into the membrane, diffuses across, then dissolves out into the permeate. Most inorganic and many
organic contaminants are rejected by the membrane and will be retained in the concentrate.
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Regulatory Determination Support Document for Manganese July 2003
In the lime-softening process, the pH of the water being treated is raised sufficiently to precipitate
calcium carbonate and, if necessary, magnesium hydroxide. Calcium and magnesium ions in water
cause hardness. After mixing, flocculation, sedimentation, and pH readjustment, the softened water is
filtered.
Results of a preliminary technology assessment and review indicate that all of the above-mentioned
techniques remove manganese from water. However, data indicate that chemical precipitation is the
most effective option.
6.0 SUMMARY AND CONCLUSIONS - DETERMINATION OUTCOME
Three statutory criteria are used to guide the determination of whether regulation of a CCL
contaminant is warranted: 1) the contaminant may adversely affect the health of persons; 2) the
contaminant is known or is likely to occur in public water systems with a frequency, and at levels, of
public health concern; and 3) regulation of the contaminant presents a meaningful opportunity for health
risk reduction for persons served by public water systems. As required by SDWA, a decision to
regulate a contaminant commits the EPA to proposal of a Maximum Contaminant Level Goal (MCLG)
and promulgation of a NPDWR for the contaminant. A decision not to regulate a contaminant is
considered a final Agency action and is subject to judicial review. The Agency can choose to publish a
Health Advisory (a nonregulatory action) or other guidance for any contaminant on the CCL that does
not meet the criteria for regulation.
There is evidence that manganese may have adverse health effects in humans at high doses through
inhalation, most importantly as a neurotoxin (producing ataxia, anxiety, dementia, a "mask-like" face,
involuntary movements, or a syndrome similar to Parkinson's disease). Nevertheless, oral exposure at
levels common in Western diets is not known to produce adverse health effects. In addition, because
manganese is an essential nutrient, concern over potential toxic effects from high oral exposure must be
balanced against concern for adverse effects from manganese deficiency. Potentially sensitive
subpopulations include the elderly, pregnant women, iron-deficient individuals, and individuals with
impaired liver function. Manganese is not a known carcinogen.
Manganese is a naturally occurring element that constitutes approximately 0.1% of the earth's crust.
Industrially, manganese compounds are produced in the United States from manganese ore and are in
widespread use in the steel, fertilizer and water treatment industries. Releases have been reported since
1988 in all 50 States. Monitoring data indicate that low-level manganese occurrence in ambient waters
and bed sediments monitored by the USGS NAWQA program is ubiquitous, with detections
approaching 100% of surface water sites and greater than 62% of ground water sites. Stream bed
sediments and aquatic biota tissues show detections of 100% by sample and by site. Although
30
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Regulatory Determination Support Document for Manganese July 2003
manganese detection frequencies are high in ambient waters, stream bed sediments, and aquatic biota
tissue, manganese occurrence at levels of public health concern is low.
Manganese has been detected in ground water public water system (PWS) samples collected
through the MRS study. Occurrence estimates are relatively high with approximately 68% of all
sampled PWSs showing detections, indicating that manganese is present in PWSs that serve about
55% of the national population. Exceedances of the HRL of 0.30 mg/L affect 2.6% of the population,
or approximately 2.3 million people nationally. The 99th percentile concentration of all samples is 0.63
mg/L. Additional SDWA compliance data from the States of Alabama, California, Illinois, New
Jersey, and Oregon, including both ground water and surface water PWSs, were examined through
independent analyses and also show substantial levels of manganese occurrence.
The levels of manganese frequently detected in PWSs are far below the average daily intake of
manganese through non-water sources: for example, the median concentration of detects in the MRS
survey is 0.01 mg/L, while studies have indicated that for a 70 kg adult, a daily manganese intake of 10
mg through diet presents no adverse effect.
Because manganese ingestion is not known to present adverse health effects at low levels, and
because drinking water contributes only a small portion of normal oral intake, it is unlikely that
regulation of manganese in drinking water would represent a meaningful opportunity for health risk
reduction in persons served by public water systems. All CCL regulatory determinations and further
analysis are formally presented in the Federal Register Notices (USEPA, 2002; 67 FR 38222, and
USEPA, 2003a; 68 FR 42898).
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REFERENCES
Agency for Toxic Substances and Disease Registry (ATSDR). 1997. Toxicological Profile for
Manganese (Update). Draft for public comment. Atlanta: Agency for Toxic Substances and
Disease Registry. 201pp.
ATSDR. 2000. Toxicological Profile for Manganese (Update). Draft for public comment.
