1
ENVIRONMENTAL
PROTECTION
AGENCY
40
CFR
Part
141
[
OW­
2003­
0028;
FRL­_______­_______]

[
RIN
2060­
AD86]

Drinking
Water
Contaminant
Candidate
List
2;
Final
Notice
AGENCY:
Environmental
Protection
Agency.

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
that,
at
the
time
of
publication,
are
not
subject
to
any
proposed
or
promulgated
national
primary
drinking
water
regulations,
that
are
known
or
anticipated
to
occur
in
public
water
systems,
and
that
may
require
regulations
under
SDWA
(
section
1412
(
b)(
1)).
SDWA,
as
amended,
specifies
that
EPA
must
publish
the
first
list
of
drinking
water
contaminants
no
later
than
18
months
after
the
date
of
enactment,
i.
e.,
by
February
1998,
and
every
five
years
thereafter.

The
EPA
published
the
first
Candidate
Contaminant
List
(
CCL)
in
March
of
1998
(
63
FR
2
10273).
The
second
draft
CCL
(
CCL
2)
was
published
on
April
2,
2004
(
69
FR
17406)
and
announced
EPA's
preliminary
decision
to
carry
forward
the
remaining
51
contaminants
on
the
1998
CCL
as
the
draft
CCL
2,
provided
information
on
EPA's
efforts
to
expand
and
strengthen
the
underlying
CCL
listing
process
to
be
used
for
future
CCL
listings,
and
sought
comment
on
the
draft
list
as
well
as
EPA's
efforts
to
improve
the
contaminant
selection
process
for
future
CCLs.

Today's
final
CCL
2
carries
forward
the
remaining
51
contaminants
proposed
on
April
2,
2004.

ADDRESSES:
EPA
has
established
a
docket
for
this
action
under
Docket
ID
No.
OW­
2003­

0028.
All
documents
in
the
docket
are
listed
in
the
EDOCKET
index
at
http://
www.
epa.
gov/
edocket.
Although
listed
in
the
index,
some
information
is
not
publically
available,
i.
e.,
CBI
or
other
information
whose
disclosure
is
restricted
by
statute.
Certain
other
material,
such
as
copyrighted
material,
is
not
placed
on
the
Internet
and
will
be
publically
available
only
in
hard
copy
form.
Publically
available
docket
materials
are
available
either
electronically
in
EDOCKET
or
in
hard
copy
at
the
Water
Docket,
EPA/
DC,
EPA
West,
Room
B102,
1301
Constitution
Avenue,
NW,
Washington,
DC.
The
Public
Reading
Room
is
open
from
8:
30
a.
m.

to
4:
30
p.
m.,
Monday
through
Friday,
excluding
legal
holidays.
The
telephone
number
for
the
Public
Reading
Room
is
(
202)
566­
1744,
and
the
telephone
number
for
the
Water
Docket
is
(
202)

566­
2426.
For
access
to
docket
material,
please
call
(
202)
566­
2426
to
schedule
an
appointment.

FOR
FURTHER
INFORMATION
CONTACT:
For
questions
about
this
notice
contact
Dan
Olson,
Standards
and
Risk
Management
Division,
Office
of
Ground
Water
and
Drinking
Water
(
MC­
4607M),
Environmental
Protection
Agency,
1200
Pennsylvania
Ave.,
NW.,
Washington,

DC
20460;
telephone
number:
202­
564­
5239;
fax
number:
202­
564­
3752;
e­
mail
address:

olson.
daniel@
epa.
gov.
For
general
information
contact
the
EPA
Safe
Drinking
Water
Hotline
at
3
(
800)
426­
4791
or
e­
mail:
hotline­
sdwa@
epa.
gov.
The
Safe
Drinking
Water
Hotline
is
open
Monday
through
Friday,
excluding
legal
holidays,
from
9:
00
a.
m.
to
5:
00
p.
m.

SUPPLEMENTARY
INFORMATION
I.
General
Information
A.
Does
this
Action
Impose
Any
Requirements
on
My
Public
Water
System?

Today's
action
does
not
impose
any
requirements
on
anyone.
Instead,
it
notifies
interested
parties
of
EPA's
final
CCL
2
as
well
as
EPA's
efforts
to
improve
the
contaminant
selection
process
for
future
CCLs.
Contaminants
on
the
list
will
be
considered
under
the
regulatory
determination
provision
of
SDWA
(
see
section
1412(
b)(
1)(
B)(
ii)),
which
directs
EPA
to
select
at
least
five
contaminants
from
the
CCL
every
five
years
to
determine
if
regulating
the
contaminants
through
National
Primary
Drinking
Water
Regulations
would
present
a
meaningful
opportunity
to
reduce
health
risk.

II.
Background
and
Summary
of
Today's
Action
A.
What
is
the
Purpose
of
Today's
Action?

The
CCL
is
the
primary
source
of
priority
contaminants
for
evaluation
by
EPA's
drinking
4
water
program.
Contaminants
on
the
CCL
are
currently
not
subject
to
any
proposed
or
promulgated
national
primary
drinking
water
regulation,
but
are
known
or
anticipated
to
occur
in
public
water
systems,
and
may
require
regulation
under
SDWA.
The
EPA
conducts
research
on
health
effects,
analytical
methods,
contaminant
occurrence,
treatment
technologies,
and
treatment
effectiveness
for
priority
drinking
water
contaminants
on
the
CCL.
The
Agency
also
develops
drinking
water
guidance
and
health
advisories,
and
makes
regulatory
determinations
for
priority
contaminants
on
the
CCL.

