Document ID: EPA-HQ-OW-2003-0006-0171
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2003-12-31T05:00Z

Appendix
O
Human
Health­
Based
Chemical
Selection
Process
­
2­
CONTENTS
Abbreviations
1.
INTRODUCTION
2.
OCCURRENCE
INFORMATION
3.
HUMAN
HEALTH
BENCHMARKS
4.
CHEMICAL
SELECTION
PROCESS
4.1
Availability
of
Human
Health
Benchmarks
and
Occurrence
Information
4.2
Is
the
Chemical
Already
Regulated
in
Round
One?
4.3
Chemicals
Evaluated
and
Determined
not
to
be
Hazardous
in
Sewage
Sludge
4.4
Identifying
Chemicals
with
Concentration
Values
in
U.
S.
Sewage
Sludge
4.5
Identifying
Chemicals
Occurring
in
U.
S.
Sewage
Sludge
and
with
IRIS
or
OPP
Chronic
Human
Health
Benchmarkss
4.6
Is
an
IRIS
or
OPP
Assessment
Ongoing?
4.7
Candidate
Chemicals
for
Exposure
and
Hazard
Screening
Analysis
5.
QUANTITATIVE
INFORMATION
ON
HUMAN
HEALTH
BENCHMARKS
5.1
Oral
Human
Health
Benchmarks
5.2
Inhalation
Human
Health
Benchmarks
6.
PRIORITIZATION
OF
CHEMICALS
WITH
ONGOING
ASSESSMENTS
FOR
POSSIBLE
INCLUSION
IN
A
TARGETED
SURVEY
6.1
Theoretical
Average
Daily
Intake
6.2
Comparison
of
Theoretical
Hazard
Quotients
to
Exposure
and
Hazard
Screening
Results
7.
REFERENCES
List
of
Figures
Figure
1.
Human
Health­
Based
Chemical
Selection
Process
List
of
Tables
Table
1.
Candidate
chemicals
for
sewage
sludge
screening
Table
2.
Chemicals
reported
in
sewage
sludge
and
having
human
health
benchmarks
from
a
variety
of
data
sources
Table
3.
Chemicals
regulated
in
Round
One
Table
4.
Chemicals
evaluated
and
determined
not
to
be
hazardous
in
sewage
sludge
­
3­
Table
5.
Chemicals
reported
in
U.
S.
sewage
sludge
from
literature
search
or
national
sewage
sludge
survey
and
having
human
health
benchmarks
from
a
variety
of
data
sources
Table
6.
Identifying
availability
of
IRIS
or
OPP
human
health
benchmarks
for
chemicals
occurring
in
U.
S.
sewage
sludge
Table
7.
Chemicals
occurring
in
U.
S.
sewage
sludge
and
having
IRIS
or
OPP
human
health
benchmarks
Table
8.
Chemicals
occurring
in
U.
S.
sewage
sludge
with
ongoing
health
assessments
and
existing
IRIS
or
OPP
human
health
benchmarks
Table
9.
Candidate
chemicals
for
exposure
and
hazard
screening
Table
10.
A.
Oral
human
health
benchmarks
for
candidate
chemicals
for
exposure
and
hazard
screening
Table
10.
B.
Inhalation
human
health
benchmarks
for
candidate
chemicals
for
exposure
and
hazard
screening
Table
11
Prioritization
of
chemicals
with
ongoing
health
assessments
and
IRIS
or
OPP
oral
human
health
benchmarks
Table
12
Theoretical
hazard
quotients
for
chemicals
which
qualified
for
exposure
and
hazard
screening
­
4­
Abbreviations
ATSDR
Agency
for
Toxic
Substances
and
Disease
Registry
AUR
Air
unit
risk
Cal
EPA
California
Environmental
Protection
Agency
CASRN
Chemical
Abstracts
Service
Registry
Number
CC
Critical
concentration
CWA
Clean
Water
Act
EPA
U.
S.
Environmental
Protection
Agency
FQPA
Food
Quality
Protection
Act
FY
Fiscal
year
HEAST
Health
effects
assessment
summary
tables
HHB
Human
health
benchmark
HQ
Hazard
quotient
IRED
Interim
reregistration
eligibility
decision
IRIS
Integrated
Risk
Information
System
MRL
Minimal
risk
level
NRC
National
Research
Council
NSSS
National
sewage
sludge
survey
NTP
National
Toxicology
Program
OCD
Oral
critical
dose
OPP
Office
of
Pesticide
Programs
OSF
Oral
slope
factor
OW
Office
of
Water
PAD
Population
adjusted
dose
PPRTV
Provisional
peer
reviewed
toxicity
values
RED
Reregistration
eligibility
decision
RfC
Reference
concentration
RfD
Reference
dose
TADI
Theoretical
average
daily
intake
THQ
Theoretical
hazard
quotient
UL
Tolerable
upper
intake
level
­
5­
1.
INTRODUCTION
Under
the
Clean
Water
Act,
the
U.
S.
EPA
must
periodically
review
sewage
sludge
regulations
for
the
purpose
of
identifying
additional
toxic
pollutants
for
potential
regulations.
Section
405(
d)(
2)(
C)
of
the
CWA
states:

