Document ID: EPA-HQ-OPP-2006-0156-0007
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2006-04-19T04:00Z

Page
1
of
12
March
23,
2006
MEMORANDUM
SUBJECT:
Inert
Ingredient
Dietary
Risk
Assessment
for
Linear
Alkyl
Benzenesulfonate
Reregistration
Eligibility
Document
(
RED)
Registration
RED­
4006­
26242
DP#
324036
FROM:
Kerry
Leifer
Inert
Ingredient
Assessment
Branch
Registration
Division
(
7505C)

TO:
Jennifer
Slotnick,
Chemical
Review
Manager
RM
Team
36
Regulatory
Management
Branch
II
Antimicrobials
Division
(
7510C)

and
Deborah
Smegal
Reregistration
Branch
I
Health
Effects
Division
(
7509C)

As
part
of
the
overall
risk
assessment
for
Reregistration
Case
No.
4006:
benzenesulfonic
acid,
dodecyl­
(
CAS
Reg.
No.
27176­
87­
0);
sodium
dodecylbenzenesulfonate
(
CAS
Reg.
No.
25155­
30­
0);
and
benzenesulfonic
acid,
C10­
16­
alkyl
derivs.
(
CAS
Reg.
No.
68584­
22­
5),
exposures
resulting
from
the
active
ingredient
use
of
these
substances
(
referred
to
throughout
this
document
as
"
linear
alkylbenzenesulfonates")
are
aggregated
with
exposures
resulting
from
the
use
of
the
linear
alkylbenzenesulfonates
as
inert
ingredients.
This
memorandum
includes
an
assessment
of
dietary
exposures
(
including
both
food
and
drinking
water)
for
the
inert
ingredient
uses
of
benzenesulfonic
acid,
dodecyl­
(
CAS
Reg.
No.
27176­
87­
0);
sodium
dodecylbenzenesulfonate
(
CAS
Reg.
No.
25155­
30­
0);
and
benzenesulfonic
acid,
C10­
16­
alkyl
derives.
(
CAS
Reg.
No.
68584­
22­
5)
to
be
utilized
for
reregistration
risk
assessment
purposes.

Background
Benzenesulfonic
acid,
dodecyl­
(
CAS
Reg.
No.
27176­
87­
0);
sodium
dodecylbenzenesulfonate
(
CAS
Reg.
No.
25155­
30­
0);
and
benzenesulfonic
acid,
C10­
UNITED
STATES
ENVIRONMENTAL
PROTECTION
AGENCY
WASHINGTON,
D.
C.
20460
OFFICE
OF
PREVENTION,
PESTICIDES,
AND
TOXIC
SUBSTANCES
Page
2
of
12
16­
alkyl
derives.
(
CAS
Reg.
No.
68584­
22­
5)
each
have
use
as
pesticide
inert
ingredients
(
surfactants)
in
a
number
of
food
use
and
nonfood
use
pesticide
products.
In
the
case
of
the
food
uses
of
these
substances,
their
food
residues
are
considered
exempt
from
the
requirement
of
a
tolerance
based
on
these
substances
being
part
of
a
group
of
alkyl
benzenesulfonates
for
which
an
exemption
from
the
requirement
of
a
tolerance
exists
under
the
40
CFR
§
180.910
and40
CFR
§
180.930
listings
of
"
Alkyl
(
C8­
C24)
benzenesulfonic
acid
and
its
ammonium,
magnesium,
potassium,
sodium,
and
zinc
salts"
summarized
in
Table
1
below.