Today's
action
informs
interested
parties
of
EPA's
final
CCL
2
as
well
as
EPA's
efforts
to
improve
the
contaminant
selection
process
for
future
CCLs.

B.
The
Background
of
the
CCL.

The
SDWA
is
the
core
statute
protecting
drinking
water
at
the
Federal
level.
Under
SDWA,
EPA
sets
public
health
goals
and
enforceable
standards
for
drinking
water
quality.
In
1996,
Congress
amended
SDWA
to
emphasize
sound
science
and
risk­
based
priority­
setting.

Congress
also
changed
the
way
drinking
water
regulatory
priorities
are
set
by
establishing
the
CCL
requirements.
The
1996
SDWA
amendments
require
EPA
to
(
1)
publish
every
five
years
a
list
of
currently
unregulated
contaminants
in
drinking
water
that
may
pose
risks
(
the
CCL),
and
(
2)
make
determinations
on
whether
or
not
to
regulate
at
least
five
of
these
contaminants
on
a
five
year
cycle,
or
three
and
a
half
years
after
each
CCL
is
published
(
SDWA
section
(
b)(
1)).

Today's
action
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
5
water
regulation,
are
known
or
anticipated
to
occur
in
public
water
systems,
and
may
require
regulation
under
the
SDWA.
A
draft
CCL
2
was
published
in
the
April
2,
2004
edition
of
the
Federal
Register
(
69
FR
17406)
to
announce
EPA's
preliminary
decision
to
carry
forward
the
remaining
51
contaminants
on
the
1998
CCL
as
the
CCL
2,
to
provide
information
on
EPA's
efforts
to
expand
and
strengthen
the
underlying
CCL
listing
process
to
be
used
for
future
CCL
listings,
and
to
seek
comment
on
the
draft
list
as
well
as
EPA's
efforts
to
improve
the
contaminant
selection
process
for
future
CCLs.

Today's
action
establishes
the
final
CCL
2
which
includes
42
chemicals
or
chemical
groups
and
nine
microbiological
contaminants.
This
list
continues
to
be
an
important
tool
under
the
SDWA
to
help
prioritize
research
and
serves
as
the
central
focus
of
the
regulatory
determination
process
noted
previously.
It
is
important
to
note,
however,
that
under
the
SDWA,

the
EPA
may
also
make
regulatory
determinations
for
any
unregulated
contaminant
not
on
today's
CCL
(
see
SDWA
section
1412(
b)(
1)(
B)(
ii)(
III)).
Thus,
the
Agency
has
the
authority
to
act
as
necessary
to
protect
public
health
as
new
information
becomes
available.

III.
Drinking
Water
Contaminant
Candidate
List
2
Table
III­
1
lists
the
contaminants
on
the
final
CCL
2.
These
contaminants
are
identified
by
name
and,
where
available,
the
Chemical
Abstracts
Service
Registry
Number
(
CASRN).
The
final
CCL
2
consists
of
nine
microbiological
contaminants
and
42
chemical
contaminants
or
contaminant
groups.
6
Table
III­
1.
Final
Drinking
Water
Contaminant
Candidate
List
2.

Microbiological
Contaminant
Candidates
Adenoviruses
Aeromonas
hydrophila
Caliciviruses
Coxsackieviruses
Cyanobacteria
(
blue­
green
algae),
other
freshwater
algae,
and
their
toxins
Echoviruses
Helicobacter
pylori
Microsporidia
(
Enterocytozoon
and
Septata)

Mycobacterium
avium
intracellulare
(
MAC)

Chemical
Contaminant
Candidates
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
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
Chemical
Contaminant
Candidates
CASRN
7
Alachlor
ESA
&
other
acetanilide
pesticide
degradation
products
N/
A
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
Disulfoton
298­
04­
4
Diuron
330­
54­
1
EPTC
(
s­
ethyl­
dipropylthiocarbamate)
759­
94­
4
Fonofos
944­
22­
9
p­
Isopropyltoluene
(
p­
cymene)
99­
87­
6
Linuron
330­
55­
2
Methyl
bromide
74­
83­
9
Methyl­
t­
butyl
ether
(
MTBE)
1634­
04­
4
Metolachlor
51218­
45­
2
Molinate
2212­
67­
1
Nitrobenzene
98­
95­
3
Organotins
N/
A
Perchlorate
14797­
73­
0
Prometon
1610­
18­
0
RDX
121­
82­
4
Terbacil
5902­
51­
2
Terbufos
13071­
79­
9
Chemical
Contaminant
Candidates
CASRN
8
Triazines
and
degradation
products
of
triazines
including,
but
not
limited
to
Cyanazine
21725­
46­
2
and
atrazine­
desethyl
6190­
65­
4
Vanadium
7440­
62­
2
IV.
Summary
of
Comments
The
comment
period
on
the
April
2,
2004,
Federal
Register
notice,
"
Drinking
Water
Contaminant
Candidate
List
2;
Notice"
(
69
FR
17406)
ended
on
June
1,
2004.
EPA
received
a
total
of
seven
comments
that
focused
on
EPA's
draft
CCL
2
and
EPA's
efforts
to
improve
the
contaminant
selection
process
for
future
CCLs.
EPA
received
two
comments
from
associations
representing
water
utilities,
one
comment
from
a
State­
related
association,
one
comment
from
a
water
utility,
one
comment
from
a
State
agency,
one
comment
from
an
individual,
and
one
anonymous
comment.
A
summary
of
these
comments
and
EPA's
response
to
these
comments
follow.
A
complete
copy
of
the
public
comments
and
the
Agency's
responses
are
included
in
the
Docket
for
today's
action
and
can
be
obtained
at
http://
www.
epa.
gov/
edocket/.

