Document ID: EPA-HQ-OPP-2006-0339-0007
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2006-04-26T04:00Z

UNITED
STATES
ENVIRONMENTAL
PROTECTION
AGENCY
WASHINGTON
D.
C.,
20460
OFFICE
OF
PREVENTIN,
PESTICIDES
AND
TOXIC
SUBSTANCES
PC
Code:
069105,
069149
DP
Barcodes:
325482,
325483
Date:
January
23,
2006
MEMORANDUM
SUBJECT:
Tier
I
Drinking
Water
Assessment
for
alkyl*
dimethyl
benzyl
ammonium
chloride
*(
50%
C14,
40%
C12,
10%
C16)
(
ADBAC)
and
didecyl
dimethyl
ammonium
chloride
(
DDAC)

TO:
Jacqueline
McFarland,
Chemical
Review
Manager
Regulatory
Management
Branch
I
Antimicrobials
Division
(
7510C)

Tracy
Lantz,
Chemical
Review
Manager
Regulatory
Management
Branch
I
Antimicrobials
Division
(
7510C)

Matthew
Lloyd,
Risk
Assessor
Re­
Registration
Branch
I
Health
Effects
Division
FROM:
Marietta
Echeverria,
Environmental
Scientist
Environmental
Risk
Branch
IV
Environmental
Fate
and
Effects
Division
THROUGH:
R.
David
Jones,
PhD,
Senior
Agronomist
Environmental
Risk
Branch
IV
Environmental
Fate
and
Effects
Division
APPROVED
BY:
Elizabeth
Behl,
Branch
Chief
Environmental
Risk
Branch
IV
Environmental
Fate
and
Effects
Division
Attached
is
the
drinking
water
exposure
assessment
for
the
agricultural
uses
ADBAC
and
DDAC
for
the
re­
registration
eligibility
decision.
If
additional
refinements
are
necessary,
please
contact
Marietta
Echeverria
at
703­
305­
8578
or
echeverria.
marietta@
epa.
gov.
Page
2
of
11
Tier
I
Drinking
Water
Exposure
Assessment
for
the
Outdoor
Uses
for
the
Re­
registration
of
ADBAC
and
DDAC
Alkyl*
dimethyl
benzyl
ammonium
chloride
*(
50%
C14,
40%
C12,
10%
C16)
(
ADBAC)
CAS
No.
68424­
85­
1;
Didecyl
dimethyl
ammonium
chloride
(
DDAC)
CAS
No.
7173­
51­
5
Prepared
by:

Marietta
Echeverria,
Environmental
Scientist
Environmental
Risk
Branch
IV
Reviewed
by:
R.
David
Jones,
PhD,
Senior
Agronomist
Elizabeth
Behl,
Branch
Chief
Environmental
Risk
Branch
IV
Environmental
Fate
and
Effects
Division
U.
S.
Environmental
Protection
Agency
Office
of
Pesticide
Programs
Environmental
Fate
and
Effects
Division
Environmental
Risk
Branch
IV
1200
Pennsylvania
Ave.,
NW
Mail
Code
7507C
Washington,
DC
20460
Page
3
of
11
1
EXECUTIVE
SUMMARY
This
document
reports
the
drinking
water
exposure
assessment
for
ADBAC
and
DDAC
that
has
been
conducted
to
support
the
human
health
risk
assessment
for
the
reregistration
of
ADBAC
and
DDAC
outdoor
uses.
As
an
outdoor
pesticide,
ADBAC
is
used
on
nursery
ornamentals,
turf,
and
for
mosquito
control
in
ponds
and
puddles
and
as
an
algaecide
in
decorative
pools.
The
only
DDAC
outdoor
use
is
as
an
algaecide
in
decorative
pools.
For
the
mosquito
control
use
and
the
algaecide
use
on
decorative
pools,
the
labels
suggest
that
the
use
sites
(
water
bodies)
are
ornamental
and
periodic
in
nature
and
as
such
disconnected
from
the
larger
watershed.
Therefore,
for
the
purposes
of
this
assessment
these
uses
were
not
considered
potential
sources
of
drinking
water
exposure.
This
assessment
only
considered
the
labeled
turf
and
nursery
uses
for
ADBAC.
Foliar
spray,
drench
and
"
dribble"
applications
are
allowed.

