United States Office of Water EPA 815-R-99-007
Environmental Protection (4606) March 2000
Agency Washington, DC
4»EPA Technical Background
Information for the
Unregulated Contaminant
Monitoring Regulation
^Printed on Recycled Paper
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Foreword
Under the Safe Drinking Water Act (SDWA), as amended in 1996, §1445(a)(2)(A), the Environ-
mental Protection Agency (EPA) was to promulgate regulations for a monitoring program for unregulated
contaminants by August 1999. In the past, unregulated contaminant monitoring has been performed
according to the program described in CFR 141.40. The 1996 SDWA Amendments direct a substantially
revised Unregulated Contaminant Monitoring Regulation (UCMR). The revised UCMR (64 FR 50555)
has a new list of contaminants and makes other changes in the number of public water systems (PWSs)
that must conduct monitoring and in the frequency and schedule for monitoring. Additional regulatory
actions also include cancellation of unregulated contaminant monitoring for small systems serving 10,000
or fewer persons under the existing unregulated contaminant monitoring program begun in 1989. The data
collected under the UCMR will be used to support the development of the Contaminant Candidate List
(CCL), to support the Administrator's determination of whether to regulate a contaminant, and to develop
regulations. The revised monitoring program is one of the cornerstones of the sound science approach to
future drinking water regulation that is an aim of the 1996 SDWA Amendments. This document provides
technical background information on the process used to select contaminants for the revised UCMR, the
analytical methods that have been evaluated for use in the revised monitoring program, the spatial distri-
bution of use, environmental release, and production of the UCMR contaminants, and the rationale for the
timing and location of monitoring for these contaminants.
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Disclaimer
This document is designed to provide technical background information for the Unregulated
Contaminant Monitoring Regulation, as published in the Federal Register on September 17, 1999. (64 FR
50555). The document does not, however, substitute for the SDWA or EPA's regulations nor is this
document a regulation itself. 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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Acknowledgments
This document was prepared in support of the Unregulated Contaminant Monitoring Regulation
(UCMR) for EPA's Office of Ground Water and Drinking Water. Charles Job served as EPA's team leader
for development of the UCMR and James Taft as Targeting and Analysis Branch Chief. Rachel Sakata
and Yvette Selby served as Work Assignment Managers. The UCMR Work Group provided technical
guidance throughout. Evelyn Washington, James Sinclair, and David Munch provided technical and
editorial guidance. The Cadmus Group, Inc., served as the prime contractor providing support forthis
work. The major contributions of Chris Higgins, Aaron Stern, Jonathan Koplos, and Maureen Devitt are
gratefully acknowledged. George Hallberg served as Cadmus' Project Manager.
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Contents
Foreword i
Disclaimer iii
Acknowledgments v
Contents vii
Tables ix
Figures xi
Section 1. Introduction 1
Section 2. The UCMR List Contaminant Selection Process 3
2.1. The CCL Selection and Prioritization Process 4
2.1.1. Microbiological Contaminants 4
2.1.2. Chemical Contaminants 6
2.1.2.1. Occurrence Criterion 7
2.1.2.2. Health Effects Criterion 8
2.1.2.3. Chemical Contaminants on the Final 1998 CCL 9
2.2. The UCMR List Selection Process 11
2.2.1. Lead-210 and Polonium-210 11
2.2.2. Prioritization of Contaminants on the UCMR List 12
2.3. References 13
Notes 13
Section 3. Information on Methods Selected for the UCMR 15
3.1. List 1 Contaminants 16
3.1.1. Volatile Organic Compounds 16
3.1.2. Semivolatile Organic Compounds 16
3.1.3. Chlorinated Hydrocarbon Pesticides 18
3.1.4. Nitrogen- and Phosphorus-Containing Pesticides 18
3.1.5. Acid Herbicides 19
3.1.6. Inorganic Compounds 19
3.2. List 2 Contaminants 19
3.2.1. List 2 Chemical Contaminants 20
3.2.2. List 2 Microbiological Contaminants 23
3.3. Lists Contaminants 24
3.3.1. List 3 Chemical Contaminants 24
3.3.2. List 3 Microbiological Contaminants 24
3.4 References 26
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Technical Background Information for the UCMR March 2000
Notes 27
Section 4. Spatial Distribution 29
4.1. Sources of Information 29
4.1.1. Toxic Release Inventory Database 29
4.1.2. USGS National Pesticide Synthesis Project 29
4.1.3. Census Data 30
4.1.4. Other Sources of Occurrence Information 30
4.2. Findings 31
4.2.1. UCMR (1999) List 1 Contaminants 31
4.2.2. UCMR (1999) List 2 Contaminants 40
4.2.3. UCMR (1999) List 3 Contaminants 50
4.3. Conclusions 51
4.4. References 52
Section 5. The UCMR Sampling Rationale 53
5.1. Sampling Plan for UCMR (1999) List 1 Contaminants 53
5.1.1. Sampling Locations 53
5.1.2. Temporal Variability and Vulnerability 53
5.1.2.1. General Trends 54
5.1.2.2. Synthetic Organic Compounds (SOCs) 54
5.1.2.3. Volatile Organic Compounds (VOCs) 56
5.1.3. Implications For UCMR Monitoring 59
5.2. Sampling Plan for UCMR (1999) List 2 Contaminants 64
5.2.1. Sampling for List 2 Chemical Contaminants 64
5.2.2. Sampling for Aeromonas hydrophila 65
5.2.2.1. Initial Occurrence Data 65
5.2.2.2. Factors Affecting Aeromonas Occurrence 65
5.2.2.3. Aeromonas Sampling 66
5.3. Sampling Plan for UCMR (1999) List 3 Contaminants 67
5.4. References 67
Notes 69
Appendix A. Abbreviations and Acronyms A-1
Appendix B. Definitions B-1
VIII
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Tables
Table 2.1 The 1998 Contaminant Candidate List 3
Table 2.2 Microbiological Contaminants Considered for the CCL (1998) and the UCMR (1999) List 5
Table 2.3 Chemical Contaminants Considered for the CCL and the UCMR List 9
Table 3.1 Approved Analytical Methods for UCMR (1999) List 1 Contaminants 17
Table 3.2 Anticipated Analytical Methods for UCMR (1999) List 2 Contaminants 20
Table 3.3 Possible Analytical Methods for UCMR (1999) List 3 Contaminants 24
Table 4.1 UCMR (1999) List 1 Contaminant Occurrence or Use by EPA Region 32
Table 4.2 UCMR (1999) List 2 Contaminant Occurrence or Use by EPA Region 40
Table 4.3 UCMR (1999) List 3 Contaminant Occurrence or Use by EPA Region 50
Table 5.1 Percentage of Monte Carlo Simulations Within, Over, or Under ± 0.75 ug/L of the Time-
weighted Annual Mean Atrazine Concentration 63
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Figures
Figure 4.1. Acetochlor—Estimated Annual Agricultural Use 33
Figure 4.2. DCPA—Estimated Annual Agricultural Use 34
Figure 4.3. EPIC—Estimated Annual Agricultural Use 35
Figure 4.4. Molinate—Estimated Annual Agricultural Use 36
Figure 4.5. Perchlorate—Confirmed Manufacturers or Users 37
Figure 4.6. Perchlorate—Confirmed Releases 38
Figure 4.7. Terbacil—Estimated Annual Agricultural Use 39
Figure 4.8. Alachlor—Estimated Annual Agricultural Use 43
Figure 4.9. Diazinon—Estimated Annual Agricultural Use 44
Figure 4.10. Disulfoton—Estimated Annual Agricultural Use 45
Figure 4.11. Diuron—Estimated Annual Agricultural Use 46
Figure 4.12. Fonofos—Estimated Annual Agricultural Use 47
Figure 4.13. Linuron—Estimated Annual Agricultural Use 48
Figure 4.14. Terbufos—Estimated Annual Agricultural Use 49
Figure 5.1. Pesticide Concentrations in Surface Waters 55
Figure 5.2. Number of CWSs with Monthly Mean Atrazine Concentrations Above 3.0 ug/L 56
Figure 5.3. Percentage of Surface Water Systems with Detections and Maximum Concentration
Detected, by Month, for Alachlor, Atrazine, and Simazine, in Ohio 57
Figure 5.4. Percentage of Surface Water Systems with Detections and Maximum Concentration
Detected, by Month, for Metolochlor, Metribuzin, Cyanazine, and Acetochlor, in Ohio 58
Figure 5.5. Percentage of Systems with Detections of Xylene, by Month and Water Source, for Three
States 59
Figure 5.6. Percentage of Systems with Detections of Xylene, Toluene, and Benzene, by Month and
Water Source, for Alabama 60
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Technical Background Information for the UCMR March 2000
Figure 5.7. Percentage of Systems with Detections of Tetrachloroethylene and Trichloroethylene, by
Month and Water Source, for Illinois 61
Figure 5.8. Percentage of Systems with Detections (>MRL, >0.5MCL) of Any of the 21 Regulated
VOCs, by Month and Water Source, for Iowa 62
Figure 5.9. Schematic Annual Contaminant Concentration Profile, with Three Sampling Scenarios (A,
B, and C) 63
XII
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Section 1. Introduction
The Unregulated Contaminant Monitoring Regulation (UCMR) is required under § 1445(a)(2) of
the Safe Drinking Water Act (SDWA), as amended in 1996. Under the 1996 Amendments, the Environ-
mental Protection Agency (EPA) is required to publish a list of contaminants to be monitored and to
establish a monitoring program for these contaminants.1 Contaminants on the UCMR List are known or
anticipated to occur in public water systems (PWSs) and may require regulation under SDWA, but
additional data on their occurrence are needed before regulatory decisions can be made. As EPA will use
data collected under the revised UCMR Program in making future regulatory decisions, the monitoring for
the contaminants on the UCMR List is one of the cornerstones of the sound science approach to regulatory
decision making that is an aim of the 1996 Amendments.
There are 36 contaminants listed on the UCMR (1999) List, as published in the September 17,
1999 Federal Register (64 FR 50555). Thirty-four of these contaminants were also included on the 1998
Contaminant Candidate List (CCL) as published in the March 2, 1998 Federal Register (63 FR 10273).
The CCL, as required by §1412(b)(l) of SDWA, lists contaminants that, at the time of publication, were
not subject to any proposed or promulgated national primary drinking water regulations (NPDWRs), were
known or anticipated to occur in PWSs, and which may require regulations. The 1998 CCL is comprised
of 50 chemical and 10 microbiological contaminants and contaminant groups, and is divided into lists of
occurrence, research, and regulation determination priorities (Table 2.1). All 34 of the contaminants
included on both the UCMR (1999) List and the 1998 CCL were listed as occurrence priorities on the
CCL, although other data (i.e., health effects data) may also be needed. The two contaminants included on
the UCMR (1999) List but not included on the 1998 CCL are lead-210 (210Pb) and polonium-210 (210Po).
This document is intended to provide technical background information for the UCMR. Section 2
of this document summarizes the process used to select contaminants for the UCMR (1999) List to be
monitored under the UCMR Program. This process was intimately tied to the process used to select
contaminants forthe 1998 CCL: a brief summary of the CCL selection process is also included. Section 3
of this document provides an overview of the methods approved for monitoring contaminants on List 1 of
the UCMR (1999) List, as well as methods that EPA is developing or will shortly begin developing for
List 2 and List 3 contaminants. Section 4 provides a brief summary of use, environmental release, and
production of all contaminants on the UCMR (1999) List. Finally, Section 5 of this document describes
the rationale used to determine the timing and location (at the water system level) of monitoring for
UCMR contaminants.
Notes
1 Although SDWA stipulates that EPA publish a list of not more than 30 contaminants to be monitored,
EPA is interpreting this to mean that while no more than 30 contaminants can be monitored in any 5-year
UCMR listing cycle, EPA can maintain a list of more than 30 contaminants needing additional occurrence
data.
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Section 2. The UCMR List
Contaminant Selection Process
The UCMR (1999) List, as published in the UCMR (64 FR 50555), is based on the Contaminant
Candidate List (CCL), as published in the March 2, 1998 Federal Register (63 FR 10273). The CCL is
required under SDWA §1412(b)(l) and lists contaminants that, at the time of publication, were not subject
to any proposed or promulgated national primary drinking water regulations (NPDWRs), were known or
anticipated to occur in PWSs, and which may require regulation. The 1998 CCL is composed of 50
chemical and 10 microbiological contaminants/contaminant groups (Table 2.1).
Of the 60 contaminants on the 1998 CCL, 20 are currently listed as regulation determination
priorities (to be evaluated by August 2001 as to whether or not regulations should be developed), and 34
Table 2.1 The 1998 Contaminant Candidate List
Regulatory
Determination
Priorities
Acanthamoeba
(guidance)
1 ,1 ,2,2-tetrachloroethane
1,1-dichloroethane
1 ,2,4-trimethylbenzene
1 ,3-dichloropropene
2,2-dichloropropane
Aldrin
Boron
Bromobenzene
Dieldrin
Hexachlorobutadiene
p-lsopropyltoluene
Manganese
Metolachlor
Metribuzin
Naphthalene
Organotins
Triazines & degradation
products (incl., but not
limited to Cyanazine and
atrazine-desethyl)
Sulfate
Vanadium
Research Priorities
Health Research
Aeromonas
hydrophila
Cyanobacteria (Blue-
green algae), other
freshwater algae, and
their toxins
Calici viruses
Helicobacter pylori
Microsporidia
Mycobacterium avium
intracellulare
(MAC)
1 , 1 -dichloropropene
1 ,3-dichloropropane
Aluminum
DCPA mono-acid & di-
acid degradates
Methyl bromide
MTBE
Perchlorate
Sodium (guidance)
Treatment
Research
Ad enovi ruses
Aeromonas
hydrophila
Cyanobacteria (Blue-
green algae), other
freshwater algae, and
their toxins
Calici viruses
Coxsackievi ruses
(ICR data)
Echoviruses (ICR
data)
Helicobacter pylori
Microsporidia
Mycobacterium avium
intracellulare
(MAC)
Aluminum
MTBE
Perchlorate
Analytical Methods
Research
Adenoviruses
Cyanobacteria (Blue-
green algae), other
freshwater algae,
and their toxins
Caliciviruses
Helicobacter pylon
Microsporidia
1 ,2-diphenylhydrazine
2,4,6-trichlorophenol
2,4-dichlorophenol
2,4-dinitrophenol
2-methyl-Phenol
Acetochlor
Alachlor ESA
Fonofos
Perchlorate
RDX
occurrence r noniies
Adenoviruses
Aeromonas hydrophila
Cyanobacteria (Blue-
green algae), other
freshwater algae, and
their toxins
Caliciviruses
Coxsackieviruses (ICR
data)
Echoviruses (ICR data)
Helicobacter pylori
Microsporidia
1 ,2-diphenylhydrazine
2,4,6-trichlorophenol
2,4-dichlorophenol
2,4-dinitrophenol
2,4-dinitrotoluene
2,6-dinitrotoluene
2-methyl-phenol
Alachlor ESA
Acetochlor
DCPA mono-acid & di-
acid degradates
DDE
Diazinon
Disulfoton
Diuron
EPIC
Fonofos
Linuron
Molinate
MTBE
Nitrobenzene
Perchlorate
Prometon
RDX
Terbacil
Terbufos
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Technical Background Information for the UCMR March 2000
are listed as occurrence priorities (these contaminants have significant gaps in occurrence data that must
be filled before any regulatory decisions can be made). The remaining six contaminants have sufficient
occurrence data available, but other data are needed before they can be considered for regulation (i.e.,
health effects data or efficacy of treatment data). All 34 contaminants listed as occurrence priorities on the
1998 CCL have been included on the UCMR (1999) List. In addition, two other contaminants, lead-210
and polonium-210, were not included on the 1998 CCL but are included on the UCMR (1999) List.
Of the 36 contaminants on the UCMR (1999) List, 12 are on List 1 (to be included in Assessment
Monitoring), 16 are on List 2 (to be included in the Screening Surveys), and 8 are on List 3 (possibly to be
included in Pre-Screen Testing). For more information on the Assessment Monitoring, Screening Survey,
and Pre-Screen Testing components of the UCMR Program, the reader may refer to the UCMR Preamble
and Rule (64 FR 50555).
To understand the selection process for the UCMR List, it is necessary to understand the process
used to select and categorize contaminants for the CCL.1 This process is fundamental to the UCMR List,
as EPA used the list of contaminants categorized as occurrence priorities on the CCL to develop the
UCMR List. In addition, this section briefly explains the process used to prioritize contaminants on the
UCMR List into Lists 1, 2, and 3.
2.1. The CCL Selection and Prioritization Process
The SDWA, as amended in 1996, required EPA to publish the first CCL within 18 months of
enactment (i.e., by February 1998). In addition, the 1996 Amendments stipulated that the selection process
must include consultation and input from the scientific community, and that there must be an opportunity
for public comment prior to publication of the final CCL. To fulfill these requirements, the National
Drinking Water Advisory Council's (NDWAC) Working Group on Occurrence and Contaminant Selection
played an integral role in this process by recommending selection criteria as well as the list of contami-
nants initially considered for the CCL. During the selection process, EPA also sought input from experts
on microbiological contaminants to be included on the CCL through a workshop on microbiology and
public health. EPA also consulted with the Science Advisory Board and relied on input from the public
(including water utilities, trade associations, and environmental groups) through stakeholder meetings and
comments solicited through the October 6, 1997 draft CCL (62 FR 52193).
2.1.1. Microbiological Contaminants
To select microbiological contaminants for the CCL, EPA developed an initial list of 21 microor-
ganisms and groups of microorganisms to be evaluated at a workshop on microbiology and public health
held on May 20-21, 1997. Table 2.2 lists the microbiological contaminants included on this initial list. The
workshop participants developed criteria to evaluate this initial list of contaminants, as well as other
contaminants that were added during workshop discussion. These criteria were:
(1) public health significance;
(2) known waterborne transmission;
(3) occurrence in source water;
(4) effectiveness of current water treatment; and
(5) adequacy of analytical methods.
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Table 2.2 Microbiological Contaminants Considered for the CCL (1998)
and the UCMR (1999) List
Microbiological
Contaminant
Ad enovi ruses
Aeromonas hydrophila
Coxsackievi ruses
Echoviruses
Helicobacter pylori
Microsporidia
(Enterocytozoon bieneust
and Encephalitozoon
[Septata] intestinalis)
Norwalk and other
Calicivi ruses
Cyanobacteria and their
toxins
Acanthamoeba
Mycobacterium avium
Complex (MAC)
Cyclospora cayenanensis
Toxoplasma gondii
Pseudomonas aeruginosa
Arcobacter
Campylobacter
£. Co// O1 57: H7
Hepatitis E
Isospora belli
Rotavirus
Astrovi ruses
Naegleria fovJeri
Hepatitis A
Legionella
Entamoeba histolytica
Salmonella
Shigella
Vibrio spp.
Yersinia enterocolitica
Blastocystis hominis
Picobivirna virus
Picotrivirna virus
Bacteriophage
Pfiesteria piscicidia
Initial list
submitted
to
workshop
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Considered
by Workshop
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Included in
Draft CCI
(1998)
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a
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Not on Draft
CCL (1998)
but
suggested
for inclusion
by Public
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Included
on Final
CCL
(1998)
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Included on
Draft and
Final UCMR
(1999) List
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* While Pseudomonas aeruginosa was not included on the draft or final CCL, EPA had intended to conduct a literature review of
this contaminant before making decisions for the final CCL. This literature review was not, however, completed before publication of
the final CCL. Because of this,Pseudo/T7onas aeruginosa was not considered for the final CCL.
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Technical Background Information for the UCMR March 2000
Using these criteria, the workshop identified a list of 13 microorganisms and groups of microor-
ganisms to be included on the draft CCL (Table 2.2). This list was presented to the NDWAC Working
Group, and after approval, to the full NDWAC. EPA published this list as part of the draft CCL in the
October 6, 1997 Federal Register (62 FR 52193).
Based on comments received on the draft CCL, EPA eliminated four microorganisms [Cyclo-
spora cayetanensis, Toxoplasma gondii, Hepatitis A virus, and Legionella (in ground water)] and added
one group of microorganisms (Cyanobacteria, other freshwater algae, and their toxins) to the CCL. The
rationale for these changes is documented in the March 2, 1998 Federal Register notice announcing the
final 1998 CCL (63 FR 10273).
Cyanobacteria and their toxins were added to the 1998 CCL because EPA decided that: (1)
pathogenic algae and their toxins are not necessarily associated with fecal contamination, and thus may
not be effectively controlled by the Surface Water Treatment Rule (SWTR) or the Enhanced SWTR
(ESWTR), and (2) some data suggest that current treatment techniques may be particularly inadequate in
controlling algal toxins. For more information, the reader may refer to the publication of the final 1998
CCL published in the March 2, 1998 Federal Register (63 FR 10273) and the EPA Drinking Water
Microbiology and Public Health Workshop Summary and the NDWAC Working Group Meeting Summa-
In general, the data available on the occurrence of the microbiological contaminants included on
the final 1998 CCL are very limited. Thus, EPA listed almost all of the microbiological contaminants on
the CCL as occurrence priorities; the only two microbiological contaminants on the final 1998 CCL that
the Agency did not list as occurrence priorities are Acanthamoeba andMycobacterium avium complex.
Acanthamoeba are agroup office-living amoeba that can cause inflammation ofthe eye's cornea, espe-
cially in individuals that wear soft or disposable contact lenses. Although no cases of waterborne disease
have been reported, Acanthamoeba are common in soil and water, and their cysts may be resistant to
chlorine. EPA intends to issue guidance for Acanthamoeba to educate the public about the potential
problems of using tap water to cleanse contact lenses, and has therefore included Acanthamoeba as a
regulation determination priority.
Mycobacterium avium complex (MAC) is a commonly found pathogen capable of causing
pulmonary and other diseases in immuno-compromised individuals. Unlike the other microorganisms on
the 1998 CCL, considerable occurrence data exists for MAC, as several epidemiological studies have
linked nosocomial infections of MAC to water supplies and distribution systems. EPA listed MAC on the
CCL as both a health and treatment research priority, particularly because of its resistance to chlorine, its
ability to colonize pipes, and its public health significance. Although additional occurrence data may be
warranted because of its likely occurrence in biofilms, EPA believes it is inappropriate to include MAC in
a general occurrence study such as the UCMR Program. Instead, EPA believes MAC may require special,
focused studies, aimed at obtaining data on the efficacy of current water treatment technologies in remov-
ing MAC from drinking water.
