10274 Federal Register / Vol. 63, No. 40 / Monday, March 2, 1998 / Notices

ENVIRONMENTAL PROTECTION

AGENCY

[W–97–11; FRL–5972–5]

Announcement of the Drinking Water

Contaminant Candidate List

AGENCY: U.S. Environmental Protection

Agency (EPA).

ACTION: Notice.

SUMMARY: The Safe Drinking Water Act

(SDWA), as amended in 1996, requires

the Environmental Protection Agency

(EPA) to publish a list of contaminants

which, at the time of publication, are

not subject to any proposed or

promulgated national primary drinking

water regulation (NPDWR), that are

known or anticipated to occur in public

water systems and which may require

regulations under the SDWA [section

1412(b)(1)]. The SDWA, as amended,

specifies that EPA must publish the first

list of contaminants (Drinking Water

Contaminant Candidate List, or CCL)

not later than 18 months after the date

of enactment, i.e., by February 1998,

and every five years thereafter. The

SDWA, as amended, also specifies that

the CCL must be published after

consultation with the scientific

community, and after notice and

opportunity for public comment.

A draft CCL was published in the

October 6, 1997 edition of the Federal

Register (62 FR 52193) in order to seek

comment from the public. Seventy-one

comments were received. The

comments have been reviewed and

considered in creating the final CCL

presented in today’s notice. The CCL is

divided among contaminants which are

identified as priorities for drinking

water research, those which need

additional occurrence data, and

contaminants which are priorities for

consideration for the development of

future drinking water regulations and

guidance. The CCL includes 50

chemical and 10 microbiological

contaminants/contaminant groups.

The full record for this notice has

been established under docket number

W–97–11, and includes supporting

documentation as well as all comments

received in response to the October 6,

1997 notice. The full record is available

for inspection from 9:00 a.m. to 4:00

p.m., Monday through Friday, excluding

legal holidays at the Office of Water

Docket, East Tower Basement, USEPA

Headquarters, 401 M Street, S.W.,

Washington, D.C. For access to the

docket, please call 202–260–3027 to

schedule an appointment.

FOR FURTHER INFORMATION CONTACT: For

general information, please contact the

EPA Safe Drinking Water Hotline. The

toll-free number is 800–426–4791. The

Hotline operates from 9:00 a.m. to 5:30

p.m., Monday through Friday, excluding

legal holidays. For specific information

on the Contaminant Candidate List and

the contaminant identification process,

please contact Ms. Evelyn Washington,

at the U.S. Environmental Protection

Agency, Office of Ground Water and

Drinking Water, Mailcode 4607,

Washington, D.C. 20460, phone: 202–

260–3029, fax: 202–260–3762, email:

washington.evelyn@epamail.epa.gov.

EPA Regional Offices

I. JFK Federal Bldg., Room 2203, Boston,

MA 02203. Phone: 617–565–3602,

Jerry Healey

II. 290 Broadway, Room 2432, New

York, NY 10007–1866. Phone: 212–

637–3880, Walter Andrews

III. 841 Chestnut Street, Philadelphia,

PA 19107. Phone: 215–566–5775,

Jeff Hass

IV. 61 Forsyth Street, SW, Atlanta GA

30303. Phone: 404–562–9480,

Janine Morris

V. 77 West Jackson Blvd., Chicago, IL

60604–3507. Phone: 312–886–4239,

Kim Harris

VI. 1445 Ross Avenue, Dallas, TX

75202. Phone: 214–665–7150, Larry

Wright

VII. 726 Minnesota Ave., Kansas City,

KS 66101. Phone: 913–551–7410,

Stan Calow

VIII. One Denver Place, 999 18th Street,

suite 500, Denver, CO 80202.

Phone: 303–312–6627, Rod Glebe

IX. 75 Hawthorne Street, San Francisco,

CA 94105. Phone: 415–744–1884,

Bruce Macler

X. 1200 Sixth Avenue, Seattle, WA

98101. Phone: 206–553–1893, Larry

Worley

SUPPLEMENTARY INFORMATION:

Abbreviations Used in This Notice

AMA—American Medical Association

AWWARF—American Water Works

Association Research Foundation

CAA—Clean Air Act

CASRN—Chemical Abstract Services

Registry Number

CCL—Contaminant Candidate List

CERCLA—Comprehensive

Environmental Response,

Comprehensive and Liability Act

CPVC—Chlorinated Polyvinyl Chloride

DBPR—Microbiological and

Disinfection Byproducts Regulations

DWEL—Drinking Water Equivalent

Level

DWPL—Drinking Water Priority List

EDSTAC—Endocrine Disruptor

Screening and Testing Advisory

Committee

EPA—Environmental Protection Agency

ESWTR—Enhanced Surface Water

Treatment Rule

FIFRA—Federal Insecticide, Fungicide,

and Rodenticide Act

FQPA—Food Quality Protection Act

FR—Federal Register

GWDR—Ground Water

GW—Ground Water Disinfection Rule

IRIS—Integrated Risk Information

System

MCL—Maximum Contaminant Level

MCLG—Maximum Contaminant Level

Goal

MTBE—Methyl-t-butyl Ether

NAS—National Academy of Sciences

NAWQA—National Water Quality

Assessment Program

NDWAC—National Drinking Water

Advisory Council

NOAEL—No-Observed-Adverse-EffectLevel

NPDWR—National Primary Drinking

Water Regulations

NPL—National Priority List

NSF—National Sanitation Foundation

OPP—EPA’s Office of Pesticide

Programs

OPPTS—EPA’s Office of Pollution

Prevention and Toxic Substances

PGWDW—Pesticides in Ground Water

Database

PVC—Polyvinyl Chloride

RfD—Reference Dose

SAB—EPA’s Science Advisory Board

SAP—Science Advisory Panel

SDWA—Safe Drinking Water Act

SWTR—Surface Water Treatment Rule

TTHM—total trihalomethane

TSCA—Toxic Substances Control Act

UCMR—Unregulated Contaminant

Monitoring Regulations

WHO—World Health Organization

Table of Contents

I. Background

II. Drinking Water Contaminant Candidate

List

Table 1. Drinking Water Contaminant

Candidate List

III. Changes Made to Create the Final

Contaminant Candidate List Based on

Comments Received on the Draft

A. Acetochlor, Metolachor, and Alachlor

ESA

B. Acetone and Cumene

C. Aldicarbs and Nickel

D. Aluminum

E. Dimethoate

F. DTBB

G. Methyl Bromide

H. Microorganisms

I. MTBE

J. Organotins

K. Perchlorate

L. Rhodamine WT

M. Sodium

N. Triazines

O. Zinc

IV. Continuing Work in Preparation for

Future CCLs

A. Pesticides Deferred

B. Endocrine Disruptors
Federal Register / Vol. 63, No. 40 / Monday, March 2, 1998 / Notices 10275

C. Development of the Contaminant

Selection Process

V. Data, Research Needs and Next Steps

Table 2. Next Steps for the CCL

VI. Other Requirements

VII. References

I. Background

The Safe Drinking Water Act (SDWA),

as amended in 1996, requires the

Environmental Protection Agency (EPA)

to publish a list of contaminants that are

known or anticipated to occur in public

water systems, and which may require

regulation under the SDWA [section

1412(b)(1)]. The SDWA, as amended,

also specifies that EPA must publish

this list of contaminants (Drinking

Water Contaminant Candidate List, or

CCL) not later than 18 months after the

date of enactment (i.e., by February

1998), and publish a new CCL every five

years thereafter. The SDWA requires

that the list of contaminants include

those which, at the time of publication,

are not subject to any proposed or

promulgated national primary drinking

water regulation (NPDWR). The list

must be published after consultation

with the scientific community,

including the Science Advisory Board,

after notice and opportunity for public

comment, and after consideration of the

occurrence database established under

section 1445(g). The unregulated

contaminants considered for the list

must include, but not be limited to,

substances referred to in section 101(14)

of the Comprehensive Environmental

Response, Compensation, and Liability

Act of 1980 (CERCLA), and substances

registered under the Federal Insecticide,

Fungicide, and Rodenticide Act

(FIFRA).

Today’s notice is being published

pursuant to the requirements in section

1412(b)(1). The contaminants included

are not subject to any proposed or

promulgated national primary drinking

water regulation, are known or

anticipated to occur in public water

systems, and may require regulation

under the SDWA. During the

development of the CCL, the Agency

consulted with stakeholders, including

the National Drinking Water Advisory

Council’s (NDWAC) Working Group on

Occurrence & Contaminant Selection,

which includes microbiologists,

toxicologists, public health scientists,

and engineers, and consulted with other

members of the scientific community

including the Science Advisory Board

(SAB). A draft CCL was published in the

October 6, 1997 edition of the Federal

Register (62 FR 52193) to seek comment

from the public.

Seventy-one comments were received

in response to the notice on the draft

CCL; 66 comments were received by the

due date, and an additional 5 comments

were received later. The majority were

supportive of the CCL process and the

development of this first CCL, and

provided suggestions on specific

contaminants that should be included

on, or excluded from, the CCL. The

comments, data, and information

provided were taken into consideration

in preparing the final CCL presented in

today’s notice. Modifications to the CCL

presented in today’s notice were also

reviewed by the National Drinking

Water Advisory Council (NDWAC), and

the NDWAC Working Group on

Occurrence & Contaminant Selection.

The Agency believes the CCL

presented in today’s notice is a first step

toward improving risk assessment,

strengthening science and data, and

achieving better decision-making and

future priority setting. The CCL is

designed to be responsive to each of the

requirements noted above of the SDWA,

as amended, and is consistent with the

goals of the Drinking Water Redirection

Strategy. The CCL is the result of a

concerted effort of screening a larger set

of contaminants to a subset of those of

most concern.