Tier
1
surface
water
and
groundwater
modeling
was
conducted
for
the
labeled
nursery
ornamental
use
(
EPA
Reg.
No.
58044­
3,
53642­
1),
which
represents
the
highest
use
rate
of
all
labeled
uses
with
an
application
rate
of
302
lbs.
a.
i./
A
and
a
maximum
of
3
applications
per
year.
Since
the
tier
I
models
are
not
dependent
on
"
crop"
type,
the
EDWCs
determined
for
the
nursery
ornamental
use
are
also
protective
of
all
other
uses
with
lower
application
rates.
The
recommended
estimated
drinking
water
concentrations
(
EDWCs)
for
the
human
health
risk
assessment
are
in
Table
1
and
are
based
on
the
nursery
ornamental
use
pattern.
There
were
no
major
degradates
of
ADBAC
in
the
laboratory
studies.

Table
1.
Tier
I
Estimated
Drinking
Water
Concentrations
(
EDWCs)
based
on
aerial
application
of
ADBAC
on
nursery
ornamentals
Drinking
Water
Source
(
Model)
Use
rate
(
lbs
ai/
A/
year)
EDWC
(
ppb)

Surface
water
(
FIRST)

­
Acute
(
peak)

­
Chronic
(
annual
average)
906
13,129
331
Groundwater
(
SCIGROW)
906
5.4
2
PROBLEM
FORMULATION
This
is
a
Tier
I
drinking
water
assessment
that
uses
modeling
and
available
monitoring
data
to
estimate
the
groundwater
and
surface
water
concentrations
in
drinking
water
source
water
(
pre­
treatment)
resulting
from
pesticide
use
on
sites
that
are
highly
vulnerable.
This
initial
tier
screens
out
chemicals
with
low
potential
risk
and
allows
OPP
to
focus
resources
on
more
refined
risk
assessments
for
chemicals
which
potentially
present
more
significant
risks.
This
drinking
water
assessment
will
report
potential
exposure
concentrations
for
the
human
health
dietary
risk
Page
4
of
11
assessment
and
provide
a
clear
and
transparent
description
of
how
those
concentrations
were
determined.

3
ANALYSIS
3.1
Use
Characterization
ADBAC
and
DDAC
are
used
primarily
as
antimicrobial
agents;
evaluation
of
these
uses
can
be
found
in
the
AD
RED.
Additionally,
ADBAC
is
used
on
ornamental
plants
and
shrubs,
residential
lawns
and
commercial
turf
and
golf
course
greens,
tees
and
fairways.
Both
ADBAC
and
DDAC
are
labeled
for
use
in
puddles
and
decorative
pools
to
control
algae.
ADBAC
is
also
labeled
for
use
as
a
mosquito
larvicide
in
standing
waters,
including
decorative
ponds
and
pools,
inactive
spas
and
hot
tubs,
as
well
as
`
old
tires,
empty
tin
cans,
puddles
and
water
drains
around
buildings'
(
RD
20
label).
Only
the
ADBAC/
DDAC
uses
which
could
result
in
potential
environmental
exposures
to
drinking
water
sources
are
being
evaluated
in
this
assessment.
The
target
water
bodies
for
the
algaecide
and
the
mosquito
control
uses
were
assumed,
as
suggested
on
the
label,
ornamental
or
periodic
and
disconnected
from
the
larger
watershed.
Therefore,
there
were
no
DDAC
uses
considered
in
this
assessment.
The
remaining
ADBAC
uses
considered
in
this
assessment
are
described
below.