"(
C)
Review.
)

From
time
to
time,
but
not
less
often
than
every
2
years,
the
Administrator
shall
review
the
regulations
promulgated
under
this
paragraph
for
the
purpose
of
identifying
additional
toxic
pollutants
and
promulgating
regulations
for
such
pollutants
consistent
with
the
requirements
of
this
paragraph."

As
part
of
fulfilling
this
statutory
requirement,
EPA
developed
a
screening
process
to
identify
chemicals
in
sewage
sludge
that
qualify
for
exposure
and
hazard
screening,
and
could
qualify
for
further
risk
characterization
and
potential
future
regulatory
action.
The
flowchart
for
the
entire
screening
process
is
depicted
in
Figure
1
and
a
description
of
this
screening
process
follows.

2.
OCCURRENCE
INFORMATION
EPA
conducted
an
extensive
literature
search
to
obtain
publicly
available
information
on
chemicals
that
may
occur
in
sewage
sludge,
both
at
the
national
and
international
level.
The
literature
search
covered
the
period
1990­
2002
and
identified
a
substantial
number
of
chemicals
that
were
analyzed
for
in
sewage
sludge
from
25
countries
(
Australia,
Austria,
Belgium,
Brazil,
Canada,
Cyprus,
Denmark,
Finland,
France,
Germany,
Greece,
Hong
Kong,
Italy,
Japan,
Jordan,
the
Netherlands,
Poland,
Portugal,
South
Africa,
Spain,
Sweden,
Switzerland,
Taiwan,
the
United
Kingdom
and
the
USA).
In
addition,
more
than
400
chemicals
were
monitored
in
the
1989
National
Sewage
Sludge
Survey
(
NSSS)
(
EPA,
1996;
1990).
These
were
combined
with
the
chemicals
identified
in
the
literature
search,
resulting
in
a
total
of
803
candidate
chemicals
for
the
screening
analysis.
These
chemicals
are
listed
in
Table
1
and
include
the
"
classical"
pollutants,
as
well
as
a
number
of
emerging
chemical
categories
such
as
pharmaceuticals,
brominated
flame
retardants,
and
personal­
care
products,
which
have
recently
been
identified
in
sewage
sludge.
Polychlorinated
dibenzodioxins,
polychlorinated
dibenzofurans
and
coplanar
polychlorinated
biphenyls
("
dioxins")
are
not
listed
in
Table
1
since
these
are
the
subject
of
another
Agency
review
(
EPA,
2003a).

Frequency
of
detection
is
indicated
in
Table
1
for
the
NSSS
in
three
broad
categories:
not
detected,
detected
in
1%
of
the
samples
analyzed,
or
detected
in
greater
than
1%
of
the
samples
analyzed
(
EPA,
1996;
1990).
Only
qualitative
information
("
yes"
or
"
no")
is
presented
in
Table
1
for
those
chemicals
found
in
sewage
sludge
based
on
the
national
and
international
literature
search.
­
6­
No
further
evaluation
at
this
time
(
9)

Was
the
chemical
previously
evaluated
&
determined
not
to
be
a
hazard?

Is
a
HHB
available
from
a
final
IRIS
or
OPP
assessment?
Yes
Yes
No
No
Is
an
IRIS
or
OPP
assessment
ongoing
?
Is
the
chemical
already
regulated
in
Round
One?

No
(
223)

Yes
(
79)
No
(
208)

Yes
(
61)

Yes
Figure
1.
Human
Health­
Based
Chemical
Selection
Process
(
Number
of
chemicals)

No
further
evaluation
at
this
time
(
15)

No
further
evaluation
at
this
time
(
129)
Were
measured
concentrations
in
US
sludge
reported
in
the
NSSS
or
in
the
literature
search?