2.1.2. Chemical Contaminants
At the first NDWAC Working Group meeting held on April 3-4, 1997, a list of 3 91 contaminants
(including 25 microbiological contaminants) was proposed for consideration for the CCL. (The original
list contained 25 microbiological contaminants, but because 4 cyanobacterial toxins were placed in a
single group and the viruses were regrouped, Table 2.2 presents only 21 microbiological contaminants.)
This list was created by combining lists of contaminants from ten separate sources used as logical starting
points for the draft CCL contaminant selection process. These lists included the 1991 Drinking Water
Priority List (DWPL), the Health Advisories (HAs) List, the Integrated Risk Information System (IRIS)
List, a list of Non-Target Analytes in Public Water Supply Samples, the Comprehensive Environmental
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Technical Background Information for the UCMR March 2000
Response, Compensation, and Liability Act (CERCLA) Priority List, the Toxic Release Inventory (TRI)
List, a list of contaminants identified by stakeholders, a list of contaminants identified by the Office of
Pesticide Programs (OPP), a list of contaminants identified by the Safe Drinking Water Hot-line, and a list
of contaminants suspected of causing endocrine disruption.
Of the lists summarized above, the last two were essentially eliminated from initial consideration
because: (1) the Safe Drinking Water Hotline could not ascertain whether calls received were related to
general questions and inquiries or to incidents of contamination, and (2) EPA had established a separate
committee, the Endocrine Disrupter Screening and Testing Advisory Committee (EDSTAC), to address
concerns regarding the screening and evaluation of contaminants suspected of causing endocrine disrup-
tion. However, an interim EPA assessment concluded that for many suspected endocrine disrupters, a
causal relationship between exposure to a specific environmental agent and an adverse health effect in
humans has not been established (with a few exceptions). Decisions for inclusion of contaminants sus-
pected solely of endocrine disruption on the CCL were deferred pending completion of EDSTAC's recom-
mendations and aNational Academy of Sciences (NAS) review, which was completed in 1999.3 Informa-
tion contained within this report as well as EDSTAC's recommendations will be used in the development
of the next CCL, expected in 2003. Contaminants suspected of endocrine disruption that were also in-
cluded on any of the other eight lists remained in consideration.
The NDWAC Working Group combined the first 8 lists, and after both eliminating duplicate
contaminants and contaminants subject to NPDWRs and relegating the microorganisms to the expert
panel, an initial list of 262 chemical contaminants was identified for consideration for the draft CCL.
These contaminants were then subjected to criteria developed by the Working Group.4 The selection
criteria are described below. Data used in the screening process were obtained from EPA's Storage and
Retrieval System (STORET), the Hazardous Substances Database (HSDB), IRIS, published literature,
various EPA reports and documents, EPA's Unregulated Contaminant Information System (URCIS), the
U.S. Geological Survey's National Water Quality Assessment (NAWQA), the National Inorganic and
Radionuclide Survey (NIRS), EPA's Pesticides in Ground Water Database (PGWD), and the National
Pesticides Survey (NPS).
2.1.2.1. Occurrence Criterion
The Working Group evaluated the initial 262 chemical contaminants with regard to their occur-
rence before considering health effects. An affirmative response to any of the occurrence-related questions
resulted in the contaminant being evaluated for health effects. These questions, and the criteria needed for
an affirmative response, are listed below.
(1) Was the contaminant looked for and found in drinking water, or in a major drinking water
source, or in ambient water at levels that would trigger concern about human health?
To judge if a contaminant was looked for and found in drinking water, it must have been included
in a major survey (defined as one including a population of at least 100,000, 2 or more states, or 10 or
more small PWSs) or in a data set such as EPA's URCIS.
To judge if a contaminant was looked for and found in a major drinking water source, or in
ambient water, any source of occurrence data was used. Major sources were defined as sources supplying
a population of at least 100,000, or 2 or more states. Levels that would trigger human health concern were
defined as levels within an order of magnitude of concentrations likely to cause health effects, or at least
50 percent of samples with levels at 50 percent (or greater) of concentrations likely to cause health effects.
If data indicated occurrence at levels that would trigger human health concern (as defined above) for a
population of at least 100,000, in 2 or more states, or in 10 or more small PWSs, this criterion was judged
as having been met.
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Technical Background Information for the UCMR March 2000
(2) If the contaminant was not looked for, is it likely to be found in water, based on surrogates for
occurrence?
To judge if a contaminant was likely to be found, the following surrogates were examined:
TRI releases. If a contaminant was released to surface water in excess of 400,000 pounds per
year (400,000 is the cutoff for the top 15 TRI chemicals released in 1995), and the physical-
chemical properties indicated persistence and mobility, then this criterion was judged as
having been met.
Production Volumes. If a contaminant was produced in excess of 10 billion pounds per year,
and the physical-chemical properties indicated persistence and mobility, then this criterion was
judged as having been met.
OPP Ground Water (GW) Risk. If a contaminant had an OPP GW Risk value of 2.0 or
greater, then this criterion was judged as having been met. However, in the late stages of the
screening process, the Working Group decided to defer contaminants only having an OPP GW
Risk value of 2.0 or greater (i.e., there was no other supporting data), pending further evalua-
tion of the potential occurrence of these contaminants at levels of health concern.
2.1.2.2. Health Effects Criterion
Once a chemical met the occurrence criterion, the Working Group then evaluated it with respect to
its potential health effects on humans. If the health effects criterion was also met, then the chemical was
included on the draft CCL. This criterion essentially asked if there was evidence, or suspicion, that the
contaminant adversely affects human health. To satisfy the health effects criterion, the chemical had to:
(1) be listed by California Proposition 65;
(2) have an EPA Health Advisory;
(3) be a likely (based on animal data) or known (based on human data) carcinogen by EPA or the
International Agency for Research on Cancer (IARC);
(4) be included in more than one epidemiological study indicating adverse health effects;
(5) have an oral value (reference dose) in IRIS;
(6) be regulated in drinking water by another industrialized country;
(7) be a member of a chemical family of known toxicity; or
(8) have a structural activity relationship indicating toxicity.
If a chemical satisfied both the occurrence criterion and the health effects criterion, it was included
on the draft CCL. There were 55 chemicals that satisfied this criterion, and 3 additional chemicals that
EPA included on the draft CCL for other reasons.5 EPA published the list of 58 chemical contaminants as
part of the draft CCL in the October 6, 1997 Federal Register (62 FR 52193).
-------
Technical Background Information for the UCMR
March 2000
2.1.2.3. Chemical Contaminants on the Final 1998 CCL
Many public comments were received pertaining to the chemical contaminants included on the
draft CCL. These comments were reviewed by EPA and the NDWAC Working Group, and a final CCL
was first approved by the Working Group, and then the full NDWAC. Of the 58 chemicals listed on the
draft CCL, EPA removed 8 chemicals from the list, combined 2 chemicals into a single chemical group,
and added 1 chemical to create the final 1998 CCL, as published in the March 2, 1998 Federal Register
(63 FR 10273). The complete rationale for these revisions is documented in the March 2, 1998 notice.
EPA moved to include triazines and their degradation products (i.e., cyanazine and atrazine-
desethyl)asagroup on the final 1998 CCL, rather than as individual contaminants. The Agency made this
decision in light of comments received regarding other triazine degradation products not included on the
draft CCL, as well as a stakeholder request that EPA address these chemicals as a group. In addition,
many comments suggested the inclusion of perchlorate on the final CCL. Although it was not included on
the draft CCL, the October 6, 1997 Federal Register notice specifically solicited comments on perchlor-
ate, as information pertaining to its occurrence had just recently come to light at the time of publication.
With strong public support for including it, EPA decided to include perchlorate on the final CCL despite
the gaps in supporting data.
Of the 50 chemical contaminants included on the final CCL, the Agency determined that 26
contaminants have significant gaps in occurrence data. These contaminants were therefore listed as
occurrence priorities (see Table 2.1). EPA found that 19 chemical contaminants had sufficient occurrence
data to be listed as regulatory determination priorities. Data for these contaminants are available from the
same data sources used for the occurrence criterion. Additional research is needed for five other chemical
contaminants: 1,1-dichloropropene, 1,3-dichloropropane, methyl bromide, aluminum, and sodium. EPA
did not list these contaminants as occurrence priorities, since sufficient occurrence data are available from
URCIS (for 1,1-dichloropropene, 1,3-dichloropropane, and methyl bromide) and NIRS (for aluminum and
sodium). Table 2.3 presents the chemical contaminants that were listed as occurrence priorities, as well as
the chemical contaminants on the UCMR (1999) List.
Table 2.3 Chemical Contaminants Considered for the CCL and the UCMR List
Chemical Contaminant
1 ,2-diphenylhydrazine
2,4-dichlorophenol
2,4-dinitrophenol
2,4-dinitrotoluene
2,4,6-trichlorophenol
2,6-dinitrotoluene
2-methyl-phenol o-cresol)
Acetochlor
Alachlor ESA
DCPA di-acid degradate
DCPA mono-acid degradate
DDE
Diazinon
Disulfoton
CASRN
122-66-7
120-83-2
51-28-5
121-14-2
88-06-2
606-20-2
95-48-7
34256-82-1
2136-79-0
887-54-7
72-55-9
333-41-5
298-04-4
Included
on Draft
CCL
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Included
on Final
CCL
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Included on
Occurrence
Priorities List
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Included
on
proposed
UCMR List
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Included
on final
UCMR
List
•
•
•
•
•
•
•
•
•
•
•
•
•
•
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Technical Background Information for the UCMR
March 2000
Table 2.3 Chemical Contaminants Considered for the CCL and the UCMR List (Continued)
Chemical Contaminant
Diuron
EPIC
(s-ethyldipropylthiocarba-mate)
Fonofos
Linuron
Methyl tertiary-butyl ether (MTBE)
Molinate
Nitrobenzene
Prometon
Terbacil
Terbufos
RDX
Perchlorate
Lead-210
Polonium-210
1,1-dichloroethane
1,1-dichloropropene
1 ,1 ,2,2-tetrachloroethane
1 ,2,4-trimethylbenzene
1 ,3-dichloropropane
1 ,3-dichloropropene (telone or
1 ,3-D)
2,2-dichloropropane
Aldrin
Aluminum
Boron
Bromobenzene
Dieldrin
Hexachlorobutadiene
p-lsopropyltoluene (p-Cymene)
Manganese
Methyl bromide
Metolachlor
Metribuzin
Naphthalene
Organotins
Sodium
Sulfate
CASRN
330-54-1
759-94-4
944-22-9
330-55-2
1634-04-4
2212-67-1
98-95-3
1610-18-0
5902-51-2
13071-79-9
121-82-4
14797-73-0
14255-04-0
13981-52-7
75-34-3
563-58-6
79-34-5
95-63-6
142-28-9
542-75-6
594-20-7
309-00-2
7429-90-5
7440-42-8
108-86-1
60-57-1
87-68-3
99-87-6
7439-96-5
74-83-9
51218-45-2
21087-64-9
91-20-3
7440-23-5
Included
on Draft
CCL
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Included
on Final
CCL
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Included on
Occurrence
Priorities List
•
•
•
•
•
•
•
•
•
•
•
•
Included
on
proposed
UCMR List
•
•
•
•
•
•
•
•
•
•
Included
on final
UCMR
List
•
•
•
•
•
•
•
•
•
•
•
•
•
•
10
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Technical Background Information for the UCMR
March 2000
Table 2.3 Chemical Contaminants Considered for the CCL and the UCMR List (Continued)
Chemical Contaminant
Triazines
Vanadium
Atrazine-desethyl
Cyanazine
2,6-di-tert-butyl-p-benzoquinone
(DTBB)
Acetone
Aldicarbs
Dimethoate
Isopropylbenzene (cumene)
Nickel
Rhodamine WT
Zinc
CASRN
7440-62-2
6190-65-4
21725-46-2
719-22-2
67-64-1
60-51-5
98-82-8
7440-66-6
Included
on Draft
CCL
a
•
•
•
•
•
•
•
•
•
•
•
Included
on Final
CCL
•
•
a
a
Included on
Occurrence
Priorities List
Included
on
proposed
UCMR List
Included
on final
UCMR
List
a EPA combined atrazine-desethyl and cyanazine, which both appeared on the draft CCL, into a single contaminant group, the
triazines, for the final CCL. This group includes all triazines and their degradation products, including, but not limited to, atrazine
desethyl and cyanazine.
2.2. The UCMR List Selection Process
EPA used the 1998 CCL as the basis for the proposed UCMR (1999) List of contaminants. All of
the contaminants selected for the proposed UCMR (1999) List were listed as occurrence priorities in Table
2 of the final CCL Federal Register notice of March 2, 1998 (63 FR 10273). Only two contaminants,
RDX and perchlorate, were listed as occurrence priorities but were not included on the proposed UCMR
(1999) List. It was initially thought that both RDX and perchlorate would exhibit localized patterns of
occurrence, and thus monitoring for these contaminants under a national monitoring program such as the
UCMR might not be necessary. However, subsequent data collected by the Interagency Perchlorate
Steering Committee (IPSC) indicate perchlorate occurrence is likely to be more widespread. Furthermore,
many public comments were received in support of the inclusion of both perchlorate and RDX on the final
UCMR (1999) List. For these reasons, EPA moved to include both of these contaminants on the final
UCMR (1999) List.
2.2.1. Lead-210 and Polonium-210
In the Preamble to the proposed UCMR (64 FR 23398), EPA requested public comment on the
possible inclusion on the final UCMR (1999) List of two contaminants that were not identified through the
CCL Process. These contaminants, lead-210 (210Pb) and polonium-210 (210Po), are naturally occurring
radionuclides with health concerns at low levels. Both nuclides are in the uranium decay series along with
radium-226 and radon-222. Lead-210 with a half life of 22 years, and one of its progeny, polonium-210,
with a half life of 138 days, have been found in drinking water. The occurrence of these contaminants in
shallow aquifers has been documented in Florida (Harada etal, 1989; Upchurch 1991) and EPA is aware
of their occurrence in at least two other States. Because of potential occurrence and consequent health
risks, EPA solicited public comments on the inclusion of lead-210 and polonium-210 on the UCMR
(1999) List. After receiving public support for their inclusion, EPA moved to include both lead-210 and
polonium-210 on the final UCMR (1999) List.
11
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Technical Background Information for the UCMR March 2000
2.2.2. Prioritization of Contaminants on the UCMR List
Once selected for the UCMR (1999) List, EPA then divided the contaminants into three separate
monitoring lists, primarily on the basis of the availability of analytical methods. Section 3 of this docu-
ment provides a more detailed discussion of methods availability. The rationale for these divisions is that
while EPA intends to monitor for most of the contaminants on the UCMR (1999) List, suitable methods
are not yet available for all of the contaminants. A suitable method is defined as an EPA-evaluated method
with a proven track record of providing consistent, quality data on the occurrence of the analyte, and
whose cost would not prohibit its use on a national scale. In accordance with § 12(d) of the National
Technology Transfer and Advancement Act, EPA has approved the use of appropriate voluntary consensus
standards for monitoring contaminants on the UCMR List. Methods only published in peer-reviewed
literature are not considered suitable because they have often not undergone extensive field-testing, they
may not be suitable for routine sampling by PWSs or for routine laboratory implementation, and they may
not produce consistent results.
Contaminants for which suitable methods are currently available are included on List 1 of the
UCMR (1999) List.6 There are a total of 12 chemical contaminants on List 1 which will be monitored
under the Assessment Monitoring component of the UCMR Program. EPA initially proposed 10 chemical
contaminants and 1 microbiological contaminant for List 1 of the UCMR (1999) List. At the time of
publication of the final UCMR (September 1999), EPA approved analytical methods for these 10 chemical
contaminants, but indicated that suitable analytical methods for two additional chemical contaminants,
acetochlor and perchlorate, would be available shortly. On March 2, 2000, EPA published a direct and
final Rule (65 FR 11371) approving the use of analytical methods for monitoring acetochlor and perchlor-
ate under the Assessment Monitoring component of the UCMR. Monitoring for all 12 chemical contami-
nants is to begin in 2001. In the proposed UCMR (64 FR 23398), EPA also included one microbiological
contaminant, Aeromonas hydrophila, on List 1. However, after additional review of the proposed analyti-
cal method for Aeromonas, and with extensive public concerns about the use of this method, EPA moved
Aeromonas hydrophila to List 2 for the final UCMR. For the entire UCMR Program, and particularly for
these contaminants, EPA has developed specific quality control procedures that must be followed when
conducting analyses for the UCMR(§141.40(a)(5)). These procedures are outlined in the UCMR Analyti-
cal Methods and Quality Control Manual (EPA 815-R-99-004) and its Supplement (EPA 815-R-00-002).
List 2 contaminants are those for which EPA is currently refining analytical methods. Develop-
ment of these methods should be completed in time for Screening Surveys to be conducted in 2001 and
2003. EPA initially included 14 chemical contaminants on List 2 of the proposed UCMR (1999) List.
With the addition of polonium-210 and RDX to the UCMR (1999) List, as well as the movement of
acetochlor from List 2 to List 1 and Aeromonas hydrophila from List 1 to List 2, there are currently 15
chemicals and 1 microorganism on List 2 of the UCMR (1999) List.
All remaining contaminants on the UCMR List are included on List 3. List 3 contaminants are
those for which EPA has begun or shortly will begin analytical methods development, but completion of
those efforts is not expected prior to the Assessment Monitoring or Screening Surveys required under the
initial implementation of the UCMR. Instead, EPA may monitor some of these contaminants through the
Pre-Screen Testing component of the UCMR Program, to be conducted in 2004. In the proposed UCMR,
EPA included seven microbiological contaminants on List 3. After the addition of lead-210 to the UCMR
(1999) List, List 3 of the final UCMR (1999) List includes seven microbiological contaminants and 1
chemical contaminant.
12
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Technical Background Information for the UCMR March 2000
2.3. References
Harada, Koh, W.C. Burnett, P.A. LaRock, and J.B. Cowart. 1989. Polonium in Florida groundwater and
its possible relationship to the sulfur cycle and bacteria. Geochemica et Cosmochimica Acta. 53:143-
150.
Upchurch, S .B. 1991. Radiochemistry of Uranium-Series Isotopes in Groundwater. Florida Institute of
Phosphate Research (05-022-092)
Notes
lrThe selection process for the CCL is well documented, and for more information, the reader may
refer to the Federal Register notices announcing the draft CCL (October 6, 1997; 62 FR 52193) and the
final CCL (March 2, 1998; 63 FR 10273).
2These summaries may be obtained from the EPA Water Docket, (202) 260-3027, Docket Number
W-97-11. General information on the UCMR and the CCL can also be obtained from the EPA Safe
Drinking Water Hotline, (800) 426-4791, or through the EPA Office of Ground Water and Drinking Water
Internet Home page at http://www.epa.gov/safewater.
3The NAS report, entitled Hormonally Active Agents in the Environment, is available from the
National Academy Press, 2101 Constitution Avenue, NW, Lockbox 285, Washington, DC 20055, or http:/
/www.nap.edu.
4A11 contaminants, with the exceptions of nickel, sulfate, and aldicarb and its degradates, were
evaluated with respect to these criteria. EPA included these contaminants on the draft CCL because it had
previously made commitments to complete regulatory action for them.
5As previously noted, EPA included nickel, sulfate, and aldicarb and its degradates, on the draft
CCL because of the Agency's prior commitments to complete regulatory action for these contaminants.
6For more information, the reader may refer to Section 3 of this document or the UCMR Analyti-
cal Methods and Quality Control Manual and its supplement (EPA 815-R-99-004).
13
-------
14
-------
Section 3. Information on Methods
Selected for the UCMR
The UCMR (1999) List, as published in the UCMR (64 FR 50555), includes 36 contaminants,
not all of which are to be monitored at any one time. The UCMR List itself is divided into three lists (Lists
1, 2, and 3), primarily on the basis of the availability and demonstrated quality of analytical methods. The
12 contaminants included on List 1 are those that have analytical methods available that are sufficiently
developed and suited for monitoring. EPA has reviewed these methods and has established that they will
provide consistent, high quality data on the occurrence of the analyte, and that the cost of the method will
not prohibit its use on a national scale. All List 1 contaminants will be monitored under the Assessment
Monitoring component of the UCMR Program to be conducted from 2001 to 2003. EPA is currently
conducting analytical methods development for the 16 contaminants included on List 2, to be included in
the Screening Survey component of the UCMR Program. It is anticipated that suitable analytical methods
will be available for many of these compounds in time for these contaminants to be included in one of the
two Screening Surveys, to be conducted in 2001 and 2003. Although EPA is also conducting analytical
methods development for the eight contaminants included on List 3, seven of these contaminants are
microbiological in nature, and it is anticipated that methods for these contaminants will be particularly
problematic. Some of the List 3 contaminants may be included in the Pre-Screen Testing component of the
UCMR Program to be conducted in 2004. For more information on the Screening Survey and Pre-Screen
Testing components of the revised UCMR Program, the reader may refer to the UCMR Preamble and
Rule (64 FR 50555).
The purpose of the UCMR Program is to obtain occurrence data to support future regulatory
decisions. The data required to make these decisions must be of high quality. All analytical methods are
subject to some degree of false-negative test results (not detecting an analyte when it is present), false-
positive test results (either incorrectly identifying or detecting an analyte, or introducing an analyte into a
sample when it is not present), and errors in the accuracy and precision of quantitative results. Methods
that yield significant false-negatives, false-positives, or other substantial errors would not provide the
quality of data that is needed to support regulatory decisions, and thus are not approved for use.
In addition, the ability to correctly identify a chemical contaminant is directly related to the type of
chemical and the analytical method used. For example, compounds such as disinfection byproducts are far
less likely to be misidentified than pesticides or herbicides because they are typically present at relatively
high concentrations in disinfected waters, while pesticides and herbicides are much less likely to be
present, or are present at much lower concentrations. The analytical method used will also determine the
accuracy of the qualitative identification. In general, the most reliable qualitative identifications come from
methods that use mass spectral data for analyte identification. However, these methods are typically less
sensitive than methods that rely on less selective detectors.
To ensure that the data collected under this regulation are of sufficient quality to meet the require-
ments of these regulatory decisions, EPA has specified that only the analytical methods listed in Table 2 be
used in obtaining data for List 1 contaminants (§141.40(a)(5)).1 In accordance with § 12(d) of the National
Technology Transfer and Advancement Act, EPA has approved the use of appropriate voluntary consensus
standards for monitoring List 1 contaminants. For all contaminants on the UCMR List, methods published
only in peer-reviewed literature are not considered suitable because they have often not undergone ad-
equate validation and may not produce consistent results in routine application by numerous laboratories.