This final CCL will be the primary

source of priority contaminants for the

Agency’s drinking water program. The

list is divided among priorities for

drinking water research, priorities for

additional occurrence data collection,

and those contaminants which are

priorities for consideration for Agency

determinations of whether or not to

regulate specific contaminants by

August 2001.

The SDWA does not preclude the

Agency from taking action on a

contaminant not included on the CCL.

The EPA can decide to monitor, develop

guidance, or conduct research, for a

contaminant not included on the CCL.

The Agency can also develop

regulations to address an urgent threat

to public health under SDWA [section

1412(b)(1)(D)]. The Agency is also not

precluded from modifying the CCL prior

to the due date of the next CCL, which

is February 2003.

II. Drinking Water Contaminant

Candidate List

The following table includes the

contaminants, microbiological and

chemical, presented as the Drinking

Water Contaminant Candidate List. The

chemical contaminants in the table are

identified by name and Chemical

Abstracts Service Registry Number

(CASRN). The CCL includes 50

chemical and 10 microbiological

contaminants/contaminant groups.

TABLE 1.—DRINKING WATER CONTAMINANT CANDIDATE LIST

Microbiological contaminants

Acanthamoeba (guidance expected for contact lens wearers)

Adenoviruses

Aeromonas hydrophila

Caliciviruses

Coxsackieviruses

Cyanobacteria (blue-green algae), other freshwater algae, and their toxins

Echoviruses

Helicobacter pylori

Microsporidia (Enterocytozoon & Septata)

Mycobacterium avium intracellulare (MAC)

Chemical contaminants CASRN

1,1,2,2-tetrachloroethane ..................................................................................................................................................................... 79–34–5

1,2,4-trimethylbenzene ......................................................................................................................................................................... 95–63–6

1,1-dichloroethane ............................................................................................................................................................................... 75–34–3

1,1-dichloropropene ............................................................................................................................................................................. 563–58–6

1,2-diphenylhydrazine .......................................................................................................................................................................... 122–66–7

1,3-dichloropropane ............................................................................................................................................................................. 142–28–9

1,3-Dichloropropene ............................................................................................................................................................................. 542–75–6
10276 Federal Register / Vol. 63, No. 40 / Monday, March 2, 1998 / Notices

Chemical contaminants CASRN

2,4,6-trichlorophenol ............................................................................................................................................................................ 88–06–2

2,2-dichloropropane ............................................................................................................................................................................. 594–20–7

2,4-dichlorophenol ................................................................................................................................................................................ 120–83–2

2,4-dinitrophenol .................................................................................................................................................................................. 51–28–5

2,4-dinitrotoluene ................................................................................................................................................................................. 121–14–2

2,6-dinitrotoluene ................................................................................................................................................................................. 606–20–2

2-methyl-Phenol (o-cresol) ................................................................................................................................................................... 95–48–7

Acetochlor ............................................................................................................................................................................................ 34256–82–1

Alachlor ESA & other acetanilide pesticide degradation products ...................................................................................................... N/A

Aldrin .................................................................................................................................................................................................... 309–00–2

Aluminum ............................................................................................................................................................................................. 7429–90–5

Boron ................................................................................................................................................................................................... 7440–42–8

Bromobenzene ..................................................................................................................................................................................... 108–86–1

DCPA mono-acid degradate ................................................................................................................................................................ 887–54–7

DCPA di-acid degradate ...................................................................................................................................................................... 2136–79–0

DDE ..................................................................................................................................................................................................... 72–55–9

Diazinon ............................................................................................................................................................................................... 333–41–5

Dieldrin ................................................................................................................................................................................................. 60–57–1

Disulfoton ............................................................................................................................................................................................. 298–04–4

Diuron .................................................................................................................................................................................................. 330–54–1

EPTC (s-ethyl-dipropylthiocarbamate) ................................................................................................................................................. 759–94–4

Fonofos ................................................................................................................................................................................................ 944–22–9

Hexachlorobutadiene ........................................................................................................................................................................... 87–68–3

p-Isopropyltoluene (p-cymene) ............................................................................................................................................................ 99–87–6

Linuron ................................................................................................................................................................................................. 330–55–2

Manganese .......................................................................................................................................................................................... 7439–96–5

Methyl bromide .................................................................................................................................................................................... 74–83–9

Methyl-t-butyl ether (MTBE) ................................................................................................................................................................. 1634–04–4

Metolachlor ........................................................................................................................................................................................... 51218–45–2

Metribuzin ............................................................................................................................................................................................. 21087–64–9

Molinate ................................................................................................................................................................................................ 2212–67–1

Naphthalene ......................................................................................................................................................................................... 91–20–3

Nitrobenzene ........................................................................................................................................................................................ 98–95–3

Organotins ........................................................................................................................................................................................... N/A

Perchlorate ........................................................................................................................................................................................... N/A

Prometon ............................................................................................................................................................................................. 1610–18–0

RDX ..................................................................................................................................................................................................... 121–82–4

Sodium ................................................................................................................................................................................................. 7440–23–5

Sulfate .................................................................................................................................................................................................. 14808–79–8

Terbacil ................................................................................................................................................................................................ 5902–51–2

Terbufos ............................................................................................................................................................................................... 13071–79–9

Triazines & degradation products of triazines (including, but not limited to Cyanazine 21725–46–2, and atrazine-desethyl 6190–

65–4).

Vanadium ............................................................................................................................................................................................. 7440–62–2

III. Changes Made to Create the Final

Contaminant Candidate List Based on

Comments Received on the Draft

The criteria which EPA used to select

the contaminants for the CCL are

described in detail in the October 6,

1997 notice (62 FR 52193) on the draft

CCL. In general, the criteria for

including a contaminant on the CCL

consisted of determinations of whether

the occurrence, or anticipated

occurrence, of a contaminant was likely

at levels of concern to human health.

The October notice solicited input from

the public and specifically requested

comments on (1) the approach EPA used

to create the list and suggestions on the

process for future lists; (2) contaminants

on the list; (3) data needs categories; and

(4) whether to include perchlorate on

the CCL.

EPA received 71 comments, 66 by the

deadline and 5 additional late

comments. The majority of comments

were supportive of the CCL process, and

the development of this first CCL.

Comments were received from a number

of segments of the stakeholder

community, including equipment

manufacturers, consultants, chemical

manufacturers, trade associations,

environmental groups, state regulatory

agencies, water utilities, and private

citizens. Commenters provided data and

information on specific contaminants

and included suggestions on the process

for future CCL development, as well as

feedback on the data and research needs

indicated for the contaminants on the

CCL. Roughly 60 issues were raised by

the comments, both contaminantspecific and related to the development

of a process for identifying

contaminants for future CCLs. The

comments, data, and information

provided were taken into consideration

in preparing the final CCL presented in

today’s notice. Proposed changes to the

CCL were also reviewed by the NDWAC

Working Group on Occurrence &

Contaminant Selection, and the

NDWAC full-Council.

A number of comments indicated that

many did not understand the function

of the CCL. The CCL is not the list of

contaminants for which the Agency has

made a determination to regulate. The

CCL is a list of priority contaminants

(not otherwise addressed) for drinking

water program activities which include

those for: (1) drinking water research,

(2) monitoring, (3) guidance

development, as well as those for (4)

selection and regulatory determination

by the year 2001. The next steps likely

to occur with regard to any given

contaminant are discussed in more

detail in Section V in today’s notice.

Despite the support expressed for the

development of this first CCL,

commenters advised that more robust

criteria are needed for future CCL
Federal Register / Vol. 63, No. 40 / Monday, March 2, 1998 / Notices 10277

development and for contaminant

selection. The Agency agrees with these

commenters and will continue to work

to develop a contaminant identification

process for chemical and

microbiological contaminants to be used

to develop future CCLs. Section IV.C. of

today’s notice provides additional

information on how the Agency plans to

develop these processes.

The following is a summary of the

significant public comments received

that led to changes to the CCL. The

remainder of this section responds to

the more significant comments, and

indicates how the CCL was changed in

response to these comments. A

complete report of responses to all

comments received on the notice of the

draft CCL can be found in the docket.

A. Acetochlor, Metolachor, and

Alachlor ESA

A number of commenters supported

the inclusion of acetochlor, metolachor,

and alachlor ESA (the sulfonic acid

degradate of alachlor) on the CCL, while

others indicated that they should not be

included. Three commenters indicated

that acetochlor should have low priority

for regulation, and that the Agency

should consider deleting it from the

CCL. The commenters argued that under

the Acetochlor Registration Project, the

EPA has established very conservative

triggers for its potential cancellation of

use as a pesticide. The commenters

went on to indicate that in 175

community water systems monitored

since March 1995, acetochlor detections

have occurred in only 20% of samples,

that no system had an average mean

concentration exceeding 2 ppb, which is

one of the triggers, and that additional

monitoring data will indicate that

concentrations found in public water

systems are far below 140 ppb.

One commenter argued that

metolachlor should not be included on

the CCL. That although it is detected in

water, it is rarely above the lifetime

health advisory level of 70 ppb, and the

detections in most cases are associated

with point sources. The commenter

stated that data collected under the

Unregulated Contaminant Monitoring

Regulations is available on a state-bystate basis, and the results reported from

3 States also indicate no detections

above the lifetime health advisory level

of 70 ppb. Another commenter

suggested that alachlor ESA should not

be included on the CCL, as it, too,

should have a low priority for regulation

based on concentrations in water not

exceeding 6370 ppb.

Other commenters argued that

metolachor, acetochlor, and alachlor

ESA should be kept on the CCL since

States reported finding these

contaminants in water. One commenter

added that the metolachor ESA and

metolachor OA degradation products

should be included on the CCL also,

since all have been found in ground

water.

One commenter also pointed out that

metolachlor, acetochlor, and alachlor do

not have a common mode of action, and

thus cannot be grouped together to

develop a single standard to address all

acetanilide pesticides.