The
majority
of
comments
were
supportive
of
the
CCL
process.
The
comments
on
development
of
the
draft
CCL
2
focused
on
two
key
topic
areas:
(
1)
reassembling
the
CCL
taking
new
available
information
into
account;
suggestions
on
information
that
should
be
considered,
and
contaminants
that
should
be
included
or
deleted
from
the
CCL;
and
(
2)
requests
for
information
on
the
status
of
CCL­
related
research.
Comments
on
the
development
of
future
CCLs
focused
on
four
key
topic
areas:
(
1)
expert
judgement
and
transparency,
(
2)
the
role
of
data
quality,
(
3)
a
simplified
approach
with
adaptive
management
for
future
CCLs,
and
(
4)
the
role
of
virulence
9
factor
activity
relationships
(
VFARs).
The
remainder
of
this
section
discusses
these
key
areas
in
turn.

A.
Developing
the
draft
CCL
2.

1.
Suggestions
on
new
information
and
contaminants
that
should
be
included
or
deleted
from
the
CCL.

Comment
Summary:
Two
commenters
believe
that
EPA
should
create
a
new
CCL
taking
new
available
information
into
account.
One
commenter
recommended
that
EPA
not
carry
forward
five
chemicals
(
1,1,2,2­
tetrachloroethane,
1,1­
dichloropropene,
1,3­
dichloropropane,
1,3­

dichloropropene,
and
2,2,
dichloropropane)
currently
on
CCL
1
to
CCL
2,
two
commenters
recommended
that
N­
nitrosodimethylamine
(
NDMA)
should
be
added
to
the
CCL,
and
one
commenter
recommended
that
enterotoxigenic
Escherichia
coli
(
E.
coli)
be
included
on
the
final
CCL
2.

Agency
Response:
In
response
to
commenters
who
recommended
that
EPA
create
a
new
CCL
to
take
new
available
information
into
account,
and
the
suggestion
that
EPA
remove
five
chemicals
(
1,1,2,2­
tetrachloroethane,
1,1­
dichloropropene,
1,3­
dichloropropane,
1,3­

dichloropropene,
and
2,2,
dichloropropane)
from
the
CCL,
EPA
does
not
believe
that
it
is
appropriate
to
create
a
new
CCL,
or
remove
any
contaminants
from
the
CCL,
at
this
time.
Where
there
is
adequate
information
about
a
particular
contaminant,
EPA
plans
to
make
a
regulatory
determination
which
will
either
remove
that
contaminant
from
the
CCL
or
start
a
national
rule
10
making
process
to
set
a
national
primary
drinking
water
regulation.
With
regard
to
future
CCLs,

EPA
is
developing
an
expanded
comprehensive
system
for
evaluating
a
wider
range
of
existing
information,
identifying
new
data,
and
applying
revised
screening
criteria
to
generate
the
CCL
3
in
response
to
extensive
recommendations
from
the
National
Academy
of
Sciences
National
Research
Council
(
NRC)
and
National
Drinking
Water
Advisory
Council
(
NDWAC).

With
specific
regard
to
NDMA,
there
is
already
a
substantive
body
of
health
effects
research
that
the
Agency
has
relied
upon
to
classify
it
as
a
"
probable
human
carcinogen"
(
USEPA,

1993).
The
key
information
gap
for
this
contaminant
relates
to
occurrence
in
public
water
system
distribution
systems.
Some
initial
research
has
been
conducted
in
this
area
and
the
Agency
plans
to
collect
more
comprehensive
occurrence
information
as
part
of
the
upcoming
national
survey
of
key
unregulated
contaminants
under
section
1445(
a)(
2).

Regarding
enterotoxigenic
E.
coli,
EPA
will
be
considering
this
microbe
as
part
of
the
revised
and
expanded
CCL
3
review
process.
The
Agency
believes
that
this
will
be
a
more
appropriate
and
effective
approach
for
evaluating
this
bacteria
in
comparison
to
a
wide
range
of
other
microbes
that
will
be
considered
under
the
broader
analytical
approach
recommended
by
the
NRC
and
NDWAC.

2.
Provide
the
status
of
CCL­
related
research,
data
collection,
and
pending
initiatives
that
have
been
undertaken
since
CCL
1.

Comment
Summary:
Commenters
identified
several
CCL­
related
research
activities
that
have
been
undertaken
since
CCL
1
and
requested
that
EPA
provide
the
status
of
CCL­
related
11
research,
data
collection,
and
pending
initiatives
that
have
been
undertaken
since
CCL
1.

Two
commenters
also
requested
information
about
the
Agency's
progress
to
date
and
the
intended
future
path
for
integrating
the
35
deferred
pesticides
and
21
contaminants
(
suspected
of
having
adverse
effects
on
endocrine
function)
into
the
CCL
process.