To ensure adequate quality control, analyses for all approved methods (including EPA methods and
voluntary consensus standards) must be conducted using the quality control procedures listed in the
15
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Technical Background Information for the UCMR March 2000
methods as well as those specified in the regulation and described in the UCMR Analytical Methods and
Quality Control Manual (EPA 815-R-99-004) and its supplement (EPA 815-R-00-002) (§141.40(a)(5)).
When procedures listed in the method conflict with those listed in the regulation, the procedures listed in
the regulation should be followed.
3.1. List 1 Contaminants
Contaminants for which suitable methods are currently available are included on List 1 of the
UCMR (1999) List (Table 3.1). There are a total of 12 chemical contaminants included on List 1 that will
be monitored under the Assessment Monitoring component of the UCMR Program. EPA approved specific
analytical methods for the detection of these contaminants, and monitoring is to begin in 2001. The
methods approved for each contaminant are reviewed below.
3.1.1. Volatile Organic Compounds
Methyl Tertiary-Butyl Ether (MTBE) - EPA Method 524.2 can be used to accurately determine both
the qualitative presence and quantitative concentration of MTBE in drinking water. EPA Method 524.2 is
a purge and trap, gas chromatography/mass spectrometry (GC/MS) method for the determination of a
broad range of organics. Analyte preservation studies conducted using the storage conditions detailed in
this method demonstrate that aqueous samples can be held for up to 14 days with minimal analyte degra-
dation. Therefore, EPA has included MTBE on List 1 for Assessment Monitoring. In addition, three
voluntary consensus standards, ASTM D5790.95, SM6210D, and SM6200B have been approved for use
in measuring MTBE in drinking water (Complete references for these methods are listed in Table 3.1).
However, if SM6200B is to be used for monitoring MTBE under the UCMR, sample preservation should
be conducted as specified in EPA Method 524.2.
Nitrobenzene - EPA Method 524.2 can be used to accurately determine both the qualitative presence and
quantitative concentration of nitrobenzene in drinking water. EPA Method 524.2 is a purge and trap, GC/
MS method forthe determination of abroad range of organics. Analyte preservation studies conducted
using the storage conditions detailed in this method demonstrate that aqueous samples can be held for up
to 14 days with minimal analyte degradation. Therefore, EPA has included nitrobenzene on List 1 for
Assessment Monitoring. In addition, three voluntary consensus standards, ASTM D5790.95, SM6210D,
and SM6200B have been approved for use in measuring nitrobenzene in drinking water. However, if
SM6200B is to be used for monitoring nitrobenzene under the UCMR, sample preservation should be
conducted as specified in EPA Method 524.2.
3.1.2. Semivolatile Organic Compounds
2,4-dinitrotoluene - EPA Method 525.2 can be used to accurately determine both the qualitative presence
and quantitative concentration of 2,4-dinitrotoluene in drinking water. EPA Method 525.2 is a 1 liter solid
phase extraction/GC/MS (SPE/GC/MS) method forthe determination of abroad range of organics.
Analyte preservation studies conducted using the storage conditions detailed in the method demonstrate
that aqueous samples can be held for up to 14 days, and extracts for up to 30 days with minimal analyte
degradation. Therefore, EPA has included 2,4-dinitrotoluene on List 1 for Assessment Monitoring. No
equivalent voluntary consensus standards for measuring 2,4-dinitrotoluene in drinking water have been
approved for monitoring under the UCMR.
2,6-dinitrotoluene - EPA Method 525.2 can be used to accurately determine both the qualitative presence
and quantitative concentration of 2,6-dinitrotoluene in drinking water. EPA Method 525.2 is a 1 liter SPE/
GC/MS method forthe determination of abroad range of organics. Analyte preservation studies conducted
using the storage conditions detailed in the method demonstrate that aqueous samples can be held for up to
16
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Technical Background Information for the UCMR
March 2000
Table 3.1 Approved Analytical Methods for UCMR (1999) List 1 Contaminants
Chemical Contaminant
CASRN
Methodology
EPA Method
Equivalent Methods
Volatile Organic Compounds
MTBE
Nitrobenzene
1634-04-4
98-95-3
EPA 524.2 a
EPA 524.2 a>e
D5790-95b;SM6210Dc;
SM6200B c
D5790-95b;SM6210Dc;
SM6200B c
Semivolatile Organic Compounds
2,4-Dinitrotoluene
2,6-Dinitrotoluene
121-14-2
606-20-2
EPA 525.2 a
EPA 525.2 a
none identified
none identified
Chlorinated Hydrocarbon Pesticides
DDE
72-55-9
EPA 525.2 a; EPA 508 a; EPA 508.1 a
D581 2-96 b; 990.06 d
Nitrogen- and Phosphorus-Containing Pesticides
Acetochlor
EPIC
Molinate
Terbacil
34256-82-1
759-94-4
2212-67-1
5902-51-2
EPA 525.2 a
EPA 525.2 *; EPA 507 *
EPA 525.2 *; EPA 507 a
EPA 525.2 a; EPA 507 a
none identified
D5475-93 b; 991 .07 d
D5475-93b;991.07d
D5475-93b;991.07d
Acid Herbicides
DCPA mono-acid degradate
DCPA di-acid degradate
887-54-7
2136-79-0
EPA 515.1 a, e; EPA 515.2 a, e
EPA 515.1 a, e; EPA 515.2 a>e
D531 7-93 b; 992.32 d
D531 7-93 b; 992.32 d
Inorgnanic Compounds
Perchlorate
14797-73-0
EPA 31 4.0 f
None identified
a The version of the EPA methods approved for the UCMR are listed at 40 CFR 1 41 .24 (e).
b Annual Book of ASTM Standards, 1996 and 1998, Vol. 11.02, American Society for Testing and Materials. Method D5812-96 is
located in the Annual Book of ASTM Standards, 1 998, Vol. 1 1 .02. Methods D5790-95, D5475-93, and D531 7-93 are located in the
Annual Book of ASTM Standards, 1 996 and 1 998, Vol 1 1 .02. Copies may be obtained from the American Society for Testing and
Materials, 100 Barr Harbor Drive, West Conshohocken, PA 19428.
0 SM 6200 B is only found in the 20th edition of Standard Methods for the Examination of Water and Wastewater, 1 998. Sample
preservation must be conducted as specified in EPA Method 524.2. SM 6210 D is only found in the 18th and 19th editions of
Standard Methods for the Examination of Water and Wastewater, 1992 and 1995, American Public Health Association; either
edition may be used. Copies may be obtained from the American Public Health Association, 1015 Fifteenth Street NW,
Washington, DC 20005.
d Official Methods of Analysis of AOAC (Association of Official Analytical Chemist) International, Sixteenth Edition, 4th Revision,
1998, Volume I, AOAC International, First Union National Bank Lockbox, PO Box 75198, Baltimore, MD 21275-5198. (800) 379-
2622.
e EPA has included specific recommendations regarding the use of EPA Method 524.2 for measuring nitrobenzene and EPA
Methods 515.1 and 515.2 for measuring the DCPA degradates in the UCMR Analytical Methods and Quality Control Manual.
f Copies of EPA Method 314.0, Determination of Perchlorate in Drinking Water Using Ion Chromatography (EPA 81 5-B-99-003)
may be obtained by contacting the EPA Safe Drinking Water Hotline at (800) 426-4791 , or accessing the method directly at
http://www.epa.gov/safewater/methods/sourcalt.html.
14 days, and extracts for up to 30 days with minimal analyte degradation. Therefore, EPA has included
2,6-dinitrotoluene on List 1 for Assessment Monitoring. No equivalent voluntary consensus standards for
measuring 2,6-dinitrotoluene in drinking water have been approved for monitoring under the UCMR.
17
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Technical Background Information for the UCMR March 2000
3.1.3. Chlorinated Hydrocarbon Pesticides
l,l-dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE) - EPA Method 525.2, EPA Method 508, and EPA
Method 508.1 can be used to accurately determine the quantitative concentration of DDE in drinking
water. EPA Method 525.2 is a 1 liter SPE/GC/MS method for the determination of a broad range of
organics. EPA Method 508 is a 1 liter liquid-liquid extraction/GC/electron capture detector (LLE/GC/
ECD) method. EPA Method 508.1 is a 1 liter SPE/GC/ECD method. Analyte preservation studies con-
ducted using the storage conditions detailed in the methods demonstrate that aqueous samples can be held
for up to 7-14 days, and extracts for up to 30 days, with minimal analyte degradation, depending on the
method used. Therefore, EPA has included 4,4'-DDE on List 1 for Assessment Monitoring. However, the
biocide used in EPA Method 508, mercuric chloride, has been withdrawn because of concerns over the
disposal of samples. Without the use of a biocide, microbial degradation of the analyte may occur. Two
voluntary consensus standards, ASTM D5812.96 and AOAC 990.06, have been approved for use in
measuring DDE in drinking water.
3.1.4. Nitrogen- and Phosphorus-Containing Pesticides
Acetochlor - EPA Method 525.2 can be used to accurately determine both the qualitative presence and
quantitative concentration of acetochlor in drinking water. EPA Method 525.2 is a 1 liter SPE/GC/MS
method for the determination of a broad range of organics. Analyte preservation studies conducted using
the storage conditions detailed in the method demonstrate that aqueous samples can be held for up to 14
days, and extracts for up to 30 days with minimal analyte degradation. Therefore, EPA has included
acetochlor on List 1 for Assessment Monitoring. No equivalent voluntary consensus standards for measur-
ing acetochlor in drinking water have been approved for monitoring under the UCMR.
S-Ethyl-Dipropylthio-carbamate (EPTC) - EPA Method 525.2 and EPA Method 507 can be used to
accurately determine the quantitative concentration of EPTC in drinking water. EPA Method 525.2 is a
SPE/GC/MS method for the determination of abroad range of organics. EPA Method 507 is a 1 liter
LLE/GC/nitrogen-phosphorus detector (LLE/GC/NPD) method. Analyte preservation studies conducted
using the storage conditions detailed in these methods demonstrate that aqueous samples can be held for
up to 14 days, and extracts for up to 14-30 days, with minimal analyte degradation, depending upon the
method used. Therefore, EPA has included EPTC on List 1 for Assessment Monitoring. However, the
biocide used in EPA Method 507, mercuric chloride, has been withdrawn because of concerns over the
disposal of samples. Without the use of abiocide, microbiological degradation of the analyte may occur.
Two voluntary consensus standards, ASTM D5475-93 and AOAC 991.07, have been approved for use in
measuring EPTC in drinking water.
Molinate - EPA Method 525.2 and EPA Method 507 can be used to accurately determine the quantitative
concentration of molinate in drinking water. EPA Method 525.2 is a SPE/GC/MS method for the determi-
nation of a broad range of organics. EPA Method 507 is a 1 liter LLE/GC/NPD method. Analyte preser-
vation studies conducted using the storage conditions detailed in these methods demonstrate that aqueous
samples can be held for up to 14 days, and extracts for up to 14-30 days with minimal analyte degrada-
tion, depending upon the method used. Therefore, EPA has included molinate on List 1 for Assessment
Monitoring. However, the biocide used in EPA Method 507, mercuric chloride, has been withdrawn
because of concerns over the disposal of samples. Without the use of abiocide, microbiological degrada-
tion of the analyte may occur. Two voluntary consensus standards, ASTM D5475-93 and AOAC 991.07,
have been approved for use in measuring molinate in drinking water.
Terbacil - EPA Method 525.2 and EPA Method 507 can be used to accurately determine the quantitative
concentration of terbacil in drinking water. EPA Method 525.2 is a SPE/GC/MS method for the determi-
nation of a broad range of organics. EPA Method 507 is a 1 liter LLE/GC/NPD method. Analyte preser-
vation studies conducted using the storage conditions detailed in these methods demonstrate that aqueous
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Technical Background Information for the UCMR March 2000
samples can be held for up to 14 days, and extracts for up to 14-30 days with minimal analyte degrada-
tion, depending upon the method used. Therefore, EPA has included terbacil on List 1 for Assessment
Monitoring. However, the biocide used in EPA Method 507, mercuric chloride, has been withdrawn
because of concerns over the disposal of samples. Without the use of abiocide, microbiological degrada-
tion of the analyte may occur. Two voluntary consensus standards, ASTM D5475-93 and AOAC 991.07,
have been approved for use in measuring terbacil in drinking water.
3.1.5. Acid Herbicides
Dimethyl Tetrachloroterephthalate (DCPA) mono- and di-acid degradates -No analytical methods
that were capable of determining these analytes separately and that could be implemented at reasonable
costs were identified. Three EPA methods were identified that are capable of determining either the total of
the mono- and di-acid forms or the total of the parent DCPA plus both the mono- and di-acid forms. Both
EPA Method 515.1 and EPA Method 515.2 contain amethylene chloride wash following hydrolysis. The
DCPA parent compound is removed during this sample wash step. EPA Method 515.3 does not contain
this solvent wash following hydrolysis, therefore, all three forms of DCPA are measured as a total value
with this method. Because of this, EPA Method 515.3 cannot be used for monitoring these contaminants
for the UCMR. EPA has included DCPA mono- and di-acid degradates on List 1 for Assessment Monitor-
ing, and is requiring that systems use either EPA Method 515.1 or 515.2, or an approved voluntary
consensus standard for these compounds. Documented analyte preservation studies were performed for
these methods, although biological stabilization studies were only performed for EPA Method 515.1.
However, the biocide used in EPA Method 515.1, mercuric chloride, has been withdrawn because of
concerns over the disposal of samples. In addition, two voluntary consensus standards, ASTM D5317.93
and AOAC 992.32, have been approved for use in measuring the DCPA mono- and di-acid degradates in
drinking water. Because the approved methods do not allow for the identification and quantification of the
individual acids, the single analytical result obtained from these methods should be reported under the
UCMR as total DCPA mono- and di-acid degradates.
3.1.6. Inorganic Compounds
Perchlorate - EPA Method 314.0 can be used to accurately determine the quantitative concentration of
perchlorate in drinking water. EPA Method 314.0 is an ion chromatography method that utilizes an ion
chromatographic pump, sample injection valve, guard column, analytical column, suppressor device, and
conductivity detector. Because of interference from common anions such as chloride and sulfate, EPA
Method 314.0 recommends the use of Dionex AG16/AS16 columns. Other guard and separator column
sets, such as AG5/AS5 and AG1 I/AS 11, can be used, although performance of these columns decreased
at higher common anion levels in EPA's validation study of the method. EPA Method 314.0 also requires
the determination of the conductivity of the matrix prior to analysis, so that appropriate steps (i.e., pre-
treatment or dilution) can be taken to minimize the impact of elevated concentrations of common anions.
No voluntary consensus standards have been approved for use in measuring perchlorate in drinking water.
However, EPA notes that laboratories currently using either of the methods for perchlorate published by
the California Department of Health or Dionex Corporation can convert to using EPA Method 314.0
simply by adopting the quality control specified in EPA Method 314.0 without needing to change any
other aspects for their analyses.
3.2. List 2 Contaminants
List 2 contaminants are those for which EPA is currently refining analytical methods. These
contaminants, as well as the anticipated analytical methods, are listed in Table 3.2. It is expected that
analytical methods development for many of these contaminants will be completed in time for their inclu-
sion in the Screening Surveys most likely to be conducted between 2001 and 2003. At this time, there are
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Technical Background Information for the UCMR
March 2000
15 chemical contaminants and 1 microbiological contaminant on List 2. All of the methods being refined
and/or developed for each contaminant are reviewed below.
Table 3.2 Anticipated Analytical Methods for UCMR (1999) List 2 Contaminants
Contaminant
CASRN
Anticipated Analytical Methods
Chemical Contaminants
1 ,2-diphenylhydrazine
2-methyl-phenol
2,4-dichlorophenol
2,4-dinitrophenol
2,4,6-trichlorophenol
Alachlor ESA
Diazinon
Disulfoton
Diuron
Fonofos
Linuron
Polonium-210
Prometon
RDX
Terbufos
122-66-7
95-48-7
120-83-2
51-28-5
88-06-2
NAC
333-41-5
298-04-4
330-54-1
944-22-9
330-55-2
13981-52-7
1610-18-0
121-82-4
13071-79-9
EPA 525.2 "
SPE/GC/MS b
SPE/GC/MS b
SPE/GC/MS b
SPE/GC/MS b
Reserved (To be determined)
EPA 525.2 d
EPA 525.2 d
SPE/HPLC/UV e
EPA 525.2 a
SPE/HPLC/UV e
Reserved (To be determined)
EPA 525.2 d
Reserved (To be determined)
EPA 525.2 d
Microbiological Contaminants
Aeromonas hydrophila
NAC
Reserved (To be determined)
a Contaminant currently not listed as analyte in this method. Methods under current development in an attempt to add this
contaminant to the scope of this method. See Table 3.1 for full method reference.
b Methods development currently in progress to develop a solid phase extraction/gas chromatography/mass spectrometry
(SPE/GC/MS) method for the determination of this compound.
c CASRN is Not Applicable.
d Contaminant listed to be analyzed with this method; however, adequate sample preservation for this contaminant is not provided
by the procedures for this method. Preservation studies are currently being developed for suitable sample preservation for this
contaminant.
e Methods development currently in progress to develop a solid phase extraction/high performance liquid chromatography/ultraviolet
(SPE/HPLC/UV) method for the determination of this compound.
3.2.1. List 2 Chemical Contaminants
1,2-diphenylhydrazine - No well-developed methods that could be implemented at reasonable costs were
identified for 1,2-diphenylhydrazine. The methods evaluated required large volume solvent extraction,
acid, base/neutral fractionation, and were developed for packed column chromatography. In addition, no
documentation of either aqueous or extract analyte stability was available. EPA has identified 1,2-
diphenylhydrazine as a priority for methods development. It is anticipated that 1,2-diphenylhydrazine will
be monitored with EPA Method 525.2 following the development of a modified analyte preservation
technique.
2-methyl-phenol - No we 11-developed methods that could be implemented at reasonable costs were
identified for 2-methyl-phenol. The methods evaluated required the use of large volume solvent extraction,
acid, base/neutral fractionation, and were developed for packed column chromatography. In addition, no
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Technical Background Information for the UCMR March 2000
documentation of either aqueous or extract analyte stability was available. EPA has identified 2-methyl-
phenol as a priority for analytical methods development. It is anticipated that 2-methyl-phenol will be
included in a new SPE/GC/MS method currently under development. Once this method is fully developed,
EPA will determine if the quality of data generated by this new method meets the needs of the regulation.
2,4-dichlorophenol - The only analytical method identified for 2,4-dichlorophenol that was well-devel-
oped and of reasonable cost was EPA Method 552. However, under the derivatization conditions specified
in this method, only 10 percent to 20 percent of the analyte is derivatized. Identification and quantification
is then made on the remaining underivatized analyte. EPA has determined that due to the quantitative
uncertainty that would result, this method would not produce data of sufficient quality to meet the objec-
tives of the UCMR. EPA has identified 2,4-dichlorophenol as a priority for analytical methods develop-
ment. It is anticipated that 2,4-dichlorophenol will be included in a new SPE/GC/MS method currently
under development. Once this method is fully developed, EPA will determine if the quality of data gener-
ated by this new method meets the needs of the regulation.
2,4-dinitrophenol - No well-developed methods that could be implemented at reasonable costs were
identified for 2,4-dinitrophenol. The methods evaluated required the use of large volume solvent extrac-
tion, acid, base/neutral fractionation, and were developed for packed column chromatography. In addition,
no documentation of either aqueous or extract analyte stability was available. EPA has identified 2,4-
dinitrophenol as a priority for analytical methods development. It is anticipated that 2,4-dinitrophenol will
be included in a new SPE/GC/MS method currently under development. Once this method is fully devel-
oped, EPA will determine if the quality of data generated by this new method meets the needs of the
regulation.
2,4,6-trichlorophenol - EPA Method 552 is the only analytical method identified for 2,4,6-trichloro-
phenol which is well-developed and of reasonable cost. However, 2,4,6-trichlorophenol is subject to
interferences caused by the derivatization product of 2,4-dichlorophenol produced by this method. Due to
the need to minimize false positives, EPA determined that this method would not produce data of sufficient
quality to meet the objectives of the UCMR. EPA has identified 2,4,6-trichlorophenol as a priority for
analytical methods development. It is anticipated that 2,4,6-trichlorophenol will be included in a new SPE/
GC/MS method currently under development. Once this method is fully developed, EPA will determine if
the quality of data generated by this new method meets the needs of the regulation.
Alachlor Ethane Sulfonic Acid (Alachlor ESA) and other degradation products of acetanilide pesti-
cides - EPA is actively evaluating what specific analytes are to be included with this group of compounds.
Following the completion of this evaluation, EPA will determine whether analytical methods for the
determination of specific compounds are available, if methods development is necessary, or if determina-
tion by chemical class would provide the best data.
Diazinon - While diazinon is listed as an analyte in EPA Methods 507, EPA Method 525.2, and several
voluntary consensus standards, because of its extremely rapid aqueous degradation, accurate and precise
measurement of stored samples is not achieved. Preservation studies conducted during the development of
EPA Method 525.2 determined that no diazinon could be detected after 7 days of refrigerated storage of
samples spiked with 5.0 (ig/L diazinon. EPA has identified diazinon as a priority for analytical methods
development. Specifically, EPA is currently conducting research to develop preservation techniques that
would permit the use of EPA Method 525.2 for monitoring diazinon. Once these techniques are fully
developed, it is anticipated that diazinon will be monitored with EPA Method 525.2.
Disulfoton - While disulfoton is listed as an analyte in EPA Methods 507, EPA Method 525.2, and
several voluntary consensus standards, because of its extremely rapid aqueous degradation, accurate and
precise measurement of stored samples is not achieved. Preservation studies conducted during the develop-
ment of EPA Method 525.2 determined that only 1.2 (ig/L of disulfoton could be detected after 7 days of
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Technical Background Information for the UCMR March 2000
refrigerated storage of samples spiked with 5.0 (jg/L, and only 0.7 (ig/L after 10 days of refrigerated
storage. Preservation studies conducted during the National Pesticide Survey (NPS) determined that less
than one percent of the disulfoton spiked into field samples remained after 14 days of refrigerated storage.
