UNITED
STATES
ENVIRONMENTAL
PROTECTION
AGENCY
WASHINGTON
D.
C.,
20460
OFFICE
OF
PREVENTION,
PESTICIDES
AND
TOXIC
SUBSTANCES
PC
Code:
031301
DP
Barcodes:
D294452
Date:
24
January
2006
MEMORANDUM
SUBJECT:
DCNA
(
Dicloran):
Revised
Tier
I
Drinking
Water
EDWC's
for
Use
in
the
Human
Health
Risk
Assessment.

TO:
Christine
Olinger,
Chemist
RRBI/
HED
(
7509C)

FROM:
Cheryl
A.
Sutton,
Ph.
D.,
Environmental
Scientist
Environmental
Risk
Branch
IV
Environmental
Fate
and
Effects
Division
(
7507C)

APPROVED
BY:
Elizabeth
Behl,
Branch
Chief
ERB
IV/
EFED
(
7507C)

This
memo
summarizes
the
revised
Tier
I
estimated
drinking
water
concentrations
(
EDWC)
for
DCNA
in
surface
water
for
use
in
the
human
health
risk
assessment.
The
revision
is
due
to
the
submission
of
new
aerobic
aquatic
metabolism
data
by
the
registrant.
The
EDWC's
are
summarized
in
Table
1.
EFED
used
the
screening
model
FIRST
(
FQPA
Index
Reservoir
Screening
Tool)
to
calculate
the
surface
water
EDWC.
The
groundwater
EDWC
(
1.3
ug/
L
ppb)
reported
in
the
initial
DWA
has
not
changed.
Both
surface
water
(
acute
and
chronic)
and
groundwater
EDWC's
are
based
on
DCNA
use
on
apricots
at
4.0
lb
a.
i./
A/
application
applied
in
a
single
application.

Table
1.
Tier
I
surface
water
EDWCs
for
DCNA
for
the
drinking
water
assessment.

Surface
water
drinking
water
sources
1­
in­
10­
year
acute:
172.8
ug/
L
(
ppb)
1­
in­
10­
year
chronic:
1.8
ug/
L
(
ppb)

An
additional
degradate,
2,6­
dicholorbenzoic
acid
(
DCBA),
was
identified
in
the
newly
submitted
aerobic
aquatic
metabolism
study
at
maximum
concentrations
of
9.2­
9.3%
of
the
applied
in
the
water
phase
(
7
days)
and
3.3­
5.8%
of
the
applied
in
the
sediment
phase
(
14
days).
By
study
termination,
DCBA
had
decreased
to
1.0­
1.7%
of
the
applied
in
the
water
phase.
There
were
no
major
degradates
of
DCNA
detected
in
the
previously
reviewed
laboratory
studies
(
i.
e.
none
accounted
for
as
much
as
10%
of
radioactivity
measured
at
any
point
in
the
studies),
with
the
exception
of
the
transformed
chemical
present
as
nonextractable
residues.
The
minor
degradates
of
DCNA
expected
in
the
environment
are:
2,6­
dichloro­
pphenylenediamine
(
DCPD);
4­
amino­
3,5­
dichloroacetanilide
(
DCAA);
and
2,6­
dichloro­
4­
hydroxyaniline
(
DCHA);
and
3,5­
dichloro­
4­
hydroxyacetanilide
(
3,5HA).

Estimated
Drinking
Water
Concentrations
2
To
estimate
the
surface
water
concentrations,
the
application
rates
for
apricots
(
a
single
application
of
4.0
lb
a.
i./
A/
application)
was
used,
which
represents
the
maximum
label
rate
across
all
crops.
While
there
are
several
different
types
of
applications
to
apricots
listed
on
the
labels
at
that
rate,
an
aerial
application
was
modeled,
as
it
yields
the
highest
EDWC's
due
to
the
higher
levels
of
spray
drift
associated
with
that
application
type.
Because
the
Tier
I
model
is
not
dependent
on
crop
type
(
other
than
for
a
percentage
crop
area
factor),
the
EDWC's
determined
for
apricots
are
also
applicable
to
other
crops
receiving
4
lb
a.
i./
A
by
aerial
application.

A
summary
of
the
model
input
parameter
values
used
in
FIRST
is
presented
in
Table
2.
The
FIRST
output
file
is
located
in
Attachment
1.
The
modeling
input
value
for
the
aerobic
aquatic
metabolism
half­
life
was
decreased
to
3.7
days
from
the
initially
used
value
of
1828
days
based
on
the
newly
submitted
data.
A
table
of
the
source
data
used
to
determine
input
parameter
values
is
located
in
Attachment
2.