Turf
and
Golf
Courses
Two
ADBAC
products
are
labeled
for
use
on
residential
lawns,
commercial
turf
and
golf
courses,
Consan
and
RD
20.
These
uses
control
algal
build­
up,
and
fungal
diseases
such
as
fusarium
blight
(
Fusarium
spp.),
brown
patch
(
Rhizoctonia
spp.),
etc.
Smaller
use
sites,
such
as
residential
lawns,
are
labeled
for
a
rate
of
790
ppm,
one
gallon
of
solution
per
40
sq.
ft
of
lawn,
which
is
equivalent
to
6.8
lb
ai/
A.
This
rate
is
also
allowable
for
golf
courses
and
commercial
(
nonagricultural)
turf
unless
a
commercial
power
sprayer
is
used.
If
a
commercial
power
sprayer
is
used,
the
application
rate
is
reduced
to
512
ppm
(
1
pint
of
product
in
50
gallons
for
0.25
A),
a
rate
of
0.82
lb
ai/
A.
Presumably,
as
implied
on
the
labels,
smaller
areas
would
be
treated
at
the
higher
rate,
while
larger­
scale
applications
would
be
treated
at
the
lower
rate.

The
product
labels
do
not
specify
seasonal
or
yearly
limits
on
the
number
of
applications
or
pounds
per
acre.
The
label
does
specify
10­
14
days
between
applications.
The
label
states
applications
should
be
made
during
the
warm
growing
season,
so
the
number
of
applications
may
vary
depending
on
the
geographic
area
where
it
is
used.
Without
a
limit,
a
hypothetical
Florida
golf
course
could
apply
ADBAC
every
ten
days
all
year
long.
Without
data
indicating
otherwise,
this
seems
plausible
given
the
wide
range
of
target
organisms
for
which
ADBAC
controls
(
semi­
terrestrial
alga
species,
numerous
species
of
fungi).
However,
these
organisms
are
generally
only
a
big
problem
under
warm
wet
conditions,
so
some
use
sites
may
need
appreciably
fewer
applications
to
achieve
desired
control.

Nursery
Uses
(
bedding
plants,
ornamental
shrubs
and
trees)

The
products
Timsen,
Consan
and
RD
20
are
all
labeled
for
nursery
uses
for
the
control
of
various
fungal
and
bacterial
pathogens
that
can
cause
damage
to
ornamental
plants.
In
2002,
Page
5
of
11
there
were
68,214
acres
of
floriculture
(
bedding/
garden
plants,
cut
flowers
and
cut
florist
greens,
foliage
plants,
and
potted
flowering
plants)
grown
in
open
nurseries
in
the
US,
on
14,579
nurseries
(
www.
nass.
usda.
gov/
census/).
The
labels
allow
for
use
on
a
variety
of
herbaceous
annuals,
such
as
fuchsia
and
snapdragons,
as
well
as
larger
perennials
such
as
ash
and
sycamore
trees.
Because
different
ornamental
species
have
different
pathogen
pressures,
different
rates
are
recommended
for
each
pathogen
targeted.
For
instance,
palms
needing
protection
from
heart
rot
and
penicillium
leaf
base
rot
are
treated
with
Consan
at
a
concentration
of
1563
ppm
while
crepe
myrtle
and
fruit
trees
being
treated
for
fireblight
are
treated
at
a
concentration
of
781
ppm.
Differences
in
amount
of
product
that
will
potentially
be
available
for
exposure
to
drinking
water
sources
depends
on
the
quantity
of
solution
applied.
The
palm
treatment
uses
a
small
amount
of
solution
poured
into
the
`
cup'
formed
at
the
base
of
the
leaves,
repeated
weekly
until
control
is
achieved.
For
fireblight
control,
the
entire
tree
is
sprayed
at
two­
week
intervals,
with
some
phenological
limitations
(
e.
g.,
early
spring
and
fall
after
harvest;
Consan
label
only).
For
some
larger
ornamentals,
such
as
ash
or
sycamore,
the
label
states
that
50­
60
gallons
of
solution
(
528
ppm)
may
be
required
to
achieve
full
coverage.
These
applications
can
be
repeated
up
to
three
times,
at
intervals
determined
by
leaf
emergence
and
development.
These
treatments
are
equivalent
to
application
of
0.004
lbs
ai/
gallon/
treatment.
For
this
assessment,
the
maximum
60
gallons
was
assumed
to
be
required
per
tree
per
treatment
(
0.25
lbs
ai/
tree/
treatment).
It
was
also
assumed
that
the
trees
required
6'
x
6'
spacing.
Therefore,
based
on
these
assumptions
the
application
rate
used
in
this
assessment
was
302
lbs
ai/
A
(
0.25
lbs
ai/
tree/
treatment
x
1,210
trees/
A).

