[Federal Register: August 22, 2005 (Volume 70, Number 161)]
[Proposed Rules]
[Page 49093-49138]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr22au05-43]
[[Page 49094]]
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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Part 141
[Docket No. OW-2004-0001; FRL-7954-8]
RIN 2040-AD93
Unregulated Contaminant Monitoring Regulation (UCMR) for Public
Water Systems Revisions
AGENCY: Environmental Protection Agency.
ACTION: Proposed rule.
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SUMMARY: The Safe Drinking Water Act (SDWA), as amended in 1996,
requires the United States Environmental Protection Agency (EPA) to
establish criteria for a program to monitor unregulated contaminants
and to publish a list of contaminants to be monitored every five years.
EPA published such a list for the first Unregulated Contaminant
Monitoring Regulation cycle (i.e., UCMR 1) and a revised approach for
UCMR implementation in the Federal Register dated September 17, 1999.
UCMR 1 established a three-tiered approach for monitoring contaminants
based on the availability of analytical methods and laboratory capacity
considerations. Today's proposed regulation meets the SDWA requirement
to publish a listing of unregulated contaminants every five years.
Today's action proposes the design for the second UCMR cycle. EPA
is proposing to require monitoring of 26 chemicals using nine different
analytical methods. UCMR 2 monitoring is proposed to occur during 2007-
2011.This proposed action builds on the established structure of UCMR 1
and proposes some changes to the rule design. The primary changes to
UCMR 1 include: Redesign of the Screening Survey for List 2
contaminants to increase the statistical strength of the sampling
results by incorporating additional PWSs; updates to the lists of
contaminants to be monitored and the analytical methods approved to
conduct that monitoring; revisions to the ``data elements'' required to
be reported; and some revisions to the implementation of the monitoring
program to reflect ``lessons learned'' during UCMR 1. A systematic
procedure for the determination of a Minimum Reporting Level (MRL) is
also being proposed.
Implementation of today's proposed action would benefit the
environment by providing EPA and other interested parties with
scientifically valid data on the occurrence of these contaminants in
drinking water, permitting the assessment of the population potentially
being exposed and the levels of that exposure. These data are the
primary source of occurrence and exposure data for the Agency to
determine whether to regulate these contaminants.
DATES: Written comments must be postmarked by midnight, delivered by
hand, or electronically mailed on or before October 21, 2005.
ADDRESSES: Submit your comments, identified by Docket ID No. OW-2004-
0001, by one of the following methods:
• Federal eRulemaking Portal: http://www.regulations.gov. 
Follow the on-line instructions for submitting comments.
• Agency Web site: http://www.epa.gov/edocket. EDOCKET,
EPA's electronic public docket and comment system, is EPA's preferred
method for receiving comments. Follow the on-line instructions for
submitting comments.
• E-mail: OW-Docket@epa.gov.
• Mail: Send three copies of your comments and any
enclosures to: Water Docket, United States Environmental Protection
Agency, Mail Code 4101T, 1200 Pennsylvania Avenue, NW., Washington, DC
20460, Attention Docket ID No. OW-2004-0001. Commenters should use a
separate paragraph for each issue discussed. In addition, please mail a
copy of your comments on the information collection provisions to the
Office of Information and Regulatory Affairs, Office of Management and
Budget (OMB), Attn: Desk Officer for EPA, 725 17th St., NW.,
Washington, DC 20503.
• Hand Delivery: Deliver your comments to Water Docket, EPA
Docket Center, Environmental Protection Agency, Room B102, 1301
Constitution Ave., NW., Washington, DC, Attention Docket ID No. OW-
2004-0001. Such deliveries are only accepted during the Docket's normal
hours of operation, and special arrangements should be made for
deliveries of boxed information.
Instructions: Direct your comments to Docket ID No. OW-2004-0001.
EPA's policy is that all comments received will be included in the
public docket without change and may be made available online at http://
www.epa.gov/edocket, including any personal information provided,
unless the comment includes information claimed to be Confidential
Business Information (CBI) or other information whose disclosure is
restricted by statute. Do not submit information that you consider to
be CBI or otherwise protected through EDOCKET, http://www.regulations.gov,
or e-mail. The EPA EDOCKET and the http://www.regulations.gov
Web sites are ``anonymous access'' systems,
which means EPA will not know your identity or contact information unless
you provide it in the body of your comment. If you send an e-mail comment
directly to EPA without going through EDOCKET or http://www.regulations.gov,
your e-mail address will be automatically captured
and included as part of the comment that is placed in the public docket
and made available on the Internet. If you submit an electronic
comment, EPA recommends that you include your name and other contact
information in the body of your comment and with any disk or CD-ROM you
submit. If EPA cannot read your comment due to technical difficulties
and cannot contact you for clarification, EPA may not be able to
consider your comment. Electronic files should avoid the use of special
characters, any form of encryption, and be free of any defects or
viruses. For additional information about EPA's public docket visit
EDOCKET on-line or see the Federal Register of May 31, 2002 (67 FR
38102 (USEPA, 2002c)).
Docket: All documents in the docket are listed in the EDOCKET index
at http://www.epa.gov/edocket. Although listed in the index, some
information is not publicly available, i.e., CBI or other information
whose disclosure is restricted by statute. Certain other material, such
as copyrighted material, is not placed on the Internet and will be
publicly available only in hard copy form. Publicly available docket
materials are available either electronically in EDOCKET or in hard
copy at the Water Docket, EPA/DC, EPA West, Room B102, 1301
Constitution Avenue, NW., Washington, DC. This Public Reading Room is
open from 8:30 a.m. to 4:30 p.m., Monday through Friday, excluding
legal holidays. The telephone number for the Public Reading Room is
(202) 566-1744, and the Water Docket is (202) 566-2426.
FOR FURTHER INFORMATION CONTACT: Gregory Carroll, Technical Support
Center, Office of Ground Water and Drinking Water, United States
Environmental Protection Agency, Office of Water, 26 West Martin Luther
King Drive (MS 140), Cincinnati, OH 45268, telephone (513) 569-7948; or
e-mail at carroll.gregory@epa.gov. For general information, contact the
Safe Drinking Water Hotline. Callers within the United States may reach
the Hotline at (800) 426-4791. The Hotline is open Monday through
Friday, excluding legal holidays, from 9 a.m. to 5 p.m. eastern time.
SUPPLEMENTARY INFORMATION:
[[Page 49095]]
I. General Information
A. Does This Action Apply to Me?
Entities regulated by this action are public water systems (PWSs).
All large community and non-transient non-community water systems
serving more than 10,000 people will be required to monitor. A
community water system means a PWS which serves at least 15 service
connections used by year-round residents or regularly serves at least
25 year-round residents. Non-transient non-community water system means
a PWS that is not a community water system and that regularly serves at
least 25 of the same people over 6 months per year. Only a nationally
representative sample of community and non-transient non-community
systems serving 10,000 or fewer people will be required to monitor.
Transient non-community systems (i.e., systems that do not regularly
serve at least 25 of the same people over 6 months per year) will not
be required to monitor. States, territories, and tribes with primary
enforcement responsibility (primacy) to administer the regulatory
program for PWSs under the Safe Drinking Water Act (SDWA) may
participate in the implementation of the second cycle of the
Unregulated Contaminant Monitoring Regulation (i.e., UCMR 2) through a
Partnership Agreement. These Primacy agencies may choose to conduct
analyses to measure for contaminants in water samples collected for the
UCMR 2; in which case they will be regulated by this action. Regulated
categories and entities are identified in the following table.
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Examples of potentially
Category regulated entities NAICS \a\
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State, local, & tribal States, local and tribal 924110
governments. governments that
analyze water samples
on behalf of public
water systems required
to conduct such
analysis; states, local
and tribal governments
that directly operate
community and non-
transient non-community
water systems required
to monitor.
Industry......................... Private operators of 221310
community and non-
transient non-community
water systems required
to monitor.
Municipalities................... Municipal operators of 924110
community and non-
transient non-community
water systems required
to monitor.
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\a\ NAICS = North American Industry Classification System.
This table is not intended to be exhaustive, but rather provides a
guide for readers regarding entities likely to be regulated by this
action. This table lists the types of entities that the EPA is now
aware may potentially be regulated by this action. Other types of
entities not listed in the table could also be regulated. To determine
whether your facility is regulated by this action, you should carefully
examine the definition of PWS in Sec. 141.2 of Title 40 of the Code of
Federal Regulations, and applicability criteria in Sec. 141.40(a)(1)
and (2) of today's proposed action. If you have questions regarding the
applicability of this action to a particular entity, consult the person
listed in the preceding FOR FURTHER INFORMATION CONTACT section.
B. What Should I Consider as I Prepare My Comments for EPA?
1. Submitting Confidential Business Information
Do not submit this information to EPA through EDOCKET, http://
www.regulations.gov, or e-mail. Clearly mark the part or all
of the information that you claim to be confidential business information
(CBI). For CBI information in a disk or CD-ROM that you mail to EPA,
mark the outside of the disk or CD-ROM as CBI and then identify
electronically within the disk or CD-ROM the specific information that
is claimed as CBI. In addition to one complete version of the comment
that includes information claimed as CBI, a copy of the comment that
does not contain the information claimed as CBI must be submitted for
inclusion in the public docket. Information so marked will not be
disclosed except in accordance with procedures set forth in 40 CFR part 2.
2. Tips for Preparing Your Comments
When submitting comments, remember to:
• Identify the rulemaking by docket number and other
identifying information (subject heading, Federal Register date and
page number).
• Follow directions--The agency may ask you to respond to
specific questions or organize comments by referencing a Code of
Federal Regulations (CFR) part or section number.
• Explain why you agree or disagree; suggest alternatives
and substitute language for your requested changes.
• Describe any assumptions and provide any technical
information and/or data that you used.
• If you estimate potential costs or burdens, explain how
you arrived at your estimate in sufficient detail to allow for it to be
reproduced.
• Provide specific examples to illustrate your concerns, and
suggest alternatives.
• Explain your views as clearly as possible, avoiding the
use of profanity or personal threats.
• Make sure to submit your comments by the comment period
deadline identified.
Abbreviations and Acronyms
245-HBB 2,2',4,4',5,5'-hexabromobiphenyl
[mu]g/L Microgram per liter
ADI Acceptable daily intake
ASDWA Association of State Drinking Water Administrators
ATSDR Agency for Toxic Substances and Disease Registry
BDE-47 2,2',4,4'-tetrabromodiphenyl ether
BDE-99 2,2',4,4',5-pentabromodiphenyl ether
BDE-100 2,2',4,4',6-pentabromodiphenyl ether
BDE-153 2,2',4,4',5,5'-hexabromodiphenyl ether
CBI Confidential Business Information
CCL Contaminant Candidate List
CF Concentration fortified
CFR Code of Federal Regulations
CWS Community water system
DBP Disinfection Byproduct
DBPR Stage 1 Disinfection Byproducts Rule
DEA Desethylatrazine
DACT Diaminochlorotriazine or Desethyldesisopropylatrazine.
DIA Desisopropylatrazine
DQO Data quality objective
DSMRT Distribution system maximum residence time
EPA United States Environmental Protection Agency
EPTDS Entry point to the distribution system
ESA Ethane sulfonic acid
FACA Federal Advisory Committee Act
FR Federal Register
FS Field sample
g/kg Gram per kilogram
GWUDI Ground water under the direct influence of surface water
HRPIR Half range prediction interval of results
HSDB Hazardous Substances Database
[[Page 49096]]
IARC International Agency for Research on Cancer
ICR Information collection request
IDC Initial demonstration of capability
IRIS Integrated Risk Information System
LCMRL Lowest concentration minimum reporting level
LD50 Median lethal dose
LFSM Laboratory fortified sample matrix
LFSMD Laboratory fortified sample matrix duplicate
MCL Maximum contaminant level mg/kg Milligram per kilogram
mg/kg/day Milligram per kilogram per day mg/L Milligram per liter
MRL Minimum reporting level
NCOD National Drinking Water Contaminant Occurrence Database
NDBA N-nitroso-di-n-butylamine
NDEA N-nitroso-diethylamine
NDMA N-nitroso-dimethylamine
NDPA N-nitroso-di-n-propylamine
NMEA N-nitroso-methylethylamine
NPDWR National Primary Drinking Water Regulation
NPYR N-nitroso-pyrrolidine
NTNCWS Non-transient non-community water system
NTTAA National Technology Transfer and Advancement Act
OA Oxanilic acid
OMB Office of Management and Budget
ORD Office of Research and Development
PA Partnership agreement
PBB Polybrominated biphenyls
PBDE Polybrominated diphenyl ethers pH Negative log of the hydrogen ion
concentration
PIR Prediction interval of results
PT Proficiency testing
PWS Public water system
PWSID Public water system identification
QC Quality control
RDX Hexahydro-1,3,5-trinitro-1,3,5-triazine
RED Reregistration Eligibility Decision
RFA Regulatory Flexibility Act
RfD Reference dose
RPD Relative percent difference
SBA Small Business Administration
SDWA Safe Drinking Water Act
SRF State Revolving Fund
TBBPA Tetrabromobisphenol A
TDI Tolerable daily intake
TNT 2,4,6-trinitrotoluene
TRI Toxics Release Inventory
UCMR Unregulated Contaminant Monitoring Regulation
UMRA Unfunded Mandates Reform Act of 1995
USGS United States Geological Survey
USEPA United States Environmental Protection Agency
Table of Contents
I. General Information
A. Does This Action Apply to Me?
B. What Should I Consider as I Prepare My Comments for EPA?
1. Submitting Confidential Business Information
2. Tips for Preparing Your Comments
II. Statutory Authority and Background
A. What Is the Statutory Authority for UCMR?
B. How Does EPA Meet These Statutory Requirements?
C. How Are the Contaminant Candidate List, the National
Contaminant Occurrence Database, and the UCMR Interrelated?
