EPA 815-2^6-003
 Friday,

 April 21, 2000
Part IV



Environmental

Protection Agency

40 CFR Parts 141 and 142
National Primary Drinking Water
Regulations; Radionuclides; Notice of Data
Availability; Proposed Rule

-------
21576
Federal Register/Vol.  65,  No. 78/Friday, April 21, 2000/Proposed Rules
ENVIRONMENTAL PROTECTION
AGENCY

40 CFR Parts 141 and 142
[FRL-6580-8]
RIN-2040-AC98

National Primary Drinking Water
Regulations; Radionuclides; Notice of
Data Availability

AGENCY: Environmental Protection
Agency.
ACTION: Notice of data availability for
proposed rules \vith request for
comments.	

SUMMARY: The Environmental Protection
Agency (EPA) proposed regulations to
limit the amount of radionuclides found
in drinking water on July 18,1991. In
general, the proposal revised current
National Primary Drinking Water
regulations (NPDWR); a NPDWR was
proposed for uranium which is
unregulated. Since that time, new
information has become available which
the Agency is considering in finalizing
these proposed regulations. In addition,
the 1996 Amendments to the Safe
Drinking Water Act (SDWA) contained
provisions which directly affect the
1991 proposed rule.
  This document presents additional
information relevant to the Maximum
Contaminant Level Goals (MCLGs), the
Maximum Contaminant Levels (MCLs),
and monitoring requirements contained
in the  1991 proposal. EPA is seeking
public review and comment on these
new data. The Agency is also soliciting
comments on several implementation
options that are being evaluated for
inclusion in the final regulations.
DATES: Written comments should be
postmarked or delivered by hand by
June 20, 2000.
ADDRESSES: Send written comments to
the W-00-12 Radionuclides Rule
Comment Clerk, Water Docket (MC-
4101), 1200 Pennsylvania Ave., NW,
Washington, DC 20460 or by sending
electronic mail (e-mail) to ow-
docket@epa.gov. Hand deliveries should
be delivered to: EPA's Drinking Water
Docket at 401 M Street, SW, East
Basement {Room EB 57), Washington,
DC 20460. Please submit an original and
three copies of your comments and
enclosures (including references). If you
wish to hand-deliver your comments,
please call (202) 260-3027 between 9:00
a.m. and 4:00 p.m., Monday through
Friday, excluding Federal holidays, to
obtain the room number for the Docket.
Please see Supplementary Information
under the heading "Additional
Information for Commenters" for
                    detailed filing instructions, including
                    electronic submissions.
                      The record for the proposal has been
                    established under the docket name:
                    National Primary Drinking Water
                    Regulations for Radionuclides (W-00-
                    12). The record includes supporting
                    documentation as well as printed, paper
                    versions of electronic comments. The
                    record is available for inspection from 9
                    a.m. to 4 p.m., Monday through Friday,
                    excluding Federal holidays at the Water
                    Docket, 401 M Street SW, East Basement
                    (Room EB 57), Washington, DC 20460.
                    For access to the Docket materials,
                    please call (202) 260-3027 to schedule
                    an appointment.
                    FOR FURTHER INFORMATION CONTACT: For
                    technical inquiries, contact David
                    Huber, Standards and Risk Management
                    Division, Office of Ground Water and
                    Drinking Water, EPA (MC-4607), 401 M
                    Street SW, Washington, DC 20460;
                    telephone (202) 260-9566. In addition,
                    the Safe Drinking Water Hotline is open
                    Monday through Friday, excluding
                    Federal holidays, from 9:00 a.m. to 5:30
                    p.m. Eastern Standard Time. The Safe
                    Drinking Water Hotline, toll free 1-800-
                    426-4791.
                    SUPPLEMENTARY INFORMATION:

                    Regulated Entities
                      Entities potentially regulated by the
                    Radionuclides Rule are public water
                    systems that are classified as either
                    community water systems (CWSs) or
                    non-transient non-community water
                    systems (NTNCWSs). Regulated
                    categories and entities include:
Category

State, Tribal, and
Local Govern-
ments.
Examples of regulated
entities
Privately-owned CWSs
and NTNCWSs.
Publicly-owned CWSs
and NTNCWSs.
                      This table lists the types of entities,
                     currently known to EPA, that could
                     potentially be regulated by the
                     Radionuclides Rule. It is not intended to
                     he exhaustive, but rather provides a
                     guide for readers regarding entities
                     likely to be regulated by the
                     Radionuclides Rule. Other types of
                     entities not listed in the table could also
                     be regulated. To determine whether
                     your facility is regulated by the
                     Radionuclides Rule, you should
                     carefully examine the applicability
                     criteria in §§ 141.15 and 141.26 of title
                     40 of the Code of Federal Regulations,
                     and the definitions of Community Water
                     systems and Non-Transient, Non-
                     Community water systems in § 141.2 If
                     you have questions regarding the
applicability of the Radionuclides Rule
to a particular entity, consult the person
listed in the preceding FOR FURTHER
INFORMATION  CONTACT section.

Additional Information for Commenters

  To ensure  that EPA can read,
understand and therefore properly
respond to your comments, the Agency
requests that commenters follow the
following format: type or print
comments in ink, and cite, where
possible, the paragraph(s) in this
document to which each comment
refers. Please use a separate paragraph
for each issue discussed and limit your
comments to the issues addressed in
today's Document.
  If you want EPA to acknowledge
receipt of your comments, enclose a
self-addressed, stamped envelope. No
facsimiles (faxes) will be accepted.
Comments also may be submitted
electronically to ow-
docket@epamail.epa.gov. Electronic
comments must be submitted as a
WordPerfect 8.0 or ASCII file avoiding
the use of special characters and forms
of encryption and must be transmitted
by midnight June 20, 2000. Electronic
comments must be identified by the
docket name, number, or title of the
Federal Register. Comments and data
also will be accepted on disks in
WordPerfect 8.0 or in ASCII file format.
Electronic comments on this document
may be filed online at many Federal
Depository Libraries.

Abbreviations and Acronyms Used in
This Notice

Organizations
APHA—American Public Health Association
ASTM—American Society for Testing and
  Materials
AWWA—American Water Works Association
ICRP—International Commission on
  Radiological Protection
NBS—National Bureau of Standards
NSF—National Sanitation Foundation
ANPRM—Advanced Notices of Proposed
  Rulemaking
ATSDR—Agency for Toxic Substances and
  Disease Registry
BNL—Brookhaven National Laboratory
CFR—Code of Federal Regulations
EML—Environmental Measurements
  Laboratory
ERAMS—Environmental Radiation Ambient
  Monitoring System
ERD—Environmental Radiation Data
ERIC—Educational Resources Information
  Center
FGR-13—Federal Guidance Report 13
FR—Federal Register
FRC—Federal Radiation Council
NAS-^National Academy of Sciences
NCHS—National Center for Health Statistics
NESHAP—National Emissions Standards for
  Hazardous Air Pollutants
NIRS—National Inorganic and Radionuclide
  Survey

-------
                     Federal  Register/Vol. 65,  No.  78/Friday, April  21, 2000/Proposed Rules
                                                                                 21577

 NIST—National Institute of Standards and
   Technology
 NODA—Notice of Data Availability
 NPDES—National Pollutant Discharge
   Elimination System
 NPDWRs—National Primary Drinking Water
   Regulations
 NRG—National Research Council
 NRC—Nuclear Regulatory Commission
 NTIS—National Technical Information
   Service
 ORNL—Oak Ridge National Laboratory
 SAB—Science Advisory Board
 RADRISK—a computer code for radiation
   risk estimation
 SWTR—Surface Water Treatment Rule
 T&C—Technologies and Cost document
 UCMR—Unregulated Contaminant
   Monitoring Rule
 USDOE—United States Department of Energy
 USDW—underground source of drinking
   water
 USEPA—United States Environmental
   Protection Agency                   i
 USGS—United States Geological Survey
 USSCEAR—United Nations Scientific
   Committee on the Effects of Atomic
   Radiation

 Units of Measurement
 Bq—Becquerel
 Ci—Curie
 EDE/yr—effective dose equivalent per year
 kBq—kiloBecquerels
 kBq/m 3—kiloBecquerels per cubic meter
 kg—kilogram
 kgpd—kilogram per day
 Mgkd—milligram per kilogram per day
 L—liter
 L/day—liter per day
 mg—milligram
 mg/L—milligram per liter
 mg/kg—milligram per kilogram
 mg UN/L—milligram uranyl nitrate per lit
 mg/kg/day—milligram per kilogram per d<
 mg U/kg/day—milligram uranium per
   kilogram per day
 mgd—million gallons per day
 mL—milliliter
 mrem—millirem
 mrem/yr—millirem per year
 Sv—Sievert
 uCi—microCurie
 uCi/kg—microCurie per kilogram
 ug or ug—microgram
 ug/g or ug/g—microgram per gram
 ug/L or ug/L—microgram per liter
 ug uranium/L—microgram uranium per liter
 fig uranium/kg/day—microgram uranium per
  kilogram per day
 uR/hr—micro Roentgen per hour
 uSv/cm—micro Sievert per centimeter
 NTU—Nephelometric Turbidity Unit
 pCi—picoCurie
 pCi/day—picoCurie per day
 pCi/g—picoCurie per gram
 pCi/L—picoCurie per liter
pCi/ug—picoCurie per microgram
 liter
rday
Other Terms
ACA—anticentromere antigen
ALP—alkaline phosphatase
AS—alpha spectrometry
BAT—best available treatment
 BEIR—biological effects of ionizing radiation
 BMG—p2-microglobulin
 CWS—community water systems
 DL—detection limit
 EDE—effective dose equivalent
 FSH—follicle stimulating hormone
 GGT—gamma glutamyl transferase
 GI—gastrointestinal
 IE—ion exchange
 LDH—lactate dehydrogenase
 LET—low energy transfer
 LOAEL—lowest observed adverse effect level
 LP—Laser phosphorimetry
 MCL—maximum contaminant levels
 MCLG—maximum contaminant level goals
 MDL—method detection limit
 n—number
 NAG—N-acetyl-p-D-glucosaminidas
 NTNC—non-transient, non-community
 NTNCWS—non-transient, non-community
   water systems
 PBMS—performance based measurement
   system
 PE—performance evaluation
 POE—point-of-entry
 POU—point-of-use
 PQL—practical quantitation level
 PT—performance testing
 PWS—public water systems
 RF—risk coefficient
 RfD—reference dose
 RO—reverse osmosis
 RSC—relative source contribution
 SM—standard methods
 SMF—standardized monitoring framework
 SPAARC—Spreadsheet Program to Ascertain
   Residual Radionuclide Concentration
 SSCTL—"Small Systems Compliance
   Technology List"
 Stnd. Dev.—standard deviation
 TR—target risk level
 UIC—underground injection control

 Table of Contents

 I. Purpose and Organization of this Document
 II. Statutory Authority and Regulatory
    Background
   A. Safe Drinking Water Act of 1974 and
    Amendments of 1986 and 1996
   B. The 1991 Proposal
   C. Court Agreement
   D. Statutory Requirements for Revisions to
    Regulations
 III. Overview of Today's Document
   A. Health Risk Consistency With Chemical
    Carcinogens
   B. Drinking Water Consumption
  C. Risk Modeling and the MCL
  D. Sensitive Sub-Population: Children
  E. MCL for Beta Particle and Photon
    Radioactivity
  F. Combined Ra-226 and Ra-228
  G. Gross Alpha MCL
  H. Uranium
  I. Inclusion of Non-Transient Non-
    Community Water Systems
  J. Analytical Methods
  K. Monitoring
  L. Effective Dates  .
  M. Costs and Benefits
IV. References

Appendices
I. Occurence
  II. Health Effects
  III. Analytical Methods
  IV. Treatment Technologies and Costs
  V. Economics and Impacts Analysis

  I. Purpose and Organization of This
  Document

   In 1976, EPA promulgated drinking
  water regulations for several
  radionuclides. In 1991 (56 FR 33050,
  July 18, 1991), EPA proposed revisions
  to the current radionuclides (i.e. beta
  and photon emitters, radium-226 and
  radium-228, and gross alpha radiation)
.  and proposed regulations for uranium
  which is not currently regulated. EPA is
  publishing this Notice of Data
  Availability (NODA) to inform the
  public and the regulated community of
  new information concerning
  radionuclides in drinking water. EPA is
  evaluating these additional data to
  determine how they will affect the
  Agency's decisions relative to final
  regulations to control radionuclides in
  public water systems. The Agency is
  under a court agreement to publish
  these final regulations by November
  2000. Information in today's Document
  includes data about the occurrence,
  health effects, and treatment options for
  radionuclides in drinking water, as well
  as analytical methods, and monitoring
  requirements. This Document also
  presents data concerning the costs and
  benefits of several regulatory options.
  EPA is soliciting public comment on a
  number of issues raised by this new
  information. This introduction provides
 an overview of the document, and some
  of the information available to EPA and
 to highlight the risk management
  decisions the Agency is contemplating.
 Subsequent sections will contain more
 specific information, with a focus on
 what is new, relative to each of the
 topics listed previously. Finally, to
 further assist the public, the Agency has
 compiled seven appendices, included
 with this NODA, with more detailed
 information on each of these topics in
 addition to the public docket of
 reference materials. EPA seeks comment
 on the data and information presented
 in today's NODA, particularly where
 regulatory options or alternatives are
 discussed. Commenters are asked to
 provide their rationale and any
 supporting data or information they
 wish to submit in support of comments
 offered.
   Table 1-1 summarizes the major
 elements of the 1976 rule, the 1991
 proposal and the issues being
 considered in today's NODA.

-------
21578
   Federal Register/Vol.  65, No.  78/Friday,  April 21, 2000/Proposed Rules
                   TABLE 1-1.—COMPARISON OF THE 1976 RULE, 1991 PROPOSAL, AND 2000 NODA
    Provision
                        1976 Rule (Current Rule)
                                               1991 Proposal
                                                                                                  2000 NODA
Affected Systems
                  CWS
MCLG	
Radium MCL
Beta/Photon
  Emitters MCL
Gross alpha MCL
 no MCLG	
 Combined Ra-226 + Ra-228 MCL of 5
   pCi/L.

 4 mrem: Methodology for deriving indi-
   vidual  concentration  limits   incor-
   porated by reference; MCL = sum of
   the fractions of dose from  one or
   more contaminants; risks estimated
j   not to exceed 5.6x10~5.
| 15 pCi/L excluding U and  Rn, but in-
I   eluding Ra-226.
Potonium-210 ,.	| Included in gross alpha
Lead-210
Uranium MCL	-

Ra-224	_	

Radium monitoring

Monitoring base-
  line.
Beta monitoring ....
Gross alpha moni-
  toring.

Analytical Methods
                  Not Regulated
 Not Regulated
 Part of gross alpha, but sample holding
   time too long to capture Ra-224.
 Ra-226 linked to Ra-228; measure Ra-
   228 if Ra-226>3 pCi/L and sum.
 4 quarterly  measurements.  Monitoring
   reduction  based on results: >50% of
   MCL required 4 samples every 4 yrs;
   <50%  of MCL  required  1  sample
   every 4 yrs.
 Surface water systems >100,000 popu-
   lation Screen at 50 pCi/L/; vulnerable
   systems screen at 15 pCi/L.
 Analyze up to one year later .


 Provide methods 	
                                                     CWS + NTNC
MCLG of zero	
Ra-226 MCL of 20 pCi/L; Ra-228 MCL
  of 20 pCi/L.

4 mrem ede  (Effective Dose  Equiva-
  lent).  Derived  concentration  limits
  changed to reflect new  dose limit;
  Current estimate of associated risks
  for these concentration limits are be-
  tween 10~4 and 10"3 for most.
"Adjusted" gross alpha MCL of 15 pCi/
  L, excluding Ra-226, radon, and ura-
  nium.
Included in gross alpha	'.	
Included in beta particle and photon ra-
  dioactivity; concentration limit  pro-
  posed at 1 pCi/L.

20 u,g/L or 30 pCi/L w/ option for 5-80
Part of gross alpha, but sample holding
  time too long to capture Ra-224.
Measure Ra-226 and -228 separately.

Annual samples for 3 years; Std Moni-
  toring Framework: >50%  of MCL re-
  quired  1   sample  every 3  years;
  <50%  of  MCL enabled  system  to
  apply for waiver to 1 sample every 9
  years.
Ground  and surface  water  systems
  within  15 miles of source screen at
  30 or 50 pCi/L. Those drawing water
  from a contaminated source screen
  at 15 pCi/L.
Six month holding time for gross alpha
  samples;  Annual  compositing  of
  samples allowed.
Method  updates proposed  in  1991;
  Current  methods  were updated in
  1997.
CWS  + several  NTNC options based
  on the 1991 proposal.
MCLG of zero.
Maintain current MCL based  on  cor-
  rected estimates  of risk of current
  MCL.
Maintain current MCL based  on  cor-
  rected estimates  of risk of current
  MCL.
-Maintain current MCL based on unac-
  ceptable risk level of 1991 proposed
  MCL.
No changes to current rule. Monitoring
  required under the, UCMR rule. Fu-
	jure_actipn" may be" proposed at a
 Jafer Hate.  	        "      _""	
No changes to current rule. Monitoring
  required under the UCMR rule. Fu-
  ture action  may be proposed at a
  later date
Three options  being  considered: 20,
  40, 80 u,g/L and pCi/L
Same as current rule, but Ra-224 may
  be addressed in a future proposal.
Measure Ra-226 and  -228 separately
Implement Std  Monitoring  Framework
  as proposed in 1991. Four initial con-
  secutive quarterly  samples in  first
  cycle. If initial average level >50% of
  MCL: 1 sample every 3 years; <50%
  of MCL: 1 sample every  6 years;
  Non-detect: 1 sample every 9 years.
  (beta  particle  and photon radioac-
  tivity has a  unique  schedule—see
  Section 111, part K).
Same as 1991  proposal with clarifica-
  tions.
As proposed in 1991. Recommendation
  to  analyze within  48-72 hours to
  capture Ra-224.
Current methods with clarifications.
n. Statutory Authority and Regulatory
Background
A. Safe Drinking Water Act of 1974 and
Amendments of 1986 and 1996
  Regulations for radionuclides in
drinking water were first promulgated
in 1976 as interim regulations under the
authority of the Safe Drinking Water Act
(SDWA) of 1974. The standards were set
for three groups of radionuclides: beta
and photon emitters, radium (radium-
226 and radium-228), and gross alpha
radiation. These standards became
effective in 1977.
  The SDWA Amendments of 1986
required EPA to establish health-based
                        regulatory targets, called Maximum
                        Contaminant Level Goals (MCLGs), for
                        every contaminant "at the level at
                        which no known or anticipated adverse
                        effects on the health of persons occur
                        and which allows an adequate margin of
                        safety." The enforceable standard, the
                        Maximum Contaminant Level (MCL),
                        was required'to be established "as close
                        to the health-based goal as feasible using
                        the best available technology, taking
                        costs into consideration." EPA proposed
                        an MCLG of zero for the radionuclides
                        in 1991.
                          to 1983 and 1986, EPA published an
                        Advanced Notice of Proposed
                        Rulemaking (ANPRM) requesting
                             additional information and comments
                             on radionuclides and numerous'organic
                             and inorganic contaminants in drinking
                             water. The 1986 SDWA Amendments
                             identified 83  contaminants for EPA to
                             regulate, including the currently
                             regulated radionuclides, which lacked
                             an MCLG, and two additional
                             radionuclides, uranium and radon. The
                             Amendments also declared the 1976
                             interim standards to be final National
                             Primary Drinking Water Regulations.
                               In 1996, Congress again amended the
                             SDWA. These amendments included
                             new and revised provisions that must be
                             considered when revising drinking
                             water regulations. Among these are the

-------
                   Federal Register/Vol.  65, No. 78/Friday, April 21, 2000/Proposed Rules
                                                                      21579
 health protection clause (section
 1412 (b) (9)) which requires that "any
 revision of a national primary drinking
 water regulation (NPDWR) shall be
 promulgated in accordance with this
 section, except that each revision shall
 maintain, or provide for greater
 protection of the health of persons."
   The 1996 Amendments also provide
 for a cost-benefit analysis when
 publishing a proposal for new NPDWRs
 pursuant to section 1412 (b)(6). While
 the EPA had proposed the radionuclides
 rule prior to these Amendments, the
 Agency nevertheless conducted an
 analysis of the costs and associated
 benefits of all of the options described
 in today's Document. These analyses
 serve to update and revise the costs and
 benefits estimated for the 1991 proposed
 rule. For the uranium standard, the
 Agency solicits comment on the
 possible use of its new discretionary
 authority at section 1412(b)(6) of the
 SDWA, which allow for a proposed
 regulatory level to be set higher than the
 feasible level, after the Agency has made
 a determination that the benefits do not
 justify the costs at the feasible level.
 Note that section 1412(b)(6) applies to
 new standards (uranium), not to the
 revision of existing standards (combined
 radium-226  and -228, gross alpha, and
 beta particle and photon radioactivity).
 Where we expect to maintain current
 standards at their existing levels, no
 additional analysis was undertaken
 because the rule is already in effect.
 B. The 1991  Proposal
  In 1991, EPA proposed new
 regulations for uranium and radon, as
 well as revisions to the existing
 regulations.  The proposal included the
 following features: (1) an MCLG of zero
 for all ionizing radiation; (2) revised
 MCLs for beta particle and photon
 radioactivity, radium-226, radium-228,
 and gross alpha emitters; (3) proposed
 MCLs for uranium and radon; and (4)
 revisions to the categories of systems
 required to monitor, the monitoring
 frequencies,  and the appropriate
 screening levels. EPA received
 comments on the new data and
 regulatory options presented in the 1991
 proposal. However, the proposal was
 never promulgated as a final rale in
 large part because of controversy
 surrounding the proposed MCL for
radon. The 1996 Amendments to the
SDWA directed the Agency to withdraw
the proposed MCL for radon, which was
subsequently done on August 6,1997
 (62 FR 42221).
  Most of the comments EPA received
on the proposal related to radon.
Approximately 120 comments related to
non-radon radionuclides were valuable
 and most are still germane to the
 Agency's rulemaking efforts. Those
 comments are addressed, as appropriate,
 in today's document.
 C. Court Agreement
   The SDWA (as amended in 1986)
 provided a statutory deadline to
 promulgate a revised radionuclide rule
 of June 1989, but EPA failed to meet this
 deadline. An Oregon plaintiff brought
 suit to require EPA to issue the
 regulations and EPA entered into a
 series of consent agreements setting
 schedules to issue regulations for the
 radionuclides. EPA issued a proposal in
 1991. After the SDWA Amendments in
 1996, EPA agreed to publish a final
 action with respect to the proposed
 regulation for uranium by November 21,
 2000. EPA also agreed to either take
 final action by the same date with
 respect to radium, beta/photon emitters,
 and alpha emitters or publish a notice
 stating its reasons for not taking final
 action on the proposal. This latter
 scenario would leave the current rule in
 effect.

 D. Statutory Requirements for Revisions
 to Regulations
   Both the 1986 and the 1996
 Amendments to the SDWA state that
 revisions be made to existing drinking
 water regulations periodically. Section
 1412(b)(9) of the 1986 SDWA
 Amendments directed  that "national
 primary drinking water regulations be
 amended whenever changes in
 technology, treatment techniques, and
 other means permit greater protection of
 the health of persons, but in any event,
 such regulations shall be revised at least
 once every 3 years." The 1996 SDWA
 Amendments provide that EPA " * * *
 not less than every 6 years review and
 revise, as appropriate, each national
 primary drinking water regulation," and
 that "any revision shall maintain, or
 provide for greater, protection of the
 health of persons."
   The radionuclides emit ionizing
 radiation and, absent data indicating
 that there is a threshold level at which
 exposure does not present a risk, EPA
 uses a linear, non-threshold model to set
 a zero MCLG for radionuclides. This
 means that any exposure can potentially
 cause harm and that risk associated with
 the exposure increases  proportionally to
 the concentration of the radionculide.
  EPA's current estimate of the unit
 risks posed by many of the
 radionuclides covered by today's
 document has generally increased
relative to the 1991 estimate. In fact,
based on the newest science (Federal
 Guidance Report 13), the fatal cancer
risks associated with the 1991 proposed
 MCL changes for combined radium,
 gross alpha, and beta particle and
 photon radioactivity generally exceed
 the Agency's risk range of 10 ~6 to 10 ~4.
 This document discusses and requests
 comment on the issues EPA has
 addressed in determining how to best
 meet applicable SDWA provisions for
 each of the radionuclide  categories
 covered by today's document.

 IH. Overview of Today's Document
   Additional data since the 1991
 proposal suggest a need to retain some
 portions of the proposal,  while retaining
 much of the current rule. Any changes
 that are finalized must meet the
 provisions for public health protection
 in accordance with the 1996
 Amendments. EPA has presented its
 approach for finalizing the non-radon
 portions of the 1991 radionuclides
 proposal at several public meetings.
   In December 1997 EPA held a public
 forum (stakeholder meeting) to discuss
 the requirements and limitations of the
 new Amendments pertaining to
 revisions to the radionuclide regulation.
 The Agency discussed  most of the
 concepts presented in this document
 and received valuable feedback from the
 public,  the regulated community, and
 other Federal Agencies. In this
 Document, EPA is presenting the
 current information and options upon
 which the Agency will  make its
 decisions regarding revisions to the
 existing standards. At the same time, the
 Agency is requesting additional data
 and comments on the approach EPA
 expects to take in formulating the final
 rule.
   The most significant  new information
 concerns the occurrence, monitoring,
 and health effects of radionuclides in
 drinking water. Recent  data suggest a
 more widespread occurrence of certain
 radionuclides which may point to a
 need for improved monitoring for these
 radionuclides in certain areas of the
 country. Conversely, a better
 understanding of the occurrence
 patterns may also indicate the need for
 less frequent monitoring. The newest
 health effects models, which are based
 on improved age-dependent biokinetic
 and dosimetric models  of the effects of
 ionizing radiation on the body and more
 recent epidemiological information,
 reveal that radionuclides generally
 present a somewhat greater risk than the
 estimates of previous  models, including
 the 1991 RADRISK model. EPA's
 publication "Federal Guidance Report
 13" (FGR-13, EPA 1999b) discusses the
newest risk modeling. The resulting risk
estimates based on of the new health
effects models are largely the reason for
the publication of this document. The

-------
21580
Federal Register/Vol. 65, No.  78/Friday, April 21, 2000/Proposed Rules
following are some aspects of the NOD A
which the Agency would like to
highlight.
A. Health Risk Consistency With
Chemical Carcinogens
  The risks associated with exposure to
chemical carcinogens are usually
expressed as the risks of illness. It is
EPA policy to issue standards that
maintain a risk ceiling in the target risk
range of 10 ~6 (one in one million) up
to 10~4 (one in ten thousand). For
consistency between the level of
protection between chemical and
radiological drinking water
contaminants, EPA is considering
utilizing \vhichever risk provides the
greater protection for MCL changes, a
1x10" 4 risk of cancer incidence, or a
mortality risk at half the incidence,
5x10 ~ *. The risk of death at 5x10 - s is
the more protective if the mortality rate
from a particular radionuclide is more
than 50%, whichris true for most of the
radSonuclides. However, for the thyroid,
the mortality rate from thyroid cancer is
at 10%. Protecting at lxlO~4 incidence
corresponds to a mortality at lxlO~5.
Conversely, protecting at 5x10~5
mortality with only a 10% mortality rate
allows an incidence, of 5xlO~4, a less
protective number.'
B. Drinking Water Consumption
  EPA received comments in 1991 from
the American Water Works Association
(AWWA), the Colorado Water Quality
Commission, the Atlantic Richfield Co.,
and the Rio Algom Mining Corp.
suggesting that consumption of drinking
water was actually 1.2 liters per day,
thus EPA was being too conservative in
using two liters per day.
  When establishing an MCL for a
carcinogen, the risk which the MCL
would represent is considered as well as
treatability and costs. Radionuclides
will have an MCLG of zero, with MCLs
based on standard assumptions of two
liters intake per person per day (2 L/
day), an average individual weight of 70
kg, and a 70 year life span. EPA now has
data to indicate that the average
consumption of tap water is 1.1 liters
per day per person and that a
consumption rate of 2.2 L/day
represents the 90th percentile
consumption level.1 Basing the MCL on
a consumption rate higher than the
average value is justified since MCLs are
intended to be protective of the persons
that comprise the population and not
  11f orm ranked, from lowest to highest, the
average doily water consumption levels for every
CVVS customer in the U.S., the "90th percentile"
value of 2.2 L/day is the best estimate of the value
for which 90 percent of the population would drink
that much or less on an typical day.
                    just "typical individuals". Since a
                    consumption value of 2 L/day is less
                    than the 90th percentile consumption
                    rate, EPA believes that its assumption of
                    2 L/day for MCL determinations is not
                    overly conservative and is justifiable.
                      When computing the national benefits
                    of a regulation and the estimate of
                    cancer mortality risks or risk reductions,
                    EPA is now using 1.1 liters per person
                    per day (L/day) of water as the estimate
                    of the average daily consumption rate
                    for individuals. In effect, this reduces
                    population risk estimates by
                    approximately one half and reduces the
                    estimate of risk reductions by
                    approximately one half. Since benefits
                    calculations are based on risk
                    reductions, this reduces monetized
                    benefits by approximately one half. It
                    should be noted that it is consistent to
                    set health protection levels based on a
                    subset of individuals that face the
                    highest risks (sensitive subpopulations
                    and/or the substantial minority  of the
                    population have higher water
                    consumption levels), while estimating
                    benefits based on average individuals  ..
                    (average consumption and sensitivity).
                    EPA believes this approach leads to
                    protective MCLs and realistic benefits
                    calculations.
                    C. Risk Modeling and the MCL
                      The Agency's current radionuclides
                    health effects model is based on Federal
                    Guidance Report 13 (FGR-13, EPA
                    1999b). The Agency's new health effects
                    model uses state-of-the-art methods,
                    models and data that are based on the
                    most recent scientific knowledge.
                    Compared with the approaches used in
                    1976 and 1991, the revised methodology
                    includes substantial refinements
                    (described in appendix II, "Health
                    Effects"). While commenters have
                    pointed out the MCLs in the current rule
                    are based on "old science", the newest
                    science indicates that many of the MCLs
                    proposed in 1991 have corresponding
                    risks that are much greater than the
                    upper limit of the Agency's acceptable
                    lifetime excess risk range of
                    approximately 10 ~6 to 10 ~4 (one in one
                    million to one in ten thousand lifetime
                    excess risk of cancer). The risks
                    associated with each existing and
                    proposed MCL are described in  sections
                    that follow.  The risk models are
                    described in detail in appendix  II
                    (Health Effects) and in the Technical
                    Support Document for the
                    Radionuclides Notice of Data
                    Availability (EPA 2000a).
                      Between 1976 and the present,
                    different scientific models have been
                    used to calculate risks from radiation
                    exposure. Each model derives a
                    different concentration of a particular
nuclide for a given level of risk. For
example, in 1991, the RADRISK model
indicated that consuming drinking
water with radium-228 at 26 pCi/L
would lead to an excess lifetime cancer
risk of 1x10 ~4- However, using today's
model (based on Federal Guidance
Report 13), the best estimate of lifetime
risk of Ra-228 at 26 pCi/L is 1x10 ~3, a
risk value ten times greater than thought
in 1991.
  Likewise, the 1991 proposed MCL for
Ra-228 at 20 pCi/L was thought to
correspond to lifetime excess cancer risk
of 7.7xro~A The most current risk
estimate for Ra-228 at 20 pCi/L
7.7xlO~4, again ten-fold greater and
much higher than the Agency's target
risk ceiling of 10~4. For individuals
consuming water with 20 pCi/L of both
Ra-228 and Ra-226, the risk was thought
to be 1.7X10-4 in 1991. However, based
on the newest science, these individuals
would be exposed to lifetime excess
risks of lxlO~3 risk (one in a thousand),
a risk level 10-fold higher than the
Agency's target risk ceiling for drinking
water MCLs. EPA requests comments on
these issues.

D. Sensitive Sub-Population: Children

  The age-specific, sex-specific models
used by EPA for estimating risk from
ionizing radiation implicitly provide for
risk differentiation by gender and age.
The computer program suite, DCAL
(FGR—13), uses age-specific metabolic
models to calculate the dose from a unit
intake of a radioisotope during each
year of life from birth to 120 years of
age. Age-specific organ masses are used
for all ages up to adult, and for adult
males and adult females. Risk
coefficients are given by age and sex for
each year of life from birth to 120 years
of age. The risk is then calculated by
combining calculated doses and age-sex-
specific risk coefficients with age-sex-
specific intake data and age-sex-specific
survival data.
  A separate risk analysis for children
was performed and is described in
appendix II (Health Effects), part C.
Risks to children are explicitly
considered when setting MCLs for
radionuclides. In the case of the
regulated water systems (currently,
community water systems), children are
fully protected. In the case of the
unregulated systems of potential
concern (non-transient non-community
water systems, NTNCWSs), the analysis
is more complicated. Risks to children
served by NTNCWSs are discussed in
appendix II, part C, number 3.

-------
                   Federal Register/Vol. 65, No.  78/Friday, April 21,  2000/Proposed Rules
                                                                    21581
E. MCL for Beta Particle and Photon
Radioactivity

1. EPA's Plans for Finalizing the 1991
Proposed MCL for Beta and Photon
Radioactivity
  This section presents the important
considerations that have led EPA to
consider retaining the current MCL for
beta particle and photon radioactivity
when the 1991 proposal is finalized in
November of 2000. EPA is, however,
also considering finalizing the 1991
proposed changes to the monitoring
requirements for beta particle and
photon radioactivity, as described later
in this section. The current MCL is (40
CFR 141.16):
  (a) The average annual concentration
of beta particle and photon radioactivity
from man-made radionuclides in
drinking water shall not produce an
annual dose equivalent to the total body
or any internal organ greater than 4
millirem/year.
  (b) Except for the radionuclides listed
in Table A, the concentration of man-
made radionuclides causing 4 mrem
total body or organ dose equivalents
shall be calculated on the basis of a 2
liter per day drinking water intake using
the 168 hour data listed in "Maximum
Permissible Body Burdens and
Maximum Permissible Concentrations
of Radionuclides in Air or Water for
Occupational Exposure," NBS
Handbook 69 as amended August 1963,
U.S. Department of Commerce. If two or
more radionuclides are present, the sum
of their annual equivalent to the total
body or to any organ shall not exceed
4 millirem/year.