EPA has identified disulfoton as a priority for analytical methods development. Specifically, EPA is
currently conducting research to develop preservation techniques that would permit the use of EPA
Method 525.2 for monitoring disulfoton. Once these techniques are fully developed, it is anticipated that
disulfoton will be monitored with EPA Method 525.2.
Diuron - Both EPA Method 553 and NPS Method 4 can be used to accurately determine the quantitative
concentration of Diuron in drinking water, however, neither method is suitable for the routine analyses
required under this regulation. EPA Method 553 is a 1 liter LLE or SPE/high performance liquid chroma-
tography/particle beam/mass spectrometry method (LLE or SPE/HPLC/PB/MS). As particle beam
devices are no longer produced, the excessive costs associated with PB/MS methods prohibit their use on a
national scale. NPS Method 4 is a 1 liter LLE/HPLC/UV method. However, NPS Method 4 is somewhat
cumbersome, and the sensitivity achieved with the method would not be optimal for its use under this
regulation. EPA has identified Diuron as a priority for analytical methods development. Determination by
HPLC/UV of extracts generated using SPE techniques should be feasible, and it is anticipated that Diuron
will be included in a new SPE/HPLC/UV method currently under development. Once this method is fully
developed, EPA will determine if the quality of data generated by this new method meets the needs of the
regulation.
Fonofos - No well-developed methods that could be implemented at reasonable costs were identified for
fonofos. Fonofos was evaluated for possible inclusion in EPA Method 507, however, because of its severe
aqueous instability, it was not included in the final method. Other EPA and voluntary consensus organiza-
tion methods list fonofos as an analyte, but experience the same problems with aqueous instability. Preser-
vation studies conducted during the development of EPA Method 507 determined that no fonofos could be
detected after 7 days of refrigerated storage of samples spiked with 6.5 (ig/L. EPA has identified fonofos
as a priority for analytical methods development. Specifically, EPA is currently conducting research to
develop preservation techniques that would permit the use of EPA Method 525.2 for monitoring fonofos.
Once these techniques are fully developed, it is anticipated that fonofos will be monitored with EPA
Method 525.2.
Linuron - Both EPA Method 553 and NPS Method 4 can be used to accurately determine the quantitative
concentration of linuron in drinking water, however, neither method is suitable for the routine analyses
required under this regulation. EPA Method 553 is a 1 liter LLE or SPE HPLC/PB/MS method. As
particle beam devices are no longer produced, the excessive costs associated with PB/MS methods prohibit
their use on a national scale. NPS Method 4 is a 1 liter LLE/HPLC/UV method. However, NPS Method 4
is somewhat cumbersome, and the sensitivity achieved with the method would not be optimal for its use
under this regulation. EPA has identified Linuron as a priority for analytical methods development.
Determination by HPLC/UV of extracts generated using SPE techniques should be feasible, and it is
anticipated that Linuron will be included in a new SPE/HPLC/UV method currently under development.
Once this method is fully developed, EPA will determine if the quality of data generated by this new
method meets the needs of the regulation.
Polonium-210 - Information on the availability of analytical methods for monitoring polonium-210 under
the UCMR is limited at the present time. As noted in previous sections of this document, EPA did not
initially propose to include polonium-210 on the UCMR (1999) List. EPA is currently evaluating methods
for detecting polonium-210 in water samples, but an appropriate method may be very time consuming and
will likely require an experienced analyst. There are also significant laboratory capacity and capability
concerns. Few, if any, laboratories currently performing compliance drinking water radiochemistry have
any experience with polonium-210. EPA will provide additional information on appropriate analytical
methods when this information becomes available.
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Technical Background Information for the UCMR March 2000
Prometon - EPA Method 507, EPA Method 525.2, and several voluntary consensus standards could be
used to accurately determine the quantitative concentration of prometon in drinking water. EPA Method
507 is a 1 liter LLE/GC/NPD method. However, analyte preservation studies conducted during the
development of EPA Method 507 demonstrate aqueous instability of spiked reagent water samples. Only
60 percent recovery of prometon was observed in stored spiked reagent water samples on the day they
were spiked, 21 percent after 14 days of refrigerated storage, and 11 percent after 28 days of refrigerated
storage. In contrast, preservation studies conducted on spiked field samples during the NPS demonstrated
excellent stability, with 95 percent recovery after 14 days of refrigerated storage. These data seem to
indicate that prometon undergoes significant base-catalyzed hydrolysis, as the spiked field samples col-
lected during the NPS were naturally buffered, whereas the spiked reagent water samples analyzed during
the development of EPA Method 507 were not buffered. In addition, acidified stored samples analyzed
during preservation studies conducted during the development of EPA Method 525.2 demonstrated analyte
stability within the precision of the determination. Unfortunately, analyte recovery was less than 50
percent. EPA Method 525.2 is a SPE/GC/MS method forthe determination of abroad range of organics
which requires that samples be acidified upon collection. This required acidification resulted in the proto-
nation of prometon's nitrogen atoms, which in turn resulted in poor recovery. Because prometon is un-
stable in neutral to basic samples, but is not well extracted from acidified samples, a separate, acidified
sample, which will be neutralized in the laboratory immediately prior to extraction, should be collected for
the analysis of prometon. Neither method has been verified forthe determination of prometon using sample
neutralization in the laboratory. EPA has identified prometon as a priority for analytical methods develop-
ment. Specifically, EPA is currently conducting research into neutralizing the pH just prior to extraction,
which would permit the use of EPA Method 525.2 for monitoring prometon. Once these techniques are
fully developed, it is anticipated that prometon will be monitored with EPA Method 525.2.
RDX - Information on the availability of analytical methods for monitoring RDX under the UCMR is
limited at the present time. As noted in previous sections of this document, EPA did not initially propose to
include RDX on the UCMR (1999) List. During the peer review conducted forthe UCMR, a reviewer
identified EPA Method 8330 contained in SW-846 as a method that has been used to measure RDX.
However, the reviewer also noted that this method can be difficult, and EPA feels it may be inappropriate
for drinking water analyses under the UCMR. EPA will provide additional information on appropriate
analytical methods when this information becomes available.
Terbufos - While terbufos is listed as an analyte in EPA Methods 507, EPA Method 525.2, and several
voluntary consensus standards, because of its extremely rapid aqueous degradation, accurate and precise
measurement of stored samples is not achieved. Preservation studies conducted during the development of
EPA Method 525.2 determined that only 2.3 (ig/L of terbufos could be detected after 10 days of refriger-
ated storage of samples spiked with 5.0 (ig/L. Preservation studies conducted during the NPS determined
that less than one percent of the terbufos spiked into field samples remained after 14 days of refrigerated
storage. EPA has identified terbufos as a priority for analytical methods development. Specifically, EPA is
currently conducting research to develop preservation techniques that would permit the use of EPA
Method 525.2 for monitoring terbufos. Once these techniques are fully developed, it is anticipated that
fonofos will be monitored with EPA Method 525.2.
3.2.2. List 2 Microbiological Contaminants
Aeromonas hydrophila (sensu lata) - This group or complex of aeromonads are distinguishable genotypi-
cally by DNA-DNA hybridization, but difficult or impossible to distinguish phenotypically by using
physiological reactions commonly applied for the identification of bacteria. However, a published mem-
brane filtration method (Havelaar et al, 1987) has been evaluated for use, and with minor modifications,
should be suitable for use in the Screening Surveys. Few published studies have compared isolation and
enumeration methods, and the sensitivity and detection limits of this method have not been fully deter-
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Technical Background Information for the UCMR
March 2000
mined. The reliability of the method is dependent upon the experience of the investigator, sample turbidity,
and the number and kind of competing bacteria present in the sample, as no proficiency testing program is
available at this time.
3.3. List 3 Contaminants
All contaminants not included on Lists 1 or 2 of the UCMR List are included on List 3. List 3
contaminants are those for which EPA has begun or shortly will begin analytical methods development,
but completion of those efforts is not expected prior to the Assessment Monitoring or Screening Surveys
required under the initial implementation of the UCMR. Instead, these contaminants may be monitored
during the Pre-Screen Testing component of the UCMR Program, most likely to be conducted in 2004. At
this time, there are seven microbiological contaminants and one chemical contaminant on List 3 of the
UCMR (1999) List.
3.3.1. List 3 Chemical Contaminants
Table 3.3 Possible Analytical Methods for UCMR (1999) List 3 Contaminants
Contaminant
CASRN
Possible Analytical Methods
Chemical Contaminants
Lead-210
14255-04-0
Reserved (To be determined)
Microbiological Contaminants
Ad enovi ruses
Cyanobacteria (Blue-Green Algae), other
Freshwater Algae, and their Toxins
Calicivi ruses
Coxsackievi ruses
Echovi ruses
Helicobacter pylori
Microsporidia
Not applicable
Not applicable
Not applicable
Not applicable
Not applicable
Not applicable
Not applicable
Reserved (To be determined)
Reserved (To be determined)
Reserved (To be determined)
Reserved (To be determined)
Reserved (To be determined)
Reserved (To be determined)
Reserved (To be determined)
Lead-210 - Information on the availability of analytical methods for monitoring lead-210 under the
UCMR is limited at the present time. As noted in previous sections of this document, EPA did not initially
propose to include lead-210 on the UCMR (1999) List. EPA is currently evaluating methods for detecting
lead-210 in water samples, but an appropriate method may be very time consuming and will likely require
an experienced analyst. There are also significant laboratory capacity and capability concerns. Few, if any,
laboratories currently performing compliance drinking water radiochemistry have any experience with
lead-210. EPA will provide additional information on appropriate analytical methods when this informa-
tion becomes available.
3.3.2. List 3 Microbiological Contaminants
The status of analytical methods availability for the seven microbiological contaminants included
on List 3 is highly dependent on the specific organisms that are to be targeted for monitoring. For ex-
ample, some of the coxsackieviruses and echoviruses grow in tissue culture assays and are detected with
the ICR method (USEPA 1996), although other members of these groups may not be detected. Before
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Technical Background Information for the UCMR March 2000
monitoring can begin, the specific organisms must be identified, as partial assays of these organisms might
not be useful and might overlook important pathogenic serotypes.
A fundamental issue with method development for all microorganisms is viability. Viable organ-
isms, and particularly those that are infective, are usually the only organisms of concern. While culture
methods only count viable organisms, not all of the List 3 microorganisms can presently be cultured, and
in the case of the viruses, available culture methods can be very expensive. In addition, different cell
culture lines would be required to assay for different viruses, which would multiply costs. In some cases,
such as some of the group A coxsackieviruses or the caliciviruses, it may not be possible to develop a
culture method. Although potentially less expensive and faster, polymerase chain reaction (PCR) tech-
niques may assay nonviable or even lysed organisms, and are subject to interferences from foreign DNA
or inhibiting substances.
All List 3 microbiological contaminants have been identified as needing analytical methods
development before occurrence data can be collected. Although clinical detection methods might exist for
these organisms, these methods often are incapable of detecting organisms in environmental water
samples. Thus, standard EPA methods do not currently exist for these contaminants, and in many cases the
development of an assay method will be difficult. Although EPA anticipates having sufficient analytical
methods available for these organisms in time for the Pre-Screen Testing component of the UCMR Pro-
gram in 2003, it should be realized that even after three years of research, method development for some
of these microorganisms may not have proceeded to a point where work can begin on determining con-
taminant occurrence as a prelude to making a regulatory decision. A partial review of potential analytical
methods for each contaminant is included below. For a more detailed review of potential analytical meth-
ods for the UCMR (1999) List 3 microbiological contaminants, please refer to the draft report entitled
Methods and Occurrence Information for the UCMR List 3 Microbiological Contaminants, available
from Rachel Sakata of US EPA's Office of Ground Water and Drinking Water.
Adenoviruses - Serotypes 1-39 can be grown in tissue cultures, but the enteric adenoviruses, serotypes 40
and 41, have been difficult to grow. Information on and analytical methods for serotypes 42-49 is very
limited due the fact that they have only recently been isolated. While several selective tissue culture
methods and detection methods have been reported, a selective, standardized method is needed for monitor-
ing. Several cell lines will support the growth of the enteric adenoviruses, although these cell lines have
not been evaluated to determine how well they work in assays of water samples. Tissue culture assays
would be very expensive and would limit the size of any monitoring that was done for these viruses. Cell
lines used forthe adenoviruses could be different from those used for other viruses. As discussed above,
PCR-based methods are not preferred because of interferences and their inability to demonstrate infectiv-
ity.
Cyanobacteria (Blue-Green Algae), other Freshwater Algae, and their Toxins - While EPA methods
are available for counting cyanobacteria, new, standardized methods are needed for direct counts of
targeted species with filtration methods or a counting chamber. Targeting individual species is essential, as
microscopic examination may not be able to distinguish algae that do and do not produce toxins. Although
methods have been described for both the alkaloid neurotoxins and the cyclic polypeptide hepatotoxins, no
standard methods exist for detecting algal toxins. Once developed, these methods may require costly
equipment. A layered approach might be considered forthe analyses of algal toxins. This approach could
start with screening methods and progress to instrumental analyses and toxicity assays.
Caliciviruses - Two genogroups of human caliciviruses, genogroup I (Norwalk and Norwalk-like viruses)
and genogroup II (Snow Mountain and Snow Mountain-like viruses), are of concern because of water-
borne outbreaks of gastrointestinal illness. Tissue culture assays have not been developed for these vi-
ruses, although some work is in progress. If a tissue culture assay is developed for these viruses, it would
have a high cost and would thus limit the size of the sample for the Pre-Screen Testing monitoring compo-
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Technical Background Information for the UCMR March 2000
nent. Such a method would most likely involve the use of a separate cell line not used for the other List 3
viruses. Because it would count only viable organisms, a tissue culture assay would be preferred. If it is
not possible to develop a tissue culture assay for these viruses, an alternative analytical method will have
to be used. However, no sensitive or fully developed detection methods currently exist. As discussed
above, PCR-based methods are not preferred because of interferences and their inability to demonstrate
infectivity.
Coxsackieviruses - Group B coxsackieviruses are easy to grow in tissue culture, but Group A cox-
sackieviruses are variable. Culturable coxsackieviruses can be detected with the ICR method, but sero-
typing is needed to distinguish coxsackie from other viruses. Individual serotypes can be identified by
typing with appropriate sera. Decisions will need to be made on exactly which individual or combinations
of serotypes will be monitored. As with many of the potential methods for List 3 contaminants, culture and
typing methods for detecting coxsackieviruses could be very expensive, and would thus limit the size of
the sample for the Pre-Screen Testing monitoring component. Other detection methods using techniques
such as immunoassays or PCR do not exist, and as discussed above, PCR-based methods are not preferred
because of interferences and their inability to demonstrate infectivity.
Echoviruses - With care to control overgrowths, echoviruses can be cultured on buffalo green monkey
(BGM) cells and detected by the ICR method, but methods are needed which include serological typing.
As with many of the potential methods for List 3 contaminants, culture and typing methods for detecting
echoviruses could be very expensive, and would thus limit the size of the sample for the Pre-Screen
Testing monitoring component. As discussed above, PCR-based methods, which are not currently avail-
able for echoviruses, are not preferred because of interferences and their inability to demonstrate infectiv-
ity.
Helicobacterpylori - A selective growth medium which suppresses background bacteria but allows H.
pylori to grow does not currently exist. Furthermore, this bacterium is difficult to grow because of slow
growth and the need for a low oxygen environment. A PCR-based method is available, but as discussed
above, PCR-based methods are not preferred because of interferences and their inability to demonstrate
infectivity. A culture method that demonstrates viability is preferred. Immunomagnetic separation (IMS)
has been used to concentrate Helicobacter pylori.
Microsporidia - The two groups of human microsporidia of interest for the UCMR, Enterocytozoon
bienuesi and Encephalitozoon (formerly Septata) intestinalis, do not have suitable analytical methods
available. A method capable of detecting oocysts, similar to EPA Method 1622 used for Giardia and
Cryptosporidium, could be developed for these protozoa. A filtration method will have to be developed for
the human microsporidia, since they are smaller than Giardia or Cryptosporidium and would not be
amenable to filtration with the filters used for EPA Method 1622 or the ICR method (USEPA 1996). Other
potential methods may utilize water filtration, clean-up with IMS, and detection using either microscopy,
fluorescent antibody, or gene probe techniques. Work is in progress on developing these techniques for
clinical applications and for the water industry.
3.4. References
Havelaar, A. H., M. During and J. F. Versteegh. 1987. Ampicillin-dextrin agar medium for the enumera-
tion of Aeromonas species in water by membrane filtration. Journal of Applied Bacteriology. 62(3):279-
287.
USEPA. 1996. ICRMicrobial Laboratory Manual. EPA Publication No. EPA/600/R-95/178, Cincinnati,
OH.
26
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Technical Background Information for the UCMR March 2000
Notes
^pon completion of methods development for List 2 and/or List 3 contaminants, EPA will
specify which methods are approved for monitoring these contaminants. However, it is anticipated that
only EPA-designated laboratories will be allowed to perform these analyses.
27
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28
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Section 4. Spatial Distribution
This section is intended to provide additional occurrence information on the 36 contaminants on
the UCMR (1999) List. In particular, this section provides a brief summary of the spatial patterns of use,
environmental release, and production of the 36 contaminants. This review is not exhaustive; it is designed
to provide an overview for consideration of possible monitoring scenarios.
4.1. Sources of Information
Various sources of information on the release, use, and potential use of contaminants were re-
viewed. This information, in its aggregate form, has been evaluated to estimate the occurrence or potential
for occurrence for the UCMR (1999) Lists 1, 2, and 3 contaminants. The primary sources of information
reviewed were: the Environmental Protection Agency's (EPA) Toxic Release Inventory (TRI) Database;
the United States Geological Survey (USGS) National Water Quality Assessment Pesticide program's
National Pesticide Synthesis Project; Larson, Capel, and Majewski, Pesticides in Surface Water, 1997;
and the 1992 US Census of Manufactures. Other background sources include Agency for Toxic Sub-
stances and Disease Registry (ATSDR) fact sheets and other studies. Most of the data are reported release
or application estimates. The Census data, however, only provide an idea as to where a compound might
be used, whether or not there is an actual release of the compound to the environment. Tables 4.1, 4.2, and
4.3 summarize the data sources and coverage for each compound, according to UCMR (1999) List
designation as well as the potential environmental sources for each contaminant. The tables summarize
occurrence patterns by EPA Region. Figures 4.1-4.14 show greater detail for select contaminants.
4.1.1. Toxic Release Inventory Database
EPA's TRI Database contains chemical release information from regulated facilities for more than
500 contaminants. Companies are required to report releases to the TRI if they meet three conditions: (1)
the company must have the equivalent often or more full-time employees; (2) the company must be a
manufacturing facility listed under the Standard Industrial Classification (SIC) codes 20 through 39 or
else be a metal or coal mining, electric generating, chemical wholesaler, petroleum bulk plant or terminal,
commercial hazardous waste treatment, or solvent recycling facility, and; (3) the company must manufac-
ture, import, or process more than 25,000 pounds per year of one or more listed chemicals or use more
than 10,000 pounds of listed chemicals. Since the release of contaminants by small businesses or non-
manufacturing industries that do not meet all three criteria goes unreported by TRI, occurrence of some
contaminants is likely more widespread than TRI data would indicate.
TRI contains data for 15 of the UCMR (1999) List 1 and 2 compounds. These compounds are
2,4-dinitrotoluene, 2,6-dinitrotoluene, methyl tertiary-butyl ether (MBTE), nitrobenzene, s-ethyl-dipro-
pylthio-carbamate (EPTC), molinate, terbacil, 1,2-diphenylhydrazine, 2-methyl-phenol (o-cresol), 2,4-
dinitrophenol, 2,4,6-trichlorophenol, 2,4-dichlorophenol, diazinon, diuron, and linuron.
4.1.2. USGS National Pesticide Synthesis Project
Information on most of the pesticide compounds on the UCMR (1999) Lists 1 and 2 was available
in the USGS National Water Quality Assessment program's Pesticide National Synthesis Project. The
Pesticide National Synthesis Project produced maps of estimated annual pesticide use by county for the
29
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Technical Background Information for the UCMR March 2000
conterminous United States. The maps are based on the National Center for Food and Agricultural Policy
(NCFAP) estimates of pesticide use rates derived from State and federal pesticide application surveys and
crop acreage data from the 1992 Census of Agriculture. The NCFAP estimated the average annual
application per treated acre of a crop for each compound and the percentage of cropland treated per State.
These coefficients were applied to county crop acreage from the 1992 Census of Agriculture to estimate
the amount of pesticide used per square mile by county. The NCFAP estimates do not include pesticide
applications to non-cropland (such as private residential use or golf-course use) or pesticides applied to
pasture land not reported in the Census of Agriculture (such as federally owned pasture and grazing land).
In addition, because of Census non-disclosure rules, the 1992 Census of Agriculture might not report all
crop acreage in a county when the acreage is small or restricted to very few owners.
USGS map data are available for acetochlor, diazinon, disulfoton, diuron, EPTC, fonofos,
linuron, molinate, terbacil, and terbufos. For regional data on the distribution of alachlor ESA, DCPA di-
acid degradate, and DCPA mono-acid degradate, the parent compounds alachlor and DCPA are used as
proxies. The USGS maps used for this study are included as Figures 4.1 - 4.4 and 4.7 - 4.14.
A report generated by the USGS Pesticide National Synthesis Project provides information on
general occurrence of pesticides in ground water from the National Water Quality Assessment Program
(NAWQA) (Kolpin etal, 1998). This report provides insight on the herbicide prometon, which was not
included in the other data.
4.1.3. Census Data
In cases where other data were lacking, the 1992 Census of Manufactures was used to provide
potential compound occurrence information based on presumed usage. While a contaminant might be
associated with a given SIC industry, it cannot be assumed, and probably is unlikely, that every facility in
the SIC category actually uses that compound. In addition, a few facilities across a wide variety of SIC
categories might use a given compound, even if 90 percent or more of the compound's use is concentrated
within one SIC industry. In any event, for most UCMR compounds it is difficult to pinpoint a single or
small group of industries which adequately represent usage of a contaminant. Thus, the Census SIC data
may be the least reliable indicator of potential occurrence. Census of Manufacturing data was used for
only one contaminant, Royal Demolition eXplosive (RDX or l,3,5-trinitro-l,3,5-triazine).
