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

ENVIRONMENTAL PROTECTION

AGENCY

40 CFR Parts 141 and 142

[FRL–6580–8]

RIN–2040–AC98

National Primary Drinking Water

Regulations; Radionuclides; Notice of

Data Availability

AGENCY: Environmental Protection

Agency.

ACTION: Notice of data availability for

proposed rules with 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 owdocket@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 Examples of regulated

entities

Industry ................. Privately-owned CWSs

and NTNCWSs.

State, Tribal, and

Local Governments.

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

be 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, NonCommunity 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 owdocket@epamail.epa.gov. Electronic

comments must be submitted as a

WordPerfect 8.0 or ASCII file avoiding

the use of special characters and forms

of encryption and must be transmitted

by midnight June 20, 2000. Electronic

comments must be identified by the

docket name, number, or title of the

Federal Register. Comments and data

also will be accepted on disks in

WordPerfect 8.0 or in ASCII file format.

Electronic comments on this document

may be filed online at many Federal

Depository Libraries.

Abbreviations and Acronyms Used in

This Notice

Organizations

APHA—American Public Health Association

ASTM—American Society for Testing and

Materials

AWWA—American Water Works Association

ICRP—International Commission on

Radiological Protection

NBS—National Bureau of Standards

NSF—National Sanitation Foundation

ANPRM—Advanced Notices of Proposed

Rulemaking

ATSDR—Agency for Toxic Substances and

Disease Registry

BNL—Brookhaven National Laboratory

CFR—Code of Federal Regulations

EML—Environmental Measurements

Laboratory

ERAMS—Environmental Radiation Ambient

Monitoring System

ERD—Environmental Radiation Data

ERIC—Educational Resources Information

Center

FGR–13—Federal Guidance Report 13

FR—Federal Register

FRC—Federal Radiation Council

NAS—National Academy of Sciences

NCHS—National Center for Health Statistics

NESHAP—National Emissions Standards for

Hazardous Air Pollutants

NIRS—National Inorganic and Radionuclide

Survey

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

NIST—National Institute of Standards and

Technology

NODA—Notice of Data Availability

NPDES—National Pollutant Discharge

Elimination System

NPDWRs—National Primary Drinking Water

Regulations

NRC—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

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 liter

mg/kg/day—milligram per kilogram per day

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

μCi—microCurie

μCi/kg—microCurie per kilogram

μg or ug—microgram

μg/g or ug/g—microgram per gram

μg/L or ug/L—microgram per liter

μg uranium/L—microgram uranium per liter

μg uranium/kg/day—microgram uranium per

kilogram per day

μR/hr—micro Roentgen per hour

μSv/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/μg—picoCurie per microgram

Other Terms

ACA—anticentromere antigen

ALP—alkaline phosphatase

AS—alpha spectrometry

BAT—best available treatment

BEIR—biological effects of ionizing radiation

BMG—β2-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-β-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 NonCommunity 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 I–1 summarizes the major

elements of the 1976 rule, the 1991

proposal and the issues being

considered in today’s NODA.

21578 Federal Register / Vol. 65, No. 78 / Friday, April 21, 2000 / Proposed Rules

TABLE I–1.—COMPARISON OF THE 1976 RULE, 1991 PROPOSAL, AND 2000 NODA

Provision 1976 Rule (Current Rule) 1991 Proposal 2000 NODA

Affected Systems CWS ...................................................... CWS + NTNC ....................................... CWS + several NTNC options based

on the 1991 proposal.

MCLG ................... no MCLG ............................................... MCLG of zero ........................................ MCLG of zero.

Radium MCL ........ Combined Ra-226 + Ra-228 MCL of 5

pCi/L.

Ra-226 MCL of 20 pCi/L; Ra-228 MCL

of 20 pCi/L.

Maintain current MCL based on corrected estimates of risk of current

MCL.

Beta/Photon

Emitters MCL.

4 mrem: Methodology for deriving individual concentration limits incorporated by reference; MCL = sum of

the fractions of dose from one or

more contaminants; risks estimated

not to exceed 5.6×10¥5.

4 mrem ede (Effective Dose Equivalent). Derived concentration limits

changed to reflect new dose limit;

Current estimate of associated risks

for these concentration limits are between 10¥4 and 10¥3 for most.

Maintain current MCL based on corrected estimates of risk of current

MCL.

Gross alpha MCL 15 pCi/L excluding U and Rn, but including Ra-226.‘‘Adjusted’’ gross alpha MCL of 15 pCi/

L, excluding Ra-226, radon, and uranium.

Maintain current MCL based on unacceptable risk level of 1991 proposed

MCL.

Polonium-210 ....... Included in gross alpha ......................... Included in gross alpha ......................... No changes to current rule. Monitoring

required under the UCMR rule. Future action may be proposed at a

later date.

Lead-210 .............. Not Regulated ....................................... Included in beta particle and photon radioactivity; concentration limit proposed at 1 pCi/L.No changes to current rule. Monitoring

required under the UCMR rule. Future action may be proposed at a

later date

Uranium MCL ....... Not Regulated ....................................... 20 μg/L or 30 pCi/L w/ option for 5–80

μg/L.

Three options being considered: 20,

40, 80 μg/L and pCi/L

Ra-224 .................. Part of gross alpha, but sample holding

time too long to capture Ra-224.

Part of gross alpha, but sample holding

time too long to capture Ra-224.

Same as current rule, but Ra-224 may

be addressed in a future proposal.

Radium monitoring Ra-226 linked to Ra-228; measure Ra228 if Ra-226>3 pCi/L and sum.Measure Ra-226 and -228 separately. Measure Ra-226 and -228 separately

Monitoring baseline.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.

Annual samples for 3 years; Std Monitoring Framework: >50% of MCL required 1 sample every 3 years;

<50% of MCL enabled system to

apply for waiver to 1 sample every 9

years.

Implement Std Monitoring Framework

as proposed in 1991. Four initial consecutive 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 radioactivity has a unique schedule—see

Section III, part K).

Beta monitoring .... Surface water systems >100,000 population Screen at 50 pCi/L/; vulnerable

systems screen at 15 pCi/L.

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.

Same as 1991 proposal with clarifications.

Gross alpha monitoring.Analyze up to one year later ................. Six month holding time for gross alpha

samples; Annual compositing of

samples allowed.

As proposed in 1991. Recommendation

to analyze within 48–72 hours to

capture Ra-224.

Analytical Methods Provide methods ................................... Method updates proposed in 1991;

Current methods were updated in

1997.

Current methods with clarifications.

II. 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 (radium226 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.

In 1983 and 1986, EPA published an

Advanced Notice of Proposed

Rulemaking (ANPRM) requesting

additional information and comments

on radionuclides and numerous organic

and inorganic contaminants in drinking

water. The 1986 SDWA Amendments

identified 83 contaminants for EPA to

regulate, including the currently

regulated radionuclides, which lacked

an MCLG, and two additional

radionuclides, uranium and radon. The

Amendments also declared the 1976

interim standards to be final National

Primary Drinking Water Regulations.

In 1996, Congress again amended the

SDWA. These amendments included

new and revised provisions that must be

considered when revising drinking

water regulations. Among these are the

Federal Register / Vol. 65, No. 78 / Friday, April 21, 2000 / Proposed Rules 21579

health protection clause (section

1412(b)(9)) which requires that ‘‘any

revision of a national primary drinking

water regulation (NPDWR) shall be

promulgated in accordance with this

section, except that each revision shall

maintain, or provide for greater

protection of the health of persons.’’

The 1996 Amendments also provide

for a cost-benefit analysis when

publishing a proposal for new NPDWRs

pursuant to section 1412 (b)(6). While

the EPA had proposed the radionuclides

rule prior to these Amendments, the

Agency nevertheless conducted an

analysis of the costs and associated

benefits of all of the options described

in today’s Document. These analyses

serve to update and revise the costs and

benefits estimated for the 1991 proposed

rule. For the uranium standard, the

Agency solicits comment on the

possible use of its new discretionary

authority at section 1412(b)(6) of the

SDWA, which allow for a proposed

regulatory level to be set higher than the

feasible level, after the Agency has made

a determination that the benefits do not

justify the costs at the feasible level.

Note that section 1412(b)(6) applies to

new standards (uranium), not to the

revision of existing standards (combined

radium-226 and -228, gross alpha, and

beta particle and photon radioactivity).

Where we expect to maintain current

standards at their existing levels, no

additional analysis was undertaken

because the rule is already in effect.

B. The 1991 Proposal

In 1991, EPA proposed new

regulations for uranium and radon, as

well as revisions to the existing

regulations. The proposal included the

following features: (1) an MCLG of zero

for all ionizing radiation; (2) revised

MCLs for beta particle and photon

radioactivity, radium-226, radium-228,

and gross alpha emitters; (3) proposed

MCLs for uranium and radon; and (4)

revisions to the categories of systems

required to monitor, the monitoring

frequencies, and the appropriate

screening levels. EPA received

comments on the new data and

regulatory options presented in the 1991

proposal. However, the proposal was

never promulgated as a final rule 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.

III. Overview of Today’s Document

Additional data since the 1991

proposal suggest a need to retain some

portions of the proposal, while retaining

much of the current rule. Any changes

that are finalized must meet the

provisions for public health protection

in accordance with the 1996

Amendments. EPA has presented its

approach for finalizing the non-radon

portions of the 1991 radionuclides

proposal at several public meetings.

In December 1997 EPA held a public

forum (stakeholder meeting) to discuss

the requirements and limitations of the

new Amendments pertaining to

revisions to the radionuclide regulation.

The Agency discussed most of the

concepts presented in this document

and received valuable feedback from the

public, the regulated community, and

other Federal Agencies. In this

Document, EPA is presenting the

current information and options upon

which the Agency will make its

decisions regarding revisions to the

existing standards. At the same time, the

Agency is requesting additional data

and comments on the approach EPA

expects to take in formulating the final

rule.