TABLE A.—AVERAGE  ANNUAL  CON-
  CENTRATIONS     ASSUMED      To
  PRODUCE A TOTAL BODY OR ORGAN
  DOSE OF 4 MREM/YEAR.
Radionuclide
Tritium
Strontium-90 ....
Critical organ
Total body
Bone marrow ..
pCi per
liter
20 000
8
  Following these instructions leads to
a unique list of concentration limits for
168 other man-made radionuclides. This
list is included in today's document in
appendix II, "Health Effects."
  The 1991 proposed MCL for beta
emitter and photon radioactivity was 4
mrem-ede (effective dose equivalents),
with the footnote:
  "NOTE. —The unit mrem-ede/yr refers to
the dose committed over a period of 50 years
to reference man (ICRP 1975) from an. annual
intake at the rate of 2 liters of drinking water
per day."
   Following these instructions leads to
 a unique list of concentration limits for
 230 radionuclides. EPA has determined
 that there is no way to update the 4
 mrem dose basis (1976) for the beta
 particle and photon radioactivity MCL
 without the extensive process of a new
 proposal. While some stakeholders have
 suggested that reverting to the existing
 rule for beta particle and photon
 radioactivity ("beta emitters") is relying
 on "old science," it should be pointed
 out the newest risk estimates, based on
 the peer-reviewed Federal Guidance
 Report 13,  indicates that the risks
 associated  with the 1991 proposed MCL
 of 4 mrem-ede (effective dose
• equivalents) are above the 10~4 risk
 level (10~3 to 10~4) for many of the beta
 emitters. Figure 1 shows the most
 current risk estimates for the beta
 emitter concentration limits derived
 under both the current and proposed
 MCLs. As the figure shows, the current
 MCL results in concentration limits
 with risks that fall within the Agency's
 risk range goal of 10~6 to 10~4 (while
 some are slightly above and some
 slightly below, all round to values
 within these orders of magnitude).
 BILLING CODE G56O-50-U

-------
21582
Federal Register/Vol. 65, No. 78/Friday, April 21, 2000/Proposed Rules
                  c
                  2
                  o

                  a.
                  m
                  O
                  •o
                  0)
                  CO
                  O
                  n.
                  o
                  c .>
                  co .»»
                  -w  O
                  c  «
                  o a:
                  10
                  JH
                  JO

                  o:

                  CO
                  (9
                  O

                  3
                  ai

                  o>
                  u.

                                                                         CD
                                                                         Q.

                                                                        T3

                                                                         to
                                                                         

                                                                        a:
                                         >|Siy JSOUBO IBJBJ 5330x3
BtLUNS CODE 6560-5O-C

-------
                   Federal Register/Vol. 65, No. 78/Friday,  April 21, 2000/Proposed Rules
                                                                    21583
   In summary, the Agency fully
 recognizes that the dose-based MCL of
 4 mrem/year is based on older scientific
 models. However, the Agency has
 decided to retain the current MCL given
 that:
   • Federal Guidance Report 13 (FGR-
 13, EPA 1999b) demonstrates that the
 1991 proposed MCL of 4 mrem-ede/year
 results in concentration limits that are
 outside the 10~6 to 10~4 range;
   • FGR-13 demonstrates that the
 current MCL of 4 mrem/year results in
 concentration  limits that are within the
 10~6to 10~4 range;
   • the fact that there is no  evidence of
 appreciable occurrence of man-made
 beta emitters in drinking water;
   • the 1996 Safe Drinking Water Act
 requires EPA to evaluate all NPDWRs
 every six years ["Six Year Review").
  EPA believes that Six Year Review is
 the appropriate vehicle for updating the
 beta particle and photon radioactivity
 MCL.

 2. Beta Particle and Photon
 Radioactivity Monitoring
  Currently, surface water systems
 serving more than 100,000 persons are
 required to monitor for beta particle and
 photon radioactivity using a screening
 level of 50 pCi/L, while systems that are
 determined to  be vulnerable by the State
 are required to monitor using a
 screening level of 15 pCi/L. In 1991,
 EPA proposed  that all ground water and
 surface water systems within 15 miles of
 a potential source, as determined by the
 State, be required to monitor using a
 screening level of 30 or 50 pCi/L. EPA
 is considering  retaining the current
 monitoring requirement of a 15 pCi/L
 screen for water systems drawing water
 from contaminated sources. EPA solicits
 comment on these issues. EPA is taking
 comment on screening levels of 30 or 50
pCi/L for systems within 15 miles of a
potential  source.
3. Lead-210 and Radium-228
  The 1991 proposal included lead-210
 (Pb-210) and radium-228 (Ra-228) in the
list of regulated beta and photon
emitters, both of which are naturally
 occurring. An 1991 the Agency was
 considering raising the Ra-228 MCL to
 20 pCi/L, which is high enough to
 significantly contribute to gross beta
 levels. However, since the Agency is
 retaining the current combined Ra-226
 and Ra-228 standard of 5 pCi/L, Ra-228
 will no longer be a significant
 contributor to gross beta. For the reason,
 the Agency sees no value in including
 Ra-228 in the list of beta/photon
 emitters.
   New risk analyses indicate that Pb-
 210 is of concern well below the current
 and proposed screening levels for beta
 and photon emitters. In order to assess
 the occurrence of Pb-210 to determine if
 it is present at levels high enough to
 warrant separate monitoring, EPA has
 included it on the list published in the
 Unregulated Contaminant Monitoring
 Rule (UCMR) (64 FR 50556, Friday,
 September 14, 1999). USGS also
 monitored for Pb-210 in its study with
 EPA of 100 locations. The reader is
"referred to appendix I and the Technical
 Support Document (EPA 2000a) for
 further information regarding this study.
 Since Pb-210 specific monitoring was
 not proposed in 1991, EPA cannot
 address this concern without a new
 proposal. After occurrence data has
 been reviewed from the UCMR, EPA
 may propose appropriate actions.

 F. Combined Ra-226 and Ra-228
 1. MCL Considerations
  The combined radium-226 and -228
 NPDWR has long been a contentious
 issue. A number of water systems
 believe  the current MCL is too stringent
 and have not installed treatment or
 taken other measures to comply. EPA
 first proposed the possibility of
 increasing the current 5 pCi/L limit for
 combined radium-226 and -228 in 1991.
 The proposal suggested a new level of
 20 pCi/L for Ra-226 and Ra-228
 separately along with a proposed limit
 of 300 pCi/L for radon-222 . This
 combination was proposed in part due
to the disproportionate costs of
removing radium compared to radon.
The proposal was met with opposition,
 largely due to the controversy
 surrounding the radon component. In
 the ensuing deliberations, debates
 regarding the radon component of the
 proposal interfered with promulgation
 of the proposal. In the 1996
 Amendments to the SDWA, Congress
 directed EPA to remove the-radon
 component from the proposal.
 Consequently, the Agency has once
 again considered the issues surrounding
 the allowable concentration of radium-
 226 plus radium-228 in drinking water.
   EPA is considering retaining the
 current MCL for combined radium-226
 and -228 at 5 pCi/L for the following
 reasons. First, the unit risks for Ra-226
 and Ra-228 are believed to be much
 greater than estimated in 1991, such that
 raising the combined Ra-226 and Ra-228
 MCL up to 20 pCi/L for each
 radionuclide would result in a lifetime
 excess cancer risks that are ten-fold
 higher than the Agency's acceptable risk
 range of 10 ~6 to 10 ~4. And second, EPA
 is required to consider the MCL for Ra-
 226 and Ra-228 apart from any NPDWR
 for radon, both by the 1996 SDWA
 Amendments and the later court
 stipulated agreement. Both points are
 discussed further here.
   First, in 1976 the estimate of risk from
 either Ra-226 or Ra-228 at 5 pCi/L was
 between 5x10 ~5 and 2 xlO  -4,
 averaging 1x10 ~4. In 1991 the RADRISK
 model calculated that a lxlO~4 risk
 corresponded to Ra-228 at 26 pCi/L and
 Ra-226 at 22 pCi/L.
   Table III-l shows the change in
 estimated risks from 1976 until the
 present. "Current Risk Estimates" are
 calculated using the 1999 model, FGR-
 13 (EPA 1999b). The table allows a
 comparison between the calculated risk
 during each phase of the evolution of
the radionuclides NPDWRs, including
the current best estimate of risk based
upon FGR-13 (EPA 1999b). Details of
why the models have changed and the
additional data taken into consideration
are found in the appendix II and the
Technical Support Document (EPA
2000a).
               TABLE 111-1 .—CHANGES IN ESTIMATED RISKS FOR VARIOUS RA-226 AND RA-228 LEVELS

Year model used
2000 FGR-13 	
2000 FGR-13 	 	 	
1994 FGR-11 	 	 	
1991 RADRISK 	 	 	 	
1991 RADRISK proposed MCL ....
1991 RADRISK 	 	 	

Concentra-
tion pCi/L
5
25
11
26
20
5
Radium-228
Previous risk
estimate
2 x 10~4
1 x 10~4
1 x 10~4
1 x 10~4
7 7 x 10~5
1.9 x 10-s

Current risk
estimate
2 x 10~4
1 x 10~4
4 5 x 10~4
1 x 10~~ 3
7 7 x 10~4
? -x 1D-4

Concentra-
tion pCi/L





z.
Radium-226
Previous risk
estimate





o ^ v -in-s

Current risk
estimate
.






-------
21584
Federal Register/Vol. 65, No.  78/Friday, April  21,  2000/Proposed Rules
         TABLE Hl-1.—CHANGES IN ESTIMATED RISKS FOR VARIOUS RA-226 AND RA-228 LEVELS—Continued

Year model used
1976* 	 	 	

Concentra-
tion pCi/L
5
Radium-228
Previous risk
estimate
1 x 10-"
i
Current risk
estimate
2x10-5

Concentra-
tion pCi/L
5
Radium-226
Previous risk
estimate
1x10-'

Current risk
estimate
7.3x10-i
  "The risk of either radium-226 or radium-228 at 5 pCi/L was believed to be between 5x10~5 and 2x10~4 in 1976. The average would have
been 1xiO~4,
  The 1991 estimated risk
corresponding to 20 pCi/1 of Ra-226 in
addition to 20 pCi/1 of Ra-228 was
thought to be 1.7 x 10~4. However, the
current risk estimate based on FGR—13
(EPA 1999b) for 20 pCi/1 of Ra-226 in
addition to 20 pCi/1 of Ra-228 is ixlQ-3
(one in a thousand), an order of
magnitude (ten times) above the
acceptable risk of 1x10 ~4.
  In contrast, maintaining the current
standard would allow a maximum
lifetime risk of 2x10 ~4 (within the
original risk range of the 1976
regulation). This represents a one in
5,000 lifetime mortality risk and would
only be present if 5 pCi/L in the
drinking water xvere all radium-228, a
relatively rare occurrence situation. If
the radium present were all radium-226,
the risk would be 7x10 ~ s, just below
EPA's risk ceiling. Since:
  • the risks associated with the current
MCL of 5 pCi/L are already at the upper
end of the Agency's allowable risk range
of 10 ~s; and
  • the 1991 proposed MCLs for Ra-226
and Ra-228 have risks as high as
IxlO-3, ten-fold higher than the
Agency's allowable risk, the Agency
believes that maintaining the current
MCL for combined Ra-226 and Ra-228 is
the appropriate action.
  Regarding treatment feasibility, EPA's
determination that water systems can
feasibility treat and quantify combined
radium at 5 pCi/L is supported  by case
studies of systems that had combined
radium levels in excess of the MCL and
that later came into compliance through
treatment. In addition, EPA has case
studies of systems that have come into
compliance through purchasing water,
blending, and developing new wells
(EPA 2000a).
  Since risk estimates for Ra-228 are
significantly higher than thought in
1991, EPA has evaluated the risk
reductions, costs, and benefits of
decreasing the allowable level of
radium-228 to 3 pCi/L and has
discussed the results in the Technical
Support Document (EPA 2000a). The
concern is that a system with 5  pCi/L of
Ra-228 with insignificant levels of Ra-
226 would be in compliance with the
combined radium MCL, but would have
                    an associated lifetime excess cancer
                    morbidity risk of 2 x 10 ~4, which
                    exceeds the risk ceiling on 1 x 10 ~4.
                    While this is true, the occurrence data
                    reported in appendix I suggest that this
                    situation should be rare. Since EPA did
                    not propose this action in the 1991
                    proposal, EPA cannot address this
                    concern in the finalization of this
                    proposal. However, EPA will consider
                    this situation further and will later
                    determine if a regulatory action is
                    appropriate.
                      An unintended effect in the 1991
                    proposal was that the costs and benefits
                    were not evenly distributed to all
                    affected persons (individuals). In the "
                    1991 proposal, an MCL was proposed
                    for radon at 300 pCi/L and a revised
                    MCL for radium from 5 pCi/L combined
                    for both radium-226 and radium-228 to
                    20 pCi/L each. Benefits and costs were
                    considered together for both radon and
                    radium on a national basis. Compared to
                    radium, radon is easier and cheaper to
                    remove from water due to its air
                    strippability. Since the risks avoided
                    were higher and the treatment costs
                    lower for the radon MCL, it was
                    reasoned that the radon rule was much
                    more cost-effective than the combined
                    radium rule. However, since radium and
                    radon do not tend to co-occur,
                    individuals that would have benefitted
                    from the radon rule were not the same
                    individuals that would have faced
                    higher risks under the proposed radium
                    MCLs. EPA believes that such a trade-
                    off is no longer appropriate. Among
                    other considerations, the 1996
                    Amendments to SDWA explicitly
                    separated the radon rule from the rule
                    for the other radionuclides.
                      In summary, EPA based its proposed
                    increase in the radium standard on the
                    risk models that existed  at that time and
                    on a population risk trade-off with
                    radon. The models in use in 1991
                    indicated that radium posed less of a
                    risk than originally believed in 1976.
                    However, current risk models (FGR—13,
                    EPA 1999b) suggest that the combined
                    radium standard of 5 pCi/L presents an
                    even greater health risk than thought in
                    1976. Given the  much higher current
                    estimate of risks associated with the
                    proposed Ra-226 and Ra-228 MCLs of 20
pCi/L and the statutorily required
withdrawal of radon-222 from the
proposal, the Agency believes that the
MCLs for radium proposed in 1991 are
no longer appropriate. EPA requests
public comment on retaining the current
radium standard of 5 pCi/L for
combined Ra-226 and Ra-228.

2. Separate Radium Analysis
  The 1991 proposal recommended
decoupling the monitoring of radium-
228 from radium-226. The current
radionuclides rule requires analysis of
Ra-228 only when Ra-226 levels are
above 3 pCi/L. The rule recommends
analysis of Ra-226 and/or Ra-228 when
gross alpha exceeds 2 pCi/L where Ra-
228 may be present, and requires
analysis of Ra-226 when gross alpha
exceeds 3pCi.L.
  Ra-228 may be present with minor
amounts of Ra-226 or in the absence of
Ra-226. In general, the mobility of a
parent raclionuclide may be very
different from that of a daughter
element, depending on the geochemistry
of the elements involved. However, the
occurrence of a radionuclide may still
be governed by the occurrence and
distribution of its parent (see EPA
2000a). Since radium-226 arises from
the uranium decay series and radium-
228 arises from the thorium series, it is
logical to expect them to occur
independently of one another. Also, the
parents of Ra-226 (uranium isotopes)
and Ra-228 (thorium isotopes) have very
different geochemical behaviors.
Uranium is fairly mobile in oxidizing
ground waters, while thorium is rather
insoluble. In contrast, the daughter
radium isotopes are more mobile in
reducing waters and are relatively
immobile in oxidizing waters. Since Ra-
226 is part of the uranium series
(relatively mobile parent) and Ra-228 is
part of the thorium series (immobile
parent), Ra-226 can and does mobilize
in waters containing Ra-228  more
frequently than the reverse situation.
These observations indicate that Ra-226
and Ra-228 may be expected to
significantly co-occur, but that the
correlation will not be strong enough  to
use the occurrence of one to  predict the
other with acceptable certainty. Recent

-------
                   Federal Register/Vol. 65, No. 78/Friday, April 21, 2000/Proposed Rules
                                                                      21585
 studies support this conclusion (EPA
 2000a).
   This conclusion indicates that the
 current monitoring screen for Ra-228
 based on Ra-226 is not reliable.
 Therefore as proposed in 1991, EPA is
 considering requiring separate
 monitoring and analysis of both radium-
 226 and radium-228 in the final rule.
 The Ra-228 and Ra-226 results would be
 summed to determine compliance with
 the radium MCL. This will provide a
 more accurate assessment of systems
 containing little or no radium-226, but
 possessing a significant enough
 concentration of radium-228 to exceed
 the standard.

 G. Gross Alpha MCL
   The gross alpha standard promulgated
 in 1976 considered natural and man-
 made alpha emitters as a group rather
 than individually. At the time, the
 analytical costs made it impractical to
 identify each alpha-emitting nuclide in
 a given water sample. The existing gross
 alpha MCL includes radium-226, but
 excludes radon-222 and uranium
 (because these latter nuclides were to be
 regulated at a later date). The 1991 risk
 estimates indicated that the inclusion of
 Ra-226 was not warranted. However,
 today's risk estimates, based on FGR-13
 (EPA 1999b), suggest that the Ra-226
 unit risk is large enough to warrant to
 include it in gross alpha, as in the
 current standard. In today's Document,
 the Agency is considering maintaining
 the current MCL for gross alpha,
 believing it to be protective. EPA will
 consider proposing changes to the rule
 in the future.
  EPA believes that the term "gross
 alpha" may be confusing.  "Gross alpha"
 implies counting the total alpha
 emissions and is the appropriate name
 for that particular analytical method.
 The standard excludes uranium and
 radon from the total or gross count. Just
 as the proposal suggested the term
 "adjusted gross alpha" with the
 exclusion of radium-226, EPA believes
 the term "net alpha" or "the alpha
 standard" might better describes the
 current standard which excludes such
 alpha emitters as radon, uranium. EPA
 requests public comment on the name
 change.
  The gross alpha MCL was originally
 established at 15 pCi/L to account for
 the risk from radium-226 at 5 pCi/L (the
 radium regulatory limit) plus the risk
 from polonium-210, the next most
radibtoxic element in the uranium
 decay chain. In 1976, the risk resulting
from exposure to 10 pCi/L of polonium-
 210 was thought to be equivalent to the
risk resulting from exposure to 1 pCi/L
of radium-226. Looked at another way,
 the 1976 gross alpha standard equated
 to 6 pCi/L of radium-226 (5 pCi/L of
 radium-226, plus thelO pCi/L of
 polonium-210 which itself was equal to
 1 pCi/L of radium-226). Since the risk
 associated with the combined radium
 standard was believed to be in the range
 of 5xlO~5 to 2xlO~4- this assumption
 placed the gross alpha standard
 reasonably within that range as well.
   The gross alpha standard proposed in
 1991 remained at 15 pCi/L, but
 excluded radium-226 (because it was
 proposed at 20 pCi/L). The new limit
 was termed "adjusted gross alpha." In
 effect, it allowed an increase of 5  pCi/
 L of non-radium alpha emitters in
 drinking water from 10 to 15 p'Ci/L by
 occupying the 5 pCi/L originally
 represented by the radium. In the 1991
 proposal, the allowable non-radium
 gross alpha contribution in that same
 water sample i.e. Po-210, would be 15
 pCi/L. Because this latter scenario •
 represents more risk than the scenario
 evaluated for the current regulation,
 EPA no longer supports an  "adjusted
 gross alpha" limit of 15 pCi/L.
   In the future, EPA may consider a
 proposal to exclude radium-226 from
 the gross alpha MCL as proposed in
 1991 (because of the existence of a
 separate standard for radium-226), but
 to maintain protection, limiting the
 gross alpha standard to 10 pCi/L.
 Reducing the limit has the advantage of
 effectively reducing exposure to
 polonium-210 and radium-224. In
 addition, excluding radium-226 from
 being in both the gross alpha and
 radium standards may avoid confusion.
 EPA examined the possibility of this
 change in the context of the potential for
 added treatment costs versus the
 marginal benefits to be derived.
 However it appears that retaining the
 standard at 15 pCi/L is protective of
 public health at a reasonable cost. A
 picoCurie cap of 15 represents different
 risks for various nuclides, but this is not
 unlike other regulated carcinogens or
 the other radionuclides. The risks
 represented by two components, namely
 radium-224 and Polonium-210, are
 discussed next.

 1. Polonium-210
  Current risk estimates suggest that the
 risk resulting from exposure to
 polonium-210 is ten times greater than
 originally believed in 1976 compared to
 radium. However, existing occurrence
 data indicates that its presence in
 drinking water is relatively rare. To gain
a better understanding of the public
health risk posed by polonium-210 in
drinking water, EPA included this
radionuclide in the Agency's
Unregulated Contaminants Monitoring
 Rule (64 FR 50556, Friday, September
 17, 1999). The Agency may consider a
 future proposal to develop a separate
 limit for polonium-210 within (or
 separate from) a potentially revised
 gross alpha standard.
   EPA believes that current technology
 can limit polonium-210 to 4 pCi/L or
 below, although precise quantification
 at this level may present a challenge.
 Because of its energetic alpha emissions,
 a gross alpha measurement may
 overestimate the actual concentration of
 polonium-210 in the sample by a factor
 of two. With current gross alpha
 measurement, if the total alpha were 15
 pCi/1 contributed by polonium, the
 actual concentration of polonium could
 be much less, depending on the
 calibration standard. At present, since
 there is no specific drinking water
 regulation for polonium-210, there is no
 EPA-approved method for measuring
 polonium to determine compliance with
 a drinking water standard. Should EPA
 decide to develop a separate limit for
 polonium-210, the Agency will ensure
 that the  approved analytical method for
 demonstrating compliance is in place
 and includes a calibration  standard
 appropriate for polonium's energetic
 alpha, thereby reducing the possibility
 of overestimating its presence. EPA
 requests information relative to any
 known occurrence of polonium arid the
.need for a proposal of a separate limit.
 Recently, USGS co-operated with EPA
 and the American Water Works
 Association in monitoring  for
 radionuclides, including Po-210 (103
 wells in  27 States). The study and
 findings  are described in EPA 2000a).
 USGS will publish the study in the near
 future. In this study, Po-210 levels were
 found above 1 pCi/L in less than two
 percent of the wells. Since the wells
 were targeted for high radium
 occurrence, this may not be typical. The
 reader is referred to appendix I
 (Occurrence) and the Technical Support
Document (EPA 2000a) for further
 information.

 2. The Occurrence of Radium-224 and
its Impact on Alpha
   Recently, the short lived  isotope of
radium has been found  in some
drinking  water supplies. Extensive
monitoring in the State  of New Jersey
over the past several years and follow-
on survey by EPA and the USGS has
demonstrated that radium-224 may be
present in significant quantities in
ground water, especially where its
decay chain ancestor radium-228 is
present. Although it is included in the
(gross) alpha MCL, it was not targeted
specifically for several reasons: (1) It
was not believed to be a health risk, (2)

-------
21586
Federal Register/Vol.  65, No. 78/Friday, April 21, 2000/Proposed Rules
it was not known to be prevalent and (3)
sampling it at a representative point
within the distribution system rather
than the entry point to the system
allowed decay. However, newer FGR—13
risk estimates (EPA 1999b), coupled
with the greater occurrence, and the
1991 proposal to sample at the entry
point to the distribution system, now
make radium-224 a concern.
  Radium-224 is a naturally occurring
radioisotope, which is part of the
thorium decay chain. It emits alpha
particles and has a  half-life of 3.66 days.
The decay of its progeny via alpha and
beta  decay also happens very quickly. In
approximately 4.1 days, an original
radium-224 atom has decayed to stable
lead-208 by emission of an equivalent of
4 alpha and 2 beta particles. A gross
alpha analysis will detect 3 alpha
particle emissions including daughters
in equilibrium with the parent Ra-224.
If a sample analysis is done within 72
hours,  preferably 48 hours, an
appropriate back-calculation can be
performed of the gross alpha count of
the sample water. Otherwise the
laboratory will significantly
underestimate the radium-224 and other
alpha emitters that may have been
originally present in the sample.
  Under the current rule, utilities are
allowed to collect quarterly samples,
composite and analyze at the end of the
year. In 1991, EPA  proposed a holding
time of 6 months for gross alpha.
However, neither the annual composite
under the current rule or the proposed
holding time of 6 months can
appropriately capture the presence of
alpha-emitting radium-224, or its
progeny in a gross alpha analysis. The
Agency intends therefore, to issue a
separate proposal to change the holding
time for gross alpha analysis to account
for the presence of radium-224 in the
sample.
  At this point in time, the Agency
strongly recommends to States and
utilities that an alpha analysis be
performed within 48  to 72 hour after
sample collection to capture the
contribution of the alpha particles
arising from radium-224. In this NODA,
the Agency is reiterating and
underscoring its recommendation to
that  effect as outlined in a memorandum
of January 27,1999 from Cynthia
Dougherty, Director of the Office of
Ground Water and Drinking Water (EPA
1999a). For systems to whom a rapid
analysis might be a burden, a reasonable
screening tool for the presence of Ra-224
under many geochemical circumstances
is the presence of its  radiological
ancestor, Ra-228. Since systems will
monitor for Ra-228, the result can serve
as a general proxy for the presence or
                    Ra-224 for the purposes of
                    prioritization. It is not definitive and
                    would not be an acceptable substitute
                    for a rapid analysis of gross alpha or Ra-
                    224. In the absence of Ra-228, a system
                    may not need to place as high a priority
                    on rapid gross alpha or specific Ra-224
                    analysis. Since, as explained earlier,
                    each Ra-224 atom contributes
                    approximately three daughter alpha
                    particles to the gross alpha count, a
                    simple first approximation of Ra-224's
                    contribution to gross alpha would be
                    three times the Ra-228 concentration in
                    pCi/L. For the purposes of prioritizing
                    monitoring for Ra-224, grandfathered
                    gross alpha data added to three times
                    the result of the Ra-228 measurement
                    would be a reasonable first
                    approximation of the gross alpha
                    including Ra-224  and its daughters
                    available from a rapid gross alpha test.
                    However, EPA reiterates that this
                    approximation is  not a substitute for .
                    rapid analysis of gross alpha or Ra-224.
                       EPA is not considering requiring a
                    separate MCL or analysis for radium-224
                    when the rule is finalized in November
                    of 2000. The definition of gross alpha
                    will continue to include Ra-224. EPA is
                    willing to consider comments on the
                    need to apply sub-limits to Po-210 or
                    Ra-224 within the MCL of 15 or as
                    separate standards. Proposing a separate
                    limit for radium-224 at 10 pCi/L within
                    the alpha MCL of 15 pCi/L is a future
                    possibility, as is a separate MCL for
                    radium-224. The latter would require a
                    separate, specific, rapid analysis
                    specifically for radium-224, rather than
                    relying on the gross alpha test and alpha
                    MCL. Such actions would require a new
                    proposal or proposals.
                       As part of the alpha standard, the
                    Agency does not consider Ra-224 a
                    significant risk. The lifetime mortality
                    risk associated with exposure to 10 pCi/
                    L of radium-224 is approximately 5 x
                    10 ~5 or one in 20,000. Because radium-
                    224 and its progeny have very short
                    half-lives, the total alpha count
                    represents the radium-224 and its
                    progeny. Consequently, there are
                    effectively three alpha particle counts
                    for every atom of radium-224 present.
                    The health risk of radium-224 already
                    includes the impact of these progeny in
                    the body (the committed do.se).
                    Therefore while the gross alpha count
                    may be at 15, the  impact of the
                    emissions is approximately related to
                    Ra-224 at 5 pCi/L and the risk of 2.5 x
                    10 ~5 or excess mortality of one in
                    40,000.
                    H. Uranium
                       Uranium is not currently regulated by
                    the 1976 radionuclides drinking water
                    standards. The  1986 SDWA
Amendments included uranium as one
of the 83 contaminants listed to be
regulated in drinking water. Two health
effects are associated with exposure to
uranium: cancer, resulting from the
radioactive emissions, and kidney
toxicity, resulting from the exposure to
the uranium itself. The mass of the
uranium is measured in micrograms (ug)
while the radiation activity is measured
in picoCuries. In 1991, EPA proposed a
limit on uranium of 20 ug per liter (ug/
L) to protect against kidney toxicity. The
corresponding radioactivity limit was
assumed to be 30 pCi/L. At that time,
the Agency also proposed an MCLG of
zero, based on absence of an identifiable
dose-response threshold. EPA has
reevaluated both the health impact level
for kidney toxicity and the cancer risks
from radiation and costs of regulation.
As discussed briefly next, the best
estimate of the cost per cancer case or
cancer death avoided at 20 ug/L is
relatively large.  However, it should also
be noted that this cost per case avoided
excludes the reduction in kidney
toxicity risk. At the present time, kidney
toxicity for uranium must be treated as
a non-quantifiable benefit (see appendix
II, "Health Effects" and the Technical
Support Document, EPA 2000a).
  Today's NODA presents new
information which supports a regulatory
level of 20 |ig/L, based upon protection
from kidney toxicity. The derivation of
this number is based on newer, more
complete studies which have also
resulted in a lower uncertainty factor,
now 100-fold. In addition, the
contribution to ingestion from drinking
water relative to food or inhalation, the
relative source contribution (RSC), has
been recalculated. Drinking water is
now considered to contribute 80 percent
of a person's total daily uranium intake.
This has the effect of permitting 80% of
the reference dose (RfD) to be occupied
by the drinking water component of
diet. Both a lower uncertainty factor
coupled with a lower food intake and
higher proportional contribution from
drinking water to total intake, might
suggest the allowance of a higher
regulatory limit; however, the more
recent studies have offset this by
revealing a lower observed effect level
for kidney toxicity. The recalculated
"safe level" for  kidney toxicity remains
20 ug/L. The derivation of the
uncertainty factor is based on the types
of uranium health data available. EPA's
policy for uncertainty factors for
estimating LOAELs is summarized in 63
FR 43756 (August 14,1998, "Draft
Water Quality Criteria Methodology
Revisions: Human Health"). The
derivation is described in appendix II.

-------
                    Federal Register'/Vol. 65, No. 78/Friday, April 21,  2000/Proposed Rules
                                                                      21587
   Uranium is also classified as a
 carcinogen because of its radioactivity,
 and resulting emissions of ionizing
 radiation. The two most prevalent
 isotopes of uranium, uranium-234 and
 uranium-238, have very different half-
 lives which result in different amounts
 of radiation emitted per unit mass.
 Uranium-234 emits far more
 radioactivity than U—238, but is much
 less abundant in aquifer materials.
 Uranium-238 emits less radioactivity,
 but is far more prevalent than U-234.
 The average ratio of uranium activity to
 mass in rock is 0.68 picoCuries per ug.
 Issues involving the activity to mass
 ration follow later in this section.
   Complicating the Agency's decision
 making about a uranium standard is the
 fact that the monetized benefit of kidney
 toxicity cannot be calculated at low
 concentrations because data are lacking
 in terms of the level at which kidney
 disease is actually manifested. The
 calculated 20 ug/L level represents an
 intake which would result in no effect
 over 70 years by drinking two liters per
 day. Conclusions based on the toxicity
 of uranium to the kidney are based
 primarily on observed adverse effects at
 the cellular level, but which have not
 necessarily resulted in a recognized
 disease. It is difficult to monetize the
 benefits derived in such a situation, and
 EPA does not currently have a
 methodology for estimating benefits for
 kidney toxicity from uranium. In the
 case of reducing the risk of non-fatal
 cancer resulting from  uranium, EPA can
 monetize these benefits based on
 avoided "cost of illness." This
 methodology is discussed in some detail
 in the Technical Support Document
 (EPA 2000a) and elsewhere (EPA
 2000b).
   Thus, for kidney toxicity, the benefit
 to society are considered as "non-
 quantifiable benefits." Kidney toxicity
 avoidance benefits can be expressed in
 terms of "avoidance of exposure," but
 cannot be quantified in terms of
 avoidance of a specified number of
 cases of disease or fatalities (and the
 associated monetized benefits), as with
 cancer. In addition, it  appears that
 excess uranium concentrations tend to
be found in small water systems. This
suggests that while many systems will
be impacted, the affected populations
will be small. In terms of cancer risk,
the number of statistical cases avoided
for MCLs of 20 and 40 ug/L are low (0.2
to 2 cases for 20 ug/L and 0.04 to 1.5
cases for 40 ug/L]. In terms of exposure
avoided for kidney toxicity, around 500
thousand to two million persons are
exposed above 20 ug/L and 50 thousand
to 900 thousand persons are exposed
above 40 ug/L. See appendix V and the
 Technical Support Document (EPA
 2000a) for details.
   Although uranium is treatable to
 levels well below the 1991 proposed
 MCL of 20 ug/L (5 pCi/L was evaluated),
 EPA determined that levels below 20
 pCi/1 were not feasible under the
 SDWA, after taking the costs of
 treatment into consideration. Section
 1412(b)(6) of the 1996 SDWA permits
 the Agency to evaluate whether the
 benefits of regulating at various MCLs
 justify the costs. Possible exercise of this
 authority is discussed in more detail
 later in this section.
   The MCLG that was proposed for
 uranium in 1991 was zero because of
 concerns  about the lack of a known
 threshold for the carcinogenicity of
 ionizing radiation. The MCL that was
 proposed in 1991 (20 ug/L) was based
 on uranium kidney toxicity, as
 previously described. The
 corresponding risk of cancer at a
 concentration of 20 ug/1 is now
 estimated to be approximately 5 x 10 ~5.
 In terms of the cost per cancer case
 avoided and kidney toxicity reduced,
 the cost of regulation is still  relatively
 high (see  Table V-2 in appendix V).
   In its current benefit-cost analysis,
 EPA also  evaluated regulatory options of
 uranium MCLs of 40 ug/L and 80 ug/L.
 EPA estimates that a level of 40 ug/L
 would correspond to a cancer risk of
 approximately a 1 x 10 ~4, thus
 providing cancer risk protection within
 the Agency's traditional risk range. A
 level of 40 ug/L would represent a
 slightly higher risk of kidney toxicity.
 At a level of 80 ug/L, the cancer
 mortality  risk is approximately 2 x
 10 ~4, which is above the Agency's
 acceptable risk range. At 80 ug/L, the
 projected  total national costs decrease
 significantly, but the estimates of cancer
 cases avoided drops to values close to
 zero (i.e.,  benefits diminish
 considerably), indicating that the cost
 per cancer case avoided may not  be
 signficantly lower at an MCL of 80 ug/
 L than at an MCL of 40  ug/L. From a
 health effects perspective, the toxic
 health effects on the kidneys or other
 organs or  systems in the body at
 exposure levels of 80 ug/L is unknown
 and is four times EPA's best estimate of
 the "safe level" with respect to kidney
 toxicity.
  In terms of benefits and costs, Table
V-2  (appendix V) shows the range of
 compliance costs and net benefits for
the uranium MCL options of 20 ug/L, 40
ug/L, and  80 ug/L. While annual
compliance costs drop significantly as
the MCL increases from 20 up to 80, the
estimate of cancer cases avoided drops
considerably  also. In fact, it is not clear
whether the cost per case avoided
 increases or decreases with increasing
 MCL because of the uncertainties
 involved. The corresponding estimate of
 cases avoided for MCLs of 20,40, and
 80 pCi/L are 2.1,1.5, and 1.0 cases
 annually. Based solely on cancer
 incidence, it may be appropriate for
 EPA to consider using an MCL higher
 than 20 ug/L for uranium, since it is
 arguable that the benefits do not justify
 the costs at this level. However, in terms
 of kidney toxicity, 20 ug/L may be
 justified. EPA solicits comment on this
 issue.
   Health effects from uranium also need
 to be evaluated in the context of the
 effects of various uranium species and
 their activity levels. A mortality risk
 level of 5xlO~ 5 translates to 23 pCi/L of
 U-238, 22 pCi/L of U-235, and 21 pCi/
 L of U—234  in drinking water. An "alpha
 spec" analysis of the water would
 determine the fractions of each present
 and a sum of the fractions below 100%
 would meet the MCL. However, this
 level is costly to obtain. Doubling the
 radioactivity limit to 46,44 and 42 pCi/
 L for U-238, U-235, and U-234
 respectively corresponds to a mortality
 risk level of 1 x 10^, which may be
 more acceptable, considering the costs.
 Likewise, a doubling of risk to 2 x 1Q-4
 would again double the picoCurie limits
 of each isotope to 92, 88, and 84 pCi/
 L respectively. However, at these higher
 risk levels, the calculated protective
 limit for toxicity to the kidney may be
 exceeded, depending upon the
 uncertainty factor used.
   By contrast, the relative dissolved
 concentration of the various isotopes of
 uranium will differ markedly from one
 locale to another. The 1991 proposal
 utilized a conversion factor of 1.3
 picoCuries per microgram of uranium to
 convert a 20 ug/L proposed MCL in
 mass units to activity units in
 picoCuries (however, 1991 cost
 estimates were based on the more
 accurate conversion ratio of 0.9).
 Analysis of NIRS data suggest that it
 would have been more appropriate to
 use the  1.3 pCi/ug conversion factor for
 total uranium where concentrations are
 less than 3.5 pCi/L and a 0.9 conversion
 factor for concentrations above 3.5 pCi/
 L (Telofsky 1999). Converting the
 derived MCL option of 20 ug/L from
 mass to activity using a ratio of 0.9 for
 levels above 3.5 ug/L yields
 approximately 18 pCi/L . A statistical
 evaluation of uranium data reveals that,
based on a linear regression of the data,
the appropriate activity based MCL for
 20 ug/L would be 17.3 pCi/L rounded to
 17 pCi/L. Coupled with the knowledge
that the concentration of uranium
isotopes varies from place to place, the
Agency is led to consider an MCL that