Table
1.
Tolerance
Exemptions
for
Linear
Alkylbenzensulfonates
as
Inert
Ingredients
Tolerance
Exemption
Expression/
Chemical
Name
CAS
Reg.
No.
40
CFR
§
180.
Use
Pattern
(
Pesticidal)

910
Surfactants,
related
adjuvants
of
surfactants
Alkyl
(
C8­
C24)
benzenesulfonic
acid
and
its
ammonium,
calcium,
magnesium,
potassium,
sodium,
and
zinc
salts.
­­­

930
Surfactants,
emulsifier,
related
adjuvants
of
surfactants
Inert
Ingredient
Dietary
Risk
Assessment
for
Linear
Alkyl
Benzenesulfonate
A.
Exposure
Assumptions
A
dietary
exposure
analysis
for
the
inert
ingredient
use
of
linear
alkyl
benzenesulfonate
(
benzenesulfonic
acid,
dodecyl­
(
CAS
Reg.
No.
27176­
87­
0);
sodium
dodecylbenzenesulfonate
(
CAS
Reg.
No.
25155­
30­
0);
and
benzenesulfonic
acid,
C10­
16­
alkyl
derivs
(
CAS
Reg.
No.
68584­
22­
5))

The
dietary
(
food)
assessment
was
conducted
using
the
generic
screening
model
for
estimating
inert
ingredient
dietary
exposure
as
a
basis
for
estimating
linear
alkyl
benzenesulfonate
dietary
exposure.
This
form
of
assessment
is
unrefined
and
extremely
conservative
in
nature
as
the
screening
model
assumes
that
the
inert
ingredient
is
used
on
all
commodities,
and
that
100
percent
of
crops
are
treated
with
the
inert
ingredient.
Further,
the
model
assumes
finite
residues
for
every
consumed
commodity
(
including
meat,
milk,
poultry
and
eggs)
that
is
included
in
the
Dietary
Exposure
Evaluation
Model
(
DEEM
 
)
.
A
complete
explanation
of
the
assumptions
used
in
the
generic
screening
model
for
estimating
inert
ingredient
dietary
exposure
is
given
in
Appendix
A.

The
drinking
water
exposure
analysis
is
based
on
a
derivation
of
estimated
upper
bound
drinking
water
concentrations
from
these
substances'
use
as
pesticide
inert
ingredients
from
the
FQPA
Index
Reservoir
Screening
Tool
(
FIRST).
The
results
of
the
FIRST
modeling
analysis
and
the
conservative
assumptions
utilized
as
inputs
into
the
inert
ingredient
drinking
water
exposure
assessment
model
are
provided
in
Appendix
B.
Page
3
of
12
B.
Dietary
Risk
from
Food
Based
on
the
toxicity
endpoints
selected
by
the
Toxicity
Advisory
Clinic
(
TAC)
in
its
meeting
of
January
8,
2006,
a
dietary
risk
assessment
was
conducted
for
the
inert
ingredient
linear
alkyl
benzenesulfonate.
The
TAC
did
not
select
an
endpoint
for
acute
dietary
exposures
as
no
effects
are
attributable
to
a
single
dose,
therefore
acute
dietary
(
food)
risk
estimate
for
the
inert
ingredient
use
of
linear
alkyl
benzenesulfonate
was
not
performed.
The
TAC
selected
an
endpoint
for
chronic
dietary
exposure
to
linear
alkyl
benzenesulfonate
of
0.5
mg/
kg/
day
(
cPAD=
0.5
mg/
kg/
day).
The
table
below
(
Table
2)
provides
a
summary
of
the
results
of
chronic
dietary
risk
estimates
for
the
inert
ingredient
use
of
linear
alkyl
benzenesulfonate.

Table
2.
Estimated
Chronic
Dietary
Exposure
for
Linear
Alkyl
Benzenesufonate
(
LABS)
Population
Subgroup1
Generic
Estimated
Exposure,
mg/
kg/
day
LABS
Estimated
Exposure,
mg/
kg/
day
%
cPAD
U.
S.
Population
(
total)
0.120
0.1200
­
24%
All
infants
(<
1
year)
0.245
0.2450
­
49%
Children
(
1­
2
years)
0.422
0.4220
­
84%
Children
(
3­
5
years)
0.310
0.3100
­
62%
Children
(
6­
12
years)
0.174
0.1740
­
35%
Youth
(
13­
19
years)
0.100
0.1000
­
20%
Adults
(
20­
49
years)
0.087
0.0870
­
17%
Adults
(
50+
years)
0.086
0.0860
­
17%
Females
(
13­
49
years)
0.087
0.0870
­
17%

1Only
representative
population
subgroups
are
shown.