III. Requirements of the Unregulated Contaminant Monitoring Program
A. What Priority Contaminants Were Selected for UCMR 2?
1. Compilation of Initial List of UCMR 2 Candidates
2. Establishing Priorities for UCMR 2
a. Health Effects Prioritization Approach.
b. Selections Based on UCMR 1 Reserved Contaminants List.
i. Alachlor ethane sulfonic acid (ESA) and Other Degradation
Products of Acetanilide Pesticides--List 2.
ii. Explosives--List 1.
c. Selections from UCMR 1 Contaminants List.
d. Selection of Emerging Contaminants.
i. Nitrosamines--List 2.
ii. Others Identified in CCL 1 Process and Recent Reviews of
Information on Emerging Contaminants--List 1.
3. Other Considerations in Selecting Contaminants
a. Triazine Chlorodegradates and Parent Compounds.
b. Other Contaminants Considered.
B. What Analytical Methods Will Be Used for Monitoring?
C. How Were These Analytical Methods Developed?
D. How Were Minimum Reporting Levels Determined?
E. How Will Laboratories Conduct UCMR Analyses?
1. Laboratory Approval Process for UCMR 2
a. Request to Participate.
b. Registration.
c. Application Package.
d. EPA Review of Application Package.
e. Proficiency Testing.
f. Written EPA Approval.
2. Quality Control Requirements
F. How Are Systems Selected for UCMR Monitoring?
1. How Are Systems Selected for Assessment Monitoring?
a. Original Assessment Monitoring Statistical Approach for UCMR 1.
b. Proposed Assessment Monitoring Statistical Approach for UCMR 2.
2. How Are Systems Selected for the Screening Survey?
a. Original Screening Survey Statistical Approach for UCMR 1.
b. Proposed Screening Survey Statistical Approach for UCMR 2.
3. What Is UCMR Pre-Screen Testing?
4. What Are the Other Applicability Considerations?
a. New Applicability Date.
b. Notice Regarding Changes to Applicability Required.
c. Definition of System Population.
G. When Must Monitoring Be Conducted?
1. Timing of Monitoring
2. Individual PWS Monitoring Schedules
H. Where Are Samples Collected?
I. What Is the States' Role in the UCMR Program?
1. State Participation in Partnership Agreements (PAs)
2. Activities To Be Included in the UCMR 2 PAs
a. Review and Revision of the Initial State Monitoring Plan.
b. Review and Approval of PWS Proposed Representative EPTDS.
c. Notification and Instructions for Systems.
3. What If States Do Not Participate in a PA?
J. What Are the Data Reporting Requirements?
1. What Information Is Required Prior to Monitoring?
a. Contact Information.
b. Sampling Location and Inventory Information.
c. Proposals for Ground Water Representative Sampling Locations.
2. When Must Monitoring Results Be Reported?
a. Large Systems.
b. Small Systems.
3. What Data Elements Are Required with the Monitoring Results?
a. New Data Elements.
b. Unchanged Data Elements.
c. Modified Data Elements.
d. Data Elements No Longer Reported.
K. Time Line of UCMR Activities
1. Assessment Monitoring
2. Screening Survey
IV. Cost and Benefits of Today's Proposed Action
V. Technical Corrections
VI. Statutory and Executive Order Reviews
A. Executive Order 12866: Regulatory Planning and Review
B. Paperwork Reduction Act
C. Regulatory Flexibility Act
D. Unfunded Mandates Reform Act
E. Executive Order 13132: Federalism
F. Executive Order 13175: Consultation and Coordination With
Indian Tribal Governments
G. Executive Order 13045: Protection of Children From
Environmental Health and Safety Risks
H. Executive Order 13211: Actions That Significantly Affect
Energy Supply, Distribution, or Use
I. National Technology Transfer and Advancement Act
J. Executive Order 12898: Federal Actions To Address
Environmental Justice in Minority Populations and Low-Income Populations
VII. Public Involvement in Regulation Development
VIII. References
PART 141--NATIONAL PRIMARY DRINKING WATER REGULATIONS
Sec. 141.24 Organic chemical, sampling and analytical requirements.
[[Page 49097]]
Sec. 141.35 Reporting for unregulated contaminant monitoring.
(a) General applicability.
(b) Reporting by all systems.
(1) Where to submit UCMR reporting requirement information.
(2) Contacting EPA if your system does not meet applicability
criteria or has status change.
(c) Reporting by large systems.
(1) Contact information.
(2) Sampling location and inventory information.
(3) Proposed ground water representative sampling locations.
(i) Qualifications.
(ii) Demonstration.
(iii) Approval.
(4) Contacting EPA if your PWS has not been notified of requirements.
(5) Notifying EPA if your PWS cannot sample according to schedule.
(6) Reporting monitoring results.
(i) Electronic reporting system.
(ii) Reporting schedule.
(7) Only one set of results accepted.
(8) No reporting of previously collected data.
(d) Reporting by small systems.
(1) Contact information.
(2) Reporting sampling information.
(e) Data elements.
Sec. 141.40 Monitoring requirements for unregulated contaminants.
(a) General applicability.
(1) Applicability to transient non-community systems.
(2) Applicability to community water systems and non-transient
non-community water systems.
(i) Large systems.
(ii) Small systems.
(3) Analytes to be monitored.
(4) Sampling requirements.
(i) Large systems.
(ii) Small systems.
(5) Quality control requirements.
(i) Sample collection/preservation.
(ii) Laboratory approval for Lists 1 and 2.
(iii) Minimum Reporting Level.
(iv) Laboratory fortified sample matrix and laboratory fortified
sample matrix duplicate.
(v) Detection Confirmation.
(vi) Method defined quality control.
(vii) Reporting.
(6) Violation of this rule.
(i) Monitoring violations.
(ii) Reporting violations.
(b) Requirements for State and Tribal participation.
(1) Governors' petition for additional contaminants.
(2) State-wide waivers.
(i) Application.
(ii) Approval.
List of Exhibits and Tables
Preamble
Exhibit 1: Proposed Contaminant List and Sampling Design
Exhibit 2: Summary of Proposed Major Changes to UCMR 1
Exhibit 3: Median Lethal Dose and Corresponding Toxicity Ranking
Exhibit 4: Comparison of Acetanilide Herbicides Use
Exhibit 5: Analytes Included in the Explosives Method (EPA 529)
Exhibit 6: Analytical Methods Proposed for UCMR 2 Monitoring
Exhibit 7: Approximate Sample Allocation for Assessment Monitoring:
Expected Number of Systems Selected by System Size and Water Source
Exhibit 8: UCMR 1 Design Allocation of Systems for Screening
Surveys, by Size Category
Exhibit 9: Allocation of Systems for Screening Survey, List 2 Contaminants
Exhibit 10: Time Line of UCMR Activities
Exhibit 11: Systems To Participate in UCMR 2 Monitoring
Exhibit 12: Number of Publicly- and Privately-Owned Systems Subject
to UCMR 2
Exhibit 13: EPA and Small Systems Costs for Implementation UCMR 2
Exhibit 14: UCMR 2 Relative Cost Analysis for Publicly-Owned Systems
(2007-2011)
Exhibit 15: UCMR 2 Relative Cost Analysis for Privately-Owned
Systems (2007-2011)
Sec. 141.35
Table 1. Unregulated Contaminant Monitoring Reporting Requirements
Sec. 141.40
Table 1. UCMR Contaminant List
Table 2. Monitoring Frequency by Contaminant and Water Source Types
Table 3. The Constant Factor (C) to be Multiplied by the Standard
Deviation to Determine the Half Range Interval of the PIR (Student's
t 99% Confidence Level)
II. Statutory Authority and Background
A. What Is the Statutory Authority for UCMR?
Section 1445(a)(2) of the Safe Drinking Water Act (SDWA), as
amended in 1996, requires that once every five years, beginning in
August 1999, the United States Environmental Protection Agency (EPA)
issue a new list of no more than 30 unregulated contaminants to be
monitored by PWSs, and that EPA enter the monitoring data into a
national contaminant occurrence database. EPA's UCMR program must
ensure that only a national representative sample of public water
systems (PWSs) serving 10,000 or fewer people will be required to
monitor; however, there are no such restrictions on the number of
systems serving more than 10,000 people. EPA must vary the frequency
and schedule for monitoring based on the number of systems served, the
source of supply, and the contaminants likely to be found.
B. How Does EPA Meet These Statutory Requirements?
To fulfill the initial SDWA requirements, EPA published ``Revisions
to the Unregulated Contaminant Monitoring Regulation for Public Water
Systems; Final Rule,'' on September 17, 1999 (64 FR 50556, (USEPA,
1999c)). Several supplemental rules were published to establish
analytical methods and to provide clarifications and refinements to the
initial rule: 65 FR 11372, March 2, 2000 (USEPA, 2000a); 66 FR 2273,
January 11, 2001 (USEPA, 2001a); and 67 FR 65888, October 29, 2002
(USEPA, 2002d).\1\ SDWA, as amended in 1996, requires that at least
once every five years EPA identify a list of no more than 30
unregulated contaminants to be monitored. Today's action fulfills this
statutory obligation, identifying 26 priority contaminants for
monitoring using nine proposed analytical methods. To comply with SDWA,
EPA has developed a proposed contaminant list (Exhibit 1) and sampling
design for UCMR 2 (2007-2011) with input from both stakeholders and an
EPA working group.
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\1\ Additional technical corrections to the rule, as well as
adjustments to the initial reporting process, were published
including: May 16, 2001 (66 FR 27215 (USEPA, 2001b)); September 4,
2001 (66 FR 46221 (USEPA, 2001d)); and March 12, 2002 (67 FR 11043
(USEPA, 2002b)). In total, these rules and revisions constitute the
``UCMR 1.'' This amendment to establish new contaminants for
monitoring during the second five-year cycle is referred to as ``UCMR 2.''
Exhibit 1.--Proposed Contaminant List and Sampling Design
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List 1. Assessment Monitoring
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1,3-dinitrobenzene........................ 2,4,6-trinitrotoluene (TNT).
2,2',4,4'-tetrabromodiphenyl ether (BDE- Dimethoate.
47).
2,2',4,4',5-pentabromodiphenyl ether (BDE- Hexahydro-1,3,5-trinitro-
99). 1,3,5-triazine (RDX).
2,2',4,4',5,5'-hexabromobiphenyl (245-HBB) Terbufos sulfone.
2,2',4,4',5,5'-hexabromodiphenyl ether Perchlorate.
(BDE-153).
[[Page 49098]]
2,2',4,4',6-pentabromodiphenyl ether (BDE- ............................
100).
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List 2. Screening Survey
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Acetochlor................................ Metolachlor OA.
Acetochlor ESA............................ N-nitroso-diethylamine
(NDEA).
Acetochlor OA............................. N-nitroso-dimethylamine
(NDMA).
Alachlor.................................. N-nitroso-di-n-butylamine
(NDBA).
Alachlor ESA.............................. N-nitroso-di-n-propylamine
(NDPA).
Alachlor OA............................... N-nitroso-methylethylamine
(NMEA).
Metolachlor............................... N-nitroso-pyrrolidine
(NPYR).
Metolachlor ESA........................... ............................
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The UCMR for the first cycle of monitoring (i.e., UCMR 1)
established a three-tiered approach for monitoring contaminants based
on the availability of analytical methods. Assessment Monitoring
contaminants on List 1 (UCMR 1) could be analyzed using analytical
methods that were in common use in drinking water laboratories.
Screening Survey contaminants on List 2 (UCMR 1) could only be analyzed
using newly developed analytical methods that were not in common use in
drinking water laboratories. Laboratory capacity to perform these
analyses was therefore limited. No analytical methods were available to
monitor for the Pre-Screen Survey contaminants on List 3 (UCMR 1),
although the regulation allowed for the possibility of such methods
becoming available during the cycle.