4.1.4. Other Sources of Occurrence Information
Larson and colleagues (1997) provided pesticide coverage data for a number of UCMR (1999)
List 1 and 2 compounds, most of which overlap with USGS or TRI data. Data for alachlor (substituted for
alachlor ESA), diazinon, disulfoton, terbufos, EPTC, molinate, DDE, and prometon were included (maps
of distribution were available for all these compounds except DDE and prometon).
The report Perchlorate Environmental Contamination: Toxicological Review and Risk Charac-
terization Based on Emerging Information, 1998, contains information on perchlorate releases nation-
wide. This draft EPA report is still under review. Figures 4.5 and 4.6 are two maps related to perchlorate
production and occurrence reproduced from this report.
Often, more than one source of information was available for a contaminant. To provide the most
complete picture of occurrence, all overlapping sources of data for a compound were aggregated. As
noted, this report presents a brief summary of the geographic distribution from select major information
sources. In most cases these data are not entirely comprehensive. If all sites of production, release, use,
and transportation could be characterized, the geographic range for most contaminants would be increased
from that summarized here.
30
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Technical Background Information for the UCMR March 2000
4.2. Findings
Tables 4.1, 4.2, and 4.3 present regional occurrence patterns for UCMR (1999) Lists 1, 2, and 3
contaminants, respectively. Maps which summarize use, application, and distribution of many pesticides
and perchlorate are included as Figures 4.1-4.14.
4.2.1. UCMR (1999) List 1 Contaminants
There are 12 chemical contaminants on List 1 of the UCMR (1999) List. List 1 contaminants are
found in all ten EPA Regions. Four contaminants, DCPA di-acid degradate, DCPA mono-acid degradate,
EPTC, and MTBE are used or found in all EPA Regions. Every List 1 chemical contaminant except
acetochlor is used in Regions 4 and 6 and every contaminant except molinate is used in Region 3. The
fewest List 1 contaminants are found in Region 1, where only 6 of the 12 compounds appear in the data.
For the 12 contaminants, only 3 are not reported as occurring in seven or more EPA Regions. Nine
contaminants appear in at least seven EPA Regions. Molinate exhibits the most restricted geographic use
area of any UCMR contaminant, restricted to the rice growing areas of the lower Mississippi River Valley,
the Gulf Coast, and California.
2,4-dinitrotoluene (2,4-DNT) is used in the production of isocyanate and explosives. 2,4-DNT appears in
the TRI database in EPA Regions 2, 3, 4, 5, 6, 7, and 9.
2,6-dinitrotoluene (2,6-DNT) has similar uses to 2,4-DNT and the two are often used as a mixture.
Although 2,6-DNT is listed in the TRI database only for Regions 3, 4, 6, and 9, it may actually used be
more widely in conjunction with 2,4-DNT. It is probable that its potential occurrence is more widespread
than the TRI data would indicate.
Acetochlor is an herbicide used on corn, cabbage, citrus, and coffee crops. Acetochlor appears on Na-
tional Pesticide Synthesis Project maps in Regions 3, 5, 7, 8, and 10 (these regions may not include all
production and transport areas). Its use may be expanding, however, as it only received registration for
corn in 1993. (See Figure 4.1)
DCPA di-acid degradate and DCPA mono-acid degradate are degradation products of DCPA (dimethyl
tetrachloroterephthalate, chemical name of the herbicide dacthal), an herbicide used on fruit and vegetable
crops to control grasses and weeds. These compounds are expected to be associated with the use of
DCPA; thus DCPA is taken as a proxy to estimate potential occurrence of the degradates. DCPA appears
in the National Pesticide Synthesis Project in all ten EPA Regions. (See Figure 4.2)
DDE (dichloro dichlorophenyl ethylene) is a degradation product of DDT (dichloro diphenyl trichloro-
ethane), a general-use insecticide banned in 1972. Larson and colleagues (1997) discuss detections of
DDE in surface waters in EPA Regions 2, 3, 4, 5, 6, 7, 8, 9, and 10.
EPTC (s-ethyl-dipropylthio-carbamate) is an herbicide used on corn and potatoes to control grasses and
weeds. EPTC is listed in all ten EPA Regions in the National Pesticide Synthesis Project maps. (See
Figure 4.3)
Molinate exhibits the most geographically restricted usage pattern of the UCMR (1999) List 1 contami-
nants. This is not surprising: it is used as a pesticide on rice crops to control water grass, mostly along the
lower Mississippi River Valley and Gulf Coastal Plain and in California. TRI data shows molinate re-
leases in EPA Regions 4, 6, and 9, while National Pesticide Synthesis Project maps place molinate use in
Region 7 as well. Molinate has been detected in 27 percent of targeted surface water sites in the Lower
Mississippi Valley and California (Larson et al., 1997). Molinate was only found in regions where rice is
grown. (See Figure 4.4)
31
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Technical Background Information for the UCMR
March 2000
Table 4.1. UCMR (1999) List 1 Contaminant Occurrence or Use by EPA Region
UCMR (1999) List 1 Contaminants
Contaminant
2,4-Dinitrotoluene
2,6-Dinitrotoluene
Acetochlor
DCPA di-acid
degradate (DCPA
used as a proxy for
this compound)
DCPA mono-acid
degradate (DCPA
used as a proxy for
this compound)
DDE
EPIC
Molinate
MTBE
Nitrobenzene
Perchlorate
Terbacil
Potential
Environmental
Source
Used in the production of
isocyanate and explosives
Used as mixture with 2,4-
DNT (similar uses)
Herbicide used on corn,
cabbage, citrus, and coffee
Degradation product of
DCPA, an herbicide used
on grasses and weeds with
fruit and vegetable crops
Degradation product of
DCPA, an herbicide used
on grasses and weeds with
fruit and vegetable crops
Degradation product of
DDT; a general insecticide
Herbicide used on grasses
and weeds, with potatoes
and corn
Selective herbicide used
on rice; controls watergrass
Octane enhancer in
unleaded gasoline
Used in the production of
aniline, which is used to
make dyes, herbicides,
and drugs; also used as a
solvent in paint and shoe,
floor, and metal polishes.
Oxygen additive in solid
fuel propellant for rockets,
missiles, and fireworks
Herbicide used on
sugarcane, alfalfa, fruit, etc.
EPA Regions
1
-
-
-
B
B
-
B,C
-
A
A
-
B
2
A
-
-
B
B
C
B,C
-
A
A
E
B
3
A
A
B
B
B
C
B,C
-
A
A
E
B
4
A
A
-
B
B
C
A,B,C
A,B,C
A
A
E
A,B
5
A
-
B
B
B
C
B,C
-
A
A
E
B
6
A
A
-
B
B
C
A,B,C
A,B,C
A
A
E
A,B
7
A
-
B
B
B
C
A,B,C
B,C
A
A
E
-
8
-
-
B
B
B
C
B,C
-
A
-
E
B
9
A
A
-
B
B
C
B,C
A,B,C
A
-
E
-
10
-
-
B
B
B
C
B,C
-
A
-
E
B
No letter entry in a table cell signifies that there is no information in the sources reviewed regarding occurrence or use of a
contaminant in a region. Sources are listed below.
A: TRI database
B: USGS National Pesticide Synthesis Project (see Figure 4.1-4.14)
C: Larson, Capel, and Majewski, Pesticides in Surface Water, 1997
D: 1992 US Census of Manufactures
E: Perchlorate Environmental Contamination
32
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Technical Background Information for the UCMR
March 2000
ACETOCHLOR
ESTIMATED ANNUAL AGRICULTURAL USE
Average use of
Active Ingredient
Pounds per square mile
of county per year
U No Estimated Use
D <2.789
• 2.769-14.926
D 14,927-47.816
D 47.617-96.419
• >= 96.420
Cropo
Total
Pounds Appled
Percent
National Usa
UUII
23,84-1,036
100.00
Figure 4.1. Acetochlor—Estimated Annual Agricultural Use. National Pesticide Synthesis Project. Maps of Annual
Pesticide Use, 1992. United States Geological Survey. National Water Quality Assessment Pesticide Program.
Available on internet at http://water.wr.usgs.gov/pnsp/use92/.
33
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Technical Background Information for the UCMR
March 2000
DCPA
ESTIMATED ANNUAL AGRICULTURAL USE
Average use of
Active Ingredient
Pounds per square mile
of county per year
LJ No Estimated Use
D <0.006
D 0.008-0.016
D 0.019-0.057
D 0.068-0.2B9
• >= 0.290
Total
Crop* Pounds Applad
oriora
brocool
Held and green and
cabtafjB
hot poppon
cauliflower
sod
swa at potatoes
colbrda
aquaah
27^506
me, 394
11&.4B6
BI.416
SB, 086
53,357
40,778
33,146
22, 4«
19, 8M
Peroent
NattonalUaa
Z7.5E
22.69
11.68
a ie
6.62
5.35
4,00
aaa
2. a
1.99
Figure 4.2. DCPA—Estimated Annual Agricultural Use. National Pesticide Synthesis Project. Maps of Annual
Pesticide Use, 1992. United States Geological Survey. National Water Quality Assessment Pesticide Program.
Available on internet at http://water.wr.usgs.gov/pnsp/use92/.
34
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Technical Background Information for the UCMR
March 2000
EPTC
ESTIMATED ANNUAL AGRICULTURAL USE
Average use of
Active Ingredient
Pounds per square mile
ofcotkityporyear
D No Estimated Use
D < 0.099
D 0.099- 0.509
D 0.510-2.633
D 2.634-15,662
• >= 15.883
Crape
csm
dry beans
- . . j—|.| ..•
pDQnOW
alfalfa tay
•ugar bwto tor atqar
green beans
sweet com
tomatoes
field esidgrwa seed
BflrnQwer
Total
Pounds Applet!
9,102,979
1,403, 879
1,313,836
1,101,649
425,001
300,475
230,464
50,042
37,034
35,000
Percent
NettoneJUae
64.57
9.96
9.3E
a 2+
101
2.13
1.30
0.36
0.2B
a 25
Figure 4.3. EPTC—Estimated Annual Agricultural Use. National Pesticide Synthesis Project. Maps of Annual
Pesticide Use, 1992. United States Geological Survey. National Water Quality Assessment Pesticide Program.
Available on internet at http://water.wr.usgs.gov/pnsp/use92/.
35
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Technical Background Information for the UCMR
March 2000
MOLINATE
ESTIMATED ANNUAL AGRICULTURAL USE
Average use of
Active Ingredient
Pounds per square mile
of county par year
D No Estimated Use
D <4,B24
D 4,824-15.116
D 15.117-43.254
D 43.266-90.979
• >= 90.980
Crops
Total
Pounds Appled
Percent
NBtbnaJUsB
Doe
100.00
Figure 4.4. Molinate—Estimated Annual Agricultural Use. National Pesticide Synthesis Project. Maps of Annual
Pesticide Use, 1992. United States Geological Survey. National Water Quality Assessment Pesticide Program.
Available on internet at http://water.wr.usgs.gov/pnsp/use92/.
36
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Technical Background Information for the UCMR
March 2000
PERCHLORATE
CONFIRMED MANUFACTURERS OR USERS
Confirmed by EPA
Other Information
No Known Releases
Figure 4.5. Perchlorate—Confirmed Manufacturers or Users. States indicated as having confirmed perchlorate
manufacturers or users (hatch marks) are based on EPA Information Request responses from current manufac-
turers (identifying shipments of at least 500 pounds in any year). States noted by shading resulted from database
searches for types of facilities where releases have occurred in California (rocket manufacturing and testing
explosives manufacturing). No facilities have been identified in Alaska, Hawaii, Maine, Vermont, Connecticut, or
Rhode Island. Adapted from: United States Environmental Agency Office of Research and Development. Perchlo-
rate Environmental Contamination: Toxicological Review and Risk Characterization Based on Emerging Informa-
tion. NCEA-1-0503. December 31, 1998. External Review Draft.
37
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Technical Background Information for the UCMR
March 2000
PERCHLORATE
CONFIRMED RELEASES
Confirmed by EPA
Other Information
No Known Releases
Figure 4.6. Perchlorate—Confirmed Releases. States with confirmed release (hatch marks), in which facilities
have directly measured perchlorate in groundwater or surface water. Perchlorate measured in water in West
Virginia for a confidential client has been reported at a public conference but has not been confirmed indepen-
dently by EPA. Monitoring for perchlorate releases in most states is very limited or nonexistent. Adapted from:
United States Environmental Agency Office of Research and Development. Perchlorate Environmental Contami-
nation: Toxicological Review and Risk Characterization Based on Emerging Information. NCEA-1-0503. December
31, 1998. External Review Draft.
38
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Technical Background Information for the UCMR
March 2000
TERBACIL
ESTIMATED ANNUAL AGRICULTURAL USE
Average use of
Active Ingredient
Pounds per square mile
of county per year
D No Estimated Use
D < 0.001
D 0.001 - 0.004
D 0.005-0.014
D 0.016- 0.072
• >= 0.073
Total
Crops Pounds Applad
mint
sugar earn: sugar & seed
aJWtahay
apple*
peachn
field and graaa aaad
ttuobenrtea
strawberries
aaparegua
pacana
1ZD,SBB
9,19
35,786
30,3*
19,180
8,020
S, 474
2,710
1,591
1,£42
Percent
National Uaa
42. 85
30.78
12.67
io.ee
€173
2.43
2.27
0.96
0.66
0.44
Figure 4.7. Terbacil—Estimated Annual Agricultural Use. National Pesticide Synthesis Project. Maps of Annual
Pesticide Use, 1992. United States Geological Survey. National Water Quality Assessment Pesticide Program.
Available on internet at http://water.wr.usgs.gov/pnsp/use92/.
39
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Technical Background Information for the UCMR
March 2000
Methyl tertiary-butyl ether (MTBE), an octane enhancer in unleaded gasoline, appears in the TRI
database in all ten EPA Regions. MTBE is also released to the environment through gasoline spills,
storage tank leaks, automobile use, and various other non-point sources.
Nitrobenzene is used mostly in the production of aniline, which is used to make dyes, herbicides, and
Pharmaceuticals. It is also used as a solvent in paint and shoe, metal, and floor polishes. Nitrobenzene
appears in the TRI data for Regions 1, 2, 3, 4, 5, 6, and 7.
Perchlorate, an oxygen additive in solid fuel propellant for rockets, missiles, and fireworks, is an emerg-
ing contaminant, so monitoring has not been of long duration nor widespread. A recent EPA report
(USEPA 1998) identifies facilities where perchlorate releases have occurred in every EPA Region. The
report also finds confirmed detections of perchlorate in ground water in EPA Regions 2, 3, 5, 6, 8, and 9.
(See Figures 4.5 and 4.6)
Terbacil is an herbicide used on sugarcane, alfalfa, and fruit crops. Terbacil was found in EPA Regions 1,
2, 3, 4, 5, 6, 8, and 10 in the National Pesticide Synthesis Project maps. (See Figure 4.7)
4.2.2. UCMR (1999) List 2 Contaminants
UCMR (1999) List 2 contaminants are found in every EPA Region. The greatest number of
contaminants are found to be used in Region 4, where 12 of the 16 List 2 compounds appear in the data.
The fewest contaminants appear in Region 10, where only seven List 2 contaminants were found. Only
one of the 16 List 2 contaminants (2,4,6-trichlorophenol) appears in fewer than seven EPA Regions. The
compound 1,2-diphenylhydrazine is listed in the TRI database but no releases are reported.
Table 4.2. UCMR (1999) List 2 Contaminant Occurrence or Use by EPA Region
UCMR (1999) List 2 Contaminants
Contaminant
Potential
Environmental
Source
EPA Region
1
2
3
4
5
6
7
8
9
10
Chemical Contaminants
1 ,2-Diphenylhydrazine
2-Methyl-phenol
2,4-Dinitro-phenol
2,4,6-Trichloro-phenol
2,4-Dichloro-phenol
Used in the production of
benzidine and anti-
inflammatory drugs
Released in automobile
and diesel exhaust, coal
tar and petroleum refining,
and wood pulping
Released from mines,
metal, petroleum, and dye
plants
By-product of fossil fuel
burning, used as
bactericide and wood/glue
preservative
Chemical intermediate in
herbicide production
This contaminant is listed in the TRI database, but there are no records of
releases.
A
-
-
-
A
A
-
A
A
A
-
A
A
A
A
A
A
-
-
A
A
A
-
A
A
-
-
A
-
-
A
-
A
-
-
A
-
-
-
-
Note: No letter entry in a table cell signifies that there is no information in the sources reviewed regarding occurrence or use of a
contaminant in a region. Sources are listed below.
A: Data from TRI database
B: Data from USGS National Pesticide Synthesis Project (see Figures 4.1-4.14)
C: Data from Larson et al., 1997.
D: Data from 1992 US Census of Manufactures
E: Data from Perchlorate Environmental Contamination
40
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Technical Background Information for the UCMR
March 2000
Table 4.2. UCMR (1999) List 2 Contaminant Occurrence or Use by EPA Region (Continued)
UCMR (1999) List 2 Contaminants
Contaminant
Potential
Environmental
Source
EPA Region
1
2
3
4
5
6
7
8
9
10
Chemical Contaminants
Alachlor ESA (alachlor
used as a proxy for
this compound)
Diazinon
Disulfoton
Diuron
Fonofos
Linuron
Prometon
Polonium-210
RDX
Terbufos
Degradation product of
alachlor, an herbicide
used on corn, bean,
peanut, and soybean
crops to control grasses
and weeds
Insecticide used on corn,
rice, fruit, and vineyards
Insecticide used on
cereal, cotton, tobacco,
and potato crops
Herbicide used on
grasses in orchards and
wheat crops
Soil insecticide used on
corn, peanuts, and
potatoes to control worms
and centipedes
Herbicide used on corn,
soybean, cotton, and
wheat crops
Non-agricultural herbicide
used on weeds and
grasses
part of the uranium decay
series; natural occurrence
due to atmospheric fall out
explosives, ammunition
plants
Insecticide used on corn,
sugar beet, and grain
sorghum crops
B,C
B
B,C
B
B
B
B,C
A,B,C
B,C
B
B
B
B,C
B,C
B,C
B
B
B
B,C
A,B,C
B,C
A,B
B
A,B
B,C
A,B,C
B,C
B
B
B
B,C
A,B,C
B,C
A,B
B
B
B,C
A,B,C
B,C
A,B
B
A,B
B,C
A,B,C
B,C
B
B
B
B,C
A,B,C
B,C
B
B
B
B,C
B,C
B,C
B
B
B
This contaminant is a widely used (primarily non-cropland) herbicide, which is
expected to occur in every EPA Region. There is no discharge data for this
contaminant. See text for details.
Expected to occur in all Regions.
D
-
D
B,C
D
B,C
D
B,C
D
B,C
D
B,C
D
B,C
-
B,C
D
-
-
B,C
Microbiological Contaminants
Aeromonas
hydrophila
Present in all freshwater
and brackish water
Expected to occur in all Regions.
Note: No letter entry in a table cell signifies that there is no information in the sources reviewed regarding occurrence or use of a
contaminant in a region. Sources are listed below.
A: Data from TRI database
B: Data from USGS National Pesticide Synthesis Project (see Figures 4.1-4.14)
C: Data from Larson et al., 1997.
D: Data from 1992 US Census of Manufactures
E: Data from Perchlorate Environmental Contamination
1,2-diphenylhydrazine is used in the production of benzidine and anti-inflammatory drugs. This com-
pound is a TRI required contaminant, but there are no recorded releases of 1,2-diphenylhydrazine in the
TRI data because it is no longer produced in the United States. 1,2-diphenylhydrazine exists in older
products and wastes and it may still be possible for releases of imported quantities to occur based on its
use in manufacturing pharmaceuticals. This contaminant has been discovered by the EPA in at least seven
sites on the National Priorities List (Toxicological Profile for 1,2-Diphenylhydrazine, 1990).
41
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Technical Background Information for the UCMR March 2000
2-methyl-phenol (o-cresol) is used in wood pulping, coal tar and petroleum refining, and is released in
diesel exhaust. The contaminant 2-methyl-phenol appears in EPA Regions 1, 2, 3, 4, 5, 6, 7, and 9 in the
TRI database.
2,4-dinitrophenol is used in dye and petroleum and metal refining plants and is released from mines. The
contaminant 2,4-dintrophenol appears in the TRI data in EPA Regions 2, 3, 4, and 6.
2,4,6-trichlorophenol is used as a bactericide and a preservative for wood and glue. It is also a by-
product of fossil fuel production. This compound is listed in the TRI database for EPA Regions 4 and 8.
2,4-dichlorophenol is a chemical intermediate used in herbicide production. It is listed in the TRI data-
base in EPA Regions 2, 3, 4, 5, 6, 7, and 9.
Alachlor ESA (alachlor ethane sulfonic acid) is a degradation product of alachlor, an herbicide used on
corn, bean, peanut, and soybean crops to control grasses and weeds. Alachlor ESA is an emerging con-
taminant, so monitoring has not been widespread or of long duration. Therefore, alachlor is used a proxy
to estimate potential occurrence. Alachlor is found in all ten EPA Regions on the National Pesticide
Synthesis Project maps. (See Figure 4.8)
Diazinon is an insecticide used on corn, rice, fruit crops, and vineyards. Diazinon appears on the National
Pesticide Synthesis Project maps in all ten EPA Regions. (See Figure 4.9)
Disulfoton is an insecticide used on cereal, cotton, tobacco, and potato crops. Disulfoton appears on the
National Pesticide Synthesis Project maps in all ten EPA Regions. (See Figure 4.10)
Diuron is an herbicide used on grasses in orchards and with wheat crops. Diuron is found on the National
Pesticide Synthesis Project maps in all ten EPA Regions. (See Figure 4.11)
Fonofos is a soil insecticide used on corn, peanuts, potatoes, and other crops to control worms and
centipedes. Fonofos appears on the National Pesticide Synthesis Project maps in all ten EPA Regions. (See
Figure 4.12)
Linuron is an herbicide used on corn, soybean, cotton, and wheat crops. Linuron is found on the National
Pesticide Synthesis Project maps in all ten EPA Regions. (See Figure 4.13)
Polonium-210 (Po-210) is an isotope in the uranium decay series along with lead-210, radium-226, and
radon-222. Polonium-210, with a half-life of 138 days, has been found in drinking water. EPA is aware of
the occurrence of this contaminant in shallow aquifers in Florida (Harada, etal, 1989; Upchurch, 1991),
and in at least two other states. In addition, polonium-210 is expected to occur naturally in essentially
every part of the country as atmospheric fallout.