3.2
Environmental
Fate
and
Transport
Characterization
ADBAC
is
cationic
and
immobile
in
soil.
The
available
soil
mobility
study
shows
that
ADBAC
has
a
strong
tendency
to
bind
to
sediment/
soil
with
Freundlich
Kads
values
were
6,172
for
the
sand
soil,
10,797
for
the
silt
loam,
5,123
for
the
sandy
loam
soil,
and
32,429
for
the
clay
loam
(
MRID
424148­
01).
There
is
no
guideline
data
for
aerobic
soil
degradation
of
ADBAC.
Based
on
ADBAC's
vapor
pressure
(
3.5
x
10­
12
torr)
volatility
is
not
expected.
Because
of
its
strong
adsorption
to
soils,
the
potential
to
reach
aquatic
water
bodies
via
runoff
or
leaching
is
limited.
ADBAC
may,
however,
be
transported
off­
site
to
aquatic
water
bodies
as
entrained
sediment
or
via
spray
drift
during
aerial,
or
ground
spray
applications.
Once
in
aquatic
environments,
ADBAC
is
hydrolytically
stable
under
abiotic
and
buffered
conditions
over
the
pH
5­
9
range
(
MRID
408356­
02).
ADBAC
is
also
stable
to
photodegradation
in
pH
7
buffered
aqueous
solutions
(
MRID
408356­
03).

Aquatic
metabolism
studies
under
aerobic
and
anaerobic
conditions
indicate
that
ADBAC
is
stable
to
microbial
degradation.
ADBAC
did
not
degrade
in
flooded
sand
loam
soil
that
was
incubated
at
24­
27
°
C
in
the
dark
for
up
to
30
days
in
an
aerobic
aquatic
metabolism
study
(
MRID
408356­
04).
Under
anaerobic
conditions,
ADBAC
was
found
to
be
very
resistant
to
degradation
with
a
calculated
half­
life
of
1,815
days
(
MRID
424151­
01).
However,
a
report
on
the
biodegradability
of
ADBAC
prepared
by
the
Registrant
concluded
that
the
degree
of
ADBAC
biodegradability
is
variable
and
is
influenced
by
the
chemical
concentration,
alkyl
chain
length,
the
presence
of
anionic
moieties
and
the
quantity
and
characteristics
of
the
microbial
Page
6
of
11
population.
This
report
was
based
on
information
from
the
open
literature,
unpublished
sources,
and
meeting
proceedings
and
has
not
been
reviewed
by
the
Agency.

Major
degradates
were
not
identified
in
any
of
the
available
studies.
The
environmental
fate
and
physical­
chemical
properties,
based
on
submitted
guideline
studies,
are
summarized
in
Table
3.1.
Details
of
individual
studies
can
be
found
in
the
ADBAC
Environmental
Fate
Assessment
conducted
by
the
AD.