-------
21588
Federal Register/Vol.  65, No. 78/Friday,  April 21, 2000/Proposed Rules
is protective in any location against both
toxicity (ug/L) and cancer (pCi/L),
whichever presents the greatest risk.
This can be determined by conducting
isotopic analysis to determine the
relative amounts of each isotope in any
one water system. Once the
concentration ratio is known, a
regulated entity may choose to measure
mass or activity and select whichever
analytical method or methods is most
cost effective.
  For example, if the uranium standard
were 20 ug/L or pCi/L, a gross alpha
measurement screen for uranium could
be used in the following way (EPA
2000c and 2000d).  The analysis breaks
out as follows: if the result is below the
detection limit for gross alpha, neither
uranium measurements by mass or
activity would be necessary since
neither 20 pCi/L nor 20 ug/L could be
exceeded. If the gross alpha test is
between 3 and 5.5 pCi/L, the mass of 20
ug/L could be exceeded if all the activity
were coming from uranium-238.
Therefore a fluroimetric test for uranium
mass concentration (ug/L) or an alpha
spectrometry test for the activities (pCi/
L, converted to ug/L using standard
isotopic conversion factors) of the
various isotopes present would be
necessary to determine the uranium
concentration in ug/L. Because gross
alpha tests may underestimate uranium
by a factor of as much as 3.62, if the
gross alpha test exceeded 5.5 pCi/L
(20+3.62), it is indicative  that the 20
pCi/L limit may be exceeded, and an
isotopic analysis must be done. EPA
solicits comment on these issues.
  EPA is soliciting information and
comment on the data and the
appropriate course of action the Agency
should pursue, given the factors of risk
levels, national cost, number of cancers
avoided, cost per case, cost per death,
and kidney toxicity. EPA is currently
evaluating three regulatory options:
  • Regulate at 20  ug/L and 20 pCi/L
(protective of kidney toxicity using the
Agency standard 100-fold uncertainty
factor for this type  of LOAEL with an
associated cancer risk of approximately
5 x 10 ~5 or five in one hundred
thousand);
  • Regulate  at 40  ug/L and 40 pCi/L
(this is twice the safe level with respect
to kidney toxicity and would reduce the
margin of exposure between the effect
level and the proposed regulatory
standard; with an associated cancer risk
level of 1 x 10~4 or one in ten thousand,
which is the Agency's usual upper
cancer risk target);
  • Regulate at 80  ug/L and 80 pCi/L
(this is four times the safe level with
respect to kidney toxicity and would
further reduce the margin of exposure
                    between the effect level and the
                    proposed regulatory standard; with an
                    associated cancer risk level of 2 x 10 ~4
                    or two in ten thousand, which is above
                    the Agency's usual upper cancer risk
                    target).
                      In summary, EPA believes that 20 ug/
                    L is feasible and is the Agency's
                    preferred option, but may not have
                    benefits that justify the costs. Were a
                    higher level to be chosen, EPA would be
                    exercising its discretionary authority
                    under section 1412(b)(6) to select a level
                    above the feasible level. It should be
                    noted, however, that  there may be
                    considerable non-quantifiable benefits
                    of avoiding exposure to cancer and
                    kidney toxicity. Also, as discussed
                    previously, there is little available data
                    or information about  the effects of
                    kidney toxicity at relatively high
                    exposures and thus, the benefits
                    attributable to avoided illness cannot be
                    quantified. Thus,  the costs may be
                    justified at a more stringent level than
                    would be suggested in light of the
                    currently quantifiable benefits alone. In
                    addition, the Agency generally does not
                    establish regulatory levels outside of its
                    target risk range and, in fact, prefers to
                    set levels at the more protective end of
                    that range (1 x 10~6\ wherever possible.
                    Further, we usually follow Agency
                    guidelines on use of uncertainty factors.
                    For these reasons, the Agency does not
                    favor  an MCL option  of 80 ug/L, but
                    solicits comment  on this and the
                    previously-described regulatory options,
                    together with any supporting rationale
                    or data commenters wish to provide.
                    /. Inclusion of Non-Transient Non-
                    Community Water Systems
                      Today's document  is soliciting
                    comment on several approaches for
                    covering Non-Transient Non-
                    Community (NTNC) water systems.
                    Although current radionuclide
                    regulations do not apply to NTNC water
                    systems, in 1991 EPA proposed
                    extending the radionuclides NPDWRs to
                    include them. Several approaches
                    representing varying  degrees of control
                    are being currently considered for
                    finalization because,  although much
                    more has been learned about NTNC
                    water systems and their customers since
                    1991, there is still very little known
                    about the distribution of the highest
                    levels of radionuclides in their water
                    supplies. Based on the Agency's
                    occurrence estimates, control of some
                    radionuclides in NTNC water systems
                    may not present a meaningful
                    opportunity for health risk reduction.
                    This issue arises as a  consequence of the
                    1996 Amendments to SDWA which
                    allow the Agency to consider whether
                    the benefits of extending coverage to
this category of water systems would
justify the costs (section 1412(b)(6)(A))
and whether such regulation would
provide a meaningful opportunity for
health risk reduction (section
1412(b)(l)(A)(iii)). The Technical
Support Document (EPA 2000a)
presents a "what if analysis for costs
and benefits for NTNCWSs.
  While it is feasible to control
radionuclides in NTNC water systems,
extending regulation to these systems
needs to be considered in light of the
new SDWA requirements. This analysis
requires a balancing of both quantitative
and non-quantitative factors. Based on
the risk modeling discussed in the
Technical Support Document (EPA
2000a), the ninetieth (90th) percentile
lifetime risk of cancer incidence in an
individual consuming water from a
NTNC water system in the absence of a
regulation is not expected to exceed
three in 100,000 2. The cost per cancer
case avoided to achieve reductions in
these risks would considerably exceed
the hundred million dollar mark if
coverage of the rule were extended to
NTNCs. The associated cost per case
avoided ranges are well above the range
of historical environmental risk
management decisions.
  Relative to community water systems,
NTNC systems have much lower
associated risk levels because most
individuals served by these systems are
expected to receive only a small portion
of their lifetime drinking water exposure
from this source3. This conclusion
holds even using very conservative
assumptions for modeling the NTNC
exposure scenarios. For example, in the
case of school children exposure, the
Agency has conservatively assumed all
impacted children would attend only
schools served by NTNC water systems,
have twelve years of perfect attendance,
and get half of their daily water
consumption at school. For the average
thirteen year old, this scenario implies
half of a liter (over sixteen ounces) every
school day. Even under this very
conservative set of assumptions, the
water consumed by an individual
student is estimated to represent less
  2 Throughout this discussion, exposures and risks
wore only considered for populations potentially
addressable by regulation, i.e. systems with
radionuclides present in excess of the proposed
MCLs for community water systems.
  3 It is important to remember that the risk
assessment for NTNC water systems does not
consider exposure risk from private wells which
may serve some customers at home. EPA recognizes
that the radionuclide levels in some private wells
may exceed the MCLs for CWSs, but this is a non-
controllable factor since private wells arc not
regulated by the Safe Drinking Water Act.

-------
                   Federal Register/Vol.  65,  No.  78/Friday, April  21, 2000/Proposed Rules
                                                                       21589
than five percent of lifetime
consumption4.
  On the other hand, much remains to
be learned about the NTNC water
systems. Little is known about the
extent to which users of the different
NTNC water systems use other water
systems. It is conceivable that some
areas in the country exist where
individuals are subjected to exposure at
a number of different non-community
systems (e.g., day care center plus
school plus factory, etc.). In such
circumstances, individuals would be
exposed to proportionately higher risks
if the water  systems all had elevated
levels. For some individuals, the
exposures could approach levels
observed in corresponding community
water systems.
  This concern is somewhat alleviated
by the fact that NTNC systems generally
serve only a very small portion of the
total population. For example, over
ninety-five percent (95%) of all school
children are served by community water
systems, not NTNC systems. Only a
small percentage of children are served
by NTNC water systems and, of that
group, less than one percent (or less
than one in 2000 of the overall student
population) would be expected to have
individual radionuclides in their water
above the proposed regulatory levels.
Likewise, less than 0.1 percent of the
work force population receive water
from an NTNC water system. With such
low portions of the total population
exposed to any particular type of NTNC
system, the  overall likelihood of
multiple exposure cases in the NTNC
population should also be small.
   Nevertheless, because children are
more sensitive to radionuclides
exposure5, multiple water system
exposure scenarios were considered in
the modeling effort 6. Tables ffl-2 and
III—3 present individual risk estimates
for average and most sensitive
populations among the NTNC water
systems. All of these factors contributed
to the Agency's evaluation of whether or
not to extend regulation to NTNC water
systems and are discussed further in the
appendix.
  Review of Table III-3 shows that 90th
percentile individual risk patterns for
NTNC water system users exposed to
uranium or radium-226 are relatively
low. These 90th percentile figures
represent risks estimated using the
previously described conservative
exposure scenarios, maximum water
consumption patterns, and what are
effectively 99.9th percentile occurrence
estimates 7 from the NIRS data. Even
with these conservative factors, lifetime
cancer risks do not exceed the one in
10,000 level which has traditionally
formed the upper bound of allowable
risk in Agency decision-making.
                  TABLE III-2.—SELECTED SECTOR AND OVERALL NTNC, INDIVIDUAL RISK PATTERNS
                               [Lifetime cancer risk for individuals using average consumption levels]
Sector
School Students .
Day Care Children 	
Factory Worker
All NTNC Water Systems 	
Alpha
2x10-5
2-3x10-5
1-2x10-5
0.3-0.4x10-5
Radium 226
09-1 1 x10~5
0.6-0.7x10-5
1x10-5
0.2-0.3x10-5
Radium 228
2 3x10-5
2-3x10-5
2 3x10-5
0.5-0.7x10-5
Uranium
07-09x10-5
08-1x10-5
1x10-5
0.2x10-5
  Note that Radium 224 is being used as a surrogate for alpha emitters.

                  TABLE ni-3.—SELECTED SECTOR AND OVERALL NTNC, INDIVIDUAL RISK PATTERNS
                            [Lifetime cancer risk for individuals using 90th percentile consumption levels]
Sector
School Students
Day Care Children
Factory Worker
All NTNC Water Systems

Alpha
05-06x10-"
07-08x10-*
05-06x10-*
02x10~*

Radium 226
03x10-"
02x10-*
0 3— 04x10~4
0 1x10-"

Radium 228
06-07x10-*
0 6x10-*
0 7—0 8x10~*
02-03x10"*

Uranium
0 3x10~4
0 3-04x10"*
0 5-0 6x10~*
0 1—0 2x10~*

  Radium-228 and gross alpha pose
approximately twice the threat of the
other two radionuclides. While sensitive
individual estimates still fall below the
one in ten thousand range, they may not
in a scenario in which other drinking
water sources are similarly high.
However, as stated previously, the
Agency views it as somewhat
improbable that this system overlap
occurs to a significant extent.
Nevertheless, it could be an issue in
some rural communities. While such
  4 Day care exposure is similarly conservatively
estimated by assuming five years of perfect
attendance, fifty weeks per year and five days per
week. Factory workers arc assumed to perfectly
attend and work at the same facility for forty-five
years. Ail of these assumptions arc under
continuing investigation and will likely be revised
downward in the future as the Agency is able to
gather further information.
infrequent and highly site-specific
conditions are very difficult to address
efficiently in a National-level regulation,
the Agency believes that exempting
NTNC water systems from the
radionuclide NPDWRs, given the degree
uncertainty about the occurrence levels
and extent of system customer overlap,
may be inappropriate. For these reasons,
the Agency believes it may be
appropriate to take a somewhat different
approach with respect to NTNC water
systems than previously practiced.
  EPA is considering extending partial
coverage of the radionuclide NPDWRs
to NTNC water systems under several
possible scenarios. Under the first three
options, NTNC systems would be
subject to targeted radionuclide
monitoring requirements, in which
selected NTNC systems would follow
the radionuclides monitoring
requirements for community water
systems. The targeting strategy would be
based on small community water system
occurrence for the same radionuclides.
  5 As an example, the lifetime risk per pCi/L of Ra-
228 to a child whose exposure begins under the age
of five is more than ten times greater than the
lifetime risk of an individual whose exposure
begins between the ages of 25 and 30.
  "For example, the possibility that a child spent
five years in a day care center, then twelve years
in schools, and then forty-five years working in a
factory served only by NTNC water systems with
high radionuclide levels.
  7 In other words, the expected number of NTNC
systems nationwide would be less than twenty. It
is because these levels are so rare that the level is
fairly speculative. As discussed in the appendix,
the Agency believes its estimates of occurrence arc
reasonable, based on levels observed in small
ground water community water systems.

-------
21590
Federal  Register/Vol. 65, No.  78/Friday, April  21,  2000/Proposed Rules
The States (or primacy agency) would
determine which NTNC systems are
likely to be using contaminated water
systems, based on CWS monitoring
results. These systems may then be
required to monitor and meet CWS
MCLs for gross alpha and combined
radium and other relevant
radionuclides. EPA is considering:
  • Requiring targeted NTNC systems to
monitor and meet the CWS MCLs for all
or selected radionuclides, where
targeting is determined by the State
based on whether the NTNC system is
using source water for which CWSs
have reported MCL violations for
radionuclide in question;
  • Requiring targeted NTNC systems to
monitor and post notice if the system
exceeds the CWS MCL, using the same
definition of targeting as  in the first
option;
  • Issuing guidance that recommends
that targeted NTNC systems monitor
and meet the CWS MCLs, using the
same definition of targeting as in the
first option.
  The Agency requests comments on
these options and any supporting
rationale for such a decision. The
Agency is also interested in receiving
comments on other options such as
extending full coverage of the rule to
NTNCs and not extending any aspect of
the radionuclides NPDWRs to NTNC
systems. The Agency will decide,  as
part of the upcoming finalization of the
1991 proposal, to incorporate what it
considers to be the most appropriate
option in view of available the data and
information.
/. Analytical Methods
  Today's NODA provides a brief
update of the methods-related items
which have occurred since the 1991
proposed rule. For a more thorough
discussion of the analytical methods
updates, the public is referred to
appendix in of this NODA and to the
Analytical Methods section of the
Technical Support Document for the
Radionuclides Notice of Data
Availability (EPA 2000a).
1. Radionuclides Methods Updates
  On July 18,1991 (56 FR 33050; EPA
1991), the Agency proposed to approve
fifty-six methods for the measurement of
radionuclides in drinking water
(excluding radon). Fifty-four of the fifty-
six were actually approved in the March
5,1997 final methods rule (62 FR 10168;
EPA 1997a). In addition to these fifty-
four, EPA also approved  12
radiochemical methods, which were
submitted by commenters after the 1991
proposed rule. Currently, an overall
total of 89 radiochemical methods are
                    approved for compliance monitoring of
                    radionuclides in drinking water. These
                    methods are currently listed in 40 CFR
                    141.25.
                     The March 5, 1997 Federal Register
                    also approved suitable calibration
                    standards for the analysis of gross alpha-
                    emitting particles and gross beta-
                    emitting particles. These specific
                    methods-related items are addressed in
                    some detail in the Technical Support
                    Document for the Radionuclides Notice
                    of Data Availability (EPA 2000a) and in
                    even greater detail in the 1997 final
                    methods rule (62 FR 10168, EPA 1997a)
                    and the 1991 proposed rule (56 FR
                    33050; EPA 1991).
                     This NODA also notifies the public
                    about the use of the gross beta method
                    for the screening of radium-228. In the
                    1991 proposed rule (56 FR 33050; EPA
                    1991), the Agency would have allowed
                    the use of the gross beta-particle activity
                    method to screen for the presence of
                    radium-228 at the proposed radium-228
                    MCL of 20 pCi/L. For the combined
                    radium-226 and 228 standard of 5 pCi/
                    L (the current standard), the Agency can
                    not recommend the use of the gross
                    beta-particle activity method for
                    screening of radium-228. Instead, a
                    specific analysis for radium-228 would
                    be necessary. Although several methods
                    are currently approved for the analysis
                    of radium-228 in drinking water, the
                    Agency requests comments from the
                    public and supporting documentation
                    regarding other radium-228 methods or
                    method variations which may be able to
                    reach greater sensitivity at the 2 pCi/L
                    level.
                    2. The Updated 1997 Laboratory
                    Certification Manual
                     In the 1991 proposed rule (56 FR
                    33050; EPA 1991), EPA cited the 1990
                    laboratory certification manual's
                    guidance for sample handling,
                    preservation, holding time and
                    instrumentation. In response to the 1991
                    proposed rule, a commenter questioned
                    why the holding time for radioactive
                    iodine was six months, when the half-
                    life of iodine-131  is  eight days. The
                    Agency recognized this typographical
                    error and changed the holding time to
                    eight days in the updated 1997
                    certification manual (EPA 815-B-97-
                    001; EPA 1997d). Table III-2 in the
                    appendix shows the updated guidance
                    for sample handling, preservation,
                    holding times, and instrumentation that
                    appeared in this manual. Table III-2 in
                    the appendix also includes additional
                    recommendations for radiochemical
                    instrumentation (footnoted by the
                    number 6). The Agency is seeking
                    comment about the additional
                    recommendations found in Table III-2.
3. Recommendations for Determining
the Presence of Radium-224

  To determine the presence of the
short-lived radium-224 isotope (half life
-3.66 days), the Agency recommends
using one of the several options
discussed in the appendix III. Although
these measurement options are only
recommendations, the Agency strongly
urges water systems to check for the
presence of radium-224 in their
drinking water supplies. Comments are
solicited from the public about the
options listed in appendix III or any
other appropriate methods of detection.

4. Cost for Radiochemical Analysis

  Revised Cost Estimates for
Radiochemical Analysis.
  In the 1991 proposed rale (56 FR
33050; EPA 1991), EPA cited cost
estimates for radiochemical analyses.
The Agency updated these costs
estimates by surveying a small number
of radiochemical laboratories (no more
than 9 laboratories) (EPA 2000a). The
revised cost estimates are shown in
Table III-3 (appendix III). Because this
information is based on a limited
number of laboratories, the slight
increase in costs from 1991 to 1999 may
be due to either statistical uncertainty or
possibly others factors such as inflation.
  After the 1991 proposed rule, there
were several comments regarding
analytical costs. One commenter stated
the costs of analysis for radium-226,
radium-228, radioactive strontium and
total strontium were unrealistically low.
The Agency can neither agree nor
disagree. As noted earlier, EPA revised
the cost estimates for radiochemical
analysis. Both the 1991 costs estimates
and the revised cost estimates were from
small surveys and may not be truly
representative of the actual costs for
some radiochemical analyses.
Comparison of the estimated costs from
1991 with the revised cost estimates
indicate the costs for some analyses to
similar, while for other analyses, cost do
appear to be higher. The Agency solicits
comments and factual data that would
clarify this matter.
  Several commenters stated that small
systems, which are likely to need only
a few analyses, cannot take advantage of
rates for volume sample analyses. The
Agency agrees that individual small
systems may not be able to take
advantage of lower bulk analysis costs.
To alleviate cost burdens, small systems
may want to consider pooling their
analytical needs with other small
systems to negotiate for bulk rates.

-------
                   Federal Register/Vol. 65, No.  78/Friday, April  21,  2000/Proposed Rules
                                                                     21591
 5. Externalization of the Performance
 Evaluation Program
   Due to resource limitations, on July
 18, 1996 (61 FR 37464; EPA 1996b),
 EPA proposed options for the
 externalization of the PE studies
 program (now referred to as the
 Proficiency Testing or PT program).
 After evaluating public comment, in the
 June 12,1997 final notice EPA (62 FR
 32112; EPA 1997b):
 decided on a program where EPA would
 issue standards for the operation of the
 program, the National Institute of Standards
 and Technology (NIST) would develop
 standards for private sector PE (PT) suppliers
 and would evaluate and accredit PE
 suppliers, and  the private sector would
 develop and manufacture PE (PT) materials
 and conduct PE (PT) studies. In addition, as
 part of the program, the PE (PT) providers
 would report the results of the studies to the
 study participants and to those organizations
 that have responsibility for administering
 programs supported by the studies.
  EPA has addressed this topic in
 public stakeholders meetings and  in
 some recent publications. For more
 information, readers are referred to the
 aforementioned Federal Register
 notices. More information about
 laboratory certification and PT (PE)
 externalization can be accessed at the
 OGWDW laboratory certification
 website under the drinking water
 standards heading (www.epa.gov/
 safewater). At this time, it is difficult to
 ascertain how and if externalization of
 the PT program will affect
 radiochemical laboratory capacity and
 the cost of radiochemical analyses, hi
 the absence of definitive cost estimates,
 the Agency solicits public comments on
 this subject.
 6. The Detection Limits as the Required
 Measures of Sensitivity
  In 1976, the National Primary
 Drinking Water Regulations defined the
 detection limit (DL) as "the
 concentration which can be counted
 with a precision of plus or minus 100
 percent at the 95 percent confidence
 level (1.96 
-------
21592
Federal  Register/Vol. 65, No.  78/Friday, April 21, 2000/Proposed Rules
to the current rule's framework and
propose to correct deficiencies via a
proposal which will address analytical
method issues as well, such as methods
for Ra-224, Po-210 and Pb-210.
2. Standardized Monitoring Framework
  Per the current rule, once the
contaminant concentration in the water
is established by the average results for
four consecutive quarterly samples or by
suitable grandfathered data, a system
would be categorized as to whether it
was above or below 50% of the MCL for
that contaminant. In accordance with
the SMF, as proposed in 1991, EPA is
suggesting a tiered frequency for alpha
emitters, combined radium, and
uranium. This would entail one sample
every three years for compliant systems
with annual average contaminant levels
above 50% of the MCL. For compliant
systems with annual average levels
below 50% of the MCL for these
contaminants, one sample would be
required every 6 years; non-detects, one
sample every 9 years. EPA believes this
system would align with the
standardized monitoring framework,
and would provide regulatory relief for
systems ivith low to very low levels
(without needing a waiver as called for
in 1991). It would also provide more
careful screening for systems with
multiple sources of water entering the
distribution system, by requiring a
sample at each of these points to be
protective of all of the customers within
each water system. For beta particle and
photon radioactivity, EPA is considering
requiring four consecutive quarters
every four years, the requirement under
the current rule, for vulnerable systems
because of their proximity to
contamination sources.
  EPA believes this monitoring scheme
is less burdensome on systems in the
long term than either the existing or
proposed regulations. It provides
slightly more protection than the
current rules by more frequent
monitoring for contaminants above half
the MCL, and less frequent monitoring
for the vast majority of systems below
half the MCL. EPA believes this is more
realistic and less burdensome, while
recognizing the potential for variability
of naturally occurring radionuclide
levels in ground water over time. Such
variability (e.g., a change in pH by
nitrogen fertilizer application leading to
a higher solubility of radium) was seen
in New Jersey and is further discussed
in appendix I.
  Small ground water systems comprise
the vast majority of systems with
radionuclide contamination problems.
Since most small systems have only one
entry point, an entry point monitoring
                    requirement will not have an impact.
                    For systems with radium above 50% of
                    the MCL, with three or fewer entry
                    points to the distribution system,
                    monitoring at each entry point once
                    every three years would have an equal
                    or smaller impact (in terms of the
                    number of samples analyzed) than the
                    1976 requirement of monitoring four
                    times every four years.
                    3. Entry Point Monitoring
                     EPA recognizes that sampling
                    conducted at the monitoring location
                    specified in the current rule may under-
                    represent the risk to some consumers.
                    Results can vary depending on the usage
                    of each water source and changes in the
                    monitoring location within the
                    distribution systems. For systems with
                    more than one water source, monitoring
                    within the distribution system may
                    yield different results. In the current
                    rule, sampling is conducted "at a free
                    flowing tap" within the distribution
                    system. The current rule also recognizes
                    the potential problems by providing that
                    systems with two or more sources of
                    water with different concentrations of
                    radionuclides monitor the source water,
                    as well as water from a free flowing tap,
                    when ordered by the State. Entry point
                    monitoring, a feature of more recent
                    NPDWRs, provides a better measure of
                    water quality for residents near the start
                    of the distribution system than
                    monitoring within the distribution
                    system (e.g., the middle of the system)
                    where water is subject to blending if
                    there are other sources. Therefore, EPA
                    proposed in 1991 to change the location
                    for compliance monitoring to the entry
                    points to the distribution system,
                    consistent with other NPDWRs.
                    4. Grandfathering Data
                     In the implementation guidance,
                    which will be available on OGWDW's
                    home page (http://www.epa.gov/
                    ogwdw), EPA is suggesting that samples
                    within the latest compliance period,
                    beginning June, 1996, be eligible for use
                    in determining the baseline  for
                    monitoring frequency. While EPA
                    prefers this approach, others may be
                    possible. Please provide data and
                    supporting rationale if you comment on
                    this issue. The application of this
                    provision would extend to all classes of
                    radionuclides for which data are
                    available.
                     The Agency solicits comment on two
                    different approaches for the beta
                    monitoring requirements. The first
                    option is to not allow any reduced
                    monitoring and the second would be to
                    allow reduced monitoring similar to the
                    alpha emitters. If systems must collect
                    samples on a quarterly basis (no
reduced monitoring) then
grandfathering of data is not necessary.
If the Agency decides to allow reduced
monitoring, the Agency believes that
States may use historical data to
supplement their vulnerability
assessments but should not use
grandfathered data to satisfy the initial
monitoring requirements because a
sufficient baseline needs to be
established in those systems considered
vulnerable to man-made radioactivity.
  Grandfathered data would be used to
comply with the initial monitoring
requirements for gross alpha, radium-
226/228, and uranium, under some
circumstances. Data collected after June
1996, during the most recent
compliance period, would be
considered for grandfathering. It would
be the State's responsibility to
determine if grandfathered data is
sufficient to satisfy the initial
monitoring requirements established by
this rule. At the State's discretion,
systems with one entry point to the
distribution system (EPTDS) could use
grandfathered data to satisfy the initial
monitoring requirements. Systems that
have multiple entry points  to the
distribution system could use
grandfathered data collected after June
1996 to satisfy the initial monitoring
requirements, provided that the data
were collected at the EPTDS.
  EPA is also considering that, at the
State's discretion, systems with up to
three entry points to the distribution
system could also use grandfathered
data to satisfy initial monitoring
requirements, even if not collected from
EPTDS, if the State makes a written
finding that the circumstances of the
system and their review of historic data
justify such action. While the Agency
cannot prescribe every possible scenario
that a State may encounter, an example
of circumstances that might support
such a finding could be: a system that
has three wells (and EPTDS), that are
simply from different parts of a well-
field, using the same aquifer, with good
historical data showing  uniform, low to
no radionuclide occurrence from all
wells, perhaps from the raw water as
well as distribution system samples.
5. Sample Compositing
  In general, compositing of samples is
an effective means of decreasing
analytical costs  to systems. Compositing
is permitted for alpha emitters and beta
and photon emitters in the  current rule.
It is also allowed for radium-226 and
-228 to the extent gross alpha was used
as a screen for Ra-226 and, in turn, Ra-
228. In the 1991 proposal, gross beta
compositing was prohibited.
Compositing for other nuclides was

-------
                    Federal  Register/Vol. 65; No. 78/Friday, April 21, 2000/Proposed  Rules
                                                                      21593
 allowed for up to five sampling points
 within one system; if the result for the
 composite was more than 3 pCi/1 for any
 nuclide, individual non-composited
 samples were to be analyzed. This
 provision stemmed from the lowest
 MCL in the 1991 proposal, adjusted
 gross alpha at 15 pCi/1. Because of the
 possibility that one of the five samples
 taken might be at 15 pCi/L even if the
 other four were at zero, the rule
 envisioned one fifth (3 pCi/L)  of the
 MCL as the maximum allowed result to
 assure no single well could exceed the
 MCL. The principle of limiting the
 result of five composited samples from
 separate entry points to one fifth of the
 MCL (or four composites to one fourth
 the MCL etc.) is still valid as a general
 matter, and should be followed
 whenever compositing is done.
   A 3 picoCurie limit in the proposal
 would have been conservatively
 protective for a five sample composited
 for the proposed separate MCLs radium-
 226 and radium-228 at 20  pCi/L each,
 since Vs of each MCL is greater than 3
 pCi/L. However, because EPA  is
 considering retaining the current
 radium standard at 5 pCi/L combined,
 adding the results of five composited
 entry points samples for Ra-228 to the
 results of 5 composited entry point
 samples of Ra-226 must yield a result of
 one tenth (Vio) of the MCL to be assured
 that the combined Ra-226  and Ra-228
 concentration could not exceed the MCL
 at any one entry point. Because one
 tenth of the MCL (0.5 pCi/L) is below
 the detection limit for Ra-226 and Ra-
 228, compositing of separate entry
 points cannot apply in case of Ra-226 or
 Ra228. However, annual compositing of
 samples from the same entry point may
 apply.
  EPA requests comment on the
 feasibility and practical utility  of
 compositing separate entry points
 (spatial compositing) versus
 compositing samples over  time from the
 same entry point (temporal
 compositing): EPA believes that the use
 of one or the other (but never both
 simultaneously) may be appropriate
 under some circumstances. Greater
 certainty in the analytical result is
 obtained by taking the average of four
 separate (non-composited)  results from
 one sampling location than by using a
 single result of composited samples.
 However, where an MCL is sufficiently
 above the detection limit such that
analytical results are not subject to
 significant error near the MCL,
 compositing may be a cost  saving
measure. Additionally, when historical
data indicate that contaminant levels are
negligible (e.g., non-detects) for a water
system, compositing among wells in a
 system or between systems having one
 point of entry may be advisable at State
 discretion. However, because of the
 costs of re-sampling and re-analysis of
 all points to confirm an MCL violation,
 or to qualify for decreased monitoring,
 it may not be in the systems best interest
 to initially composite in the absence of
 historical data.

 6. Increased and Decreased Monitoring
   Additionally, the Agency is
 considering having the final rule allow
 systems that are currently on a reduced
 monitoring schedule to remain on that
 reduced schedule as long as the system
 qualifies  for reduced monitoring based
 on the most current analytical result.
 Systems for which the most current
 analytical result indicates a higher level
 than allowed for that monitoring
 schedule would resume monitoring at a
 frequency consistent with the most
 recent result. For example, a system
 with an annual average below half of the
 MCL could reduce monitoring to one
 sample every 6 years. If, while on this
 reduced frequency, the system collects a
 sample with an analytical result above
 half the MCL, the system would have to
 increase monitoring again to once every
 3 years. It could revert to its previous
 reduced frequency of once  every six
 years if the subsequent analytical result
 (of the sample taken three years later)
 was less than half the MCL. EPA also
 believes it is prudent to require
 quarterly  samples to be. collected at least
 60 days apart, to capture seasonal
 variations. EPA solicits comment on this
 and other monitoring provisions.
 7. Compliance Determinations
   Compliance would be determined
 based on the annual average of quarterly
 samples collected at each entry point for
 all classes of radionuclides. If the
 annual average of any entry point
 exceeds an MCL, the CWS would be in
 violation.  If NTNC systems are subject
 to MCLs, the same situation would
 apply to them. An immediate violation
 would occur for any sample analytical
 result or combination of sample
 analytical results that would place the
 system in  violation before four quarters
 of data are collected (e.g., the first
 sample is  greater than 4 times the MCL
 or the average of the first two samples
 is greater than twice the MCL). If a
 system has a sample that exceeds the
 MCL while on reduced monitoring, it
 would need to begin quarterly
 monitoring the following quarter.
 Compliance would be based on the
 average of the four consecutive quarters
 of data beginning with the initial result
that exceeded the MCL. If a  system fails
to collect all samples required during
 any year, compliance would be
 calculated based on available data.
 Under the current rule, quarterly
 monitoring is continued until the
 annual average concentration no longer
 exceeds the MCL or until a monitoring
 schedule as a condition to a variance,
 exemption, or enforcement action
 becomes effective.
   The following  is a summary of certain
 features of the monitoring requirements
 for each regulated radionuclide or
 radionuclide group.

 8. Combined Radium-226 and -228

   Standardized monitoring: EPA
 contemplates application of the
 standardized 3, 6, 9 year cycles to the
 combined radium standard depending
 on whether analytical results for
 compliant systems are greater than (3) or
 less than (6) half the MCL or are a non-
 detect (9), as previously discussed.
 Decreased and increased monitoring
 would be based on the result of the
 analysis of the most recent required
 sample(s).
  Entry point monitoring: Monitoring at
 entry points to the distribution system
 would be a requirement per the 1991
 proposal unless EPA receives comments
 with compelling reasons for not doing
 so.
  Sample Compositing: To decrease the
 burden of monitoring at distribution
 entry points, EPA is contemplating
 allowance of sample compositing for
 radium-226 or radium-228, but only
 when results will be indicative of the
 true level at a single entry point
 (temporal compositing). According to
 the proposal, systems would be required
 to analyze for Ra-228 separately from
 gross alpha or Ra-226.  The Agency sees
 no reason why four separate samples
 from a single entry point (collected 60
 days apart) could not be either analyzed
 and averaged or composited in the
 laboratory and analyzed, to determine
 future monitoring frequency. Therefore,
 EPA is suggesting for public comment
 that systems take the average analytical
 results from four individual samples, or
 the composite of four samples from each
 entry point, in order to determine future
 frequency.
  As discussed previously, EPA does
 not contemplate allowing compositing
 of multiple entry points for derivation of
 combined radium results. EPA requests
 comment on any element of the
foregoing discussion.
9. Alpha Emitters

  Standardized monitoring: Same as for
combined radium (see previous
discussion).