Agency
Response:
EPA
agrees
that
the
status
of
CCL­
related
research
should
be
publically
available.
The
Agency
has
taken
a
number
of
steps
to
provide
this
information
through
its
websites
and
in
documents
it
has
published.

EPA
websites
addressing
CCL­
related
research
information
include
the
following:

°
EPA's
Office
of
Ground
Water
and
Drinking
Water
Drinking
Water
Research
Information
Network
(
DRINK),
found
at
http://
www.
epa.
gov/
safewater/
drink/
intro.
html,
is
a
publicly
accessible,
web
based
system
that
tracks
over
1,000
ongoing
research
projects
conducted
by
EPA
and
other
research
partners
from
national,
regional,
and
international
research
agencies
and
organizations.
The
DRINK
system
stores,
manages,
and
delivers
descriptive
summary
data
on
drinking
water­
related
projects,
including
abstracts,
status
of
projects,

uniform
resource
locators
to
datasets
and
reports,
and
contact
information
on
projects.

°
EPA's
Office
of
Ground
Water
and
Drinking
Water
website
at
http://
www.
epa.
gov/
safewater/
ccl/
cclfs.
html
has
information
on
the
NDWAC
(
e.
g.,

reports,
meeting
announcements,
and
meeting
summaries
which
includes
meetings
of
the
NDWAC
CCL
Work
Group),
monitoring
of
unregulated
contaminants
from
public
water
systems,
the
National
Contaminant
Occurrence
Database,
analytical
methods
for
compliance
monitoring,
and
treatment
technologies.

°
EPA's
Office
of
Research
and
Development
(
ORD)
environmental
information
12
management
system
website
at
http://
www.
epa.
gov/
eims/
maintains
information
on
EPA
research
projects,
including
project
title,
abstract,
start
and
end
dates,
principal
investigator,
funding,
results
and
publications,
and
related
technical
documents.

°
EPA's
Office
of
Science
and
Technologies
website
at
http://
www.
epa.
gov/
waterscience/
humanhealth/
has
information
on
EPA's
drinking
water
standards,
health
and
consumer
advisories,
criteria
documents,
and
related
technical
documents.

A
key
document
addressing
CCL­
related
research
and
information
is
EPA's
Draft
Multi­

Year
Plan
(
MYP)
for
the
drinking
water
research
program.
The
Draft
MYP
describes
the
Agency's
drinking
water
research
program
activities
and
plans
for
fiscal
years
2003
­
2010
(
see
http://
www.
epa.
gov/
osp/
myp/
dw.
pdf).
As
a
tool
for
planning
and
communication,
the
MYP
provides:
(
1)
a
context
for
annual
planning
decisions
and
a
basis
for
describing
the
impacts
of
these
decisions;
(
2)
a
framework
for
integrating
research
on
common
issues
across
the
EPA's
ORD
laboratories
and
centers,
as
well
as
across
the
various
Agency
Goals
established
under
the
Government
Performance
and
Results
Act;
and
(
3)
a
resource
for
communicating
research
plans
and
products
within
ORD
and
with
EPA
programs,
the
regions
and
interested
parties
outside
of
EPA.
MYPs
are
updated
on
a
biennial
basis
to
provide
opportunities
for
making
the
necessary
adjustments
to
the
research
program.

As
discussed
in
the
draft
CCL
2
notice
(
69
FR
17406),
EPA
plans
to
consider
the
deferred
pesticides
in
the
context
of
an
improved
approach
for
selecting
contaminants
for
future
CCLs
(
CCL
3).
This
will
enable
the
Agency
to
consider
these
contaminants
in
a
consistent,
reproducible
manner
with
a
wide
range
of
other
contaminants.
In
this
regard,
it
is
important
to
note
that
EPA
13
may
conduct
research,
and
make
regulatory
determinations
for
any
unregulated
contaminant
not
on
today's
CCL
(
see
SDWA
section
1412(
b)(
1)(
B)(
ii)(
III)).
Thus,
the
Agency
has
the
authority
to
act
as
necessary
to
protect
public
health
as
new
information
becomes
available.

As
with
pesticides,
EPA
believes
that
suspected
endocrine
disruptors
should
be
considered
when
the
next
CCL
is
developed.
This
enables
the
Agency
to
use
a
more
refined
and
improved
approach
in
evaluating
these
contaminants.
As
previously
stated,
EPA
is
not
restricted
to
the
contaminants
on
this
CCL
for
making
regulatory
determinations.

B.
Developing
a
process
for
future
CCLs.

There
were
four
key
issues
identified
by
commenters
on
developing
a
process
for
future
CCLs.
They
are:

1.
Expert
judgement
and
transparency.

2.
The
role
of
data
quality.

3.
Simplified
approach
with
adaptive
management
applied
for
future
CCLs.

4.
The
role
of
virulence
factor
activity
relationships.

Each
of
these
issues
is
discussed
in
turn
below.

1.
Expert
judgement
and
transparency.

Comment
Summary:
Two
commenters
stated
that
there
is
a
need
for
the
CCL
process
to
be
a
transparent
process.
The
commenters
stated
that
they
view
the
transparency
of
the
CCL
14
process
as
being
critical
to
its
success
so
that
both
the
regulated
community
and
the
public
can
understand
it.
One
commenter
also
recommended
that
the
Agency
combine
expert
judgement
and
classification
algorithms
(
a
formula
or
set
of
steps
for
solving
a
particular
problem)
in
developing
the
CCL.
Classification
algorithms
or
automated
processes
should
serve
as
mechanisms
for
screening
down
the
number
of
contaminants
that
the
experts
must
then
evaluate
in
greater
depth.