The most significant new information

concerns the occurrence, monitoring,

and health effects of radionuclides in

drinking water. Recent data suggest a

more widespread occurrence of certain

radionuclides which may point to a

need for improved monitoring for these

radionuclides in certain areas of the

country. Conversely, a better

understanding of the occurrence

patterns may also indicate the need for

less frequent monitoring. The newest

health effects models, which are based

on improved age-dependent biokinetic

and dosimetric models of the effects of

ionizing radiation on the body and more

recent epidemiological information,

reveal that radionuclides generally

present a somewhat greater risk than the

estimates of previous models, including

the 1991 RADRISK model. EPA’s

publication ‘‘Federal Guidance Report

13’’ (FGR–13, EPA 1999b) discusses the

newest risk modeling. The resulting risk

estimates based on of the new health

effects models are largely the reason for

the publication of this document. The

21580 Federal Register / Vol. 65, No. 78 / Friday, April 21, 2000 / Proposed Rules

1 If one ranked, from lowest to highest, the

average daily water consumption levels for every

CWS 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.

following are some aspects of the NODA

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 whichever risk provides the

greater protection for MCL changes, a

1×10¥4 risk of cancer incidence, or a

mortality risk at half the incidence,

5×10¥5. The risk of death at 5×10¥5 is

the more protective if the mortality rate

from a particular radionuclide is more

than 50%, which is true for most of the

radionuclides. However, for the thyroid,

the mortality rate from thyroid cancer is

at 10%. Protecting at 1×10¥4 incidence

corresponds to a mortality at 1x10¥5.

Conversely, protecting at 5×10¥5

mortality with only a 10% mortality rate

allows an incidence, of 5×10¥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

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 1×10¥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 1×10¥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 7.7×10¥5. The most current risk

estimate for Ra-228 at 20 pCi/L

7.7×10¥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 1.7×10¥4 in 1991. However, based

on the newest science, these individuals

would be exposed to lifetime excess

risks of 1×10¥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-sexspecific risk coefficients with age-sexspecific intake data and age-sex-specific

survival data.

A separate risk analysis for children

was performed and is described in

appendix II (Health Effects), part C.

Risks to children are explicitly

considered when setting MCLs for

radionuclides. In the case of the

regulated water systems (currently,

community water systems), children are

fully protected. In the case of the

unregulated systems of potential

concern (non-transient non-community

water systems, NTNCWSs), the analysis

is more complicated. Risks to children

served by NTNCWSs are discussed in

appendix II, part C, number 3.

Federal Register / Vol. 65, No. 78 / Friday, April 21, 2000 / Proposed Rules 21581

E. MCL for Beta Particle and Photon

Radioactivity

1. EPA’s Plans for Finalizing the 1991

Proposed MCL for Beta and Photon

Radioactivity

This section presents the important

considerations that have led EPA to

consider retaining the current MCL for

beta particle and photon radioactivity

when the 1991 proposal is finalized in

November of 2000. EPA is, however,

also considering finalizing the 1991

proposed changes to the monitoring

requirements for beta particle and

photon radioactivity, as described later

in this section. The current MCL is (40

CFR 141.16):

(a) The average annual concentration

of beta particle and photon radioactivity

from man-made radionuclides in

drinking water shall not produce an

annual dose equivalent to the total body

or any internal organ greater than 4

millirem/year.

(b) Except for the radionuclides listed

in Table A, the concentration of manmade 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 CONCENTRATIONS ASSUMED TO

PRODUCE A TOTAL BODY OR ORGAN

DOSE OF 4 MREM/YEAR.

Radionuclide Critical organ pCi per

liter

Tritium ............. Total body ....... 20,000

Strontium-90 .... Bone marrow .. 8

Following these instructions leads to

a unique list of concentration limits for

168 other man-made radionuclides. This

list is included in today’s document in

appendix II, ‘‘Health Effects.’’

The 1991 proposed MCL for beta

emitter and photon radioactivity was 4

mrem-ede (effective dose equivalents),

with the footnote:

‘‘NOTE. —The unit mrem-ede/yr refers to

the dose committed over a period of 50 years

to reference man (ICRP 1975) from an annual

intake at the rate of 2 liters of drinking water

per day.’’

Following these instructions leads to

a unique list of concentration limits for

230 radionuclides. EPA has determined

that there is no way to update the 4

mrem dose basis (1976) for the beta

particle and photon radioactivity MCL

without the extensive process of a new

proposal. While some stakeholders have

suggested that reverting to the existing

rule for beta particle and photon

radioactivity (‘‘beta emitters’’) is relying

on ‘‘old science,’’ it should be pointed

out the newest risk estimates, based on

the peer-reviewed Federal Guidance

Report 13, indicates that the risks

associated with the 1991 proposed MCL

of 4 mrem-ede (effective dose

equivalents) are above the 10¥4 risk

level (10¥3 to 10¥4) for many of the beta

emitters. Figure 1 shows the most

current risk estimates for the beta

emitter concentration limits derived

under both the current and proposed

MCLs. As the figure shows, the current

MCL results in concentration limits

with risks that fall within the Agency’s

risk range goal of 10¥6 to 10¥4 (while

some are slightly above and some

slightly below, all round to values

within these orders of magnitude).

BILLING CODE 6560–50–U

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

BILLING CODE 6560–50–C

Federal Register / Vol. 65, No. 78 / Friday, April 21, 2000 / Proposed Rules 21583

In summary, the Agency fully

recognizes that the dose-based MCL of

4 mrem/year is based on older scientific

models. However, the Agency has

decided to retain the current MCL given

that:

• Federal Guidance Report 13 (FGR–

13, EPA 1999b) demonstrates that the

1991 proposed MCL of 4 mrem-ede/year

results in concentration limits that are

outside the 10¥6 to 10¥4 range;

• FGR–13 demonstrates that the

current MCL of 4 mrem/year results in

concentration limits that are within the

10¥6 to 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 Pb210 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 radium226 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 Ra226 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 5×10¥5 and 2 ×10 ¥4,

averaging 1×10¥4. In 1991 the RADRISK

model calculated that a 1×10¥4 risk

corresponded to Ra-228 at 26 pCi/L and

Ra-226 at 22 pCi/L.

Table III–1 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 III–1.—CHANGES IN ESTIMATED RISKS FOR VARIOUS RA-226 AND RA-228 LEVELS

Year model used

Radium-228 Radium-226

Concentration pCi/LPrevious risk

estimate

Current risk

estimate

Concentration pCi/LPrevious risk

estimate

Current risk

estimate

2000 FGR–13 .................................................... 5 2 × 10¥4 2 × 10¥4 5 7.3 × 10¥5 7.3 × 10¥5

2000 FGR–13 .................................................... 2.5 1 × 10¥4 1 × 10¥4 6.85 1 × 10¥4 1 × 10¥4

1994 FGR–11 .................................................... 11 1 × 10¥4 4.5 × 10¥4 10 1 × 10¥4 1.5 × 10¥4

1991 RADRISK .................................................. 26 1 × 10¥4 1 × 10¥3 22 1 × 10¥4 3.3 × 10¥4

1991 RADRISK proposed MCL ......................... 20 7.7 × 10¥5 7.7 × 10¥4 20 9.1 × 10¥5 2.9 × 10¥4

1991 RADRISK .................................................. 5 1.9 × 10¥5 2 × 10¥4 5 2.3 × 10¥5 7.3 × 10¥5

21584 Federal Register / Vol. 65, No. 78 / Friday, April 21, 2000 / Proposed Rules

TABLE III–1.—CHANGES IN ESTIMATED RISKS FOR VARIOUS RA-226 AND RA-228 LEVELS—Continued

Year model used

Radium-228 Radium-226

Concentration pCi/LPrevious risk

estimate

Current risk

estimate

Concentration pCi/LPrevious risk

estimate

Current risk

estimate

1976* .................................................................. 5 1 × 10¥4 2 × 10¥5 5 1 × 10¥4 7.3 × 10¥5

*The risk of either radium-226 or radium-228 at 5 pCi/L was believed to be between 5×10¥5 and 2×10¥4 in 1976. The average would have

been 1×10¥4.

The 1991 estimated risk

corresponding to 20 pCi/l of Ra-226 in

addition to 20 pCi/l of Ra-228 was

thought to be 1.7 × 10¥4. However, the

current risk estimate based on FGR–13

(EPA 1999b) for 20 pCi/l of Ra-226 in

addition to 20 pCi/l of Ra-228 is 1×10¥3

(one in a thousand), an order of

magnitude (ten times) above the

acceptable risk of 1×10¥4.

In contrast, maintaining the current

standard would allow a maximum

lifetime risk of 2×10¥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 were all radium-228, a

relatively rare occurrence situation. If

the radium present were all radium-226,

the risk would be 7×10¥5, 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¥5; and

• the 1991 proposed MCLs for Ra-226

and Ra-228 have risks as high as

1×10¥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 Ra226 would be in compliance with the

combined radium MCL, but would have

an associated lifetime excess cancer

morbidity risk of 2 × 10¥4, which

exceeds the risk ceiling on 1 × 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 tradeoff 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 radium228 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 Ra228 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 radionuclide 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 radium228 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 Ra226 is part of the uranium series

(relatively mobile parent) and Ra-228 is

part of the thorium series (immobile

parent), Ra-226 can and does mobilize

in waters containing Ra-228 more

frequently than the reverse situation.

These observations indicate that Ra-226

and Ra-228 may be expected to

significantly co-occur, but that the

correlation will not be strong enough to

use the occurrence of one to predict the

other with acceptable certainty. Recent

Federal Register / Vol. 65, No. 78 / Friday, April 21, 2000 / Proposed Rules 21585

studies support this conclusion (EPA

2000a).

This conclusion indicates that the

current monitoring screen for Ra-228

based on Ra-226 is not reliable.

Therefore as proposed in 1991, EPA is

considering requiring separate

monitoring and analysis of both radium226 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 manmade 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

radiotoxic element in the uranium

decay chain. In 1976, the risk resulting

from exposure to 10 pCi/L of polonium210 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 the10 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 5×10¥5 to 2×10¥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 pCi/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/l 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 and 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 followon survey by EPA and the USGS has

demonstrated that radium-224 may be

present in significant quantities in

ground water, especially where its

decay chain ancestor radium-228 is

present. Although it is included in the

(gross) alpha MCL, it was not targeted

specifically for several reasons: (1) It

was not believed to be a health risk, (2)

21586 Federal Register / Vol. 65, No. 78 / Friday, April 21, 2000 / Proposed Rules

it was not known to be prevalent and (3)

sampling it at a representative point

within the distribution system rather

than the entry point to the system

allowed decay. However, newer FGR–13

risk estimates (EPA 1999b), coupled

with the greater occurrence, and the

1991 proposal to sample at the entry

point to the distribution system, now

make radium-224 a concern.