EPA has developed the design for the second UCMR cycle (i.e., UCMR
2). EPA is building upon the established structure of UCMR 1, and
proposing some changes to the rule design, based upon lessons learned
during the UCMR 1 cycle. The design of UCMR 2 is summarized below,
including a discussion of the changes proposed for UCMR 2, and the
reasons for those proposed changes.
Assessment Monitoring (i.e., List 1) is the largest in scope of the
three UCMR 2 monitoring components (or tiers). Under Assessment
Monitoring, List 1 contaminants, for which standard analytical methods
are available, are monitored to assess national occurrence in drinking
water. These are the priority contaminants for which analytical method
technologies are well established. EPA is proposing that Assessment
Monitoring be required for all large water systems (those serving more
than 10,000 people), and for a nationally representative sample of 800
small water systems (those serving 10,000 or fewer people), during a
continuous 12-month period during July 2007 through June 2010 quarterly
for surface water systems, and twice, at 6-month intervals for ground
water systems). Systems subject to UCMR 2 include community water
systems (CWSs) and non-transient non-community water systems (NTNCWSs),
except those systems that purchase all of their finished water from
another PWS.
EPA designed the sampling frame for the national sample of small
systems to ensure that UCMR 2 sampling results would yield a high level
of confidence and a low margin of error. To attain the representative
sample, EPA is proposing that small systems be stratified by water
source type (ground or surface water), service size category, and State
(each allocated a minimum of two systems). With monitoring data from
all large PWSs (a census of all 3,110 large systems) and a
statistically representative sample of 800 small PWSs (for a total of
approximately 3,910 systems), List 1 Assessment Monitoring provides
sample data suitable for national population exposure assessments.
The second tier of UCMR 2 is referred to as List 2 or Screening
Survey monitoring. List 2 contaminants are those for which analytical
methods have been recently developed, and for which the technologies
are not widely used and, therefore, laboratory capacity may be
insufficient to conduct the larger scale Assessment Monitoring. EPA is
proposing that a Screening Survey be conducted by approximately 320
PWSs serving more than 100,000 people (i.e., all systems in this
largest size category), by a randomly selected sample of 320 PWSs
serving between 10,001 and 100,000 people, and by 480 small PWSs.
Screening Survey systems will be required to monitor during a
continuous 12-month period during July 2007 through June 2009 quarterly
for surface water systems, and twice, at 6-month intervals, for ground
water systems). With a total of over 1,100 systems participating in the
Screening Survey, sufficient data will be generated to provide an
overall national estimate of population exposure.
The third tier of UCMR 2 is called Pre-Screen Testing. Pre-Screen
Testing is envisioned for use with methods that are in the early stages
of development, and/or methods that are very specialized or limited in
applicability. It is designed to be conducted by up to 200 PWSs that
would be identified by State agencies as vulnerable to the List 3
contaminants. This would be a targeted sampling to assess occurrence in
the most vulnerable settings, and could help to guide the next steps
for contaminant evaluation and methods development. EPA is not
proposing any Pre-Screen Testing in today's action.
C. How Are the Contaminant Candidate List, the National Contaminant
Occurrence Database, and the UCMR Interrelated?
The UCMR program was developed in coordination with the Contaminant
Candidate List (CCL) and the National Drinking Water Contaminant
Occurrence Database (NCOD). The CCL is a list of contaminants that are
not subject to any proposed or promulgated National Primary Drinking
Water Regulation (NPDWR), are known or anticipated to occur at PWSs,
and may require regulation under SDWA. The first CCL, published in
March 1998 (referred to as ``CCL 1''), identified 60 contaminants or
contaminant groups (63 FR 10274, March 2, 1998 (USEPA, 1998b)) that
were divided into categories to represent research and data needs for
each of the following: (1) Regulatory determination priorities; (2)
health effects research priorities; (3) treatment research priorities;
(4) analytical methods research priorities; and (5) occurrence
priorities. The data collected through the UCMR program is being stored
in the NCOD to facilitate analysis and review of contaminant
occurrence; to guide the conduct of the CCL process; and to support the
Administrator's determination to regulate a contaminant in the interest
of protecting public health, as required under SDWA section 1412(b)(1).
Results of the UCMR 1 monitoring can be
[[Page 49099]]
viewed by the public at EPA's UCMR Web site: http://www.epa.gov/
safewater/ucmr/data.html. The second CCL was published in February
2005 and carried over many of the unregulated contaminants from CCL 1, for
which research is ongoing (70 FR 9071, February 24, 2005 (USEPA, 2005).
III. Requirements of the Unregulated Contaminant Monitoring Program
EPA has developed, and is proposing in today's action, a revised
design for UCMR 2 based on experience with UCMR 1. In addition to
requesting comments on the list of UCMR 2 contaminants, EPA is also
requesting comments on the Agency's specification of minimum reporting
levels (MRLs) and the procedure to establish them. Other changes for
which EPA is requesting comment include modifications or clarifications
to the systems required to monitor, the timing and location of
monitoring, and the reporting process. Today's proposed modifications
to the rule also incorporate lessons learned during the course of UCMR
1 implementation. Throughout UCMR 1, EPA worked with States, regulated
PWSs, and analytical laboratories in addressing implementation and
regulatory requirements. EPA reviewed various aspects of the UCMR 1
program and identified several critical changes that will improve
implementation. The specific approach that EPA is proposing for UCMR 2,
along with the rationale for any changes, is described in this section.
Exhibit 2 provides a list of the substantive changes to UCMR 1
being proposed in today's action. EPA invites the public to comment on
these changes to the UCMR program. Instructions for submission of
public comments are provided in the ADDRESSES section of this preamble.
Key aspects of the UCMR program that remain the same include direct
implementation of the rule by EPA, the design of Assessment Monitoring,
and EPA funding for the small system testing (i.e., for those systems
serving 10,000 or fewer people).
Although EPA is republishing the entire text of 40 CFR 141.35 and
40 CFR 141.40 of today's action for readability purposes, EPA is not
reproposing for public comment aspects of the rule that are unchanged
from the 1999 UCMR 1. The unchanged aspects of UCMR 1 include: (1) The
design of Assessment Monitoring (for List 1 contaminants), except for
the elimination of Index Systems, and Pre-Screen Testing (for List 3
contaminants); (2) the frequency of sampling; (3) the requirement to
resample when a sampling error occurs; (4) use of the largest
concentration when duplicate samples are reported; (5) the requirements
for laboratories to enter monitoring data, and large PWSs to approve
and submit data using EPA's electronic data reporting system; (6)
reporting of PWS contacts; (7) the definition of violations; (8) the
opportunity for State and Tribes to enter into Partnership Agreements;
(9) the Governors' petition process; and (10) the State-wide waiver
provision. EPA is not seeking, and will not respond to comments on
parts of the UCMR that are unchanged under today's action.
Exhibit 2.--Summary of Proposed Major Changes to UCMR 1
------------------------------------------------------------------------
Change Preamble Rule
------------------------------------------------------------------------
New list of 26 priority Contaminants: Sec.
contaminants, and 9 analytical III.A.; 141.40(a)(3).
methods. Analytical
Methods: III.B.;
III.C.
Modified laboratory approval III.E.1........... Sec.
program. 141.40(a)(5)(ii)-
(vi).
QC requirements: Detection limit III.E.2........... Sec. Sec.
would be replaced by MRL; No 141.40(a)(5)(iii)
longer required to analyze a -(v).
field reagent blank or QC
sample.
Changes in timing for posting III.E.2; III.J.2.. Sec.
and approval of monitoring data. 141.35(c)(6)(ii);
Sec.
141.40(a)(5)(vii)
.
Elimination of Index systems.... III.F.1.b......... Sec.
141.40(a)(2)(ii)(
C).
More systems to monitor for III.F.2........... Sec.
Screening Survey. 141.40(a)(2)(i)(B
); Sec.
141.40(a)(2)(ii)(
B).
Screening Survey monitoring to III.F.2.b; III.K.2 Sec.
be conducted across 2 years. 141.40(a)(3).
Establishment of date for rule III.F.4........... Sec. 141.35(a);
applicability; Clarification of Sec. 141.40(a).
system population definition.
Large systems must submit III.J.1.a......... Sec.
contact and sampling location 141.35(b)(1).
information.
Large system monitoring will be III.G.2........... Sec.
scheduled by EPA with allowance 141.35(c)(5);
for systems to change schedule Sec.
if needed. 141.40(a)(4)(i).
All samples collected at EPTDSs; III.H; III.J.1.b.. Monitor at EPTDS
nitorsamines samples for PWSs and DSMRT
subject to Stage 1 D/DBP Rule locations: Sec.
collected at DSMRT and EPTDS 141.40(a)(3);
locations; Representative EPTDS Sec.
proposals by PWSs with multiple 141.40(a)(4)(i)(C
ground water EPTDSs. ); Sec.
141.40(a)(4)(ii)(
B).
EPTDS proposal:
Sec.
141.35(c)(3).
Changes to data elements........ III.J.3........... Sec. 141.35(e).
------------------------------------------------------------------------
Acronyms: QC = quality control; MRL = minimum reporting level; PWS =
public water system; EPTDS = entry point to the distribution system; D/
DBP Rule = Stage 1 Disinfectant/Disinfection Byproducts Rule; DSMRT =
distribution system maximum residence time; UCMR = Unregulated
Contaminant Monitoring Regulation.
A. What Priority Contaminants Were Selected for UCMR 2?
1. Compilation of Initial List of UCMR 2 Candidates
With public health protection as its top priority, EPA has drawn
upon several different sources in developing the proposed UCMR 2
contaminant list. In the early stages of list development, EPA began by
identifying a broad list of over 200 contaminants. This information and
rationale was first presented at a public stakeholder meeting held on
October 29, 2003, within a draft discussion document titled: ``UCMR 2:
Contaminant Selection Rationale'' (USEPA, 2003e). The following sources
were used to identify potential UCMR 2 contaminants:
• UCMR 1 ``reserved'' contaminants (CCL 1 occurrence
priorities): Includes those contaminants identified as priorities in
the September 1999 UCMR (64 FR 50556 (USEPA, 1999c)), but reserved for
later monitoring because methods were not yet available. By design,
most of the UCMR 1 contaminants were selected from the list of CCL 1
contaminants that required the
[[Page 49100]]
collection of additional occurrence data and for which analytical
methods were available (63 FR 10274 (USEPA, 1998b)).
• Other UCMR 1 contaminants: Includes several contaminants
that were monitored under UCMR 1 and were identified as potential UCMR
2 priorities because Screening Survey results indicate the need for
more information, or because improved analytical methods for these
contaminants have been developed since the last cycle.
• CCL 1 ``deferred pesticides'': Includes a list of priority
pesticides ranked by chemical properties, occurrence, and use that EPA
identified. EPA decided to ``defer'' certain pesticides for later
consideration pending further evaluation of these pesticides to
determine if they occur at levels of health concern (62 FR 52194,
October 6, 1997 (USEPA, 1997)). EPA plans to consider the deferred
pesticides in the context of an improved approach for selecting
contaminants for future CCLs. This will enable the Agency to consider
these contaminants in a consistent, reproducible manner with a wide
range of other contaminants.
• CCL 1 suspected endocrine disruptors: Includes a list of
chemicals that were suspected of having adverse effects on endocrine
function (62 FR 52194, October 6, 1997 (USEPA, 1997)) that EPA
identified during the development of CCL 1. For certain suspected
endocrine disruptors for which little information was available, EPA
decided to wait for further study to reconsider these contaminants in
the future. As with pesticides, EPA believes that suspected endocrine
disruptors should be considered in the context of an improved approach
for selecting contaminants for future CCLs. This enables the Agency to
use a more refined and improved approach in evaluating these contaminants.
• Other emerging contaminants: Includes additional
contaminants of concern based on current research on occurrence and
relative health effects risk factors, and whether the contaminants
could be identified by analytical methods used in measuring other
priority UCMR contaminants.
2. Establishing Priorities for UCMR 2
Of the 200-plus contaminants initially identified, EPA retained
only those contaminants that met the following criteria: (1) Pesticides
on the list must be currently registered for use in the United States;
(2) all contaminants must have an analytical reference standard (pure
compound) available; and (3) the analytical method must be available.
Based on these criteria, the list was reduced to approximately 127
contaminants.