Rev
01/
25/
06
cPAD
0.5
C.
Dietary
Risk
from
Drinking
Water
A
January
18,
2006,
memorandum
from
Talia
Milano
to
Jennifer
Slotnick
and
Deborah
Smegal
entitled
"
Environmental
Fate
Assessment
of
Alkylbenzene
Sulfonates
for
the
Registration
Eligibility
Document
(
RED)"
provided
information
on
the
environmental
fate
of
linear
alkyl
benzenesulfonates.
Based
on
information
presented
in
that
assessment,
linear
alkyl
benzenesulfonates
are
water
soluble,
nonvolatile
and
mobile,
but
also
readily
biodegradable.
There
are
no
readily
available
data
on
the
occurrence
of
linear
alkyl
benzenesulfonates
in
ambient
or
treated
drinking
water.
No
ambient
water
quality
criteria,
drinking
water
maximum
contaminant
levels
or
health
advisory
levels
have
been
established
for
these
compounds
by
EPA's
Office
of
Water.
The
potential
for
transport
into
drinking
water
resulting
from
pesticide
inert
ingredient
uses
of
these
substances
do
Page
4
of
12
exist,
therefore
an
estimate
of
drinking
water
concentrations
resulting
from
the
inert
ingredient
uses
of
these
substances
was
conducted.

As
noted
above,
the
TAC
did
not
select
an
endpoint
for
acute
dietary
exposures
as
no
effects
are
attributable
to
a
single
dose,
therefore
an
acute
drinking
water
risk
estimate
for
the
inert
ingredient
use
of
linear
alkyl
benzenesulfonate
was
not
performed.
The
estimated
chronic
drinking
water
concentration
and
drinking
water
level
of
concern
for
chronic
exposure
to
linear
alkyl
benzenesulfonates
is
given
in
Table
3
below.

Table
3.
Chronic
Drinking
Water
Exposure
Estimates
for
Inert
Ingredient
Uses
of
Linear
Alkyl
Benzenzesulfonates
Population
Subgroup
EDWC1
(
µ
g/
L)
DWLOC2
(
µ
g/
L)
U.
S.
Population
(
total)
6.6
38
­
1,500
Children
(
1­
2
years)
6.6
8
­
500
1
Estimated
Drinking
Water
Concentration
(
EDWC)
for
chronic
drinking
water
exposure
as
determined
by
the
use
of
FIRST
modeling
analysis
described
above.
[
The
EDWC
for
linear
alkyl
benzenesulfonates
is
the
value
reported
as
the
"
Adjusted
Annual
Average
(
Chronic)
Untreated
Water
Concentration"
in
Appendix
B]
2
Drinking
Water
Level
of
Comparison
(
DWLOC)
is
the
maximum
contribution
from
water
allowed
in
the
diet.
In
this
case,
since
the
allowable
risk
contribution
from
food
is
based
on
a
screening
level
model,
the
use
of
a
single,
deterministic
value
for
the
DWLOC
is
not
appropriate.
Rather
a
DWLOC
range
is
given,
with
the
values
in
the
range
corresponding
to
an
upper
value
of
range
of
drinking
water
concentrations
ranging
from
100%
of
the
cPAD
(
i.
e.,
assuming
no
food
exposure)
to
a
lower
value
that
considers
food
exposures
to
be
at
the
dietary
screening
level
value.