EPA Response

The Agency disagrees with the

commenters who believe it is

inappropriate to include acetochlor,

metolachor, and alachlor ESA on the

CCL. By including these contaminants

on the CCL, the Agency has not yet

made a determination with respect to

regulating any of them. In light of the

reported occurrences of these

contaminants in water, the drinking

water program needs to determine what

action is appropriate to ensure the

protection of public health even if the

action may be only the development of

guidance for States and public water

systems. The Office of Water will

evaluate further the available toxicity

and occurrence information for these

pesticides in order to determine

appropriate concentration values

adequate to protect against risks

associated with exposure through

drinking water. With respect to

metolachlor specifically, the Agency

believes it is appropriate to include it on

the CCL. The data collected under the

Unregulated Contaminant Monitoring

Regulations is being collected from all

States and will be compiled and

evaluated as additional information is

collected and evaluated for all

contaminants on the CCL.

The Agency agrees that it is

appropriate to include other acetanilide

pesticide degradation products in

addition to alachlor ESA, since they,

too, have been found in ground water.

However, at this time, the Agency has

not yet determined which are the most

important to include; therefore, EPA has

decided to include alachlor ESA & other

acetanilide pesticide degradation

products as a group of contaminants on

the CCL. The determination of which

degradation products are of most

concern will be determined as we learn

more about these contaminants as a

class. The Agency also agrees with the

commenter that because alachlor,

acetochlor, and metolachlor do not have

a common mode of action, they are not

at this time appropriate contaminants to

be grouped together to develop a single

approach addressing all acetanilide

pesticides. Contrary to earlier

statements, acetanilide pesticides are

not likely candidates for development of

‘‘total standards’’ in the foreseeable

future. However, the Agency is

interested in the development of ‘‘total

standards,’’ or standards that address

classes of compounds, where

appropriate, and as the state of the

science improves.

B. Acetone and Cumene

Two commenters remarked that

outdated oral reference doses (RfD) from

the Integrated Risk Information System

(IRIS) for acetone and cumene were

used in developing the draft CCL and

that analyses should be done with

current information. The Chemical

Manufacturers Association’s Acetone

Panel submitted comments about

acetone and recommended that it

should not be included on the final

CCL. The reason given, in addition to

the outdated RfD, was that outdated

information concerning levels of

acetone detected in the environment,

including data from old National

Priority List (NPL) sites had been used

in the Agency’s evaluation and that this

did not provide a reliable basis for

estimating likely levels of acetone in

drinking water or sources of drinking

water. The Panel believes more relevant

information shows that acetone is

unlikely to be present in drinking water

or sources of drinking water at levels of

concern.

The Chemical Manufacturers

Association’s Cumene Panel submitted

comments about cumene and

recommended that it should not be

included on the final CCL. The reason

given, in addition to the outdated RfD,

was that concentrations of cumene

detected in the environment were not at

levels of concern, and it is rarely

detected in drinking water or sources of

drinking water.

EPA Response

The Agency agrees with the

commenters that the current IRIS values

should be used in the evaluations for

developing the CCL. The updated value

for acetone has not been posted on the

IRIS database; however, the Agency has

acknowledged the new value of 0.9 mg/

kg/day previously in a notice

concerning section 313 of the

Emergency Planning and Community

Right-to-Know Act (60 FR 31644). The

updated value for cumene has been

posted on the IRIS database, and is 0.1

mg/kg/day.

The occurrence data from the U.S.

Geological Survey’s National Water

Quality Assessment Program (NAWQA)

indicates that acetone was detected at a
10278 Federal Register / Vol. 63, No. 40 / Monday, March 2, 1998 / Notices

frequency of greater than 10% of the

samples collected; however, the

concentrations found did not exceed

their reporting level of 0.2 μg/l. When

the current IRIS values are used for

acetone and cumene, and compared to

the available occurrence data, neither

meets the criteria set forth for

identifying contaminants for the CCL,

and therefore, acetone and cumene have

been removed from the CCL.

C. Aldicarbs and Nickel

EPA received a number of comments

encouraging the inclusion of aldicarbs

and nickel on the CCL, while a few

commented that it was inappropriate to

include these contaminants, despite the

Agency’s existing statutory obligation

with regard to these contaminants.

EPA Response

In the case of aldicarbs (aldicarb,

aldicarb sulfoxide, aldicarb sulfone) and

nickel, the Agency has determined that

it is inappropriate to include these

contaminants on the CCL. The 1996

Amendments to SDWA explicitly

reenacted the requirements for

regulation of these contaminants

[section 1412 (b)(2)]. In response to an

administrative petition from the

manufacturer Rhone-Poulenc, the

Agency issued an administrative stay of

the effective date of the maximum

contaminant levels (MCLs) for aldicarbs,

and they never became effective.

NPDWRs for nickel were promulgated

on July 17, 1992, but the MCL was later

vacated and remanded in response to a

lawsuit from the Nickel Development

Institute and other industry parties.

The Agency intends to complete

regulatory action for both aldicarbs and

nickel. The time-frame of completing

action for these contaminants is likely to

be the same time-frame required by

SDWA for regulatory determinations for

contaminants on the CCL. When

considering the nature and type of work

necessary to complete action on these

contaminants, the effort for aldicarbs is

anticipated to be less extensive than that

required for nickel; thus, regulations for

aldicarbs are likely to be completed

prior to regulations for nickel.

D. Aluminum

EPA received four comments

recommending that aluminum not be

included on the CCL. One commenter

stated that regulations would be

premature at this time, due to the need

for additional information on the risk of

adverse effects and occurrence in

drinking water. Other commenters

argued that there was no scientific

health basis for the inclusion of

aluminum on the CCL, and that the

World Health Organization (WHO)

stated in 1995 that there is an

inadequate basis for revising existing

guidelines for aluminum below the 200

μg/l standard used to control taste and

odor effects. The commenters also

explained that the source of aluminum

in drinking water is primarily linked to

the use of alum as a flocculent in water

treatment, and the implications of

regulating aluminum at lower levels

could cause deleterious effects on water

quality.

An additional commenter felt that

aluminum should be included on the

CCL based on new literature on the

relationship of aluminum to

Alzheimer’s Disease, elderly mental

impairment, and childhood learning

disabilities. The commenter disagreed

with the need for additional data on the

health impacts of aluminum. The

commenter contends that much more is

actually known today about how

aluminum causes neurological injury

than is known for lead, and that there

is as much data on the health effects of

aluminum as was ever available for

lead.

EPA Response

The Agency disagrees with the

commenters who indicated that

aluminum should not be on the CCL.

The Agency believes it is appropriate to

include aluminum on the CCL because

of the new developments and research

on aluminum epidemiology indicating a

potential link between aluminum and

adverse neurological effects. It is clear

that additional studies are needed to

characterize the risk of this contaminant

from exposure through drinking water.

Due to aluminum’s widespread

occurrence and the recent studies

indicating some association with

Alzheimer’s like symptoms and other

potential neurotoxic effects, the Agency

believes aluminum warrants further

investigation. It is also EPA’s opinion

that additional data are needed to

determine an adequate no-observedadverse-effect-level (NOAEL) for

potential chronic neurotoxicity. The

inclusion of a contaminant on the CCL

does not necessarily mean that the

contaminant will be regulated.

Contaminants on the CCL include those

priorities for which the Agency must

make a determination of whether or not

to regulate by the year 2001, and

priority contaminants for which the

Agency will gather additional data and

conduct research. At this time, the EPA

has included aluminum among the

contaminants for which additional

research is needed.

E. Dimethoate

One commenter suggested that

dimethoate be deleted from the CCL.

The major reasons given were that

dimethoate did not meet the occurrence

criteria, because data used in the

Agency’s analysis from the Pesticides in

Ground Water Database (PGWDB) report

were recorded erroneously, and that the

IRIS values lack critical evaluation and

therefore should not be considered in

evaluating whether a contaminant

should be included on the CCL.

EPA Response

The Agency agrees with the

commenter on the point raised about the

occurrence data, but not on the point

raised about the use of IRIS values.

Based on the faulty occurrence data,

dimethoate has therefore been removed

from the CCL.

In general, the RfD is an estimate

(with uncertainty spanning perhaps an

order of magnitude) of a daily exposure

to the human population (including

sensitive subgroups) that is likely to be

without an appreciable risk of

deleterious effects during a lifetime. The

health assessment information and RfD

values on a chemical substance are

included in IRIS only after a

comprehensive review of chronic

toxicity data by U.S. EPA health

scientists from several program offices

and the Office of Research and

Development. The Agency believes it is

entirely appropriate to use RfD values

reported to IRIS in the absence of

drinking water health advisory values in

the derivation of health levels of

concern for determining if a

contaminant should be included on the

CCL.

However, according to EPA’s Office of

Pesticide Programs (OPP), the office that

prepared the PGWDB report, and the

Georgia Department of Natural

Resources, the data reported for the

State of Georgia are incorrect. The

laboratory analysis sheets from the

Georgia Ground Water Management

Laboratory Program indicate dimethoate

was not detected in any samples in the

State. By eliminating the occurrence

data from the PGWDB report for the

State of Georgia and replacing it with

this new information, which the Agency

feels is appropriate, dimethoate no

longer meets the criteria for inclusion

on the CCL, and has therefore been

removed.

F. DTBB

DTBB, also known as 2,6-di-tert-butylp-benzoquinone, is a contaminant that

appears to be associated with sewage

contamination of ground water, and is
Federal Register / Vol. 63, No. 40 / Monday, March 2, 1998 / Notices 10279

considered by some to be a good

indicator of such contamination. DTBB

was determined not to meet the criteria

for the CCL per se, but was included on

the draft list nevertheless, because of the

persistent nature of the contaminant,

and its potential to serve as an indicator.

One commenter stated that coliforms

and nitrate already serve the purpose as

indicators of contamination, and that it

was pointless to include DTBB on the

CCL, since it, in fact, did not meet the

criteria.