EPA further prioritized this list of contaminants as follows. The
relative health effects screening was considered as part of EPA's
identification of contaminants for monitoring under UCMR 2 (the
relative effects screening and prioritization process is discussed and
explained in next section). Through this prioritization process, 26
contaminants have been identified for UCMR 2 monitoring. At the current
time, EPA does not expect to add contaminants to reach the statutory
maximum of 30 contaminants. However, if other emerging contaminant(s)
advance in importance during the first part of UCMR 2 monitoring, EPA
will consider an amendment that would add up to four additional
contaminants for monitoring in a later phase of the cycle. The
remainder of this section discusses the specific selection of
contaminants that EPA is proposing for UCMR 2 monitoring.
a. Health Effects Prioritization Approach. In identifying
contaminants for monitoring under the UCMR program, potential human
health effects are an important consideration. Therefore, after
compiling a broad list of potential UCMR contaminants, EPA's next step
was to develop a process to prioritize these contaminants by estimating
their relative adverse health effects. EPA first collected existing
health effects information, including Reference Dose (RfD), Tolerable
Daily Intake (TDI), Acceptable Daily Intake (ADI), Cancer Unit Risk,
Cancer Classification, and Median Lethal Dose (LD50). Using
this information, EPA developed a screening system to rank contaminants
into high, medium, and low relative priorities.
In developing the relative rankings, EPA recognized two tiers of
data for the assessment of non-cancer toxicity, based on applicability
to human health effects: (1) RfD (and its equivalents); and (2)
LD50. The RfD and equivalent measures such as TDI and ADI
are doses that are expected to have no measurable health effects on the
human population, including sensitive populations. These levels are
based on expert judgment of the available research data. The
LD50, on the other hand, is the result of observation of
effects in experimental studies (i.e., the concentration at which 50%
of experimental animals die) and has not been extrapolated for
application to human populations. Many compounds have measured
LD50 values, but significantly fewer have calculated RfDs.
In prioritizing compounds for inclusion in UCMR, EPA refers to RfD (and
equivalent data) as ``potency data'', while LD50 data are
referred to as ``toxicity data.''
As with the two tiers of data for non-cancer toxic effects, cancer
information is analogously divided into two tiers. The higher tier of
data, known as ``Unit Risk,'' represents the risk of developing cancer
from a given drinking water concentration. The second tier of data, the
``Cancer Classification,'' categorizes the likelihood of a compound
contributing to the human cancer burden and is a purely qualitative
measure. Thus, it is generally less informative than Unit Risk data.
RfDs were typically obtained from EPA's Integrated Risk Information
System (IRIS) or the Office of Pesticide Programs' Reregistration
Eligibility Decisions (REDs). The ADIs were typically identified
through the International Programme on Chemical Safety or the European
Agency for the Evaluation of Medicinal Products Web sites. TDIs were
identified through World Health Organization and the Netherlands
Institute of Health Sciences sources. If an RfD or equivalent could not
be identified, attempts were made to obtain an oral LD50 or
other relevant information from sources such as the Hazardous
Substances Database (HSDB) and primary literature. Cancer Unit Risk
information was typically obtained from IRIS or REDs, while cancer
classifications were found in IRIS, REDs, and from the International
Agency for Research on Cancer (IARC).
To develop a ranking for each contaminant, compounds with potency
data were assigned values from 1 to 10 based on equations derived
empirically from the distribution of RfDs for the compounds listed on
IRIS. Details concerning the derivations of these equations are
contained in a support document titled ``Estimating Potency Scores: An
Exercise'' (USEPA, 2004h). Contaminant prioritization estimates were
discussed at a public stakeholder meeting held on October 29, 2003; the
estimates are contained in an additional support document titled:
``UCMR 2: Contaminant Selection Rationale'' (USEPA, 2003e). One
equation was derived for RfD and equivalent data, and one for cancer
Unit Risk data. The distribution of RfD values was log-normally
distributed, and the following equation was used to score compounds:
Non-cancer risk = 10-(rounded log10 RfD + 7)
To score compounds on a relative scale of 1 to 10, EPA examined the
distribution of unit risks for the compounds found in the ``2002
Drinking Water Standards and Health
[[Page 49101]]
Advisories'' (USEPA, 2002a), and used the following equation:
Cancer Risk = 10-((rounded log10 10-\4\ cancer
risk) + 6)
Contaminants with resulting scores from each of these equations of 1-3
were considered relatively lower priority, those with scores of 4-6
were considered of medium relative priority, and scores of 7-10 were
considered to be of high relative priority. In the case of compounds
for which both cancer and non-cancer data were available, the data
associated with the highest relative score were used for prioritization.
Compounds with toxicity data were ranked by a separate system based
on LD50, and this ranking was modified by cancer
classification where possible. Exhibit 3 summarizes the criteria that
were used to rank compounds by LD50.
Exhibit 3.--Median Lethal Dose and Corresponding Toxicity Ranking
------------------------------------------------------------------------
Relative toxicity ranking LD50 data
------------------------------------------------------------------------
Very High................................. < =1 mg/kg \1\
High...................................... >1 mg/kg- <=50 mg/kg
Moderate.................................. >50 mg/kg- <=500 mg/kg
Slight.................................... >500 mg/kg- <=5 g/kg \2\
------------------------------------------------------------------------
\1\ mg/kg = milligram per kilogram.
\2\ g/kg = gram per kilogram.
Additionally, if a chemical meeting the ``slight'' criteria was
also noted as ``possibly carcinogenic to humans'' (Group 2B), the
chemical was moved up one level to ``moderate.'' For example,
2,2',4,4',5,5'-hexabromobiphenyl toxicity should be categorized as
slight based on an identified oral LD50 in rats of 21,500
milligrams per kilogram (mg/kg). However, because IARC categorized this
chemical as ``possibly carcinogenic to humans,'' it now is categorized
as moderate.
b. Selections Based on UCMR 1 Reserved Contaminants List. One of
EPA's priorities for UCMR 2 is to monitor for contaminants that were
identified as priorities for monitoring during UCMR 1, but were
``reserved'' because analytical methods were not available at the time.
Applying these criteria, two UCMR 1 ``reserved'' contaminants are
priorities for UCMR 2: alachlor ethane sulfonic acid (alachlor ESA)
(and other acetanilide pesticide degradation products) and hexahydro-
1,3,5-trinitro-1,3,5-triazine (RDX), an explosive. The first is a
contaminant group that is comprised of multiple contaminants, as
further discussed in this section. Both alachlor ESA (and other
degradation products of acetanilide pesticides) and RDX were included
on UCMR 1, List 2, but because the required analytical methods were not
available in time for UCMR 1 monitoring they were listed as ``reserved.''
i. Alachlor ethane sulfonic acid (ESA) and Other Degradation
Products of Acetanilide Pesticides--List 2.
Based on the rationale provided below, EPA is proposing that the
following six degradation products of acetanilide pesticides and their
parent compounds be part of the UCMR 2, List 2, Screening Survey
monitoring:
• Acetochlor
• Acetochlor ESA
• Acetochlor OA
• Alachlor
• Alachlor ESA
• Alachlor OA
• Metolachlor
• Metolachlor ESA
• Metolachlor OA
The proposed List 2 analytes include the ethane sulfonic acid (ESA)
and oxanilic acid (OA) degradation products of the three highest-use
parent acetanilide compounds: metolachlor, alachlor, and acetochlor
(see Exhibit 4). In addition, EPA is proposing that List 2 include the
parent compounds, acetochlor, alachlor and metolachlor, because one
possible option for regulating these compounds and their degradates
would be to establish maximum contaminant levels (MCLs) for the total
of each parent plus its respective metabolites.
There are a number of reasons why EPA has prioritized alachlor ESA
(and other degradation products of acetanilide pesticides) for
inclusion in UCMR 2 monitoring. This group of acetanilide degradation
products was originally listed under the CCL 1 occurrence priorities
and then included as part of UCMR 1, List 2 as ``reserved''; thus the
group is a top priority for UCMR 2 monitoring. In addition, ambient
water monitoring data indicate that occurrence of the acetanilide
degradation products (ESA and OA) is more widespread than that of the
parent compounds.
Inclusion of the parent acetanilides on List 2 monitoring will
potentially allow EPA to learn more about the extent of decomposition
of the parent compounds, and about levels of co-occurrence of the
parents and their degradation products. The parent acetanilides are
widely used herbicides applied for weed control on corn, soybean, and
other crops (see Exhibit 4). Acetochlor and metolachlor were both
included on the final CCL 1 priority list. Acetochlor was identified as
a CCL 1 occurrence priority, and was monitored under UCMR 1, List 1,
Assessment Monitoring. Metolachlor and its degradation products were
identified in the list of candidates for regulatory determination under
the CCL 1 prioritization process. However, EPA has since determined
that available health effects and occurrence information were
insufficient to support a regulatory determination.
Health effects studies have shown that chronic oral exposure to
parent acetanilide herbicides may have effects such as increased
salivation, decreased body weight, cellular/kidney/testicular
pathology, enlarged liver, and anemia in animal subjects (USEPA,
2003d). RfDs established by EPA for these parent herbicides are 0.01
milligrams per kilograms per day (mg/kg/day) for alachlor, 0.02 mg/kg/
day for acetochlor, and 0.15 mg/kg/day for metolachlor (USEPA, 2003d).
Based on animal studies, the carcinogenic potentials of the parent
acetanilide herbicides in humans are estimated to be: acetochlor and
metolachlor, ``possible carcinogen'' (59 FR 13654, March 23, 1994
(USEPA, 1994); 61 FR 10681, March 15, 1996 (USEPA, 1996a); and USEPA,
2003d); and alachlor, ``probable carcinogen'' (USEPA, 2004a). The NPDWR
for alachlor includes an maximum contaminant level goal of zero (due to
classification as a probable carcinogen) and an MCL of 0.002 milligrams
per liter (mg/L). EPA notes that alachlor is currently regulated under
the National Primary Drinking Water Standards. EPA is proposing the
collection of alachlor occurrence data in UCMR 2 concurrent with the
collection of data for the alachlor degradation products to determine
the degree of correlation between the parent compound and degradate
occurrence.
[[Page 49102]]
Exhibit 4.--Comparison of Acetanilide Herbicides Use \1\
--------------------------------------------------------------------------------------------------------------------------------------------------------
~1991-1995 ~1995-1998
~Early 1990s ~1992 annual ~1997 annual annual use annual use
Compound Year annual use use (million lb use (million lb (million lb (million lb
registered (million lb a.i.) -NCFAP a.i.) -NCFAP a.i.) -USGS a.i.) -USGS
a.i.) -EPA \2\ \3\ \4\ \4\
--------------------------------------------------------------------------------------------------------------------------------------------------------
Metolachlor....................................... 1976 59 59.4 67.3 57.9 66.9
(1987-1993)
Alachlor.......................................... 1969 29.3-44.6 51.6 15.2 25.7 15.1
(1993-1995)
Acetochlor........................................ 1994 -- -- 32.6 23.8 32.6
Propachlor........................................ 1964 2.1 4.3 0.9 3.9 0.9
(1987-1996)
Dimethenamid...................................... 1993 -- -- 6.0 2.6 6.0
Flufenacet........................................ 1998 -- -- -- -- --
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ ``--'' = substance not in use; a.i. = active ingredient.
\2\ EPA: http://cfpub.epa.gov/oppref/rereg/status.cfm?show=rereg
\3\ National Center for Food and Agricultural Policy (NCFAP):
http://www.ncfap.org/.
\4\ United States Geological Survey (USGS), national maps: http://ca.water.usgs.gov/pnsp/.
Note: Based on use amounts, EPA is proposing to monitor for the ESA and OA degradates of the three highest-use parent compounds: acetochlor, alachlor,
and metolachlor. In addition, EPA is proposing to monitor for acetochlor, alachlor, and metolachlor.
ii. Explosives--List 1.
Based on the rationale provided below, EPA is proposing that the
following three explosives compounds be part of the UCMR 2, List 1,
Assessment Monitoring:
• Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX)
• 2,4,6-trinitrotoluene (TNT)
• 1,3-dinitrobenzene
RDX was a CCL 1 occurrence priority and was included on UCMR 1,
List 2 as ``reserved,'' because analytical methods were not available
in time for rule implementation. EPA has since developed a method for
determining explosives in drinking water, thus allowing RDX to be
included under UCMR 2 monitoring. RDX is absorbed by oral, dermal, and
inhalation routes, and has been documented to cause central nervous
system effects such as seizures, disorientation, nausea, restlessness,
and lethargy. In addition, temporary anemia and leukocytosis after
ingestion of RDX has been observed (ATSDR, 1995b). EPA has derived a
chronic oral RfD for RDX of 0.0003 mg/kg/day, based on prostate
inflammation observed in rats in a two-year feeding study (USEPA,
2003d), and has classified RDX as a possible human carcinogen (Group
C), based on adenomas and carcinomas in female mice (USEPA, 2003d).