Radium-224 is a naturally occurring

radioisotope, which is part of the

thorium decay chain. It emits alpha

particles and has a half-life of 3.66 days.

The decay of its progeny via alpha and

beta decay also happens very quickly. In

approximately 4.1 days, an original

radium-224 atom has decayed to stable

lead-208 by emission of an equivalent of

4 alpha and 2 beta particles. A gross

alpha analysis will detect 3 alpha

particle emissions including daughters

in equilibrium with the parent Ra-224.

If a sample analysis is done within 72

hours, preferably 48 hours, an

appropriate back-calculation can be

performed of the gross alpha count of

the sample water. Otherwise the

laboratory will significantly

underestimate the radium-224 and other

alpha emitters that may have been

originally present in the sample.

Under the current rule, utilities are

allowed to collect quarterly samples,

composite and analyze at the end of the

year. In 1991, EPA proposed a holding

time of 6 months for gross alpha.

However, neither the annual composite

under the current rule or the proposed

holding time of 6 months can

appropriately capture the presence of

alpha-emitting radium-224, or its

progeny in a gross alpha analysis. The

Agency intends therefore, to issue a

separate proposal to change the holding

time for gross alpha analysis to account

for the presence of radium-224 in the

sample.

At this point in time, the Agency

strongly recommends to States and

utilities that an alpha analysis be

performed within 48 to 72 hour after

sample collection to capture the

contribution of the alpha particles

arising from radium-224. In this NODA,

the Agency is reiterating and

underscoring its recommendation to

that effect as outlined in a memorandum

of January 27, 1999 from Cynthia

Dougherty, Director of the Office of

Ground Water and Drinking Water (EPA

1999a). For systems to whom a rapid

analysis might be a burden, a reasonable

screening tool for the presence of Ra-224

under many geochemical circumstances

is the presence of its radiological

ancestor, Ra-228. Since systems will

monitor for Ra-228, the result can serve

as a general proxy for the presence or

Ra-224 for the purposes of

prioritization. It is not definitive and

would not be an acceptable substitute

for a rapid analysis of gross alpha or Ra224. 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 ×

10¥5 or one in 20,000. Because radium224 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 dose).

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 ×

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 (μg)

while the radiation activity is measured

in picoCuries. In 1991, EPA proposed a

limit on uranium of 20 μg per liter (μg/

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 μg/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 μg/L, based upon protection

from kidney toxicity. The derivation of

this number is based on newer, more

complete studies which have also

resulted in a lower uncertainty factor,

now 100-fold. In addition, the

contribution to ingestion from drinking

water relative to food or inhalation, the

relative source contribution (RSC), has

been recalculated. Drinking water is

now considered to contribute 80 percent

of a person’s total daily uranium intake.

This has the effect of permitting 80% of

the reference dose (RfD) to be occupied

by the drinking water component of

diet. Both a lower uncertainty factor

coupled with a lower food intake and

higher proportional contribution from

drinking water to total intake, might

suggest the allowance of a higher

regulatory limit; however, the more

recent studies have offset this by

revealing a lower observed effect level

for kidney toxicity. The recalculated

‘‘safe level’’ for kidney toxicity remains

20 ug/L. The derivation of the

uncertainty factor is based on the types

of uranium health data available. EPA’s

policy for uncertainty factors for

estimating LOAELs is summarized in 63

FR 43756 (August 14, 1998, ‘‘Draft

Water Quality Criteria Methodology

Revisions: Human Health’’). The

derivation is described in appendix II.

Federal Register / Vol. 65, No. 78 / Friday, April 21, 2000 / Proposed Rules 21587

Uranium is also classified as a

carcinogen because of its radioactivity,

and resulting emissions of ionizing

radiation. The two most prevalent

isotopes of uranium, uranium-234 and

uranium-238, have very different halflives 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 μg.

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 μg/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 ‘‘nonquantifiable 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 μg/L are low (0.2

to 2 cases for 20 μg/L and 0.04 to 1.5

cases for 40 μg/L). In terms of exposure

avoided for kidney toxicity, around 500

thousand to two million persons are

exposed above 20 μg/L and 50 thousand

to 900 thousand persons are exposed

above 40 μg/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 μg/L (5 pCi/L was evaluated),

EPA determined that levels below 20

pCi/l 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 μg/L) was based

on uranium kidney toxicity, as

previously described. The

corresponding risk of cancer at a

concentration of 20 μg/l is now

estimated to be approximately 5 × 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 μg/L and 80 μg/L.

EPA estimates that a level of 40 μg/L

would correspond to a cancer risk of

approximately a 1 × 10¥4, thus

providing cancer risk protection within

the Agency’s traditional risk range. A

level of 40 μg/L would represent a

slightly higher risk of kidney toxicity.

At a level of 80 μg/L, the cancer

mortality risk is approximately 2 ×

10¥4, which is above the Agency’s

acceptable risk range. At 80 μg/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 μg/

L than at an MCL of 40 μg/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 μg/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 μg/L, 40

μg/L, and 80 μg/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 μg/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 μg/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 5×10¥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 × 10–4, which may be

more acceptable, considering the costs.

Likewise, a doubling of risk to 2 × 10–4

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 μg/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/μg 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 μg/L from

mass to activity using a ratio of 0.9 for

levels above 3.5 μg/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 μg/L would be 17.3 pCi/L rounded to

17 pCi/L. Coupled with the knowledge

that the concentration of uranium

isotopes varies from place to place, the

Agency is led to consider an MCL that

21588 Federal Register / Vol. 65, No. 78 / Friday, April 21, 2000 / Proposed Rules

2Throughout this discussion, exposures and risks

were 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 noncontrollable factor since private wells are not

regulated by the Safe Drinking Water Act.

is protective in any location against both

toxicity (μg/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 μg/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 μg/L could be

exceeded. If the gross alpha test is

between 3 and 5.5 pCi/L, the mass of 20

μg/L could be exceeded if all the activity

were coming from uranium-238.

Therefore a fluroimetric test for uranium

mass concentration (μg/L) or an alpha

spectrometry test for the activities (pCi/

L, converted to μg/L using standard

isotopic conversion factors) of the

various isotopes present would be

necessary to determine the uranium

concentration in μg/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 μg/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 × 10¥5 or five in one hundred

thousand);

• Regulate at 40 μg/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 × 10¥4 or one in ten thousand,

which is the Agency’s usual upper

cancer risk target);

• Regulate at 80 μg/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 × 10¥4

or two in ten thousand, which is above

the Agency’s usual upper cancer risk

target).

In summary, EPA believes that 20 μg/

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 × 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 μg/L, but

solicits comment on this and the

previously-described regulatory options,

together with any supporting rationale

or data commenters wish to provide.

I. Inclusion of Non-Transient NonCommunity Water Systems

Today’s document is soliciting

comment on several approaches for

covering Non-Transient NonCommunity (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)(1)(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 source 3. 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

Federal Register / Vol. 65, No. 78 / Friday, April 21, 2000 / Proposed Rules 21589

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 are assumed to perfectly

attend and work at the same facility for forty-five

years. All of these assumptions are under

continuing investigation and will likely be revised

downward in the future as the Agency is able to

gather further information.

5As 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.

6For 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 are

reasonable, based on levels observed in small

ground water community water systems.

than five percent of lifetime

consumption 4.

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

exposure 5, multiple water system

exposure scenarios were considered in

the modeling effort 6. Tables III–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 Alpha Radium 226 Radium 228 Uranium

School Students ................................................................. 2×10¥5 0.9–1.1 ×10¥5 2–3×10¥5 0.7–0.9×10¥5

Day Care Children ............................................................. 2–3×10¥5 0.6–0.7×10¥5 2–3×10¥5 0.8–1x10¥5

Factory Worker .................................................................. 1–2×10¥5 1×10¥5 2–3×10¥5 1×10¥5

All NTNC Water Systems .................................................. 0.3–0.4×10¥5 0.2–0.3×10¥5 0.5–0.7×10¥5 0.2×10¥5

Note that Radium 224 is being used as a surrogate for alpha emitters.

TABLE III–3.—SELECTED SECTOR AND OVERALL NTNC, INDIVIDUAL RISK PATTERNS

[Lifetime cancer risk for individuals using 90th percentile consumption levels]

Sector Alpha Radium 226 Radium 228 Uranium

School Students ................................................................. 0.5–0.6×10¥4 0.3×10¥4 0.6–0.7×10¥4 0.3×10¥4

Day Care Children ............................................................. 0.7–0.8×10¥4 0.2×10¥4 0.6×10¥4 0.3–0.4×10¥4

Factory Worker .................................................................. 0.5–0.6×10¥4 0.3–0.4×10¥4 0.7–0.8×10¥4 0.5–0.6×10¥4

All NTNC Water Systems .................................................. 0.2×10¥4 0.1×10¥4 0.2–0.3×10¥4 0.1–0.2×10¥4

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

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.

21590 Federal Register / Vol. 65, No. 78 / Friday, April 21, 2000 / Proposed Rules

The States (or primacy agency) would

determine which NTNC systems are

likely to be using contaminated water

systems, based on CWS monitoring

results. These systems may then be

required to monitor and meet CWS

MCLs for gross alpha and combined

radium and other relevant

radionuclides. EPA is considering:

• Requiring targeted NTNC systems to

monitor and meet the CWS MCLs for all

or selected radionuclides, where

targeting is determined by the State

based on whether the NTNC system is

using source water for which CWSs

have reported MCL violations for

radionuclide in question;

• Requiring targeted NTNC systems to

monitor and post notice if the system

exceeds the CWS MCL, using the same

definition of targeting as in the first

option;

• Issuing guidance that recommends

that targeted NTNC systems monitor

and meet the CWS MCLs, using the

same definition of targeting as in the

first option.

The Agency requests comments on

these options and any supporting

rationale for such a decision. The

Agency is also interested in receiving

comments on other options such as

extending full coverage of the rule to

NTNCs and not extending any aspect of

the radionuclides NPDWRs to NTNC

systems. The Agency will decide, as

part of the upcoming finalization of the

1991 proposal, to incorporate what it

considers to be the most appropriate

option in view of available the data and

information.