EPA Response

The Agency agrees with the

commenter and has removed DTBB

from the CCL. DTBB does not meet

criteria set forth for identifying

contaminants for the CCL, and since

there are currently acceptable indicators

of sewage contamination in the use of

total coliforms, its inclusion is

unnecessary.

G. Methyl Bromide

Several commenters supported the

inclusion of methyl bromide on the

CCL. The principal reason cited by

commenters was the widespread use of

methyl bromide as a fumigant and its

likely occurrence in drinking water

sources. One commenter indicated that

although the frequency of detection in

samples was less than 0.1% in ambient

water monitoring conducted by the U.S.

Geological Survey, methyl bromide

should be considered for inclusion

because the environmental significance

may warrant it.

EPA Response

Methyl bromide, which is also known

as bromomethane, was included on the

draft CCL based on input from

stakeholders that it was found in

drinking water. In response to the

comments, EPA has reevaluated the

available information on methyl

bromide occurrence. Contrary to

assertions of likely widespread

occurrence in source water due to its

use as a fumigant, the U.S. Geological

Survey ambient water monitoring

indicates it occurs at less than 0.1%

frequency, at very low concentrations

(less than 0.2 μg/l). However,

unregulated contaminant monitoring

data collected from States indicates

methyl bromide occurred in 0.8% of the

public water systems. One explanation

for this apparent anomaly could be that

the finished water occurrence comes not

from its use as a fumigant, but that

methyl bromide is associated with the

disinfection processes used for drinking

water treatment. Nevertheless, methyl

bromide met the criteria for inclusion

on the CCL; the concentrations reported

(maximum 29 μg/l) in the unregulated

contaminants database exceeded the

health level of 0.8 μg/l.

Methyl bromide is a gas produced by

both manmade and natural sources.

Methyl bromide is primarily used for

soil fumigation (87%), but its other

agricultural uses include: commodity

and quarantine treatment (8%), and

structural fumigation (5%). When used

as a soil fumigant, methyl bromide is

injected into the soil at a depth of 12 to

24 inches. About 50 to 95% of the

methyl bromide injected in the soil

eventually enters the atmosphere. About

80 to 95% of the amount used for

commodity treatments, and well over

90% used for structural fumigation

eventually enters the atmosphere. A

significant quantity of methyl bromide

used for agricultural purposes is known

to escape to the atmosphere due to its

volatile nature. Therefore, the U.S.

Geological Survey data indicating less

than 0.1% frequency of occurrence is

consistent with what would be expected

to present in ground water due to

methyl bromide’s use as a fumigant.

Methyl bromide is also considered a

Class I ozone depleting substance, and

as such, its use is being phased out

around the world by the Montreal

Protocol, and in the U.S., by the Clean

Air Act (CAA). The Montreal Protocol is

an international treaty developed to

protect the earth from the detrimental

effects of ozone depletion, and to

control the production and trade of

ozone depleting substances on a global

basis. Title VI of the CAA, as amended

in 1990, requires that certain ozone

depleting substances be phased out in

the U.S. within seven years. Under the

CAA, the EPA has prohibited the

production and importation of methyl

bromide starting January 1, 2001. As a

result, given methyl bromide’s lack of

persistence, occurrence in source waters

will likely decrease even more.

If methyl bromide is a disinfection

byproduct, EPA has a number of rules

and activities currently in place and

under development to address it. In

1979, EPA issued an NPDWR

establishing an MCL for the total

trihalomethanes (TTHMs) disinfection

byproducts. The Agency is also in the

process of updating the disinfection

byproducts regulation. In 1994, EPA

proposed a revised standard for TTHMs

and a new standard for haloacetic acids.

The TTHMs were regulated not only to

control trihalomethanes, but also to

protect against other similar byproducts.

Because of structural similarity, steps to

reduce formation of TTHMs would also

reduce formation of methyl bromide.

The treatment technique of enhanced

coagulation, included in the 1994

proposed DBPR, will remove

disinfection byproduct precursors, thus

reducing the levels of disinfection

byproducts in finished waters. Although

methyl bromide is not a TTHM, for

which an MCL is explicitly established,

the Agency believes it would be

effectively controlled under the DBPR.

However, it is not clear whether methyl

bromide is being formed due to

disinfection.

Because it cannot be determined

whether methyl bromide is being

formed due to disinfection, and its use

as a fumigant cannot be completely

dismissed as source of drinking water

contamination, the Agency has decided

to retain methyl bromide on the CCL. At

the January 7, 1998 meeting, the

NDWAC Working Group on Occurrence

& Contaminant Selection concurred

with the EPA recommendation to delete

methyl bromide because it was being

addressed in ongoing rulemakings for

disinfection byproducts. However, at

the February 2, 1998 meeting, the full

NDWAC recommended the Agency

retain methyl bromide on the CCL after

receiving comment that because it is a

mono-halogenated compound, it was

not specifically regulated with the

TTHM family which are tri-halogenated

compounds, and that it may not turn out

to be a disinfection byproduct. At the

meeting, EPA was insufficiently lucid in

explaining the connection between the

TTHM byproducts and the control of

similar byproducts. Nonetheless, after

further consideration of the NDWAC

recommendation, and given the

uncertainties about the source, EPA has

concluded that methyl bromide should

remain on the CCL.

Since methyl bromide is a gas, most

health studies have used the inhalation

route of exposure, and the effects of oral

exposure have received limited

attention. In 1989, EPA classified

methyl bromide as a Group D

carcinogen (not classifiable) due to

inadequate bioassay data. At the time of

the IRIS assessment, also in 1989, a

chronic oral study was not available,

therefore an additional uncertainty

factor of 10 (total uncertainty of 1,000)

was applied to the RfD calculation.

However, since the IRIS assessment, a 2-

year rat feeding study showed no

evidence of carcinogenicity, and a

National Toxicology Program inhalation

study, conducted in 1992, found no

evidence of carcinogenicity. The Agency

will also explore the potential sources of

drinking water contamination, and the

expected impact of the prohibited

production and importation of methyl

bromide which begins in January 1,

2001. Methyl bromide is listed on the

Research Priorities portion of the CCL to
10280 Federal Register / Vol. 63, No. 40 / Monday, March 2, 1998 / Notices

allow the Agency time to better

determine the drinking water risk due to

this contaminant.

H. Microorganisms

Many commenters stated that the

rationale for the inclusion of

microorganisms appeared to be

inconsistent. They suggested that other

microorganisms would have been

included had the criteria been used

consistently. It was not the intention of

EPA, nor the participants of the EPA

Drinking Water Microbiology and Public

Health Workshop, to develop a

comprehensive list of all possible agents

of waterborne disease. The intent was to

list what were considered the most

important agents (or potential agents) of

waterborne disease. The Agency

recognizes that the Workshop

participants could have established

different lists of reasonable criteria for

selecting pathogens, and believes that

the ultimate decisions represent the best

(albeit sometimes subjective) judgment

of the panel. Nevertheless, the Agency

believes that the process for developing

the current CCL for microorganisms by

this group of nationally recognized

experts in the field of microbiology was

reasonable and credible.

EPA believes that regulations that are

currently in effect [Surface Water

Treatment Rule (SWTR), Total Coliform

Rule (TCR)] or are now under

development [e.g., Groundwater

Disinfection Rule (GWDR), Enhanced

Surface Water Treatment Rule (ESWTR),

and Disinfection Byproducts

Regulations (DPBR)] will address a

number of the microorganisms that

commenters have suggested. Generally,

if a microorganism has not caused, or

not expected to cause, a waterborne

outbreak in the U.S., or if the organism

is known to be susceptible to

disinfection or filtration required by

current or upcoming regulations, the

organism has not been included on the

CCL.

Protozoa

Several commenters supported the

draft CCL, which included Toxoplasma

gondii, Cyclospora cayetanensis, and

two microsporidia—Enterocytozoon and

Septata. One commenter suggested the

addition of Entamoeba histolytica to the

CCL, primarily because of its virulence.

One commenter suggested that EPA add

Isospora belli to the final CCL.

EPA Response

After further consideration, EPA has

decided to remove Toxoplasma and

Cyclospora from the final CCL.

Toxoplasma gondii is about the same

size as Giardia, and Cyclospora

cayetanensis is larger than

Cryptosporidium. The Agency believes

that the upcoming M/DBPR to control

Giardia and Cryptosporidium will also

control these larger organisms.

Microsporidia remains on the CCL for

the reasons indicated in the preamble to

the draft CCL, including the

ineffectiveness of chlorination and

filtration.

The Agency recognizes that

Entamoeba histolytica can be virulent.

Even though the commenter cites an

article stating that dogs and perhaps

pigs may be reservoirs for E. histolytica

(Benenson 1995), animals are probably

not major host reservoirs, in contrast to

the situation for Giardia and

Cryptosporidium. Thus, if sewage

treatment practices are adequate, the

potential for source water

contamination is probably low, as

suggested by the fact that the organism

has not caused a significant waterborne

disease outbreak since the early 1950s

(the one reported exception in the U.S.

was a small outbreak in 1984 associated

with untreated well water). Importantly,

the cyst is large (10–15μm). It is slightly

larger than a Giardia cyst, and much

larger than microsporidia spores that

infect humans (1–5μm) to which the

commenter compares E. histolytica.

Thus, EPA believes that regulations that

control for Giardia and Cryptosporidium

should also control E. histolytica. For

these reasons, E. histolytica was not

included on the final CCL. The Agency

has also decided not to include Isospora

belli for the reasons given in the

preamble of the draft CCL, especially for

the fact that its oocysts are 30×12μm,

larger than Giardia cysts, and any rule

to control Giardia and Cryptosporidium

should also control this organism.