Both
commenters
believe
that
the
use
of
expert
judgement
can
be
transparent
and
is
an
essential
component
to
any
future
CCL
process.
They
urged
EPA
to
clearly
define
the
role
of
expert
judgement
including
the
specific
parts
of
the
listing
process
where
it
would
be
used.

One
commenter
also
suggested
that
the
CCL
process
should
be
an
ongoing
process
within
the
Office
of
Water
and
that
the
Agency
should
actively
monitor
appropriate
peer­
reviewed
literature
for
new
contaminants,
new
methods,
and
new
health
effects
data.
In
addition,
the
Agency
should
also
increase
its
involvement
in
ongoing
symposia,
professional
meetings,
and
workshops
on
topics
relevant
to
the
CCL.

Agency's
Response:
The
Agency
agrees
with
the
commenters
that
transparency
and
use
of
expert
judgement
should
be
important
components
of
the
CCL
process.
These
recommendations
were
included
in
both
the
NRC
report
(
NRC,
2001)
and
in
the
NDWAC
Report
on
the
CCL
Classification
Process
to
the
U.
S.
Environmental
Protection
Agency
(
NDWAC,

2004).
The
Agency
received
the
NDWAC
report
in
May
of
2004
and
is
currently
evaluating
the
recommendations.

The
NRC
and
NDWAC
reports
recommend
that
the
EPA
conduct
the
CCL
process
so
that
interested
stakeholders
have
an
opportunity
to
participate
at
key
steps
in
developing
the
CCL.

Additionally
the
reports
recommend
greater
use
of
expert
judgment
and
critical
review
of
the
15
CCL
classification
process.
While
the
reports
did
not
provide
specific
advice
on
how
to
accomplish
these
recommendations
they
did
identify
key
milestones,
such
as
selecting
sources
of
data
and
developing
criteria
to
select
contaminants.
Structuring
the
process
around
such
milestones
should
enhance
transparency
and
facilitate
expert
review.

The
Agency
continues
to
evaluate
the
NDWAC
recommendation
on
how
to
include
expert
judgment
and
conduct
the
CCL
process
in
a
transparent
manner
and
will
consider
these
comments
as
future
CCLs
are
developed.

2.
The
role
of
data
quality.

Comment
Summary:
Two
commenters
stressed
the
importance
of
data
quality
in
the
CCL
process.
Both
commenters
support
the
use
of
high
quality
data
and
sound
science
in
the
CCL
process.

The
commenters
expressed
some
concern
about
the
current
quality
of
data
used
for
the
CCL
process.
The
commenters
suggested
that
EPA
should
focus
on
using
high
quality
data
that
are
appropriate
to
support
valid
characterization
of
a
contaminant
and
that
EPA
maintains
a
focus
on
data
quality
at
each
stage
of
the
CCL
process.

One
commenter
expressed
an
interest
in
participating
in
the
ongoing
development
and
application
of
a
viable
data
quality
assurance
system
that
would
support
the
data
objectives
for
each
step
in
the
CCL
process.

Agency's
Response:
The
NDWAC
recommendations
also
discussed
the
nature
and
type
of
data
and
information
used
in
the
CCL
process.
In
discussing
information
quality
16
considerations,
the
Council
noted
that
data
and
information
on
contaminants
considered
in
the
CCL
process
will
consist
of
different
types
of
data
and
that
some
contaminants
will
not
be
robustly
characterized.
The
report
also
recommends
that
while
the
Agency
should
be
explicit
about
how
it
selects
data
for
the
CCL
process,
the
process
must
have
some
flexibility
to
adequately
consider
emerging
contaminants.
As
the
Agency
develops
the
CCL
process
and
evaluates
the
NDWAC
recommendations,
it
will
consider
the
commenters'
recommendations
as
well
as
the
SDWA
data
quality
requirements.

3.
Simplified
approach.

Comment
Summary:
One
commenter
expressed
concern
over
the
NAS
and
NDWAC
recommendations
characterizing
them
as
"
a
theoretical
and
esoteric
process
and
not
a
pragmatic
process."
The
commenter
believes
that
there
is
a
need
for
the
Agency
to
develop
a
simpler,
more
streamlined
approach
that
uses
only
the
attributes
of
occurrence
and
health
effects
and
that
potentially
eliminates
some
of
the
major
complications
associated
with
the
NRC
three­
step,

fiveattribute
CCL
process,
thereby
making
the
process
more
effective
in
the
near
term.
The
NRC
approach
can
serve
as
a
useful
guide
for
the
Agency's
long­
term
CCL
development
effort;

however,
the
details
and
logistics
of
the
approach
require
additional
work.

One
commenter
was
concerned
about
the
resources
and
time
needed
to
develop
the
CCL
using
a
new
approach.
The
commenter
suggested
that
convening
a
series
of
workshops
with
external
experts
would
be
an
efficient
way
of
addressing
issues
related
to
data
quality,

contaminant
attributes,
training
sets,
process
performance,
and
protocols
for
classification
17
algorithms.