D.
Conclusions
Based
on
the
use
of
the
screening
level
inert
ingredient
dietary
exposure
model
and
the
selected
chronic
dietary
exposure
endpoint
for
linear
alkyl
benzenesulfonates,
there
are
no
concerns
for
risks
associated
with
dietary
(
food)
exposures
as
the
estimated
dietary
exposures
for
the
U.
S.
population
and
all
population
subgroups
are
below
100%
of
the
cPAD.
It
should
again
be
noted
that
this
screening
level
dietary
risk
assessment
is
quite
conservative
in
nature,
and
that
the
dietary
exposure
to
linear
alkyl
benzenesulfonates
as
inert
ingredients
in
pesticide
products
estimated
herein
would
greatly
exceed
actual
dietary
exposures
as
the
uses
and
effective
application
rates
of
linear
alkyl
benzenesulfonates1
as
inert
ingredients
applied
to
crops
are
far
less
than
those
uses
and
application
rates
utilized
in
the
screening
model.

1
A
survey
of
those
products
listed
as
containing
the
inert
ingredients
benzenesulfonic
acid,
dodecyl­
(
CAS
Reg.
No.
27176­
87­
0);
sodium
dodecylbenzenesulfonate
(
CAS
Reg.
No.
25155­
30­
0);
and
benzenesulfonic
acid,
C10­
16­
alkyl
derivs
(
CAS
Reg.
No.
68584­
22­
5)
was
conducted.
The
results
of
that
survey
indicate
that
the
use
of
linear
alkylbenzenesulfonates
as
inert
ingredients
is
limited,
as
nearly
all
products
that
do
contain
linear
alkylbenzenesulfonates
as
inert
ingredients
have
a
total
linear
alkyl
benzenesulfonate
content
of
less
than
5%
w/
w.
Additionally,
the
vast
majority
of
the
products
that
contain
linear
alkyl
benzene
sulfonates
are
herbicide
products
that
typically
are
applied
in
a
preemergent
or
early
post­
emergent
fashion,
use
scenarios
that
result
in
little
or
no
crop
residues.
Page
5
of
12
For
chronic
drinking
water
exposures
to
linear
alkyl
benzenesulfonates
as
inert
ingedients,
the
DWLOC
range
for
chronic
exposure
is
38­
1500
µ
g/
L
for
the
general
U.
S.
population
and
8­
500
µ
g/
L
for
children
1­
2
years
old.
The
EDWC
used
to
assess
chronic
(
non­
cancer)
dietary
risk
from
drinking
water
is
6.6
µ
g/
L.
The
chronic
estimated
concentration
is
below
the
DWLOCs
for
the
general
U.
S.
population
and
all
population
subgroups.
Drinking
water
risks,
therefore,
are
not
of
concern.

Based
on
the
use
of
screening
level
inert
ingredient
dietary
exposure
model
and
the
selected
chronic
dietary
exposure
endpoint
for
linear
alkyl
benzenesulfonates
as
well
as
the
estimated
upper
bound
drinking
water
concentrations
from
these
substances'
use
as
pesticide
inert
ingredients
derived
from
FIRST,
there
are
no
concerns
for
aggregate
dietary
and
drinking
water
exposures
to
linear
alkyl
benzenesulfonates
resulting
from
their
use
as
pesticide
inert
ingredients.
Page
6
of
12
APPENDIX
A
Dietary
Exposure
Model
for
Inert
Ingredients
A
screening
level
model
for
predicting
dietary
(
food)
exposure
to
inert
ingredients
was
developed
and
is
based
on
the
following
assumptions
and
inputs:

Model
Assumptions
Actual
crop­
specific
residue
data
for
active
ingredients
can
be
utilized
as
surrogate
data
for
inert
ingredient
residue
levels
(
including
secondary
residues
in
meat,
milk,
poultry
and
eggs).