Atlanta: Agency for Toxic Substances and Disease Registry.
Davis, C.D. and J.L. Greger. 1992. Longitudinal Changes of Manganese-Dependent Superoxide
Dismutase and Other Indexes of Manganese and Iron Status in Women. Am. J. Clin. Nutr.
55(3):747-752 (as cited in ATSDR, 2000).
Drever, James I. 1988. The Geochemistry of Natural Waters. Second Edition. Englewood Cliffs,
NJ: Prentice Hall. 437 pp.
Fechter, L.D. 1999. Distribution of Manganese in Development. Neurotoxicology. 20:197-201.
Finley, J.W. 1999. Manganese Absorption and Retention by Young Women is Associated with
Serum Ferritin Concentration. Am. J. Clin. Nutr. 70:37-43.
Finley, J.W., P.E. Johnson and L.K. Johnson. 1994. Sex Affects Manganese Absorption and
Retention by Humans From a Diet Adequate in Manganese. Am. J. Clin. Nutr. 60(6):949-955.
Greger, J.L. 1999. Nutrition Versus Toxicology of Manganese in Humans: Evaluation of Potential
Biomarkers. Neurotoxicology. 20:205-212.
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Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon,
Vanadium and Zinc: A Report of the Panel on Micronutrients, Subcommittees on Upper
Reference Levels of Nutrients and of Interpretation and Use of Dietary Reference Intakes,
and the Standing Committee on the Scientific Evaluation of Dietary Reference Intakes, Food
and Nutrition Board, Institute of Medicine. Washington, DC: National Academy Press
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Accessed January 25, 2001.
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Leahy, P.P., and T.H. Thompson. 1994. The National Water-Quality Assessment Program. US
Geological Survey Open-File Report 94-70. 4 pp. Available on the Internet at:
http://water.usgs.gov/nawqa/NAWQA.OFR94-70.html Last updated August 23, 2000.
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D.C.: National Academy Press. 302 pp.
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Manganese in Workers Exposed to Manganese Dioxide Dust. Br. J. Ind. Med. 49(l):25-34 (as
cited in USEPA, 1999).
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APPENDIX A: Abbreviations and Acronyms
ATSDR - Agency for Toxic Substances and Disease Registry
AWWA - American Water Works Association
CAS - Chemical Abstract Service
CCL - Contaminant Candidate List
CEC - cation exchange capacity
CERCLA - Comprehensive Environmental Response, Compensation & Liability Act
CWS - Community Water System
Eh - oxidation-reduction potential
EPA - Environmental Protection Agency
EPCRA - Emergency Planning and Community Right-to-Know Act
ESADDI - estimated safe and adequate daily dietary intake
FR - Federal Register
g/mol - grams per mole
HRL - Health Reference Level
IOC - inorganic compound
IOM - Institute of Medicine
IRIS - Integrated Risk Information System
Koc - organic carbon partition coefficient
Kow - octanol-water partitioning coefficient
L - liter
LOAEL - lowest observed adverse effect level
MCL - maximum contaminant level
MCLG - maximum contaminant level goal
MF - modifying factor
mg - milligram
mg/kg-day - milligram per kilogram per day
mm Hg - millimeter mercury
MMT - methylcyclopentadienyl manganese tricarbonyl
MRL - Minimum Reporting Level
NAWQA - National Water Quality Assessment Program
NDWAC - National Drinking Water Advisory Council
MRS - National Inorganic and Radionuclide Survey
nm - nanometer
NOAEL - no observed adverse effect level
NPDES - National Pollution Discharge Elimination System
NPDWR - National Primary Drinking Water Regulation
NRC - National Research Council
NRMRL - National Risk Management Research Laboratory
NTNCWS - Non-Transient Non-Community Water System
OGWDW - Office of Ground Water and Drinking Water
ORD - Office of Research and Development
OSHA - Occupational Safety and Health Administration
PEL - permissible exposure limit
pH - the negative log of the concentration of H+ ions
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ppm
PWS
RfC
RfD
RO
RSC
SARA
SDWA
SMCL
TRI
UCM
UCMR
USEPA
USGS
Mg
>MCL
>MRL
part per million
Public Water System
reference concentration
reference dose
reverse osmosis
relative source contribution
Superfund Amendments and Reauthorization Act
Safe Drinking Water Act
Secondary Maximum Contaminant Level
Toxic Release Inventory
Unregulated Contaminant Monitoring
Unregulated Contaminant Monitoring Regulation/Rule
United States Environmental Protection Agency
United States Geological Survey
micrograms
percentage of systems with exceedances
percentage of systems with detections
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