Agency's
Response:
The
NDWAC
report
provides
a
series
of
recommendations
for
the
Agency
to
consider
as
it
develops
the
CCL
process.
The
NDWAC
report
also
noted
that
the
NRC
three­
step
approach
using
five
attributes
has
merit,
but
identified
practical
limitations
or
difficulties
the
Agency
would
need
to
address.
For
example,
the
NDWAC
report
recommends
that
the
Agency
should
consider
classification
approaches
but
"
should
use
another
approach
for
selecting
contaminants
for
the
near
term
(
i.
e.,
for
CCL
3)
if
there
are
difficulties
that
cannot
be
overcome."
The
NDWAC
report
also
identifies
issues
that
the
Agency
should
consider
in
the
NRC's
recommendation
on
classification
approaches
and
emphasizes
that
the
Agency
should
consider
practical
constraints.
The
NDWAC
report
specifically
recommended
that
the
screening
step
be
as
simple
as
possible,
which
would
require
fewer
resources
and
less
time
while
adequately
identifying
those
contaminants
of
greatest
significance.
The
report
further
encouraged
the
Agency
to
consider
whether
fewer
than
the
five
attributes
used
in
the
NRC
example
of
a
classification
approach
are
adequate
for
a
new
CCL
process.
The
NDWAC
report
recognizes
that
the
Agency
will
learn
more
about
the
CCL
process
in
each
iterative
step
and
recommended
an
adaptive
management
approach
to
develop
the
CCL
process.
As
the
Agency
evaluates
the
NDWAC
recommendations,
it
will
consider
the
need
for
a
pragmatic
approach
using
available
resources
for
development
of
the
next
CCL
and
the
most
efficient
ways
to
incorporate
expert
involvement
in
the
CCL
process.

4.
The
role
of
virulence
factor
activity
relationship.
18
Comment
Summary:
A
variety
of
comments
were
received
on
the
proposed
role
of
genomic
data
and
the
VFAR
concept
for
the
CCL
process.
Most
of
the
commenters
acknowledged
that
VFAR
appears
to
be
a
powerful
and
useful
tool
that
shows
great
promise
for
future
CCL
development,
but
felt
that
the
Agency
had
not
made
clear
how
it
proposes
to
use
VFAR
technology.

The
commenters
suggested
that
the
Agency
is
placing
too
much
emphasis
on
VFAR.
One
commenter
stated
that
the
Agency
appears
to
be
relying
too
heavily
on
an
advanced
genomic
technology.
The
commenter
expressed
concerns
that
the
technology's
applications
to
environmental
samples
are
unproven
and
recommended
that
it
not
be
used
in
the
next
CCL
process.

One
commenter
suggested
that
there
are
many
unknown
variables
associated
with
the
VFAR
concept
and
it
should
therefore
be
treated
with
extreme
caution.
Two
commenters
are
concerned
that
VFAR
may
not
offer
practical
solutions
to
immediate
concerns
regarding
waterborne
disease
and
would
require
a
multi­
year
commitment
and
collaboration
by
EPA
and
other
participating
organizations
before
it
would
be
useful.

Agency
Response:
The
NRC
(
NRC,
2001)
recommendations
provided
a
detailed
discussion
of
the
potential
and
proposed
role
of
VFARs
in
the
CCL
process.
The
VFAR
principle
can
be
described
as
comparing
the
gene
structure
of
newly
identified
waterborne
pathogens
to
pathogens
with
known
genetic
structures
that
have
been
associated
with
human
disease.

Virulence
factors
are
defined
broadly
by
the
NRC
as
the
ability
of
a
pathogen
to
persist
in
the
environment,
gain
entry
into
a
host
(
e.
g.,
humans),
reproduce,
and
cause
disease
or
other
health
problems
either
because
of
its
architecture
or
because
of
its
biochemical
compounds.
A
19
number
of
virulence
factors
are
known,
including
the
ability
of
a
microbe
to
move
within
a
host
under
its
own
power,
the
ability
of
mechanisms
to
protect
the
microbe
against
the
body's
defenses
(
e.
g.,
anti­
phagocytosis
mechanisms),
the
ability
of
a
microbe
to
adhere
or
attach
to
the
surface
of
a
host
cell,
and
the
ability
of
microbes
to
produce
toxins
that
injure
host
cells.
The
NDWAC
was
specifically
charged
to
provide
an
evaluation
of
the
VFAR
approach
and
to
identify
studies
that
explore
the
feasibility
of
the
approach.
While
the
Agency
recognizes
VFAR
as
a
potential
tool
for
future
CCLs,
EPA
is
not
planning
to
solely
rely
on
the
approach
in
the
near
term
for
CCLs.
In
its
deliberation,
the
NDWAC
conducted
several
explorations
and
literature
reviews
on
the
nature
and
type
of
genomic
data
available
to
characterize
genes
that
may
be
associated
with
virulence
factors
and
an
organism's
potential
to
cause
harm.
The
reviews
and
analyses
showed
that
the
technology,

although
powerful,
still
has
serious
limitations
for
near
term
CCLs.
The
NDWAC
provided
a
series
of
pragmatic
recommendations
for
considering
pathogens
for
near
term
CCLs
and
several
recommendations
for
improving
this
process
as
genomic
technology
and
reporting
improve.
As
the
Agency
develops
the
CCL
process
for
microbes
it
will
take
these
comments
under
consideration.