Viruses

The draft CCL included the following

viruses: caliciviruses, adenoviruses,

coxsackieviruses, echoviruses, and the

hepatitis A virus. Several commenters

suggested that EPA add rotaviruses,

hepatitis E virus, and bacteriophage to

the final CCL.

EPA Response

The final CCL remains the same as the

draft, except that the hepatitis A virus

has been removed. Hepatitis A was

removed because it is being addressed

by current regulations, or regulations

under development. As a matter of

policy, all viruses are regulated as a

class under EPA’s SWTR and are going

to be regulated as a class under the

GWDR, and the Agency does not believe

that additional research is needed to

demonstrate the efficacy of disinfection

for this organism. In contrast, the

Agency believes that additional research

is needed on the impact of treatment for

the other viruses that remain on the

CCL.

EPA did not include rotaviruses on

the final CCL, primarily because they

are vulnerable to disinfection and

should always be associated with fecal

contamination. Thus, the Agency

believes that EPA’s SWTR, plus the

upcoming GWDR, should adequately

control these viruses.

EPA excluded the hepatitis E virus

from the final CCL because the Agency

does not regard the virus as a significant

public health threat in the U.S. and

believes that current sewage treatment

practices are sufficient to eliminate

significant risk of waterborne

transmission. EPA recognizes that

hepatitis E is a major problem in some

developing countries, especially for

pregnant women. However, there is no

evidence that the organism is a problem

in the U.S. Rare cases have occurred in

the U.S., usually among travelers

returning from an area where the

disease is endemic (Mast and

Krawczynski 1996). Structurally, the

organism is a small, single-stranded

RNA virus similar to the caliciviruses,

coxsackieviruses, and echoviruses, all of

which remain on the CCL, because of

evidence of outbreaks and occurrence in

finished waters.

Bacteriophage were excluded from the

CCL because they are not pathogenic to

humans. However, EPA recognizes that

they may be useful as an indicator of

fecal contamination. EPA has decided

not to include indicators of fecal

contamination or of pathogens on the

final CCL. However, the Agency will

consider indicators in the context of

regulations to control pathogens on the

CCL. For example, the Agency is

considering two bacteriophage—the

somatic coliphage and the male-specific

coliphage—as an indicator of fecal

contamination under the Groundwater

Disinfection Rule.

Bacteria

The draft CCL included the following

bacteria: Helicobacter pylori, Legionella,

Mycobacterium avium complex, and

Aeromonas hydrophila. Commenters

urged EPA to include additional

bacteria, including Pseudomonas

aeruginosa, Shigella, Salmonella,

Vibrio, Arcobacter, Campylobacter,

Yersinia, and E. coli O157:H7, and that

if these enteric bacterial pathogens were

not included on the CCL, then H. pylori

and A. hydrophila should not be

included either, because both are

sensitive to disinfection also.
Federal Register / Vol. 63, No. 40 / Monday, March 2, 1998 / Notices 10281

EPA Response

The final CCL does not include the

enteric bacterial pathogens that

commenters suggested EPA add

(Shigella, Salmonella, Vibrio,

Arcobacter, Campylobacter, Yersinia,

and E. coli O157:H7). The Agency’s

reasons for excluding these organisms

are that they are all sensitive to

disinfection and are all associated with

fecal contamination. Thus, EPA regards

total coliforms as an adequate indicator

for these organisms. Moreover, the

SWTR requires all surface water systems

to disinfect, and the forthcoming GWDR

is likely to require systems that have

wells vulnerable to fecal contamination

to disinfect or provide other corrective

action. The Agency regards these

regulatory tools as sufficient to control

for the above pathogens.

With regard to P. aeruginosa, the

preamble to the draft CCL indicated that

the participants of the EPA Drinking

Water Microbiology and Public Health

Workshop could not agree on whether

to include this organism on the draft

CCL. There was controversy among

participants about its public health

significance and its potential health risk

via the waterborne route. Therefore,

participants recommended that EPA

conduct a complete literature search on

the topic before deciding whether to

include this organism on the final list.

The Agency has not yet completed this

search. Because of this lack of

information, EPA has decided to defer a

decision on P. aeruginosa and not

include it on the CCL. However, should

the literature search suggest that

regulatory action may be necessary, EPA

will increase the priority of research in

this area, if appropriate.

With regard to Helicobacter, following

the meeting of the panel, an article was

published indicating that Helicobacter

is sensitive to chlorine (Johnson, Rice

and Reasoner 1997). However, EPA

decided not to remove Helicobacter

from the CCL because of the large

number of people in the U.S. affected by

peptic ulcers (about 20 million people)

and gastritis, the poor survival rate of

individuals with gastric cancer, and

ignorance about the mode of

transmission of the organism.

Helicobacter pylori has been implicated

in the cause of these three diseases. The

Agency believes that, in spite of the

recent disinfection data, it would be

improper to remove Helicobacter from

the CCL for these reasons.

With regard to Aeromonas

hydrophila, EPA recognizes that this

organism is sensitive to disinfection in

source and finished waters. However,

unlike the fecal pathogens listed above,

A. hydrophila may enter the distribution

system either as a result of inadequate

treatment or a break in the water

distribution system, and grow as part of

the biofilm on the pipes or in the

sediment, which may protect it from

disinfectants. In addition, A. hydrophila

is not necessarily associated with fecal

contamination. Thus, the total coliforms

rule may not be adequate as an indicator

for this organism. Moreover, systems

which are not required to disinfect (or

take other corrective action) under the

forthcoming Groundwater Disinfection

Rule because they are considered not

vulnerable to fecal contamination, may

still be vulnerable to A. hydrophila. For

these reasons, EPA does not believe that

this organism can be treated in the same

manner as E coli O157:H7 and other

fecal bacteria listed by the commenter.

Thus, the final CCL includes A.

hydrophila .

EPA removed Legionella in ground

water from the final CCL. It was

removed because: (1) the Agency

intends to address the control of this

organism under the Groundwater

Disinfection Rule, and (2) the Agency

does not believe that high priority

research is needed in this area to

regulate this organism.

Algae and Their Toxins

Several commenters strongly urged

EPA to add algae, especially the bluegreen algae, plus their toxins (e.g.,

mycotoxin) to the CCL. One commenter

suggested that Pfiesteria piscicida be

included on the final CCL, as well.

EPA Response

In the preamble to the draft CCL, EPA

stated that certain species of blue-green

algae produce toxins that could be

harmful if ingested at high enough

concentrations, but that algal control

was best handled through good

watershed management practices. The

Agency continues to regard this strategy

as reasonable. However, the Agency has

decided to add the algae and their

toxins to the final CCL because: (1)

pathogenic algae and their toxins are not

necessarily associated with fecal

contamination and thus may not be

effectively controlled by the SWTR or

ESWTR, and (2) some data suggest that

current treatment techniques may be

particularly inadequate in controlling

algal toxins. Placement of this group of

contaminants on the CCL will make

them a priority for research to determine

what triggers toxic algal growth in

source water and the effectiveness of

water treatment practices.

EPA is aware that Pfiesteria piscicida

has been implicated in adverse health

effects in humans. Apparently at least

13 researchers who worked with dilute

toxic cultures of this organism and 10

fishermen sustained mild to serious

health effects by water contact or by

inhaling toxic aerosols. Symptoms

include skin rashes, reddening of the

eyes, severe headaches, blurred vision,

nausea/vomiting, breathing difficulties,

kidney and liver problems, short-term

memory loss, confusion, and other

problems. The organism has a

complicated life cycle, with about 24

stages. Pfiesteria’s habitat is estuarine or

brackish water. Current data indicate

that, like most other dinoflagellates, the

organism grows poorly in fresh water

and does not elaborate toxins in this

milieu, thus, there is no evidence that

Pfiesteria occurs or could occur in

drinking water. Moreover, the size

ranges from 5–450 μm, with the

dormant cyst stages 7–60 μm in

diameter. Thus filtration that is effective

for removing Cryptosporidium (4–6 μm)

should be effective for removing

Pfiesteria. For these reasons, EPA

believes that Pfiesteria does not

represent a health threat in drinking

water systems, and thus did not include

Pfiesteria on the final CCL.

I. MTBE

A number of commenters agreed with

the inclusion of methyl-t-butyl ether

(MTBE) on the CCL, and some indicated

that MTBE should be included among

the contaminants for which

determinations will be made by 2001.

Another commenter suggested it should

not be included on the CCL but should

be included in the forthcoming

Unregulated Contaminant Monitoring

rulemaking, due in 1999.

EPA Response

The Agency agrees that MTBE should

remain on the CCL. However, as with all

the contaminants on the list, EPA has

not made a determination with respect

to regulating MTBE. Although there are

serious limitations in the MTBE data,

there is some evidence to support a

concern for potential human hazard.

MTBE has been found in some drinking

water wells but it is uncertain whether

the concentrations are at levels of health

concern. Given the potential health

hazard and need for additional data,

MTBE meets the criteria for placement

on the CCL.

The inclusion of a contaminant on the

CCL does not mean that the

contaminant will be regulated. As noted

earlier, contaminants on the CCL

include those for which the Agency

must make a determination of whether

or not to regulate by 2001 pursuant to

the requirements of the SDWA, but it

also includes the Agency’s research
10282 Federal Register / Vol. 63, No. 40 / Monday, March 2, 1998 / Notices

priorities, contaminants for which

monitoring is necessary to gather

additional data. MTBE will remain on

the CCL since the Agency needs

additional occurrence data.

At this time, the EPA has not

included MTBE among the

contaminants for which determinations

will be made by 2001. As stated earlier,

MTBE needs additional health and

occurrence data, and as such, it will be

one of the priority contaminants for

which the Agency will gather such data.