J. 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 III 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 fiftysix were actually approved in the March

5, 1997 final methods rule (62 FR 10168;

EPA 1997a). In addition to these fiftyfour, 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 alphaemitting particles and gross betaemitting 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 halflife 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 rule (56 FR

33050; EPA 1991), EPA cited cost

estimates for radiochemical analyses.

The Agency updated these costs

estimates by surveying a small number

of radiochemical laboratories (no more

than 9 laboratories) (EPA 2000a). The

revised cost estimates are shown in

Table III–3 (appendix III). Because this

information is based on a limited

number of laboratories, the slight

increase in costs from 1991 to 1999 may

be due to either statistical uncertainty or

possibly others factors such as inflation.

After the 1991 proposed rule, there

were several comments regarding

analytical costs. One commenter stated

the costs of analysis for radium-226,

radium-228, radioactive strontium and

total strontium were unrealistically low.

The Agency can neither agree nor

disagree. As noted earlier, EPA revised

the cost estimates for radiochemical

analysis. Both the 1991 costs estimates

and the revised cost estimates were from

small surveys and may not be truly

representative of the actual costs for

some radiochemical analyses.

Comparison of the estimated costs from

1991 with the revised cost estimates

indicate the costs for some analyses to

similar, while for other analyses, cost do

appear to be higher. The Agency solicits

comments and factual data that would

clarify this matter.

Several commenters stated that small

systems, which are likely to need only

a few analyses, cannot take advantage of

rates for volume sample analyses. The

Agency agrees that individual small

systems may not be able to take

advantage of lower bulk analysis costs.

To alleviate cost burdens, small systems

may want to consider pooling their

analytical needs with other small

systems to negotiate for bulk rates.

Federal Register / Vol. 65, No. 78 / Friday, April 21, 2000 / Proposed Rules 21591

5. Externalization of the Performance

Evaluation Program

Due to resource limitations, on July

18, 1996 (61 FR 37464; EPA 1996b),

EPA proposed options for the

externalization of the PE studies

program (now referred to as the

Proficiency Testing or PT program).

After evaluating public comment, in the

June 12, 1997 final notice EPA (62 FR

32112; EPA 1997b):

decided on a program where EPA would

issue standards for the operation of the

program, the National Institute of Standards

and Technology (NIST) would develop

standards for private sector PE (PT) suppliers

and would evaluate and accredit PE

suppliers, and the private sector would

develop and manufacture PE (PT) materials

and conduct PE (PT) studies. In addition, as

part of the program, the PE (PT) providers

would report the results of the studies to the

study participants and to those organizations

that have responsibility for administering

programs supported by the studies.

EPA has addressed this topic in

public stakeholders meetings and in

some recent publications. For more

information, readers are referred to the

aforementioned Federal Register

notices. More information about

laboratory certification and PT (PE)

externalization can be accessed at the

OGWDW laboratory certification

website under the drinking water

standards heading (www.epa.gov/

safewater). At this time, it is difficult to

ascertain how and if externalization of

the PT program will affect

radiochemical laboratory capacity and

the cost of radiochemical analyses. In

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 σ, where σ is the standard

deviation of the net counting rate of the

sample).’’ Table III–4 in the appendix

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. In the 1991

proposal (56 FR 33050; EPA 1991), EPA

proposed using the method detection

limit (MDL) and the practical

quantitation level (PQL) as measures of

performance for specific radioanalytical

methods. Acceptance limits based on

the PQLs, which were derived from

performance evaluation studies, were

also proposed in the 1991 rule. Some

commenters found the use of acceptance

limits confusing and the relationship to

the actual method performance was not

clear. With perhaps the exception of

uranium, the Agency will not go

forward with the proposed acceptance

limits, PQL, or MDL. Because uranium

has never been regulated, it did not have

a detection limit in the CFR and one has

never been proposed. In 1991, EPA did

propose a PQL of 5 pCi/L with an

acceptance limit of +/¥ 30%. Although

it is believed that a detection limit for

uranium would be very similar to the

PQL, because a detection limit has never

been proposed, the Agency may have to

adopt the PQL for uranium until a

detection limit is proposed. For the

other radionuclides, which are

regulated, the Agency believes the

current 1976 detection limit

requirements are most appropriate. The

existing definition of the detection limit

takes into account the influence of

various factors (efficiency, volume,

recovery yield, background, counting

time) that typically vary from sample to

sample. Furthermore, the detection limit

is computed for each individual sample

and does not represent an idealized set

of measurement parameters. Therefore,

the detection limit reflects the expected

random uncertainty for a given sample

analysis.

7. Performance Based Measurement

System

On October 6, 1997, EPA published a

Notice of the Agency’s intent to

implement a Performance Based

Measurement System (PBMS) in all of

its programs to the extent feasible (62

FR 52098; EPA 1997c). EPA is currently

determining how to adopt PBMS into its

drinking water program, but has not yet

made final decisions. When PBMS is

adopted into the drinking water

program, its intended purpose will be to

increase flexibility in laboratories in

selecting suitable analytical methods for

compliance monitoring, significantly

reducing the need for prior EPA

approval of drinking water analytical

methods. Under PBMS, EPA will

modify the regulations that require

exclusive use of Agency-approved

methods for compliance monitoring of

regulated contaminants in drinking

water regulatory programs. EPA will

probably specify ‘‘performance

standards’’ for methods, which the

Agency would derive from the existing

approved methods and supporting

documentation. A laboratory would be

free to use any method or method

variant for compliance monitoring that

performed acceptably according to these

criteria. EPA is currently evaluating

which relevant performance

characteristics under PBMS should be

specified to ensure adequate data

quality for drinking water compliance

purposes. After PBMS is implemented,

EPA may continue to approve and

publish compliance methods for

laboratories that choose not to use

PBMS. After EPA makes final

determinations about the

implementation of PBMS in programs

under the Safe Drinking Water Act, the

Agency would then provide specific

instruction on the specified

performance criteria and how these

criteria would be used by laboratories

for compliance monitoring of SDWA

analytes.

K. Monitoring

1. Features of Today’s NODAA

EPA’s 1976 regulations for

radionuclides in drinking water

contained separate monitoring

requirements for radiums, alpha

emitters, and man-made beta and

photon emitters. In 1991, EPA proposed

to make modifications to the 1976

regulations to expand the scope of

coverage to include non-transient noncommunity water systems, to change the

monitoring location and monitoring

frequencies, and to incorporate

monitoring requirements for radon and

uranium. A summary of the 1976

requirements and proposed changes in

1991 are presented in this section.

In today’s document EPA is

suggesting merging the current

requirements and the 1991 proposed

requirements into a unified system

which is consistent with the

Standardized Monitoring Framework

(SMF), the current rule, and the

proposed changes which are still

germane. EPA is soliciting comment on

monitoring at the entry points to the

distribution system, as proposed in

1991, to ensure equal protection for all

customers, under the sampling schedule

of the SMF. EPA believes that this will

increase consistency between

monitoring requirements for

radionuclides and the other regulated

contaminants. As described in section

III, part I (‘‘Inclusion of Non-Transient

Non-Community Water Systems’’), EPA

is considering several options for NTNC

water systems, some of which would

require monitoring. Because some

monitoring provisions of the 1991

proposal were based on the proposed

MCLs and not the current MCLs, their

application to the current levels may

entail a slightly different construct than

in 1991. To the extent comments reveal

aspects of the framework which need to

be addressed separately from the 1976

rule or 1991 proposal, EPA will return

21592 Federal Register / Vol. 65, No. 78 / Friday, April 21, 2000 / Proposed Rules

to the current rule’s framework and

propose to correct deficiencies via a

proposal which will address analytical

method issues as well, such as methods

for Ra-224, Po-210 and Pb-210.

2. Standardized Monitoring Framework

Per the current rule, once the

contaminant concentration in the water

is established by the average results for

four consecutive quarterly samples or by

suitable grandfathered data, a system

would be categorized as to whether it

was above or below 50% of the MCL for

that contaminant. In accordance with

the SMF, as proposed in 1991, EPA is

suggesting a tiered frequency for alpha

emitters, combined radium, and

uranium. This would entail one sample

every three years for compliant systems

with annual average contaminant levels

above 50% of the MCL. For compliant

systems with annual average levels

below 50% of the MCL for these

contaminants, one sample would be

required every 6 years; non-detects, one

sample every 9 years. EPA believes this

system would align with the

standardized monitoring framework,

and would provide regulatory relief for

systems with 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 underrepresent 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, radium226/228, 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 wellfield, 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, Ra228. In the 1991 proposal, gross beta

compositing was prohibited.

Compositing for other nuclides was

Federal Register / Vol. 65, No. 78 / Friday, April 21, 2000 / Proposed Rules 21593

allowed for up to five sampling points

within one system; if the result for the

composite was more than 3 pCi/l 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/l. 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 radium226 and radium-228 at 20 pCi/L each,

since 1⁄5 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 (1⁄10) 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 Ra228, 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 nondetect (9), as previously discussed.

Decreased and increased monitoring

would be based on the result of the

analysis of the most recent required

sample(s).

Entry point monitoring: Monitoring at

entry points to the distribution system

would be a requirement per the 1991

proposal unless EPA receives comments

with compelling reasons for not doing

so.

Sample Compositing: To decrease the

burden of monitoring at distribution

entry points, EPA is contemplating

allowance of sample compositing for

radium-226 or radium-228, but only

when results will be indicative of the

true level at a single entry point

(temporal compositing). According to

the proposal, systems would be required

to analyze for Ra-228 separately from

gross alpha or Ra-226. The Agency sees

no reason why four separate samples

from a single entry point (collected 60

days apart) could not be either analyzed

and averaged or composited in the

laboratory and analyzed, to determine

future monitoring frequency. Therefore,

EPA is suggesting for public comment

that systems take the average analytical

results from four individual samples, or

the composite of four samples from each

entry point, in order to determine future

frequency.

As discussed previously, EPA does

not contemplate allowing compositing

of multiple entry points for derivation of

combined radium results. EPA requests

comment on any element of the

foregoing discussion.

9. Alpha Emitters

Standardized monitoring: Same as for

combined radium (see previous

discussion).

21594 Federal Register / Vol. 65, No. 78 / Friday, April 21, 2000 / Proposed Rules

Decreased and increased monitoring:

Same as for combined radium (see

previous discussion).