V.
Developing
Future
CCLs
­
NDWAC
Recommendations
and
Next
Steps
A.
NDWAC
Recommendations.

In
the
Federal
Register
notice
of
April
2,
2004
(
69
FR
17406),
EPA
discussed
the
activities
of
the
NRC
and
the
NDWAC
related
to
the
CCL.
The
EPA
sought
the
advice
of
the
20
NRC
in
response
to
comments
received
during
the
development
of
the
1998
CCL,
which
advocated
a
broader,
more
comprehensive
approach
for
selecting
contaminants.

The
Agency
asked
the
NRC
to
address
three
key
topics
related
to
drinking
water
contaminant
selection
and
prioritization:

1.
What
approach
should
be
used
to
develop
future
CCLs?

2.
How
best
should
EPA
assess
emerging
drinking
water
contaminants
and
related
databases
to
support
future
CCL
efforts?

3.
What
approach
should
EPA
use
to
set
priorities
for
contaminants
on
the
CCL?

The
NRC's
findings
and
recommendations
on
these
topics
were
published
in
three
reports:

Setting
Priorities
for
Drinking
Water
Contaminants
(
NRC,
1999a),
Identifying
Future
Drinking
Water
Contaminants
(
NRC,
1999b),
and
Classifying
Drinking
Water
Contaminants
for
Regulatory
Consideration
(
NRC,
2001).

The
NRC
recommendations
provided
a
framework
for
evaluating
a
larger
number
of
contaminants
and
making
decisions
about
contaminants
for
which
data
are
limited
through
the
use
of
innovative
technologies
and
expert
advice.
The
EPA
requested
the
assistance
of
NDWAC
to
evaluate
and
provide
advice
on
implementing
the
NRC's
recommended
classification
process.

The
NDWAC
formed
the
CCL
Classification
Process
Work
Group
(
the
Work
Group)
and
charged
it
with
reviewing
the
NRC
2001
report.
The
Work
Group
was
asked
to
advise
the
NDWAC
on
development
and
application
of
the
classification
approach
suggested
by
the
NRC,

including
evaluating
proposed
and
alternative
methodologies.
The
Work
Group
met
10
times
from
September
of
2002
to
March
of
2004.
All
Work
Group
meetings
were
open
to
the
public
and
announced
in
the
Federal
Register.
In
conducting
its
review,
the
Work
Group
considered
the
21
large
and
growing
number
of
agents
that
might
become
candidates
for
scrutiny
in
the
CCL
process,
and
the
rapid
expansion
of
information
on
these
agents.
Based
on
this
review,
the
Work
Group
provided
the
following
recommendations:

1.
There
is
merit
in
the
three­
step
selection
process
proposed
by
NRC
for
classifying
chemical
and
microbial
contaminants.
The
NDWAC
believes
the
three­
step
process
should
involve
identification
of
the
CCL
universe,
screening
the
universe
to
a
preliminary
CCL,
and
selecting
the
CCL
from
the
Preliminary
CCL.

2.
The
NDWAC
recommends
that
the
Agency
should
move
forward
with
the
NRC
recommendation
to
develop
and
evaluate
some
form
of
prototype
classification
approach.
(
A
prototype
classification
uses
computer­
based
computational
tools
to
weigh
selected
contaminant
characteristics
against
the
characteristics
of
various
classes
of
drinking
water
contaminants
whose
occurrence
and
health
effects
are
relatively
well
understood.)

3.
The
NDWAC
believes
that
expert
judgment
plays
an
important
role
throughout
the
three­
step
selection
process,
particularly
in
reviewing
the
prototype
model
and
the
output
of
the
new
classification
approach.

4.
The
NDWAC
recommended
enhancing
the
surveillance
for
emerging
chemical
and
microbial
contaminants
and
also
soliciting
information
from
the
public
via
a
nomination
processes
to
assure
a
full
consideration
of
potential
contaminants.

The
NDWAC
also
identified
a
number
of
practical
limitations
or
difficulties
in
developing
and
applying
the
recommended
approach
and
provided
advice
on
how
these
might
be
addressed.

The
NDWAC
presented
the
final
report
to
the
Administrator
on
May
19,
2004.
The
22
report,
entitled
National
Drinking
Water
Advisory
Council
Report
on
the
CCL
Classification
Process
to
the
U.
S.
Environmental
Protection
Agency
provides
a
detailed
summary
of
the
questions
considered
by
the
NDWAC,
the
analyses
conducted
to
explore
the
questions,
key
points
discussed,
and
the
NDWAC's
recommendations
and
rationale
for
the
recommendations.
The
report
is
available
at
http://
www.
epa.
gov/
safewater/
ndwac/
council.
html.

B.
Next
Steps.

The
Agency
is
working
to
evaluate
the
NDWAC
recommendations
and
to
meet
the
statutory
deadline
to
issue
the
next
CCL.
The
NDWAC
recommendations
encourage
the
Agency
to
consider
the
practical
limitations
identified
in
their
report
and
to
use
an
adaptive
management
approach
to
develop
CCLs.
This
adaptive
management
approach
will
enable
the
Agency
to
identify
which
recommendations
can
be
implemented
for
the
next
CCL
while
learning
from
and
improving
upon
each
successive
listing
process
and
at
the
same
time
protecting
public
health.
In
its
development
of
a
new
CCL
process,
the
Agency
will
focus
on
several
areas
in
the
near
future
and
continue
to
seek
input
and
advice
from
experts
and
interested
stakeholders.
Some
of
the
key
areas
to
be
explored
in
developing
the
new
CCL
process
are
discussed
below.