Inert
ingredients
are
used
on
all
crops
and
100%
of
all
crops
are
"
treated"
with
inert
ingredients
No
adjustment
made
for
%
of
inert
in
formulation,
application
rate,
or
multiple
applications
of
different
active
ingredient
formulations
Considers
only
preharvest
applications
Model
Inputs
A
group
of
57
of
the
most
"
significant"
active
ingredients
were
considered.
These
active
ingredients
included
substances
in
the
insecticide
(
20)
,
fungicide
(
17),
and
herbicide
class
(
20)
and
were
selected
based
on
a
overall
ranking
scheme
that
included
the
following
components:
Overall
Use 
Based
on
1999
data
for
active
ingredient
use
(
in
lbs/
yr).
(
All
herbicides
at
>
5
million
lbs/
yr
and
all
fungicides
and
insecticides
at
>
1
million
lbs/
yr
were
included)
Use
on
crops
that
are
significant
contributors
to
diet
(
All
a.
i.
s
which
had
substantial
use
on
crops
that
make
up
the
"
Top
25"
kids
diet
were
included).
Use
on
specific
crops
(
crop­
by­
crop
pesticide
use
information
was
evaluated
to
identify
the
most
frequently
used
active
ingredients)
Actual
residue
monitoring
studies
(
active
ingredients
with
the
highest
frequency
of
detection)

Model
Construct
A
DEEM
 
­
type
analysis
was
performed
utilizing
the
highest
established
tolerance
level
residue
for
each
commodity.
In
those
cases
where
DEEM
listed
a
commodity
for
which
a
published
tolerance
did
not
exist,
the
input
value
was
selected
based
on
representative
crops
or
other
"
default"
values
(
e.
g,
use
of
standard
processing
factors).
A
DEEM­
FCID
 
,
Version
1.3
analyses
were
performed
for
both
acute
and
chronic
dietary
exposure
scenarios
and
the
results
for
each
are
given
in
Table
1
and
2.
Page
7
of
12
DEEM­
FCID
 
Program
and
Consumption
Information
Generic
inert
ingredient
acute
and
chronic
dietary
exposure
assessments
were
conducted
using
the
Dietary
Exposure
Evaluation
Model
software
with
the
Food
Commodity
Intake
Database
(
DEEM­
FCID
 
,
Version
1.3),
which
incorporates
consumption
data
from
USDA's
Continuing
Surveys
of
Food
Intakes
by
Individuals
(
CSFII),
1994­
1996
and
1998.
The
1994­
96
and
998
CSFII
data
are
based
on
the
reported
consumption
of
more
than
20,000
individuals
over
two
non­
consecutive
survey
days.
Foods
"
as
consumed"
(
e.
g.,
apple
pie)
are
linked
to
EPA­
defined
food
commodities
(
e.
g.
apples,
peeled
fruit
­
cooked;
fresh
or
N/
S;
baked;
or
wheat
flour
­
cooked;
fresh
or
N/
S,
baked)
using
publicly
available
recipe
translation
files
developed
jointly
by
USDA/
ARS
and
EPA.
Consumption
data
are
averaged
for
the
entire
U.
S.
population
and
within
population
subgroups
for
chronic
exposure
assessment,
but
are
retained
as
individual
consumption
events
for
acute
exposure
assessment.

For
chronic
exposure
and
risk
assessment,
an
estimate
of
the
residue
level
in
each
food
or
food­
form
(
e.
g.,
orange
or
orange
juice)
on
the
food
commodity
residue
list
is
multiplied
by
the
average
daily
consumption
estimate
for
that
food/
food
form.
The
resulting
residue
consumption
estimate
for
each
food/
food
form
is
summed
with
the
residue
consumption
estimates
for
all
other
food/
food
forms
on
the
commodity
residue
list
to
arrive
at
the
total
average
estimated
exposure.
Exposure
is
expressed
in
mg/
kg
body
weight/
day.
This
procedure
is
performed
for
each
population
subgroup.

For
acute
exposure
assessments,
individual
one­
day
food
consumption
data
are
used
on
an
individual­
by­
individual
basis.
The
reported
consumption
amounts
of
each
food
item
can
be
multiplied
by
a
residue
point
estimate
and
summed
to
obtain
a
total
daily
pesticide
exposure
for
a
deterministic
(
Tier
1
or
Tier
2)
exposure
assessment,
or
"
matched"
in
multiple
random
pairings
with
residue
values
and
then
summed
in
a
probabilistic
(
Tier
3/
4)
assessment.
For
this
screening­
level
assessment,
only
a
Tier
1
analysis
was
performed.