The ``explosives'' method can also be used to measure
concentrations of at least 13 other contaminants in the same compound
class (see Exhibit 5). A few that can be detected by this method were
already monitored under UCMR 1 (nitrobenzene, 2,4-dinitrotoluene, and
2,6-dinitrotoluene). Of the remaining contaminants analyzed with the
explosives method, the two with the highest relative health risk
rankings are 2,4,6-trinitrotoluene (TNT) (possible carcinogen) and 1,3-
dinitrobenzene (high relative health risk ranking). TNT and 1,3-
dinitrobenzene were also identified during the CCL 1 development
process on the working group's initial list of chemical contaminants
considered during the development of the draft CCL (62 FR 52194 at
52201, October 6, 1997 (USEPA, 1997)).
TNT has been detected in surface and ground water samples that were
collected near munitions facilities (ATSDR, 1995c). TNT typically co-
occurs with RDX (Burrows, 1982). EPA has classified TNT as a possible
human carcinogen (Group C) based on urinary bladder papilloma and
carcinoma observed in female rats and activity observed in Salmonella,
with and without metabolic activation (USEPA, 2003d). Based on TNT's
co-occurrence with RDX and its possible carcinogenicity, EPA is
proposing to include TNT for monitoring under UCMR 2.
1,3-dinitrobenzene is the only one of the explosive contaminants
considered for UCMR 2 to have been assigned a ``high'' relative health
risk ranking. The major clinical manifestations of oral exposure to
1,3-dinitrobenzene are hematologic, neurologic, endocrine, and
reproductive (ATSDR, 1995a). EPA has derived a chronic oral RfD for
this compound of 0.0001 mg/kg/day, based on increased weight of the
spleen (USEPA, 2003d). EPA believes that a likely route of exposure to
this compound is ingestion of contaminated drinking water (ATSDR,
1995a). Though no nationwide survey of occurrence has been conducted,
local water and soil studies provide some indication of 1,3-
dinitrobenzene occurrence in water. This compound has been detected in
water and soil at some Army ammunition plants, including detection in
ground water samples collected at an ammunition plant in Louisiana at
concentrations ranging from 1.2 to 195 micrograms per liter ([mu]g/L)
(ATSDR, 1995a). It has also been found in 12 of the 1,397 hazardous
waste sites on the National Priorities List; however, the total number
of sites tested for 1,3-dinitrobenzene is unknown (ATSDR, 1995a). In a
survey of ground water at 32 military installations, Walsh and
colleagues (USEPA, 1999a) detected 1,3-dinitrobenzene in 13 percent of
the 812 samples analyzed, with maximum concentrations of 8.7 [mu]g/L
and a median concentration of 0.78 [mu]g/L. As the most toxic of the
remaining explosives, EPA believes that 1,3-dinitrobenzene should be
included for monitoring under UCMR 2.
Exhibit 5.--Analytes Included in the Explosives Method (EPA 529)
------------------------------------------------------------------------
Relative health
Status Analyte rank \1\
------------------------------------------------------------------------
To be monitored under UCMR 2, hexahydro-1,3,5- M(C)
List 1. trinitro-1,3,5- M(C)
triazine (RDX). H
2,4,6-trinitrotoluene
(TNT).
1,3-dinitrobenzene...
[[Page 49103]]
Not Listed on CCL 1 and Not 1,3,5-trinitrobenzene M
included on UCMR 2. 2,4,6- M
trinitrophenylmethyl L(S)
nitramine (Tetryl). L(S)
2-amino-4,6- na
dinitrotoluene. M(M)
2-nitrotoluene....... L(S)
3,5-dinitroaniline... L(S)
3-nitrotoluene.......
4-amino-2,6-
dinitrotoluene.
4-nitrotoluene.......
Listed on CCL 1 and Monitored 2,4-dinitrotoluene... M
under UCMR 1. 2,6-dinitrotoluene... M
nitrobenzene......... M
------------------------------------------------------------------------
\1\ Relative Health Effects Rankings include: H = high priority based on
potency data (RfD or equivalent); M = medium priority based on potency
data (RfD or equivalent); M(C) = medium priority based on potency data
(cancer unit risk); M(M) = medium priority based on toxicity data
(contaminants with Moderate (M) toxicity are contained in this
category); L(S) = low priority based on toxicity data (contaminants
with Slight (S) toxicity are contained in this category); (na) = not
available.
c. Selections from UCMR 1 Contaminants List. Perchlorate, the salts
of which have a number of industrial applications, is primarily used in
the form of ammonium perchlorate, an oxidizer in solid fuels that are
used to power rockets, missiles, and fireworks. In 1997, a method was
developed which greatly lowered the method reporting limit (MRL) for
perchlorate from approximately 400 [mu]g/L, down to 4 [mu]g/L.
Subsequent monitoring found perchlorate in ground water and drinking
water at and above this level. Perchlorate was listed on EPA's CCL 1
out of concern for its occurrence and possible health effects and was
monitored under UCMR 1 Assessment Monitoring using Method 314.0 (USEPA,
1999e), with a MRL of 4 [mu]g/L.
EPA has improved the measurement capabilities of the perchlorate
methods. Recently developed methods (EPA Method 314.1 (USEPA, 2004b);
EPA Method 331.0 (USEPA, 2004c); and EPA Method 332.0 (USEPA, 2004d))
would allow collection of occurrence data with a substantially lower
reporting level than that specified during UCMR 1. In addition, since
publication of Method 314.0, new instrumentation has been made
commercially available that can, using this method, achieve the MRL of
0.57 [mu]g/L while meeting all of the quality control criteria of the
method. Since Method 314.0 permits flexibility in the eluent,
chromatographic column, and suppressor that are used, this new
instrumentation is allowed within the scope of the method. In this
notice, EPA will refer to Method 314.0 using this new instrumentation,
which can achieve the lower MRL as ``Method 314.0 enhanced.'' EPA
estimates that the average cost per sample for the new methods will be
about $150, compared to $75 per sample using the original Method 314.0.
The National Academy of Sciences (NAS) has recently completed a
review of available perchlorate health effects research. Perchlorate
can affect thyroid function because it is an ion that competitively
inhibits the transport of iodide into the thyroid. EPA has adopted the
NAS recommended reference dose of 0.0007 mg/kg per day, which
translates into a drinking water concentration of 24.5 [mu]g/L,
assuming a 70 kg body weight and 2 liters per day consumption. This
assumes, however, that 100% of exposure comes from drinking water. An
important step for EPA in considering whether to regulate perchlorate
in drinking water is to determine what portion of perchlorate exposure
may come from food and other sources and what portion from drinking
water (referred to as relative source contribution or RSC). A higher
exposure from food would mean a lower exposure from drinking water that
would still be consistent with the NAS recommended reference dose.
EPA is considering whether to collect additional data on drinking
water occurrence for perchlorate and if so, what method(s) and MRL
should be required. The Agency already has substantial occurrence data
for perchlorate from UCMR 1 using the original Method 314.0, which
allowed for measurement of perchlorate at concentrations down to 4
[mu]g/L. However, to inform future decisions regarding perchlorate, EPA
sees advantages to gathering additional data on perchlorate using the
newer methods. This additional information would provide a more
complete understanding of perchlorate's occurrence in drinking water.
For large systems, the new monitoring data would supplement data
already collected by these systems under UCMR 1, while for small
systems, a different random sample would be monitored. Further,
additional data at lower reporting levels could inform EPA's cost
estimates for a potential regulation by identifying drinking water
systems that may want, as a practical matter, to target a somewhat
lower level than the MCL in their control strategies. Finally, EPA
believes the new methods are more reliable and respond to comments
about the potential for false positives in the original Method 314.0.
At the same time, EPA recognizes that there are costs associated with
this additional monitoring, most of which would be incurred by drinking
water utilities and their customers. The cost of an additional round of
monitoring using the original method 314.0, with an MRL of 4 [mu]g/L,
would have been about half of the cost associated with the new methods
and lower MRL. EPA estimates the total cost for a second round of
perchlorate monitoring using the new methods to be $4.4 million over
five years, of which about $4 million would be incurred by large
drinking water utilities (an average of $1,200 per utility serving
10,000 persons or more), and $434,000 would be paid by EPA to analyze
samples for small systems. EPA requests comment on its proposal to
include perchlorate on the UCMR 2 list and on the appropriate methods
and reporting level.
d. Selection of Emerging Contaminants. Ongoing research has
identified other emerging contaminants that EPA believes are important
to include on the UCMR 2 Contaminant List.
i. Nitrosamines--List 2.
EPA is proposing to include the following six nitrosamines on the
UCMR 2, List 2, Screening Survey:
• N-nitroso-diethylamine (NDEA)
• N-nitroso-dimethylamine (NDMA)
• N-nitroso-di-n-butylamine (NDBA)
• N-nitroso-di-n-propylamine (NDPA)
[[Page 49104]]
• N-nitroso-methylethylamine (NMEA)
• N-nitroso-pyrrolidine (NPYR)
These six compounds are all considered by EPA to be probable human
carcinogens, and have been assigned high relative health effects
rankings (USEPA, 2003d). Animal studies provide evidence that many
nitrosamines, including all of those being proposed for UCMR 2, target
the liver when ingested orally. Nitrosamines also produce carcinogenic
effects in the esophagus, lung, nasal cavity, stomach, and elsewhere
when administered to animal subjects in drinking water; and many
nitrosamines target the liver when ingested orally (USEPA, 2003d).
Nitrosamines are produced in small amounts for research purposes, and
can form as intermediates and byproducts in chemical synthesis and the
manufacture of rubber, leather, and plastics. Four of the six proposed
nitrosamines (all except N-nitroso-methylethylamine and N-nitroso-
pyrrolidine) are listed on the Toxics Release Inventory (TRI),\2\ which
requires reporting of releases to the environment and other waste
management data. Nitrosamines can also form spontaneously in the
environment by the reaction of precursor amines with nitrosating agents
(nitrate and related compounds), or by the action of nitrate-reducing
bacteria. Common foods such as bacon and malt beverages can contain
nitrosamines, and there is evidence that nitrosamines can form in the
upper gastrointestinal tract (ATSDR, 1989). One nitrosamine, N-nitroso-
dimethylamine (NDMA), has been shown to form in chlorinated or
chloraminated water as a disinfection byproduct (DBP) (Choi et al.,
2002; Choi and Valentine, 2002a and 2002b; Mitch and Sedlak, 2002).
---------------------------------------------------------------------------
\2\ The Toxics Release Inventory (TRI) is a publicly available
EPA database that contains information on toxic chemical releases
and other waste management activities reported annually by certain
covered industry groups as well as Federal facilities. This
inventory was established under the Emergency Planning and Community
Right-to-Know Act of 1986 and expanded by the Pollution Prevention
Act of 1990. Generally, reporting is required for facilities in
covered industries with more than 10 full-time employees that
annually manufacture or process more than 25,000 pounds, or use more
than 10,000 pounds of a toxic chemical. More information is
available at the TRI Program Web site at: http://www.epa.gov/tri.
---------------------------------------------------------------------------
No nationwide data are available on nitrosamine occurrence in
United States waters. However, other studies give an indication of
likely occurrence. Since 1998, a number of NDMA detections have been
reported in California ground water (CAEPA, 2002) and finished drinking
water (CADHS, 2002) above the State's action level of 0.01 [mu]g/L. The
American Water Works Association Research Foundation recently
collaborated with the Water Environment Research Foundation to fund a
study on NDMA occurrence and behavior in raw, treated, and recycled
water; however, the final report is not yet available.
Given evidence of the toxic nature of nitrosamines, and their
potential occurrence in the environment (particularly NDMA in drinking
water as a DBP), EPA proposes to include these six contaminants on the
UCMR 2 list to learn more about their occurrence in drinking water.
ii. Others Identified in CCL 1 Process and Recent Reviews of
Information on Emerging Contaminants--List 1.
The following additional contaminants are proposed for UCMR 2, List
1, Assessment Monitoring based on evaluation of CCL 1 lists and methods
research.
• Dimethoate
• Terbufos sulfone
• Five flame retardants
Four polybrominated diphenyl ethers:
2,2',4,4'-tetrabromodiphenyl ether (BDE-47)
2,2',4,4',5-pentabromodiphenyl ether (BDE-99)
2,2',4,4',5,5'-hexabromodiphenyl ether (BDE-153)
2,2',4,4',6-pentabromodiphenyl ether (BDE-100)
One polybrominated biphenyl:
2,2',4,4',5,5'-hexabromobiphenyl (245-HBB)
There are a variety of reasons these contaminants are being
proposed for monitoring under UCMR 2. Terbufos sulfone was identified
through the CCL 1 development process as a deferred pesticide.
Dimethoate and the flame retardants are other contaminants that can be
measured by the same analytical method that is proposed for terbufos
sulfone. Terbufos sulfone and dimethoate have both been assigned
``high'' relative health effects rankings. Flame retardants are being
proposed by EPA for UCMR monitoring because of recent concern that
these have become widely occurring environmental contaminants (Darnerud
et al., 2001).