The
NDWAC
recommended
that
microbial
and
chemical
contaminants
be
evaluated
by
parallel
processes
that
meet
in
the
formation
of
a
single
CCL.
The
Agency
is
developing
parallel
processes
for
microbial
and
chemical
contaminants
that
take
into
account
the
systematic
differences
in
how
these
contaminants
are
characterized
and
take
the
best
advantage
of
the
information
available
for
microbial
and
chemical
contaminants.
23
The
Agency
is
also
considering
approaches
and
opportunities
to
seek
out
and
incorporate
input
from
experts
and
interested
stakeholders
as
the
CCL
process
is
developed.
EPA
held
a
public
meeting
on
September
15,
2004,
to
provide
an
update
on
its
efforts
to
improve
upon
the
CCL
process.
The
Agency
is
also
consulting
with
interested
stakeholders
on
how
to
increase
expert
involvement
in
the
process
and
on
opportunities
to
gather
information
on
new
and
emerging
contaminants
through
professional
conferences,
focused
workshops,
and
coordination
with
other
Federal
and
State
agencies.
The
Agency
will
provide
additional
opportunities
for
the
exchange
of
information
with
the
public
before
the
next
CCL
is
proposed
in
the
Federal
Register.

The
Agency
is
evaluating
data
sources
that
characterize
a
contaminant's
potential
to
occur
in
drinking
water
and
produce
adverse
health
effect.
The
evaluation
will
consider
the
NRC
and
NDWAC
recommendations
as
well
as
SDWA
requirements
in
selecting
information
and
data
to
consider
for
the
next
CCL.
This
evaluation
will
identify
the
best
available
data
that
for
use
in
the
CCL
process
and
result
in
a
process
to
compile
information
for
a
significantly
larger
group
of
chemical
and
microbial
contaminants
than
initially
considered
for
CCL
1.

The
Agency
anticipates
conducting
analyses
to
identify
specific
criteria
related
to
occurrence
and
health
effects
associated
with
contaminants
that
could
be
used
to
select
contaminants
for
the
CCL.
The
Agency
is
evaluating
the
NDWAC
recommendation
to
develop
a
series
of
screening
criteria
that
would
identify
contaminants
for
additional
scrutiny
and
prioritization.
The
NDWAC
recommendations
provide
insight
on
the
occurrence
and
health
effects
data
that
the
Agency
could
use
to
identify
a
smaller
set
of
contaminants
for
additional
evaluation
but
does
not
recommend
specific
levels
or
criteria
to
implement
the
screening
process.

The
NDWAC
also
recommended
that
the
Agency
explore
the
use
of
classification
24
approaches
to
identify
contaminants
for
consideration
for
the
CCL.
The
Agency
is
evaluating
the
requirements
for
a
classification
approach
for
the
next
CCL
and
anticipates
seeking
additional
advice
from
experts
and
stakeholders.
EPA
will
need
to
evaluate
various
classification
approaches,
consider
the
range
of
potential
performance
indicators,
conduct
calibration
and
validation
analyses,
and
engage
experts
in
the
evaluation
of
the
selected
approach(
es)
and
associated
validation
results.

As
a
new
CCL
process
is
developed
and
implemented
for
the
next
list,
the
Agency
will
provide
updates
and
information
on
the
process.
The
CCL
process
is
a
critical
input
to
shaping
the
future
direction
of
the
drinking
water
program.
The
Agency
anticipates
that
improvements
to
the
process
will
result
in
a
more
comprehensive
approach
to
developing
the
CCL.

VI.
References
Federal
Register,
Vol.
63,
No.
40.
Announcement
of
the
Drinking
Water
Contaminant
Candidate
List;
Notice.
March
2,
1998.
10273.
(
63
FR
10273).

Federal
Register,
Vol.
69,
No.
64.
Drinking
Water
Contaminant
Candidate
List
2;
Notice.
April
2,
2004.
17406.
(
69
FR
17406).

National
Drinking
Water
Advisory
Council
(
NDWAC).
2004.
National
Drinking
Water
Advisory
Council
Report
on
the
CCL
Classification
Process
to
the
U.
S.
Environmental
Protection
Agency.
Available
at
http://
www.
epa.
gov/
safewater/
ndwac/
council.
html.

National
Research
Council
(
NRC).
1999a.
Setting
Priorities
for
Drinking
Water
Contaminants.

National
Academy
Press,
Washington,
DC
http://
www.
nap.
edu/
catalog/
6294.
html.
25
National
Research
Council
(
NRC).
1999b.
Identifying
Future
Drinking
Water
Contaminants.

National
Academy
Press,
Washington,
DC
http://
www.
nap.
edu/
catalog/
9595.
html.

NRC.
2001.
Classifying
Drinking
Water
Contaminants
for
Regulatory
Considerations.
National
Academy
Press,
Washington,
DC
http://
books.
nap.
edu/
books/
0309074088/
html/
index.
html.

USEPA.
1993.
N­
nitrosodimethylamine;
CASRN
62­
75­
9,
Integrated
Risk
Information
Service
(
IRIS).
Carcinogenicity
assessment
last
updated
July
1,
1993.
26
[
Drinking
Water
Contaminant
Candidate
List
2;
Final
Notice
­
Page
26
of
26]

Dated:

Benjamin
H.
Grumbles,

Assistant
Administrator,
Office
of
Water.