Table
3.1
General
fate
and
physical­
chemical
data
for
ADBAC.
Parameter
Value
Source
Molecular
Weight
377.83
Product
chemistry
Solubility
(
25
º
C)
Completely
sol.
Product
chemistry
Vapor
Pressure
(
25
º
C)
3.53
x
10­
12
Product
chemistry
Hydrolysis
Half­
life
(
25
º
C)
pH
5
pH
7
pH
9
150
d
183
d
379
d
MRID408356­
02,
424152­
01
Aqueous
Photolysis
Half­
life
stable
MRIDs
408356­
03,
424152­
01
Soil
Photolysis
Half­
life
no
data
Aerobic
Soil
Metabolism
Half­
life
no
data
Aerobic
Aquatic
Metabolism
Half­
life
stable
(
sand
loam)
MRIDs
408356­
04,
424149­
01
Anaerobic
Aquatic
Metabolism
Half­
life
1,815
d
(
sandy
loam)
MRIDs
411055­
01,
424150­
02
Organic
Carbon
Partitioning
Coefficient
(
Koc,
L/
kgoc)
6.2
x
106,
2.2
x
106,
6.4
x
105,
1.7
x
106
MRID
408356­
05
Soil
Partitioning
Coefficient
(
kd,
L/
kg)
6,172,
10,797,
5,123,
32,429
MRID
408356­
05
3.3
Drinking
Water
Exposure
Modeling
Tier
1
modeling
was
used
to
estimate
the
drinking
water
exposure
for
use
in
the
dietary
risk
assessment
of
ADBAC/
DDAC.
Following
is
a
description
of
the
models
used,
the
selection
of
the
model
input
parameters
and
a
characterization
of
the
output
from
these
simulations.

3.3.1
Models
Tier
1
EDWCs
for
surface
water
were
generated
using
FIRST,
dated
August
5,
2001.
FIRST
is
a
screening
model
designed
by
the
Environmental
Fate
and
Effects
Division
(
EFED,
2001a)
of
the
Office
of
Pesticide
Programs
to
estimate
the
concentrations
found
in
drinking
water
from
surface
water
sources
for
use
in
human
health
risk
assessment.
As
such,
it
provides
upper
bound
values
on
the
concentrations
that
might
be
found
in
drinking
water
due
to
the
use
of
a
pesticide.
FIRST
is
a
single
event
model
(
one
runoff
event),
but
can
account
for
spray
drift
from
multiple
applications.
Spray
drift
(
resulting
in
direct
deposition
of
the
pesticide
into
the
reservoir)
is
assumed
to
be
16%
of
the
applied
active
ingredient
for
aerial
application,
6.3%
for
orchard
air
blast
application,
and
6.4%
for
other
ground
spray
application.
FIRST
is
hardwired
to
represent
the
Index
Reservoir,
a
standard
water
body
used
by
the
Office
of
Pesticide
Programs
to
assess
drinking
water
exposure
(
Office
of
Pesticide
Programs,
2002).
It
is
based
on
a
real
reservoir,
Shipman
City
Lake
in
Illinois,
that
is
known
to
be
vulnerable
to
pesticide
contamination.
The
single
runoff
event
moves
a
maximum
of
8%
of
the
applied
pesticide
into
the
Page
7
of
11
reservoir.
This
amount
can
be
reduced
due
to
degradation
on
the
field
and
the
effects
of
binding
to
soil
in
the
field.
FIRST
also
uses
a
Percent
Cropped
Area
(
PCA)
factor
to
adjust
for
the
area
within
the
watershed
that
is
planted
to
the
modeled
crop.
No
PCA
was
used
in
this
assessment
since
there
are
no
standard
PCAs
for
non­
agricultural
crops
such
as
nursery
ornamentals.

Tier
1
EDWCs
for
groundwater
were
generated
with
SCIGROW
2.3,
dated
July
29,
2003
(
EFED,
2001b).
SCIGROW
is
a
regression
model
used
as
a
screening
tool
for
ground
water
used
as
drinking
water.
SCIGROW
was
developed
by
regressing
the
results
of
Prospective
Ground
Water
studies
against
the
Relative
Index
of
Leaching
Potential
(
RILP).
The
RILP
is
function
of
aerobic
soil
metabolism
and
the
soil­
water
partition
coefficient.
The
output
of
SCIGROW
represents
the
concentrations
that
might
be
expected
in
shallow
unconfined
aquifers
under
sandy
soils.