-------
21594
Federal Register/Vol. 65, No. 78/Friday, April 21, 2000/Proposed Rules
  Decreased and increased monitoring:
Same as for combined radium (see
previous discussion).
  Entry point monitoring: Same as for
combined radium (see previous
discussion).
  Sample Compositing: The current rule
allows compositing of four samples in a
laboratory or the averaging of four
separate analyses. Under the 1991
proposal and the current rule, systems
would be allowed to composite
annually for samples taken from single
entry points (temporal compositing)
and, under the 1991 proposal, to
composite samples representing up to
five entry points with a six month
holding time (spatial compositing).
10. Uranium
  Standardized monitoring, monitoring
frequency, and entry point monitoring:
Same as for combined radium (see
previous discussion).
  Sample Compositing: For systems
with gross alpha levels that are high
enough to warrant uranium monitoring,
annual composites for a single entry
point would be allowed. Compositing of
five samples representing five entry
points would be permitted. If the result
was greater than one fifth of the MCL,
the individual samples would have to
be analyzed or re-sampling and analysis
of the new individual samples would
have to occur.
11. Beta and Photon Emitters
  Standardized monitoring framework,
decreased monitoring: Monitoring for
beta and photon emitters would follow
the same schedule as in the current rule.
Decreased monitoring is not envisioned
for beta and photon emitters since only
vulnerable systems would monitor,
althougbrEPA is taking comment on the
possibility of decreased monitoring
according to the standardized
monitoring framework as outlined
previously.
  Screening levels: EPA recognizes
certain problems with the current and
proposed system. The proposed
requirement of a 30 pCi/L screen for
gross beta and photon emitters had the
effect of no longer requiring Sr-90
monitoring because the proposed limit
was above the screen of 30 pCi/L. Under
the current MCL, there is only one
contaminant that has a concentration
limit near the 50 pCi/L screening level
(Ni-63). There are five contaminants
with concentration limits at or near 30
pCi/L and seven with limits below
                    thirty. A screen level of 50 pCi/L would
                    potentially miss the 12 contaminants
                    with concentration limits below 50 pCi/
                    L and a screening level of 30 pCi/L
                    •would potentially miss the 7
                    contaminants with concentration limits
                    below 30 pCi/L. Systems that are
                    drawing water from sources with known
                    beta particle and photon radioactivity
                    are required to use a screening level of
                    15 pCi/L under the current rule. The
                    1991 proposal retained this feature.
                      EPA thinks it is advisable to retain the
                    proposed monitoring for sites within 15
                    miles of a source of beta photon
                    emitters. The screening level in the
                    original rule only affected surface water
                    systems serving over 100,000, or other
                    systems at State discretion, and the
                    screening level for gross beta reflected
                    this limited regulation. However, a
                    known source of particular beta and
                    photon emitters should be monitored for
                    the specific radionuclides present at
                    that source which may be a health
                    concern below the screen, but would
                    not be triggered by the screen. EPA
                    would give States discretion on
                    requiring specific monitoring for
                    contaminants from specific sources.
                      In addition, a 15 pCi/1 screening level
                    is currently required for systems using
                    water contaminated by effluents from
                    nuclear facilities. These systems may
                    also be required by the State to monitor
                    for individual nuclides on a case by case
                    basis. Since both screens may miss
                    radionuclides of concern, EPA believes
                    this issue is important and may need to
                    be addressed in a future proposal. In
                    addition, since many beta particle and
                    photon emitters have half-lives that are
                    too short to be detected under the
                    current holding time, the issue of
                    sample holding time may have to be re-
                    visited in a future proposal.
                      Holding time: Another issue has a
                    bearing on the screening level for which
                    EPA is requesting comment. There are a
                    significant number of beta and photon
                    emitting radionuclides with short half
                    lives, including those 13 nuclides of
                    concern below the screening levels
                    being considered. Because annual
                    sample compositing is allowed under
                    the current rule for beta and photon
                    emitters, a screen above 30 pCi/L would
                    detect a greater number of nuclides
                    which (due to decay) may have been
                    above a screen of 50 at the time of
                    sampling, but are now between 30 and
                    50 pCi/L by the time of analysis. A
                    screen level at 30 pCi/L would be more
sensitive a screen for beta particle and
photon radioactivity. The Agency
requests comment on the selection of
screening levels.
  Sample Compositing: Annual
compositing is permitted for beta and
photon emitters in the current rule. In
addition, for systems utilizing water
contaminated by effluents from nuclear
facilities, a quarterly compositing of five
consecutive daily samples was to be
analyzed for iodine-131, with more
frequent monitoring at State discretion
if it was detected in the finished water.
EPA believes this compositing for single
nuclide determinations is still valid.
However, the  1991 proposed rule
excluded compositing for beta and
photon emitter samples. It also limited
holding times to 6 months for single
samples or 12 months for composites
per the lab cert manual. A screen above
50 pCi/L , but with a sample holding
time of 6 months without compositing
may be a reasonable approach,
considering screening options, holding
times, and compositing issues. EPA
solicits comment on these beta and
photon emitter monitoring issues.
  Entry point monitoring: EPA solicits
opinion on requiring beta photon
monitoring at entry points to the
distribution system for vulnerable
systems. EPA  believes this is
appropriate as it is for other nuclides,
especially as an early warning of
contamination from a localized source
of man-made beta photon emitters.
12. Monitoring for Non-Transient Non-
Community (NTNC) Systems

  If EPA finalizes an option that
requires monitoring for some or all
NTNC systems, EPA wishes to make the
monitoring requirements consistent
between CWSs and  those NTNC systems
required to monitor. See the previous
discussion for CWS monitoring for
details. As with CWSs, monitoring
under the SMF would be required at
entry points to the distribution system,
based on a nine-year cycle,  consisting of
three, 3-year monitoring periods, with
provisions for reduced monitoring as
appropriate. If the radionuclides
NPDWRs for CWSs are fully extended to
NTNCWSs, the monitoring frameworks
would be the same.
  Table III-4 summarizes the
monitoring frequencies for CWSs and
NTNC systems, under the options that
require monitoring:

-------
                    Federal  Register/Vol.  65, No. 78/Friday, April  21,  2000/Proposed Rules
                                                                      21595
    TABLE 111-4. COMPARISON OF THE MONITORING FRAMEWORKS: THE EXISTING RULE, THE 1991 PROPOSAL, AND THE
                                         APPROACH DESCRIBED IN THE NODA
            Current rule (1976)
              1991 proposal
                                                                                            2000 NODA
                                            Radium Alpha Emitters and Uranium
 Initial baseline: 4 consecutive quarterly samples
 If average > MCL=treat, etc 	
 If one or more  samples  >MCL, do quarterly
  sampling until average < MCL.
 If >50% of MCL, 4 Quarters every 4 years	
 If < 50% of MCL, 1 sample every 4 years

 If no detect, 1 sample every 4 years 	
  Initial baseline: one sample per year for 3
   years.
  Same as 1976 .
  Same as 1976 .
  If >50% of MCL, one sample every 3 yrs or
   waiver to every 9 yrs.
  If <50% of MCL, one sample every 3 yrs or
   waiver to every 9 years.
  If no detect, one sample every 3 yrs or waiver
   to every 9 yrs.
 Initial baseline: 4 consecutive quarterly sam-
   ples  taken within  3 years from effective
   date or grandfathered data in previous com-
   pliance period.
 Same as 1976.
 Same as 1976.

 Same as 1991 with no waiver.

 If < 50% of MCL, one sample every 6 years.

 If no detect, one sample every 9 years.
                                                Beta and Photon Emitters
 Quarterly gross beta-monitoring. Vulnerable
  systems  and surface  water systems  >
  100,000 pop. Screen of 50; screen of 15 for
  contaminated water  1-131  quarterly, Sr-90
  and H-3  annual  Sr-89 and Cs134 if above
  15.
 Vulnerable  systems  (surface  and ground
   water) within 15 miles of  source of man
   made emitters do gross beta  screen  pro-
   posed at 30.
 Same as 199 ^Vulnerable systems within 15
   miles of source of man made emitters will
   monitor with screen of 50 or 30. Same as
   1976: Screen of 15pCi/L for systems using
   contaminated waters. Same contaminants
   as 1976 with corrections per NBS HB-69.
 13. Poloniura-210 and Lead-210
  Risk estimates based on Federal
 Guidance Report No. 13 indicate that
 current screening levels for gross alpha
 and gross beta may not be adequate to
 capture all contaminants of concern.
 Specifically, based on the new health-
 effects information contained in FGR—13
 (EPA 1999b), EPA believes it may be
 appropriate to require systems to
 perform isotopic analyses for additional
 radionuclides that may present a
 significant threat to human health. As a
 result of this information, EPA is
 requiring some systems to do analyses
 for polonium-210 (a naturally occurring
 alpha emitter) and lead-210 (a naturally
 occurring beta emitter) under the
 Revisions to the Unregulated
 Contaminant Monitoring Regulation
 (UCMR) (64 FR 50556, Friday,
 September 17,1999), to be implemented
 after analytical methods for these
 contaminants have been approved.

 14. Reporting Requirements
  On May 13,1999, EPA proposed
 subpart Q. (64 FR 25964) to revise the
 minimum requirements public water
 systems must meet for public
 notification of violations of NPDWRs
 and other situations that pose a risk to
 public health from the drinking water.
EPA anticipates the final Public
Notification Rule (PNR), under part 141,
subpart Q to be published in early 2000.
After the final PNR is published,
subsequent EPA drinking water
regulations that affect public
 notification requirements will amend
 the PNR as part of each individual
 rulemaking.
  The proposed PNR divides the public
 notice requirements into three (3) tiers,
 based on the type of violation. "Tier 1"
 applies to violations  and situations with
 significant potential to have serious
 adverse effects on human health as a
 result of short-term exposure. Notice is
 required within 24 hours of the
 violation. "Tier 2" applies to other
 violations and situations with potential
 to have serious adverse effects on
 human health. Notice is required within
 30 days, with extensions up to three
 months at the discretion of the State or
 primacy agency. "Tier 3" applies to all
 other violations and situations requiring
 a public notice not included in Tier 1
 and Tier 2. Notice is required within 12
 months of the violation, and may be
 included in the consumer confidence
 report at the option of the water  system.
  Today's NODA requests comment on
 whether community water systems
 (CWS) should provide a Tier 2 public
 notice for MCL violations under the
radionuclide NPDWRs and to provide a
tier 3 public notice for violations of the
monitoring and testing procedure
requirements. If NTNC water systems
are required to monitor and notify, then
they would be required to provide a Tier
2 notice if the systems exceed the MCLs.
EPA requests comment on the
implementation of public notification
requirements by the effective date of the
MCL and on the Tier  2 public notice
 requirement for quarterly repeat notices
 for NTNC systems that continue to
 exceed the CWS MCL(s) under the
 "monitoring and notification-only"
 option. EPA believes States will phase
 in monitoring of NTNC systems based
 on results of CWS systems in the same
 proximity. The agency requests
 comment on whether or not the same
 increase or decreased monitoring
 requirements which pertain to CWSs
 should apply to NTNC water systems
 i.e. the 3, 6 and 9 year monitoring based
 on being above 50% of the MCL, below
 50%, or non-detect.
  As in the current rules, an analytical
 result that exceeds the MCL would
 trigger additional confirmation samples,
 which in turn could trigger quarterly
 monitoring. For man-made beta and
 photon emitters, EPA is suggesting to
 finalize the proposal regarding a
 screening level of 30 or 50 pCi/L for
 "vulnerable systems," which are
 defined as being within a 15 mile radius
 of a source of this class of radionuclides.
 For Pb-210, EPA will be collecting data
 to make a future determination
 regarding additional monitoring for this
 natural beta emitter.
  Tables in-5  and III—6 summarize the
 current and proposed monitoring
requirements and those suggested by
today's document.

-------
21596
Federal Register/Vol.  65, No. 78/Friday, April 21,  2000/Proposed Rules
                               TABLE 111-5.—INITIAL (ROUTINE) MONITORING REQUIREMENTS
                   1976
                                     1991 proposal
                                                                                                     2000 NODA
                                                        GROSS ALPHA
CWSs: Four consecutive quarters at represent-
  ative po!nt(s) within the distribution system
  every four years.
                       CWSs and NTNCWSs: Annual monitoring at
                         each entry point for first three years.

                                       RADIUM
CWSs  and  NTNCWSs1:  Four  consecutive
  quarters of monitoring  at each entry point,
  anytime during first 3 years.
CWSs: Four consecutive quarters at represent-
  ative  point(s) within the distribution system
  every four years. Initial monitoring is for ra-
  dium-226. If  radium-226  exceeds  3  pCi/L,
  analysis for radium-228 is required. A gross
  alpha measurement can be substituted for ra-
  dium  226 and/or uranium  monitoring if the
  gross alpha measurement is below the appli-
  cable MCL(s).
                       CWSs and NTNCWSs: Annual monitoring for
                         each radium isotope  (radium-226 and ra-
                         dium-228)  at  each entry  point,  for three
                         years.
CWSs  and  NTNCWSs:  Four  consecutive
  quarters of monitoring for each radium iso-
  tope  (radium-226 and radium-228) at each
  entry point, any time during first 3 years.2
                                                           URANIUM
None
                       CWSs and  NTNCWSs: Annual monitoring at
                         each entry point for three years.
CWSs  and   NTNCWSs:  Four  consecutive
  quarters of monitoring for uranium to deter-
  mine compliance with both mass and activ-
  ity either b.y gross alpha or specific mass or
  activity analysis at each entry point,  every
  three years.2
                                                 BETA AND PHOTON EMITTERS
CWSs serving > 100,000 persons and using
  surface water (and other systems designated
  by the State):  Four consecutive quarters for
  gross beta, tritium and strontium-90 at  rep-
  resentative point(s) within the distribution sys-
  tem. Determine major constituents if exceed
  screen of 50pCi/L Systems using water  con-
  taminated with effluent from nuclear facilities:
  Quarterly  monitoring' for gross beta and io-
  dine-131.  strontium-90  and tritium. If gross
  beta level is  above 15 pCi/L,  the  same or
  equivalent samples must  be  analyzed for
  strontium-89 and cesium-134.
                       Vulnerable   systems   only   CWSs   and
                         NTNCWSs: (as designated  by  State): Two
                         gross beta screening levels  were discussed
                         in the 1991 Proposal. Using a screen of 30
                         pCi/L, quarterly monitoring for gross beta is
                         required,  along  with  annual tritium moni-|
                         taring. Using a screen of 50 pCi/L, quarterly'
                         monitoring for gross beta is required, along
                         with  annual tritium and strontium-90 moni-
                         toring.
Vulnerable   systems   only   CWSs   and
  NTNCWSs: (as designated  by  the  State):
  Two gross  beta14  screening  levels  are
  being considered.  Using a screen of 50 or
  30  pCi/L, quarterly monitoring  for  gross
  beta is required, along with annual  moni-
  toring for tritium  and  strontium-90  as in
  1976. Vulnerability based  on proximity  (15
  miles ) to source per 1991. Screen of 15 for
  contaminated waters as in  1976.3
  NOTE:'This assumes that monitoring will be required at NTNC systems. If this is not the case, these requirements would not apply to NTNC
systems.
  2A gross alpha measurement can be substituted for radium-226 and/or uranium monitoring if the gross alpha measurement is below the appli-
cable MCL(s).
  3 Quarterly monitoring for gross beta would be based on the analysis of monthly samples or the analysis of a composite of three monthly sam-
ples. For iodine 131, a composite of five consecutive daily samples shall be analyzed once per quarter. Additional monitoring may be required to
identify specific isotopes if gross beta measurement exceeds the screening level.

                                   TABLE III-6.—REDUCED MONITORING REQUIREMENTS
                   1976
                                     1991 proposal
                                                                                                     2000 NODA
                                                         GROSS ALPHA
CWSs: One sample every four years if annual
  average from previous results (four consecu-
  tive quarterly samples) is less than Vfe MCL.
                       CWSs  and NTNCWSs:  One  sample every
                         three years, if previous monitoring results
                         (from three  years of annual monitoring) are
                         below MCL. If system  is reliably and con-
                         sistently below MCL, the system could re-
                         ceive  a waiver,  and  monitor  once every
                         nine years.
CWSs and  NTNCWSs: One sample  every
  three  years  if previous monitoring  results
  ("previous results") are reliably and consist-
  ently at or below MCL; one sample every
  six years if previous results are reliably and
  consistently  at or below Vz MCL; or one
  sample every nine years if previous results
  are reliably and consistently at  or below the
  MDL.

-------
                    Federal Register/Vol.  65,  No.  78/Friday, April 21,  2000/Proposed  Rules
                                                                        21597
                            TABLE III-6.—REDUCED MONITORING REQUIREMENTS—Continued
                  1976
                                                       1991 proposal
                                                                                               2000 NODA
                                                        RADIUM
 CWSs: One sample every four years if annual
   average from previous results (four consecu-
   tive quarterly samples) is less than Vz MCL.
  CWSs and  NTNCWSs using ground  water.
    One sample every three years, if previous
    monitoring results (from three years  of an-
    nual monitoring) are below MCL. If system
    is reliably and consistently below MCL, the
    system could receive a waiver, and monitor
    once every nine years.
 CWSs  and NTNCWSs:  One sample every
   three years if previous results are reliably
   and  consistently at or below  MCL; one
   sample every six years if previous results
   are reliably and consistently at or below  V*
   MCL; or one sample every nine years if
   previous results are reliably and consist-
   ently at or below the MDL.
                                                       URANIUM
 None
                                         CWSs  and NTNCWSs:  One sample  every
                                           three years, if previous monitoring results
                                           (from three years of annual monitoring) are
                                           below MCL. If system  is reliably and con-
                                           sistently below MCL, the system could re-
                                           ceive a waiver,  and  monitor once  every
                                           nine years.
                                         CWSs  and  NTNCWSs:  One sample every
                                           three  years  if previous results  average
                                           below MCL; one sample every six years if
                                           previous results average at or below Vz
                                           MCL;  or one sample every nine  years if
                                         •  previous results average below the MDL
                                              BETA AND PHOTON EMITTERS
 CWSs serving > 100,000  persons and using
   surface water (and other  systems designated
   by  the  State): Every four  years,  systems
   must collect samples from four consecutive
   quarters for gross  beta at representative
   point(s)  within the distribution system.  Sys-
   tems using  water contaminated with effluent
   from nuclear facilities: No reduced monitoring
   is allowed.
  Vulnerable  systems only (as designated by
   State): Since only vulnerable systems are
   required to monitor, no reduced monitoring
   is allowed.
 Vulnerable systems  only (as designated by
   the State): Since only vulnerable systems
   are required to monitor,  no reduced moni-
   toring is allowed.
 15. Laboratory Capacity Issue " Possible
 Extension of Initial Monitoring Period
  As discussed earlier in the analytical
 methods section (III.J), the Performance
 Evaluation Program (now known as the
 Proficiency Testing Program) has been
 externalized. Although the Agency is
 unsure at this time how externalization
 may affect laboratory capacity, EPA
 recognizes that it may be an
 implementation issue for at least three
 reasons:
  • The recent externalization of the
 radionuclides Performance Evaluation
 (PE) studies program may cause short-
 term disruption in laboratory
 accreditation;
  • Requiring NTNCWSs to monitor
 under the Standard Monitoring
Framework will add approximately
 20,000 systems to the universe of
systems that are already required to
monitor;
  • And the radon rule will be
implemented simultaneously with the
radionuclides rule.
  NIST is in the process of approving a
provider for PT samples for
radionuclides. States also have the
option of approving their own PT
sample providers. Should laboratory
capacity issues related to externalization
 present implementation problems for
 the initial monitoring period (three
 years), EPA will consider allowing an
 additional year (four years total) for the
 initial monitoring period. During the
 specified time period, systems would be
 required to analyze four consecutive
 quarterly samples to determine
 compliance. If the final rule is
 promulgated in November of 2QOO, the
 new monitoring requirements would
 begin to be enforced in November of
 2003. If EPA implements a one year
 extension, water systems would have
 until December 31 of 2007 to complete
 the required initial monitoring. This
 scenario would allow the "one third of
 systems per year" strategy inherent in
 the Standard Monitoring Framework to
 be applied, while allowing one
 additional year, if necessary, to address
 any laboratory capacity issues. EPA
 solicits public comment on this matter.
 L. Effective Dates
  Much of the rule that will be finalized
 in November will involve retaining
 current elements of the radionuclides
NPDWR. Those portions of the final rule
that are unaffected by the upcoming
regulatory changes are already in effect.
MCLs for gross alpha, beta particle and
photon radioactivity, and combined
 radium-226 and -228 will be unchanged
 and are already in effect. Regarding
 water systems that are currently out of
 compliance with the existing NPDWRs
 for gross alpha, combined radium-226
 and -228, and/or beta particle and
 photon radioactivity, States with
 primacy and EPA will renegotiate
 enforcement actions that put systems on
 compliance schedules as expeditiously
 a_s possible.
  Under the Safe Drinking Water Act,
 final rules become effective three years
 after promulgation (November of 2003,
 assuming that the rule becomes final in
 November of 2000}. The following
 discussion assumes a promulgation date
 of November 2000. For reasons
 described in the monitoring section of
 the NODA (section III, part K) and the
 Appendices (appendix V), initial
 monitoring will be required to
 completed by December 31, 2007. Under
 the Standard Monitoring Framework,
 systems have three years to complete
the initial monitoring cycle of four
 consecutive quarterly samples,
However, for reasons described in the
monitoring section of the NODA
 (section III, part K) , systems will have
an additional year to complete the
initial monitoring cycle, which will
correspond to an end date of December

-------
21598
Federal Register/Vol.  65,  No. 78/Friday,  April 21,  2000/Proposed Rules
31, 2007. This includes initial
monitoring for uranium, the new
monitoring requirements for radium-
228, and new initial monitoring under
the requirements for entry points.
Compliance determinations and future
monitoring cycle schedules are also
discussed in the monitoring sections
cited. MCL violations resulting from the
new requirement for separate Ra-228
monitoring will be treated as "new
violations" and will be on the same
schedule as other new violations (e.g.
uranium).
M, Costs and Benefits
  The Safe Drinking Water Act provides
for EPA to consider both public health
and the feasibility (taking costs into
consideration) in establishing drinking
water MCLs. In addition the new
Amendments require EPA to evaluate
the costs and benefits of potential
revisions to the current standards. As
noted earlier, the Agency conducted an
analysis of the costs and associated
benefits of each of the options described
in today's document. These analyses
were performed consistent with the
requirements for a Health Risk
Reduction and Cost Analysis set forth in
the 1906 Amendments to the SDWA
(section 1412(b)(3)(C)).
  First, all public water systems that are
currently treating and are in compliance
with the 1976 standards will have no
additional cost if the rule remains the
same as it is now. At the same time, EPA
recognizes that it may be costly to
systems which have delayed
compliance. However, to the extent the
rule remains the same, costs necessary
to comply with the existing rule, as well
as public health benefits associated with
it, have accrued to that 1976 rule. If EPA
changes nothing, the existing 1976
requirements must be met. EPA
considers only those costs associated
with accommodating revisions to the
current regulations to be new costs.
Costs incurred, or those that should
have been incurred to comply with a
previous regulation, are not factored
into current considerations.
  Second, EPA has reexamined the
costs of the 1991 proposal regarding
monitoring for any changes which may
be warranted based on new data. EPA is
contemplating several changes which
were part of the 1991  proposed
regulation and which may increase
costs. These include: (1) Promulgating
an NPDWR for uranium; (2) applying
the radionuclide NPDWRs to non-
transient, non-community  (NTNC)
systems; (3) requiring monitoring at the
point of entry to distribution systems,
and ; (4) requiring separate monitoring
for radium-226 and radium-228.
                     l_r.L UAt^ JLt-¥ J.^A'JJ.J. IW LJJ
                     The Agency will pt
                     timely analysis of g
  EPA is also recommending rapid
sample analysis for alpha emitters to
detect the presence of short lived
radionuclides such as radium-224, but
is not contemplating requiring it as part
of the revision to the radionuclides rule.
                pursue the issue of a
                ; gross alpha to reflect
short half lived Ra-224 in a separate
proposal.
  Costs and benefits for the various
options are presented in appendix V of
today's document, in the Technical
Support Document (EPA 2000a), and in
the draft Health Risk Reduction and
Cost Analysis (EPA 2000b). Today's
NODA solicits comment on whether the
incremental risk reduction may justify
the costs for certain of the revisions
described in the NODA. EPA requests
public comment on such questions and
on the extent to which its discretionary
authority provided by section 1412(b)(6)
of the SDWA should be used. This
NODA also requests public input
regarding the need for further
adjustments to the limits based on the •
cost and risk data presented in today's
NODA.

IV. References

  Parsa, Bahman. "Contribution  of Short-
Lived Radionuclides to Alpha-Particle
Radioactivity in Drinking Water and Their
Impact on the Safe Drinking Water Act
Regulations". Radioactivity &
Radiochemistry (Vol. 9, No. 4). pp. 41-50).
1998.
  USEPA. Drinking Water Regulations;
Radionuclides. Federal Register, Vol. 41, No.
133, p. 28402. July 9,1976.
  USEPA. National Primary Drinking Water
Regulations; Radionuclides; Proposed Rule.
Federal Register, Vol. 56, No. 138, p. 33050.
July 18,1991.
  USEPA. Presumptive Response Strategy
and Ex-Situ Treatment Technologies for
Contaminated Ground Water at CERCLA
Sites: Final Guidance. EPA 540/R-96/023.
(EPA 1996a)
  USEPA. Performance Evaluation Studies
Supporting Administration of the Clean
Water Act and the Safe Drinking Water Act.
Federal Register, Vol. 61, No. 139,  p. 37464.
July 18,1996. (EPA 1996b)
  USEPA. National Primary Drinking Water
Regulations; Analytical Methods for
Radionuclides; Final Rule and Proposed
Rule. Federal Register, Vol. 62, No. 43, p.
10168. March 5,1997. (EPA 1997a)
  USEPA. Performance Evaluation Studies
Supporting Administration of the Clean
Water Act and the Safe Drinking Water Act.
Federal Register, Vol. 62, No. 113,  p. 32112.
June 12,1997. (EPA 1997b)
  USEPA. Performance Based Measurement
System. Federal Register, Vol. 62, No. 193,
p. 52098.  October 6,1997. (EPA 1997c)
  USEPA. Manual for the Certification of
Laboratories Analyzing Drinking Water. EPA
815-B-97-001.1997. (EPA 1997d)
  USEPA. 1997. Memorandum from
Administrator Carol  M. Browner of EPA to
 Chairperson Shirley A. Jackson of the
 Nuclear Regulatory Commission. February 7,
 1997. (EPA 1997e)
   USEPA. Office of Solid Waste and
 Emergency Response (OSWER). 1997.
 Memorandum from Stephen Ludwig and
 Larry Weinstock (Office of Radiation and
 Indoor Air) to Addressees. "Establishment of
 Cleanup Levels for CERCLA Sites with
 Radioactive Contamination". OSWER No.
 9200.4-18. August 22,1997. (EPA/OSWER
 1997a).
   USEPA. Office of Solid Waste and
 Emergency Response (OSWER). 1997.
 Memorandum from Timothy Fields to
 Regional Administrators. "The Role of
 CSGWPP's in EPA Remediation Programs".
 OSWER No. 9283.1-09. April 4,1997. (EPA/
 OSWER 1997b).
   USEPA. Memorandum to Water
 Management Division Directors, Regions I-X,
 from Cynthia C. Dougherty, Director, Office
 of Ground Water and Drinking Water
 regarding Recommendations Concerning
 Testing for Gross Alpha Emitters in
 DrinkingWater (January 27,1999). (EPA
 1999a)
   USEPA. Cancer Risk Coefficients for
 Environmental Exposure to Radionuclides,
 Federal Guidance Report No. 13. US
 Environmental Protection Agency,
 Washington, DC, 1999. (EPA 1999b)
   USEPA. "Technical Support Document for
 the Radionuclides Notice of Data
 Availability". Draft. March, 2000. (EPA
 2000a)
   USEPA. "Preliminary Health Risk
 Reduction and Cost Analysis: Revised
 National Primary Drinking Water Standards
 for Radionuclides". Prepared by Industrial
 Economics, Inc. for EPA. Draft. January 2000.
 (EPA 2000b)
   U.S. Environmental Protection Agency.
 Memorandum to David Huber, Edwin
 Thomas, OGWDW from Scott Telofski, ORIA
 regarding Uranium Analysis Screening Level
 for Drinking Water Regulations NODA.
 March 14, 2000. (EPA 2000c)
   U.S. Environmental Protection Agency.
 Memorandum to David Huber, Edwin
 Thomas, OGWDW from Scott Telofski, ORIA
 regarding Gross Alpha Screening for
 Uranium. March 20, 2000. (EPA 2000d)
   U.S. Geological Survey (USGS). "Radium-
 226 and Radium-228 in a Shallow Ground
 Water, Southern New Jersey". Fact Sheet FS-
 062-98. June 1998.

 Appendix I—Occurrence
   In order to estimate the total national costs
 and benefits of revising the MCLs it is
 necessary to develop updated national
 estimates of the occurrence and exposure to
 these radionuclide contaminants in drinking
 water. Occurrence data and associated
 analyses provide indications of the number
 of public water supply systems with
 concentration of radionuclides above the
 revised MCL as well as the population served
. by these systems. Monitoring and treatment
 costs can be estimated from the occurrence
 data.

 A. Background
   EPA conducted a nationwide occurrence
 study of naturally occurring radionuclides in

-------
                      Federal Register/Vol.  65, No. 78/Friday, April  21, 2000/Proposed Rules
                                                                            21599
 public water supplies called the National
 Inorganic and Radionuclides Survey (NIRS)
 (see EPA 1991, proposed rule). The objective
 of NIRS was to characterize the occurrence of
 a variety of constituents, including radium-
 226, radium-228, uranium (mass analysis),
 gross alpha-particle activity, and gross beta-
 particle activity, present in community
 ground-water supplies (finished water) in the
 United States, and its territories. The survey
 included a random sample from 990
 collection sites. The public water supplies
 were stratified into four size categories, and
 the samples were chosen to best represent the
 same stratification present in the total
 population of community water supply in
 existence at the time, as shown in
 	Table 1-1.
    TABLE 1-1 .—COMPARISON OF NIRS TARGET SAMPLE WITH FEDERAL REPORTING DATA SYSTEM (FRDS) INVENTORY
Population category (population range)
Very small (25-500) 	
Small (501-3,300) 	 	 	
Medium (3,301-10,000) 	
Large and very large (10,001->100,000) 	

Total 	
Number of
FRDS sites*
34 040
10 155
2 278
1 227

47,700
Percentage of
FRDS sites
71 4
21 3
48-
2 6

100.1
Number of
NIRS sites
71 fi
91 1

OR

1,000
Percentage of
NIRS sites





100.0
   "Based in FRDS inventory for fiscal year 1985 from Longtin, 1988.
   Results of NIRS were used to develop the
 proposed radionuclide rule in 1991 (56 FR
 33050; EPA 1991). There has not been a
 comparable national survey for radionuclides
 since. Since the publication of the proposed
 1991 revision to the MCLs, the United States
 Geological Survey has collected additional
 data on various radionuclides in groundwater
 to augment the data of the NIRS. These
 studies are summarized subsequently, and in
 greater detail in the Technical Support
 Document (EPA 2000a).
   Szabo and Zapecza (1991) detail the
 differences in the occurrence of uranium and
 radium-226 in oxygen-rich and oxygen-poor
 areas of aquifers. Because the chemical
 behavior of uranium and radium are vastly
 different, the degree of mobilization of the
 parent and product are different in most
 chemical environments.
   Recently, high concentrations of radium
 were found to be associated with ground
 water that was geochemically affected by
 agricultural practices in the recharge areas by
 strongly enriching the water with competing
 ions such as hydrogen, calcium, and
 magnesium (Szabo and dePaul, 1998).
 Radium-228 was detected in about equivalent
 concentrations as radium-226 in the aquifer
 study in New Jersey (Szabo and dePaul,
 1998).