No
further
evaluation
at
this
time
(
18)

Prioritize
for
possible
inclusion
in
a
targeted
survey
(
21)

Candidate
chemicals
for
exposure
and
hazard
screening
(
40)
No
(
40)
Chemicals
reported
in
sewage
sludge
&
having
HHB
from
a
variety
of
sources
(
232)
Candidate
chemicals
for
sewage
sludge
screening
(
803)
­
7­
3.
HUMAN
HEALTH
BENCHMARKS
Table
1
indicates
whether
or
not
human
health
benchmarks
(
HHBs)
are
available
for
the
803
chemicals.
HHBs
used
at
this
step
were
from
any
of
the
following
data
sources:

°
Integrated
Risk
Information
System
(
IRIS).
Health
assessments
by
IRIS
undergo
internal
(
EPA)
and
external
peer
reviews
and
are
available
on
IRIS
website
at:
http://
www.
epa.
gov/
iris/
subst/
index.
htm.
IRIS
assessments
may
include
oral
reference
doses
(
RfD)
and
inhalation
reference
concentrations
(
RfC)
for
chronic
noncarcinogenic
health
effects,
and
oral
slope
factors
(
OSF)
and
inhalation
air
unit
risks
(
AUR)
for
carcinogenic
effects.

°
Office
of
Pesticide
Programs
(
OPP)
Reregistration
Eligibility
Decisions
(
REDs)
or
Interim
Reregistration
Eligibility
Decisions
(
IREDs)
available
on
OPP
website
at:
http://
cfpub.
epa.
gov/
oppref/
rereg/
status.
cfm?
show=
rereg.
OPP
establishes
RfDs
for
chronic
and
acute
oral
exposures,
acute
and
chronic
Population
Adjusted
Doses
(
PAD)
which
take
into
account
the
Food
Quality
Protection
Act
(
FQPA)
safety
factor
for
the
protection
of
infants
and
children,
and
oral
cancer
slope
factors.
During
the
review
of
the
toxicity
data
and
the
dose­
response
assessment,
the
pesticide
being
evaluated
undergoes
review
by
several
in­
house
peer
review
committees.
Public
comments
are
also
received
on
the
health
assessments.

°
Health
Effects
Assessment
Summary
Tables
(
HEAST).
The
HEAST
is
a
database
of
human
health
toxicity
values
developed
for
chemicals
of
interest
to
Superfund,
the
Resource
Conservation
and
Recovery
Act,
and
the
EPA
in
general.
Most
of
the
toxicity
values
in
the
HEAST
are
"
provisional."
HEAST
is
not
available
on
the
Internet.

°
EPA's
Office
of
Research
and
Development,
National
Center
for
Environmental
Assessment
Provisional
Peer
Reviewed
Toxicity
Values
(
PPRTV).
PPRTVs
are
developed
for
the
EPA
Superfund
Program
to
provide
time­
critical
information
for
chemicals
that
lack
toxicity
values
on
IRIS
or
HEAST.
PPRTVs
are
not
available
on
the
Internet.

°
Agency
for
Toxic
Substances
and
Disease
Registry
(
ATSDR)
Minimal
Risk
Levels
(
MRLs)
for
non­
neoplastic
endpoints.
ATSDR
derives
MRLs
for
acute,
intermediate,
and
chronic
exposure
durations,
and
for
the
oral
and
inhalation
routes
of
exposure.
Cancer
risk
estimates
from
oral
or
inhalation
exposures
are
not
quantified.
MRLs
are
available
in
ATSDR's
Toxicological
Profiles
at:
http://
www.
atsdr.
cdc.
gov/
toxpro2.
html#­
A­.

°
California
Environmental
Protection
Agency
toxicity
values
address
both
cancer
and
noncancer
effects.
Cal
EPA
toxicity
values
are
listed
at:
http:
www.
oehha.
ca.
gov/
risk/
chemicalDB//
index.
asp.
­
8­
4.
CHEMICAL
SELECTION
PROCESS
A
series
of
screening
criteria
was
applied
to
the
master
Table
1
of
803
chemicals.
Chemicals
failing
successive
screening
steps
were
eliminated
from
further
consideration.
Each
of
these
screening
steps
is
described
below
(
see
also
Figure
1).

4.1
Availability
of
Human
Health
Benchmarks
and
Occurrence
Information
Chemicals
with
no
human
health
benchmarks
from
any
of
the
data
sources
described
in
Section
3
(
IRIS,
OPP,
PPRTV,
HEAST,
ATSDR,
Cal
EPA)
were
removed
from
consideration
since
further
hazard
screening
is
not
possible
in
the
absence
of
HHBs.
In
addition,
if
a
chemical
was
monitored
but
not
detected
in
the
NSSS
("
A"
in
that
column
in
Table
1)
and
not
reported
in
the
national
and
international
literature
search
("
no"
in
that
column
in
Table
1),
the
chemical
was
deleted
from
further
consideration,
because
it
appears
not
to
be
present
in
sewage
sludge
and
therefore
does
not
constitute
a
health
hazard.