There are no data on the effects on

humans of drinking MTBE

contaminated water. Therefore, EPA is

continuing to evaluate the available

health information and is doing

additional research to seek more

definitive estimates of potential risks to

humans from drinking water. One of the

mechanisms for gathering occurrence

data is to include a contaminant in the

forthcoming Unregulated Contaminant

Monitoring rulemaking to be issued in

August 1999. The Agency is also not

precluded from using other means of

gathering occurrence data which may

include conducting special studies. The

data collection and evaluation efforts

will assist in determining what the

appropriate action should be with

respect to MTBE. Placing MTBE in this

category does not prevent the Agency

from selecting it to make a

determination of whether or not to

regulate by 2001; however, at this time,

it is not likely that the necessary data

will be collected and evaluated in time

to make a determination by this date.

To facilitate data collection and

evaluation efforts for MTBE, an Agencywide task force has been formed and has

prepared a draft Oxygenates in Water

Research Strategy. The Strategy

identifies current, or soon to be started,

research in areas that include

environmental occurrence, source

characterization, transport and

transformation, exposure, toxicity, and

treatment. The Strategy will also

identify key areas of research that are

still necessary to build a stronger, more

informed scientific database to support

health risk assessment and risk

management decisions with respect to

fuel oxygenates, including MTBE.

On October 7, 1997, EPA convened a

day-long meeting of over 50 experts—

including representatives from industry,

academia, consultants, and other

government agencies—to review a draft

of the Strategy. The information

produced in this workshop is being

used to help revise the draft of the

Strategy, which will serve as a blueprint

to assist in coordinating efforts by

various organizations, public and

private, in addressing the issues related

to oxygenates in water. The Agency will

also publish the Strategy in the Federal

Register this Spring, to seek additional

public comment on the research

priorities identified.

J. Organotins

Four commenters argued that

organotins, specifically the mono- and

di-organotins, the only types used as

polyvinyl-chloride (PVC) heat

stabilizers, should not be included on

the CCL. The commenters maintained

that, due to evidence of low toxicity and

low migration (thus, low risk to

consumers), mono- and di-organotins,

especially mono- and di-methyltins,

should not be of concern to drinking

water, particularly in light of the

National Sanitation Foundation (NSF)

certification program for plumbing

materials. Other commenters indicated

that it was premature for the Agency to

regulate organotins, but thought it

prudent that the Agency keep informed

of the issue.

EPA Response

EPA disagrees with the commenters

who suggest that organotins should be

deleted from the CCL. It should be

emphasized that retaining organotins on

the CCL does not necessarily mean that

they will be regulated. The Agency

believes that organotins, including

mono- and di-organotins which are used

as heat stabilizers in PVC and

chlorinated polyvinyl-chloride (CPVC)

pipes, are of sufficient concern to

warrant further investigation. The

Agency is aware of the NSF certification

program, and has noted that many

States require the use of NSF-certified

material in the construction of new

buildings. The Agency agrees with the

NDWAC Working Group

recommendation that an assessment of

the toxicological data underlying the

action levels established by the NSF

needs to be made along with assessment

of other available information on

organotins, before these compounds can

be disregarded as of concern. The

Agency requested this information from

the NSF, and learned that due to

confidentiality agreement, NSF cannot

disclose this information, therefore we

have not yet been able to assess the

toxicological data.

There are numerous concerns about

the occurrence and toxicological

significance of various species of

organotins in drinking water. A recent

report indicates that unlike PVC

systems, new CPVC systems have the

potential to contaminate drinking water

with organotin compounds for a longer

period of time after installation (Forsyth

and Jay 1997). There has been a report

concerning tributyltin contamination of

drinking water from PVC pipes, and

tributyltin is of far more toxicological

significance than mono- and diorganotins (Sadiki et al, 1996). There is

also concern about the recent reports of

teratogenic potential of dibutyltin (Ema

et al, 1996). The Canadian Government

is concerned about organotin

contamination of drinking water and

has launched a national survey.

In view of these concerns, the Agency

believes that organotins, including

mono- and diorganotins, should remain

on the CCL until the Agency can

perform its own in-depth evaluation of

the occurrence and toxicological data of

the contaminants of this class.

K. Perchlorate

The majority of comments on

perchlorate indicated support for its

inclusion on the CCL. Commenters

pointed out that the information on the

occurrence of perchlorate in drinking

water supplies was sufficient to raise

concern over the potential impact on

public health. A few commenters

expressed concern that perchlorate

should not be regulated or that there

was not sufficient information at present

to warrant its regulation, and that a

health advisory would be more

appropriate.

EPA Response

The Agency agrees with commenters

that sufficient information exists to raise

concern over the potential health effects

and occurrence of perchlorate in

drinking water supplies. Despite

significant data gaps regarding health

effects, occurrence, and treatment

technologies, perchlorate has been

found in a number of drinking water

supplies at levels of health concern, and

as a result is included on the final CCL.

The Agency understands that the

extent of actual or even potential

perchlorate contamination is unclear for

many parts of the country, and that for

some areas of the country perchlorate

contamination may not be an issue.

However, perchlorate has been detected

in a number of drinking water supplies

to date and warrants further evaluation.

Placement of perchlorate on the CCL

means that the Agency will make it a

priority to conduct further investigation

and evaluation of the health effects and

national occurrence of perchlorate in

drinking water supplies.

Perchlorate has been placed in the

categories of needing additional health

effects, treatment research, and

occurrence information. Several

toxicological and occurrence studies are

planned or are underway, which will

assist the Agency in filling these data
Federal Register / Vol. 63, No. 40 / Monday, March 2, 1998 / Notices 10283

gaps on perchlorate. At this time, the

Agency has not made a determination to

issue a health advisory or to regulate

perchlorate. The additional data

obtained from these health effects and

occurrence studies will provide a sound

scientific basis for future EPA decisions

of whether to regulate perchlorate or

not, to prepare a health advisory or

guidance, or to include perchlorate in

the Unregulated Contaminant

Monitoring rulemaking. Placing

perchlorate in these categories does not

preclude the Agency from selecting it to

make a determination of whether or not

to regulate by 2001, but at this time it

is unlikely that perchlorate will be

included among those for which

determinations will be made by 2001.

L. Rhodamine WT

A few commenters argued that

Rhodamine WT be removed from the

CCL. The commenters stated that

Rhodamine WT has a very specialized

purpose. They also noted that it is

certified by the NSF and that the

certification is reviewed by EPA. They

also stated that data for including

Rhodamine WT were questionable, and

that the contaminant had no specific

health effect.

EPA Response

EPA agrees with the commenters and

has removed Rhodamine WT from the

CCL. Rhodamine WT was placed on the

draft CCL because it was detected in

ground water above the NSF Standard

60 concentration of 0.1μg/L for drinking

water. However, three concentrations

have been established under the NSF

Standard 60; 0.1μg/L for drinking water,

10μg/L for water entering a drinking

water plant (prior to treatment and

distribution), and 100 μg/L for ground

water not associated with drinking

water production. These concentration

values were developed under the

Agency’s former Additives Program

which was subsequently privatized and

turned over to NSF in the 1980’s.

The maximum concentration of

available occurrence data was 28 μg/L

detected in ground water, and, as such,

should be compared to the

recommended value of 100 μg/L for

ground water, not the value for drinking

water. Given this comparison, the

maximum concentration of 28 μg/l is

well below the recommended value for

ground water of 100 μg/L. When the

NSF guidance regarding the use of

Rhodamine WT as a fluorescent tracer

in water flow studies is followed the

Agency does not anticipate any adverse

health effects resulting from the use of

Rhodamine WT.

M. Sodium

Many commenters were opposed to

including sodium on the CCL, primarily

due to their contention that sodium in

drinking water is not a public health

concern because of its extremely low

level in drinking water, and its small

contribution to overall sodium intake.

Commenters also noted that controlling

sodium in public water systems would

be cost-prohibitive and produce

marginal or nonexistent health benefits.

Commenters argued that food, which is

the major source of sodium, is allowed

to average 440 mg/day under a ‘‘saltrestricted’’ medically-supervised diet,

and that controlling sodium content in

food would address salt-restriction more

directly. Commenters also strongly

disagreed with the use of EPA’s DWEL

of 20 mg/l as the public health criteria

for determining whether to include

sodium on the CCL. The commenters

mentioned a more up-to-date, 1996

report published by the American

Medical Association (AMA) showing a

lack of association between sodium and

blood-pressure, except for older

individuals with existing hypertension.

Other commenters argued for the

inclusion of sodium, citing studies

linking it to hypertension and the need

to maximize protection of salt-sensitive

individuals as a sensitive

subpopulation.

EPA Response

The issue of sodium posed a unique

challenge for the Agency priority setting

and contaminant candidate listing

process. Information from commenters

on each side made important points. On

the one hand, high levels of salt intake

can be associated with hypertension in

some individuals. On the other hand,

sodium levels in drinking water are

unlikely to be a significant contribution

to adverse health effects.

This low level of concern is

compounded by the legitimate

criticisms of EPA’s 20 mg/l guidance

level that was used in this process. EPA

believes this guidance level for sodium

needs updating, and is probably low. If

a health benchmark for drinking water

were established using current

information and current drinking water

health assessment procedures, it would

likely be higher. This revision could

establish a new level at which sodium

occurrence would not meet the criteria

for inclusion on the CCL as a drinking

water contaminant of concern. There

was insufficient time to complete a

reassessment of the sodium guidance in

advance of the CCL issuance.

Given the state of the data, EPA faced

a dilemma on whether or not to list

sodium. A decision not to list would be

justified by the fact that much is known

about sodium and it does not appear to

be a drinking water risk comparable to

other priority contaminants. In fact, this

was the logic supporting the decision

not to include sodium on the previous

drinking water priority list in 1991.

However, a decision to list sodium

would afford EPA the opportunity to

address the confusion surrounding the

current guidance for sodium in drinking

water.