 B. USGS Radium Survey
  A 1998 USGS survey (see EPA 2000a) was
 designed to target areas of known, or
 suspected, high concentrations of radium-224
 as inferred by associated radium occurrence
 data, geologic maps, and other geochemical
 considerations. Thus, the survey is likely
 biased toward the extreme high end of the
 occurrence distribution for radium-224 and
 co-occurring contaminants such as radium-
 228. Approximately half of the samples were
 below the minimum detectable concentration
 of radium-226 and radium-228 in spite of the
 fact that public water systems were targeted
 in areas where high concentrations of radium
 were expected. Table 1-2 shows that, of the
 104 samples, 21 exceeded the MCL for
 combined radium, and about 5 percent
 exceeded 10 pCi/L of radium-224, though
 several  of these samples with pH less than
 4.0 also contained detectable concentrations
 of thorium isotopes as well. Concentrations
 exceeded 1 pCi/L in about 10 percent of the
 samples analyzed for lead-210 and 3 percent
 for polonium-210.
                        TABLE 1-2.—PERCENT OF SAMPLES EXCEEDING SPECIFIED CONCENTRATION
Radionuclide
Ra-224 	 	 	
Ra-226 	 	 	 	 	 	 	
Po-210 	
Pb-210 	

Total num-
ber of sam-
ples
104
104
95
96
Percent of samples exceeding given concentration (pCi/L)
1
30
33
3
10
2
26
22
1
3
3
20
17
1
1
5
15
10
1
1
7
9
5
0
0
10
5
2
0
0
  Radium-224 occurs in many of the wells
sampled at concentrations that highlight the
limitations of the present monitoring scheme
for the gross alpha-particle standard. In
addition, the contribution of radium-224 and
its short-lived daughter products to gross
alpha emissions was estimated with data
from a concurrent study of ground-water
supplies by the USGS in cooperation with
the state of New Jersey (Szabo et al., 1998).
In that study, gross alpha emissions were
measured before the decay of radium-224 and
after sufficient time had elapsed for radium-
224 decay (about 18-22 days). In this way,
the difference between the initial gross-alpha
measurement and the final measurement is
indicative of the contribution of radium-224
and all other alpha emitting isotopes that
would decay within this time frame. The
results indicate that the contribution of
radium-224 and its short-lived daughter
products is approximately three times the
concentration of radium-224. While this
analysis was developed with a small data set
in a restricted geographic range, it is based
on a physical process and has important
implications for such things as projections of
radium-224 occurrence in association with
gross-alpha concentrations. These results are
also important in light  of both the costliness
and difficulty of the radium-224 analysis.
  Concentrations of radium-228 were highly
correlated with radium-224. Although this
correlation was based on a limited number of
data points, there is a physical basis to the
correlation since both nuclides originate from
the same decay chain. Therefore, there is
potential for using radium-228 as a proxy
indicator for the much  shorter lived and
infrequently sampled radium-224. In
addition, the isotopic ratios of radium-226 to
radium-228 were below 3:2 in many samples
indicating that the gross alpha-particle screen
that is currently used for combined radium
(radium-226 + radium-228) compliance
would be Inadequate in many situations.
  Polonium-210 and lead-210 are derived
from the uranium-238 decay series; the decay
series that produces radium-226; However,
the survey was designed to assess radium-
224; therefore results are possibly biased to
areas that would more likely have isotopes in
the thorium-232 decay series. In addition, the
correlations of radium-226 with radium-224
and radium-228 are only 0.51 and 0.61
respectively; consequently, the wells that
were sampled may not be located in areas
expected to have polonium-210 or lead-210.
Within these constraints, the new data help
to fill the gap in occurrence information that
existed for these isotopes. Polonium-210 was
found in concentrations exceeding 1 pCi/L in
only two wells. At this time, these

-------
21600
Federal  Register /Vol. 65, No.  78/Friday, April  21, 2000 / Proposed  Rules
observations could not be associated with
unique geochemical controls (as has been
accomplished in a previous study in Florida;
Harada et al., 1989) and further investigations
would be necessary to infer anything more
about the national distribution and
occurrence of polonium-210.
  Approximately 12 percent of the samples
exceeded a lead-210 concentration of 1 pCi/
L; however only one sample was greater than
3 pCi/L. The greatest frequency of detection
was in the Appalachian Physiographic
Province of the northeastern United States,
especially in of Connecticut and
Pennsylvania. The geochemical mechanism
that controls lead-210 dissolution is also not
well established and needs further study,
though lead is less soluble than radium. In
addition, lead-210. like polonium-210, is
derived from a different decay chain than
radlum-224 and it was therefore not
considered in designing the study. One
possible explanation for the frequent
detection of lead-210 in concentrations
greater than 1 pCi/L in the Appalachian
region may be the high concentrations of
radon-222 in ground water in this region
(Zapecza and Szabo, 1986). As the radon in
solution decays through a series of very short
half-lived products to Lead-210, a small
fraction of the lead-210 may not be sorbed
onto the aquifer matrix; thus, the higher the
initial radon-222 concentration, the more
likely measurable amounts of lead-210 would
be found in the ground water. This
hypothesis could not be tested however
because radon-222 was not analyzed in this
study.
C.  USCS Beta/Photon Data Collection Effort
   The major source of data for man-made
radionuclides is the Environmental Radiation
Ambient Monitoring System (ERAMS) which
is published quarterly in the Environmental
Radiation Data (ERD) reports. The ERD
reports provide concentration data on gross
beta-particle activity, tritium, strontium-90,
and iodine-131 for 78 surface-water sites that
are either near major population centers or
near selected nuclear facility environs.
   An additional data collection effort was
 completed by the U.S. Geological Survey  in
 the summer of 1999 (see EPA 2000a) to
 analyze targeted beta-particle emitting
 radionuclides from a small number of public
 water systems that had shown relatively high
 levels of beta/photon emitters during the
 original N1RS survey. Of the 26 public water
 systems contacted for this effort none could
 ascertain which wells in their systems were
 originally sampled as part of NIRS.
 Consequently, although all efforts were made
 to include as many of the original systems as
 possible, it is presently unknown if the wells
 sampled match those in NIRS. The
 radionuclide analyses for this data collection
 effort included; short-term (48 hour) gross
 beta-particle and gross alpha-particle
 activities, long-term (30 days) gross beta-
 particle and gross alpha-particle activities,
 tritium, strontium-89, strontium-90, cesium-
 134, cesium-137, iodine-131, uranium-234,
 uranium-235, uranium-238, radium-228,
 radium-226, lead-210, and cobalt-60.
    Gross beta-particle activities were all below
 50 pCl/L in water collected from public water
                      systems that were sampled previously during
                      the National Inorganics and Radionuclide
                      Survey (NIRS) and had been found to contain
                      gross beta-particle activity in excess of 20
                      pCi/L. To the extent possible, all samples
                      were collected from the original public water
                      systems surveyed for NIRS where gross beta-
                      particle activities were 20 pCi/L or greater.
                      However due to the amount of time that had
                      elapsed since the NIRS samples were
                      collected, correlation with the original
                      sampling point could not be verified for
                      every water supply sampled.
                        Though the number of samples was limited
                      (26 samples), a few conclusions can be
                      reached. Concentrations of gross beta-particle
                      activities will rarely exceed 50 pCi/L in water
                      collected from public water systems (and did
                      not do so in this study). A significant
                      percentage (15% or 4 samples) of the 26
                      samples analyzed, however, contained gross
                      alpha-particle activities at or in excess of the
                      15 pCi/L MCL indicating that concern over
                      the presence of elevated concentration of
                      gross alpha-particle activity in ground water
                      is justified. Long-term (30-day) gross beta-
                      particle activity analyses did not indicate
                      significant ingrowth of beta-particles in any
                       of the samples, though this result is qualified
                      by the absence of significant quantities of
                       uranium-238 in any of the samples collected.
                       Naturally occurring potassium-40 and
                       radium-228 are a significant source of gross
                       beta-particle activity to many of the samples
                       in agreement with results of Welch et al.,
                       1995., Minor concentrations of naturally-
                       occurring lead-210 are also detected
                       occasionally. No manmade radionuclide was
                       detected in concentration above the
                       maximum detectible concentration (MDC) in
                       any of the samples. The presence of naturally
                       occurring beta-particle emitting
                       radionuclides must be taken into account
                       when evaluating the source of high gross
                       beta-particle activity in ground water as first
                       suggested by Welch et al., 1995.

                       D. References
                         Harada, Kow, William C. Burnett, Paul A.
                       LaRock, and James B. Cowart, 1989.
                       Polonium in Florida groundwater and its
                       possible relationship to the sulfur cycle and
                       bacteria. Geochemical et Cosmochimica Acta
                       Vol. 53, pp. 143-150.
                         Longtin, Jon, 1988. Occurrence of Radon,
                       Radium and Uranium in Groundwater.
                       Journal American Water Works Association,
                       pp. 84-93.
                         Szabo, Z., and V.T dePaul, 1998. Radium-
                       228 and radium-228 in shallow ground
                       water, southern New Jersey. U.S. Geological
                       Survey Fact Sheet FS-062-98.
                         Szabo, Z., V.T. dePaul, and B. Parsa, 1998.
                       Decrease in gross alpha-particle activity in
                       water samples with time after collection from
                       the Kirkwood Cohansy aquifer system in
                       southern New Jersey: Implications for
                       regulations. Drinking Water 63rd annual
                       meeting American Water Works Association
                       New Jersey Section. Atlantic City, NJ.
                         Szabo, Z., and O.S. Zapecza, 1991,
                       Geologic and geochemical factors controlling
                       uranium, radium-226, and radon-222 in
                       ground water, Newark Basin, New Jersey:
                       Gundersen, L.C.S. and Wanty, R.B., eds..
                       Field studies of radon in rocks, soils, and
water, U.S. Geological Survey Bulleting 1971,
p. 243-266.
  USEPA. National Primary Drinking Water
Regulations; Radionuclides; Proposed Rule.
Federal Register. Vol. 56, No. 138, p. 33050.
July 18,1991.
  USEPA. "Technical Support Document for
the Radionuclides Notice of Data
Availability". Draft. March, 2000. (EPA
2000a)
  Welch, A.H., Szabo, Z., Parkhurst, D.L.,
Van Meter. P.C., and Mullin, A.H., 1995,
Gross-beta activity in ground water: natural
sources and artifacts of sampling and
laboratory analysis: Applied Geochemistry, v.
10, no. 5, p.  491-504.
  Zapecza, O. S., and Z. Szabo, 1986. Natural
radioactivity in ground water—a review. U.S.
Geological Survey National Water Summary
1986, Ground-Water Quality: Hydrologic
Conditions and Events, U.S. Geological
Survey Water Supply Paper 2325. pp. 50-57.

Appendix II—Health Effects
  The following information summarizes the
salient changes in risk assessment
information and risk characterization
methodology during the past two decades.
The Technical Support Document (EPA
2000a) also  provides additional information.

A.  Use of Linear Non-Threshold Assumption
  In estimating the health effects from
radionuclides in drinking water, EPA
subscribes to the linear, non-threshold model
which assumes that any exposure to ionizing
radiation has a potential to produce
deleterious  effects on human health, and that
the magnitude of the effects are directly
proportional to the exposure level. The
Agency further believes that the extent of
such harm can be estimated by extrapolating
effects on human health that have been
 observed at higher  doses and dose rates to
those likely to be encountered from
environmental sources of radiation. The risks
 associated with radiation exposure are
 extrapolated from a large base of human data.
 EPA recognizes the inherent uncertainties
 that exist in estimating health impact at the
 low levels of exposure and exposure rates
 expected to be present in the environment.
:EPA also recognizes that, at these levels, the
 actual health impact from ingested
 radionuclides will  be difficult, if not
 impossible, to distinguish from natural
 disease incidences, even using very large
 epidemiological studies employing
 sophisticated statistical analyses. However,
 in the absence of other data, the Agency
 continues to support the use of the linear,
 non-threshold model in assessing risks
' associated with all carcinogens.

 B. Continuous Improvements in Models, Data
 Base
    As various scientific institutions have
 continued to collect data on the observed
 effects of radiation from the cohort of bomb
 survivors, patients with medical exposure,
 and workers with occupational exposure;
 continuous improvements have been possible
  in models to extrapolate effects and to
  estimate the risks of small exposures to
  radiation from the natural environment or
  man-made sources. The data have led to

-------
                      Federal Register/Vol.  65, No. 78/Friday, April 21, 2000/Proposed Rules
                                                                            21601
 changes in risk estimates as summarized
 here.
 1. Basis of 1976 Estimates of Risk
   • Risk of bone cancer from radium dial
 painters.
   • Autopsy radioassay (see EPA 2000a).
 Body burden from natural intake or radium,
 about 1 pCi/day.
   • Estimate annual dose rate in several
 organs from natural radium in rad/year.
   • BEIRI risk numbers for radium dial
 painters yields risk/year per rad/year.
   • Calculate risk over lifetime.
   a. 1976 Estimates of the Risks from
 Radium-226 and Radium-228. In general,
 EPA followed the Federal Radiation Council
 (FRC) recommendation that radium ingestion
 limits for the general population should be
 based on environmental studies and not the
 models used to establish occupational dose
 limits (see EPA 2000a). In setting the MCL,
 EPA considered bone cancer and other soft
 tissue cancers to be the principal health
 effects associated with radium ingestion. To
 calculate body burdens, doses, and risks from
 ingestion of radium-226 and radium-228, in
 1976, EPA relied on data from the 1972
 report of the United Nations Scientific
 Committee on the Effects of Atomic
 Radiation (see EPA 2000a) and the 1972 the
 National Academy of Sciences (NAS)
 Committee on the Biological Effects of
 Ionizing Radiation, BEIR I Report (see EPA
 1991, proposed rule). Additional information
 and support were found in the International
 Commission on Radiological Protection,
 Publication 20 (see EPA 2000a). The
 literature suggests that radium-228 was as
 toxic as radium-226, and possibly twice as
 toxic for bone cancers in dogs. Given this,
 EPA believed that it was prudent to assume
 that the adverse health effects due to
 chronically ingested radium-228 were at least
 as great as those from radium-226.
  Assuming equal toxicity with radium-226,
 EPA reasoned that lifetime ingestion of only
 radium-228 at 5 pCi/L would yield lifetime
 total cancer risks equal to those for a lifetime
 ingestion of only radium-226 at the same
 concentration, i.e., between 0.5 to 2 x 10 ~4.
 By setting the MCL at 5 pCi/L for radium-226
 and radium-228 combined, rather than
 individually, EPA sought to limit the lifetime
 total cancer risk from the ingestion of both
 isotopes in drinking water to 2 x 10 ~4 or less.
  b. Basis for the 1976 MCL for Gross Alpha
 Particle Activity. One of the main intentions
 of the 15 pCi/L MCL for gross alpha particle
 activity, which includes radium-226 but •
 excludes uranium and radon, was to limit the
 concentration of other naturally-occurring
 and man-made alpha emitters relative to
 radium-226. Specifically, this limit was
based on the fact that EPA estimated that
 continuous consumption of drinking water
 containing polonium-210, the next most
radiotoxic alpha particle emitter in the
radium-226 decay chain, at a concentration
 of 10 pCi/L might cause the total dose to
bone to be equivalent to less than 6 pCi/L of
radium-226.
  The 15 pCi/L limit, which includes
radium-226 but excludes uranium and radon,
was based on the conservative assumption
that if the radium concentration is limited to
5 pCi/L and the balance of the alpha particle
 activity (i.e., 10 pCi/L) is due to polonium-
 210, the total dose to bone would be less than
 that dose associated with an intake of 6 pCi/
 L of radium-226.
  c. Basis for the 1976 MCL for Beta Particle
 and Photon Radioactivity. In 1976, EPA
 estimated that continuous consumption of
 drinking water containing beta and photon
 emitting radioactivity yielding a 4 mrem/yr
 total body dose may cause an individual fatal
 cancer risk of 0.8 x 10~6 per year, or a
 lifetime cancer risk of 5.6 x 10~5, assuming
 a 70-year lifetime. In setting the MCL for
 man-made beta and photon emitters, EPA
 used cancer risk estimates from the BEIR I
 report for the U.S. population in the year
 1967 (see EPA 1991, proposed rule). For an
 exposed group having the same age
 distribution as the U.S. 1967 population, the
 BEIR 1 report indicated that the individual
 risk of a fatal cancer from a lifetime total
 body dose rate of 4 mrem per year ranged
 from about 0.4 to 2 x W~6 per year
 depending on whether an absolute or relative
 risk model was used. Using best estimates
 from both models for fatal cancer, EPA
 believed that an individual risk of 0.8 x 10 ~*
 per year resulting from  a 4 mrem annual total
 body dose was a reasonable estimate of the
 annual risk from a lifetime.ingestion of
 drinking water. Over a 70-year period, the
 corresponding lifetime fatal cancer risk
 would be 5.6 x 10 "5, with the risk from the
 ingestion of water containing less amounts of
 radioactivity being proportionately smaller.
  Based on 1967 U.S. Vital Statistics (see
 EPA 1991 and EPA 2000a), the probability
 that an individual would die of cancer was
 about 0.19, and was thought to be increased
 by 0.1 percent from a lifetime dose
 equivalent rate of 15 mrem per year.
 Therefore, EPA calculated that the 4 mrem/
 yr MCL for man-made beta and photon
 emitters corresponded to a lifetime risk
 increase of 0.025 percent to exposed groups.
  EPA knew that partial body irradiation was
 common for ingested radionuclides since
 they are, like radium, largely deposited  in a
 particular organ, or in a few organs. In such
 cases, EPA acknowledged that the risk per
 millirem varies depending on the
 radiosensitivity of the organs at risk. For
 example, EPA estimated that cancers due to
 the thyroid gland receiving 4 mrem per  year
 continuously ranged from about 0.2 to 0.5 per
 year per million exposed persons (averaged
 over all age groups). Considering the sum of
 the deposited fallout radioactivity and the
 additional amounts due to releases from
 other sources existing at that time, EPA
 believed that the total dose equivalent from
 man-made radioactivity was not likely to
 result in a total body or organ dose to any
 individual that exceeded 4 mrem/yr.
 Consequently, EPA did not believe that  the
 4 mrem/yr standard would affect many
 public water systems, if any. At the same
 time, the Agency believed that ah MCL set at
this level would provide adequate public
health protection.
 2.1991 Proposal: Basis of Health Risk
Estimates
  During the years since the  publication of
the 1976 regulations, the Agency obtained a
great deal of additional data and a better
understanding of the risks posed to human
 health by ingested radionuclides. Many of
 these new studies were presented and
 discussed in the Advance Notice of Proposed
 Rulemaking announcing EPA's intent to
 revise the MCLs (51 FR 34836, Sept. 20,
 1986) and the supporting health criteria
 documents (see EPA 2000a and EPA 1991,
 the proposed rule).
   Among the most important changes made
 by EPA in developing the 1991 revisions was
 the adoption of a common calculational
 framework, the RADRISK computer code (see
 EPA 1991, proposed rule), to estimate the
 risks posed by ingestion of radionuclides in
 drinking water. The RADRISK code consisted
 of intake, metabolic, dosimetric, and risk
 models that integrated the results of a large
 number of studies on a variety of radioactive
 compounds and radiation exposure
 situations into an overall model to estimate
 risks for many different radionuclides.
 Radionuclide-specific parameters were based
 on the results of individual scientific studies
 of a specific radionuclide, such as radium;
 human epidemiological studies; or
 experimental animal studies of groups of
 chemically-similar radionuclides. To
 summarize, the following are some of the
 salient changes.
   • Used RADRISK metabolic model instead
 of natural uptake equilibrium model. Based
 on known intakes.
   • Used ICRP report 20 (see EPA 2000a) on
 alkaline earth elements with Oak Ridge
 modeled exponential fit to that model.
   • BEIR IV risks for alpha emitters.
   • Ra-224 data from ankylosing
 spondylitis, tuberculosis.
   • Change in results from Ra-228
 calculations (Oak Ridge model of '84) and
 ICRP 30 (see EPA 2000a) yielded different
 results based on retention and distribution of
 each member of decay chain.
   a. Basis for the 1991 MCL for Radium-226
 and Radium-228. In 1991, EPA proposed
 revised MCLs for radium-226 and radium-
 228 individually at 20 pCi/L each. The
 Agency thought at that time that the limit for
 each of these radium isotopes was within the
 Agency's acceptable risk range of 10 ~6 to
 10"*- The Agency no longer believes the
 MCLs proposed in 1991 for radium-226 and
 radium-228 are within the Agency's
 acceptable risk range.
  i. Human and Animal Health Effects Data
 Considered. In 1991, EPA based its risk
 estimates for radium using information from
 two epidemiological study groups. The first
 group consisted of radium dial painters who
 had ingested considerable amounts of radium
 paint (containing various proportions of
 radium-226 and radium-228) by sharpening
 the point of their paint brush with the lips.
The second group consisted of patients  in
Europe injected with a short-lived isotope of
radium, radium-224, for treatment of spinal
arthritis and tuberculous infection of the
bone (see EPA 2000a). The results of these
studies are described briefly next.
  At high levels of exposure to radium,
several non-cancer health effects were
observed in radium dial painters, such as
benign bone growths, osteoporosis, severe
growth retardation, tooth breakage, kidney
disease, liver disease, tissue necrosis,
cataracts, anemia, immunological
suppression and death (see EPA 2000a).

-------
21602
Federal Register/Vol.  65, No. 78/Friday, April 21, 2000/Proposed Rules
  Exposed radium dial painters also
exhibited significantly elevated rates of two
rare types ofcancer, bone sarcomas
(osteosarcomas, fibrosarcomas and
chondrosarcomas) and carcinomas of head
sinuses and mastoids (see EPA 2000a and
EPA 1991, the proposed rule). The incidence
of head carcinomas was associated with
exposure to radium-226, but not radium-228
(sec EPA 2000a). This is because these latter
oncers were due to an accumulation of
radon gas (radon-222) in the mastoid air cells
and paranasal sinuses caused by the escape
of radon-222 into the air spaces.
  ii. Body Burden, Dose, and Risk
Calculations. Risk calculations for ingested
                      radium were made using RADRISK (see EPA
                      1991, proposed rule) based on annual dose
                      rates. For this purpose, EPA computed dose
                      rates for specific organs and tissues at
                      specific ages for an annual unit intake of each
                      radium isotope (see EPA ZOOOa). Calculation
                      of body burdens was based on metabolic
                      models derived from the radium dial painter
                      studies. Calculations of absorbed doses in
                      specific organs or tissues included cross
                      irradiation from radium in all other organs.
                      RADRISK included lifetime cancer risk
                      estimates for high- and low-LET  (linear
                      energy transfer) radiation separately for
                      leukemia, osteosarcomas, sinus tumors, and
                      other solid tumors. These estimates were
taken from the BEIR III and BEIRIV (see EPA
1991, proposed rule) reports.
  Table II—1 compares the methods used by
EPA in 1976 and 1991 to calculate organ
burdens, doses, and risks from radium
ingestion. Bone doses calculated for radium-
226 in 1991 were about 33 percent lower
than those assumed in 1976, and the soft
tissue doses were about 40 percent lower.
Risk estimates for bone per unit dose were
about 65 percent lower in 1991 than in 1976,
and the soft tissue risk estimates were about
9 percent lower.
                     TABLE II-1.—COMPARISON OF DERIVATION OF 1976 AND 1991  MCLs FOR RADIUM
                   Model
                                                              1976
                                                                                                       1991
Organ and Tissue Burdens


Doslmetry 	


Risk Coefficients	
                       Calculation of body burdens based on envi-
                        ronmental studies and ratio of intakes.

                       Calculation of absorbed dose based on organ
                        and tissue burden.

                       Risk estimated  using the  geometric mean  of
                        the absolute  and relative  risk  coefficients
                        from the 1972 BEIR I report.
Calculation  of  body  burdens  based  on
  toxicokinetic models derived from studies of
  patients injected with radium.
Calculation of absorbed dose based on organ
  or tissue burden and cross irradiation terms
  from all other organs,
Risk estimated  using the absolute risk coeffi-
  cient from the 1980 BEIR III report.
  o. Basis for the 1991 MCLfor Gross Alpha
Particle Activity. In 1991, EPA proposed to
retain the 15 pCi/L MCL for gross alpha
particle activity, but modify it by excluding
radium-226, as well as uranium and radon.
The exclusion of uranium and radon was
based on the fact that the Agency anticipated
setting separate NPDWRs for these
contaminants with the finalization of the
1991 proposal. The proposed exclusion of
Ra-226 was based on the 1991 risk estimate
which suggested that its unit risk was small
enough not to warrant regulation within
gross alpha. The 1991 limit was intended to
limit the lifetime cancer risk due to ingestion
of naturally-occurring and man-made alpha
particle emitters in drinking water to
between 10~* and 10~4, the Agency's target
risk range for carcinogens. Specifically, this
limit was based on the following
considerations:
  Using RADRISK modeling, EPA estimated
that continuous consumption of 15 pCi/L of
most alpha particle emitters in drinking
water at 2 L/day would pose a lifetime cancer
risk between 10-* and 10~4.
  EPA performed the risk assessment for the
alpha emitters using RADRISK (EPA 1991,
proposed rule). The model was used to
estimate radiation dose to organs, the dose
was used to calculate risk to organs, and the
risks to organs were summed to estimate
overall risk. EPA used RADRISK to calculate
concentrations of alpha emitters
corresponding to lifetime mortality and
incidence risks of 10 ~4, assuming ingestion
of two liters of drinking water daily, and
presented those values in appendix C of the
1991 proposed rule.
  In determining the risks from ingestion of
alpha emitters in drinking water, EPA was
particularly interested in polonium-210 and
isotopes of thorium and plutonium, because
these radionuclides had been observed in
                      water and may cause health effects at
                      relatively low concentrations.
                       However, the BEIR IV report concluded
                      that there was no direct measure of risk for
                      most polonium isotopes based on the human
                      data, and suggested several possible means of
                      estimating risk. EPA, as discussed, relied on
                      RADRISK in assessing polonium risk. The
                      model estimated that continuous ingestion of
                      two liters per day of drinking water
                      containing 14 pCi/L would pose a lifetime
                      fatal cancer risk of 1 x 10 ~4.
                       EPA also consulted the BEIR IV report for
                      available information on the adverse effects
                      of thorium. Epidemiological studies of
                      patients injected with Thorotrast, a contrast
                      agent consisting of ThOa and used in medical
                      radiology from the 1920s to 1955, showed
                      clear increases in liver cancer, as well as
                      possible increases in leukemia and other
                      cancers. However, the BEIR IV report
                      discussed the limitations of these data for
                      assessing the risk due to other forms of
                      thorium that might have different metabolic
                      behaviors and effects. Using RADRISK, EPA
                      estimated that, at a lifetime fatal cancer risk
                      level of 1 x 10 ~4, derived drinking water
                      concentrations for thorium isotopes ranged
                      from 50 to 125 pCi/L, and noted that thorium
                      concentrations in drinking water were
                      generally near one  pCi/L (EPA, 1991fl.
                       EPA relied on the BEIR IV report for
                      information on the health effects of
                      plutonium isotopes and other transuranic
                      radionuclides that were widely distributed in
                      the environment in very low concentrations
                      due to atmospheric testing of nuclear
                      weapons from 1945 to 1963. The BEIR IV
                      report concluded that plutonium exposures
                      caused clear increases in cancers of the bone,
                      liver, and lungs in animals, but not in
                      humans.  At that time, the limited available
                      epidemiological studies had not
                      demonstrated a clear association between
plutonium exposure and the development of
cancer in human exposure cases. The report
recommended that assessing the risks of
plutonium exposure should be based on
analogy with other radionuclides and high-
LET radiation exposure risks. Using
RADRISK, EPA estimated that, at a lifetime
fatal cancer risk level of 1 x 10 ~4, derived
drinking water concentrations for plutonium
isotopes ranged from about 7 to 68 pCi/L, and
noted that plutonium concentrations in
drinking water were generally less than 0.1
pCi/L(EPA, 1991f).
  c. Basis for the 1991 MCL for Beta Particle
and Photon Radioactivity, In 1991, EPA
proposed to alter the 4 mrem/yr MCL for beta
particle and photon radioactivity. The
Agency modified the standard by basing the
limit on the committed effective dose
equivalent (EDE). (An effective dose
equivalent approach adjusts the dose that an
individual organ may receive based on its
radiosensitivity. The less radiosensitive an
organ is, the greater the allowable radiation
dose.) The MCL was also modified to include
naturally-occurring beta/photon emitters.
The 1991 proposed standard was intended to
limit the lifetime cancer risk due to ingestion
of naturally-occurring and man-made beta
particle and photon emitters in drinking
water to between 10 ~6 and 10 ~4- the
Agency's target risk range for carcinogens.
  Using RADRISK modeling, EPA estimated
that continuous consumption of two  liters
per day of drinking water containing a
concentration of beta particle or photon
emitting radiation corresponding to 4 mrem
EDE/yr would pose a lifetime cancer risk of
about 10 -*.
  Comparison of the 1976 Regulation and
1991 Proposed Regulation. In 1976, EPA
based the MCL for beta particle and photon
emitters on a target dose rate of 4 mrem/yr.
The annual average activity concentration of

-------
                      Federal Register/Vol. 65, No. 78/Friday, April 21, 2000/Proposed Rules
                                                                             21603
 individual radionuclides and mixtures of
 radionuclides resulting in a 4 mrem/yr dose
 to the total body or any internal organ was
 then calculated. This "critical organ dose"
 radiation protection philosophy was based
 on the recommendations of JCRP Publication
 2 (see EPA 2000a).
  The Agency was aware that in 1976, when
 exposed to equal doses of radiation, different
 organs and tissues in the human will exhibit
 different cancer induction rates.
 Consequently, EPA knew that the lifetime
- cancer risks for individual radionuclides
 would vary widely (from near 10 ~ 7 to 5.6 x
 IQ-fbecause the same dose equivalent
 would be applied to different critical organs,
 resulting in different cancer risks. However,
 at that time, EPA did not have an accepted
 method for equalizing risks. In addition,
 since no dose could be greater than 4 mrem
 tp every organ, the associated risk was the
 ceiling for the risk of beta/photon emitters in
 drinking water.
  This was addressed in 1991 when EPA
 proposed to adopt the effective dose
 equivalent, or EDE, radiation protection
 philosophy recommended by ICRP (1977)
 (see EPA 1991, proposed rule). The effective
 dose equivalent normalizes radiation doses
 and effects on a whole body basis for
 regulation of occupational exposures. The
 EDE is computed as the sum of the weighted
 organ-specific dose equivalent values, using
 weighting factors specified by the ICRP
 (1977,1979; see EPA 1991, proposed rule).
 By changing to a limit of 4 mrem EDE/yr,
 EPA was able to derive activity
 concentrations for individual beta/photon
 emitters that corresponded to a more uniform
 level of risk. Using 4 mrem EDE and the
 metabolically-based dose calculations, the
 derived concentrations for most beta particle
 and photon emitters increased in 1991 as
 compared to the values calculated in 1976
 (shown in Table H-3). As a result of derived
 concentrations increasing in 1991, the
 corresponding risks increased as well. EPA
 estimated that, for most of these
 radionuclides, the corresponding lifetime
 fatal cancer risk would be 1 x 10 ~4, about
 twice as high as the risk level estimated in
 1976.
  d. Basis for the 1991 Proposed MCLfor
 Uranium. In 1991, EPA proposed an MCL of
 20 ug/L for uranium based on kidney toxicity
 and a corresponding limit of 30 pCi/L based
 on cancer risk. The MCLG was proposed at
 zero because of the carcinogenicity of
 uranium, and the MCL was proposed at the
 most sensitive endpoint, kidney toxicity. The
 MCL was based on kidney effects seen in the
 30 day study in rats (see EPA 1991, proposed
 rule).
  Using RADRISK modeling, EPA estimated
 that uranium in water posed a cancer risk of
 5.9 x 10"7 per picoCurie per liter, assuming
 continuous intake _of water of two liters per
 day. Concentrations in water of 1.7 pCi/L, 17
 pCi/L and 170 pCi/L corresponded to lifetime
 mortality risks of approximately 1 x 10 ~6,1
 x 10~5 and 1 x 10~4, respectively. A
 concentration of 30 pCi/L of uranium-238
 was thought to be equivalent to about 20
 micrograms/L, the level considered to be
 protective against kidney toxicity (the
 corresponding mortality was 5 x 10 ~5.
  In determining the MCL for uranium in
 1991, EPA proposed to regulate uranium  at
 a level that would be protective of both
 kidney toxicity, resulting from the element's
 chemical properties, and carcinogenic
 potential due to radioactivity. The
 carcinogenic effects of uranium were based
 on the effects of ionizing radiation generally,
 the similarity of uranium to isotopes of
 radium, and on the effects of high activity
 uranium.

 C. Today's Methodology for Assessing Risks
 From Radionuclides in Drinking Water
 1. Background
  Since 1991, EPA has refined the way in
 which it estimates potential adverse health
 effects associated with ingestion of
 radionuclides in drinking water. The
 Agency's new approach uses state-of-the-art
 methods, models and data that are based on
 more recent scientific knowledge. Compared
 with the approaches used in 1976 and 1991,
 the revised methodology includes several
 substantial refinements. Specifically, the  new
 risk-assessment methodology:
  • Accounts for age- and gender-specific
 water-consumption rates and radionuclide
 intakes, and for physiological and anatomical
 changes with age in quantifying costs and
 benefits;
  • Uses Blue Book (see EPA 2000a) for
 estimating radiogenic risk: ICRP dosimetry
 model, 1990 vital statistics instead of 1980;
  • Uses the most recent age-dependent
 biokinetic and dosimetric models
 recommended by the ICRP; Federal Guidance
 Report-13 dynamic input-output metabolic
 model;
  • Incorporates the latest information on
radiogenic human health effects summarized
by the National Academy of Sciences and
 other national and international radiation-
 protection advisory committees;
  • Includes updated life tables based on
 data from the National Center for Health
Statistics that are used to adjust radionuclide
risk estimates for competing causes of death;
and
  • Uses an improved computer program to
handle the complex calculations of radiation
doses and risks.
  Overall, EPA believes that these
refinements significantly strengthen the
scientific and technical bases for estimating
risks, and consequently, for deriving MCLs
for radionuclides. A brief overview of this
new methodology is summarized later in this
section. Interested individuals are referred to
two EPA publications Estimating Radiogenic
Cancer Risks (EPA, 1994) and Federal
Guidance Report No. 13 (EPA, 1999) for
detailed discussions on the revised risk
assessment methodology for radionuclides.
Electronic copies of both documents are
available for downloading at EPA's web site
(http://www.epa.gov/radiation/
rpdpubs.htm).
  Federal Guidance Report No. 13: (EPA,
1999) presents the current methods, models,
and calculational framework EPA uses to
estimate the lifetime excess risk of cancer
induction following intake or external
exposure to radionuclides in environmental
media. The report presents compilations of
risk coefficients that may be used to estimate
excess cancer morbidity (cancer incidence)
and mortality (fatal cancer) risks resulting
from exposure to radionuclides. through
various pathways.
  The risk coefficients for internal exposure
represent the incremental probability of
radiogenic cancer morbidity or mortality
occurring per unit of radioactivity inhaled or
ingested. For most radionuclides. Federal
Guidance Report No.  13 presents risk
coefficients for seven exposure pathways:
inhalation, ingestion of food, ingestion of tap
water, ingestion of milk, external exposure
from submersion in air, external exposure
from the ground surface, and external
exposure from soil contaminated to an
infinite depth. For some radionuclides,
however, only external exposure pathways
are considered; these include noble gases and
the short-lived decay products of
radionuclides addressed in the internal
exposure scenarios.
  a. Radium. EPA set the current MCL of 5
pCi/L for radium-226 and radium-228,
combined, based on limiting the lifetime
excess total cancer risk to between 5xlO~5
and 2x10-4. In 1991, EPA proposed separate,
and revised, MCLs for radium-226 and
radium-228 of 20 pCi/L for each. At that
time, EPA believed that the revised MCLs
corresponded to lifetime excess fatal cancer
risks of 1x10 ~4 each, or 2x10~4 combined,
assuming lifetime ingestion. The more
sophisticated model used today calculates a
risk for Ra-228 at 5 pCi/1 to be 2x10-", and
the risk for 5 pCi/1 of Ra-226 to be about
7.3x10 -5. Retaining a combined MCL at 5
pCi/L would produce the following risks
shown in Table II-2.
               TABLE 11-2.—MORTALITY RISK OF RADIUMS FOR CONCENTRATION COMBINATIONS AT THE MCL
Radium-226
pCi/L
0 	 	 	
1 	
2 	 	 	
3 	 	 	 	 .
4 	 	 	
Risk
0
1.5x10-5
2.9x10-*
4.4x10-5
5.8x10-5
Radium-228
pCi/L
5
4
3
2
1
Risk
2.0x10-4
1.6x10-4
1.2x10-"
8.1x10-5
4 1x1O-5
Ra-226 + Ra-228
pCi/L
5
5
5
5
5
Risk at 5 pCi/L
2.0x10-
1.8x10-
1.5x10-
1.3x1.0-
QQvin-

-------
21604
Federal  Register/Vol.  65, No.  78/Friday, April 21, 2000/Proposed  Rules
       TABLE 11-2.—MORTALITY RISK OF RADIUMS FOR CONCENTRATION COMBINATIONS AT THE MCL—Continued
Radium-226
pCi/L
5 	 , 	

Risk
7.3x10-5
Radium-228
pCi/L
o ,;
Risk
0
Ra-226 + Ra-228
pCi/L
,,,5'
Risk at 5 pCi/L
7.3x10-5
  b. Alpha Emitters. Both the current and
1991 proposed MCLs for alpha-emitting
radionudides permit up to 15 pCi/L of alpha
particle radioactivity in drinking water from
individual and multiple alpha emitters. EPA
established the current gross alpha MCL of 15
pCi/L (including radium-226 and excluding
radon and uranium) to account for the risk
from radium-226 at 5 pCi/L (the radium
regulatory limit) plus the risk from
polonium-210, which the Agency believed
was the next most radiotoxic element in the
uranium decay chain. The current risk
estimated (FGR-13) indicates that the unit
risk for Ra-226 is large enough to warrant its
Inclusion in gross alpha, as thought in 1976.
  In 1991, EPA thought that exposure to 10
pCi/L of polonium-210 posed a lifetime fatal
cancer risk comparable to that from
continuous lifetime ingestion of about 1 pCi/
                      L of radium-226, that is, between 0.5 and
                      2xlO~4. In 1991, EPA based the revised,
                      adjusted gross alpha MCL on revised dose
                      and risk calculations which indicated that
                      the 15 pCi/L limit posed a lifetime cancer
                      risk for most alpha emitters that fell within
                      EPA's acceptable risk range of between 10 ~6
                      and 10—l.
                       The current estimate of risk from
                      polonium-210 at 7.0 pCi/L is 1x10 -*• The
                      risk for radium-226 at 6.8 p/L is also IxlQ-".
                      When the current rule was written, 10 pCi/
                      L of polonium-210 was believed to be
                      equivalent to 1 pCi/L of radium-226;
                      however, the risks are now equivalent. Thus
                      polonium is ten times the risk it was thought
                      to be relative to radium-226. Retaining a 15
                      pCi/L standard including radium-226 ensures
                      that the risk of 15 pCi/L will not increase by
                      allowing greater polonium (up to 15 pCi/L)
in addition to the radium-226 in the radium
standard. As expected, a uniform picoCurie
limit results in widely differing risks (EPA
2000a).
  c. Beta/Photon Emitters. As discussed
elsewhere in this document, EPA is able to
calculate the risks from individual beta/
photon emitters using the FGR-13
methodology. It is now possible to calculate
a risk equivalent to the current picoCurie
limit for each beta/photon emitter.
Appropriate adjustments are then possible in
keeping with the original risk maximum of
5.6xlO-5. The derived concentration values
for the beta particle and photon emitters from
1976 rule and 1991 proposal in comparison
to today's newest risk model using 5.6xlO~s
mortality are found in Table II—3.
BILLING CODE- 6560-50-U

-------
       Federal Register/Vol.  65, No.  78/Friday, April 21,  2000/Proposed Rules
21605
•tS


 a
 o
•o
 a>




 o



 S
 o
-o
 en
0 «!
o> o

vo 55
a
£


Cfl
.itf
.—
eo
"3 «- " -
.1 >*
"S *>
o E
£3
cu «
1 *
w
.£2
ci
\o
"O c
a a >.
•s 5i
IP
VO 0 ^I
r> e «
2 °
'o
=1 J
"S o
4> O
•0 JS
1s

























s
4>
o

s
§





O
V^
en

|
o"
ts







p
•T*


























S

*£

§
5





°
o

^

1
^0









23

























g
*)
JC

o
0
04
gj









CJ










O





























§
K




















i

























2
«
r-.

o
o
<-i





S
0>
o
_!