Applying
these
two
screening
criteria
to
chemicals
listed
in
Table
1
resulted
in
the
elimination
of
571
chemicals.
The
remaining
232
chemicals
are
listed
in
Table
2.

4.2
Is
the
Chemical
Already
Regulated
in
Round
One?

Nine
metals
listed
in
Table
3
were
regulated
in
Round
One
of
the
Part
503
sewage
sludge
standards.
EPA
intends
to
assess
the
need
and
appropriate
level
for
a
numerical
standard
for
molybdenum
in
sewage
sludge
using
the
results
and
conclusions
of
a
Workshop
held
in
2000
and
supplemented
with
additional
data
developed
since
2000.
EPA
expects
to
complete
this
assessment
in
2005.
New
IRIS
health
assessments
are
ongoing
for
arsenic,
cadmium,
copper,
nickel
and
zinc.
These
new
assessments
may
influence
the
HHBs
to
be
used
for
the
exposure
and
hazard
screening
analysis.
In
addition,
EPA
plans
to
include
Round
One
metals
in
a
targeted
survey,
using
improved
analytical
techniques,
to
be
initiated
in
FY
2005.
For
these
reasons,
these
nine
metals
are,
for
the
time
being,
eliminated
from
further
consideration.

4.3
Chemicals
Evaluated
and
Determined
not
to
be
Hazardous
in
Sewage
Sludge
Table
4
lists
15
chemicals
that
are
unlikely
to
pose
a
hazard
from
their
presence
in
sewage
sludge.
Calcium
and
magnesium
are
essential
nutrients.
The
magnitudes
of
the
tolerable
upper
intake
levels
(
ULs)
for
calcium
and
magnesium
of
2.5
g/
day
and
0.35
g/
day,
respectively
(
IOM,
1999),
indicate
unlikely
hazards
from
their
presence
in
sewage
sludge.
Phthalic
anhydride
was
removed
from
consideration
because
of
its
extremely
rapid
degradation
in
soil
for
the
required
sewage
sludge
30­
day
holding
period.
Chromium
can
be
present
in
the
environment
as
chromium
III
or
the
more
toxic
chromium
VI
species.
In
sewage
sludge,
it
is
present
in
the
less
toxic
chromium
III
form
and
is
therefore
unlikely
to
present
a
hazard.
The
remaining
11
chemicals
(
aldrin,
chlordane,
DDD,
DDE,
DDT,
dieldrin,
heptachlor,
heptachlor
epoxide,
hexachlorobenzene,
lindane
and
toxaphene)
are
banned
or
severely
restricted
pesticides.
These
organochlorine
pesticides
were
­
9­
evaluated
in
1992
and
were
not
considered
to
present
a
health
hazard
from
their
presence
in
sewage
sludge
(
EPA,
1992).
Indications
are
that
concentrations
of
these
pesticides
in
sewage
sludge
are
on
the
decline
in
the
U.
S.
In
addition,
NRC
concluded
that
it
seems
highly
unlikely
that
the
banned
or
severely
restricted
chlorinated
pesticides,
at
their
level
of
occurrence
in
sewage
sludge,
will
harm
crops
or
their
consumers
(
NRC,
1996).

Except
for
lindane,
there
were
no
changes
in
oral
human
health
benchmarks
for
these
banned
or
severely
restricted
pesticides
since
their
evaluation
in
1992.
OPP's
recent
health
assessment
of
lindane
has
resulted
in
a
chronic
population
adjusted
dose
(
PAD)
of
0.0016
mg/
kg/
day
compared
to
the
1988
IRIS
RfD
of
0.0003
mg/
kg/
day
(
EPA,
1988;
2002).
Under
the
1999
draft
revised
guidelines
for
carcinogen
risk
assessment,
OPP
concluded
that
lindane
shows
suggestive
evidence
of
carcinogenicity,
but
not
sufficient
to
assess
human
carcinogenic
potential
(
EPA,
1999;
2002).
Quantitative
cancer
assessment
of
lindane
was
also
not
available
in
the
1988
IRIS
file.
The
new
OPP
health
assessment
of
lindane
will
make
it
even
less
likely
to
be
a
health
hazard
in
sewage
sludge.

For
the
above
reasons,
it
is
considered
not
necessary
to
conduct
an
exposure
screening
analysis
for
these
15
chemicals.