In the end, EPA decided to include

sodium on the CCL, primarily as a

vehicle to reexamine and correct the

current, outdated guidance. Therefore,

sodium is listed, not as a Regulatory

Determinations Priority, but as a

Research Priority to allow time to

evaluate and revise the Agency

guidance. When this is completed, EPA

will reevaluate whether sodium merits

retention on the CCL for any further

action.

N. Triazines

Many commenters applauded EPA’s

intention to address triazines and their

metabolites as a group a ‘‘good first

step’’ to addressing these compounds. A

number of commenters indicated that

we should include other triazine

degradation products such as

deisopropyl atrazine and

diaminochlorotriazine (same as diamino

atrazine) because they too are common

degradation products of atrazine as well

as simazine, and are found at higher

concentrations than atrazine-desethyl.

Once commenter expressed concern that

additional information was being

considered and evaluated by the Agency

under the OPP Special Review program,

and that these reviews should be

completed before triazines are

considered for the CCL.

EPA Response

The Agency agrees with the points

raised by the commenters regarding the

triazine degradation products. As a

result, the EPA has decided to include

triazines and their degradation products

(including but not limited to: cyanazine

and atrazine-desethyl) on the CCL as a

group to include all potential risks from

this class of compounds. Stakeholders,

through the regulatory reassessment

process in developing the redirection

strategy, and through the development

of this draft CCL, have requested that

the Agency address triazine pesticides

as a group, which includes all parent

and degradate compounds, as opposed

to each triazine as an individual

contaminant.

The EPA has been studying the

mechanism of carcinogenicity of this
10284 Federal Register / Vol. 63, No. 40 / Monday, March 2, 1998 / Notices

group of analogues along with their

degradation products, and will continue

to study these chemicals as a group to

characterize their risk in drinking water.

The Agency regulated atrazine in 1991

and simazine in 1992. The Agency may

ultimately develop regulations for the

mixtures of triazines either through the

revision of existing regulations or the

development of new ones.

EPA disagrees with the notion that

triazines should be excluded from the

CCL until after the completion of the

Special Reviews. The triazines are

included in the Priority Group 1 of

pesticide tolerances that will be

examined first under the Food Quality

Protection Act (FQPA) tolerance

reassessment (62 FR 42020). The work

being accomplished by OPP in their

review efforts will certainly be factored

into EPA’s decisions regarding triazines,

as with all pesticides on the CCL.

O. Zinc

Two commenters were opposed to the

inclusion of zinc on the CCL. The

commenters argued that zinc did not

meet the criteria for inclusion on the

CCL, and is generally non-toxic to

animals and humans. They pointed out

that zinc is used in a wide variety of

products, and is also an essential

element. One commenter stated that the

Agency had not considered zinc’s

beneficial qualities when deciding

whether it should be included on the

CCL, and that the WHO and EPA have

both stated that deficiency of zinc is

more of a concern than over-exposure.

The commenter further argued that the

history of the substitution from the 1988

DWPL was not considered, and that the

HA value used in the Agency’s analysis

was from a ‘‘7-yr old draft’’ which was

not available for comment and therefore

the explanation behind the Agency’s

HAL of 2,000 μg/l was not available for

comment.

EPA Response

The EPA agrees with the commenter

on the point raised that zinc does not

meet the criteria for inclusion on the

CCL, and has removed zinc from the

CCL. The Agency has determined that

the number of public water systems

with zinc levels above 1,000 μg/l is 4,

and none had occurrence levels above

2,000 μg/l, and, as a result, zinc doesn’t

meet the criteria for inclusion on the

CCL. The criterion for a contaminant to

be included on the CCL was

‘‘occurrence at the health level of

concern in 10 or more small public

water systems.’’ The action of removing

zinc from the CCL was due to its lack

of occurrence in water systems at health

levels of concern, not due to its lack of

toxicity. It is known that daily exposure

to zinc of approximately 60 mg/l (60,000

μg/l) or more can effect copper

metabolism, and result in deleterious

health effects.

IV. Continuing Work in Preparation for

Future CCLs

In the Federal Register notice on the

draft CCL, the Agency deferred action

on a number of pesticides, and

contaminants implicated as endocrine

disruptors, in anticipation of impending

resolution specific to these two groups

of contaminants. Action on these

contaminants continues to be deferred

and these contaminants will be

reconsidered when the next CCL is

developed. The Agency is also resuming

work on a contaminant identification

process to be used in the development

of future CCLs. Further discussion of

these three topics follows.

A. Pesticides Deferred

In developing the CCL, the SDWA

requires EPA to consider substances

registered as pesticides under FIFRA.

During the development of the CCL, the

Agency’s Office of Ground Water and

Drinking Water sought assistance from

OPP in determining what pesticides

should be priorities for the drinking

water program. In response to the

request, OPP provided

recommendations for a number of

pesticides based on physical-chemical

properties, occurrence and extent of use,

using the Ground Water (GW) Risk

score. The GW-Risk score is a calculated

potential of pesticides to leach to

ground water. Pesticides with a GWRisk of 2.0 or greater were included for

initial consideration in developing the

draft CCL.

However, later during the data

evaluation and screening phase of the

CCL development, the decision was

made to defer pesticides identified by

the GW-Risk of 2.0 or greater for which

no additional information was available.

Inclusion on the CCL would be deferred

pending further evaluation of the

potential of these pesticides to occur at

levels of health concern. The Agency is

working to develop a tool to estimate

concentrations in ground and surface

waters based on physical-chemical

properties and pesticide use volumes,

and will then compare the estimated

concentrations with health advisory

levels or calculated health levels based

on reference doses or cancer potency.

It was anticipated that the tool to

estimate concentrations of pesticides in

ground and surface waters would be

completed and available in time to

reevaluate the inclusion of the

additional pesticides prior to

completing the CCL. However, the

Agency believes it is important to have

this tool peer-reviewed prior to its use,

which would increase the time

necessary for its development beyond

the time available. Therefore, EPA did

not attempt to complete this work before

finalizing the CCL in today’s notice. As

a result, action on these pesticides

remains deferred until the next CCL.

On December 10, 1997, the Science

Advisory Panel (SAP) met to discuss

drinking water exposure assessment

issues with the OPP. The objective of

the meeting was to obtain SAP’s

recommendation on the approaches and

models developed by OPP to determine

short-term and long-term potential

exposures from pesticides in drinking

water. The issues of monitoring

requirements, and assessing impacts of

exposure to mixtures were also part of

the discussion. The approaches and

models developed by OPP and the

forthcoming SAP’s recommendations on

these issues are of particular importance

to the Office of Water in that the

outcome will be used in the drinking

water program as well.

B. Endocrine Disruptors

During the development of the draft

CCL, the Agency initially considered,

then later deferred, a number of

contaminants implicated or suspected

as substances which disrupt the

function of the endocrine system. As

stated in the notice of the draft CCL,

EPA issued an interim assessment in

February 1997, pending a more

extensive review expected to be issued

by the National Academy of Sciences

(NAS), determining that, while effects

have been found in laboratory animal

studies, a causal relationship between

exposure to a specific environmental

agent and an adverse health effect in

humans operating via endocrine

disruption has not been established,

with a few exceptions. Further research

is needed before such effects can be

demonstrated.

Under the SDWA, as amended, the

Agency is also required to establish a

program to screen endocrine disrupting

contaminants. Additional authority to

assess endocrine disruptors is also

provided through the recently enacted

FQPA. EPA’s Office of Prevention,

Pesticides, and Toxic Substances

(OPPTS) has the Agency lead on

endocrine disruptor screening and

testing issues, and is actively engaged in

research and regulatory initiatives to

respond to the growing scientific and

public concern over endocrine

disruptors. Also, the Endocrine

Disruptor Screening and Testing

Advisory Committee (EDSTAC) has
Federal Register / Vol. 63, No. 40 / Monday, March 2, 1998 / Notices 10285

been established to provide advice and

counsel to the Agency in implementing

a screening and testing strategy required

under the FQPA and SDWA. EDSTAC

will complete its recommendations for a

screening and testing strategy by March

1998. The recommendations will be

peer-reviewed jointly by the SAB and

the FIFRA SAP.

As a result, pending completion of the

EDSTAC’s recommendations and the

additional review of endocrine

disruptors by the NAS, EPA has not

included contaminants for inclusion on

this first CCL based solely on the

possibility of endocrine disruption

(although several contaminants

implicated as endocrine disruptors were

considered for other reasons). As stated

in the notice on the draft CCL, the

Agency will continue to follow this

issue closely and reconsider this

category of potential contaminants in

the development of future CCLs.

C. Development of the Contaminant

Selection Process

This CCL is largely based on

knowledge acquired over the last few

years and other readily available

information, but an enhanced, more

robust approach to data collection and

evaluation will be developed for future

CCLs. The Agency will also resume

work on the contaminant identification

and the contaminant selection process.

The CCL, and the identification and

selection process will serve as the

cornerstones of the Agency’s regulatory

development process. In addition to

developing the CCL, and the

identification and selection process, the

Agency intends to obtain resources in

order to acquire better data and

information, improve analytical

capability, and seek additional

stakeholder involvement.

The next steps for improving the

contaminant identification and selection

process include an American Water

Works Association Research Foundation

(AWWARF) project utilizing a series of

workshops in which established

decision-making tools would be

employed to develop a process to

identify emerging pathogens of concern

for consideration, regulation, and future

research. The work is expected to begin

in June/July 1998. A project with the

NAS will also be undertaken to solicit

input on criteria for listing and selecting

chemical contaminants for future CCLs.

A panel is currently being formed and

work is expected to begin in summer of

1998. The development of the

identification and the selection process

will be completed in consultation with

the NDWAC and the Working Group on

Occurrence & Contaminant Selection,

and their future involvement is likely to

include reviewing products from

AWWARF and NAS in 1999. The CCL

is a critical input to shaping the future

direction of the drinking water program,

and improvements to the process will be

made with each successive cycle of

publishing the list.