O
CM"









6





























0
o
S
VO"



















0





























O
C^
O
s




















6

























o
o
\o

s
s





!
f*^
OO

O
O
0


0
m








^.
w
























.




o
r^
OO
"~"




















a.

























cp
u
o
cs
i






1
m

o\

o
CO










OJ
a.

























o
o
—

o
o
£i





s
f*^
CO

0
u-j








»
o
^
m
CO

























S
i
OO
o

so
HP*





o
OO
p^

o
o
r-










O

























S
t>
OO

o
ol





o
^~
OO

o
o
""*








«.
OO
en
0

























S
4)
P*-

O
O
m





1
o
•Q.

o
o









^
cs
T

























S
t>
Io

o
p^-
"™





r-
o
o\
OO

o










-3*
ea

























g
^
s

OO






1
CO
„.

«










<^-
at
O
1

2











c:
o

1
3

p»-
*i=
•*•
o
cS
o
4>
OO

s
OO






1
ON
«.

§
—









vo
o
CO

























o
i
-3-

O
cs





I
ON

0

§
oc~





U-l
O
C*J
m

o
o
^0









ll
u

-------
21606
Federal Register/Vol.  65, No. 78/Friday, April 21, 2000/Proposed Rules
ill
o
»&s
,~ C O

•§ ^ oM
o
If
CQ J>;

— c _§
§0 t3
a i
C **-" •"*
ol|
ll
SO c/3
£Z

£

1
.3
E >,

if
o £
es. S
s •=
0. «

.££


vo
r*
o>
^ eo 3!^
ill
CM
O
IS o
^ s
? 2
— • 3

•3 ^
z















o

—

m






8
o
t—
f



o
0V





*?
S















TT
O
u
o
—

o
o
OJ






o
o
0)
(N



0
o





<0
2















s
u
OO
—

O
s
tr\





0
i>
vo
Ov



0
o
en




•
"?
S















s
^
n

o
o\





u-l
o
t>
CO
>o



o
1





!S
s.















0
D
fS

CO






s
o
—
VI



CD
:s





n
£















CD
«n
—

o
OO
T*«





s
4>
0)
fO



§





K
o
i

o
<=


p
dc
o
C
r«
"i
•—
^
"i
>
o
9
K
— •

§
__»





S
tt>
OO
DO



O
CD
O_





OO
o
ff

0
CD
0


OO
Vi

o
T*
"i
-a
o
v\
.3
a
C3
S
«N

CD
0
^>





§
1>
—
•_>



CD
O




F
00
5















0
!2
^

OO






CD
O
c^t
v^



CD
O





CD
SO
O















o
K
<^j

o
CD
O
p^.





0
3>
K
r^l



cs
o





Sn
2















o
S
(M

O
Cv





S
o
o
—



o





so
z















0
g
-"

o
OO
OO





o

n
sO



O
o
r-i




^
SO
z















o
JQ
f-»

§
^





O
u
r—
_



CD




*
sO
3















9
S
—

S






S
o
n
^n



CD
O





sO
•5















0
JC
-^

0
CD
<*^1
sn




o
u
SO
«



CD
CD
CD
sO*




*
O
N















0
o
ts

o
*^





o
i
o
w



o




c
s
C
tsl















o
C
IN

O
s
p-












CJ





SO
c3















o
ai
—

o
CN
«.*





O
V
so
*>•



o




•fr
^!
33
O















S
2
OO

0
o
o
sO

"*



0
i
—
^-t



o
0
o
v
<















0
OV
tN

0
C
_M





8
«
ii
V— 1



§





iS
<















0
—
m

m
^^





8
U
-g-
VM



O
CD
cs





^
<















o
s
—

s






o
u
SO
•s^



§





jO
0















o
sc
-*

o
f^)





VO
o
a>
CO
t^



o
o





Cvl
0
CQ



















0
VC

T1"
















CO
g

-------
Federal Register/Vol.  65, No. 78/Friday, April 21, 2000/Proposed Rules
21607

_ "°

•S s i
5S —
o
Ifi
3 "= ° J
20-3
S"8 =
O g -E:
o
3
2J o^
3 ^

— O
V)  p
IIs
"o
*« o
— ws
—• ' 3

Is

























n-
5

oc


•«•
A
O

0
o







o
CG

























C

v>


vv
A
^

o
o
en







o

























•^T
f
oc

i






2







I
i

























oc

1






o







?
cr.

























a

CN






CJ







a

u-i
O
u
ON
t--


c





(1
r
a
4
C
OO
o

tt
o
00
p
5:
S

be


CO
i
r-i

1







3

C

CM
—


C
O











o

c.
<2
OO
0



:


t^»
i
vo

§







3




























3S


\O
i
VO

O







>


























i




VI

s
cs
00







>




























3


V*
A
O

o







-—


























s

5


Wi
a>
CO

0
N







S


























S

»n


w^
^
S

o







S.


























vc

^O


Vk
^
o

o
^







—


























K

2


«n
V
o

i







?




























oo r



o -
00 V
•^f CX

0 C
O O1







s s;


























3~ — a

- S 2-



J ? ?

- OO CN
> O O
* o o
o^ c*»







g %>


























£ 1 3 S 1

s s " S ^



? "i ?
2 g S

O O O C3 O
^° ° z ° z






E S
"^ S CN CN C%


























o g

S CD r*


VN U-i
o o
•^ T]

O ^
o c:
ro"






—



-------
                                                                                                      If.
21608
Federal Register/Vol. 65, No. 78/Friday, April 21,  2000/Proposed Rules

3 S "i
•sgi
ei o '—

0 C ° S
g o "S
O ft> "^
Jo
o
=1
Is

_ o
w S 3
fo *a
s i
£2 =
O (O f>
o §1
ft> 63
||

so
O
.-
if

§••§
0. «

J2
cs
VO
•O f.
lit
e J |
vo S3
ST c ®

o
°<3 o
» S
•85
"o "^
z"



















o
S

O
s







o









v>




















o
£

CM
m







U








P

g

vn
X



0
3
^^

O
0
o
CM







c
Cs
*



















«?


vb
^



O
VO
oo
__,

§
"p—








e\




















c?


oo




o
N
\J

s








r-v

^
c
CO



o
c




o
~
k—p

"O
—
s
vo
t-^
.—
o


rf,
•*•











•,)




^
o
3






















0
/I
>rt















r
o
4



















o


o




o
g
m

o








vrt

r?



















9
vo


J



S

MM

O
O
0
fn






,
:
o
-=









c
c^
VI



—
^*
C
en
CI
A
"

^
m



?
o
CM

0
o
CO









O
$



















A
£

s
CM
»






u








n
o
-=



















A
V

0
—







O









o
•o



















rA
vo










O









o
•=



















s;
4

ja;
vo



0
c


o
0
Cv









o
•»



















^
cr>
V

0
vc







O









o
'



















0
^

Z)
**



o
j;


o
3









o
'



















r;
5

0
fM



O
4)
VO
_^

O
o









o
Q






















O ?
vC
















CO CO
o o
p o/



















£
r\


§
VO






)








S
o
00























o


















)

-------
Federal Register/Vol. 65, No. 78/Friday, April 21,  2000/Proposed Rules
21609
a H »
.U 0 •—
.— fc ^~
il ||
g o -3

O o "IS
CM .
o
§~
£ o\
CO v*


Pi
£ as 3
S 2 X
501 tn
I "2
SI
o* £2
C3 OT
X

•S
CS

J.S.
i i
If
«
.—
VO
r-
Cx
Ht
ill
^o G 1^.
KT c °
S °
= 1
1 c
*^ 3
4> O
T^ .£-.
"» S
3 °*



















S
—

«
10


0
oo

o







o
"
oo



















4
r-i

o
3


o

0







_-
1 '
<



















°
^

r^
CM


1
OO

o







G*

•o
O



















I
oi

00
Ov


O
CN









tr»
.._
S



















o
ex
—

u\
C-)


C3









>/">
"
•o



















O
—

0
5


1

o
0







c
I
JE






















o
§
o












.
£



















o
CM

rr
r->


O
•n









5
^,
5



















u
CN
to

>o



rj-
rr

g








,
£



















S
£
«

O
r^


?

0
o







f^
•— •
5



















o
oc
CN

O
5




U







_^
N
CO



















f*1
—

o
CN




CJ







™
N
5



















i
o4

^o
rr


VTi
1

o







m
s
5



















ON
CN

m
CM




O







\o
N
5



















1
CM

O
9O


V%
C3
U

0







CN
N
CO



















s
CN

n
«->


o









^.
N
-0
GO



















^
CN

O
CV


1

0







«o
rsi
i



















I
-

•«•
•°




o







>o
CN
^
CO



















1
—

o
OC




o









>
CO



















A
CN

OO
OO




p-







-^
01
3



















^
-

O
jV,




a







c\
CN
CO



















o
ft
-

0
3-


?

S







»o
CN
>



















4
CN

O
^


.62e-05

0
o









>



















4>


M
«


1

0
o
CN







C

>



















<
^

o
^.


£j

o
o
0
CN"









>

-------
21610
Federal Register/Vol. 65, No. 78/Friday, April 21, 2000/Proposed Rules

S ° ">
111
-Is
ell
— £ S -
•g-J s?i

2 o "5
«. -a t>
o o •-

.c
•s
If
(Q .it
»- §
S = -0
g.s-g
S « 3


5 S "3
S =>

i^
5.



1
2
1 £
•a g
f8 §
*j
CA «£
£
C/5
J2

VO
f»
s Is.
ill
VO 0 ^
r~ e s
£ o
"3^
*—' 3
O O
12 —





















s
rJ


S




o
s
T


§




s
d\
—




















o
oo


o
0
oo
vrT









a




j=
A





















o
5


r—




o
00
r—


o
CM




12
r-




















0
m
CM

o
OO




o
0
f^)


0




CM

























0
o
0.
cs













>j





















o
o
04

0
o
p-^
o"









o


















ffl
I
_c
1

U1
—
J$
o>
_c

s
0
-

5














^





















0
CD


00




o
s
r^







VO





















o
^
oo

OJ




=>
CM
^y







Ov





















o
6

o
0
c
o
CM








J
a
"l
1
c

«
"^3
u
o
5s
o

-

§
2



1

_»


o
oo



»

0




















o
£
-

s




=>
oo
TT
«—


t




r?
o




















o
^J
-

00




o
CM
I^-
CM


o
CO





o




















o
X
-

£




o

CM


o
=>





0




















IO
0.
-

VC
CM








o




CO
a




















o
VO
-

CM"




C3
K
r^)


vo




—
O3
























O
CM















a
























S
CM"














m
CO
























c
o"
»n
O4













CO

-------
Federal Register / Vol. 65, No. 78/Friday, April 21, 2000/Proposed Rules
21611

-o


-S H 1
04 §^
If L
S o ~a ~
o"g-2
o w 'c
5 o
<*.
o
3
S '""'
3 S
ca .i

v) d O

g ^ =§
B Z I
<3 S-S
g S
£ "2
S s
CO "
E

CO
1
•- ^
•= I"
i I
Q. 0
a. o
os —
OS «
•i
5
r-
ON
Is >.
.= •52
is s
NO £> ^
r*- f- «
2 o
CM
O
"T —
•5 o
H? S2
• — 3
0 0
"" Si
3 "

























0
u

I
en"







O











S
CEt
ca

























o
u
PT

OO





3.9Ie-05


o
Cv











O





3.93e-05


o
0
fO










5
o

























g
tn

s
~*




o
s


o
o











^
4>
V
«
r-
r
ro

O
CO





O\
NO
E

c

t;
"f
™
NO
P—

—
—
2
S
i

CN








O











?
O

























s
o

o
*"*




o
0
cs


s











"
£

























0
q

g
*~—




o
r
-------
21612
Federal Register/Vol.  65, No. 78/Friday, April 21, 2000/Proposed Rules
*!»
J2 £ £
C£ o — *
o
if!
llll
fc •rn o
o 3 •=
O S ~
J «
1
f? ON*
d ji
— O
t/j 13 O
§o ^
•g i

<3 = "S
g s
si
§> 5;
m



.ae
5v
ON
a
>v
— ">
*o ££
o £
|j

.22
i--
c\
lit
11|
s\ c a
o
T —
1 S2
u o


























S

ON


§
vC
—



O
o

0
o



,
vrt
^
Q























o
o

\o


o
CO
OO





o
-j

S




vo
i
c























o

U-i


S





o
to
CO

CD
C\




NO
NO
A
o~























o




o
en




0
XI
XT

O
0
ro




§
("
tu























C3
U

CS


0
oo
m




o
1

CD
•n



^
r^
,'
01























1

NO


0
— ~




o
o>
T>

o
o




£
F
t-























CD




O
(N
~~



O
ON

0




M
c
H























CD

O


CD
m
oo
«•







0




OS
2,
>•























o




o
m




o
5

0




v>
_.!,
>"























O

w^


VI


—


o
r-
«




o
1

o




S
«*i*
X























o

o\


OO





o
a

o




o

























Q>




O
ON
—



0
2

o




oo
T
>























9

OO


•^~
m




CD
g

O
0




00
J1
*























9

90


is
rs




o
—

o
o




10
,•
^~

















w
s—
C
r*

c





?
\s)







o
o
o_




a

























9

ON


CO
oc
_




o
NO

o




3
A
^























4>

—


§
fS|

" *


0
X3

0
CD




O
»>
cc























s




^
...




o


s




oo
oo

























o

-a-


NO
(SJ





2

fS




0
CO
o























?

•


UN
VO
^«




O
0
<=>

1




s
CO
o























s

NO


1
»r




o
u
oo
oo

0
\o




o
—
—























s
1>

0


ON





9
tU
cs

§




M
—
~























c

>o


1
^




0
C>J

0
OS




V
—
—

-------
Federal Register/Vol.  65, No. 78/Friday, April 21, 2000/Proposed Rules
21613


•o
j° i.=
^ g.§
*§--
.I? *g o
H «>
= |:i -
1^*1
g o "5
O ^ 'j3
uj-g
o
3
5 S^
-3 ^
CQ ^
_ o
w OJ o
S C J3
§•21
e s g
£ "Z. *—
O CA C/I

a> «
£ C
ON S
"C
*-*

J5
.—
J2
if
o E
£-§
s. «
ON *

1
1
1 I1-
•2 ° t
1||
r^ _. "S
2 §
t^.
o
"T —
"5 o
£• "
•0 f
Is
3 ^^





























0
V

O
30




0
—

0
o
<"1








—
i





























1
r-
C4
§
•*



o
r->

o
<-T







S
a.





























o
S

g




g
•i
oo


>
o
c




o







o








2
3





























S
«o

O
ro




0
ff

1








CO
3

9
o
Irt

§








I

»



"3
JS

NO
r-

5
o
2:














0





c\
c\
3


.£
"c

s
CN

O
of






O








c>
CN
CO
o

o
r^
CN

CD
C








vC
CQ
2C



"3
wi

NO

ON
C
O












O








0
CD

VI
CD
1
—

O
CO
oo








\c
££
21



.c
^

vo
r-
ON
c
"c












a








o






























•V
o
s

o
en"



s
1

o
o








o






























rr
o
I

ca




CD
5

o
0








0

































CD
CD
0
""5"















O

































3
rn"
CO















oo

































g
od"
v-i















»






























s
^

NO




CD
1
cn
o
0
—







s
JD





























S
oo
oc

o
CN






a








§
rf





























c
S
r^
~*







a








o
-=





























0
c
CN
oo
CN






u








-
f





























c:
oc

cs







a








2
u





























s
JS

30
—






O
Z








s
L.





























S
o

N£




V*.
1
CN

O








O
tS

-------
21614
Federal Register/Vol. 65, No.  78/Friday, April 21, 2000/Proposed Rules
Si*

cs
en

O
*"*





u


o
3

















§

cc
-"

0
m
CM





U


o
CM
CU

















o
o
?








1
cs
0.













SO
o
^O
VO
"*

vO






O


fN
s













~i
r*
CM

-------
                     Federal  Register/Vol. 65,  No.  78/Friday, April 21,  2000/Proposed Rules
                                                                             21615
  d. Uranium. Since the 1991 proposal, a
number of new studies have been published
in peer-reviewed journals. A literature search
was conducted and covered the time period
between January 1991 to July, 1998.
Databases searched were TOXLINE,
MEDLINE, EMBASE, B1OSIS, TSCATS and
Current Contents (see EPA 2000a). The
results of the literature search were reviewed
and articles were identified, retrieved and
reviewed and analyzed. Subsequently, the
Toxicological Profile for URANIUM (Update)
was published extending the database to
September 1999 (see EPA 2000a).
  i. Health Effects in Animals. The potential
toxic effects of uranium following oral
exposures have been evaluated in recent
animal studies (see EPA 2000a). In a 28-day
range-finding study, male and female
Sprague-Dawley rats (15/sex/group) were
administered concentrations of 0,0.96, 4.8,
24,124, or 600 mg uranyl nitrate/L (UN/L)
in drinking water for a period of 28 days.
Results of the study showed no significant
dose-related effects on body weight gain,
food intake, fluid consumption, clinical
signs, or hematological parameters of treated
animals when compared with control
animals. Histologic examinations indicated
no statistically significant differences in the
incidence of a particular lesion in animals in
the 600 mg UN/L treatment group when
compared with animals in the control group.
However, a slight increase in the number of
affected animals in the 600 mg UN/L group
was observed, when compared with the
control group.
  As discussed in the Technical Support
Document (EPA 2000a), the long-term effects
of exposure to low-levels of uranium in
drinking water has been demonstrated.
Female rabbits and male albino rats were
exposed to 0, 0.02, 0.2, and 1 mg/kg uranyl
nitrate for 12 months or 0.05, 0.6, 6, and 60
mg/L uranyl nitrate for 11 months,
respectively. Results  of the study indicated a
decrease in acid phosphatase activity in the
spleens of rabbits in the 1 mg/kg group, but
not in rats, when compared to controls. A
statistically-significant (p<0.05) increase in
serum alkaline phosphatase activity was
observed by the eleventh month of exposure
in rats in the 6 and 60 mg/L groups, when
compared with controls. A statistically-
significant decrease in the content of nucleic
acids in the renal and hepatic tissues was
observed in rats in the 60 mg/L group and in
rabbits in the 1 mg/kg group, when compared
•with controls.
  ii. Health Effects in Humans. Recent
epidemiological studies have evaluated the
effects observed in humans exposed to
uranium in the drinking water (see EPA
2000a). These studies demonstrate the
relationship between uranium levels in the
drinking water and urine albumin, an
indicator of renal dysfunction, was
evaluated. Three sites were selected for the
controls (site 1) and the exposed groups (sites
2 and 3), with mean uranium water levels of
0.71,19.6 and 14.7 ug/L reported for sites 1,
2 and 3, respectively. An index of uranium
exposure was estimated for each study
participant by multiplying the uranium
concentration in the water supply by the
average number of cups consumed at each
residence and the total number of years at  ,
that residence. Based on the results of a
linear regression analysis, which included
terms for age, diabetes, sex, smoking, and the
use of water filters and softeners, a
statistically-significant association was
reported for cumulative exposure to uranium
and urine albumin levels. However, the
authors noted that for most of the study
participants, the urine albumin levels were
within the range of normal values.
  A recent study of a village in Nova Scotia
(see EPA 2000a) demonstrated the renal
effects following chronic exposure to
uranium in the drinking water. -Two groups
were evaluated, a  low exposure group
(uranium levels < 1/L) and a high exposure
group (uranium levels > lug/L). Twenty-four
hour and 8-hour urine samples were
collected and evaluated for uranium,
creatinine, glucose, protein, ba-microglobulin
(BMG), alkaline phosphatase (ALP), gamma
glutamyl transferase (GGT), lactate
dehydrogenase (LDH), and N-acetyl-b-D-
glucosammidase (NAG). Statistically
significant positive correlations were
reported with uranium intake for glucose
(males, females and pooled data), ALP
(pooled data) and BMG (pooled data). No
other statistically  significant differences were
reported. Based on these results, the authors
concluded that the proximal tubule was the
site of uranium nephrotoxicity.
  In June 1998, a workshop was held by the
USEPA to discuss issues associated with
assessing the risk  associated with uranium
exposure and updating the RfD and MCLG
for uranium. The numerous technical issues
associated with the development of a risk
assessment for uranium in drinking water
were discussed. Based on these discussions,
it was apparent that there is a range of values
for each factor used in the development of
the RfD and MCL  for uranium. However,
based upon the input received at the
workshop and the most current information,
EPA believes that the LOAEL for renal effects
in male rats of 0.06 mg U/kg/day reported
could be used for the development  of an RfD
for uranium (see EPA 2000a). The relative
source contribution (RSC) was revised to 80
percent (0.8). The total uncertainty factor was
determined to be about 100 (about 3 for
animal to human extrapolation, about 10 for
intraspecies differences, about 1 for a less
than lifetime study, and about 3 for the use
of a LOAEL), with the body weight of 70
kilograms (kg) and daily water consumption
of two liters used  in the calculation. These
assumptions are consistent with the data
presented at the workshop and appear to be
reasonable and justifiable. EPA believes these
factors allow for the calculation of a safe
level of uranium in drinking water  (in terms
of chemical toxicity).
  The application of the total uncertainty
factor of 100 to the LOAEL of 0.06 mg/kg/day
results in an RfD of 0.6 ug uranium/kg/day.
The RfD can be used to determine the MCL
by multiplying the RfD by body weight (70
kg) and RSC (0.8) and dividing by water
consumption (2 L), resulting in a value of 17
ug uranium/L, which can be rounded off to
20 /L.
2. Consideration of Sensitive Sub-
populations: Children's Environmental
Health
  In compliance with Executive Order 13045
"Protection of Children from Environmental
Health Risks and Safety Risks" (62 FR 19885,
April 23,1997), risks to children from
radionuclides have been considered. There is
evidence that children are more sensitive to
radiation than adults, the risk per unit
exposure in children being greater than in
adults.
  Risk coefficients used by the Agency for
radiation risk assessment explicitly account
for these factors. The age-specific, organ-
specific risk per unit dose coefficients used
in the lifetime risk model apply the
appropriate age-specific sensitivities
throughout the model. The model also
includes age-specific changes in organ mass
and metabolism. The risk estimate at any age
is the best estimate for that age. In developing
the lifetime risks, the model uses the life
table for a stationary population. Use of the
life table allows the model to account for
competing causes of death and age-specific
survival. These adjustments make the
lifetime risk estimate more realistic.
  At the same time,  consumption rates of
food, water and air are different between
adults and children. The lifetime risk
estimates for radionuclides in water use age-
specific water intake rates derived from
average national consumption rates when
calculating the risk per unit intake. Since the
intake by children is usually less than the
intake by adults, it tends to partially mitigate
the greater risk in children compared to
adults when evaluating lifetime risk.

D. References
  EPA, 1999.  Cancer Risk Coefficients for
Environmental Exposure to Radionuclides,
Federal Guidance Report No. 13. US
Environmental Protection Agency,
Washington, DC, 1999. Uranium Issues
Workshop—Sponsored by United States
Environmental Protection Agency,
Washington, DC ; June 23-24,1998.
  USEPA. "Technical Support Document for
the Radionuclides Notice of Data
Availability." Draft.  March, 2000. (EPA
2000a)

Appendix ffl—Analytical Methods
  Table IH-1 briefly summarizes the
regulatory events associated with:
  • The testing procedures for regulated
radionuclides approved in 1976;
  • Major analytical additions or changes
proposed or discussed in the 1991
radionuclides rule;
  • Testing procedures and protocols
approved in the March 5,1997—
radionuclides methods rule (62 FR 10168,
cited in 40 CFR 141.25); and
  • Items discussed in today's NODA.

-------
21616
Federal  Register/Vol. 65, No. 78/Friday, April  21, 2000/Proposed Rules
        TABLE 111-1.—BRIEF SUMMARY OF THE REGULATORY EVENTS ASSOCIATED WITH RADIOCHEMICAL METHODS
 1976 National primary drinking
       water regulations
          July 18, 1991—Radionuclides
                proposed rule
 March 5, 1997-Radionuclide
      methods final rule
     Today's notice of data availability
The 1976 NPDWR approved:
* Radiochemical methods to
  analyze for gross alpha-par-
  ticle activity, radium-226.
  total radium, gross beta-par-
  ticle activity, strontium-89
  and -90. cesium-134 and
  uranium
* Defined the detection limit
  (DL) as the required measure
  of sensitivity and listed the
  required DL for each regu-
  lated radionuclide
         The   July  18,  1991—radio-
           nuclides rule proposed:
         * Fifty-six  additional  methods
           for compliance monitoring of
           radionuclides
         * Guidance for the sample han-
           dling,  preservation and hold-
           ing  times that  were cited in
           the  1990 U.S.EPA "Manual
           for the Certification of Lab-
           oratories Analyzing Drinking
           Water"
         *The use of practical quantita-
           tion limits (PQLs)  and  ac-
           ceptance limits as the meas-
           ures   of    sensitivity   for
           radiochemical analysis
The  March 5,  1997 final rule
  for radionuclide methods:
'Approved 66 additional radio-
  nuclide techniques for gross
  alpha-particle   activity,   ra-
  dium-226,  radium-228,  ura-
  nium,   cesium-134,  iodine-
  131, and strontium-90
Responded to comments  re-
  garding the analytical meth-
  ods  (excluding  radon)  re-
  ceived  from  the  July  18,
  1991 proposed radionuclides
  rule
Updates the public on changes that have
  occurred  regarding radiochemical meth-
  ods of analysis since the 1991 proposed
  rule. The updates discussed in today's
  NODA include:
*A brief discussion of the analytical meth-
  ods updates which were promulgated by
  the Agency on July 18, 1997 final rule.
* Guidance for the sample handling, preser-
  vation and  holding times  listed  in the
  1997  U.S.EPA "Manual  for the  Certifi-
  cation of Laboratories Analyzing Drinking
  Water."
'Recommendations  for  the  analysis of
  short-lived,  alpha-emitting  radioisotopes
  (i.e., radium-224).
'Revised cost  estimates for radiochemical
  analysis.
"The Agency's intent to continue to use the
  detection  limits defined in the 1976 rule
  as the required measures of sensitivity.
* Response, to  some of the comments on
  the 1991 proposed radionuclides.
* The externalization of  the  Performance
  Evaluation Program.
The  Agency's  plans to implement a  Per-
  formance Based Measurement System.
A. The Updated 1997 Laboratory
Certification Manual
  A revised version of the certification
manual was published in 1997 (EPA 815-B-
                      97-001, EPA 1997b). Table IH-2 lists the
                      guidance for sample handling, preservation,
                      holding times, and instrumentation which
                      appeared in this manual. Table III—2 also
                          includes additional recommendations for
                          radiochemical instrumentation (footnoted by
                          the number 6), which the Agency is
                          requesting comment on.
                 TABLE III-2.—SAMPLE HANDLING, PRESERVATION, HOLDING TIMES AND INSTRUMENTATION
Parameter
Gross Alpha 	
Gross Beta 	 	 	 . 	 . 	
Radium-226 	 	
Radium-228 	
Uraniurn natural 	 	 	
Ceskim-134 ...
Stronlium-89 and -90 	
Radioactive lodine-131 	
Tritium . ... .. ....
Gamma/Photon Emitters 	
Preservative '
Concentrated HCI or HNO3 to pH <2=
Concentrated HCI or HNO3 to pH <25
Concentrated HCI or HNO3 to pH <2 ..
Concentrated HCI or HNO3 to pH <2 ..
Concentrated HCI or HNO3 to pH <2 ..
Concentrated HCI to pH <2
Concentrated HCI or HNO3 to pH <2 ..
None 	
None 	
Concentrated HCI or HNO3 to pH <2 ..
Container2
PorG
P orG
PorG
PorG
P orG
PorG
P orG
PorG
G
PorG
Maximum holding
time3
6 months
6 months
6 months
6 months
6 months
6 months
6 months
8 days
6 months
6 months
Instrumentation 4
A, B or G
A or G
A, B, C6, DorG
A, B«, C«orG
A6, F, G6, or O
A C or G
A orG
A, C or G
E
C
  11t is recommended that the preservative be added to the sample at the time of collection. It is recommended that samples be filtered if sus-
pended of settleable solids are present at any level observable to the eye prior to adding preservative. This should be done at the time of collec-
tion. If the sample has to be shipped to a laboratory or storage area, however,  acidification  of the sample (in its original container) may be de-
layed for a period not to exceed 5 days. A minimum of 16 hours must elapse between acidification and start of analysis.
  * P = Plastic, hard or soft; G = Glass, hard or soft.
  3 Holding time is defined as the period from time of sampling to time of analysis. In all cases, samples should be analyzed as soon after collec-
tion as possible. If a composite sample is prepared, a holding time cannot exceed 12 months.
  *A s Low background proportional system; B = Alpha and beta scintillation system; C = Gamma spectrometer [Ge(Hp) or Ge  (Li)]; D = Scin-
tillation cell system; E = Liquid scintillation system; F =  Fluorometer; G  = Low background alpha and beta counting system other than gas-flow
proportional; O - Other approved methods (e.g., laser phosphorimetry and alpha spectrometry for uranium).
  s If HCI is used to acidify samples which are to be analyzed for gross  alpha or gross beta activities, the acid salts must be converted to nitrate
salts before transfer of the samples to planchets.
  8 Additional Instrumentation that was not listed in the USEPA 1997 "Manual for the Certification of Laboratories Analyzing Drinking Water."
B. Recommendations for Determining the
Presence of Radium-224
  To determine the presence of the short-
lived radium-224 isotope (half life -3.66
days), the Agency recommends using one of
the following several options.
                      1. Radium-224 by Gamma Spectrometry and
                      Alpha Spectrometry

                        (a) Gamma Spectrometry. Radium-224 can
                      be specifically determined by gamma
                      spectrometry using a suitably prepared
                      sample. In this method a precipitate in which
                          the radium isotopes are concentrated is
                          gamma counted. The primary advantage of
                          this technique is specificity for radium
                          gamma rays, radium-224 included. Other
                          advantages of this method include:

-------
                     Federal  Register/VoI. 65, No.  78/Friday, April  21, 2000/Proposed Rules
                                                                             21617
  • a simple sample preparation were
radium isotopes are concentrated from
samples 1 liter or larger;
  • specificity for the radium-224 isotope
based on a unique gamma energy;
  • optimal accuracy and precision if the
sample is counted within 72 hours of
collection (40 hours is recommended);
  • and is cost competitive with the gross
methods because a single count rather that
three counts (see the gross alpha methods
discussion) is necessary to measure the
radium-224 in a routine sample.
  A gamma spectrometry method by
Standard Methods is currently pending but
for now the reader is referred to the method
used by Parsa. (Parsa, 1998).
  (b) Alpha Spectrometry. The alpha
spectrometry method measures alphas
emitted by radium-224 and its alpha emitting
daughters. The alpha spectrometry method,
used for the USGS occurrence survey (see
appendix I and EPA 2000a), was a slight
modification of an existing method (see EPA
2000a). Using an appropriate tracer (e.g. Ba-
133), barium and radium isotopes are
separated from other radionuclides and
interferences using cation ion exchange
chromatography. A prepared sample,
counted for approximately 100 minutes using
alpha spectrometry, can be used to measure
the radium-224 in the sample and is capable
of good accuracy and precision. Other alpha
spectrometry techniques, similar to the
modified method used for the USGS
occurrence survey, should be sufficient for
the detection of radium-224. It is cost
competitive with the gross methods
(discussed next) because a single count rather
than three (for gross methods) is sufficient to
for measurement of radium-224.
2. Gross Radium Alpha (Co-precipitation)
Within 72 Hours
  The presence of radium-224 can be
determined indirectly using the radium-224
half-life decay and the gross radium alpha
technique. Gross radium co-precipitation
methods, like EPA 903.0, concentrate radium
isotopes by co-precipitation,-separating
radium and radium-like isotopes from
potential interferences. Relative to
evaporative methods, the co-precipitation
technique can be used for larger (> 1 L)
sample sizes with a resulting increase in the
method sensitivity. Initial analysis within 72
hours after sample collection (40 hours
recommended for optimal data quality) using
the co-precipitation methods yield results,
reflecting both alpha-emitting radium
isotopes (radium-224 and radium-226). For
these to produce unambiguous results,
radium-224 must be the dominant isotope
present, i. e. the ratio of radium-224 to
radium-226 must be three or greater. If this
is the prevailing composition, the estimated
contribution of radium-224 to the overall
value can be ascertained by recounting the
sample at 4 or 8 days intervals and
calculating the change in the measured
activity. The noted change will show a
decrease with a 4 day half-life indicative of
Ra-224. Formulas are available to calculate
the initial radium-224 concentration present
in the sample when collected. The
advantages of this technique include:
  • enhanced sensitivity (>1 L samples);
  • it does not require additional analyst
training;
  • it is specific for radium isotopes; and
  • the resulting precipitate can be measured
by a number of techniques, including
proportional counting, alpha scintillation
counting, or gamma counting.
3. Evaporative Gross Alpha-Particle Analysis
Within 72 Hours
  The radium-224 isotope, when in
equilibrium with its decay progeny, emits
four alpha particles. Three of these alpha
particles equilibrate almost immediately
(within 5 minutes) after sample preparation
and add to or amplify the sample count rate.
This count rate amplification can be
exploited for the measurement of radium-224
in a sample at low concentration (<15 pCi/
L). The presence of the radium-224
radioisotope in drinking water may be
ascertained by performing an initial
evaporative gross alpha-particle analysis
within 72 hours (40 hours recommended)
after sample collection, hi the absence of any
other alpha-emitting nuclide (e.g., uranium
or radium-226) and if the gross alpha-particle
value is above the MCL, the sample may be
re-counted at 4- and 8-day intervals to
determine if the observed decrease in activity
follows the 3.66 day half-life of radium-224.
A decrease in the gross alpha value with a
4-day decay rate indicates the likely presence
of radium-224. Formulas are available to
calculate the concentration of radium-224 in
the initial sample. The advantages of this
option include:
  • the method is similar to the general
method for evaporative gross alpha;
  • it requires no special training of the
analyst; and
  • it can be a definitive test if other alpha-
emitting nuclides are known to be absent.
,  The Agency recognizes that analysis within
the 72-hour time frame creates difficulties in
shipping and handling and may increase the
price of the analysis.