4.4
Identifying
Chemicals
with
Concentration
Values
in
U.
S.
Sewage
Sludge
Table
5
lists
the
remaining
208
chemicals
not
eliminated
in
the
above
described
previous
steps.
These
chemicals
were
reported
in
sewage
sludge,
and
have
human
health
benchmarks
from
a
variety
of
data
sources.

It
is
considered
appropriate
in
this
screening
exercise
to
use
only
concentration
values
found
in
U.
S.
sewage
sludge.
The
nature
and
concentration
of
chemicals
in
sewage
sludge
are
highly
dependent
on
national
laws
and
regulations
governing
the
use
of
chemicals,
and
operation
of
wastewater
treatment
plants.
Pretreatment
regulations
can
vary
significantly
from
country
to
country,
and
as
a
consequence,
the
final
repository
concentration
of
chemicals
in
sewage
sludge
will
also
vary
significantly
from
country
to
country.
Wastewater
pretreatment
regulations,
which
became
effective
in
the
U.
S.
in
1978,
have
dramatically
reduced
the
discharge
of
industrial
wastes
into
sewage
treatment
works
and
therefore
also
the
concentrations
of
industrial
chemicals
in
the
resultant
biosolids
(
NRC,
2002).
As
a
result,
chemicals
found
in
sewage
sludge
from
other
countries,
will
not
necessarily
be
found
in
sewage
sludge
in
the
U.
S.,
and
vice
versa.
In
addition,
concentration
values
for
chemicals
in
sewage
sludge,
for
example
in
Canada,
Poland,
Spain
or
the
UK,
are
highly
unlikely
to
be
representative
of
concentrations
found
in
U.
S.
sewage
sludge.
For
these
reasons,
in
this
screening
step,
only
those
concentration
values
that
have
been
measured
in
U.
S.
sewage
sludge
are
considered
appropriate
for
estimating
exposure
of
the
U.
S.
population
to
chemicals
in
sewage
sludge.

On
the
basis
of
availability
of
concentration
data
for
U.
S.
sewage
sludge,
chemicals
not
detected
or
not
monitored
in
the
NSSS
and
with
no
literature
concentration
values
in
U.
S.
sewage
sludge
were
­
10­
deleted
from
further
consideration
giving
a
list
of
79
chemicals
qualifying
for
additional
screening
(
Table
6).

4.5
Identifying
Chemicals
Occurring
in
U.
S.
Sewage
Sludge
and
with
IRIS
or
OPP
Chronic
Human
Health
Benchmarks
Table
6
also
identifies
whether
or
not
IRIS
or
OPP
chronic
HHBs
are
available
for
these
79
chemicals.

Of
the
health
assessment
databases
described
in
Section
3,
EPA
considers
that
IRIS
and
OPP
databases
are
best
suited
for
the
Agency's
potential
regulatory
activities:
human
health
benchmarks
developed
by
IRIS
or
OPP
have
received
adequate
internal
and
external
peer
reviews,
these
databases
are
readily
available
to
the
public
on
the
Internet,
provide
detailed
explanation
of
the
scientific
basis
of
the
health
assessment,
and
are
not
likely
to
change
rapidly
making
any
sewage
sludge
regulation
obsolete
before
the
next
two­
year
review
cycle.
EPA
is
therefore
using
only
IRIS
and
OPP
human
health
benchmarks
in
this
screening
process.

If
a
pesticide
has
human
health
benchmarks
from
both
IRIS
and
OPP,
OPP
health
assessment
of
a
pesticide
registered
for
food
uses
takes
precedence
over
IRIS
assessment
of
the
same
pesticide.

Of
the
79
chemicals
listed
in
Table
6,
no
IRIS
or
OPP
toxicity
values
were
available
for
17
chemicals.
Strontium
has
an
IRIS
human
health
benchmark
and
was
not
monitored
for
in
the
NSSS
but
a
mean
concentration
of
230
mg/
kg
in
U.
S.
sludge
was
reported
in
the
literature
(
Raven
and
Loeppert,
1997).
However,
available
data
on
the
environmental
properties
of
strontium
are
inadequate
to
conduct
exposure
screening
for
this
chemical.
These
18
chemicals
are
therefore
deleted
from
further
consideration.
The
remaining
61
chemicals
with
final
IRIS
or
OPP
chronic
human
health
benchmarks
qualify
for
additional
screening
and
are
listed
in
Table
7.
Table
7
also
indicates
whether
or
not
new
assessments
are
ongoing
for
these
chemicals.