Although little is known regarding the health effects of terbufos
sulfone, EPA has established an RfD of 0.00005 mg/kg/day for the parent
compound, terbufos, based on a no observable adverse effect level for
plasma cholinesterase inhibition (USEPA, 1999b). Terbufos was monitored
under UCMR 1. Similar to the acetanilide degradates, however, EPA is
concerned that terbufos sulfone will be found more commonly in the
environment than its parent compound, based on the rapid decomposition
of the parent compound. Such rapid decomposition combined with concern
regarding the health effects of the parent compound terbufos justify
determining the occurrence of terbufos sulfone in drinking water.
The method EPA proposes for the analysis of terbufos sulfone can
measure many other contaminants (over 40). However, EPA used relative
health effects information to identify the highest priorities and to
comply with the statutory limit of 30 contaminants per UCMR monitoring
cycle. Of the remaining compounds that could be measured using gas
chromatography/mass spectrometry (GC/MS), the technology used in Method
527, dimethoate is being proposed for UCMR 2 monitoring because it
received a ``high'' ranking in EPA's health effects screening (USEPA,
2004h). Dimethoate is a TRI chemical that is produced for use on cotton
and other field crops, orchard crops, vegetable crops, in forestry, and
residential uses (USEPA, 1999f).
Dimethoate is rapidly absorbed, metabolized, and eliminated in rats
by oral or intravenous routes of administration (USEPA, 1999d). This
compound is a cholinesterase inhibitor and exerts its major toxic
effects through overstimulation of the nervous system (USEPA, 2003a).
Health effects include headache, weakness, coma, and death from
respiratory failure (HSDB, 1986). Dimethoate has been classified as a
``possible human carcinogen'' and EPA has established an RfD for this
compound of 0.0002 mg/kg/day (USEPA, 2003d). No national data is
available on the occurrence of dimethoate in waters of the United
States; however, two local studies provide an indication of limited
occurrence (USEPA, 1999f).
Synthetic flame retardants are among the other contaminants that
are measured by EPA Method 527. Flame retardants, such as
polybrominated diphenyl ethers (PBDEs) and polybrominated biphenyls
(PBBs), are added to plastics used in a variety of consumer products
such as computer monitors, televisions, textiles, and plastic foams.
Production of PBBs ended in 1976 in the United States following an
incident of significant agricultural contamination in 1973, but PBDEs
are still produced and used in the United States. Flame retardants have
been measured at low levels in air, sediments, animals, and food and
are believed to be widely occurring in the environment (Darnerud et
al., 2001). Recent data also indicate that total levels of flame
retardants are rapidly
[[Page 49105]]
increasing and that most people are exposed to low levels of these
contaminants (Hites, 2004). Findings from animal studies suggest
thyroid and liver effects, as well as possible reduced immune system
function and neurobehavioral alteration (ATSDR, 2002).
3. Other Considerations in Selecting Contaminants
EPA has identified nine analytical methods and 26 priority
contaminants for UCMR 2 monitoring. EPA considered many more
contaminants and methods for UCMR 2. Some of these contaminants were
given strong consideration but were not included as part of the
proposed UCMR 2, as discussed in the following section.
a. Triazine Chlorodegradates and Parent Compounds. While they are
not part of today's proposal, EPA invites comments on the possibility
of UCMR 2 monitoring for three triazine chlorodegradates and three of
their parent compounds, as follows:
• Desethylatrazine (DEA)
• Desisopropylatrazine (DIA)
• Diaminochlorotriazine (DACT) \3\
• Atrazine
• Simazine
• Propazine
---------------------------------------------------------------------------
\3\ Another commonly used name for DACT is
desthyldesisopropylatrazine.
---------------------------------------------------------------------------
EPA is interested in these chlorodegradates and three parent
compounds because the Agency is conducting a cumulative risk assessment
for the chlorodegradates as a group with atrazine, simazine and
propazine. The ``triazines and degradation products of triazines'' are
also CCL 1 contaminants.
Atrazine and simazine are regulated contaminants with MCLs of 3
[mu]g/L and 4 [mu]g/L, respectively. Propazine was a cancelled
pesticide based on its contamination of ground water but was
reintroduced for greenhouse uses only (it is now used on container
grown ornamentals in greenhouses); however, EPA is currently evaluating
a proposal to use propazine for the control of broadleaf weeds and
annual grasses in sorghum, a use previously listed on labels, but
voluntarily removed prior to 1990. Propazine was identified through the
CCL 1 development process as a deferred pesticide. A fourth triazine,
cyanazine, is not being addressed since its production and use were
phased out between 1996 and 2002.
Atrazine, simazine and propazine metabolize into various
chlorodegradation products of which Desethylatrazine (DEA),
Desisopropylatrazine (DIA), and Diaminochlorotriazine (DACT) are the
most significant. Atrazine forms all three of these chlorodegradates;
whereas, simazine, a diethyl analogue of atrazine, degrades to DIA and
DACT, and propazine, a diisopropyl analogue of atrazine, degrades to
DACT and DEA (Scribner et al., 2000). In addition, ambient water
monitoring data indicate that concentrations of these chlorodegradates
in water may be equal to, or even exceed, concentrations of atrazine
(and other parent compounds) (Scribner et al., 2000). While atrazine
and simazine are already regulated under the National Primary Drinking
Water Standards, EPA is considering UCMR monitoring for these parent
compounds concurrent with the collection of UCMR data for their
degradation products to determine the degree of correlation between the
occurrence of the parents and their degradation products.
EPA is currently developing a liquid chromatography/tandem mass
spectrometry (LC/MS/MS) method to analyze the parent triazines and
these chlorodegradates and expects that method to be available within
the next year. Depending on method development progress, EPA's further
assessment of the relative health effects of triazine degradates, and
comments received pursuant to today's proposed regulation, EPA may
consider adding triazines and degradates to the Screening Survey for
UCMR 2. Because only 30 analytes can be monitored during any one cycle
of the UCMR program, EPA recognizes that the addition of the triazines
and degradates to the Screening Survey may require the elimination of
other contaminants from UCMR 2. Contaminants that EPA is considering in
this regard may include one or more of the acetanilide pesticides or
degradation products (see section III.A.2.b.i), which are also measured
using an LC/MS/MS method. EPA invites comments on whether the
concurrent use of two similar methods may strain laboratory capacity.
b. Other Contaminants Considered. EPA had originally identified
over 200 contaminants as potential UCMR 2 priorities. Many were
eliminated based on specific criteria, as discussed in section III.A.2
of this action (including the requirements that pesticides must be
registered, reference standards must be available, and the analytical
method must be available to include in this proposed action). Those
eliminated or deferred due to other considerations are worthy of
further mention because of particular public interest. These
contaminants, and the reasons for their exclusion from today's proposed
action, include:
• Aeromonas: The UCMR 1 Screening Survey for Aeromonas
indicates that it warrants further evaluation. Data analyzed thus far
have identified Aeromonas at the genus level. Identification and
analysis of pathogenic strains for some of the small system samples is
underway but have not been completed as of the publication of this
proposed action. EPA believes that it is premature to propose
additional monitoring for Aeromonas. The evaluation of the speciation
of the isolates collected during UCMR 1, and the development of a more
routine and affordable species-specific method will support future
monitoring, if deemed appropriate.
• Cyanotoxins: While extensive analytical methods
development was conducted for one class of cyanobacteria toxins,
microcystins, in preparation for UCMR 2, adequate accuracy in surface
waters with total organic carbon levels of 2 mg/L and higher has not
yet been demonstrated. Two other cyanotoxins--anatoxin A, and
cylindrospermopsin--were included in the initial method development.
However, these were not compatible with the microcystin method being
developed, and other analytical methods will not be available in time
for UCMR 2 monitoring. Therefore, none of the cyanobacteria toxins are
being proposed for monitoring at this time. However, further analytical
methods development is continuing.
• Diuron: EPA considered whether Diuron would be a good
candidate to include in UCMR 2 Assessment Monitoring. Interim
monitoring results from the UCMR 1 Screening Survey have shown only one
detection of Diuron. Because this suggests very low occurrence in
drinking water, and because other contaminants are of greater relative
health effects concern, Diuron was not established as a priority
contaminant for UCMR 2 monitoring.
• Ethylene thiourea: While extensive analytical methods
development was conducted for ethylene thiourea in preparation for UCMR
2, reproducible recoveries have not yet been demonstrated. Therefore,
ethylene thiourea is not being proposed for monitoring at this time.
However, further analytical methods development is continuing.
• Mirex and TBBPA: Mirex was considered for UCMR 2
monitoring and was found to have a ``high'' relative health effects
ranking. Though it can be measured using the GC/MS method, Mirex has
not been used or produced in the United States since 1978. For this
[[Page 49106]]
reason, EPA has not included Mirex on the list of UCMR 2 priorities. In
addition, tetrabromobisphenol A (TBBPA), a brominated flame retardant,
was initially considered for inclusion on the list of contaminants to
be measured using GC/MS, EPA Method 527. However, TBBPA was found to be
incompatible with this method, and is therefore not included on the
list of UCMR 2 priorities.
B. What Analytical Methods Will Be Used for Monitoring?
The analytical methods that are being proposed for use in UCMR 2
and the contaminants that they measure are listed in Exhibit 6. EPA has
conducted both literature searches, as well as searches of available
consensus method organizations' publications for additional analytical
methods that could be used to support this monitoring. No such
additional methods were identified that meet the requirements of this
proposed action. All of the analytical methods proposed use either mass
spectrometry or tandem mass spectrometry (i.e., MS/MS) for the
detection of the analytes, with the exception of EPA Methods 314.0
enhanced and 314.1 (USEPA, 1999e and USEPA, 2004b, respectively).
EPA is proposing that all positive occurrences of perchlorate
(i.e., those at or above the MRL of 0.57 [mu]g/L), determined using the
Methods 314.0 enhanced or 314.1, must be confirmed through the use of a
second chromatographic column, as detailed in Method 314.1, or by MS or
MS/MS, using EPA Methods 331.0 or 332.0 (USEPA, 2004c and USEPA, 2004d,
respectively). EPA requests comment on the level at which positive
occurrences of perchlorate must be confirmed.
By design of the UCMR program, UCMR contaminants measured by
analytical techniques that are commonly available are assigned to List
1, Assessment Monitoring (EPA Methods 314.0 enhanced, 314.1, 331.0,
332.0, 527, and 529). While most of these are newly developed
analytical methods, the techniques they employ are in common use by
drinking water laboratories. These methods are assigned to Assessment
Monitoring because this is the largest component of UCMR, with
monitoring conducted by a sample of 800 systems serving 10,000 or fewer
people, and all systems serving more than 10,000 people (approximately
3,200 systems).
UCMR contaminants that are measured by analytical methods that have
been recently developed and use techniques that are not commonly used
in drinking water analyses are assigned to the List 2, Screening
Survey. These less common methods are generally more appropriate for
the Screening Survey because fewer laboratories will be capable of
conducting such analyses, and the smaller scale monitoring under the
Screening Survey should reduce potential laboratory capacity issues.
However, in order to monitor for the parent compounds of the
acetanilide degradates, Method 525.2, which is commonly used for
regulated monitoring, is also being included for List 2 monitoring.
During the Screening Survey, a sample of 800 systems serving 100,000 or
fewer people and all (approximately 320) systems serving more than
100,000 people would monitor. Exhibit 6, summarizes the UCMR 2 methods
and associated contaminants.
Exhibit 6.--Analytical Methods Proposed for UCMR 2 Monitoring
------------------------------------------------------------------------
Analytical method \1\ Contaminant UCMR 2 List
------------------------------------------------------------------------
EPA Method 314.0 enhanced Perchlorate......... List 1, Assessment
(IC/Conductivity). Monitoring: 1
contaminant.
EPA Method 314.1 (IC/
Conductivity)
EPA Method 331.0 (LC/MS or
LC/MS/MS)
EPA Method 332.0 (IC/MS or
IC/MS/MS)
EPA Method 527 (SPE/GC/MS).. 2,2',4,4'-
tetrabromodiphenyl
ether (BDE-47).
2,2',4,4',5-
pentabromodiphenyl
ether (BDE-99).
2,2',4,4',5,5'-
hexabromobiphenyl
(245-HBB).
.................... List 1, Assessment
Monitoring: 7
contaminants.
2,2',4,4',5,5'-
hexabromodiphenyl
ether (BDE-153).
2,2',4,4',6-
pentabromodiphenyl
ether (BDE-100).
Dimethoate..........
Terbufos sulfone....
EPA Method 529 (SPE/GC/MS).. 1,3-dinitrobenzene.. List 1, Assessment
2,4,6- Monitoring: 3
trinitrotoluene contaminants.
