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
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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
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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.
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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
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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
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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.
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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).
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Federal Register/Vol. 65, No. 78/Friday, April 21, 2000/Proposed Rules
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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
.
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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
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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)
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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.
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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
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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.
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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.
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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.
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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
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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
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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).
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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:
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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.
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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.
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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
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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
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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
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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
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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).
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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
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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
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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.
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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.
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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).
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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.
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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
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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).
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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.
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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.
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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
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Federal Register/Vol. 65, No. 78/Friday, April 21, 2000/Proposed Rules
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BILLING CODE 6560-50-C
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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%.
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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.
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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
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