V. Data, Research Needs and Next Steps

Table 2 divides the CCL into

categories to represent the next steps

and data needs for each contaminant.

Sufficient data are needed to conduct

analyses on extent of exposure and risk

to populations via drinking water in

order to determine appropriate Agency

action (development of health

advisories, or regulations, or no action)

for many of these contaminants. If

sufficient data are not available, they

must be obtained before such an

assessment can be made. The data and

information required will be gathered by

research or monitoring programs, and

are not likely to be available for analyses

to be completed prior to 2001. Thus, the

contaminants for which sufficient data

exist at the time of publishing the CCL

are likely to be those from which the

determinations will be made by 2001.

However, it should be noted that the

groupings in Table 2 are based on

current information, and some

movement of contaminants between

categories can be expected as more

information is evaluated and analyzed.

The Regulatory Determination Priorities

category in Table 2 will be used to select

5 or more contaminants for which the

Agency must determine, by August

2001, whether or not regulations should

be developed. To make these

determinations, further analysis of data

currently available, or data that will

become available within a short period,

is required to prepare supporting

documents addressing health criteria,

cost and benefit assessments, and

analyses of analytical methods,

occurrence, and treatment technology

and feasibility. For contaminants in the

category, there may also be some shortterm research needs, such as benchscale treatability studies, that must also

be completed. The next steps for the

Agency regarding the contaminants in

this category are to determine which

contaminants to address first, and

outline plans of action to work towards

making determinations for five or more

by August 2001.

The contaminants in the Research

Priorities category have significant data

gaps in areas of health, treatment, or

analytical methods. For these

contaminants, the research, or data

gathering, and subsequent analysis

needed are not expected to be complete

within the 31⁄2 years, by August 2001, in

order to make determinations of

whether regulation of these

contaminants is necessary. These are

EPA’s priority contaminants for research

and data gathering. Some of these

research needs are currently being

addressed by EPA or other agencies

(e.g., Department of Defense for

perchlorate), while other needs are

newly identified.

The contaminants in the Occurrence

Priorities category have significant data

gaps in occurrence data. The

Unregulated Contaminant Monitoring

Regulations (UCMR) will be the primary

source for data for most contaminants

included in this category; however,

some contaminants may be more

appropriate for special studies or

surveys, or joint data gathering efforts

with other Agencies. Also, for some

contaminants, suitable analytical

methods must be developed prior to

obtaining the occurrence data necessary.

The next steps for the Agency are to

develop short- and long-term research

plans on health, treatment, and

methods, to develop the UCMR proposal

(expected August 1998) for gathering

occurrence data, and to plan for special

occurrence studies, where appropriate.

The Agency will also use its FIFRA and

Toxic Substances Control Act (TSCA)

authorities, as appropriate, to conduct

studies and obtain data necessary for

decision-making.
10286 Federal Register / Vol. 63, No. 40 / Monday, March 2, 1998 / Notices

TABLE 2.—NEXT STEPS FOR THE CCL

Regulatory determination

priorities

Research priorities

Occurrence priorities

Health research Treatment research Analytical methods

research

Acanthamoeba (guidance)

1,1,2,2-tetrachloroethane

1,1-dichloroethane

1,2,4-trimethylbenzene

1,3-dichloropropene

2,2-dichloropropane

Aldrin

Boron

Bromobenzene

Dieldrin

Hexachlorobutadiene

p-Isopropyltoluene

Manganese

Metolachlor

Metribuzin

Naphthalene

Organotins

Triazines & degradation

products (incl., but not

limited to Cyanazine and

atrazine-desethyl)

Sulfate

Vanadium

Aeromonas hydrophila

Cyanobacteria (Blue-green

algae), other freshwater

algae, and their toxins

Caliciviruses

Helicobacter pylori

Microsporidia

Mycobacterium avium

intercellulare (MAC)

1,1-dichloropropene

1,3-dichloropropane

Aluminum

DCPA mono-acid & di-acid

degradates

Methyl bromide

MTBE

Perchlorate

Sodium (guidance)

Adenoviruses

Aeromonas hydrophila

Cyanobacteria (Blue-green

algae), other freshwater

algae, and their toxins

Caliciviruses

Coxsackieviruses (ICR

data)

Echoviruses (ICR data)

Helicobacter pylori

Microsporidia

Mycobacterium avium

intracellulare (MAC)

Aluminum

MTBE

Perchlorate

Adenoviruses

Cyanobacteria (Blue-green

algae), other freshwater

algae, and their toxins

Caliciviruses

Helicobacter pylori

Microsporidia

1,2-diphenylhydrazine

2,4,6-trichlorophenol

2,4-dichlorophenol

2,4-dinitrophenol

2-methyl-Phenol

Acetochlor

Alachlor ESA

Fonofos

Perchlorate

RDX

Adenoviruses.*

Aeromonas hydrophila.

Cyanobacteria (Blue-green

algae), other freshwater

algae, and their toxins.*

Caliciviruses.*

Coxsackieviruses (ICR

data).

Echoviruses (ICR data).

Helicobacter pylori.*

Microsporidia.*

1,2-diphenylhydrazine.*

2,4,6-trichlorophenol.*

2,4-dichlorophenol.*

2,4-dinitrophenol.*

2,4-dinitrotoluene.

2,6-dinitrotoluene.

2-methyl-phenol.*

Alachlor ESA* and

Acetochlor.*

DCPA mono-acid & di-acid

degradates.

DDE.

Diazinon.

Disulfoton.

Diuron.

EPTC.

Fonofos.*

Linuron.

Molinate.

MTBE.

Nitrobenzene.

Perchlorate.*

Prometon.

RDX.*

Terbacil.

Terbufos.

The groupings in Table 2 are based on current information, and some movement of contaminants between categories can be expected as

more information is evaluated and analyzed. *Suitable analytical methods must be developed prior to obtaining occurrence data.

VI. Other Requirements

The CCL is a notice and not a

regulatory action; therefore, the

following statutes and executive orders

are not applicable at this time: the

Regulatory Flexibility Act, Small

Business Regulatory Enforcement

Fairness Act, Paperwork Reduction Act,

Unfunded Mandates Reform Act; and

Executive Order 12866. For any

contaminants selected for rule-making,

all necessary analysis will be conducted

in accordance with the rule-making

process.

Executive Order 13045, Protection of

Children from Environmental Health

Risks and Safety Risks, requires that

Federal Agencies identify and assess

health risks and safety risks that

disproportionately affect children, and

ensure that its policies, programs,

activities, and standards address

disproportionate health and safety risks

to children. The SDWA also requires the

Agency to select priorities for regulation

while considering risks to sensitive

subpopulations, such as infants and

children.

The impact on sensitive populations

will be addressed in the contaminant

selection process, and will be a

component of the Agency’s

determination of whether or not to

regulate a given contaminant. In

preparation for addressing the issues of

sensitive subpopulations, the Agency is

sponsoring several activities to

determine water intake by age group, by

demographic distribution, and by innate

or developed sensitivity to potential

drinking water contaminants. The

Agency is also collaborating with the

Center for Disease Control and

Prevention on a study of six major cities

to determine the most sensitive

populations for drinking water

manifested during major outbreaks of

illness from incidents of water. Other

research also is underway to determine

the extent of vulnerable populations

including children and the

immunologically impaired.

VII. References

Benenson, A.S. 1995. Control of

Communicable Diseases Manual (16th

ed.). pp. 10–13. American Public Health

Assoc., Washington.

Ema, M., R. Kurosaka, H. Amano, and Y.

Ogawa. 1996. Comparative

Developmental Toxicity of Di-, Tri-and

Tetrabutyltin Compounds after

Administration during Late

Organogenesis in Rats. J. Appl. Toxicol.,

16(1), 71–76.

Forsyth, D.S., and B. Jay. 1997. Organotin

Leachate in Drinking Water from

Chlorinated Polyvinyl Chloride (CPVC)

Pipe. Appl. Organometallic Chem.,

11:551–558.

Johnson, C.H., E.W. Rice and D.J. Reasoner.

1997. Inactivation of Helicobacter pylori

by chlorination. Appl. Environ.

Microbiol. 63:4969–4970.
Federal Register / Vol. 63, No. 40 / Monday, March 2, 1998 / Notices 10287

Mast, E.E., and K. Krawczynski. 1996.

Hepatitis E: An Overview. Annual Rev.

Med. 47:257–266.

Midgley, J.P., A.G. Matthew, C.M.T.

Greenwood, and A.G. Logan. 1996. Effect

of Reduced Dietary Sodium on Blood

Pressure. J. Amer. Med. Assoc., 275 (20):

1590–1597.

RDA. 1989. Recommended Dietary

Allowances, tenth edition. National

Research Council, National Academy

Press, Washington, D.C., 284 pp.

Sadiki, Abdel-Iiah, D. Williams, R. Carrier

and B. Thomas. 1996. Pilot study of the

Contamination of Drinking Water by

Organotin Compounds from PCV

Materials. Chemosphere, 32:2389–2398.

U.S. EPA. 1995. ‘‘Acetone; Toxic Chemical

Release Reporting; Community Right-toKnow, Final Rule,’’ 60 FR No. 116,

31643–31646, June 16.

U.S. EPA. 1996. ‘‘Drinking Water Program

Redirection Strategy,’’ Office of Water.

EPA 810–R–96–003, June.

U.S. EPA. 1997. ‘‘Announcement of the Draft

Drinking Water Contaminant Candidate

List; Notice,’’ 62 FR No. 193 52194–

52219, October 6.

U.S. EPA. 1998. ‘‘Response to Comment

Document.’’ Office of Ground Water and

Drinking Water.

(Authority: 42 U.S.C. 300f–300j–25)

Dated: February 6, 1998.

Robert Perciasepe,

Assistant Administrator, Office Water,

Environmental Protection Agency.

[FR Doc. 98–5313 Filed 2–27–98; 8:45 am]

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