(TNT).
Hexahydro-1,3,5-
trinitro-1,3,5-
triazine (RDX).
EPA Method 521 (SPE/GC/CI/MS/ N-nitroso- List 2, Screening
MS). diethylamine (NDEA). Survey: 6
N-nitroso- contaminants.
dimethylamine
(NDMA).
N-nitroso-di-n-
butylamine (NDBA).
N-nitroso-di-n-
propylamine (NDPA).
N-nitroso-
methylethylamine
(NMEA).
N-nitroso-
pyrrolidine (NPYR).
EPA Method 535 (SPE/HPLC/MS/ Acetochlor ESA...... List 2, Screening
MS). Acetochlor OA....... Survey: 6
Alachlor ESA........ contaminants.
Alachlor OA.........
Metolachlor ESA.....
Metolachlor OA......
EPA Method 525.2 (SPE/GC/MS) Acetochlor.......... List 2, Screening
Alachlor............ Survey: 3
Metolachlor......... contaminants.
[[Page 49107]]
Total of 26 UCMR 2
contaminants
------------------------------------------------------------------------
\1\ EPA Method 314.0: Determination of Perchlorate in Drinking Water
Using Ion Chromatography (USEPA, 1999e). Note: Since Method 314.0 was
published in 1999 to support UCMR 1 monitoring at an MRL of 4.0 [mu]g/
L, new instrumentation has been made commercially available from
Metrohm Peak that can, using this method, achieve the MRL of 0.57
[mu]g/L as called for by this proposed regulation, while meeting all
of the quality control criteria of the method. Because enhanced Method
314.0 permits flexibility in the eluent, chromatographic column, and
suppressor that are used, this new instrumentation would be permitted
within the scope of the original method. Therefore, enhanced Method
314.0 is being proposed for use in this regulation.
EPA Method 314.1: Determination of Perchlorate in Drinking Water Using
Inline Column Concentration/Matrix Elimination Ion Chromatography with
Suppressed Conductivity Detection (USEPA, 2004b).
EPA Method 331.0: Determination of Perchlorate in Drinking Water by
Liquid Chromatography Electrospray Ionization Mass Spectrometry
(USEPA, 2004c)
EPA Method 332.0: Determination of Perchlorate in Drinking Water Using
Ion Chromatography with Suppressed Conductivity and Electrospray
Ionization Mass Spectrometry (USEPA, 2004d).
EPA Method 521: Determination of Nitrosamines in Drinking Water by Solid
Phase Extraction and Capillary Column Gas Chromatography with Large
Volume Injection and Chemical Ionization Tandem Mass Spectrometry (MS/
MS) (USEPA, 2004e).
EPA Method 525.2: Determination of Organic Compounds in Drinking Water
by Liquid-Solid Extraction and Capillary Column Gas Chromatography/
Mass Spectrometry (USEPA, 1995).
EPA Method 527: Determination of Selected Pesticides and Flame
Retardants in Drinking Water by Solid Phase Extraction and Capillary
Column Gas Chromatography/Mass Spectrometry (GC/MS) (USEPA, 2004f).
EPA Method 529: Determination of Explosives and Related Compounds in
Drinking Water by Solid Phase Extraction and Capillary Column Gas
Chromatography/Mass Spectrometry (GC/MS) (USEPA, 2003c).
EPA Method 535, Revision 1.1: Measurement of Chloroacetanilide and Other
Acetamide Herbicide Degradates in Drinking Water by Solid Phase
Extraction and Liquid Chromatography/Tandem Mass Spectrometry (LC/MS/
MS) (USEPA, 2004g).
C. How Were These Analytical Methods Developed?
EPA developed the proposed analytical methods at two laboratories
in Cincinnati, Ohio: The Office of Water, Office of Ground Water and
Drinking Water's Technical Support Center and the Office of Research
and Development, National Exposure Research Laboratory's Chemical
Exposure Research Branch. Additional methods development support was
provided by: The Dionex Corporation, Sunnyvale, California; Metrohm
Peak, Houston, Texas; Office of Research and Development's Ground Water
and Ecosystems Restoration Division, Ada, Oklahoma; and EPA's Region 1,
New England Laboratory, Chelmsford, Massachusetts.
Extensive method testing was performed for each of the analytical
methods developed for this proposed action. Each step of each method
was tested for robustness and to evaluate the amount of user
flexibility that could be permitted for that step. Additional details
concerning this testing, beyond that included in each method, are
contained in methods research reports. These reports are available for
each newly developed method being proposed in the docket for this
action. However, no such report is available for Method 314.0, which
was developed for UCMR 1, or for Method 525.2, which was developed in
1995. Wherever feasible, EPA permitted the maximum user flexibility
commensurate with maintaining data quality. In addition, each method
was tested in a second or, for some methods, a third laboratory. These
second and third laboratory studies were designed to test the precision
and accuracy of each method in reagent water and in different drinking
water matrices, as well as the ease of use of the method and the
clarity of the written instructions of the method. Reports containing
the data developed during these second and third laboratory studies are
also available in reports included in the docket for this action for
each newly developed method being proposed. Similar data was generated
in to support the proposed action of Method 314.0. These data are also
included in the docket for review.
The methods developed for UCMR 2 analyses were peer reviewed in
accordance with the Agency's peer review guidelines detailed in the
``Science Policy Council Handbook, Peer Review'' (USEPA, 2000b).
Methods 314.0 and 525.2, which were developed prior to 2000, were peer
reviewed using similar criteria.
D. How Were Minimum Reporting Levels Determined?
Minimum Reporting Levels (MRLs) represent an estimate of the lowest
concentration of a compound that can be quantitatively measured by a
group of experienced drinking water laboratories. EPA is proposing that
all laboratories providing UCMR 2 analysis be required to demonstrate
their ability to measure each compound at the MRL proposed for that
compound in Sec. 141.40(a)(3) of today's action. EPA has developed a
protocol for developing MRLs based on Lowest Concentration MRLs
(LCMRLs) that were determined by each laboratory that developed or
subsequently tested the methods listed in today's action. LCMRLs
represent the lowest concentration of a compound that can be
quantitatively determined in each individual laboratory. EPA invites
comments on the LCMRL/MRL approach and notes that in a related action,
EPA's Office of Water is about to begin an evaluation of a wide range
of detection and quantitation approaches under the Federal Advisory
Committee Act (FACA) process. EPA expects to consider the comments and
feedback from this FACA process to the extent possible in the
development of the UCMR 2 final rule.
MRLs have previously been determined by analytical laboratories
using expert professional judgement, but standard criteria for MRL
determination have not been established. In both the Information
Collection Rule (61 FR 24354, May 14, 1996 (USEPA, 1996b)) and UCMR 1,
EPA specified MRLs and a requirement for recovery at the MRL so that
data quality was documented daily. In the interest of greater
consistency, EPA has developed a statistical protocol for single-
laboratory determinations of LCMRLs using linear regression and
prediction intervals. This approach, described in detail in the report
titled ``Statistical Protocol for the Determination of the Single-
Laboratory Lowest Concentration Minimum Reporting Level (LCMRL) and
Validation of the Minimum Reporting Level (MRL)'' (USEPA, 2004j), has
been evaluated through expert peer review conducted in accordance with
the Agency's formal peer review process and through the performance of
a pilot-scale interlaboratory study. The
[[Page 49108]]
proposed protocol is available to the public, and can be found at:
http://www.epa.gov/safewater/methods/sourcalt.html.
Details of this pilot-scale interlaboratory study are contained in
a report titled ``Evaluation of the Lowest Concentration Minimum
Reporting Level (LCMRL) and the Minimum Reporting Level (MRL) Primary
Analyte Analysis'' (USEPA, 2004i). An evaluation of the procedures used
in this proposed action, and other tested procedures to determine MRLs
from LCMRLs, are detailed in Chapter 4 of the report. The guidelines
and procedures for using LCMRLs in establishing MRLs for UCMR 2 are
described later in this section.
As proposed, the MRL would be the lowest analyte concentration that
meets Data Quality Objectives (DQOs) as presented in Sec. 141.40(a)(5)
of today's proposed rule, and represents the lowest concentration for
which future recovery is predicted to fall, with high confidence (99
percent), between 50 percent and 150 percent. MRLs would be applicable
to all laboratories that perform the analysis of drinking water samples
as part of UCMR 2. All UCMR 2 laboratories would be required to
validate their performance at or below the MRLs before initiating any
analyses. This proposal does not require that measurements observed at
concentrations below the MRL be reported. In other programs, such
reporting may be appropriate. The appropriateness of reporting
measurements below the MRL, is generally dependent upon the objectives
of a study and is not addressed in this proposed action.
To determine the MRLs listed in today's action, each laboratory
that conducted the primary analytical method development, or second or
third laboratory studies, determined LCMRLs as detailed in the
statistical protocol (USEPA, 2004g). The mean of these LCMRL values was
calculated for each analyte. In cases where data from three or more
laboratories were available, three times the standard deviation of the
LCMRLs was added to the mean of the LCMRLs, to establish the MRL. In
cases where data from two laboratories were available, three times the
difference of the LCMRLs was added to the mean of the LCMRLs. In
statistical theory (Chebyshev's Inequality), three standard deviations
around the mean incorporates the vast majority (at least 88.9 percent)
of the data points. In the case where there are only two laboratories,
the difference serves as a surrogate for the standard deviation due to
the uncertainty in the estimate of the standard deviation with only two
data points. The MRL for each analyte was determined by then rounding
this number to two significant digits.
Note that Method 525.2 was published before the LCMRL protocol was
developed. Therefore, no LCMRL data are available for the analytes
being determined using this method. The MRLs for acetochlor, alachlor,
and metolachlor were determined using the same procedure used in UCMR
1, i.e., multiplication of the highest individual laboratory method
detection limit in the method by a factor of 10. Note also that there
is a single MRL for perchlorate, although there are four methods
approved for UCMR analyses. The value of 0.57 [mu]g/L is a mid-range
value (and the MRL determined for Method 332.0) that is easily
achievable for Methods 314.1, 331.0, and 332.0; and slightly more
difficult to achieve using Method 314.0.
LCMRLs were calculated by selected laboratories during analytical
method development. There is no requirement for laboratories that are
analyzing samples under the UCMR to determine LCMRLs. The procedure for
LCMRL determination includes the following:
• Calibration curve analysis;
• Replicate sample analysis requirements;
• Linear regression procedures; and
• Outlier evaluation.
The validation of laboratory performance at or below the MRL would
be required to be performed by all laboratories that analyze samples
under UCMR 2. Validation would consist of two procedures:
• As part of the Initial Demonstration of Capability (IDC)
for each analytical method, each laboratory would need to process seven
replicate samples, spiked at or below the MRL, through the entire
method procedure (i.e., including extraction and with all
preservatives, where applicable). This step would need to be performed
for each analyte. Laboratories would be required to demonstrate that,
based on the results of the seven replicates, their predicted range of
results will fall, with 99 percent confidence, within 50 percent to 150
percent recovery, inclusive.
• During sample analysis, laboratories would need to run a
daily check sample to demonstrate that, at or below the MRL for each
analyte, the measured recovery is within 50 percent to 150 percent,
inclusive. The results for any analyte for which 50 percent to 150
percent recovery cannot be demonstrated during the daily check would
not be valid. Laboratories may elect to re-run the daily performance
check sample if the performance for any analyte or analytes cannot be
validated. If the performance for these analytes is validated, then the
laboratory performance would be considered validated. If not, or as an
alternative to analysis of a second check sample, the laboratory may
re-calibrate and repeat the performance validation process for all
analytes.
Further details regarding these procedures are available through
EPA's UCMR Web site (http://www.epa.gov/safewater/ucmr/
ucmr2/index.html) in a document titled ``UCMR 2 Laboratory Approval
Requirements and Information Document'' (USEPA, 2004k).
E. How Will Laboratories Conduct UCMR Analyses?
All laboratories conducting analyses under this regulation must be
approved by EPA to perform those analyses. Laboratories seeking
approval must provide EPA with data that demonstrates their successful
completion of an IDC as outlined in each method, verification of
successful performance at the MRLs as specified in today's action, and
successful participation in an EPA Proficiency Testing (PT) program for
the analytes of interest. On-site audits of selected candidate
laboratories may be conducted. Details of the EPA laboratory approval
program are contained in the technical manual titled: ``UCMR 2
Laboratory Approval Requirements and Information Document'' (USEPA,
2004k). This document will be available on the electronic docket at:
http://www.epa.gov/edocket/; or through EPA's UCMR Web site:
http://www.epa.gov/safewater/ucmr/ucmr2/index.html. In addition, EPA
may dition, EPA may participating/approved laboratories.