Prometon is a generic non-agricultural herbicide used on weeds and grasses. Prometon is widely used on
residential and commercial properties alongside buildings, fences, and other areas. As prometon is prima-
rily a non-agricultural pesticide, there are no maps of usage for this contaminant. However, USGS moni-
toring provides perspective on occurrence. A USGS National Pesticide Synthesis Project report (Kolpin et
al, 1998) cited prometon detections in 14 percent of 1,034 urban and agricultural wells sampled across
the United States. Larson, Capel, and Majewski (1997) detected prometon in 27 percent of midwest urban
monitoring wells.
RDX (Royal Demolition eXplosive; l,3,5-trinitro-l,3,5-triazine) is commonly used in military ammuni-
tion plants (SIC code 3483). The U.S. Census of Manufacturers identifies these facilities in EPA Regions
1, 2, 3, 4, 5, 6, 7, and 9. RDX might also be released to the environment near arsenals, military bases, or
construction sites using explosives.
42
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Technical Background Information for the UCMR
March 2000
ALACHLOR
ESTIMATED ANNUAL AGRICULTURAL USE
Average use of
Active Ingredient
Pounds per square mile
oTcoikity per year
D No Estimated Use
D <0.415
D 0,415-2.458
U 2.457-9.988
D 9.989-29.196
• >=29.196
Grope
corn
soybeans
my hum
Bwootcom
dry beans
peanuts
ootton
sunflower
Total
Pounda Appled
13,802,747
3,852,395
1,69,017
607,232
333,333
122,871
B1, H7G
23,784
Percent
National Uae
6421
3166
7.13
1.96
1.31
0.48
0.24
0.00
Figure 4.8. Alachlor—Estimated Annual Agricultural Use. National Pesticide Synthesis Project. Maps of Annual
Pesticide Use, 1992. United States Geological Survey. National Water Quality Assessment Pesticide Program.
Available on internet at http://water.wr.usgs.gov/pnsp/use92/.
43
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Technical Background Information for the UCMR
March 2000
DIAZINON
ESTIMATED ANNUAL AGRICULTURAL USE
Average use of
Active Ingredient
Pounds per square mile
of county per year
D No Estimated Use
D 0.004
D 0.004-0.019
D 0.020-0.073
D 0,074-0.298
• >= 0.297
Crop*
almonds
pfcfTM
POOCH BB
vnhriutB
Htuoa
rectal nea
swBBtconi
tobacco
appte^
5 citrus
Total
Pounds Applad
3ffi,037
153,99
134,986
73,542
73,301
07.1B4
87,027
55, §19
52,409
48.215
Percent
National UBA
19.93
9L62
a 35
4.66
4,64
4. 1fl
4,15
3.44
3-9
2.68
Figure 4.9. Diazinon—Estimated Annual Agricultural Use. National Pesticide Synthesis Project. Maps of Annual
Pesticide Use, 1992. United States Geological Survey. National Water Quality Assessment Pesticide Program.
Available on internet at http://water.wr.usgs.gov/pnsp/use92/.
44
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Technical Background Information for the UCMR
March 2000
DISULFOTON
ESTIMATED ANNUAL AGRICULTURAL USE
Average use of
Active Ingredient
Pounds per square mile
of county per year
U No Estimated Use
D < 0.017
D 0.017-0.144
D 0.145-0.605
D 0.908-1.832
• >= 1.833
Crops
cotton
wheat and grains
corn
potatoes
peanuta
sorghum
tobacco
aBfiaroffjo
SKy
bttyce
Total
Pounds Applet!
496,266
47BPBS7
303,334
184, 4tt
113,606
92,029
54,341
3B,77D
22,633
10,479
Parwnt
National Uaa
Z7.61
26.42
11.32
10. EG
a 33
5L11
a 02
2.15
1-«
oae
Figure 4.10. Disulfoton—Estimated Annual Agricultural Use. National Pesticide Synthesis Project. Maps of
Annual Pesticide Use, 1992. United States Geological Survey. National Water Quality Assessment Pesticide
Program. Available on internet at http://water.wr.usgs.gov/pnsp/use92/.
45
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Technical Background Information for the UCMR
March 2000
DIURON
ESTIMATED ANNUAL AGRICULTURAL USE
Average use of
Active Ingredient
Pounds per square mile
of county per year
D No Estimated Use
D < 0.010
D 0.010-0.050
D 0,051-0.255
D 0.268-1.378
• >= 1.378
Grope
alottrus
wheat and grains
cotton
field and gnm wsd
alfalfa hay
%&*£
other hay
•IfJfl'rMV
vwhuta
Total
Pounds Appled
1,083,503
777, SOB
742,308
436,287
101, 1SS
74, OH
84,429
84,273
33,017
Percent
NatlonaJUae
29.00
20.76
18. B1
11.70
5.68
2. TO
1.98
1.72
1.72
088
Figure 4.11. Diuron—Estimated Annual Agricultural Use. National Pesticide Synthesis Project. Maps of Annual
Pesticide Use, 1992. United States Geological Survey. National Water Quality Assessment Pesticide Program.
Available on internet at http://water.wr.usgs.gov/pnsp/use92/.
46
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Technical Background Information for the UCMR
March 2000
FONOFOS
ESTIMATED ANNUAL AGRICULTURAL USE
Average use of
Active Ingredient
Pounds per square mile
or county per year
D No Estimated Use
OL041- 0.291
a292- 1.524
1.625-4.704
>= 4.705
Cropa
com
peanuts
potatoes
mint
0WBBt pOtHtDM
sweat com
green beans
sugar baeta for sugar
tobacco
RBparBQu9
Total
Pounds Applad
2,182,035
289,69
33,102
B2,eae
S8.2B2
29,505
1i,Q73
17,201
12,863
10,847
Percent
National Uaa
77.61
10130
3113
2.24
2.07
1.06
an
a 6i
a«
O3B
Figure 4.12. Fonofos—Estimated Annual Agricultural Use. National Pesticide Synthesis Project. Maps of Annual
Pesticide Use, 1992. United States Geological Survey. National Water Quality Assessment Pesticide Program.
Available on internet at http://water.wr.usgs.gov/pnsp/use92/.
47
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Technical Background Information for the UCMR
March 2000
LINURON
ESTIMATED ANNUAL AGRICULTURAL USE
Average use of
Active Ingredient
Pounds per square mile
of county per year
D No Estimated Use
0.049-0.234
0,235-0.775
0.77B- 3.324
>= 3.325
Grope
soybeans
cotton
pcArtosw
CHTCto
euparaguH
celery
Total
Pounds Applad
1,673,458
21 6, 174
93,330
73,586
14.116
4,155
Percent
National (Joe
79.68
10.96
4.73
3173
0.71
0.21
Figure 4.13. Linuron—Estimated Annual Agricultural Use. National Pesticide Synthesis Project. Maps of Annual
Pesticide Use, 1992. United States Geological Survey. National Water Quality Assessment Pesticide Program.
Available on internet at http://water.wr.usgs.gov/pnsp/use92/.
48
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Technical Background Information for the UCMR
March 2000
TERBUFOS
ESTIMATED ANNUAL AGRICULTURAL USE
Average use of
Active Ingredient
Pounds per square mile
of county per year
D No Estimated Use
D = B.013
Crops
corn
sugar boots for smar
•OflnuDi
BWBBtCOm
Total
Pounda Appled
6,497,238
47^498
131,762
46,189
Percent
National Use
80,24
6. 66
£.52
aer
Figure 4.14. Terbufos—Estimated Annual Agricultural Use. National Pesticide Synthesis Project. Maps of Annual
Pesticide Use, 1992. United States Geological Survey. National Water Quality Assessment Pesticide Program.
Available on internet at http://water.wr.usgs.gov/pnsp/use92/.
49
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Technical Background Information for the UCMR
March 2000
Terbufos is an insecticide used on corn, sugar beet, grain, and sorghum crops. Terbufos appears on
National Pesticide Synthesis Project maps in EPA Regions 2, 3, 4, 5, 6, 7, 8, and 10. (See Figure 4.14)
Aeromonas hydrophila, the only UCMR (1999) List 2 microbiological contaminant, is not reported in
discharge data sources such as TRI. Aeromonas hydrophila, a bacterium that is indigenous to natural
waters, is associated with human populations and fecal waste. Population density and wastewater dis-
charge may affect prevalence, but its occurrence is considered to be ubiquitous in water distribution
systems nation-wide.
4.2.3. UCMR (1999) List 3 Contaminants
There is one chemical contaminant and seven microbiological contaminants on the UCMR (1999)
List 3. In general, the data available on the occurrence of the microbiological contaminants included on the
final 1998 CCL are very limited. Thus, EPA listed all but two of the microbiological contaminants as
occurrence priorities (the UCMR list). List 3 contaminants consist of lead-210 along with four viral and
three other microbiological contaminants. [One other bacterial contaminant, Aero-monas hydrophila, is
included in the UCMR (1999) List 2.]
Table 4.3. UCMR (1999) List 3 Contaminant Occurrence or Use by EPA Region
UCMR (1999) List 3 Contaminants
Contaminant
Potential Environmental
Source
EPA Regions
1234
Chemical Contaminants
Lead-210
Part of the uranium decay series;
natural occurrence due to atmospheric
fall out
5 6
7 8 9 10
Expected to occur in all Regions.
Microbiological Contaminants
Ad enovi ruses
Cyanobacteria (blue-green
algae), other freshwater
algae, and their toxins
Calicivi ruses
Coxsackievi ruses
Echovi ruses
Helicobacter pylori
Microsporidia
Fecal or hand to mouth transmission
Bloom in surface water bodies;
produce toxins
Contaminated food and water; raw
shellfish
Fecal or hand-to-mouth transmission
Fecal or hand-to-mouth transmission
Fecal or hand-to-mouth transmission
Occur in rivers, ponds, lakes, and
unfiltered water
Expected to occur in all Regions.
Expected to occur in all Regions.
Expected to occur in all Regions.
Expected to occur in all Regions.
Expected to occur in all Regions.
Expected to occur in all Regions.
Expected to occur in all Regions.
The microbiological contaminants are not known to exhibit geographically restricted occurrence,
although warmer regions may be susceptible to contamination for a longer period of time each year
compared to cooler regions. All List 3 contaminants are considered to have the potential to occur through-
out the United States.
Lead-210 (Pb-210) is an isotope in the uranium decay series along with polonium-210, radium-226, and
radon-222. Lead-210, with ahalf-life of 22 years, has been found in drinking water. EPA is aware of the
occurrence of these contaminant in shallow aquifers in Florida (Harada etal., 1989; Upchurch 1991), and
50
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Technical Background Information for the UCMR March 2000
in at least two other states. In addition, lead-210 is expected to occur naturally in essentially every part of
the country as atmospheric fallout.
Adenoviruses are associated with respiratory and gastrointestinal illnesses. Some of these viruses may be
spread via fecal-oral transmission. Adenoviruses discharged with sewage waste into lakes, rivers, and
streams can survive to reach water intakes of downstream systems. If sewage or treated sludges are
discharged to land, sufficient quantities of viruses may survive to contaminate the ground waters below.
Adenoviruses are expected to occur in every EPA Region.
Caliciviruses are associated with gastrointestinal illnesses. These viruses are spread through contaminated
water, food, and raw shellfish. Caliciviruses discharged with sewage waste into lakes, rivers, and streams
can survive to reach water intakes of downstream systems. If sewage or treated sludges are discharged to
land, sufficient quantities of viruses may survive to contaminate the ground waters below. Caliciviruses
are expected to occur in every EPA Region.
Coxsackieviruses are associated with gastrointestinal illnesses. These viruses are spread through fecal
transmission. Coxsackieviruses discharged with sewage waste into lakes, rivers, and streams can survive
to reach water intakes of downstream systems. If sewage or treated sludges are discharged to land, suffi-
cient quantities of viruses may survive to contaminate the ground waters below. Coxsackieviruses are
expected to occur in every EPA Region.
Cyanobacteria (blue-green algae), other freshwater algae, and their toxins may appear in surface
waters such as eutrophic lakes, rivers, streams, and reservoirs. Water systems using such sources are
probably most susceptible to cyanobacteria contamination. However, given that States and EPA Regions
have a wide diversity of water sources within them, this may be more of a local, rather than regional,
issue.
Echoviruses are associated with gastrointestinal illnesses. These viruses are spread through fecal trans-
mission. Echoviruses discharged with sewage waste into lakes, rivers, and streams can survive to reach
downstream water intakes of downstream systems. If sewage or contaminated treated sludges are dis-
charged to land, sufficient quantities of viruses may survive to contaminate the ground waters below.
Echoviruses are expected to occur in every EPA Region.
Helicobacter pylori is a bacterium that has been identified as a causative agent of human gastritis and
duodenal ulcers. Helicobacter pylori is spread through fecal or hand-to-mouth transmission and occurs
ubiquitously throughout the U. S. surface waters and ground water under the direct influence of surface
water are probably most vulnerable, so systems using these two sources may be more susceptible to
contamination. However, this contaminant is nonetheless expected to occur in every EPA Region.
Microsporidia are waterborne unicellular obligate protozoon parasites. Microsporidia do not seem to
have a restricted geographic distribution. Surface waters and ground water under the direct influence of
surface water are probably most vulnerable, so systems using these two may be more susceptible to
contamination. Because of possible zoonosis, regions with large animal stocks in their watersheds may be
particularly susceptible to contamination, but there is no evidence as of yet to support this theory.
4.3. Conclusions
Few UCMR (1999) contaminants display a restricted, or 'targeted', geographic distribution. Almost every
contaminant appears in at least seven of the ten EPA Regions, and even most of the exceptions are not
restricted to one individual area. The herbicide molinate (List 1), which has the most restrictive geographic
51
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Technical Background Information for the UCMR March 2000
distribution of the UCMR (1999) List contaminants, is used in four EPA Regions (although in Regions 4,
6, and 7 the areas of use are geographically conterminous).
4.4. References
7992 Census of Manufactures; Geographic Area Series. 1992. Bureau of the Census. Economics and
Statistics Administration. U.S. Department of Commerce. Available on the internet at http://www. census
.gov/prod/l/manmin/92area/92manufa.htm.
Agency for Toxic Substances and Disease Registry (ATSDR). 1990. Toxicological Profile for 1,2-
Diphenylhydrazine. Public Health Statement. Atlanta: U.S. Department of Health and Human Services,
Public Health Service. Available on the internet at http://www.atsdr.cdc.gov/ToxProfiles/phs9011 .html.
Agency for Toxic Substances and Disease Registry (ATSDR). 1995. Toxicological Profile for RDX.
Atlanta: U.S. Department of Health and Human Services, Public Health Service. Available on the internet
at http://www.atsdr.cdc.gov/tfacts78.html.
Harada, K., W.C. Burnett, P.A. LaRock, and J.B. Cowart. 1989. Polonium in Florida Groundwater and its
Possible Relationship to the Sulfur Cycle and Bacteria. Geochemica et Cosmochimica Acta. 53:143-150.
Kolpin, D.W., J.E. Barbash, and R.J. Gilliom. 1998. Pesticide National Synthesis Project. Occurrence of
Pesticides in Shallow Ground Water of the United States: Initial Results from the National Water-Quality
Assessment Program. National Water Quality Assessment Program. United States Geological Survey.
Larson, S.J., P.O. Capel, and M.S. Majewski. 1997. Pesticides in Surface Waters, volume three of the
series Pesticides in the Hydrologic System. Ann Arbor Press, Inc., Chelsea, Michigan.
National Center for Food and Agricultural Policy. 1995 Pesticide Use in U.S. Crop Production. National
Data Report. Washington, DC.
National Pesticide Synthesis Project. \992.Maps of Annual Pesticide Use, 1992. United States Geologi-
cal Survey. National Water Quality Assessment Pesticide Program. Available on the internet at http://
water.wr.usgs.gov/pnsp/use92/.
USEPA. 1994. Health Effects Notebook for Hazardous Air Pollutants; 1,2-Diphenylhydrazine. United
States Environmental Protection Agency Office of Air Quality Planning and Standards. Unified Air Toxics
Website. Available on the internet at http://www.epa.gov/ttn/uatw/hlthef/diph-zin.html.
USEPA. 1993. Manual of Methods for Virology; Chapter 1. EPA Publication No. EPA/600/4-84/013.
Available on the internet at http://www.epa.gov/nerlcwww/chap 1 .htm.
USEPA. 1998 (draft). Perchlorate Environmental Contamination: Toxicological Review and Risk Char-
acterization Based on Emerging Information. United States Environmental Protection Agency Office of
Research and Development. NCEA-1-0503. December 31, 1998. External Review Draft
USEPA. Toxic Release Inventory Database. Available on the internet at http://www.rtk.net/www/data/
tri^gen.html.
Upchurch, S.B. 1991. Radiochemistry of Uranium-Series Isotopes in Groundwater. Florida Institute of
Phosphate Research (05-022-092).
52
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Section 5. The UCMR Sampling
Rationale
As mandated by the 1996 SDWA Amendments, the purpose of the UCMR Program is to obtain
occurrence data to support future regulatory decisions. The data required to make these decisions must be
of high quality, and should provide an accurate reflection of the frequency of contaminant occurrence and
the level of human exposure in public drinking water. To provide data of this caliber, EPA is requiring
public water systems to monitor for UCMR (1999) List 1 contaminants over the course of a year, yet
target sample collection for some samples to the period of greatest vulnerability. EPA believes that this
approach will provide the most accurate data on possible human exposure to these contaminants given the
budgetary and implementation constraints of the UCMR Program. The rationale for this approach is
described below.
5.1. Sampling Plan for UCMR (1999) List 1 Contaminants
5.1.1. Sampling Locations
The nature and source of the chemical contaminant must be considered when designating a
sampling location. The contaminants on List 1 of the UCMR (1999) List all have environmental sources
related to various societal activities or waste disposal, such as the pesticides used for crop production, or
MTBE used as a gasoline additive. If chemicals were included that were produced in the water treatment
and distribution system, such as various disinfection by-products or lead (related to lead piping in parts of
a water system) this would dictate a different sampling strategy. The sampling location for the chemicals
on the UCMR (1999) List is at the entry point to the distribution system (EPTDS), i.e., a point after
treatment where water enters the delivery system to be used by the public, or the compliance monitoring
point monitoring point specified by the State or EPA under 40 CFR 141.24 (f)(l), (2), and (3).1 This is
the standard sampling location for drinking water chemical contaminants that originate in source water.
The EPTDS is generally considered the preferred sampling location for a program such as the UCMR that
needs to assess human exposure through drinking water. Concentrations in the raw source water may
change through treatment, thus sampling at the source would not necessarily provide an accurate measure
and could confound the analysis.
5.1.2. Temporal Variability and Vulnerability
A major factor considered in the design of the UCMR Program was the timing of sample collec-
tion, i.e., are there periods during the year that are more likely to find detections or greater concentrations
of a contaminant than others. As the UCMR attempts to develop an initial evaluation of these emerging
contaminants, it is important to optimize the sampling to maximize the likelihood of their detection. Yet the
possible sampling scenarios must also fit within a reasonable cost and burden framework for the public
water systems (PWSs), EPA, and the States. In addition, to the extent possible, the sampling strategy
should be compatible with the compliance sampling already required of PWSs. List 1 of the UCMR
(1999) List includes various synthetic organic compounds (SOCs; primarily pesticides), volatile organic
compounds (VOCs), and a man-made inorganic compound (perchlorate). To assess possible sampling
strategies for the List 1 contaminants, sampling strategies that accounted for the temporal variability of
more widely studied non-UCMR SOCs and VOCs were examined, with the goal of deriving an analogous
sampling strategy for the UCMR. The data reviewed below were compiled for EPA's considerations of
revisions to regulated chemical monitoring requirements. Further background information is presented in A
53
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Technical Background Information for the UCMR March 2000
Review of Contaminant Occurrence in Public Drinking Water Systems (1999; EPA 816-R-99-006),
particularly for the State-PWSs data discussed below.
5.1.2.1. General Trends
Water quality studies and monitoring throughout the United States have clearly shown that
occurrence and/or concentration for some contaminants may vary over time, both seasonally as well as
from year to year. The seasonality of contaminant occurrence, or period of peak concentration, commonly
varies with seasonal changes in the hydrologic cycle in relation to the source of contaminants and their fate
and transport characteristics. Particularly for land-applied or land-disposed contaminants, the seasonal
increase in the flux of water (e.g., spring rains) can mobilize contaminants and move them into surface or
ground water flow systems. For the most vulnerable of water systems, such as surface waters, unconfmed
shallow ground water, and karst flow systems, for example, contaminant occurrence or peak concentra-
tions typically occur during annual runoff and recharge periods. Targeting UCMR monitoring to these
vulnerable time periods improves the accuracy of exposure estimates. However, there are concerns about
the cost effectiveness of seasonal targeting approaches. If, for example, many of the List 1 contaminants
exhibit different seasonal patterns, trying to seasonally target all the different contaminants could lead to a
very complex and costly UCMR monitoring regimen.
For much of the United States east of the Rocky Mountains, many studies have shown the season
of greatest vulnerability for contaminant occurrence is the late-spring, early-summer runoff-recharge
period. This has been well established from detailed source water monitoring data, particularly for con-
taminants such as pesticides and nitrate (Larson etal, 1997; Barbash and Resek 1996; Hallberg 1989a;
Hallberg 1989b). For example, Figure 5.1 summarizes pesticide concentrations in streams from the USGS
NAWQA studies. This national summary shows the concentration of pesticides in agricultural areas
peaking from May through July. For streams draining urban areas the concentrations are lower, and they
do not show such pronounced seasonality, though May through July would still include most of the peak
period.
For deeper, more confined ground water systems, defining vulnerable periods is much more
difficult. The exact flow path is more complex, and the time of travel much greater, and these are depen-
dent on many factors unique to a particular well and aquifer setting (Hallberg and Keeney 1993). How-
ever, as depth of ground water increases (and vulnerability decreases), seasonal variability typically
decreases (Barbash and Resek 1996). There is no seasonal generality that can be applied to these deeper
ground water settings.
5.1.2.2. Synthetic Organic Compounds (SOCs)
State SDWA occurrence data were analyzed for seasonal patterns which might provide some
insight into possible UCMR monitoring schedules. Unraveling such patterns from data aggregated from
many different water sources and systems is difficult, at best. The clearest examples are for the high
occurrence pesticides. Figure 5.2 illustrates the typical seasonal pattern for atrazine (a regulated pesticide)
occurrence with peaks in May-July, but the number of CWSs with high monthly means decreases slowly
through the fall and winter. This is one way to examine occurrence patterns.