C. Revised Cost Estimates for Radiochemical
Analysis
  The cost estimates for radiochemical
analysis from the 1991 proposed rule and the
revised cost estimates are shown in Table III—
3.
                TABLE 111-3.—THE 1991 AND 1999 ESTIMATED COSTS OF ANALYSES FOR RADIONUCLIDES
Radionuclides
Gross Alpha and beta 	 	 	 , 	
Gross alpha — coprecip. 	 	 	 , 	
Radium-226 	 	 	
Radium-228 	
Uranium (total) 	 , 	 •
Uranium (isotopic) 	 	
Radioactive Cesium (-134) 	 , 	 	 	
Radioactive Strontium 	 , 	
Total Strontium (-89 and -90) 	
Radioactive iodine -131 	 , 	 , 	 , .
Tritium 	 	 	
Gamma/Photon Emitters 	 	 	
Approximate
costs (1991)1
35
35
85
100
45
125
100
105

100
50
110
Approximate
costS (1 999)2
AC.
AK.

1 10
AO (] p\
-toe f&<2\


153

60
142
  Source:
  156 FR 33050; July 18, 1991.
  2USEPA, 2000a.
  Abbreviations: LP = laser phosphorimetry; AS = alpha spectrometry.
  Note: Estimated costs are on a per-sample basis; analysis of multiple samples may have a lower cost.

-------
21618
Federal  Register/Vol.  65, No. 78/Friday,  April  21, 2000/Proposed  Rules
D, The Detection Limits as the Required
Measures of Sensitivity
  Table 111-4 cites the detection limits or the
required sensitivity for the specific
radioanalyses that were listed in the 1976
rule and are also cited in 40 CFR 141.25.

TABLE  III-4.—REQUIRED REGULATORY
   DETECTION  LIMITS  FOR THE  VAR-
   IOUS    RADIOCHEMICAL    CONTAMI-
   NANTS (40 CFR 141.25)
Contaminant
Gross Alpha 	
Gross Beta 	 ..
Radium-226 ......
Radium-228 	 	 	
Cestum-134 	 	 	
Strontium-89 	 	 	 .
Strontium-90 ,... 	
todine-131 	 	 	
Tritium 	 	 	 	 ....
Other Radionuclides
and Photon/
Gamma Emitters.
Detection limit (pCi/L)
3
4
1
1
10
10
2
1
1,000
Vioth of the rule
NIPDWR 1976
table IV-2A and 2B
E. References
  Parsa, B., 1998. Contribution of Short-lived
Radionuclides to Alpha-Particle
Radioactivity in Drinking Water and Their
Impact on the Safe Drinking Water Act
Regulations, Radioactivity and
Radiochemistry, Vol. 9, No. 4, pp. 41-50,
1998. USEPA, 1991. National Primary
Drinking Water Regulations; Radionuclides;
Proposed Rule. Federal Register. Vol. 56, No.
138. p. 33050. July 18,1991.
  USEPA. 1997a. National Primary Drinking
Water Regulations; Analytical Methods for
Radionuclides; Final Rule and Proposed
Rule,  Vol. 62. No. 43, p. 10168. March 5,
1997.
  USEPA, 1997b. "Manual for the
Certification of Laboratories Analyzing
Drinking Water." EPA 815-B-97-001.1997.
  USEPA, 2000a. "Technical Support
Document for the Radionuclides Notice of
Data Availability." 2000.
Appendix IV—Treatment Technologies and
Costs
A, Introduction
  This section describes updates to EPA's
previous evaluations of the feasibility and
costs of treatment technologies for the
removal of radionuclides from drinking
water. Prior to this update,  the latest
evaluation was the 1992 "Technologies and
Costs document" for radionuclides in
drinking water (EPA 1992). The updates to
the 1992 radionuclides Technologies and
Costs document comprise an updated
Technologies and Costs Document (EPA
1999a) and a radium compliance cost study
(EPA  1998a), which are described later in
this section. This section also describes other
relevant documents, including thel998
Federal Register notice of the "Small
Systems Compliance Technology List"
(SSCTLs) for the currently regulated
radionuclides (63 FR 42032) and its
supporting guidance document (EPA 1998b).
Both of the documents supporting the SSCTs
                      can be obtained on-line at "http://
                      www.epa.gov/OGWDW/standard/
                      tretech.html".
                        The SSCTLs for the meeting the MCLs for
                      combined radium-226 and radium-228, gross
                      alpha emitters, and combined beta and
                      photon emitters are included in
                      "Announcement of Small System
                      Compliance Technology Lists for Existing
                      National Primary Drinking Water Regulations
                      and Findings Concerning Variance
                      Technologies," published in the Federal
                      Register on August 6,1998 (63 FR 42032).
                      The supporting guidance document cited
                      previously includes information regarding
                      small systems treatment and waste disposal
                      concerns relevant to radionuclide
                      contaminants and was made publicly
                      available on September 15,1998. Further
                      evaluations of small systems treatment
                      technology applicability and affordability
                      have been done since the SSCTLs for
                      radionuclides were published, including an
                      analysis of SSCTs for uranium (EPA 1999b).
                      These evaluations are summarized later in
                      this section.

                      B. Treatment Technologies Update
                      1. Updates on Performance of Technologies
                      for Removal of Regulated Radionuclides and
                      Uranium
                        One of the purposes of the update to the
                      radionuclides Technologies and Costs (T&C)
                      document (EPA 1999a) was to update the
                      treatment technology performance sections of
                      the 1992 radionuclides T&C document. The
                      peer-reviewed literature revealed no new
                      significant sources of information regarding
                      performance for the previously described
                      technologies, nor did it reveal literature
                      regarding any new treatment technologies for
                      radionuclides in drinking water. Both the
                      1992 and 1999 radionuclides T&C documents
                      include performance evaluations of the BATs
                      proposed in 1991 for the regulated
                      radionuclides and uranium (56 FR 33050, Jul.
                      18,1991) and additional technologies  that
                      were reviewed as potential BATs for the 1991
                      proposed rule, but that were not proposed as
                      BAT for various reasons.
                        Although the 1999 T&C document
                      concludes that the peer-reviewed literature
                      describes no new technologies since the 1992
                      T&C document was completed, there have
                      been some developments that are significant.
                      In particular, both package plant'
                      technologies, including those equipped with
                      remote control/communication capabilities,
                      and point-of-entry (POE)/point-of-use  (POU)
                      versions 2 of existing technologies have
                        1 Package plants are skid mounted factory
                      assembled centralized treatment units that arrive on
                      site "virtually ready to use". Package plants offer
                      several advantages. First, since they combine
                      elements of the treatment process into a compact
                      assembly (such as chemical feeders, mixers,
                      flocculators, basins, and niters), they tend to require
                      lesser construction and engineering costs. Another
                      advantage is that many package plant technologies
                      arc becoming more automated and thus can be less
                      demanding of operators than their fully engineered
                      counter-parts (EPA 1998b).
                        2 Point-of-entry (POE) treatment units treat all of
                      the water entering a household or other building,
                      xvith the result being treated water from any tap.
                      Point-of-usc (POU) treatment units treat only the
become more widely applicable for use for
compliance. This is true both because of
improvements in these technologies
themselves (NRC 1997) and since the 1996
SDWA explicitly allows package plants and
POE/POU devices to be used as compliance
technologies for small systems (section
1412.b.4.E). Package plant technologies and
POE/U technologies are discussed in more
detail in the Technical Support Document
(EPA 2000a).
2. Treatment Technologies Evaluated as
Compliance Technologies for Radionuclides
  The following technologies are reviewed in
the 1999 radionuclides T&C document: (1)
for radium, the 1991 proposed Best Available
Technologies (BATs), which are lime
softening, ion exchange, and reverse osmosis;
and two other applicable technologies with
significant radium removal data,
electrodialysis reversal and greensand
filtration; (2) for uranium, the 1991 proposed
BATs, which are coagulation/filtration, ion
exchange, lime softening, and reverse
osmosis; and two other applicable
technologies, electrodialysis reversal and
activated alumina; (3) for gross alpha particle
activity, the 1991 proposed BAT, which is
reverse osmosis; and one other applicable
technology, ion exchange; and (4) for beta
particle activity and photon radioactivity, the
1991 proposed BATs, which are ion
exchange and reverse osmosis. No other
technology studies pertinent to total beta and
photon activity were found, but this is largely
due to the fact that treatment applicability
depends on what specific beta and photon
emitters are present and so should be
evaluated on a case-by-case basis. This
consideration also applies to gross alpha
activity. It is likely that reverse osmosis,
being applicable to a broad range of inorganic
contaminants, including radionuclide
contaminants, is the best alternative for
situations where multiple radionuclides
occur.
3. Data on Additional Treatment
Technologies
  The 1999 radionuclides T&C document
does not identify any new treatment
technologies for radionuclides, but does
provide information on two additional
variants of coagulation/filtration for uranium
removal: direct filtration and in-line
filtration.
4. Small Systems Compliance Technology
List and Guidance Manual for the Regulated
Radionuclides and Uranium
  The 1996 SDWA identifies three categories
of small drinking water systems, those
serving populations between 25 and 500, 501
and 3,300, and 3,301 and 10,000. In addition
to BAT determinations, the SDWA directs
EPA to make technology assessments for each
of the three small system size categories in
all future regulations establishing an MCL or
water at a particular tap or faucet, with the result
being treated water that one tap, with the other taps
serving untreated water. POE and POU treatment
units often use the same technological concepts
employed in the analogous central treatment
processes, the main difference being the much
smaller scale of the device itself and the flows being
treated (EPA 1998b).

-------
                      FederalRegister/Vol. 65,  No. -78 /Friday, April 21,  2 TOO/ Proposed Rules
                                                                                                                        21619
 treatment technique. Two classes of small
 systems technologies are identified for future
 National Primary Drinking Water Regulations
 (NPDWRs): compliance technologies and
 variance technologies.
   Compliance technologies may be listed for
 NPDWRs that promulgate MCLs or treatment
 techniques. In the case of an MCL,
 "compliance technology" refers to a
 technology or other means that is affordable
 (if applicable) and that achieves compliance.
 Possible compliance technologies include
 packaged or modular systems and point-of-
 entry (POE) or point-of-use (POU) treatment
 units, as described previously.
   Variance technologies are only specified
 for those system size/source water quality
 combinations for which no technblogy meets
 all of the criteria for listing as a compliance
 technology (section 1412(b)(15)(A)). Thus,
 the listing of a compliance technology for a
 size category/source water combination
 prohibits the listing of variance technologies
 for that combination. While variance
 technologies may not achieve compliance
 with the MCL or treatment technique
 requirement, they must achieve the
 maximum reduction that is affordable
                                            considering the size of the system and the
                                            quality of the source water. Variance
                                            technologies must also achieve a level of
                                            contaminant reduction that is "protective of
                                            public health" (section 1412(b)(15)(B)).
                                              In the case of the currently regulated
                                            radionuclides, i.e., combined radium-226 and
                                            -228, gross alpha activity, and total beta and
                                            photon activity, there are no variance
                                            technologies allowable since the SDWA
                                            (section 1415(e)(6)(A)) specifically prohibits
                                            small system variances for any MCL or
                                            treatment technique which was promulgated
                                            prior to January 1,1986. The Variance and
                                            Exemption Rule describes EPA's
                                            interpretation of this section in more detail
                                            (see 63 FR 19442; April 20,1998).
                                              Small systems compliance technologies for
                                            the currently regulated radionuclides,
                                            combined radium-226 and -228, gross alpha
                                            emitters, and total beta and photon activity,
                                            were  listed and described in the Federal
                                            Register on August 6,1998 (EPA 1998a) and
                                            in an accompanying guidance manual (EPA
                                            1998b). Small systems compliance
                                            technologies for uranium were also evaluated
                                            (EPA 1999a). Small systems compliance
                                            technologies (SSCTs) for uranium were
                                   evaluated in terms of each technology's
                                   removal capabilities, contaminant
                                   concentration applicability ranges, other
                                   water quality concerns, treatment costs, and
                                   operational/maintenance requirements. The
                                   SSCT list for uranium is technology specific,
                                   but not product (manufacturer) specific.
                                   Product specific lists were determined to be
                                   inappropriate due to the potential resource
                                   intensiveness involved. Information on
                                   specific products will be available through
                                   another mechanism. EPA's Office of Research
                                   and Development has a pilot project under
                                   the Environmental Technology Verification
                                   (ETV) Program to provide treatment system
                                   purchasers with performance data from
                                   independent third parties.
                                    Tables IV-1 and IV-2 summarize the small
                                   systems compliance technologies listed in
                                   the 1998 SSCTL for combined radium-226,
                                   and -228, gross alpha emitters, total beta and
                                   photon activity. Table IV-1 is shown as it
                                   will be updated when uranium is regulated.
                                   Table IV—l describes limitations for each of
                                   the listed technologies and Table IV-2 lists
                                   SSCTs for each contaminant.
    TABLE iv-1.—LIST OF SMALL SYSTEMS COMPLIANCE TECHNOLOGIES FOR RADIONUCLIDES AND LIMITATIONS TO  USE
           Unit technologies
                                        Limitations
                                        (see foot-
                                          notes)
      Operator skill level required1
      Raw water quality range and
            considerations'
 1. Ion Exchange (IE)	
 2. Point of Use (POU) IE ..
 3. Reverse Osmosis (RO)
4. POU RO .
5. Lime Softening	
6. Green Sand Filtration	
7. Co-precipitation with Barium Sulfate ....
8. Electrodialysis/Electrodialysis Reversal
9. Pre-formed Hydrous Manganese Oxide
   Filtration.
10. Activated alumina	„...
11. Enhanced coagulation/filtration .
                                           (b)


                                           (b)
                                           (")
                                           O
Intermediate
Basic 	
Advanced ....
                                                     Basic
                                           (*)  '

                                          00. (h)
Advanced 	
Basic 	
Intermediate to Advanced
Basic to Intermediate	
Intermediate 	
                                                    Advanced
                                                    Advanced
All ground waters.
All ground waters
Surface waters usually require pre-filtra-
  tion.
Surface waters usually require pre-filtra-
  tion.
All waters.

Ground waters with suitable water quality.
All ground waters.
All ground waters.

All ground waters; competing anion con-
  centrations may affect regeneration fre-
  quency.
Can treat a wide range of water qualities.
  1 National Research Council (NRC). Safe Water from Every Tap: Improving Water Service to Small Communities. National Academy Press
Washington, D.C. 1997.
  Limitations Footnotes to Table IV-2: Technologies for Radionuclides:
  aThe regeneration  solution contains high concentrations of the contaminant ions. Disposal options should be carefully considered before
choosing this technology.
  bWhen POU devices are used for compliance, programs for long-term operation, maintenance, and monitoring must be provided by water util-
ity to ensure proper performance).
  c Reject water  disposal  options should  be carefully considered before  choosing this technology. See other RO limitations described in the
SWTR Compliance Technologies Table.
  dThe combination of variable source water quality and the complexity of the water chemistry involved may make this technology too complex
for small surface  water systems.
  = Removal efficiencies can vary depending on water quality.
  This technology may be very limited in application to small systems. Since the process requires static mixing, detention basins and filtration
it is most applicable to systems  with sufficiently high sulfate levels that already have a suitable filtration treatment train in place
  s This technology is most applicable to small  systems that already have filtration in place.
  h Handling of chemicals  required during regeneration and pH adjustment may  be too difficult for small systems without an adequately trained
operator.
  'Assumes modification to a coagulation/filtration process already in place.
  Table IV-2 lists the Small Systems
Compliance Technologies for the currently
regulated radionuclides. Technology
                                           numbers refer to the technologies listed in
                                           Table IV-1.

-------
21620
Federal Register/Vol.  65, No.  78/Friday,  April  21, 2000/Proposed  Rules
 TABLE IV-2.—COMPLIANCE TECHNOLOGIES BY SYSTEM SIZE CATEGORY FOR RADIONUCLIDE NPDWRS (AFFORDABILITY
                       NOT CONSIDERED, EXCEPT FOR URANIUM, DUE TO STATUTORY LIMITATIONS)
1
Contaminant



Total beta particle activity and photon activity,







Compliance technologies' for system size
categories (population served)
, 25-500 |, 501-3,300
1,2, 3,4, 5, 6,
7,8,9
3,4
1,2, 3,4
1, 2,4, 10, 11
1,2,3,4,5,6,
7,8,9
3,4
1,2,3,4
1,2,3,4,5,
10,11
3,300-10,000
1, 2, 3,4, 5,6,
7,8,9
3,4
1,2,3,4
1,2,3,4,5,
10, 11
  Mole: ' Numbers correspond to those assigned to technologies found in the table "List of Small Systems Compliance Technologies for the Cur-
rently Regulated Radionuclides."
C, Waste Treatment, Handling and Disposal
Guidance
  In the proposed radionuclides rule of July
1991, EPA referenced a 1990 EPA draft report
entitled "Suggested Guidelines for Disposal
of Drinking Water Treatment Wastes
Containing Naturally-Occurring
Radionuclides" (EPA 1990). That 1990 report
offered guidance to system managers,
engineers, and State agencies responsible for
the safe handling and disposal of treatment
wastes that, in many cases, were not
specifically addressed by any statute. That
guidance report was later updated in 1994
[EPA 1994).
  The guidance provided information on the
following: (1) Background on water treatment
processes and characteristics of wastes
generated; (Z) rationale for radiation
protection, including citation of programs
and regulations affecting other sources of
such waste; (3) guidelines for several
methods of disposal of solid and  liquid type
wastes containing the subject radionuclides;
and. (4) the specification of practical
guidance to protect workers and others who
may handle or be exposed to water-treatment
wastes containing radiation above
background levels.
  The Technical Support Document (EPA
2000a) discusses disposal methods and
issues, including comments received in
reference to the 1990 "Suggested Guidelines
for Disposal of Drinking Water Treatment
Wastes Containing Naturally-Occurring
Radionuclides," and the 1994 update to this
report.
D. Unit Treatment Cost Updates
  Treatment costs for coagulation/filtration
(including direct filtration and in-line
filtration), lime softening, ion exchange,
reverse osmosis, electrodialysis reversal,
greensand filtration, point-of-use (POU)
reverse osmosis, POU ion exchange, and
point-of-entry cation exchange were updated
in the appendix to the 1999 radionuclides
T&C document. This update includes land-
cost considerations and waste-disposal cost
estimates. Cost estimates were made using
standard EPA treatment technology costing
models. Outputs were updated to current
dollars using standard engineering costing
indices, e.g., the Bureau of Labor's Chemical
and Allied Products Index. Costs for
individual technologies were analyzed in
terms of water usage, removal efficiency,
interest rate, and other variables.
                        In addition to cost model updates, EPA has
                      performed a study of the actual costs of
                      treatment and other compliance measures for
                      the radium standard (EPA 1998c), which
                      provided a "snapshot" of the costs incurred
                      by water systems in complying with the
                      existing combined radium-226 and radium-
                      228 MCL. Studies of this nature allow EPA
                      to compare modeled costs used in regulatory
                      impact assessments with real-world data for
                      the purposes of model validation and cost
                      estimate amendments. They also allow EPA
                      to check assumptions about the prevalence of
                      use of particular water-treatment
                      technologies.
                        The study comprises data compiled from
                      contacts with water-treatment personnel,
                      State representatives, and EPA Regional
                      representatives within EPA Regions 5 (IL, IN,
                      MI, MN, OH, and WI) and 8 (CO, MT, ND,
                      SD, UT, and WY). Specifically, data were
                      obtained regarding water systems in
                      California, Florida, Idaho, Illinois, Indiana,
                      Ohio, Wisconsin, and Wyoming. State
                      Agencies and EPA Regional offices identified
                      136 systems as having water sources with
                      combined radium-226 and radium-228 above
                      the MCL of 5 pCi/L. Of these, 55 of the
                      systems were contacted, of which 29 were
                      either treating for radium or were in the
                      process of selecting a treatment method.  The
                      remaining systems were either further behind
                      in treatment selection plans or pursuing
                      other compliance measures. All of the
                      systems that were currently treating for
                      radium were in compliance with the MCL.
                      Twenty-six of these systems responded with
                      cost data, of which 17 were small systems
                      (design flow < 1 mgd). Thirty-five percent of
                      the small systems reported were using
                      reverse osmosis which, at an average total
                      treatment cost of S3.02 per thousand gallons,
                      was the most expensive treatment technology
                      identified. Other treatment options used were
                      lime softening and ion exchange. These had
                      average total treatment costs of S2.36 and
                      S0.73 per thousand gallons, respectively.
                      Unit costs are discussed in more detail in the
                      Technical Support Document (EPA 2000a).
                        EPA requests comments on its analysis of
                      treatment technologies, costs, and treatment
                      residuals disposal.

                      E. References
                        National Research Council (NRC). Safe
                      Water From Every Tap: Improving Water
                      Service to Small Communities. National
                      Academy Press. Washington, DC. 1997.
  USEPA. Office of Drinking Water.
Suggested Guidelines for Disposal of
Drinking Water Treatment Wastes Containing
Naturally-Occurring Radionuclides (July
1990 draft).
  USEPA. National Primary Drinking Water
Regulations; Radionuclides; Proposed Rule.
Federal Register. Vol. 56, No. 138, p. 33050.
July 18,1991.
  USEPA. Technologies and Costs for the
Removal of Radionuclides from Potable
Water Supplies. Prepared by Malcolm Pirnie,
Inc. July 1992.
  USEPA. Office of Ground Water and
Drinking Water. Suggested Guidelines for
Disposal of Drinking Water Treatment Wastes
Containing  Radioactivity (June 1994 draft).
  USEPA. Announcement of Small Systems
Compliance Technology Lists for Existing
National Primary Drinking Water Regulations
and Findings Concerning Variance
Technologies. Federal Register. Vol. 63, No.
151, p. 42032. August 6, 1998. (EPA 1998a).
  USEPA. "Small System Compliance
Technology List for the Non-Microbial
Contaminants Regulated Before 1996." EPA-
815-R-98-002. September 1998. (EPA
1998b).
  USEPA. "Actual Cost for Compliance with
the Safe Drinking Water Act Standard for
Radium-226 and Radium-228." Final Report.
Prepared by International Consultants, Inc.
July 1998. (EPA 1998c).
  USEPA Technologies and Costs for the
Removal of Radionuclides from Potable
Water Supplies. Draft. Prepared by
International Consultants, Inc. April, 1999.
(EPA 1999a).
  USEPA. "Small System Compliance
Technology List for the Radionuclides Rule."
Prepared by International Consultants, Inc.
Draft. April 1999. (EPA 1999b).
  USEPA. "Technical Support Document for
the Radionuclides Notice of Data
Availability." Draft. March, 2000. (EPA
2000a)

Appendix V—Economics and Impacts
Analysis

A. Overview of the Economic Analysis
1. Background
  Analysis  of the costs, benefits, and other
impacts of regulations is required under the
Safe Drinking Water Act Amendments  of
1996, Executive Order 12866 (Regulatory
Planning and Review), and EPA's internal
guidance for regulatory development. These

-------
                       Federal  Register/Vol.  65, No.  78/Friday,  April  21,  2000/Proposed  Rules
                                                                                 21621
 requirements are new relative to the 1991
 proposal for revisions to the existing National
 Primary Drinking Water Regulations
 (NPDWRs) forradionuclides.
   The actions that are anticipated to have
 regulatory impacts are evaluated in this •
 section. These actions are: (1) the correction
 the monitoring deficiency for combined
 radium-226 and radium-228; and (2) the
 establishment of a uranium NPDWR with an
 MCL of 20 ug/L; or (3) the establishment of
 a uranium NPDWR with an MCL of 40 ug/
 L; or (4) the establishment of a uranium
 NPDWR with an MCL of 80 ug/L. See
 "Combined Ra-226 and Ra-228" in the
 today's NODA (section III, part F) for a
 discussion of the monitoring corrections that
 will be finalized for the combined radium-
 226 and radium-228 ("combined radium")
 NPDWR. See "Uranium" in the NODA
 (section III, part H) for a discussion of the
 options being considered for finalization for
 the uranium NPDWR.
 2. Economic Analysis of the Regulatory-
 Actions Being Considered for Radionuclides
 in Drinking Water
  The economic analysis summarized here
 supports the finalization of the 1991
 Radionuclides proposal. The more detailed
 economic analysis (the Health Risk
 Reduction and Cost Analysis, EPA 2000b)
 may be obtained from the Water Docket, as
 described in the Introduction to today's
 NODA (see ADDRESSES). It provides central-
 tendency estimates of national costs and
 benefits and presents information on the data
 sources and analytic approaches used,
 including a qualitative discussion of the
 analytical limitations and uncertainties
 involved. Further uncertainty analyses will
 be performed to support the analyses
 summarized here and will be reported in the
 preamble to the final rule. It should be noted
 that these additional uncertainty analyses are
 not expected to alter regulatory decisions.
  The basic steps in a comprehensive
 economic analysis include: (1) Estimating
 baseline conditions in the absence of
 revisions to the regulations; (2) predicting
 actions that water systems will use to meet
 each regulatory option (the "decision tree");
 (3) estimating national costs resulting from
 compliance actions; (4) estimating national
 benefits resulting from compliance; and (5)
 assessing distributional impacts and equity
 concerns. In today's NODA, we present
 preliminary estimates of national costs and
 benefits for the options evaluated, focusing
 on monitoring and compliance costs and
 reductions in cancer risks. Other national
 costs and benefits (e.g., state administrative
 costs and risk reductions from incidental
 treatment of co-occurring contaminants) and
 potential distributional impacts are described
 qualitatively (see EPA 2000a and EPA
 2000b).
  The first step in the economic analysis,
 defining the analytical baseline, requires that
 water systems be apportioned into several
groups based on their predicted levels of
radionuclides and the current monitoring
scheme. In the case of the radionuclides
NPDWRs, this provides unusual challenges.
This is partly due to the fact that several
community water systems are not complying
with the existing regulations, which is
 reflected in the occurrence database used for
 this work (the National Inorganics and
 Radionuclides Survey, "NIRS'; see EPA 1991,
 proposed rule and EPA 2000a). Also, as
 discussed in the Introduction to  today's
 NODA, there are weaknesses in the current
 monitoring requirements that has lead to a
 situation in which some water systems
 having combined radium levels greater than
 the MCL of 5 pCi/L will not have knowledge
 of this fact (and hence are not presently in
 violation of the combined radium NPDWR).
 Both of these influences, the existing
 unresolved radionuclides NPDWR violations
 and the monitoring deficiencies, must be
 accounted for in the analytical baseline.
   The regulatory baseline and other
 analytical baselines are benchmarks to
 measure regulatory impacts against.
 Generating a national-level contaminant
 occurrence profile is an important part of this
 benchmarking process. The database used as
 the basis for this model, NIRS, is described
 in appendix I of today's NODA (Occurrence).
 The analysis of regulatory impacts uses this
 system-size stratified baseline occurrence
 model1 to estimate the percentages of water
 systems with contaminant levels within
 specified values (e.g.,  30 to 50% above the
 MCL). This information is then combined
 with other models to estimate the compliance
 costs and benefits associated with each
 option. Examples of models relevant to
 national costs estimation include "model
 systems2," compliance cost equations3, and
 the  compliance action prediction model or
 "decision trees4." Examples of models
 relevant to risk reduction and benefits
 estimation include the risk models described
 in appendix II and the risk reduction
 valuation models described in the Technical
 Support Document (EPA 2000a).
   The analytical baseline for combined
 radium reflects full compliance with the
  1 Tho NIRS database is stratified into four
categories: systems serving between 25—500
persons, 501—3,300 persons, 3,301-10,000 persons.
and 10.001-1,000,000 persons. Because of the small
sample size used to describe the larger systems, our
model uses only three categories: we combine the
two categories for systems serving greater than
3,301 persons into a single category.
  2 Model systems describe the universe of drinking
water systems by breaking it  down into discrete
"system size categories" by population served.
There are nine size categories: 25-100 persons
served; 101-500; 501-1,000; 1,001-3,300; 3,301-
10,000; 10,001-50,000; 50,001-100,000; 100,000-
1,000,000; > 1.000.000. Within each size category,
the systems arc described by a single set of "typical
characteristics" by source water typo (ground
versus surface water) and ownership type (public
versus private ownership). These characteristics
include the average and design flows and the
distribution of numbers of entry points per system.
  3 Unit compliance costs models include water
treatment cost models (e.g., W/W Cost and the
WATER model) and models for other compliance
options, like alternate water well sources and
purchasing water. For a discussion of the standard
EPA water treatment cost models, see EPA 1999d.
  •> Decision trees are models of the relative
probabilities that water systems will choose
particular compliance actions when in violation.
The probabilities are estimated based on
considerations of source water type, system size,
water quality, required removal efficiency, unit
costs, treatment issues fc.g., co-treatment and prc-
/post-treatment requirements), and residuals
disposal costs and issues:
 existing regulations as written, which have
 been fully enforceable since the 1986
 reauthorization of the SDWA. This approach
 assumes that, in the absence of any changes
 to the radionuclides NPDWRs, EPA and the
 States will eventually ensure that all systems
 fully comply with the existing regulations.
 This approach allows us to separate out the
 predicted number of systems with combined
 radium levels in excess of the MCL that have
 knowledge of the violation ("systems in
 violation") from the predicted number of
 systems that have levels in excess of the
 MCL, but that would not have knowledge of
 this under the current monitoring
 requirements. Since uranium is not currently
 regulated, no such corrections are necessary.
 It was also determined that treatment
 installed to remove the other radionuclides
 should not significantly impact the uranium
 analytical baseline.5

 B. Approach for Assessing Occurrence, Risks
 and Costs for Community Water Systems
   1. Assessing Occurrence
   To develop estimates of the baseline
 radionuclides occurrence profile for
 community water systems, we began by
 extrapolating from data obtained through
 EPA's National Inorganics and Radionuclides
 Survey (NIRS). This survey measured
 radionuclide concentrations at 990
 community ground water systems between
 1984 and 1986. For detailed information on
 the design of NIRS,  see Longtin 1988. For
 detailed information on how NIRS was used
 in this work, see the background documents
 (EPA 2000a and 2000b).
   We made adjustments to the NIRS data to
 address certain limitations, including (1) the
 small size of the sample of systems serving
 populations greater than 3,300 persons; (2)
 the decay of radium-224 prior to analysis of
 the NIRS water samples; (3) the need to
 convert mass measurements of uranium to
 activity levels; and,  (4) the lack of
 information on surface water systems. The
 analyses and discussions that follow
 concentrate on CWSs serving retail
 populations of less than one million persons.
 Discussions of preliminary and future
 economic impacts analyses of Non-Transient
 Non-Community Water Systems (NTSC
 systems) and the largest CWSs follow later in
 this section. The two occurrence approaches
 we examined are described next. For a
 discussion of the relative strengths and
 weaknesses of the two approaches to
 estimating occurrence, see the Technical
 Support Document (EPA 2000a).
  5 While the treatments installed to eliminate gross
alpha and combined radium may also reduce
uranium levels, we do not quantify these impacts
in this analysis. We make no adjustment for three
reasons. First, the NIRS data suggest that systems
with elevated levels of gross alpha or combined
radium rarely report uranium concentrations above
levels of concern. Second, some typos of treatment
used to remove gross alpha or radium are less
effective in removing uranium. Lastly, radium and
uranium occur at higher levels under very different
aquifer conditions: radium tends to occur at high
levels in water with low dissolved oxygon and high
total dissolved solids, while uranium occurs at
higher levels in oxygen-rich waters with low total
dissolved solids (sec the Technical Support
Document, EPA2000a).

-------
21622
Federal  Register/Vol. 65,  No.  78/Friday, April 21, 2000/Proposed Rules
2, "Direct Proportions Approach" to
Estimating Occurrence
  Because of uncertainties related to
extrapolating from the NIRS database to
national-level estimates, we applied two
approaches for estimating the national-level
central-tendency occurrence estimate. First,
we assumed that national occurrence is
directly proportional to the occurrence levels
measured in NiRS. For example, if the
radionuclide concentration in one percent of
the samples from NIRS representing a
particular water system size category are
greater than the MCL, we assumed that one
percent of all systems in that size class would
be out of compliance at the national level (It
is worth noting that using NIRS to
extrapolate to the State or regional level is
not valid, since NIRS was designed to be
representative at the national-level, but not at
these other levels). In cases where this
approach predicts "zero probability" of non-
compliance for a system size category (i.e., no
samples in NIRS were above the MCL being
considered), this approach is flawed, since
the expectation is that this finding actually
reflects a small probability, not "zero
probability." In other words, in situations
where "zero impact" is predicted, it is much
more likely that a very small number of water
systems will be impacted compared to true
"zero impact." For this reason, we also used
a mathematical model to simulate the
occurrence distribution, in which these "zero
probabilities" are replaced by estimated
small probabilities.
3. "Lognormal Model Approach" to
Estimating Occurrence
  The second approach recognizes that
"true" radionuclides occurrence will most
likely be spread over a range wider than that
observed in the survey. This approach
assumes that "probability plots" of the NIRS
data are lognormally distributed. A
probability plot compares the radionuclide
concentration for the various samples to the
probability of a given sample having that
level or less, where this probability is
estimated from the actual occurrence data
from NIRS. An assumption of lognormality
means that a probability plot for the
logarithms of the radionuclide levels would
be expected to be linear (fall on a straight
line).
  Inspection of the NIRS data suggests that
it is distributed in a roughly lognormal
                      pattern, with most systems reporting
                      concentration levels well below the MCLs of
                      concern. Several other studies also suggest
                      that the distribution of radionuclide
                      occurrence in drinking water systems is
                      likely to follow a lognormal distribution0, so
                      this assumption should be robust in most
                      cases. If the NIRS data were perfectly
                      lognormally distributed, both approaches
                      would lead to similar estimates of
                      occurrence. This is usually the case.
                      However, it should be noted that there
                      instances of significant deviations between
                      the two approaches. For example, the direct
                      proportions approach predicts that 0.4 % of
                      the systems serving more than 500 persons
                      will be impacted (61 systems) by an MCL of
                      20 pCi pCi/L for uranium, whereas the
                      lognormal model approach predicts that
                      1.8% of systems will be impacted (255
                      systems), amounting to a difference in
                      prediction of almost 200 impacted water
                      systems in this size category. There are
                      several possible explanations for this
                      deviation, but the important point is that the
                      use of both approaches allows the data gap
                      to be recognized and fully considered.
                        A statistical software package ("Stata") was
                      used to estimate a lognormal distribution that
                      best fits the data for systems in each size
                      class. We then used the fitted log means and
                      log standard deviations of the resulting
                      distributions to estimate the number of
                      systems out of compliance with each
                      regulatory option using standard statistical
                      equations. More detail regarding the
                      occurrence models and the estimation of the
                      numbers of impacted systems can be found
                      elsewhere (EPA 2000a and 2000b).
                      4. Assessing Risk
                        After determining the number of systems
                      out of compliance with each regulatory
                      option under consideration, we assessed the
                      risk reductions that would result from these
                      systems taking actions to come into
                      compliance. The approach for the risk
                      analysis begins with the development of
                      intrinsic "risk factors" for each group of
                      radionuclides. These risk factors are
                      composites that involve multiplying EPA's
                      best estimates of unit mortality and
                      morbidity cancer risk coefficients (risk per
                      pCi) for each group of radionuclides by
                      standard assumptions regarding drinking
                      water ingestion to determine the risk factors
                      associated with drinking water exposure (risk
per pCi/L). We then applied the individual
risk factors 7 to the estimates of the reduction
in exposure associated with each regulatory
change under consideration, taking into
account the population exposed. The
calculation of risk factors from risk
coefficients and a discussion of exposure
assumptions are detailed elsewhere (EPA
2000a). The risk factors (per pCi/L in
drinking water) used in the risk reduction
analyses are summarized in Table V-l.
  The unit8 risk factors applied in this
analysis refer to the aggregated small changes
in the probability of incurring cancer over a
large population. These unit probabilities can
be interpreted in two ways_:_ as the unit
lifetime excess probability of cancer
induction averaged over age and gender for
all individuals in a population or as the risk
for a statistically "averaged individual." It
should be noted that no one individual is
truly average, since the averaging also occurs
over gender. Given a model of radionuclide
occurrence, the population risks of excess
cancer incidence can be estimated before and
after a given regulatory option for the
individuals comprising the population, with
the difference being equal to the reduced
risk. These reductions in individual cancer
incidence probabilities may then be summed
over the population to indicate the central-
tendency number of "statistical cancer cases
avoided" annually. However, it should be
kept in mind that for many reasons,
including the large variance associated with
such risk factors, it is impossible to "check
this prediction" in any meaningful way. In
interpreting reduced risks for given options,
it is arguably best to think of them in terms
of reduced average "individual excess risk,"
rather than "cases avoided," for the reasons
just described. For example, it is much_easier
to understand the idea that an individual's
average lifetime risk of developing cancer
due to exposure to radionuclides in drinking
water has been reduced from three in ten
thousand to one in ten thousand for a
number of water systems under a given
option then to understand that an average of
0.5 cancer cases are avoided annually at the
national level for that option. The use of
"individual excess risk" avoids much the
confusion about "statistical cases," which are
conceptually difficult to understand.
   TABLE V-1.—AVERAGE INDIVIDUAL RISK FACTORS, AVERAGE WATER CONSUMPTION (1.1 L/PERSON/DAY) (PER PCI/L)
Regulatory option
Gross Alpha: changes In monitoring requirements (weighted average of Ra-224 and
Ra-226) 	
Gross Aloha: chanoes in MCL (Ra-224 onhrt 	
Morbidity
Lifetime in-
gestion
5.24E-06
4.77E-06
Annual in-
gestion
7.48E-08
6.81 E-08
Mortality
Lifetime in-
gestion
3.26E-06
2.90E-06
Annual in-
gestion
4.65E-08
4.15E-08
  *Sco the Technical Support Document (EPA
2000a) and the HRRCA (EPA ZOOOb).
  7 This analysis focuses on changes in cancer risks
from tap water ingcstlon. Individuals may be
exposed to radionuclides In drinking water through
other pathways (o.g,, inhalation while showering),
and uranium may have toxic effects on the kidneys;
however, we expect that any changes in these types
                      of risks will be, while not insignificant, much
                      smaller than the changes in cancer risks from
                      ingestion, and hence discuss them only
                      qualitatively in this analysis.
                        « "Unit risk factors and "unit risks" refer to the
                      risk per pCi/L in drinking water. They arc not
                      estimates of cancer incidence per se, but rather are
                      Indicators of the "potency" of a radionuclide. To
got estimates of the risks of cancer incidence for an
exposed population, the unit risk factors must be
used in conjunction with a radionuclide drinking
water occurrence model. These population risks
refer to the estimated numbers of excess statistical
cases of cancer that a population will face under a
given set of exposure assumptions.