3.3.2
Modeling
Approach
and
Input
Parameters
A
summary
of
the
model
input
parameter
values
used
in
FIRST
and
SCIGROW
are
presented
in
Tables
3.2
and
3.3,
respectively.
These
parameters
were
selected
in
accordance
with
EFED's
input
parameter
guidance
(
Environmental
Fate
and
Effects
Division,
2002).

For
the
surface
water
and
groundwater
assessments,
the
application
rates
for
ornamental
trees
(
302
lb
a.
i./
A/
application)
was
used,
which
represents
the
maximum
label
rate
across
all
uses.
This
rate
assumes
a
tree
spacing
of
6'
x
6'
and
a
maximum
application
of
60
gallons
per
tree
(
i.
e.,
0.25
lbs
ai/
tree/
application
and
1,210
trees/
A).
Because
the
Tier
I
models
are
not
dependent
on
crop
type,
the
EDWCs
determined
for
ornamentals
are
also
protective
of
all
other
uses
with
lower
application
rates
(
turf;
golf
courses).

Based
on
registrant­
submitted
data
for
ADBAC,
aqueous
photolysis,
aerobic
soil
metabolism
and
aerobic
aquatic
metabolism
were
assumed
stable
for
surface
water
modeling
with
FIRST.
The
soil
partitioning
coefficient
used
in
FIRST
was
5,123
L/
kg,
the
lowest
nonsand
Kd
of
four
values
and
hydrolysis
half­
life
was
183
d.
For
groundwater
modeling
with
SCIGROW,
aerobic
soil
metabolism
was
also
assumed
stable
and
the
median
organic
carbon
partitioning
coefficient,
1.95
x
106
L/
kgoc,
was
used.
This
value
for
Koc
is
well
outside
the
range
for
which
SCIGROW
was
developed.

Table
3.2
FIRST
(
v
1.0)
input
parameter
values
for
ADBAC
applied
to
ornamentals
by
aerial
application.

Parameter
Value
Source
Comments
Application
Rate
(
lb
a.
i./
A)
302
EPA
Reg.
No.
58044­
3
Application
rate
for
ornamentals
Number
of
Applications
3
EPA
Reg.
No.
58044­
3
Interval
between
Applications
(
days)
7
EPA
Reg.
No.
58044­
3
Soil
Partitioning
Coefficient
(
Koc;
L/
kgoc)
6.4
x
105
MRID
408356­
05,421489­
01
lowest
non­
sand
value
of
four
values
Page
8
of
11
Table
3.2
FIRST
(
v
1.0)
input
parameter
values
for
ADBAC
applied
to
ornamentals
by
aerial
application.

Parameter
Value
Source
Comments
Aerobic
Soil
Metabolism
Halflife
(
days)
0
no
data
stable
to
aerobic
soil
metabolism
Wetted
in?
No
Aerially
applied
Depth
of
Incorporation
(
inches)
0
Aerially
applied
Method
of
Application
aerial
spray
EPA
Reg.
No.
58044­
3
Percent
Cropped
Area
(
fraction)
1
Default
No
PCA
for
nursery
ornamentals
Solubility
in
Water
(
mg/
L)
18.4
Product
chemistry
Aerobic
Aquatic
Metabolism
Half­
life
(
days)
0
MRIDs
408356­
04,
424149­
01
stable
to
aerobic
aquatic
metabolism
Hydrolysis
Half­
life
(
days)
183
MRID
408356­
05,
424152­
01
Aquatic
Photolysis
Half­
life
(
days)
0
MRIDs
46438203,
42419001
stable
to
aquatic
photolysis
Table
3.3
SCIGROW
2.3
input
parameter
values
for
ADBAC
applied
to
ornamentals.