Entry point monitoring: Same as for

combined radium (see previous

discussion).

Sample Compositing: The current rule

allows compositing of four samples in a

laboratory or the averaging of four

separate analyses. Under the 1991

proposal and the current rule, systems

would be allowed to composite

annually for samples taken from single

entry points (temporal compositing)

and, under the 1991 proposal, to

composite samples representing up to

five entry points with a six month

holding time (spatial compositing).

10. Uranium

Standardized monitoring, monitoring

frequency, and entry point monitoring:

Same as for combined radium (see

previous discussion).

Sample Compositing: For systems

with gross alpha levels that are high

enough to warrant uranium monitoring,

annual composites for a single entry

point would be allowed. Compositing of

five samples representing five entry

points would be permitted. If the result

was greater than one fifth of the MCL,

the individual samples would have to

be analyzed or re-sampling and analysis

of the new individual samples would

have to occur.

11. Beta and Photon Emitters

Standardized monitoring framework,

decreased monitoring: Monitoring for

beta and photon emitters would follow

the same schedule as in the current rule.

Decreased monitoring is not envisioned

for beta and photon emitters since only

vulnerable systems would monitor,

although EPA 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/l 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 revisited 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 NonCommunity (NTNC) Systems

If EPA finalizes an option that

requires monitoring for some or all

NTNC systems, EPA wishes to make the

monitoring requirements consistent

between CWSs and those NTNC systems

required to monitor. See the previous

discussion for CWS monitoring for

details. As with CWSs, monitoring

under the SMF would be required at

entry points to the distribution system,

based on a nine-year cycle, consisting of

three, 3-year monitoring periods, with

provisions for reduced monitoring as

appropriate. If the radionuclides

NPDWRs for CWSs are fully extended to

NTNCWSs, the monitoring frameworks

would be the same.

Table III–4 summarizes the

monitoring frequencies for CWSs and

NTNC systems, under the options that

require monitoring:

Federal Register / Vol. 65, No. 78 / Friday, April 21, 2000 / Proposed Rules 21595

TABLE III–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 Initial baseline: one sample per year for 3

years.

Initial baseline: 4 consecutive quarterly samples taken within 3 years from effective

date or grandfathered data in previous compliance period.

If average > MCL=treat, etc ............................... Same as 1976 .................................................. Same as 1976.

If one or more samples >MCL, do quarterly

sampling until average < MCL.

Same as 1976 .................................................. Same as 1976.

If >50% of MCL, 4 Quarters every 4 years ........ If >50% of MCL, one sample every 3 yrs or

waiver to every 9 yrs.

Same as 1991 with no waiver.

If < 50% of MCL, 1 sample every 4 years ......... If <50% of MCL, one sample every 3 yrs or

waiver to every 9 years.

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

If no detect, 1 sample every 4 years ................. If no detect, one sample every 3 yrs or waiver

to every 9 yrs.

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 I–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 proposed at 30.

Same as 1991: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. Polonium-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 healtheffects 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 III–5 and III–6 summarize the

current and proposed monitoring

requirements and those suggested by

today’s document.

21596 Federal Register / Vol. 65, No. 78 / Friday, April 21, 2000 / Proposed Rules

TABLE III–5.—INITIAL (ROUTINE) MONITORING REQUIREMENTS

1976 1991 proposal 2000 NODA

GROSS ALPHA

CWSs: Four consecutive quarters at representative point(s) within the distribution system

every four years.

CWSs and NTNCWSs: Annual monitoring at

each entry point for first three years.

CWSs and NTNCWSs 1: Four consecutive

quarters of monitoring at each entry point,

anytime during first 3 years.

RADIUM

CWSs: Four consecutive quarters at representative point(s) within the distribution system

every four years. Initial monitoring is for radium-226. If radium-226 exceeds 3 pCi/L,

analysis for radium-228 is required. A gross

alpha measurement can be substituted for radium 226 and/or uranium monitoring if the

gross alpha measurement is below the applicable MCL(s).

CWSs and NTNCWSs: Annual monitoring for

each radium isotope (radium-226 and radium-228) at each entry point, for three

years.

CWSs and NTNCWSs: Four consecutive

quarters of monitoring for each radium isotope (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 determine compliance with both mass and activity either by 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 representative point(s) within the distribution system. Determine major constituents if exceed

screen of 50pCi/L Systems using water contaminated with effluent from nuclear facilities:

Quarterly monitoring 1 for gross beta and iodine-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 monitoring. Using a screen of 50 pCi/L, quarterly

monitoring for gross beta is required, along

with annual tritium and strontium-90 monitoring.

Vulnerable systems only CWSs and

NTNCWSs: (as designated by the State):

Two gross beta 14 screening levels are

being considered. Using a screen of 50 or

30 pCi/L, quarterly monitoring for gross

beta is required, along with annual monitoring 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: 1This 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 applicable MCL(s). 3Quarterly monitoring for gross beta would be based on the analysis of monthly samples or the analysis of a composite of three monthly samples. 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 consecutive quarterly samples) is less than 1⁄2 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 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 monitoring results

(‘‘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 1⁄2 MCL; or one

sample every nine years if previous results

are reliably and consistently at or below the

MDL.

Federal Register / Vol. 65, No. 78 / Friday, April 21, 2000 / Proposed Rules 21597

TABLE III–6.—REDUCED MONITORING REQUIREMENTS—Continued

1976 1991 proposal 2000 NODA

RADIUM

CWSs: One sample every four years if annual

average from previous results (four consecutive quarterly samples) is less than 1⁄2 MCL.

CWSs and NTNCWSs using ground water:

One sample every three years, if previous

monitoring results (from three years of annual 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 1⁄2

MCL; or one sample every nine years if

previous results are reliably and consistently 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 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 average

below MCL; one sample every six years if

previous results average at or below 1⁄2

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. Systems 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 monitoring 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 shortterm 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 2000, 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

as possible.

Under the Safe Drinking Water Act,

final rules become effective three years

after promulgation (November of 2003,

assuming that the rule becomes final in

November of 2000). The following

discussion assumes a promulgation date

of November 2000. For reasons

described in the monitoring section of

the NODA (section III, part K) and the

Appendices (appendix V), initial

monitoring will be required to

completed by December 31, 2007. Under

the Standard Monitoring Framework,

systems have three years to complete

the initial monitoring cycle of four

consecutive quarterly samples.

However, for reasons described in the

monitoring section of the NODA

(section III, part K) , systems will have

an additional year to complete the

initial monitoring cycle, which will

correspond to an end date of December

21598 Federal Register / Vol. 65, No. 78 / Friday, April 21, 2000 / Proposed Rules

31, 2007. This includes initial

monitoring for uranium, the new

monitoring requirements for radium228, 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 1996 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 nontransient, 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.

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.

The Agency will pursue the issue of a

timely analysis of 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 ShortLived 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). ‘‘Radium226 and Radium-228 in a Shallow Ground

Water, Southern New Jersey’’. Fact Sheet FS–

062–98. June 1998.

Appendix I—Occurrence

In order to estimate the total national costs

and benefits of revising the MCLs it is

necessary to develop updated national

estimates of the occurrence and exposure to

these radionuclide contaminants in drinking

water. Occurrence data and associated

analyses provide indications of the number

of public water supply systems with

concentration of radionuclides above the

revised MCL as well as the population served

by these systems. Monitoring and treatment

costs can be estimated from the occurrence

data.

A. Background

EPA conducted a nationwide occurrence

study of naturally occurring radionuclides in

Federal Register / Vol. 65, No. 78 / Friday, April 21, 2000 / Proposed Rules 21599

public water supplies called the National

Inorganic and Radionuclides Survey (NIRS)

(see EPA 1991, proposed rule). The objective

of NIRS was to characterize the occurrence of

a variety of constituents, including radium226, radium-228, uranium (mass analysis),

gross alpha-particle activity, and gross betaparticle 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 I–1.

TABLE I–1.—COMPARISON OF NIRS TARGET SAMPLE WITH FEDERAL REPORTING DATA SYSTEM (FRDS) INVENTORY

Population category (population range) Number of

FRDS sites*

Percentage of

FRDS sites

Number of

NIRS sites

Percentage of

NIRS sites

Very small (25–500) ................................................................................ 34,040 71.4 716 71.6

Small (501–3,300) ................................................................................... 10,155 21.3 211 21.1

Medium (3,301–10,000) ........................................................................... 2,278 4.8 47 4.7

Large and very large (10,001–>100,000) ................................................ 1,227 2.6 26 2.5

Total .............................................................................................. 47,700 100.1 1,000 100.0

* 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 radium228. 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 I–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 I–2.—PERCENT OF SAMPLES EXCEEDING SPECIFIED CONCENTRATION

Radionuclide

Total number of samplesPercent of samples exceeding given concentration (pCi/L)

1 2 3 5 7 10

Ra-224 ......................................................................................... 104 30 26 20 15 9 5

Ra-226 ......................................................................................... 104 33 22 17 10 5 2

Po-210 .......................................................................................... 95 3 1 1 1 0 0

Pb-210 .......................................................................................... 96 10 3 1 1 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 radium224 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 radium224; therefore results are possibly biased to

areas that would more likely have isotopes in

the thorium-232 decay series. In addition, the

correlations of radium-226 with radium-224

and radium-228 are only 0.51 and 0.61

respectively; consequently, the wells that

were sampled may not be located in areas

expected to have polonium-210 or lead-210.

Within these constraints, the new data help

to fill the gap in occurrence information that

existed for these isotopes. Polonium-210 was

found in concentrations exceeding 1 pCi/L in

only two wells. At this time, these

21600 Federal Register / Vol. 65, No. 78 / Friday, April 21, 2000 / Proposed Rules

observations could not be associated with

unique geochemical controls (as has been

accomplished in a previous study in Florida;

Harada et al., 1989) and further investigations

would be necessary to infer anything more

about the national distribution and

occurrence of polonium-210.

Approximately 12 percent of the samples

exceeded a lead-210 concentration of 1 pCi/

L; however only one sample was greater than

3 pCi/L. The greatest frequency of detection

was in the Appalachian Physiographic

Province of the northeastern United States,

especially in of Connecticut and

Pennsylvania. The geochemical mechanism

that controls lead-210 dissolution is also not

well established and needs further study,

though lead is less soluble than radium. In

addition, lead-210, like polonium-210, is

derived from a different decay chain than

radium-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. USGS 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 NIRS 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 betaparticle and gross alpha-particle activities,

tritium, strontium-89, strontium-90, cesium134, 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 pCi/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 betaparticle 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 betaparticle 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 naturallyoccurring 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. Radium228 and radium-228 in shallow ground

water, southern New Jersey. U.S. Geological

Survey Fact Sheet FS–062–98.