Figures 5.3 and 5.4 also illustrate seasonal patterns for pesticides, as well as the problems that
can be encountered in using drinking water data for such analyses. These data are from a State of Ohio
special study of pesticide/SOC occurrence in surface water systems (Ohio EPA 1998). May to July peaks
in the percentage of systems with detections are evident, particularly for the pesticides that occur more
intermittently. For atrazine, however, the months with the greatest percentage of systems with detections
appear to be September and December. It was concluded that the September and December peaks are
largely artifacts of the sampling regimen, and the systems required to sample. Not all systems sampled in
54
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Technical Background Information for the UCMR
March 2000
3
0>
•c 2
*
Pesticide Concentrations in Surface Water
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Agricultural Streams
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Urban Streams
Figure 5.1. Pesticide Concentrations in Surface Waters. This figure presents a summary of total pesticide
concentrations in streams samples monthly in the USGS NAWQA Program, for streams affected by runoff from
agricultural and urban lands. Adapted from Larson, S.J., R.J. Gilliom, and PD. Capel. 1999. Pesticides in
streams of the United States — Initial Results from the National Water-Quality Assessment Program: USGS
Water-Resources Investigations Report 98-4222, 92 p.
the fall and winter; only those systems that were known, or suspected to have year-round occurrence were
required to sample. Hence, in September 100 percent of the systems sampling had detections. The seasonal
occurrence pattern is more clearly defined looking at the maximum concentrations detected by month,
where May, June, and July clearly stand out.
As illustrated by this example, analyzing State PWS data can be complicated because so many
sources of variation have been aggregated. For example, State data include many different systems, with
different source waters and sampling schedules, sampling over various years, all in relation to various
contaminant source characteristics. This can result in "smoothing" out the seasonal variation (e.g., per-
centage of systems with atrazine, Figure 5.3), especially for persistent contaminants that may be present
all year. The aggregation of systems and source characteristics particularly confound analysis of ground
water systems, but also affects the analysis of surface water systems. For example, detailed studies by the
USGS and others have shown that the seasonal response in reservoirs may be very different than in
streams, and these are both typically identified simply as surface water sources in the PWS databases.
Small streams are more immediately affected by runoff events, and therefore contaminant concen-
trations are generally greater in small streams than in large streams (which integrate a greater area). While
this changes the details of temporal patterns (at the daily -weekly level), the broader seasonal patterns are
55
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Technical Background Information for the UCMR
March 2000
Jan March May July
Month
Sept
Nov
Figure 5.2. Number of CWSs with Monthly Mean Atrazine Concentrations Above 3.0 ug/L Data reflect monthly
mean atrazine concentrations in raw water. Data are from a special sampling study in Iowa, by Novartis Crop
Production (Novartis 1997; Clarkson et a/., 1997).
similar. Reservoirs, however, store these runoff-related events, and contaminant variations appear to be
dampened. The high concentrations that enter during runoff may be stored for some time (e.g., months),
and year-to-year variation may be more important than seasonal variations in reservoirs and lakes, de-
pending upon reservoir size, land use in the watershed, and the reservoir turnover rate (Battaglin and
Goolsby 1998; Scribner etal, 1996).
Some studies have also shown secondary peak concentrations of some pesticides in fall and winter
months with discharge from urban areas, but these are of much lesser magnitude than the spring period
occurrence peaks (Coupe etal., 1995). Also, seasonal patterns are different in the Pacific west, for
example, where fall and winter are important rainfall and recharge periods and patterns can be compli-
cated by irrigation schedules or release from irrigation storage reservoirs in the arid west (Larson et al,
1997; Kuivila and Foe 1995).
5.1.2.3. Volatile Organic Compounds (VOCs)
Many SOCs, the pesticide compounds in particular, exhibit strong seasonal occurrence patterns
because their application, or discharge into the environment, is concentrated seasonally. Particularly for
pesticides used in broad-scale grain production, the application season is relatively focused in the spring
and early summer and coincides with annual runoff and recharge periods. This coincidence is optimal to
produce seasonal patterns of pesticide occurrence in vulnerable waters. In contrast, VOCs do not typically
show such seasonality in source or discharge into the environment. Studies of individual water systems, or
hydrologic settings sometimes show patterns that parallel seasonal hydrologic patterns, but on a large
scale, no clear, general patterns emerge.
Figures 5.5 through 5.8 summarize various occurrence data by month and water source. The VOC
data were analyzed in a number of ways, ranging from the monthly number or percent of samples and
systems with detections (greater than the minimum reporting level [MRL], greater than one-half the
maximum contaminant level [MCL], and greater than the MCL), the percentage of detections per month as
56
-------
Technical Background Information for the UCMR
March 2000
Mnnt
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Figure 5.3. Percentage of Surface Water Systems with Detections and Maximum Concentration Detected, by
Month, for Alachlor, Atrazine, and Simazine, in Ohio (Ohio EPA 1998).
a function of all detections and the portion of systems sampling per month, as well as monthly concentra-
tions (median, QS^percentile, maximum). Even individual systems with common occurrence were isolated
to assess possible temporal trends.
No systematic trends were apparent. All the results look similar to the examples in Figures 5.5
through 5.8. There are no consistent seasonal patterns that emerge for VOCs. Figure 5.5 shows monthly
charts for xylene for several States. From the ground water systems from Illinois and the surface water
systems from Michigan a 'bell-shaped' occurrence pattern, peaking in mid summer might be surmised.
However, the Illinois surface water systems alternate peaks and declining values. Oregon shows a peak in
December, but this could be a function of Oregon's different climatic regimen.
57
-------
Technical Background Information for the UCMR
March 2000
flsrppn tpf ^'dem c Win Cvfeplpn c pf Mplplpphlp r, Et1
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Figure 5.4. Percentage of Surface Water Systems with Detections and Maximum Concentration Detected, by
Month, for Metolochlor, Metribuzin, Cyanazine, and Acetochlor, in Ohio (Ohio EPA 1998). (In the Metribuzin and
Cyanazine chart, Cyanazine is depicted in the gray/striped column.)
Other analysis in these States suggest that the patterns are more related to what systems are
sampling, rather than a seasonal pattern, especially when groups of related contaminants are viewed. For
example, Figure 5.6 shows several related VOC contaminants for one State. (These VOCs are light
molecular compounds that are constituents of gasoline and other petroleum distillates and generally show
similar behavior.) Hints of seasonal patterns for one contaminant are out of phase with others. For ground
water systems, for xylene, an overall "bell-shaped" pattern occurs, except that the lowest month is in the
middle of the bell. Figure 5.7 and 5.8 show a similar lack of pattern for the heavier VOCs (tetrachloroeth-
ylene and trichloroethylene), and all VOCs aggregated.
58
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Technical Background Information for the UCMR
March 2000
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Technical Background Information for the UCMR
March 2000
Ground Ws bar SJSLIGIYIS. in Atatrama-X^ene [>sfcKfioni
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Figure 5.6. Percentage of Systems with Detections of Xylene, Toluene, and Benzene, by Month and Water
Source, for Alabama.
tion record (generated from herbicide concentration data from a Midwestern river with high-ground water
baseflow), and three sampling scenarios. This concentration distribution is typical of strong seasonal
contaminant occurrence patterns commonly found in agrichemical impact studies. Without special treat-
ment, such a concentration pattern would also be apparent in finished drinking water derived from this
type of source (Hallberg 1989a; Hallberg etal., 1996).
In one scenario, quarterly water samples could be collected at times labeled A during the year.
This sampling regimen would, by chance or by choice, significantly underestimate the annual average
concentration. In scenario B, which collects one quarterly sample during the May-July peak period, an
60
-------
Technical Background Information for the UCMR
March 2000
Debclcre.
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Figure 5.7. Percentage of Systems with Detections of Tetrachloroethylene and Trichloroethylene, by Month and
Water Source, for Illinois.
underestimation of occurrence may still occur, but the sampling scenario would generate data with a better
representation of the peak season of contaminant occurrence.
Statistical studies of surface water sampling strategies (e.g., Battaglin and Hay 1996) show that a
strategy which incorporates sampling during spring and early summer runoff periods provides a more
accurate representation of annual occurrence than does random quarterly sampling (that can miss or avoid
these runoff-period months, as in scenario A in Figure 5.9). In these studies, the USGS evaluated how ten
different sampling strategies affected the accuracy of the estimates of annual mean concentration of
herbicides. The accuracy of a particular strategy's estimate was computed by comparing time-weighted
annual mean concentrations calculated from detailed water sampling at 17 locations with the annual mean
61
-------
Technical Background Information for the UCMR
March 2000
asw-
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Figure 5.8. Percentage of Systems with Detections (>MRL, >0.5MCL) of Any of the 21 Regulated VOCs, by Month
and Water Source, for Iowa.
estimated by each sampling strategy, using 1000 Monte Carlo simulations for each strategy. In other
words, each sampling strategy was simulated using 1000 different combinations of sampling times
throughout the year. The results were compared to a tolerance value around the actual mean from the
detailed water-quality data. Pertinent results are summarized in Table 5.1. A value of ± 0.75 (ig/L around
the actual annual concentration mean was used for the tolerance.2 The table summarizes the percentage of
sampling simulations within tolerance (i.e., over or under the actual mean plus or minus the tolerance
value). A result over or under the tolerance value indicates that a sampling strategy overestimates or
underestimates, respectively, the actual mean concentration.
Quarterly sampling underestimated the mean in 20 percent of the random simulations, and was
within the tolerance 63 percent of the time, assuming a random distribution. The quarterly results appear
much more accurate than Scenario A would imply because the random simulation results in at least one-
third of the simulations collecting samples during the peak months. Monthly sampling was the most
accurate, but such a sampling strategy for the UCMR would be particularly burdensome both with respect
to cost and burden to the PWSs that will be collecting samples. However, three scenarios are nearly as
accurate as monthly, and would not require as high a frequency of sampling.
Strategies which sample once each in May and June (and consider the other 10 months as zeros),
or once in April, May, and June (with 9 zeroes), or once each in April, May, June, and July (with 8 zeros),
range from 81 percent to 84 percent within the tolerance of the actual annual mean. A sampling scenario
such as C, in Figure 5.9, could provide a more accurate view of drinking water quality, while still only
requiring four samples per year. This sampling strategy targets three samples in the identified vulnerable
62
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Technical Background Information for the UCMR
March 2000
C
\
A
A
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£rid Quarter
3rd Quarte-i
5C!
Figure 5.9. Schematic Annual Contaminant Concentration Profile, with Three Sampling Scenarios (A, B, and C).
The schematic profile is derived from actual herbicide concentration data from a Midwestern stream.
months, and collects a fourth sample during the off-season to provide a more complete record. With the
strong seasonal contaminant occurrence patterns, the fall-winter background sample would have a similar
numerical effect as the "zero" assumption in the simulations, but would provide a more continuous record.
One ground water study suggests that the more vulnerable aquifers also show seasonal contami-
nant occurrence peaks during these periods (Pinsky et a/., 1997). Targeting the peak periods would also be
Table 5.1. Percentage of Monte Carlo Simulations Within, Over, or Under ± 0.75 ug/L
of theTime-weighted Annual Mean Atrazine Concentration.
Sampling Strategy
1 each, April, May, June, July
Quarterly
1 in June w/ 1 1 zeros
1 each in May, June, w/ 10 zeros
1 each in April, May, June w/ 9 zeros
1 each in April, May, June, July w/ 8 zeros
Monthly
Percentage of Simulations withing Tolerance of ±0.75
ug/L of the MCL
Within
39%
63%
58%
81%
82%
84%
85%
Over
53%
16%
1%
5%
5%
6%
7%
Under
7%
20%
40%
14%
13%
9%
8%
Note: Annual mean atrazine concentrations in the study were time-weighted. There were 1000 simulations generated for each of the
seven sampling strategies listed here, and were conducted for all sites. The 0.75 |jg/L is equivalent to 25% of the atrazine MCL
(Battaglin and Hay 1996).
63
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Technical Background Information for the UCMR March 2000
appropriate for such aquifers. From the data and literature reviewed, such a targeting strategy for List 1
SOCs would be adequate for exposure estimates. Most of the data suggest that most organic contaminants
will vary in the same seasonal pattern, or, as with many VOCs, will show little systematic variance.
Hence, List 1 VOCs might be sampled on a similar schedule and perhaps not lose resolution. However,
this sampling strategy will always be most effective if States and systems use their knowledge of local
conditions and activities to define seasonal vulnerability patterns, and to adjust sampling schedules
accordingly. For example, in the Pacific west, some pesticides show peak concentrations in fall-winter
because of the use of pesticides on orchards during their dormant season. The fall-winter months comprise
the rain/runoff season in this climate, and, in some cases, dictate reservoir release schedules (Kuivila and
Foe 1995; Larson eta/., 1997).
There is no simple, single guideline that addresses all contaminant and water source situations and
yet keeps in balance the frequency and burden of monitoring. Current contaminant source and fate knowl-
edge is incomplete, particularly for many of the new contaminants included in the UCMR. Also, consider-
ing the variety of List 1 contaminants (various pesticides, VOCs, and an IOC) and scheduling constraints
(both laboratory capacity and compatibility or coordination with current compliance monitoring), a highly
targeted seasonal approach may not be feasible or warranted. Alternatively, requiring PWSs to collect
samples for UCMR contaminants monthly would be particularly burdensome both with respect to cost and
burden to the PWSs conducting sampling. Given these considerations, EPA is requiring that PWSs using
surface water, or ground water under the influence of surface water, sample for UCMR (1999) List 1
contaminants four times per year, and that systems using ground water sample two times per year.
For all systems, one of the sampling events must fall between May 1 and July 31, or an alternative
period of greatest vulnerability, as specified by the State orEPA(§141.40(a)(5)). An example of an
alternative period would be September 1 to November 30 for States in the Pacific Northwest. For systems
using groundwater, the other sampling event must be between 5 and 7 months either before or after the
sampling event during the May-July vulnerable period, or other vulnerable period as specified by the State
or EPA (§141.40(a)(5)). Surface water systems must sample in the same month of each of four consecu-
tive quarters (i.e., January, April, July, and October) to ensure that one sample is collected during the
May-July vulnerable period, or other vulnerable period as specified by the State or EPA (§141.40(a)(5)).
By requiring that some samples are targeted to the most vulnerable May through July period, EPA hopes
to ensure representation of the peak vulnerable period for many UCMR (1999) List 1 contaminants. Also,
as exposure estimates do not have to be based exclusively on an average of four measures per year, EPA is
requiring systems using ground water to sample only two times per year (§141.40(a)(5)). All UCMR data
can be evaluated to construct a more accurate model of seasonal occurrence that would allow additional
considerations to be included.
5.2. Sampling Plan for UCMR (1999) List 2 Contaminants
This document is intended to provide technical background information for the UCMR, with a
focus on the UCMR (1999) List 1 contaminants. However, some information is available that may be used
in developing sampling plans for the Screening Survey and Pre-Screen Testing components of the revised
UCMR Program. EPA is currently developing the sampling plan for the Screening Surveys. Additional
information will be made available upon promulgation of the Screening Survey component of the UCMR
Program. Included below is a brief discussion of issues related to the development of a sampling plan for
the UCMR (1999) List 2 contaminants.
5.2.1. Sampling for List 2 Chemical Contaminants
As discussed above, EPA is currently developing the sampling plan for the UCMR (1999) List 2
contaminants. At this time, EPA has not evaluated various sampling strategies specifically for the List 2
64
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Technical Background Information for the UCMR March 2000
chemical contaminants. However, EPA anticipates that the sampling plan for List 2 chemicals will be very
similar to that developed for the List 1 contaminants, at least with respect to frequency, timing, and
location of sampling. Nearly all of the List 2 chemicals are either agricultural SOCs or industrial VOCs.
Thus, many of the issues discussed above are relevant to List 2 chemicals as well. The only naturally-
occurring chemical contaminant on List 2 is polonium-210, an alpha-emitting decay product of radon-222
and part of the uranium decay series. Data are limited with respect to the temporal variability of occur-
rence of this contaminant, but it is unlikely, given the other contaminants to be included in the Screening
Surveys, that a different sampling plan would be necessary for monitoring polonium-210.
5.2.2. Sampling for Aeromonas hydrophila
As EPA had originally proposed to include Aeromonas hydrophila on List 1 of the UCMR and
thus monitor for it under Assessment Monitoring, preliminary data have already been collected and
evaluated for use in developing a monitoring strategy for this contaminant. A summary of this information
is provided below. However, it is important to note that EPA is reevaluating these data and continuing to
develop an appropriate sampling plan for Aeromonas. Additional information on the UCMR sampling
strategy for Aeromonas will be made available at the time of promulgation of the Screening Survey
component of the UCMR Program.
5.2.2.1. Initial Occurrence Data
Aeromonas hydrophila is a bacterium that is indigenous to natural waters. It has been implicated
as a cause of traveler's diarrhea and other types of infection. Transmission of Aeromonas is suspected to
occur via a waterborne route, although a definite link has not been established (Holmes et a/., 1996).
Aeromonas has been observed in drinking water distribution systems, especially in locations with low
residual chlorine levels (Holmes etal., 1996). Because ofthe possible occurrence of Aeromonas in treated
drinking water and its potential health effects, EPA feels it necessary to obtain more information about the
occurrence of Aeromonas in drinking water and the factors responsible for its presence.
Some research has been done on Aeromonas occurrence and factors that influence its occurrence
in water distribution systems. Gavriel and colleagues detected Aeromonas in 21 of 31 treated water
reservoirs in Scotland (Gavriel et al., 1998). These authors found that, in general, the likelihood of
recovering Aeromonas in the reservoirs decreased as chlorine levels increased. However, three reservoirs
that were positive for Aeromonas in more than 10 percent of samples had residual chlorine levels in excess
of 0.2 mg/L. This study concluded that maintenance of a chlorine residual in the distribution network is
insufficient on its own to control aeromonads. Holmes and Nicolls (1995) found that Aero-monas was
controlled by a residual chlorine level of 0.2 mg/L in the Severn Trent area ofthe United Kingdom,
although Aeromonas was detected when the residual chlorine level was below 0.2 mg/L. For example, data
in this paper indicated that 200 Aeromonas /100 mL were found in a sample that had a chlorine residual of
0.15 mg/L. Holmes and colleagues (1996) reported that Aeromonas aftergrowth was more common in the
end of a water distribution system where the age ofthe water after treatment was more than 72 hours.
Similarly, Stelzer and colleagues (1992) found higher Aeromonas counts at locations greater than 6 km
from the water treatment facility. Havelaar and coworkers (1990) also reported that the greatest amount of
Aeromonas regrowth occurred in the peripheral parts ofthe distribution system. Other studies reporting
the presence of Aeromonas in chlorinated drinking water include LeChevallier and colleagues (1982),
Burke and colleagues (1984b), and Kuhn and colleagues (1997).
5.2.2.2. Factors Affecting Aeromonas Occurrence
While these studies reported Aeromonas in chlorinated drinking water (often with reduced levels
of residual chlorine), Hernandez and coworkers (1997) found that residual chlorine levels of 0.29 to 0.47
mg/L were effective in controlling Aeromonas. In fact, Holmes and colleagues (1996) stated that the free
65
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Technical Background Information for the UCMR March 2000
chlorine level was one of the major factors that influence the growth ofAeromonas in drinking water
supplies.
Another major factor that influences Aeromonas growth in treated drinking water is water tem-
perature (Holmes etal, 1996). Data from Burke and colleagues (1984b) show that water temperature is a
determining factor for Aeromonas populations in untreated surface water or treated water from service
reservoirs where there is a consistently low level of chlorine residual. Furthermore, Burke and colleagues
(1984a) state that Aeromonas was generally found in unchlorinated drinking water at temperatures greater
than 14.5° C. Holmes and Nicolls (1995) found Aeromonas to be more abundant in treated water during
the warmer months in England (especially July through October) when temperature was higher and
residual chlorine levels were lower.
Holmes and colleagues (1996) have speculated that Aeromonas may be introduced into treated
water distribution systems when Aeromonas is abundant in source water and when water is ineffectively
treated. Meheus and Peters (1989) reported different removal efficiencies ofAeromonas by different
treatment processes. Aeromonas was isolated from 34 percent of samples from a distribution system where
ground water was used and water treatment consisted of sedimentation and rapid sand filtration, but not
chlorination (Burke etal., 1984a).
Once in the distribution system, Aeromonas may maintain itself in treated water by growth in
biofilms. Mackerness and colleagues (1991) found that Aeromonas could become a member of a bacterial
biofilm. The biofilm appeared to protect Aeromonas since it was not killed by 0.3 mg/L of mono-chloram-
ine. Holmes and Nicolls (1995) examined Aeromonas in biofilms from pipe sections using the methods of
LeChevallier and coworkers (1987), in which the biofilm was scraped off the walls of the section of pipe.
Aeromonas was detected in 30 percent of the biofilms examined at an average density of 118 CFU/g wet
weight of biofilm. The biofilm in the pipe was exposed to a solution of 1 mg/L of chlorine for 30 minutes.
After this treatment, Aeromonas was still detected in 10 percent of the pipe section biofilms.
These reports indicate that Aeromonas hydrophila is likely to occur in drinking water, and even
chlorinated drinking water. Detections ofAeromonas tend to be more common at the distal ends of distri-
bution systems (i.e., when the residual chlorine level is low), and at elevated ambient water temperatures
(i.e., above 14.5° C). These findings also indicate that higher levels of residual chlorine may be effective in
controlling Aeromonas. However, Aeromonas hydrophila may enter a distribution system despite treat-
ment, and once in a system may grow in biofilms where it may be protected from chlorine. These data
suggest that a monitoring program for Aeromonas in water distribution systems is merited.
5.2.2.3. Aeromonas Sampling
Although no microbiological contaminants are included on List 1 of the UCMR (1999) List, EPA
identified two locations that could be used for sampling microbiological contaminants under the UCMR.
These location are:
(1) a site below a representative EPTDS that is used for taking total coliform samples, and
(2) a site in the distribution system that has the maximum residence time or lowest disinfectant
residual.
The first sampling location would presumably give negative results most or all of the time in chlorinated
distribution systems. This sample location would indicate what normal exposure levels for Aeromonas are
for most of the population when a system is functioning properly. The second sample from a site in the
distribution system that has the maximum residence time or lowest disinfectant residual would represent
Aeromonas exposure by a subset of the population of water consumers that had a greater likelihood of
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using water with a reduced chlorine residual. Reports such as Stelzer and colleagues (1992) and Havelaar
and colleagues (1990) present evidence thatAeromonas could occur in treated water under this condition.