Parameter
Value
Source
Comments
Maximum
Application
Rate
(
lb
a.
i./
A/
application)
302
EPA
Reg.
No.
58044­
3
Maximum
Number
of
Applications
per
Year
3
EPA
Reg.
No.
58044­
3
Aerobic
Soil
Metabolism
Half­
life
(
days)
10,000
no
data
stable
to
aerobic
soil
metabolism
Organic
Carbon
Partition
Coefficient
(
Koc,
L/
kgoc)
1.95
x
106
MRID
408356­
05,421489­
01
median
koc
3.3.3
Modeling
Results
The
FIRST
and
SCI­
GROW
output
files
are
located
in
Appendix
A.

For
use
in
the
human
health
risk
assessment,
EFED
recommends
an
acute
(
peak)
surface
water
EDWC
of
13,129
µ
g/
L
and
a
chronic
(
annual
mean)
EDWC
of
331
µ
g/
L,
both
based
on
the
use
of
ADBAC
on
ornamentals
at
a
annual
application
rate
of
906
lb
a.
i./
A/
year.
The
recommended
EWDC
for
groundwater,
also
based
on
the
use
of
ornamentals
at
the
previously
stated
rate,
is
5.4
µ
g/
L.
Because
of
ADBAC's
relative
persistence
there
is
a
potential
for
accumulation
in
water
bodies
with
long
residence
times.
Page
9
of
11
3.4
Monitoring
Data
There
were
no
national­
scale
monitoring
data
available
for
this
assessment.

3.5
Drinking
Water
Treatment
There
is
no
available
information
on
treatment
effects
on
ADBAC
in
drinking
water.
ADBAC's
high
sorption
potential
suggests
that
treatment
by
flocculation/
sedimentation
and
activated
carbon
could
result
in
decreased
residues
of
ADBAC
in
treated
drinking
water.

4
CONCLUSIONS
For
groundwater,
the
empirical
model,
SCIGROW,
was
used.
SCIGROW
is
based
on
13
prospective
groundwater
studies
performed
in
areas
of
high
leaching
potential
with
chemicals
with
low
Koc.
Because
the
Koc
of
ADBAC
is
well
outside
the
range
of
SCIGROW,
the
model
simply
returns
a
default
value
concentration
(
5.4
µ
g/
L).
For
compounds
with
Koc
values
over
10,000
ml/
g,
SCIGROW
assumes
0.006
µ
g/
L
for
every
pound
per
acre
applied.
Because
of
ADBAC's
high
partitioning
coefficient,
relative
non­
persistence
in
aerobic
soils,
and
demonstrated
fate
and
transport
in
the
field,
leaching
to
groundwater
is
not
expected
to
be
a
major
route
of
dissipation.

The
estimated
concentrations
provided
in
this
assessment
for
are
conservative
estimates
of
ADBAC
concentrations
in
drinking
water.
Major
sources
of
uncertainty
include
the
assumptions
used
in
deriving
the
application
rate
and
the
appropriate
percent
cropped
area
for
nursery
ornamentals.
The
application
rate
was
derived
from
the
label­
prescribed
maximum
concentrations
used
for
treatments,
the
maximum
volumes
of
product
required
for
treatments,
and
an
assumed
tree
spacing
of
6'
x
6'.
Since
there
is
no
standard
PCA
for
nurseries,
this
assessment
is
based
on
the
assumption
that
an
entire
178­
ha
watershed
consists
of
nursery
ornamentals
(
spaced
6'
x
6')
all
of
which
are
treated
simultaneously
with
ADBAC.
This
is
unlikely.