Szabo, Z., V.T. dePaul, and B. Parsa, 1998.

Decrease in gross alpha-particle activity in

water samples with time after collection from

the Kirkwood Cohansy aquifer system in

southern New Jersey: Implications for

regulations. Drinking Water 63rd annual

meeting American Water Works Association

New Jersey Section. Atlantic City, NJ.

Szabo, Z., and O.S. Zapecza, 1991,

Geologic and geochemical factors controlling

uranium, radium-226, and radon-222 in

ground water, Newark Basin, New Jersey:

Gundersen, L.C.S. and Wanty, R.B., eds.,

Field studies of radon in rocks, soils, and

water, U.S. Geological Survey Bulleting 1971,

p. 243–266.

USEPA. National Primary Drinking Water

Regulations; Radionuclides; Proposed Rule.

Federal Register. Vol. 56, No. 138, p. 33050.

July 18, 1991.

USEPA. ‘‘Technical Support Document for

the Radionuclides Notice of Data

Availability’’. Draft. March, 2000. (EPA

2000a)

Welch, A.H., Szabo, Z., Parkhurst, D.L.,

Van Meter. P.C., and Mullin, A.H., 1995,

Gross-beta activity in ground water: natural

sources and artifacts of sampling and

laboratory analysis: Applied Geochemistry, v.

10, no. 5, p. 491–504.

Zapecza, O. S., and Z. Szabo, 1986. Natural

radioactivity in ground water—a review. U.S.

Geological Survey National Water Summary

1986, Ground-Water Quality: Hydrologic

Conditions and Events, U.S. Geological

Survey Water Supply Paper 2325. pp. 50–57.

Appendix II—Health Effects

The following information summarizes the

salient changes in risk assessment

information and risk characterization

methodology during the past two decades.

The Technical Support Document (EPA

2000a) also provides additional information.

A. Use of Linear Non-Threshold Assumption

In estimating the health effects from

radionuclides in drinking water, EPA

subscribes to the linear, non-threshold model

which assumes that any exposure to ionizing

radiation has a potential to produce

deleterious effects on human health, and that

the magnitude of the effects are directly

proportional to the exposure level. The

Agency further believes that the extent of

such harm can be estimated by extrapolating

effects on human health that have been

observed at higher doses and dose rates to

those likely to be encountered from

environmental sources of radiation. The risks

associated with radiation exposure are

extrapolated from a large base of human data.

EPA recognizes the inherent uncertainties

that exist in estimating health impact at the

low levels of exposure and exposure rates

expected to be present in the environment.

EPA also recognizes that, at these levels, the

actual health impact from ingested

radionuclides will be difficult, if not

impossible, to distinguish from natural

disease incidences, even using very large

epidemiological studies employing

sophisticated statistical analyses. However,

in the absence of other data, the Agency

continues to support the use of the linear,

non-threshold model in assessing risks

associated with all carcinogens.

B. Continuous Improvements in Models, Data

Base

As various scientific institutions have

continued to collect data on the observed

effects of radiation from the cohort of bomb

survivors, patients with medical exposure,

and workers with occupational exposure;

continuous improvements have been possible

in models to extrapolate effects and to

estimate the risks of small exposures to

radiation from the natural environment or

man-made sources. The data have led to

Federal Register / Vol. 65, No. 78 / Friday, April 21, 2000 / Proposed Rules 21601

changes in risk estimates as summarized

here.

1. Basis of 1976 Estimates of Risk

• Risk of bone cancer from radium dial

painters.

• Autopsy radioassay (see EPA 2000a).

Body burden from natural intake or radium,

about 1 pCi/day.

• Estimate annual dose rate in several

organs from natural radium in rad/year.

• BEIR I 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 × 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 × 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 polonium210, 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 × 10¥6 per year, or a

lifetime cancer risk of 5.6 × 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 I 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 × 10¥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 × 10¥6

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 × 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 an 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 radium228 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¥4. The Agency no longer believes the

MCLs proposed in 1991 for radium-226 and

radium-228 are within the Agency’s

acceptable risk range.

i. Human and Animal Health Effects Data

Considered. In 1991, EPA based its risk

estimates for radium using information from

two epidemiological study groups. The first

group consisted of radium dial painters who

had ingested considerable amounts of radium

paint (containing various proportions of

radium-226 and radium-228) by sharpening

the point of their paint brush with the lips.

The second group consisted of patients in

Europe injected with a short-lived isotope of

radium, radium-224, for treatment of spinal

arthritis and tuberculous infection of the

bone (see EPA 2000a). The results of these

studies are described briefly next.

At high levels of exposure to radium,

several non-cancer health effects were

observed in radium dial painters, such as

benign bone growths, osteoporosis, severe

growth retardation, tooth breakage, kidney

disease, liver disease, tissue necrosis,

cataracts, anemia, immunological

suppression and death (see EPA 2000a).

21602 Federal Register / Vol. 65, No. 78 / Friday, April 21, 2000 / Proposed Rules

Exposed radium dial painters also

exhibited significantly elevated rates of two

rare types of cancer, 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

(see EPA 2000a). This is because these latter

cancers 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 2000a). 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 BEIR IV (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 radium226 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 ................................ Calculation of body burdens based on environmental studies and ratio of intakes.Calculation of body burdens based on

toxicokinetic models derived from studies of

patients injected with radium.

Dosimetry ........................................................... Calculation of absorbed dose based on organ

and tissue burden.

Calculation of absorbed dose based on organ

or tissue burden and cross irradiation terms

from all other organs.

Risk Coefficients ................................................. Risk estimated using the geometric mean of

the absolute and relative risk coefficients

from the 1972 BEIR I report.

Risk estimated using the absolute risk coefficient from the 1980 BEIR III report.

b. Basis for the 1991 MCL for 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¥6 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¥6 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 × 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 ThO2 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 × 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, 1991f).

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 highLET radiation exposure risks. Using

RADRISK, EPA estimated that, at a lifetime

fatal cancer risk level of 1 × 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¥4.

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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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 ICRP 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 ×

10¥5 because 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

to 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 II–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 × 10¥4, about

twice as high as the risk level estimated in

1976.

d. Basis for the 1991 Proposed MCL for

Uranium. In 1991, EPA proposed an MCL of

20 μg/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 × 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 × 10¥6, 1

× 10¥5 and 1 × 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 × 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 radiationprotection 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 5×10¥5

and 2×10¥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 1×10¥4 each, or 2×10¥4 combined,

assuming lifetime ingestion. The more

sophisticated model used today calculates a

risk for Ra-228 at 5 pCi/l to be 2×10¥4, and

the risk for 5 pCi/l of Ra-226 to be about

7.3×10¥5. Retaining a combined MCL at 5

pCi/L would produce the following risks

shown in Table II–2.

TABLE II–2.—MORTALITY RISK OF RADIUMS FOR CONCENTRATION COMBINATIONS AT THE MCL

Radium-226 Radium-228 Ra-226 + Ra-228

pCi/L Risk pCi/L Risk pCi/L Risk at 5 pCi/L

0 ............................................................................. 0 5 2.0×10¥4 5 2.0×10¥4

1 ............................................................................. 1.5×10¥5 4 1.6×10¥4 5 1.8×10¥4

2 ............................................................................. 2.9×10¥5 3 1.2×10¥4 5 1.5×10¥4

3 ............................................................................. 4.4×10¥5 2 8.1×10¥5 5 1.3×10¥4

4 ............................................................................. 5.8×10¥5 1 4.1×10¥5 5 9.9×10¥5

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TABLE II–2.—MORTALITY RISK OF RADIUMS FOR CONCENTRATION COMBINATIONS AT THE MCL—Continued

Radium-226 Radium-228 Ra-226 + Ra-228

pCi/L Risk pCi/L Risk pCi/L Risk at 5 pCi/L

5 ............................................................................. 7.3×10¥5 0 0 5 7.3×10¥5

b. Alpha Emitters. Both the current and

1991 proposed MCLs for alpha-emitting

radionuclides 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

2×10¥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¥4.

The current estimate of risk from

polonium-210 at 7.0 pCi/L is 1×10¥4. The

risk for radium-226 at 6.8 p/L is also 1×10¥4.

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

5.6×10¥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 5.6×10¥5

mortality are found in Table II–3.

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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, BIOSIS, 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 statisticallysignificant 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 μg/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 > 1μg/L). Twenty-four

hour and 8-hour urine samples were

collected and evaluated for uranium,

creatinine, glucose, protein, b2-microglobulin

(BMG), alkaline phosphatase (ALP), gamma

glutamyl transferase (GGT), lactate

dehydrogenase (LDH), and N-acetyl-b-Dglucosaminidase (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 Subpopulations: 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, organspecific 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 agespecific 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 III—Analytical Methods

Table III–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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TABLE III–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-particle activity, radium-226,

total radium, gross beta-particle 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 regulated radionuclide

The July 18, 1991—radionuclides rule proposed:

* Fifty-six additional methods

for compliance monitoring of

radionuclides

* Guidance for the sample handling, preservation and holding times that were cited in

the 1990 U.S.EPA ‘‘Manual

for the Certification of Laboratories Analyzing Drinking

Water’’

* The use of practical quantitation limits (PQLs) and acceptance limits as the measures of sensitivity for

radiochemical analysis

The March 5, 1997 final rule

for radionuclide methods:

* Approved 66 additional radionuclide techniques for gross

alpha-particle activity, radium-226, radium-228, uranium, cesium-134, iodine131, and strontium-90

Responded to comments regarding the analytical methods (excluding radon) received from the July 18,

1991 proposed radionuclides

rule

Updates the public on changes that have

occurred regarding radiochemical methods of analysis since the 1991 proposed

rule. The updates discussed in today’s

NODA include:

* A brief discussion of the analytical methods updates which were promulgated by

the Agency on July 18, 1997 final rule.