4.6
Is
an
IRIS
or
OPP
Assessment
Ongoing?

IRIS
and
OPP
are
currently
conducting,
as
of
October
1,
2003,
a
detailed
review
of
recent
scientific
information
for
20
chemicals
(
EPA,
2003b,
2003c).
In
addition,
at
the
request
of
OW,
the
National
Research
Council
is
reviewing
the
toxicological,
epidemiological,
clinical,
and
exposure
data
on
orally
ingested
fluoride,
and
potential
risks
to
children.
Because
the
results
of
the
new
health
assessments
for
these
21
chemicals
with
existing
IRIS
or
OPP
HHBs
are
not
yet
available,
OW
does
not
believe
it
appropriate
to
include
these
21
chemicals,
listed
in
Table
8,
in
the
exposure
screening
analysis
at
this
time:
the
completed
health
assessments
could
result
in
significant
changes
in
the
existing
toxicity
values,
making
these
chemicals
of
more
or
less
potential
health
concerns,
and
potentially
requiring
a
change
in
rule­
making
process.
However,
OW
recognizes
that
chemicals
of
potential
health
concerns
that
are
undergoing
reevaluation
may
need
to
be
included
in
a
targeted
survey
so
that
concentration
values
in
sewage
sludge
may
be
obtained
and
used
in
future
reviews
or
screening
activities.
As
a
substitute
for
the
probabilistic
exposure
­
11­
model
used
in
the
exposure
screening
analysis,
a
simple
estimate
of
oral
exposure
was
used
to
determine
which
chemicals
with
ongoing
health
assessments
may
be
of
priority
health
concern,
and
thus
could
be
included,
subject
to
the
availability
of
adequate
budgetary
resources,
in
a
targeted
survey
to
be
initiated
in
FY
2005.
This
prioritization
scheme
is
further
described
in
Section
6
below.

4.7
Candidate
Chemicals
for
Exposure
and
Hazard
Screening
Analysis
Table
9
lists
40
chemicals
passing
all
the
screening
steps
and
qualifying
for
exposure
and
hazard
screening
using
a
probabilistic
exposure
model.
Concentrations
of
chemicals
in
U.
S.
sewage
sludge
are
needed
before
the
exposure
screening
can
proceed
for
these
40
chemicals.
The
screening
concentrations
(
mg/
kg
dry
weight
of
sludge)
used
in
this
analysis
were
the
higher
of
the
following
values:

°
The
95th
percentile
concentration
of
the
chemical
in
sewage
sludge
in
the
1989
NSSS,
or
°
The
upper
concentration
values
of
the
chemical
measured
in
U.
S.
sewage
sludge
from
the
literature
search.
Upper
concentration
values
varied
from
a
single
value
to
a
mean,
maximum
or
90th
percentile
concentrations.

Surprisingly,
only
a
limited
number
of
publications
on
chemicals
in
U.
S.
sewage
sludge
could
be
located,
postdating
the
1989
NSSS.
In
addition,
when
concentration
values
in
U.
S.
sludge
were
available
from
the
literature,
the
upper
reported
literature
concentrations
were
lower
than
those
reported
at
the
95th
percentile
level
in
the
NSSS
(
Kelley,
1997;
Raven
and
Loeppert,
1997;
Mata­
Gonzalez
et
al.
2002;
Barker,
2001;
Gutenmann
et
al.
1994).
For
this
reason,
only
the
NSSS
95th
percentile
values
are
used
in
the
exposure
screening
analysis.
Although
the
available
literature
data
are
too
limited
to
draw
any
firm
conclusions,
this
perhaps
indicates
that
concentrations
of
certain
xenobiotic
chemicals
are
on
the
decline
in
U.
S.
sewage
sludge.

5.
QUANTITATIVE
INFORMATION
ON
HUMAN
HEALTH
BENCHMARKS
IRIS
and
OPP
human
health
benchmarks
for
chronic
oral
and
inhalation
exposures,
and
for
noncancer
and
cancer
endpoints
were
used
in
this
screening
exercise.

5.1
Oral
Human
Health
Benchmarks
Chronic
RfDs
or
chronic
PADs
were
used
as
the
HHBs
for
oral
exposure
to
threshold
chemicals.
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
(
EPA,
2003e).
The
PAD
includes
an
additional
safety
factor
applied
to
the
RfD
of
up
to
ten­
fold,
if
necessary,
to
account
for
uncertainty
in
data
relative
to
children,
a
requirement
of
the
1996
FQPA
which
places
an
emphasis
on
protecting
the
health
of
infants,
children,
or
other
sensitive
individuals
exposed
to
pesticides
(
EPA,
2003f).
RfD
and
PAD
are
usually
expressed
in
mg
per
kilogram
of
body
weight
per
day
­
12­
(
mg/
kg/
day).