If
dietary
risks
require
refinement,
higher
tiered
crop­
specific
and
location­
specific
models
and
modeling
scenarios
can
be
utilized
upon
request.
Page
10
of
11
Appendix
A:
Input/
Output
Modeling
Files
FIRST
File
RUN
No.
1
FOR
ADBAC
ON
ornamental
*
INPUT
VALUES
*
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
RATE
(#/
AC)
No.
APPS
&
SOIL
SOLUBIL
APPL
TYPE
%
CROPPED
INCORP
ONE(
MULT)
INTERVAL
Kd
(
PPM
)
(%
DRIFT)
AREA
(
IN)
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
302.000(
906.000)
3
7
5123.0
18.4
AERIAL(
16.0)
100.0
.0
FIELD
AND
RESERVOIR
HALFLIFE
VALUES
(
DAYS)
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
METABOLIC
DAYS
UNTIL
HYDROLYSIS
PHOTOLYSIS
METABOLIC
COMBINED
(
FIELD)
RAIN/
RUNOFF
(
RESERVOIR)
(
RES.­
EFF)
(
RESER.)
(
RESER.)
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
.00
2
183.00
.00­
.00
.00
183.00
UNTREATED
WATER
CONC
(
MILLIGRAMS/
LITER
(
PPM))
Ver
1.0
AUG
1,
2001
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
PEAK
DAY
(
ACUTE)
ANNUAL
AVERAGE
(
CHRONIC)
CONCENTRATION
CONCENTRATION
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
13.129
.331
SCIGROW
File
SCIGROW
VERSION
2.3
ENVIRONMENTAL
FATE
AND
EFFECTS
DIVISION
OFFICE
OF
PESTICIDE
PROGRAMS
U.
S.
ENVIRONMENTAL
PROTECTION
AGENCY
SCREENING
MODEL
FOR
AQUATIC
PESTICIDE
EXPOSURE
SciGrow
version
2.3
chemical:
SDBAC
time
is
1/
25/
2006
9:
28:
7
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
Application
Number
of
Total
Use
Koc
Soil
Aerobic
rate
(
lb/
acre)
applications
(
lb/
acre/
yr)
(
ml/
g)
metabolism
(
days)
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
302.000
3.0
906.000
6.40E+
05
10000.0
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
groundwater
screening
cond
(
ppb)
=
5.44E+
00*
*
Estimated
concentrations
of
chemicals
with
Koc
values
greater
than
9995
ml/
g
are
beyond
the
scope
of
the
regression
data
used
in
SCI­
GROW
development.
If
there
are
concerns
for
such
chemicals,
a
higher
tier
groundwater
exposure
assessment
should
be
considered,
regardless
of
the
concentration
returned
by
SCI­
GROW.
************************************************************************
Page
11
of
11
References
Environmental
Fate
and
Effects
Division.
2001a.
FIRST
(
F)
IFRA
(
I)
ndex
(
R)
eservoir
(
S)
creening
(
T)
ool.
Tier
1
Model
for
Drinking
Water
Exposure:
User's
Manual.
http://
www.
epa.
gov/
oppefed1/
models/
water/
first_
users_
manual.
htm
Environmental
Fate
and
Effects
Division.
2001b.
SCI­
GROW
­
(
S)
creening
(
C)
oncentration
(
I)
n
(
GRO)
und
(
W)
ater:
User's
Manual.
http://
www.
epa.
gov/
oppefed1/
models/
water/
scigrow_
users_
manual.
htm
Environmental
Fate
and
Effects
Division.
2002.
Guidance
for
Selecting
Input
Parameters
in
Modeling
the
Environmental
Fate
and
Transport
of
Pesticides,
Version
II.
U.
S.
Environmental
Protection
Agency.
Washington,
D.
C.
http://
www.
epa.
gov/
oppefed1/
models
water/
input_
guidance2_
28_
02.
htm/

Office
of
Pesticide
Programs.
2000.
Part
A.
Guidance
for
Use
of
the
Index
Reservoir
in
Drinking
Water
Assessments.
http://
www.
epa.
gov/
oppfead1/
trac/
science/
reservoir.
pdf