Use
of
Model
in
Inert
Risk
Assessment
The
results
of
this
model
would
likely
represent
an
upper­
bound
estimate
of
likely
potential
dietary
exposure
to
an
inert
ingredient
resulting
from
preharvest
use.
These
values
could
be
compared
to
the
expected
toxicity
in
a
qualitative
(
Tier
1
substance)
assessment,
or,
in
those
cases
where
a
bounding
level
risk
assessment
is
necessary,
these
exposure
values
could
be
compared
to
the
selected
toxicity
endpoints
in
a
%
PAD
or
MOE
type
approach
(
see
Figure
1).
In
cases
where
this
model
would
yield
dietary
risk
values
below
the
level
of
concern,
no
further
refinements
would
be
necessary,
and
the
potential
dietary
exposure
and
risk
could
be
considered
adequately
characterized.
If
this
model
results
in
dietary
risk,
above
the
level
of
concern,
then
additional
data,
use
limitations,
and/
or
/
further
refinements
would
be
necessary.
Additionally,
the
use
of
this
model
could
allow
apportionment
of
the
amount
of
remaining
`
acceptable'
risk
to
other
routes
of
exposure.
Page
8
of
12
Fictional
Example
of
Use
of
Dietary
Exposure
Model
in
%
PAD
Approach
Dose
selected=
500
mg/
kg­
bw/
day
Uncertainty
factor=
1000
cPAD=
0.5
mg/
kg­
bw/
day
Dietary
exposure=
0.12
mg/
kg/
day
%
cPAD=
0.12
mg/
kg/
day/
0.5
mg/
kg­
bw/
day
x100
=
24
Model
Limitations
and
Areas
for
Further
Consideration
Actual
inert
ingredient
residue
levels­­
While
the
selected
group
of
active
ingredients
possesses
some
chemical
structural
diversity,
could
inert
ingredients
(
by
virtue
of
their
uptake
into
plants
and
environmental
persistence)
differ
greatly
from
active
ingredients
in
terms
of
the
nature
and
magnitude
of
their
plant
and
animal
residues?
What
about
degradates 
would
they
be
of
concern
or
need
to
be
separately
assessed?
Concentration
of
inert
in
formulation­­
Initial
analysis
of
"
benchmark"
products
for
many
of
the
57
most
"
significant"
active
ingredients
indicates
that
the
concentration
of
the
a.
i
$

any
single
inert
ingredient.
If
this
can
be
further
confirmed,
it
may
allow
for
a
"
maximum
%
inert"
adjustment
to
be
used
in
the
model.
Differences
in
product
use
rate
and
impacts
on
residue
level.­­
While
there
are
a
few
outliers,
most
of
these
a.
i.'
s
are
used
in
the
1­
5
lb
(
AI
basis)
per
season
use
rate.
"
Generic"
inert 
The
model
makes
no
distinction
as
to
formulation
type
or
timing
of
application.
It
may
be
possible
to
develop
other
models
for
more
specific
inert
use
(
e.
g.,
preemergent
use
only,
soil
incorporation
only).
Residues
in
meat,
milk,
poultry
and
eggs 
This
model
used
the
highest
tolerance
level
residues
for
input
into
DEEM
 
,
but
it
may
be
possible
to
utilize
residues
in
livestock
feed
items
and
chemical
specific
information
related
to
uptake
or
accumulation
of
secondary
residues
develop
a
different
set
of
values
on
a
per
inert
basis
for
meat,
milk,
poultry
and
eggs.

Table
1.
Estimated
Chronic
Dietary
Exposure1
for
a
Generic
Inert
Population
Subgroup2
Estimated
Exposure,
mg/
kg/
day
U.
S.
Population
(
total)
0.12
All
infants
(<
1
year)
0.245
Children
(
1­
2
years)
0.422
Children
(
3­
5
years)
0.31
Children
(
6_
12
years)
0.174
Youth
(
13­
19
years)
0.1
Adults
(
20­
49
years)
0.087
Adults
(
50+
years)
0.086
Females
(
13_
49
years)
0.087
1Exposure
estimates
are
based
on
highest­
tolerance­
level
residues
of
high­
use
active
ingredients
for
all
food
forms,
including
meat,
milk,
poultry,
and
eggs.