For
carcinogenic
chemicals,
the
oral
slope
factor
(
OSF)
is
an
upper
bound
estimate,
approximating
a
95%
confidence
limit,
on
the
increased
cancer
risk
from
a
lifetime
exposure
to
the
chemical.
This
estimate
is
usually
expressed
in
units
of
proportion
(
of
a
population)
affected
per
mg/
kg/
day
(
EPA,
2003e).
The
dose
for
a
cancer
risk
level
of
E­
5
(
1
in
100,000)
was
calculated
from
the
OSF.

The
oral
critical
dose
(
OCD)
is
the
lower
of
the
RfD,
PAD
and
dose
corresponding
to
E­
5
cancer
risk.
Table
10.
A.
lists
the
40
chemicals
together
with
their
95th
percentile
concentration
from
the
NSSS,
the
various
oral
HHBs
for
each
chemical,
and
the
OCD
used
in
subsequent
exposure
screening.

5.2
Inhalation
Human
Health
Benchmarks
Inhalation
RfCs
are
established
for
threshold
chemicals.
The
RfC
is
an
estimate
(
with
uncertainty
spanning
perhaps
an
order
of
magnitude)
of
a
continuous
inhalation
exposure
to
the
human
population
(
including
sensitive
subgroups)
that
is
likely
to
be
without
an
appreciable
risk
of
deleterious
effects
during
a
lifetime
(
EPA,
2003e).
RfCs
are
usually
expressed
in
units
of
mg/
m3.
OPP
does
not
establish
RfCs
for
pesticides
since
the
margin
of
exposure
(
MOE)
approach
is
used
for
characterization
of
risk
via
the
inhalation
exposure.
However,
for
this
exercise,
OPP
derived
"
equivalent"
inhalation
benchmarks
for
azinphos
methyl,
chlorpyrifos,
diazinon
and
naled,
based
on
information
contained
in
the
IREDs
for
these
pesticides
(
OPP,
2003).

For
carcinogenic
chemicals,
the
air
unit
risk
(
AUR)
is
the
95%
upper
bound
excess
lifetime
cancer
risk
estimated
to
result
from
continuous
exposure
to
the
chemical
at
a
concentration
of
1
mg/
m3
in
air
(
EPA,
2003e).
The
air
concentration
associated
with
a
risk
level
of
E­
5
(
1
in
100,000)
was
calculated
from
the
AUR.

The
inhalation
critical
concentration
(
CC)
is
the
lower
of
the
RfC
and
concentration
for
E­
5
cancer
risk.
Table
10.
B.
lists
the
40
chemicals
together
with
their
95th
percentile
concentration
from
the
NSSS,
the
oral
critical
dose
determined
in
Table
10.
A,
IRIS
RfCs
or
OPP­
derived
"
equivalent"
inhalation
benchmarks,
IRIS
concentration
corresponding
to
E­
5
cancer
risk,
and
the
CC
used
in
subsequent
exposure
screening.

6.
PRIORITIZATION
OF
CHEMICALS
WITH
ONGOING
ASSESSMENTS
FOR
POSSIBLE
INCLUSION
IN
A
TARGETED
SURVEY
As
a
substitute
for
the
EPA
probabilistic
exposure
model,
a
simple
estimate
of
exposure
is
used
to
determine
which
chemicals
listed
in
Table
8
with
ongoing
health
assessments
at
October
1,
2003,
may
be
of
priority
health
concern,
and
thus
could
be
included
in
the
targeted
survey,
to
be
initiated
in
FY
2005.
6.1
Theoretical
Average
Daily
Intake
­
13­
An
estimate
of
"
Theoretical
Average
Daily
Intake"
(
TADI)
is
made
using
the
exposure
scenario
of
a
1­
3
year
old
child,
one
of
the
most
highly
exposed
population
group
on
a
kg
body
weight
basis.
The
following
assumptions
are
made:

°
Child
body
weight
is
13
kg
(
EPA,
1997a);
°
Total
daily
diet
consumed
by
child
consists
of
0.8
kg
food
(
EPA,
1997b)
and
0.3
kg
drinking
water
(
EPA,
2000);
°
The
average
concentration
(
C
avg)
in
mg/
kg
of
sludge
(
dry
weight
basis)
of
the
chemical
is
assumed
to
be
entirely
translocated
to
the
daily
total
diet
of
1.1
kg.