* Guidance for the sample handling, preservation and holding times listed in the

1997 U.S.EPA ‘‘Manual for the Certification 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 Performance 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 III–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 Preservative 1 Container 2 Maximum holding

time 3 Instrumentation 4

Gross Alpha ......................................... Concentrated HCl or HNO3 to pH <25 P or G 6 months A, B or G

Gross Beta .......................................... Concentrated HCl or HNO3 to pH <25 P or G 6 months A or G

Radium-226 ......................................... Concentrated HCl or HNO3 to pH <2 .. P or G 6 months A, B, C 6, D or G

Radium-228 ......................................... Concentrated HCl or HNO3 to pH <2 .. P or G 6 months A, B6, C 6 or G

Uranium natural ................................... Concentrated HCl or HNO3 to pH <2 .. P or G 6 months A6, F, G 6, or O

Cesium-134 ......................................... Concentrated HCl to pH <2 ................ P or G 6 months A, C or G

Strontium-89 and -90 .......................... Concentrated HCl or HNO3 to pH <2 .. P or G 6 months A or G

Radioactive Iodine-131 ........................ None .................................................... P or G 8 days A, C or G

Tritium .................................................. None .................................................... G 6 months E

Gamma/Photon Emitters ..................... Concentrated HCl or HNO3 to pH <2 .. P or G 6 months C

1 It is recommended that the preservative be added to the sample at the time of collection. It is recommended that samples be filtered if suspended or settleable solids are present at any level observable to the eye prior to adding preservative. This should be done at the time of collection. If the sample has to be shipped to a laboratory or storage area, however, acidification of the sample (in its original container) may be delayed for a period not to exceed 5 days. A minimum of 16 hours must elapse between acidification and start of analysis. 2P = 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 collection as possible. If a composite sample is prepared, a holding time cannot exceed 12 months. 4A = Low background proportional system; B = Alpha and beta scintillation system; C = Gamma spectrometer [Ge(Hp) or Ge (Li)]; D = Scintillation 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). 5 If HCl 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. 6Additional 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 shortlived 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:

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• 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. Ba133), 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. In 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 alphaemitting 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 III–3.—THE 1991 AND 1999 ESTIMATED COSTS OF ANALYSES FOR RADIONUCLIDES

Radionuclides Approximate

cost $ (1991)1

Approximate

cost $ (1999)2

Gross Alpha and beta .............................................................................................................................................. 35 45

Gross alpha—coprecip. ........................................................................................................................................... 35 45

Radium-226 ............................................................................................................................................................. 85 90

Radium-228 ............................................................................................................................................................. 100 110

Uranium (total) ......................................................................................................................................................... 45 48 (LP)

Uranium (isotopic) .................................................................................................................................................... 125 128 (AS)

Radioactive Cesium (-134) ...................................................................................................................................... 100 125

Radioactive Strontium .............................................................................................................................................. 105 144

Total Strontium (-89 and -90) .................................................................................................................................. ...... 153

Radioactive Iodine -131 ........................................................................................................................................... 100 131

Tritium ...................................................................................................................................................................... 50 60

Gamma/Photon Emitters ......................................................................................................................................... 110 142

Source:

1 56 FR 33050; July 18, 1991.

2 USEPA, 2000a.

Abbreviations: LP = laser phosphorimetry; AS = alpha spectrometry.

Note: Estimated costs are on a per-sample basis; analysis of multiple samples may have a lower cost.

21618 Federal Register / Vol. 65, No. 78 / Friday, April 21, 2000 / Proposed Rules

1Package 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 filters), they tend to require

lesser construction and engineering costs. Another

advantage is that many package plant technologies

are becoming more automated and thus can be less

demanding of operators than their fully engineered

counter-parts (EPA 1998b).

2Point-of-entry (POE) treatment units treat all of

the water entering a household or other building,

with the result being treated water from any tap.

Point-of-use (POU) treatment units treat only the

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).

D. The Detection Limits as the Required

Measures of Sensitivity

Table III–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 VARIOUS RADIOCHEMICAL CONTAMINANTS (40 CFR 141.25)

Contaminant Detection limit (pCi/L)

Gross Alpha .............. 3

Gross Beta ................ 4

Radium-226 ............... 1

Radium-228 ............... 1

Cesium-134 ............... 10

Strontium-89 .............. 10

Strontium-90 .............. 2

Iodine-131 ................. 1

Tritium ....................... 1,000

Other Radionuclides

and Photon/

Gamma Emitters.

1⁄10th 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 the1998

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 1

technologies, including those equipped with

remote control/communication capabilities,

and point-of-entry (POE)/point-of-use (POU)

versions 2 of existing technologies have

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

Federal Register / Vol. 65, No. 78 / Friday, April 21, 2000 / Proposed Rules 21619

treatment technique. Two classes of small

systems technologies are identified for future

National Primary Drinking Water Regulations

(NPDWRs): compliance technologies and

variance technologies.

Compliance technologies may be listed for

NPDWRs that promulgate MCLs or treatment

techniques. In the case of an MCL,

‘‘compliance technology’’ refers to a

technology or other means that is affordable

(if applicable) and that achieves compliance.

Possible compliance technologies include

packaged or modular systems and point-ofentry (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 technology 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–1 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 footnotes)Operator skill level required1 Raw water quality range and

considerations1

1. Ion Exchange (IE) ................................. (a) Intermediate .............................................. All ground waters.

2. Point of Use (POU) IE .......................... (b) Basic ......................................................... All ground waters

3. Reverse Osmosis (RO) ........................ (c) Advanced .................................................. Surface waters usually require pre-filtration.

4. POU RO ................................................ (b) Basic ......................................................... Surface waters usually require pre-filtration.

5. Lime Softening ...................................... (d) Advanced .................................................. All waters.

6. Green Sand Filtration ........................... (e) Basic .........................................................

7. Co-precipitation with Barium Sulfate .... (f) Intermediate to Advanced ......................... Ground waters with suitable water quality.

8. Electrodialysis/Electrodialysis Reversal .................... Basic to Intermediate ................................ All ground waters.

9. Pre-formed Hydrous Manganese Oxide

Filtration.

(g) Intermediate .............................................. All ground waters.

10. Activated alumina ............................... (a), (h) Advanced .................................................. All ground waters; competing anion concentrations may affect regeneration frequency.

11. Enhanced coagulation/filtration ........... (i) Advanced .................................................. 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 utility 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. e Removal efficiencies can vary depending on water quality.

fThis 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. gThis 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. iAssumes modification to a coagulation/filtration process already in place.

Table IV–2 lists the Small Systems

Compliance Technologies for the currently

regulated radionuclides. Technology

numbers refer to the technologies listed in

Table IV–1.

21620 Federal Register / Vol. 65, No. 78 / Friday, April 21, 2000 / Proposed Rules

TABLE IV–2.—COMPLIANCE TECHNOLOGIES BY SYSTEM SIZE CATEGORY FOR RADIONUCLIDE NPDWRS (AFFORDABILITY

NOT CONSIDERED, EXCEPT FOR URANIUM, DUE TO STATUTORY LIMITATIONS)

Contaminant

Compliance technologies1 for system size

categories (population served)

25–500 501–3,300 3,300–10,000

Combined radium-226 and radium-228 ....................................................................................... 1, 2, 3, 4, 5, 6,

7, 8, 9

1, 2, 3, 4, 5, 6,

7, 8, 9

1, 2, 3, 4, 5, 6,

7, 8, 9

Gross alpha particle activity ........................................................................................................ 3, 4 3, 4 3, 4

Total beta particle activity and photon activity, average annual concentration .......................... 1, 2, 3, 4 1, 2, 3, 4 1, 2, 3, 4

Uranium ....................................................................................................................................... 1, 2, 4, 10, 11 1, 2, 3, 4, 5,

10, 11

1, 2, 3, 4, 5,

10, 11

Note: 1 Numbers correspond to those assigned to technologies found in the table ‘‘List of Small Systems Compliance Technologies for the Currently 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; (2) 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 landcost 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 radium228 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 $3.02 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 $2.36 and

$0.73 per thousand gallons, respectively.

Unit costs are discussed in more detail in the

Technical Support Document (EPA 2000a).

EPA requests comments on its analysis of

treatment technologies, costs, and treatment

residuals disposal.

E. References

National Research Council (NRC). Safe

Water From Every Tap: Improving Water

Service to Small Communities. National

Academy Press. Washington, DC. 1997.

USEPA. Office of Drinking Water.

Suggested Guidelines for Disposal of

Drinking Water Treatment Wastes Containing

Naturally-Occurring Radionuclides (July

1990 draft).

USEPA. National Primary Drinking Water

Regulations; Radionuclides; Proposed Rule.

Federal Register. Vol. 56, No. 138, p. 33050.

July 18, 1991.

USEPA. Technologies and Costs for the

Removal of Radionuclides from Potable

Water Supplies. Prepared by Malcolm Pirnie,

Inc. July 1992.

USEPA. Office of Ground Water and

Drinking Water. Suggested Guidelines for

Disposal of Drinking Water Treatment Wastes

Containing Radioactivity (June 1994 draft).

USEPA. Announcement of Small Systems

Compliance Technology Lists for Existing

National Primary Drinking Water Regulations

and Findings Concerning Variance

Technologies. Federal Register. Vol. 63, No.

151, p. 42032. August 6, 1998. (EPA 1998a).

USEPA. ‘‘Small System Compliance

Technology List for the Non-Microbial

Contaminants Regulated Before 1996.’’ EPA–

815–R–98–002. September 1998. (EPA

1998b).

USEPA. ‘‘Actual Cost for Compliance with

the Safe Drinking Water Act Standard for

Radium-226 and Radium-228.’’ Final Report.

Prepared by International Consultants, Inc.

July 1998. (EPA 1998c).

USEPA Technologies and Costs for the

Removal of Radionuclides from Potable

Water Supplies. Draft. Prepared by

International Consultants, Inc. April, 1999.

(EPA 1999a).

USEPA. ‘‘Small System Compliance

Technology List for the Radionuclides Rule.’’

Prepared by International Consultants, Inc.

Draft. April 1999. (EPA 1999b).