2
Only
representative
population
subgroups
are
shown.
Page
9
of
12
Table
2.
Estimated
Acute
Dietary
Exposure1
for
a
Generic
Inert.

Population
Subgroup2
Estimated
Exposure,
mg/
kg/
day
95th
Percentile
99th
Percentile
99.9th
Percentile
U.
S.
Population
(
total)
0.336
0.643
1.164
All
infants
(<
1
year)
0.701
1.06
2.056
Children
(
1­
2
years)
0.939
1.382
2.106
Children
(
3­
5
years)
0.683
1.01
1.476
Children
(
6_
12
years)
0.395
0.563
0.827
Youth
(
13­
19
years)
0.239
0.357
0.815
Adults
(
20­
49
years)
0.199
0.295
0.468
Adults
(
50+
years)
0.191
0.263
0.357
Females
(
13_
49
years)
0.198
0.287
0.415
1Exposure
estimates
are
based
on
highest­
tolerance­
level
residues
of
high­
use
active
ingredients
for
all
food
forms,
including
meat,
milk,
poultry,
and
eggs.

2
Only
representative
population
subgroups
are
shown.
Page
10
of
12
APPENDIX
B
Estimated
Environmental
Concentration
(
EEC)
of
Linear
Alkyl
Benzenesulfonates
in
Untreated
Drinking
Water
and
Surface
Water
Resulting
from
Use
as
Inert
Ingredients
I.
Drinking
Water
Monitoring
data
were
not
available
for
surface
or
ground
water,
therefore
modeling
was
performed.
In
the
absence
of
measured
chemical
properties,
known
fate
and
transformation
half­
lives,
and
actual
use
and
usage
information,
Tier
I
models
provide
a
conservative
assessment
of
exposures
in
which,
under
almost
all
conditions,
are
unlikely
to
be
exceeded.
In
addition,
proper
parameterization
of
higher
tier
models
necessitates
measured
fate
and
known
usage
data.
Drinking
water
exposures
were
estimated
using
the
Tier
I
surface
water
exposure
model
FQPA
Index
Reservoir
Screening
Tool
(
FIRST,
Version
1.0,
dated
August
1,
2001).
The
Tier
I
ground
water
exposure
model,
Screening
Concentrations
in
Ground
Water,
was
not
used
in
this
assessment
because
these
compounds
are
unlikely
to
result
in
exposures
exceeding
surface
waster
concentrations
when
measured
chemical
property
and
fate
data
are
used.
Modeling
inputs
for
fate
and
transport
of
the
linear
alkyl
benzenesulfonates
were
assumed
to
be
stable.
This
approach
is
expected
to
be
conservative,
resulting
in
exposures
that
are
unlikely
to
actually
occur
in
the
environment
based
on
physicalchemical
inputs
and
environmental
fate
and
the
application
rate
used.
Compounds
modeled
as
stable
and
very
mobile,
result
in
exposures
that
will
be
linear
with
increases
in
application
rate
or
in
numbers
of
applications.
For
example,
the
exposures
from
a
2
pound
application
rate
will
be
twice
as
high
from
a
1
pound
application
rate,
whether
applied
at
once
or
separated
by
time
within
a
year.
Environmental
fate
data
and
default
application
rate
information
are
presented
in
Table
1.
The
results
of
the
model
were
then
scaled
to
adjust
for
an
effective
application
rate
of
0.1
lbs/
acre
(
based
upon
a
linear
alkyl
benzenesulfonate
weight
fraction
of
5%
(
a
>
95th
percentile
value),
a
product
application
rate
of
1
lb/
product
acre
and
four
applications
per
year).