TADI,
mg/
kg/
day
=
C
avg
x
1.1
13
TADIs
calculated
in
this
manner
are
based
on
conservative
assumptions
and
are,
in
effect,
equivalent
to
the
daily
consumption
of
1.1
kg
of
dried
sewage
sludge
containing
average
concentration
of
the
chemical
under
consideration.

A
Theoretical
Hazard
Quotient
(
THQ)
is
then
derived.
The
THQ
is
the
ratio
of
the
TADI
to
the
oral
critical
dose
(
OCD),
where
the
OCD,
in
mg/
kg/
day,
is
the
lower
of
the
reference
dose,
population
adjusted
dose,
or
dose
for
10­
5
cancer
risk,
i.
e.,

THQ
=
TADI
OCD
The
THQs
have
been
calculated
for
each
of
the
20
chemicals
with
ongoing
health
assessments
and
with
IRIS
or
OPP
existing
oral
human
health
benchmarks.
These
THQs
are
given
in
Table
11
and
are
sorted
in
decreasing
order.

6.2
Comparison
of
Theoretical
Hazard
Quotients
to
Exposure
and
Hazard
Screening
Results
Forty
chemicals
qualified
for
exposure
and
hazard
screening
using
the
EPA
probabilistic
exposure
model.
Hazard
quotients
(
HQ)
have
been
calculated
for
these
chemicals
(
EPA,
2003d).
The
HQ
is
the
ratio
of
the
estimated
exposure
derived
using
the
probabilistic
model,
to
the
oral
critical
dose
(
OCD),
where
the
OCD,
in
mg/
kg/
day,
is
the
lower
of
the
reference
dose,
population
adjusted
dose,
or
dose
corresponding
to
10­
5
cancer
risk.
Chemicals
"
failing"
the
exposure
screen
for
oral
exposure
i.
e.,
with
HQ
greater
than
one
are
barium,
4­
chloroaniline,
manganese,
nitrate,
nitrite
and
silver
(
EPA,
2003d).
Theoretical
hazard
quotients
(
THQs)
were
also
calculated
for
these
40
chemicals
and
are
listed
in
Table
12.
It
can
be
seen
from
Table
12
that
the
six
chemicals
having
HQ
>
1
always
had
THQs
equal
to
or
greater
than
75
using
the
TADI
approach.

On
this
basis,
a
prioritization
scale
was
established
for
the
20
chemicals
with
ongoing
health
assessments
and
IRIS
or
OPP
oral
human
health
benchmarks:
­
14­
THQ

75:
High
priority
chemicals
for
inclusion
in
the
targeted
survey.

THQ
<
75:
Low
priority
chemicals
Using
this
priority
scale,
chemicals
with
THQs
equal
to
or
greater
than
75
are
high
priority
chemicals
of
potential
health
concern
and
could
be
included,
subject
to
the
availability
of
adequate
budgetary
resources,
in
the
targeted
survey
to
be
initiated
in
FY
2005.
These
are
benzo[
a]
pyrene,
polychlorinated
biphenyl
congeners
and
Aroclors
(
excluding
coplanar
PCB
congeners
already
included
in
the
2001
dioxins
survey),
di(
2­
ethylhexyl)
phthalate,
thallium,
antimony,
carbon
tetrachloride
and
fluoride.
Chemicals
with
THQs
less
than
75
are
considered
of
low
priority
and
are
not
planned
to
be
included
in
the
survey.

Inhalation
exposure
was
not
included
in
this
theoretical
estimation
of
exposure
since
in
all
cases
of
application
of
the
probabilistic
exposure
model,
the
inhalation
route
of
exposure
was
negligible
(
EPA,
2003d).

Priority
for
inclusion
or
exclusion
of
chemicals
with
ongoing
health
assessments
in
the
planned
survey
will
be
reconsidered
if
the
results
of
ongoing
IRIS,
OPP
or
NRC
assessments
become
available
and
indicate
a
different
priority
order.

7.
REFERENCES
Barker
AV.
2001.
Evaluation
of
Compost
for
Growth
of
Grass
Sod.
Commun.
Soil
Sci.
Plant
Anal.,
32
(
11
and
12),
1841­
1860.

EPA
(
U.
S.
Environmental
Protection
Agency).
1988.
IRIS
Summary
for
Gamma­
Hexachlorocyclohexane
(
Gamma­
HCH).
Available
at:
http://
www.
epa.
gov/
iris/
subst/
0065.
htm
EPA.
1990.
National
Sewage
Sludge
Survey;
Availability
of
Information
and
Data,
and
Anticipated
Impacts
on
Proposed
Regulations;
Proposed
Rule.
Federal
Register
Vol.
55,
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