USEPA. ‘‘Technical Support Document for

the Radionuclides Notice of Data

Availability.’’ Draft. March, 2000. (EPA

2000a)

Appendix V—Economics and Impacts

Analysis

A. Overview of the Economic Analysis

1. Background

Analysis of the costs, benefits, and other

impacts of regulations is required under the

Safe Drinking Water Act Amendments of

1996, Executive Order 12866 (Regulatory

Planning and Review), and EPA’s internal

guidance for regulatory development. These

Federal Register / Vol. 65, No. 78 / Friday, April 21, 2000 / Proposed Rules 21621

1The 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. 2Model 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 are described by a single set of ‘‘typical

characteristics’’ by source water type (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. 3Unit 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. 4 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 (e.g., co-treatment and pre-

/post-treatment requirements), and residuals

disposal costs and issues.

5While 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 types 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 oxygen and high

total dissolved solids, while uranium occurs at

higher levels in oxygen-rich waters with low total

dissolved solids (see the Technical Support

Document, EPA2000a).

requirements are new relative to the 1991

proposal for revisions to the existing National

Primary Drinking Water Regulations

(NPDWRs) for radionuclides.

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 μg/L; or (3) the establishment of

a uranium NPDWR with an MCL of 40 μg/

L; or (4) the establishment of a uranium

NPDWR with an MCL of 80 μg/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 radium226 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 centraltendency 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

model 1 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

systems 2,’’ compliance cost equations 3, and

the compliance action prediction model or

‘‘decision trees 4.’’ 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

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).

21622 Federal Register / Vol. 65, No. 78 / Friday, April 21, 2000 / Proposed Rules

6See the Technical Support Document (EPA

2000a) and the HRRCA (EPA 2000b). 7This analysis focuses on changes in cancer risks

from tap water ingestion. Individuals may be

exposed to radionuclides in drinking water through

other pathways (e.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. 8 ‘‘Unit risk factors and ‘‘unit risks’’ refer to the

risk per pCi/L in drinking water. They are not

estimates of cancer incidence per se, but rather are

indicators of the ‘‘potency’’ of a radionuclide. To

get 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.

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 noncompliance 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 distribution 6, 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–1.

The unit 8 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 centraltendency 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

Morbidity Mortality

Lifetime ingestionAnnual ingestionLifetime ingestionAnnual ingestion

Gross Alpha: changes in monitoring requirements (weighted average of Ra-224 and

Ra–226) ........................................................................................................................ 5.24E–06 7.48E–08 3.26E–06 4.65E–08

Gross Alpha: changes in MCL (Ra–224 only) ................................................................ 4.77E–06 6.81E–08 2.90E–06 4.15E–08

Federal Register / Vol. 65, No. 78 / Friday, April 21, 2000 / Proposed Rules 21623

9The monitoring deficiency will be corrected by

requiring the separate analysis of Ra-228 for

systems with gross alpha levels below 5 pCi/L.

TABLE V–1.—AVERAGE INDIVIDUAL RISK FACTORS, AVERAGE WATER CONSUMPTION (1.1 L/PERSON/DAY) (PER PCI/L)—

Continued

Regulatory option

Morbidity Mortality

Lifetime ingestionAnnual ingestionLifetime ingestionAnnual ingestion

Combined Radium: changes in monitoring requirements (weighted average of Ra–

226 and Ra–228) ......................................................................................................... 2.30E–05 3.28E–07 1.63E–05 2.32E–07

Combined Radium: changes in MCL (Ra–228 only) ...................................................... 2.98E–05 4.26E–07 2.12E–05 3.03E–07

Uranium: establish MCL (simple average of U–234, U–235, and U–238) ..................... 1.95E–06 2.79E–08 1.26E–06 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 radionuclides 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 $2

million ($20 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 * $5.9 million per

statistical life.

Low End Estimate: Value of fatal risk

reductions = Statistical lives saved * $1.5

million per statistical life.

High End Estimate: Value of fatal risk

reductions = Statistical lives saved * $11.5

million per statistical life.

Non-Fatal Risk Reduction Valuations

Best Estimate: Value of nonfatal risk

reductions (medical costs only) = Statistical

cases averted * $0.10 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 * $0.11 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/highestimate 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 deficiency 9 is predicted to lead

to 210 to 250 systems out of compliance with

an MCL of 5 μg/L, affecting 33,000 to 460,000

21624 Federal Register / Vol. 65, No. 78 / Friday, April 21, 2000 / Proposed Rules

persons. Implementing an MCL of 20 μg/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 μg/L is

predicted to impact 300 to 430 systems,

affecting 47,000 to 850,000 persons; 80 μg/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 bestestimate 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 μg/

L option, an assumption of an activity-tomass 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 μg/L, and 0.01 to

1 case avoided annually for an MCL of 80 μg/

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 μg/L), and less than 0.1 to 4

million dollars (80 μg/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 μg/L, and

5 to 30 million dollars for an MCL of 80 μg/

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 6560–50–U

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

BILLING CODE 6560–50–C

21626 Federal Register / Vol. 65, No. 78 / Friday, April 21, 2000 / Proposed Rules

10Table 2.4, Uncertainty Categories for Selected

Risk Coefficients. Federal Guidance Report 13

(1999).

11A 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 ranges in 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 are

appropriate (3 to 7%).

12This estimate is based on total capital costs

ranging from approximately $135,000 to $550,000

per MGD of flow. The estimate assumes typical

relationships between design and average daily

flows and a capital discount rate of 3 or 7%.

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 centraltendency 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 cancerlatency period, cancer premiums, and nonquantifiable 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

installing a new well, blending, or stopping

production from the contaminated well or

wells. The prevalence of the use of these nontreatment 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 $0.08/kgal to $0.46/kgal,

depending on system size, geologic setting,

and other site specific parameters (EPA

1999b), with an average of $0.23/kgal for

systems serving between 501 and 1,000

persons and $0.17/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

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 NonTransient Non-Community Water Systems

The available data are not sufficient to

allow EPA to predict a central-tendency

impact of the regulatory options on nontransient 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

Percent of national systems

in states with

elevated levels

(1) (percent)

Upper bound:

10% of col. (1)

(percent)

Lower bound:

1% of col. (1)

(percent)

Gross Alpha at 15 pCi/L .............................................................................................................. 60 6 1

Combined Radium at 5 pCi/L ...................................................................................................... 79 8 1

Uranium at 20 pCi/L:

Ground water ........................................................................................................................ 54 5 1

Surface water ....................................................................................................................... 29 3 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 noncommunity 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 $1 million to $4

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 $6 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 μg/L, the results suggest a range of

impacted ground water systems from 100 up

to 1,000 systems with annual costs ranging

from $1 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 μg/L ranges from less

than 10 to less than 20 systems. The

associated national annual costs for surface

water systems is less than $0.1 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 Lower Bound Estimate Upper Bound Estimate

Number of

systems out

of compliance

Annual costs

(million

dollars)

Statistical

cancer cases

avoided

(cases)

Number of

systems out

of compliance

Annual costs

(million

dollars)

Statistical cancer cases

avoided

Gross Alpha at 15 pCi/L .................................... 110 1 0.01 1,100 4 0.1

Combined Radium at 5 pCi/L ............................ 150 1 0.02 1,500 6 0.2

Uranium at 20 pCi/L:

Ground water .............................................. 100 1 <0.01 1,000 4 0.04

Surface water .............................................. < 10 0.03 <0.01 < 20 0.1 <0.01

Note: These results are based on hypothetical assumptions regarding the percent of systems likely to be out of compliance with each regulatory option as discussed in the preceding text. These are not estimates of actual compliance costs or risk reductions, and are provided for illustrative purposes only.

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 μg/L.

21628 Federal Register / Vol. 65, No. 78 / Friday, April 21, 2000 / Proposed Rules

F. References

Longtin, J.P. ‘‘Occurrence of Radon, Radium,

and Uranium in Groundwater.’’ JAWWA.

Vol. 80, No. 7, pp. 84–93. July 1988.

National Research Council. Risk Assessment

of Radon in Drinking Water. National

Academy Press. Washington, DC. 1999.

(NAS 1999).

USEPA. National Primary Drinking Water

Regulations; Radionuclides; Proposed

Rule. Federal Register. Vol. 56, No. 138, p.

33050. July 18, 1991.

USEPA. ‘‘Actual Cost for Compliance with

the Safe Drinking Water Act Standard for

Radium-226 and Radium-228—Final

Report.’’ Prepared by International

Consultants, Inc. for the Office of Ground

Water and Drinking Water. Draft. July

1998. (EPA 1998a)

USEPA. ‘‘Evaluation of Full-Scale Treatment

Technologies at Small Drinking Water

Systems: Summary of Available Cost and

Performance Data.’’ Prepared by ICF, Inc.

and ISSI, Inc. for the Office of Ground

Water and Drinking Water. December 10,

1998. (EPA 1998b)

USEPA. Results from survey of compliance

actions taken in the State of Illinois in

response to the NPDWR for combined

radium. Submitted from EPA Region 5.

1998. (EPA 1998c)

USEPA. ‘‘Guidelines for Preparing Economic

Analysis.’’ Review Draft. November 3,

1998. (EPA 1998d)

USEPA. ‘‘Regional Variation of the Cost of

Drinking Water Wells for Public Water

Supplies.’’ Prepared by Cadmus for the

Office of Ground Water and Drinking

Water. Draft. October 1999. (EPA 1999b)

USEPA. ‘‘Drinking Water Baseline Handbook:

First Edition.’’ Draft dated March 2, 1999.

(EPA 1999c)

USEPA. ‘‘Evaluation of Central Treatment

Options as Small System Treatment

Technologies.’’ Prepared by SAIC for EPA.

Draft dated January 28, 1999. (EPA 1999d)

USEPA. Cancer Risk Coefficients for

Environmental Exposure to Radionuclides,

Federal Guidance Report No. 13. US

Environmental Protection Agency,

Washington, DC, 1999. (EPA 1999e)

USEPA. ‘‘Technical Support Document for

the Radionuclides Notice of Data

Availability.’’ Draft. March, 2000. (EPA

2000a)

USEPA. ‘‘Preliminary Health Risk Reduction

and Cost Analysis: Revised National

Primary Drinking Water Standards for

Radionuclides.’’ Prepared by Industrial

Economics, Inc. for the Office of Ground

Water and Drinking Water. Draft. January

2000. (EPA 2000b)

Dated: April 7, 2000.

Charles J. Fox,

Assistant Administrator, Office of Water.

[FR Doc. 00–9654 Filed 4–20–00; 8:45 am]

BILLING CODE 6560–50–U