-------
                       Federal Register/Vol.  65, No. 78/Friday,  April  21, 2000/Proposed Rules
                                                                              21623
   TABLE V-1.—AVERAGE INDIVIDUAL RISK FACTORS, AVERAGE WATER CONSUMPTION (1.1 L/PERSON/DAY) (PER PCI/L)—
                                                            Continued
Regulatory option
Combined Radium: changes in
226 and Ra-228) 	
Combined Radium: changes in I
Uranium: establish MCL (simple
monitoring requirements (weighted average of Ra-
J\CL (Ra-228 only) 	 	
average of U-234, U-235, and U-238) 	
Morbidity
Lifetime in-
gestion
2.30E-05
2.98E-05
1.95E-06
Annual in-
gestion
3.28E-07
4.26E-07
2.79E-08
Mortality
Lifetime in-
gestion
1 .63E-05
2.12E-05
1 .26E-06
Annual in-
gestion
2.32E-07
3.03E-07
1.81E-08
 5. Estimating Monetized Benefits
   In this section, we summarize the
 information used in estimating monetized
 benefits. A description of the methodology
 used for these estimates is found in the
 Technical Support Document (EPA 2000a),
 which provides background information on:
 (1) The economic concepts that provide the
 foundation for benefits valuation; (2) the
 methods that are typically used by
 economists to value risk reductions, such as
 wage-risk, cost of illness, and contingent
 valuation studies; (3) the approach for
 valuing the reductions in fatal cancer risks
 and nonfatal cancer risks; (4) the use of these
 techniques to estimate the value of the risk
 reductions attributable to the regulatory
 options for radiomiclides in drinking water;
 and (5) the limitations and uncertainties
 involved in the estimation. For more detail
 on the methodology employed, see the
 Health Risk Reduction and Cost Analysis
 (HRRCA, EPA 2000b).
   This benefits analysis is based on two basic
 types of valuation: fatal cancer risk
 reductions and non-fatal cancer risk
 reductions. Fatal cancer risk reductions are
 valued in terms of the "value of a statistical
 life" (VSL), which does not refer to the value
 of an identifiable individual, but rather refers
 to the value of small reductions in mortality
 risks over a large population. For example,
 let us assume that a regulatory option results
 in a risk reduction of "one statistical fatal
 cancer case." This refers to the summation of
 small risk reductions over a large number of
 persons such that the summation equals "one
 case" (say, one hundred thousand persons
 each face a risk reduction of 1/100,000).
 Using our methodology, the resulting benefits
 would be equal to "one statistical life."
 Continuing the example, if each person were
 willing to pay $20 for such a risk reduction
 (1/100,000), the resulting VSL would be S2
 million (S20 times 100,000 persons).
 However, since there is no direct information
 on what persons are willing to pay for the
 risks we are interested in, we must use
 indirect methods for estimating the VSL. The
 currently accepted methodology involves
 transferring the VSL from studies of the wage
 increases that persons "demand" in exchange
 for accepting jobs with slightly higher
 chances of accidental fatality ("wage-risk
 studies"). There are a number of assumptions
 involved in making this transfer, which are
 discussed in more detail in the background
 documentation (EPA 2000a and 2000b).
  Valuing nonfatal cancer risk reductions is
often done  with "cost of illness studies,"
which examine the actual direct (e.g.,
 medical expenses) and indirect (e.g., lost
 work or leisure time) costs incurred by
 affected individuals. Unfortunately, this
 valuation does not measure the "willingness
 to pay" to avoid nonfatal cancers, but rather
 assumes that benefits are equal to the
 avoided costs. The studies used and
 assumptions involved are discussed
 elsewhere (EPA 2000a and 2000b).
   Because of the uncertainties involved in
 valuations, we used an estimate of the range
 of values of reductions in fatal and non-fatal
 risks attributable to the radionuclides
 regulations using the following estimates
 (1998 dollars):
   Fatal Risk Reduction Valuations ("Value of
 a Statistical Life", VSL):
   Best Estimate: Value of fatal risk reductions
 = Statistical lives saved * S5.9 million per
 statistical life.
   Low End Estimate: Value of fatal risk
 reductions = Statistical lives saved * SI.5
 million per statistical life.
   High End Estimate: Value of fatal risk
 reductions = Statistical lives saved * 511.5
 million per statistical life.
   Non-Fatal Risk Reduction Valuations
   Best Estimate: Value of nonfatal risk
 reductions (medical costs only) = Statistical
 cases averted * S0.10 million.
   Low End Estimate: Value of nonfatal risk
 reductions (medical costs only) = Statistical
 cases averted * $0.09 million.
   High End Estimate: Value of nonfatal risk
 reductions (medical costs only) = Statistical
 cases averted *- SO.ll million.
 6. Estimating the Costs of Compliance
   The last component of the analysis
 involves estimating the costs of compliance
 for each regulatory option. The options under
 consideration will increase the costs of
 monitoring for all regulated systems, as well
 as require a small fraction of the systems to
 take action to reduce the contaminant levels
 in their finished water to achieve
 compliance. Examples of compliance actions
 include installing treatment, purchasing
 water from another system, changing the
 water source used (e.g., installing a new
 well), blending the contaminated water with
 other source water that is below the MCL,
 and, in cases where the contaminated well is
 not essential to meet capacity, stopping
 production from the contaminated well. The
 cost analysis models both new capital costs
 and, and when appropriate, incremental
 operations and maintenance costs for this
variety of compliance options.  The inputs
used in the cost analysis and a comparison
of the modeled costs for treatment, alternate
source, purchased water to case studies can
 be found in the Technical Support Document
 (EPA 2000a) and elsewhere (EPA 1998a).

 C. Summary of Annual Costs and Benefits

 1. Estimates of Costs and Benefits for
 Community Water Systems
   The following results reflect the regulatory
 options that are currently being considered.
 Results for the other options that were
 analyzed (correction of monitoring
 deficiencies for gross alpha and changes to
 MCLs for gross alpha and Ra-228), but that
 EPA does not plan to adopt, are located in
 the Technical Support Document (EPA
 2000a). In addition to EPA's preferred
 options, we have included all results in the
 Technical Support Document to allow
 interested stakeholders to comment on these
 other options, if desired.
   Table V—2 shows the summarized results
 for EPA's analysis of risk reductions, benefits
 valuations, and costs of compliance (see EPA
 2000b for a break-down of the summary by
 water system size). The risk reductions and
 cost estimates are based on the estimated
 range of numbers of community water
 systems predicted to be out of compliance
 with each of the regulatory options assessed.
 The ranges shown reflect the two occurrence
 model methodologies previously described,
 the "direct proportions" and "lognormal
 model" approaches. The ranges in
 occurrence predictions necessarily result in
 ranges of estimates for risk reductions,
 benefits valuations, and compliance costs.
 There are two ranges shown for values of
 cancer cases avoided, the "best-estimate
 range,"  based on the best-estimate of risk
 reduction valuations, and the "low/high-
 estimate range," which reflects the use of the
 two occurrence models and the uncertainty
 in the risk reduction valuations ("low-end"
 versus "high-end" estimates). These ranges
 do not reflect uncertainty in other model
 inputs, like risk factors in the case of risk
 reduction estimates and treatment unit costs
 in the case of compliance costs. Quantitative
 uncertainty analyses for risk reductions,
 benefits, and compliance costs will be
 conducted and reported in the preamble to
 the final rule. EPA expects that these
 uncertainty analyses will not impact final
 decisions.
  Eliminating the  combined radium-226/-228
monitoring deficiency9 is predicted to lead
to 210 to 250 systems out of compliance with
an MCL of 5 ng/L, affecting 33,000 to 460,000
  0 The monitoring deficiency will be corrected by
requiring the separate analysis of Ra-228 for
systems with gross alpha levels below 5 pCi/L.

-------
21624
Federal  Register/Vol. 65,  No.  78/Friday, April 21, 1000/Proposed Rules
persons. Implementing an MCL of 20 ug/L for
uranium is predicted to impact 830 to 970
systems, affecting 470,000 to 2,100,000
persons. An MCL for uranium of 40 ug/L is
predicted to impact 300 to 430 systems,
affecting 47,000 to 850,000 persons; 80 ug/L
is predicted to impact 40 to 170 systems,
affecting 7,000 to 170,000 persons. These
estimates for uranium are based on the
assumption that the activity-to-mass ratio in
drinking water is 1:1. EPA's current best-
estimate for the average activity-to-mass ratio
for the various uranium isotopes in drinking
water is 0.9. EPA will update this assumption
for the uranium options in the Regulatory
Impact Assessment supporting the rule
finalization. However, the impact is expected
to be small. For example, using the lognormal
occurrence distribution model for the 40 ug/
L option, an assumption of an activity-to-
raass ratio of 0.9 results in an estimated
number of impacted systems of 370, a
decrease of only 12-13%.
  The estimated risk reduction range for the
option addressing the combined radium
monitoring deficiency is 0.3 to 0.5 cancer
cases avoided annually, with an associated
annual monetized benefits range of one to
two million dollars. The risk reductions
estimated for the uranium options range from
0.2 to 2 cases avoided annually for an MCL
of 20 mg/L, 0.04 to 1.5 cases avoided
annually for an MCL of 40 ug/L, and 0.01 to
1 case avoided annually for an MCL of 80 ug/
                      L. The associated annual monetized benefits
                      for the uranium options range from 0.6 to 8
                      million dollars (20 mg/L), 0.1 to 6 million
                      dollars (40 ug/L), and less than  0.1 to 4
                      million dollars (80 ug/L).
                        Annual compliance costs range from 20 to
                      30 million dollars for the option addressing
                      the combined radium monitoring
                      deficiencies. Annual compliance costs for the
                      uranium options range from 30  to 140
                      million dollars for an MCL of 20 mg/L, 6 to
                      60 million dollars for an MCL of 40 ug/L, and
                      5 to 30 million dollars for an MCL of 80 ug/
                      L.
                        As demonstrated by this analysis the
                      estimated range of central-tendency annual
                      compliance costs exceed the ranges of
                      central-tendency annual monetized benefits
                      for all options. This is not surprising given
                      that most of the systems impacted are small
                      water systems, which tend to have much
                      higher per customer compliance costs
                      relative to large systems, while  the per
                      customer risk reduction is independent of
                      water system size. Except in cases where risk
                      reductions are quite large, it is predictable
                      that estimated annual costs will outweigh
                      estimated annual benefits for small water
                      systems (given -the current methodologies for
                      estimating benefits). However, it should be
                      pointed out that all of the regulatory options
                      being considered have associated lifetime
                      morbidity risks near or in excess of one in
                      ten thousand, which is the upper bound on
the preferred risk range according to EPA's
policies on regulating drinking water
contaminants. In the case of uranium, it is
also important to recognize that there may be
considerable non-quantified (not
monetizable) benefits associated with
reductions in kidney toxicity risks. If such
benefits were quantified, it is likely that the
net benefits would be more favorable for all
uranium options.
  Some commenters may argue that costs
and benefits considerations should lead to
the conclusion that the finalization of the
correction of the combined radium
monitoring deficiencies and/or the
establishment of a NPDWR for uranium are
not warranted. However, this conclusion
would lead to a  situation where customers of
many ground water systems face lifetime
morbidity risks greatly in excess of the
acceptable risk upper limit of one in ten
thousand. According to EPA's policies, the
proper use of this flexibility should lead to
regulatory decisions that have associated
risks that are within or acceptably close to
EPA's longstanding goals of limiting excess
lifetime morbidity risks to the range of one
in a million to one in ten thousand, except
under unusual circumstances.  EPA solicits
comment on this interpretation of costs and
benefits for the finalization of the 1991
radionuclides proposal.
BILLING CODE 6560-SO-U

-------
                 Federal Register/Vol. 65, No. 78/Friday, April 21, 2000/Proposed Rules
21625

•' >
OS.
^^
H
j
^]
O
a:
Ed
H
^*
OS
a
IB
u
<
a.
Ed
a
i° jb
f- ""•
fit fa,
en jg-
S O
w £

W 03 a
>• >• S
Table
MUNITY WATERS
i BEING CONSIDE)
S£
MEFITS FOR CO
OPTIOl
H
es
c
z:
C/3
E™"
c/5
o
u
tb
0
>•
C£
<

5

CO








..
es
i
•a
• a
C3
<5
M
. i
25
•3
OS
•3
C
15
S
o
c
: «£
deficiencies
e*
s
•£
o
e.
arrcctions to the moi
o
.& •
•a
u
u
s.
j •-
o
.0
6
i
«
"5
2
c.
en
S
u
I




en
C
•— S =; •JT
o c s S
i,- s ^
= p" •? 2r
•OT B M. *^y
^ e> to t_
*** Q. tS o
o •
. . o
e« ' .
"*o ^ • '•'•;
t» — ^f:
£ S -"•"§•"'
e& . y-^. 5> ^_^
^" tS- ^ ^j fl
*J' ^!". ^a *H j
C ' *^ ' *^*" ' i»~ *™
11 ° 1 '
o/' o ' ^*jTj
' •••, '' • • . . ''•
• • — ''• Ji^ ':
£ $'! s
ft- U s a
O j_ < ft
Hit
« Q^y o >— '
P* jrj
^


^Estimated IJfe; time
:•. .E^ces$:eancei:; ...
;;Mprbidity:Riskat
fe^Mcfefe,^

i>eirs'<[f%stems :
[mpSctedJ ;.:;=, v.
ilatibji Exposed:-:
bM&Mi^B!
•3. S* r+
E




"o*-
c
0



-




<
c








•*
01
c




o o
1 1
o c





X

(fl
in S
•*- e>









TT OO
M —
0 °
V V,




?^
— O
o o
0 O
^**




X

• 170 systems
170 K persons)
O i
•» r-.



o
OO.
J
U
Q.
O
00

S
n
c ^2
£ ~Sa

•O vt
e£ ^f 2 S
- - £_} C 5
*4> ^f C^ 0> »
OO "~ l. O ™
S ^"^ | =
C"* *•- o o "^
^ O — o

S l^o -2 -^
1 « § | 5s
I jj|s ||
fe = S^ -S
^5 S S H £ —
H r ~ "S !P >•
3 "«-J §| ,2J « "« Q
!§ll-l U
| =? | S s ,§1
1 1 *il li
'S ' i g 2 i •=
= •- '= A °J ^ §
S - P (S 2 -a ^
I 1 J-gf ^ 22
OE2-c^S f°
S "0 fN *- O ^ ""
|i.I .C -S ™ T **
•••^. C " D. O •^
sr »- = §• si
0 g -S § -2 S .§ E
Jjgg-ogg> g»
y ' s i S 1 f il"
-5, g ° § 3 J •£ "o
§""s -§ — -=§"§ §§"
— « rt S " " .SJ V. *~ *^u
I. I III! 1 1 Hi
i"§ i lllf i sf 1
'ifiliifi i1!
| S J § -jl g 2 |j. S«g
•^ "J = Sgl^-S 5=|
— = S ° §"— 2 "fi € -f §
o*S w MC-«>n'2 S2"^
|"J J JoJU | 1JS
I i §• s ^ -| s ;| 1,-g if

3 OT •c'iooS-s^sMar
ja c-2 SB.S^ g S>^5
S.O X^<-*li;S™.S^=~l
1^ ~ riill^«=II
BILLING CODE 6560-50-C

-------
21626
Federal  Register/Vol. 65, No. 78/Friday,  April  21,  2000/Proposed Rules
2. Uncertainties in the Estimates of Benefits
and Costs
  The models used to estimate costs and
benefits related to regulatory measures have
uncertainty associated with the model
inputs. The types and uncertainties of the
various inputs and the uncertainty analyses
for risks, benefits, and costs are qualitatively
discussed later in this section.
  a. Uncertainties in Risk Reduction
Estimates. For each individual radionuclide,
EPA developed a central-tendency risk
coefficient that expresses the estimated
probability that cancer will result in an
exposed individual per unit of radionuclide
activity (e.g., per pCi/L) over the individual's
lifetime (assumed to be 70 years). Two types
of risks are considered, cancer morbidity,
which refers to any incidence of cancer (fatal
or non-fatal), and cancer mortality, which
refers to a fatal cancer illness. For this
analysis, we used the draft September 1999
risk coefficients developed as part of EPA's
revisions to Federal Guidance Report 13
(FGR-13, EPA 1999e). FGR-13 compiled the
results of several models predicting the
cancer risks associated with radioactivity.
The cancer sites considered in these models
include the esophagus, stomach, colon, liver,
lung, bone, skin, breast, ovary, bladder,
kidney, thyroid, red marrow (leukemia), as
well as residual impacts on all remaining
cancer sites combined.
  There are substantial uncertainties
associated with the risk coefficients in FGR-
13  (EPA 1999e): researchers estimate that
some of the coefficients may change by a
factor of more than 10 if plausible alternative
models are used to predict risks. While the
report does not bound the uncertainty for all
radionuclides, it estimates that the central-
tendency risk coefficients for uranium-234
and radium-226 may change by a factor of
seven depending on the models employed to
estimate risk.10 Ranges that reflect
uncertainty and variability in the risk
coefficients will be used in a Monte Carlo
analysis of risk reductions and benefits, the
results of which will be reported in the
preamble to the final rule.
  In addition, as previously described in
appendix I, "Occurrence," the available
occurrence data do not provide information
on the contribution of individual
radionuclides or isotopes to the total
concentrations of gross alpha  or uranium.
Therefore, there is  uncertainty involved in
the assumptions about which radionuclides
comprise the reported gross alpha or uranium
activity. These and other uncertainties
related to occurrence information (e.g.,
uncertainty in extending the NIRS database
results to the national level) will also be
incorporated in a Monte Carlo analysis of
benefits to estimate the range  of uncertainty
surrounding the central-tendency estimates.
Other inputs that will be used in the Monte
Carlo analysis of benefits are the age- and
gender-dependent distributions of water
ingestion, which are  used in estimating
lifetime exposure, and the credible range for
the "value of a statistical life." This
                      uncertainty analysis is not expected to alter
                      the regulatory options discussed in today's
                      NODA.
                        b. Effects of the Inclusion of a Latency
                      Period and Other Factors on the Estimate of
                      Benefits. The expected analytical impacts of
                      the inclusion of other factors, e.g., a cancer-
                      latency period, cancer premiums, and non-
                      quantifiable benefits have been discussed in
                      the recent radon proposed NPDWR (64 FR
                      59295). The relevant points are summarized
                      briefly here and in more detail in the
                      Technical Support Document for the
                      Radionuclides NODA (USEPA 2000a).
                        There are several potentially important
                      sources of uncertainty related to the
                      valuations of risk reductions for the
                      regulatory options examined. Since the
                      mortality valuations dominate the estimated
                      benefits, factors that affect the VSL are most
                      important. Factors that may affect the VSL
                      include discounting due to cancer latency
                      periods,11 cancer-related premiums that may
                      raise the value of statistical life, and other
                      currently non-quantifiable benefits. Cancer
                      latency-related discounting would be
                      expected to decrease the present VSL, while
                      cancer premiums would tend to increase the
                      present VSL. It is not clear whether an
                      inclusion of all of these factors would be
                      expected to result in a lower or higher
                      present VSL. However, EPA is currently
                      working  with the Science Advisory Board
                      (SAB) to determine how to best include these
                      factors, whether the inclusion is quantitative
                      or qualitative.
                        c. Uncertainty in Compliance Cost
                      Estimates. Regarding uncertainty in the
                      compliance cost estimates, these estimates
                      assume that most systems will install
                      treatment to comply with the MCLs, while
                      recent research suggests that water systems
                      usually select compliance options like
                      blending (combining water from multiple
                      sources), developing new ground water
                      wells, and purchasing water (EPA 1998a and
                      c, EPA 2000a). Preliminary data (202
                      compliance actions from 14 States) on nitrate
                      violations suggest that only around a quarter
                      (25%) of those systems talking action in
                      response to a nitrate violation installed
                      treatment, while roughly a third developed a
                      new well or wells. The remainder either
                      modified the existing operations (10—15%),
                      blended  (15%), or purchased water (15—
                      20%). Similar data for radium violations
                      from the State of Illinois (77 compliance
                      actions) indicate that around a quarter of
                      systems taking action installed treatment,
                      while the majority (50—55%) purchased
                      water, with the remainder (20-25%) either
  '"Table 2.4. Uncertainty Categories for Selected
Risk Coefficients Federal Guidance Report 13
(1999).
                        " A latency period refers to the average amount
                      of time that passes between the beginning of
                      exposure to a carcinogen or multiple carcinogens
                      and the on-set of fatal cancer. There is considerable
                      uncertainty in estimating a "typical latency period"
                      for the options studies here for many reasons,
                      including the large rangcsin estimated latency
                      periods for given cancer types and the large
                      uncertainty involved in predicting which type or
                      types of cancer will result from exposure to a given
                      radionuclide in drinking water. It is also uncertain
                      what discounting rate would be appropriate in this
                      situation. Some may argue that discounting is
                      entirely inappropriate (a rate of zero) and others
                      may argue that typical financial discount rates arc
                      appropriate (3 to 7%).  .
installing a new well, blending, or stopping
production from the contaminated well or
wells. The prevalence of the use of these non-
treatment options is a cross-cutting issue for
future Regulatory Impact Assessments and
probably will not be resolved before the
radionuclides NPDWR is finalized. EPA is
following up with this study and will report
the results at a later date.
  While these "other than treatment" options
may cost as much as or more than treatment
in some cases, they are expected to be less
expensive on average, which largely explains
their prevalence as compliance options. For
example, EPA has recently estimated  the
costs associated with developing municipal
wells to range from S0.08/kgal to S0.46/kgal,
depending on system size, geologic setting,
and other site specific parameters (EPA
1999b), with an average of S0.23/kgal for
systems serving between 501 and 1,000
persons and S0.17/kgal for systems serving
between 10,001 and 50,000 persons.12 These
costs include testing and drilling, steel
casings with cement lining, pumps,
including electrical connections and
controls, and a pump shelter. For smaller,
non-municipal PWS systems, we estimate
that wells could cost from 10 to 80 percent
of the costs presented for municipal systems.
As shown in the Technical Support
Document (EPA 2000a), these production
costs are much lower than those for typical
treatment, especially for small systems.
When feasible, selection of such options may
reduce compliance costs significantly. The
Technical Support Document includes data
on other non-treatment options like
purchasing water and blending.
  Preliminary uncertainty analyses suggest
that variability in the unit compliance costs
and decision tree assumptions dominate the
over-all cost variability. To evaluate the
potential variability in the compliance cost
estimates, a Monte Carlo analysis will
support the Regulatory Impact Assessment
for the final rule. Inputs that influence cost
variability include:
  • Numbers of total systems in the various
system size categories.
  • Distributions of entry points per system
in the various system size categories.
  » Distributions of populations served by
size category.
  • Flow sizes as a function of population
served.
  • Daily household water consumption.
  • Proportions of systems and sources
exceeding regulatory limits.
  • Unit costs (capital and O&M) of
treatment technologies and annual costs of
alternate source and regionalization.
  • Proportions of non-compliant systems
choosing between treatment, alternate source,
and regionalization.
  Since per system costs are much higher for
very large systems, the assumptions used in
the larger water system size categories can be
expected to dominate the variability in
national costs. Each of these inputs will be
modeled using probability distributions that
  12 This estimate is based on total capital costs
ranging from approximately $135,000 to 3550,000
per MGD of flow. The estimate assumes typical
relationships betivcen design and average daily
flows and a capital discount rate of 3 or 7%.

-------
                      Federal Register/Vol. 65,  No.  78/Friday, April 21,  2000/Proposed  Rules
                                                                            21627
 reflect the state of the available data. In some
 cases, input variability will be estimated
 from SDWIS, the CWSS, or other sources
 (e.g., distributions of populations served,
 daily household water consumption, unit
 costs) . In other cases, input variability will
 have to be based on best professional
 judgement. Again, this uncertainty study is
 expected to provide useful information, but
 is not expected to result in changes to the
 regulatory decisions described in today's
 NODA.
 D. Estimates of Costs and Benefits for Non-
 Transient Non-Community Water Systems
   The available data are not sufficient to
 allow EPA to predict a central-tendency
 impact of the regulatory options on non-
 transient non-community water systems
 (NTSC systems). Instead, EPA conducted a
 "what-if" analysis of potential costs and
 benefits based on reasonable assumptions of
 the percentage of NTSC systems impacted by
 the various options (EPA 2000b). A "what-if
 analysis allows us to pose hypothetical
 occurrence scenarios and to estimate costs
 and benefits for these scenarios. If the
 scenarios are chosen properly, they should
 bound the reasonable set of potential costs
 and benefits for NTSC systems. However, the
 estimates should not be interpreted as
 representing "best estimates," which would
 be based on an occurrence survey of
 radionuclides occurring at NTSC systems.
 The Technical Support Document (EPA
 2000a) provides details on the inputs and
 assumptions used for estimating regulatory
 impacts for NTSC systems. The resulting
 estimates of the percentage of systems out of
 compliance are provided in Table V-3.
   TABLE V-3.—ASSUMPTIONS FOR HYPOTHETICAL "WHAT-IF" ANALYSIS FOR NON-TRANSIENT NON-COMMUNITY WATER
                                 SYSTEMS (APPROXIMATELY 19,300 SYSTEMS NATIONWIDE)
Regulatory option
Gross Alpha at 15 pCi/L 	 ..
Combined Radium at 5 pCi/L 	
Uranium at 20 pCi/L:
Ground water 	
Surface water 	 	 	 	
Percent of na-
tional systems
in states with
elevated levels
(1) (percent)
60
79
54
29
Upper bound:
10% of col. (1)
(percent)



3
Lower bound:
1% of col. (1)
(percent)



0
   We calculated risk reductions associated
 with each set of assumptions using the same
 analytic approach as outlined for the
 community water systems. However, we use
 lower water intake assumptions because the
 population affected generally is not at the
 location served full-time or year-round. The
 risk factors were estimated using the same
 risk coefficients as a starting point (risk per
 pCi), but use different water consumption
 assumptions to calculate lifetime excess risk
 factors (risk per pCi/L). A cost model is used
 to predict the annual compliance costs for
 these systems based on their size classes
 (EPA 2000); in general, non-transient non-
 community systems tend to use ground water
 and serve small populations.
   The results of the analysis are summarized
 in Table V-4. If EPA requires non-transient
 non-community systems to comply with the
 gross alpha standard of 15 pCi/L, under the
 assumptions used in the analysis the number
 of systems out of compliance could range
 from 110 to 1,100 systems. The associated
 annual costs range from SI million to S4
 million and the statistical cancer cases (fatal
 and nonfatal) avoided annually range from
 0.01 cases to 0.1 cases. For combined radium,
 the resulting number of impacted systems
 ranges from 150 to 1,500 systems with annual
 costs ranging from $1 million to S6 million
 and an associated number of annual
 statistical cancer cases avoided ranging from
 0.02 cases to 0.2 cases. For a uranium MCL
 of 20 ug/L, the results suggest a range of
 impacted ground water systems from 100 up
 to 1,000 systems with annual costs ranging
 from SI million to $4 million and an
 associated number of annual statistical
 cancer cases avoided ranging from less than
 0.01 cases up to 0.04 cases. The resulting
 number of surface water systems impacted by
 a uranium MCL of 20 ug/L ranges from less
 than 10 to less than 20 systems. The
 associated national annual costs for surface
 water systems is less than SO.l million up to
 0.1 million with annual risk reductions of
 less than 0.01 statistical cancer cases.
        TABLE V-4.—HYPOTHETICAL "WHAT-IF" RESULTS FOR NON-TRANSIENT NON-COMMUNITY WATER SYSTEMS
Regulatory option

Gross Alpha at 15 pCi/L 	
Combined Radium at 5 pCi/L 	
Uranium at 20 pCi/L:
Ground water 	 	 	
Surface water 	
Lower Bound Estimate
Number of
systems out
of compli-
ance
110
150
100
<10
Annual costs
(million
dollars)
1
1
1
0.03
Statistical
cancer cases
avoided
(cases)
0.01
0.02
<0.01
<0.01
Upper Bound Estimate
Number of
systems out
of compli-
ance
1,100
1,500
1,000
<20
Annual costs
(million
dollars)
4
6
4
0.1
Statistical can-
cer cases
avoided
0.1
0.2
0.04
<0.01
  Note: These results are based on hypothetical assumptions regarding the percent of systems likely to be out of compliance with each requ-
latory option as discussed in the preceding text. These are not estimates of actual compliance costs or risk reductions, and are provided for illus-
E. Impacts for Systems Serving Greater Than
One Million Persons
  Based on an Internet search of the available
water quality information for water systems
serving greater than one million persons
(very large systems), there is no direct
evidence that closing the monitoring
deficiencies for radium will impact these
systems. However, the internet search was
not conclusive in ruling out the possibility
that one or more systems serving greater than
one million persons would be impacted by
these options. For this reason, EPA has
followed up with the few systems in question
to determine the likelihood of impact. The
follow-up confirmed that there were no
impacts expected for these systems. Uranium
occurrence data for these systems was
collected to the extent feasible and there is
no evidence of an impact at 20 or 40 ug/L.

-------
21628
Federal Register/Vol. 65,  No. 78/Friday, April 21, 2000/Proposed  Rules
F. References
Longtin, J.P. "Occurrence of Radon, Radium,
  and Uranium in Groundwater." JAWWA.
  Vol. 80, No. 7, pp. 84-93. July 1988.
National Research Council. Risk Assessment
  of Radon in Drinking Water. National
  Academy Press. Washington, DC. 1999.
  (NAS 1999).
USEPA. National Primary Drinking Water
  Regulations; Radionuclides; Proposed
  Rule. Federal Register. Vol. 56, No. 138, p.
  33050. July 18,1991.
USEPA. "Actual Cost for Compliance with
  the Safe Drinking Water Act Standard for
  Radium-226 and Radium-228—Final
  Report." Prepared by International
  Consultants, Inc. for the Office of Ground
  Water and Drinking Water. Draft. July
  1998. (EPA 1998a)
USEPA. "Evaluation of Full-Scale Treatment
  Technologies at Small Drinking Water
  Systems: Summary of Available Cost and
  Performance Data." Prepared by ICF, Inc.
                       and ISSI, Inc. for the Office of Ground
                       Water and Drinking Water. December 10,
                       1998. (EPA 1998b)
                     USEPA. Results from survey of compliance
                       actions taken in the State of Illinois in
                       response to the NPDWR for combined
                       radium. Submitted from EPA Region 5.
                       1998. (EPA 1998c)
                     USEPA. "Guidelines for Preparing Economic
                       Analysis." Review Draft. November 3,
                       1998. (EPA 1998d)
                     USEPA. "Regional Variation of the Cost of
                       Drinking Water Wells for Public Water
                       Supplies." Prepared by Cadmus for the
                       Office of Ground Water and Drinking
                       Water. Draft. October 1999. (EPA 1999b)
                     USEPA. "Drinking Water Baseline Handbook:
                       First Edition." Draft dated March 2,1999.
                       (EPA 1999c)
                     USEPA. "Evaluation of Central Treatment
                       Options as Small System  Treatment
                       Technologies." Prepared by SAIC for EPA.
                       Draft dated January 28,1999. (EPA 1999d)
USEPA. Cancer Risk Coefficients for
  Environmental Exposure to Radionuclides,
  Federal Guidance Report No. 13. US
  Environmental Protection Agency,
  Washington, DC, 1999. (EPA 1999e)
USEPA. "Technical Support Document for
  the Radionuclides Notice of Data
  Availability." Draft. March, 2000. (EPA
  2000a)
USEPA. "Preliminary Health Risk Reduction
  and Cost Analysis: Revised National
  Primary Drinking Water Standards for
  Radionuclides." Prepared by Industrial
  Economics, Inc. for the Office of Ground
  Water and Drinking Water. Draft. January
  2000. (EPA 2000b)
  Dated: April 7, 2000.
Charles J. Fox,
Assistant Administrator, Office of Water.
[FR Doc. 00-9654 Filed 4-20-00; 8:45 am]
BILLING CODE 6560-50-U

-------