EPA will consider monitoring forAeromonas at these sampling points when developing an appropriate
sampling strategy.
One suggestion being considered for the UCMR Program is to enumerate Aeromonas in biofilms
in water distribution pipes in a study similar to that conducted by LeChevallier and coworkers (1987).
While this might indicate whether water distribution systems were harboring populations of Aeromonas, it
would not represent exposure of those consuming water since most Aeromonas cells would remain in
biofilms. Additionally, the effort and expense of obtaining pipe sections would limit the size of a sample
that could be taken.
Factors that could affect Aeromonas presence in treated water include water temperature and
operation of water treatment processes. Since changes in water temperature during the annual cycle could
have a considerable effect on the size of Aeromonas populations encountered in water, EPA may require
the collection of several samples over the course of ayearto document these changes in population size.
Additionally, a higher frequency of sampling in a given system is more likely to detect events where there
may have been a change in the effectiveness of water treatment.
Samples to be analyzed forAeromonas may be accompanied with information on water tempera-
ture, pH, turbidity, free disinfectant residual, and total disinfectant residual. These data, in addition to
information on source water type, method of treatment, and other information will assist in the interpreta-
tion of the Aeromonas hydrophila occurrence data collected under this regulation. With these data, EPA
intends to ascertain which factors are important in determining whether Aeromonas occurs in drinking
water.
5.3. Sampling Plan for UCMR (1999) List 3 Contaminants
While EPA has begun to develop a monitoring strategy for the UCMR (1999) List 3 contami-
nants, this development is still in the very early stages of planning. Information on known occurrence and
possible analytical methods to be used for monitoring the List 3 microbiological contaminants has been
collected and summarized in the draft report entitled Methods and Occurrence Information for the UCMR
List 3 Microbiological Contaminants, available from Rachel Sakata of US EPA's Office of Ground Water
and Drinking Water. As with the List 2 contaminants, EPA will provide additional information on a
sampling plan for the List 3 contaminants when the Pre-Screen Testing component of the UCMR Program
is promulgated.
5.4. References
Barbash, J.E., and E.A. Resek. 1996. Pesticides in Ground Water, vol. 2 of Pesticides in the Hydrologic
System. Ann Arbor Press, Inc., Chelsea, Michigan.
Battaglin, W. and D. Goolsby. 1998. Regression Models of Herbicide Concentrations in Outflow from
Reservoirs in the Midwestern USA, 1992-1993. Journal of the American Water Works Association.
1369:34-6.
Battaglin, W. and L. Hay. 1996. Effects of sampling strategies on estimates of annual mean herbicide
concentrations in Midwestern rivers. Environmental Science and Technology. 30:889-896.
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Technical Background Information for the UCMR March 2000
Burke, V., J. Robinson, M. Gracey, D. Peterson, N. Meyer, and V. Haley. 1984a. Isolation ofAeromonas
spp. from an unchlorinated domestic water supply. Applied and Environmental Microbiology. 48(2):367-
370.
Burke, V., J. Robinson, M. Gracey, D. Peterson, and K. Paarthridge. 1984b. Isolation ofAeromonas
hydrophila from a metropolitan water supply: seasonal correlation with clinical isolates. Applied and
Environmental Microbiology. 48(2): 3 61 -3 66.
Clarkson, J.R., N.A. Hines, D.P Tierney, and B.R. Christensen. 1997. Human Exposure to Atrazine and
Simazine via Ground and Surface Drinking Water. Novartis Crop Protection, Inc. Study No. 696-95. EPA
MRID No. 44252122.
Coupe, R.H., D.A. Goolsby, J.L. Iverson, D.J. Markovchik, and S.D. Zaugg. 1995. U.S. Department of
the Interior. Pesticide, Nutrient, Water-Discharge, and Physical-Property Data for the Mississippi River
and Some of Its Tributaries, April 1991-September 1992. Open File Report 93-657, U.S. Geological
Survey.
Gavriel, A.A., J.P.B. Landre, A.J. Lamb. 1998. Incidence of mesophilic Aeromonas within a public
drinking water supply in north-east Scotland. Journal of Applied Microbiology. 84:383-392.
Hallberg, G.R. 1989a. Pesticide pollution of groundwater in the humid United States. Agriculture, Ecosys-
tems, and Environment. 26:299-367.
Hallberg, G.R. 1989b. Nitrate in groundwater in the United States. In Folet, R.F., ed., Nitrogen Manage-
ment and Groundwater Protection. Elsevier Science, Amsterdam, pp. 35-74.
Hallberg, G.R., and D. Keeney. 1993. Nitrate. In Alley, W.A., ed., Regional Ground-Water Quality. Van
Nostrand Reinhold, New York, NY. pp. 297-322.
Hallberg, G.R, D.G. Riley, J.R. Kantemneni, PJ. Weyer, and R.D. Kelley. 1996. Assessment of Iowa
Safe Drinking Water Act Monitoring Data: 1987-1995. University Hygienic Laboratory Research Report
97-1.
Havelaar, A.H., J.F.M. Versteegh, and M. During. 1990. The presence ofAeromonas in drinking water
supplies in the Netherlands. ZentralblHyg. 190:236-256.
Hernandez, S., P., R. Rodriquez de Garcia, D. Di Egidio and M.. Estrada. 1997. Chlorination treatment as
a control ofAeromonas spp. in drinking water. InternationalJournal of Environmental Health Research.
7:355-359.
Holmes, P. and L.M. Nicolls. 1995. Aeromonads in drinking-water supplies: their occurrence and signifi-
cance. Journal of the Chartered Institution of Water and Environmental Management. 9(5):464-469.
Holmes, P., L.M. Nicolls, and D.P. Sartory. 1996. The ecology of mesophilic Aeromonas in the aquatic
environment, pp.127-150. In: The Genus Aeromonas. B. Austin, M. Altwegg, P.J. Gosling, S.W. Joseph
(eds.) John Wiley and Sons, Chichester.
Kuhn, I., A. Gorel, G. Huys, P. Janssen, K. Kersters, K. Krovacek, and T.A. Stenstrom. 1997. Diversity,
persistence, and virulence ofAeromonas strains isolated from drinking water distribution systems in
Sweden. Applied and Environmental Microbiology. 63(7):2708-2715.
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Kuivila, K.M., and C.G. Foe. 1995. Concentartions, Transport, and Biological Effects of Dormant Spray
Pesticides in the San Francisco Estuary California. Environmental Toxicology and Chemistry. 14(7):
1141-1150.
Larson, S.J., P.D. Capel, and M.S. Majewski. 1997. Pesticides in Surface Waters, vol. 3 of Pesticides in
the Hydrologic System. Ann Arbor Press, Inc., Chelsea, Michigan.
LeChevallier, M.W., T.M. Babcock, and R.G. Lee. 1987. Examination and characterization of distribution
system biofilms. Applied and Environmental Microbiology. 53(12):2714-2724.
LeChevallier, M.W., T.M. Evans, R.J. Seidler, O.P. Daily, B.R. Merrell, D.M. Rollins, and S.W. Joseph.
1982. Aeromonas sobria in chlorinated drinking water supplies. Microbial Ecology. 8:325-333.
Mackerness, C.W., J.S. Colbourne, and C.W. Keevil. 1991. Growth of Aeromonas hydrophila and
Escherichia coll in a distribution system biofilm model. Proceedings of the United Kingdom Symposium
on Health-Related Water Microbiology. London, IAWPRC. 131-138.
Meheus, J. and P. Peters. 1989. Preventive and corrective actions to cope with Aeromonas growth in water
treatment. Water Supply. Vol. 7, Rio, PI0-1-PI0-4.
Novartis Crop Protection, Inc. 1997. Voluntary Atrazine Monitoring Program at Selected Community
Water Systems: Iowa 1996. Technical Report 6-97, Environmental and Public Affairs Department.
Ohio Environmental Protection Agency (EPA). 1998. Pesticide Special Study. Division of Drinking and
Ground Waters. Available at http://www.epa.state.oh.us/ddagw/pestspst.html.
Pinsky, P.M., M. Lorber, K. Johnson, B. Kross, L. Burmeister, A. Wilkins, and G. Hallberg. 1997. A
study of the temporal variability of atrazine in private well water. Environmental Monitoring and Assess-
ment. 47:197-221.
Scribner, E.A., D.A. Goolsby, E.M. Thurman, M.T. Meyer, and W.A. Battaglin. 1996. U.S. Department
of the Interior. Concentrations of Selected Herbicides, Herbicide Metabolites, and Nutrients in Outflow
from Selected Midwestern Reservoirs, April 1992 Through September 1993. Open File Report 96-363,
USGS.
Stelzer, W., J. Jacob, J. Feuerpfeil and E. Schulze. 1992. A study of the prevalence of aeromonads in a
drinking water supply. Zentralbl. Mikrobiol. 147:231-235.
Notes
1 If the compliance monitoring point for a particular system is for source water, and any contami-
nant on the UCMR ( 1 999) List is detected, the systems must then sample at the EPTDS unless the State or
EPA determine that sampling at the EPTDS is unnecessary because no treatment was instituted between
the source water and the distribution system that would affect measurement of the contaminant
2The value of 0.75 (jg/L is equivalent to 25 percent of the MCL of 3 (Jg/L, the MCL for atrazine.
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Appendix A. Abbreviations and
Acronyms
2,4-DNT - 2,4-dinitrotoluene
2,6-DNT - 2,6-dinitrotoluene
4,4'-DDE - 4,4'-dichloro dichlorophenyl ethylene, a degradation product of DDT
Alachlor ESA - alachlor ethanesulfonic acid, a degradation product of alachlor
AOAC - Association of Official Analytical Chemists
APHA - American Public Health Association
ASDWA - Association of State Drinking Water Administrators
ASTM - American Society for Testing and Materials
BGM - Buffalo Green Monkey cells, a specific cell line used to grow viruses
CAS - Chemical Abstract Service
CASRN - Chemical Abstract Service Registry Number
CCL - Contaminant Candidate List
CCR - Consumer Confidence Reports
CERCLA - Comprehensive Environmental Response, Compensation & Liability Act
CFR - Code of Federal Regulations
CPU - colony forming unit
CFU/mL - colony forming units per milliliter
CWS - community water system
DCPA - dimethyl tetrachloroterephthalate, chemical name of the herbicide dacthal
DCPA mono-
and di-acid
degradates - degradation products of DCPA
DDE - dichloro dichlorophenyl ethylene, a degradation product of DDT
DDT - dichloro diphenyl trichloroethane, a general insecticide
DMA - deoxyribonucleic acid
EDL - estimated detection limit
EDSTAC - Endocrine Disrupter Screening and Testing Advisory Committee
EPA - Environmental Protection Agency
EPTC - s-ethyl-dipropylthiocarbamate, an herbicide
EPTDS - Entry Point to the Distribution System
ESA - ethanesulfonic acid, a degradation product of alachlor
FACA - Federal Advisory Committee Act
FTE - full-time equivalent
GC - gas chromatography, a laboratory method
GLI method - Great Lakes Instruments method
GW - ground water
GUDI - ground water under the direct influence (of surface water)
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HPLC
ICR
IRFA
IMS
IRIS
IS
- high performance liquid chromatography, a laboratory method
- Information Collection Request / Rule
- initial regulatory flexibility analysis
- immunomagnetic separation
- Integrated Risk Information System
- internal standard
km
- kilometer
LLE - liquid/liquid extraction, a laboratory method
MAC - Mycobacterium avium complex
MOA - Memorandum of Agreement
MCL - maximum contaminant level
MDL - method detection limit
MRL - minimum reporting level
MS - mass spectrometry, a laboratory method
MS - sample matrix spike
MSD - sample matrix spike duplicate
MTBE - methyl tertiary-butyl ether, a gasoline additive
NAWQA - National Water Quality Assessment Program
NCFAP - National Center for Food and Agricultural Policy
NCOD - National Drinking Water Contaminant Occurrence Database
NDWAC - National Drinking Water Advisory Council
NERL - National Environmental Research Laboratory
NIRS - National Inorganic and Radionuclide Survey
NPS - National Pesticide Survey
NTIS - National Technical Information Service
NTNCWS - non-transient non-community water system
NTTAA - National Technology Transfer and Advancement Act
OGWDW - Office of Ground Water and Drinking Water
OMB - Office of Management and Budget
OPP - Office of Pesticide Programs
PAH - Poly-aromatic hydrocarbon
PA - Partnership agreement
PB - particle beam
PBMS - Performance-Based Measurement System
pCi/L - picocuries per liter
PCR - polymerase chain reaction
210Pb - lead-210 (also Pb-210), a lead isotope and radionuclide; part of the uranium decay
series
210Po - polonium-210 (also Po-210), a polonium isotope and radionuclide; part of the uranium
decay series
PWS - Public Water System
PWSF - Public Water System Facility
QA - quality assurance
QC - quality control
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RDX - royal demolition explosive, hexahydro-1,3,5-trinitro-1,3,5-triazine
RFA - Regulatory Flexibility Act
RPD - relative percent difference
RSD - relative standard deviation
SBREFA - Small Business Regulatory Enforcement Fairness Act
SD - standard deviation
SDWA - Safe Drinking Water Act
SDWIS - Safe Drinking Water Information System
SDWIS FED - the Federal Safe Drinking Water Information System
SIC - Standard Industrial Classification
SM - Standard Methods
SMF - Standard Compliance Monitoring Framework
SOC - synthetic organic compound
SPE - solid phase extraction, a laboratory method
SRF - State Revolving Fund
STORE! - Storage and Retrieval System
SW - surface water
TBD - to be determined
TNCWS - transient non-community water system
TRI - Toxic Release Inventory
UCMR - Unregulated Contaminant Monitoring Regulation/Rule
UCM - Unregulated Contaminant Monitoring
UMRA - Unfunded Mandates Reform Act of 1995
URCIS - Unregulated Contaminant Information System
USEPA - United States Environmental Protection Agency
UV - ultraviolet
VOC - volatile organic compound
ug/L - micrograms per liter
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Appendix B. Definitions
Assessment Monitoring means sampling, testing, and reporting of listed contaminants that have available
analytical methods and for which preliminary data indicate their possible occurrence in drinking water.
Assessment Monitoring will be conducted forthe UCMR (1999) List 1 contaminants.
Index Systems means a limited number of small CWSs and NTNCWSs, selected from the Assessment
Monitoring systems in State Plans, that will be required to provide more detailed and frequent
monitoring forthe UCMR (1999) List 1 contaminants (§141.40(a)(6)). The Index Systems will be
selected to geographically coincide with watersheds and areas studied under the United States
Geological Survey's National Water Quality Assessment program. In addition to the reporting
information required for Assessment Monitoring, the Index Systems must also report information on
system operating conditions (such as water source, pumping rates, and environmental setting)
(§141.40(a)(6)). These systems must monitor each year of the 5-year UCMR cycle, with EPA paying for
all reasonable monitoring costs (§141.40(a)(4)(i)(A)). This more detailed and frequent monitoring will
provide important information with which EPA can more fully evaluate the conditions under which small
systems operate.
Listed contaminant means a contaminant identified as an analyte in Table 1, §141.40(a)(3) of the
Unregulated Contaminant Monitoring Regulation (UCMR). To distinguish the current 1999 UCMR listed
contaminants from potential future UCMR listed contaminants, all references to UCMR contaminant
lists will identify the appropriate year in parenthesis immediately following the acronym UCMR and
before the referenced list. For example, the contaminants included in the UCMR (1999) List include the
component lists identified as UCMR (1999) List 1, UCMR (1999) List 2 and UCMR (1999) List 3
contaminants.
Listing cycle means the 5-year period for which each revised UCMR list is effective and during which no
more than 30 unregulated contaminants from the list may be required to be monitored. EPA is
mandated to develop and promulgate a new UCMR List every 5 years.
Monitored systems means all community water systems serving more than 10,000 people, and the
national representative sample of community and non-transient non-community water systems serving
10,000 or fewer people that are selected to be part of a State Plan for the UCMR. (Note that for this
round of Assessment Monitoring, systems that purchase their primary source of water are not included
in the monitoring.)
Monitoring (as distinct from Assessment Monitoring) means all aspects of determining the quality of
drinking water relative to the listed contaminants. These aspects include drinking water sampling and
testing, and the reviewing, reporting, and submission to EPA of analytical results.
Mosf vulnerable systems (or Systems most vulnerable) means a subset of 5 to not more than 25
systems of all monitored systems in a State that are determined by that State in consultation with the
EPA Regional Office to be most likely to have the listed contaminants occur in their drinking waters,
considering the characteristics of the listed contaminants, precipitation, system operation, and
environmental conditions (soils, geology and land use).
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Pre-Screen Testing means sampling, testing, and reporting of the listed contaminants that may have newly
emerged as drinking water concerns and, in most cases, for which methods are in an early stage of
development. Pre-Screen Testing will be conducted by a limited number of systems (up to 200). States will
nominate up to 25 of the most vulnerable systems per State for Pre-Screen Testing. The actual Pre-Screen
Testing systems will be selected from the list of nominated systems through the use of a random number
generator. Pre-Screen Testing will be performed to determine whether a listed contaminant occurs in
sufficient frequency in the most vulnerable systems or sampling locations to warrant its being included in
future Assessment Monitoring or Screening Surveys. Pre-Screen Testing will be conducted forthe UCMR
(1999) List 3 contaminants.
Random Sampling is a statistical sampling method by which each member of the population has an
equal probability (an equal random chance) of being selected as part of a sample (the sample being a
small subset of the population which represents the population as a whole).
Representative Sample (or National Representative Sample) means a small subset of all community
and non-transient non-community water systems serving 10,000 or fewer people which EPA selects
using a random number generator. The systems in the representative sample are selected using a
stratified random sampling process that ensures that this small subset of systems will proportionally
reflect (is "representative" of) the actual number of size- and water type-categories of all small systems
nationally. In finalizing State Plans, a State may substitute a system from the replacement list for a
system selected as part of the original representative sample, if a system on the representative sample
list in the State Plan is closed, merged or purchases water from another system.
Sampling means the act of collecting water from the appropriate location in a public water system (from
the applicable point from an intake or well to the end of a distribution line, or in some limited cases, a
residential tap) following proper methods for the particular contaminant or group of contaminants.
Sampling Point means a unique location where samples are to be collected.
Screening Survey means sampling, testing, and reporting of the listed contaminants for which analytical
methods are recently developed and have uncertain potential for occurrence in drinking water by a
subset of approximately 300 systems from all monitored systems selected through use of a random
number generator for public water system identification numbers. These systems must conduct the
Screening Survey for the contaminants on UCMR (1999) List 2 as will be further described in the List 2
Rule (§141.40(a)(7)). Two Screening Surveys may be conducted forthe UCMR (1999) List 2
contaminants.
State means, forthe purposes of this section, each of the fifty States, the District of Columbia, U.S.
Territories, and Tribal lands. Forthe national representative sample, Guam, the Commonwealth of
Puerto Rico, the Northern Mariana Islands, the Virgin Islands, American Samoa, and the Trust
Territories of the Pacific Islands are each treated as an individual State. All Tribal water systems in the
U.S. which have status as a State under Section 1451 of the Safe Drinking Water Act for this program
will be considered collectively as one State for the purposes of selecting a representative sample of
small systems.
State Monitoring Plan (or State Plan) means a State's portion of the national representative sample of
CWSs and NTNCWSs serving 10,000 or fewer people which must monitor for unregulated
contaminants (Assessment Monitoring, Screening Survey(s) and Index Systems) and all large systems
(systems serving greater than 10,000 people) which are required to monitor for Screening Survey
contaminants. A State Plan may be developed by a State's acceptance of EPA's representative sample
for that State, or by a State's selection of systems from a replacement list for systems specified in the
first list that are closed, are merged, or purchase water from another system. A State Plan also includes
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the process by which the State will inform each public water system of its selection for the plan and of
its responsibilities to monitor. A State Plan will also include the systems required to conduct Pre-Screen
Testing, selected from the State's designation of vulnerable systems. The State Plan may be part of the
Partnership Agreement (PA) between the State and EPA.
Stratified Random Sampling is a procedure to draw a random sample from a population that has been
divided into subpopulations or strata, with each stratum comprised of a population subset sharing
common characteristics. Random samples are selected from each stratum proportional to that stratum's
proportion of the entire population. The aggregate random sample (compiled from all the strata
samples) provides a random sample of the entire population that reflects the proportional distribution of
characteristics of the population. In the context of the UCMR, the population served by public water
systems was stratified by size (with size categories of 500 or fewer people served, 501 to 3,300 people
served, and 3,301 to 10,000 people served) and by water source type supplying the water system
(ground water or surface water). This stratification was done to ensure that systems randomly selected
as nationally representative sample systems would proportionally reflect the actual number of size and
water type categories nationally.
Testing means, for the purposes of the UCMR and distinct from Pre-Screen Testing, the submission
and/or shipment of samples following appropriate preservation practices to protect the integrity of the
sample; the chemical, radiological, physical and/or microbiological analysis of samples; and the
reporting of the sample's analytical results for evaluation. Testing is a subset of activities defined as
monitoring.
Unregulated contaminants means chemical, microbiological, radiological and other substances that
occur in drinking water or sources of drinking water that are not currently regulated under the federal
drinking water program. EPA has not issued standards for these substances in drinking water (i.e.,
maximum contaminant levels or treatment technology requirements). EPA is required by Congress to
establish a program to monitor for selected unregulated contaminants in public water systems to
determine whether they should be considered for future regulation to protect public health. The selected
contaminants are listed in §141.40(a)(3), Table 1, the UCMR List.
Vulnerable time (or vulnerable period) means the time (or, in some cases, the 3-month quarter) of the
year determined as the most likely to have the listed group of contaminants present at their highest
concentrations or densities in drinking water. The vulnerable determination, in the case of the UCMR, is
made by the EPA or by the State (under arrangement with the EPA) for a system, subset of systems, or
all systems in a State. The vulnerable determination is based on characteristics of the contaminants,
precipitation, system operations, and environmental conditions such as soil types, geology, and land
use. This determination does not indicate or imply that the listed contaminants will be identified in the
drinking water with certainty, but only that sampling conducted during the vulnerable period presumably
has the highest likelihood of identifying those contaminants in higher concentrations relative to other
sampling times of the year, if and when the contaminants occur.
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