Table
1.
Linear
Alkyl
Benzenesulfonate
Modeling
Input
Parameters
for
FIRST
and
GENEEC
Parameter
Value
Source
Maximum
single
application
rate
(
lb/
acre)
1
Assumed.

Application
Method
Aerial
Spray
No
limits
on
application
method;
method
yielding
most
conservative
results
used
Max
No.
application
per
year
4
Assumed
PCA
factor
(
decimal)
0.87
(
default)
Effland
et
al
(
2000)

Kd
(
mL/
g)
0.01
Assumed
Page
11
of
12
Aerobic
soil
met.
t1/
2
(
d)
Stable
1
Assumed
Solubility
(
mg/
L)
100000
assumed
Aerobic
aquatic
met.
t1/
2
(
d)
Stable
1
assumed
Hydrolysis
(
pH
7)
t1/
2
(
d)
Stable
1
assumed
Aqueous
photolysis
t1/
2
(
d)
Stable
1
assumed
1
For
the
purpose
of
estimating
a
high­
end
surface
water
concentration,
linear
alkyl
benzenesulfonates
are
assumed
to
be
stable
to
these
degradation
pathways
on
the
field
and
in
surface
water.

Drinking
Water
EEC
Using
FIRST:

RUN
No.
1
FOR
Generic
ON
Generic
*
INPUT
VALUES
*
____________________________________________________________________
RATE
(#/
AC)
No.
APPS
&
SOIL
SOLUBIL
APPL
TYPE
%
CROPPED
INCORP
ONE(
MULT)
INTERVAL
Kd
(
PPM
)
(%
DRIFT)
AREA
(
IN)
____________________________________________________________________
1.000(
1.000)
1
1
.0*******
AERIAL(
16.0)
87.0
.0
FIELD
AND
RESERVOIR
HALFLIFE
VALUES
(
DAYS)
____________________________________________________________________
METABOLIC
DAYS
UNTIL
HYDROLYSIS
PHOTOLYSIS
METABOLIC
COMBINED
(
FIELD)
RAIN/
RUNOFF
(
RESERVOIR)
(
RES._
EFF)
(
RESER.)
(
RESER.)
____________________________________________________________________
1000.00
2
N/
A
.00_
.00
.00
.00
UNTREATED
WATER
CONC
(
MICROGRAMS/
LITER
(
PPB))
Ver
1.0
AUG
1,
2001
____________________________________________________________________
PEAK
DAY
(
ACUTE)
ANNUAL
AVERAGE
(
CHRONIC)
CONCENTRATION
CONCENTRATION
____________________________________________________________________
92.170
66.089
ADJUSTED
UNTREATED
WATER
CONC
(
MICROGRAMS/
LITER
(
PPB))

____________________________________________________________________
PEAK
DAY
(
ACUTE)
ANNUAL
AVERAGE
(
CHRONIC)
CONCENTRATION
CONCENTRATION
____________________________________________________________________
9.217
6.609
Page
12
of
12
.
III.
Uncertainties
The
FIRST
model
is
designed
to
yield
concentration
values
which
exceed
those
predicted
by
the
linked
EPA
PRZM
and
EXAMS
models
for
all
but
the
most
vulnerable
sites,
application
patterns
and
environmental
fate
properties.
PRZM/
EXAMS
predictions
may
exceed
FIRST
predictions
under
the
following
circumstances:

Applications
to
crops
in
managed
environments
known
to
produce
excessive
runoff
(
e.
g.,
crops
grown
over
plastic
mulch).

Applications
at
sites
with
hydrologic
group
D
soils
which
also
receive
excessively
high
rainfall
(
e.
g.,
EFED
sweet
potato
scenario
in
southern
Louisiana).

Multiple
applications
over
a
window
of
30
days
or
longer
in
exceptionally
high
rainfall
areas
(
e.
g.,
far
southeastern
US).

Linear
alkyl
benzenesulfonates
were
assumed
to
be
stable
in
surface
water
environments
which
likely
overestimate
actual
concentrations
given
the
available
information
related
to
the
ready
biodegradability
of
linear
alkylbenzensulfonates.