1. Laboratory Approval Process for UCMR 2
The UCMR 2 laboratory approval program is designed to assess and
confirm the capability of laboratories to perform analyses using the
methods listed in Table 1 of today's proposed rule, in Sec.
141.40(a)(3). With the exception of EPA Method 525.2, the UCMR 2
methods do not currently have an established certification program.
Applicant laboratories that are already approved by their State or
primacy entity to conduct drinking water analyses using Method 525.2
will still need to perform the UCMR approval steps, including the
related PT evaluation. The UCMR 2 laboratory approval process is
designed to assess whether laboratories meet the required equipment,
laboratory performance, and
[[Page 49109]]
data reporting criteria described in today's action. This evaluation
program is voluntary in that it only applies to laboratories intending
to analyze UCMR 2 drinking water samples. However, EPA will require
systems to use UCMR 2-approved laboratories when conducting monitoring
for those analytes listed in Table 1 of Sec. 141.40(a)(3) of this
rule. A list of laboratories approved for UCMR 2 will be posted to
EPA's UCMR Web site: http://www.epa.gov/safewater/ucmr/ucmr2/labs.html.
Laboratories are encouraged to apply for UCMR 2 approvals as early as
possible, as schedules for large PWS sampling will be completed soon
after the final rule is promulgated. The steps for the laboratory
approval process are as follows:
a. Request to Participate. The laboratory must contact EPA
requesting to participate in the UCMR 2 laboratory approval process.
Laboratories must send this request to: UCMR 2 Laboratory Approval
Coordinator, USEPA, Technical Support Center, 26 West Martin Luther
King Drive (MS 140), Cincinnati, OH 45268; or e-mail at:
UCMR_Sampling_Coordinator@epa.gov. EPA will begin accepting requests for
registration forms for the methods associated with the UCMR Contaminant
List (including List 1, Assessment Monitoring, and List 2, Screening
Survey) beginning August 22, 2005. The laboratory must request the
necessary registration forms within 90 days after final rule publication.
b. Registration. EPA will send each laboratory that requests
registration forms to conduct UCMR 2 analysis a list of information
that EPA will need to process that application. This registration
information will provide EPA with the basic information about the
candidate laboratory: Laboratory name; mailing address; shipping
address; contact name; phone number; fax number; e-mail address; and
UCMR 2 methods for which the laboratory is seeking approval. Thus, the
purpose of the registration step is to ensure that EPA has all of the
necessary contact information, and that each laboratory receives a
customized application package that will include materials and
instructions for the methods that it plans to use.
c. Application Package. When EPA receives the registration
information, an application package will be sent to the laboratory for
completion. This application package will be customized to address only
those EPA methods selected in the laboratory's registration
information. EPA may provide analytical standards to be used when
conducting monitoring; however, laboratories will be required to
procure their own standards, where commercially available, to be used
to complete the application process. Information requested in the
application will include:
• IDC data, including precision, accuracy, and MRL studies;
• Information regarding analytical equipment;
• Proof of current drinking water laboratory certification;
and
• Example chromatograms for each method under review.
The laboratory must also confirm that it will post UCMR 2
monitoring results (on behalf of its PWS clients) to EPA's UCMR
electronic data reporting system.
d. EPA Review of Application Package. EPA will review the
application package and, if necessary, request follow-up information.
Satisfactory completion of this portion of the process will allow the
laboratory to participate in the UCMR 2 PT program.
e. Proficiency Testing. A PT sample is a synthetic sample
containing a concentration of an analyte that is known to EPA, but
unknown to the laboratory being tested. To complete the initial
laboratory approval process, a laboratory must successfully analyze
UCMR 2 PT sample(s) for each method for which the laboratory is seeking
approval. EPA intends to offer up to four opportunities for a
laboratory to successfully analyze the UCMR 2 PT samples. Up to three
of these studies will be conducted prior to the publication of the
final rule, but at least one study will be conducted after publication
of the final rule. When a laboratory passes a PT for one of the UCMR 2
methods, EPA will not send a PT sample for that method in later PT
opportunities. Laboratories applying for UCMR 2 approval, and
laboratories conducting UCMR 2 analyses, may be subject to on-site
laboratory audits. No PT studies will be conducted after the start of
monitoring. No laboratories will be approved that did not successfully
complete a PT study.
f. Written EPA Approval. After the first five steps (a. through e.)
have been successfully completed, EPA will send the laboratory a letter
listing the methods for which approval is pending (if the PT study and
laboratory evaluation is conducted prior to promulgation of the final
rule) or approval is granted (after promulgation of the final rule).
Laboratories receiving a pending approval may be automatically approved
following promulgation of the final rule, or they may need to repeat
all or part of the approval process, contingent upon what changes are
applied to the rule between proposal of the draft rule and promulgation
of the final rule. These letters will also include a reminder that the
laboratory may be subject to on-site audits.
2. Quality Control Requirements
For UCMR 2, EPA has made several changes to the quality control
requirements, which were previously located in Sec. 141.40, Appendix
A. The quality control steps in Appendix A information will be moved to
Sec. 141.40(a)(5). Requirements related to MRLs and to laboratory
approvals will be incorporated into this section of the proposed rule,
and are discussed in sections III.D and III.E.1, respectively. Changes
related to the quality control requirements include:
• The language regarding Detection Limits will be replaced
with the requirement to validate each laboratory's performance at or
below the MRL. Since UCMR 1 was promulgated, EPA has developed new MRL
and LCMRL procedures. The MRL procedures are now described in Sec.
141.40(a)(5). Guidelines and procedures for using LCMRLs in
establishing MRLs for UCMR 2 are described in this preamble, and in a
document entitled: ``Statistical Protocol for the Determination of the
Single-Laboratory Lowest Concentration Minimum Reporting Level (LCMRL)
and Validation of the Minimum Reporting Level (MRL)'' (USEPA, 2004j).
• The calibration step will be changed to remove the
requirement for acceptance ranges for each analytical method. Because
all of the methods approved for UCMR 2 monitoring specify calibration
acceptance criteria, it is not necessary to specify criteria in this rule.
• The requirement to analyze a field reagent blank (Reagent
Blank Analysis) will be removed because the analysis of a field reagent
blank is not required in any of the methods proposed for UCMR 2. None
of the analytes being proposed are sufficiently hydrophobic or volatile
enough for there to be a serious concern about sample contamination
during shipping.
• The requirement to analyze Quality Control Samples will be
removed since they are not available for the majority of the analytes
contained in this rule.
• The terms Matrix Spike and Matrix Spike Duplicate will be
replaced with Laboratory Fortified Sample Matrix and Laboratory
Fortified Sample Matrix Duplicate, respectively, to be consistent with
the terms specified in the data
[[Page 49110]]
elements table in Sec. 141.35(e) of today's proposed action.
• The language to describe Internal Standard Calibration
will be modified to more clearly describe the requirements.
• The requirements regarding the Method Performance Test
will not be changed.
• The requirements related to Detection Confirmation will be
revised to be consistent with the methods being approved in this rule.
Analytical results for perchlorate determined to be at or above the MRL
using Methods 314.0 and 314.1 are required to be confirmed by a second
chromatographic column, or by confirmation using Method 331.0 or 332.0,
before being reported. Alternatively, the primary analysis of
perchlorate may be conducted using either Method 331.0 or 332.0.
• Reporting requirements will be clarified and modified such
that laboratories will be required to report their data to EPA's
electronic data reporting system (http://www.epa.gov/safewater/
ucmr/ucmr2/reporting.html) within 120 days of sample collection. PWSs
have 60 days from the laboratory posting to review, approve, and submit the
data to the State and EPA via the electronic reporting system. After 60
days from the laboratory's posting, if the PWS has not approved and
submitted the data, the data will be considered approved and final for
EPA review.
No changes will be made to the requirements related to Sample
Collection and Preservation other than the addition of the requirement
for laboratories using Method 314.0 for the analysis of perchlorate to
preserve their samples as required in the other approved perchlorate
analysis methods. In addition, the requirements concerning Method
Defined Quality Control will not be changed.
F. How Are Systems Selected for UCMR Monitoring?
1. How Are Systems Selected for Assessment Monitoring?
a. Original Assessment Monitoring Statistical Approach for UCMR 1.
Under UCMR 1, Assessment Monitoring was specified to be conducted by
all large CWSs and NTNCWSs serving more than 10,000 people (e.g., a
census of large systems, totaling approximately 3,100), and by a
statistically representative sample of 800 small systems (systems
serving 10,000 or fewer people). The large size of the stratified
random sample allowed for a high level of confidence in the resulting
monitoring data and low error or uncertainty within the sample. The
List 1 contaminants monitored under Assessment Monitoring are the
priority contaminants for which analytical methods have already been
developed.
EPA identified DQOs for the representative sample of small systems
to include the following: data must provide unbiased national exposure
estimates; and margins of error must be kept to ±1 percent
with 99 percent confidence for CWSs and ±2.5 percent with 95
percent confidence for NTNCWSs. Use of a standard statistical design
formula to estimate the minimum sample size and an assumed estimated
occurrence of approximately 1 percent resulted in a minimum sample size
of 659 systems. The sample size was then adjusted upwards to account
for additional DQOs. Furthermore, the sample was stratified across
system size, water source, and type to account for differences in
vulnerability, differential occurrence, and management capacity, as
outlined below.
The small system representative sample was designed to account for
different system sizes, types of systems, sources of water supply,
contaminants likely to be found, and geographic location (e.g.,
States), as outlined in SDWA section 1445(a)(2)(A). The sample was
stratified considering the proportion of the population served by CWSs
and NTNCWSs by water source type (i.e., ground or surface water) and
system size category (i.e., serves 25 to 500 people, 501 to 3,300
people, and 3,301 to 10,000 people) within the water source type. This
stratification allowed EPA to account for different exposure risks of
contaminant occurrence that may be related to the differential
vulnerability of water sources and differing management and financial
capacity that can vary across system types and sizes.
EPA also allocated the selection of small systems across all the
States and territories to account for differences in spatial
vulnerability and contaminant occurrence and made adjustments to ensure
equity in participation. Because contaminant exposure assessment was a
primary goal of UCMR 1, EPA began with a base design that allocated
systems to States in proportion to the population served. This
population-weighted allocation leads to the best estimates of national
exposure. However, this approach, when strictly applied, assigns small
numbers of systems, or even zero systems, to the smallest States and
territories. To ensure the sample was fully representative of the
nation and to provide equity across States for involvement in the UCMR,
EPA adjusted the population-based design to include at least two
systems from each State and territory in the United States (with the
exception of Guam, which had only one PWS that qualified). Small Tribal
water systems in each of the 10 EPA Regions were grouped into a single
category for the representative sample. Thus, the Tribal category was
equivalent to a ``State'' for the statistical selection process, which
ensured that Tribal systems would be selected. Exhibit 7 summarizes the
system allocation across system sizes and water sources, including the
adjustment for a minimum of two systems per State.
Exhibit 7.--Approximate Sample Allocation for Assessment Monitoring: Expected Number of Systems Selected by
System Size and Water Source \1\
----------------------------------------------------------------------------------------------------------------
Surface water
Size category Ground water (and GWUDI) Total
systems systems \2\
----------------------------------------------------------------------------------------------------------------
500 and Under................................................... 103 57 160
501 to 3,300.................................................... 250 50 300
3,301 to 10,000................................................. 230 110 340
-----------------
Total................................................... 583 217 800
----------------------------------------------------------------------------------------------------------------
\1\ For more information see ``Statistical Design and Sample Selection for UCMR 1'' (USEPA, 2001c).
\2\ GWUDI = ground water under the influence of surface water.
[[Page 49111]]
To provide an improved understanding of contaminants and conditions
affecting small systems in UCMR 1, EPA selected 30 small PWSs from the
systems in State Monitoring Plans as ``Index Systems'' at which
contaminants would be monitored every year during the five-year cycle.
EPA conducted the sampling and testing for the Index Systems. At the
time of sampling, EPA also gathered other data to characterize the
environmental setting affecting the system including precipitation,
land and water resource use, and environmental data (such as soil type
and geology).
The details of the design are included in ``Statistical Design and
Sample Selection for the UCMR 1'' (USEPA, 2001c). The design of UCMR 1
was subjected to peer review and improved by recommendations of the
peer reviewers, as well as from suggestions made during the public
comment and response process in developing UCMR 1.
b. Proposed Assessment Monitoring Statistical Approach for UCMR 2.
EPA proposes to maintain the same basic statistical design for its UCMR
2 national representative sample of 800 small systems and to continue
with a census of large water systems for Assessment Monitoring. EPA
believes that the combination of a nationally representative sample of
small systems and a census of large systems provides a powerful tool
for assessing contaminant occurrence in PWSs, and believes that this is
the most effective and accurate survey approach, as long as methods,
laboratory capacity, and