FIRST
(
v1.0)
is
a
screening­
level
model
designed
to
estimate
the
pesticide
concentrations
found
in
surface
water
for
use
in
drinking
water
assessments.
The
model
provides
upper
bound
estimates
of
environmental
concentrations
(
acute
and
chronic)
in
surface
water
drinking
water
sources
(
untreated)
that
might
occur
following
the
use
of
a
pesticide.
FIRST
uses
basic
environmental
fate
data
and
pesticide
label
use
and
application
information
to
estimate
the
EDWCs
following
the
treatment
of
a
10­
hectare
field
with
subsequent
runoff
into
a
reservoir
(
an
Index
Reservoir,
based
on
Shipman
City
Lake
in
Illinois,
a
13­
acre
lake
9­
feet
deep
with
a
watershed
area
of
427
acres
or
172.8
hectares)
that
undergoes
two
full
turnovers
annually.
FIRST
also
uses
a
Percent
Cropped
Area
(
PCA)
factor
to
adjust
for
the
area
within
the
watershed
that
is
planted
to
the
modeled
crop.
In
the
model,
a
single
runoff
event
occurs
two
days
after
the
last
application
and
can
move
a
maximum
of
8%
of
the
applied
pesticide
into
the
reservoir,
with
the
amount
dependent
on
the
degradation
and
adsorption
of
the
pesticide
which
occurs
in
the
field
prior
to
the
event,
any
incorporation
of
the
pesticide
at
the
time
of
application,
and
the
PCA.
The
model
also
accounts
for
degradation
and
binding
to
sediment
which
may
occur
in
the
reservoir
following
the
runoff
event.
Spray
drift
(
resulting
in
direct
deposition
of
the
pesticide
into
the
reservoir
or
indirect
loading
from
spray
drift
landing
on
the
feeding
stream)
in
the
model
is
equivalent
to
16%
of
the
applied
for
aerial
application,
6.3%
for
orchard
air
blast
application,
and
6.4%
for
other
ground
spray
application.

For
use
in
the
human
health
risk
assessment,
EFED
recommends
a
revised
1­
in­
10­
year
acute
surface
water
EDWC
of
172.8
ppb
(
decreased
from
182
ppb)
and
a
revised
1­
in­
10­
year
chronic
EDWC
of
1.8
ppb
(
decreased
from
35
ppb),
both
based
on
the
use
of
DCNA
on
apricots
at
a
rate
of
a
single
application
of
4
lb
a.
i./
A.
The
recommended
EWDC
for
groundwater,
also
based
on
the
use
of
apricots
at
the
previously
stated
rate,
remains
at
1.3
ppb.
3
Table
2.
FIRST
(
v1.0)
input
parameter
values
for
DCNA
applied
to
apricots
by
aerial
application.

Parameter
Value
Source/
Comments
Application
Rate
(
lb
a.
i./
A)
4
EPA
Reg.
No.
10163­
188
Number
of
Applications
1
EPA
Reg.
No.
10163­
188
Interval
between
Applications
(
days)
Not
Applicable
 

Organic
Carbon
Partitioning
Coefficient
(
Koc;
mL/
g)
660
MRID
40538202;
lowest
non­
sand
value
of
four
values,
per
input
parameter
guidance
Aerobic
Soil
Metabolism
Half­
life
(
days)
914
MRID
40894801;
input
value
represents
the
90th
percentile
of
the
upper
confidence
bound
on
the
average
of
two
half­
life
values,
per
input
parameter
guidance
Wetted
in?
No
Input
parameter
guidance
Depth
of
Incorporation
(
inches)
0
Input
parameter
guidance
Method
of
Application
aerial
spray
EPA
Reg.
No.
10163­
188
Percent
Cropped
Area
0.87
(
default
value)
Input
parameter
guidance
Solubility
in
Water
(
mg/
L
or
ppm)
7
@
20
oC
Product
chemistry
data
Aerobic
Aquatic
Metabolism
Half­
life
(
days)
3.7
MRID
46657101;
input
value
represents
the
90th
percentile
of
the
upper
confidence
bound
on
the
average
of
two
half­
life
values,
per
input
parameter
guidance
Hydrolysis
Half­
life
@
pH
7
(
days)
stable
ACC
No.
253963
Aquatic
Photolysis
Half­
life
@
pH7
(
days)
1.97
MRID's
43891901,
45575001
4
ATTACHMENT
1:
FIRST
File
RUN
No.
1
FOR
dcna
ON
apricotr
*
INPUT
VALUES
*
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
RATE
(#/
AC)
No.
APPS
&
SOIL
SOLUBIL
APPL
TYPE
%
CROPPED
INCORP
ONE(
MULT)
INTERVAL
Koc
(
PPM
)
(%
DRIFT)
AREA
(
IN)
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
4.000(
4.000)
1
1
660.0
7.0
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.)
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
914.00
2
N/
A
1.97­
244.28
3.70
3.64
UNTREATED
WATER
CONC
(
MICROGRAMS/
LITER
(
PPB))
Ver
1.0
AUG
1,
2001
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
PEAK
DAY
(
ACUTE)
ANNUAL
AVERAGE
(
CHRONIC)
CONCENTRATION
CONCENTRATION
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
172.801
1.839
5
ATTACHMENT
2:
General
fate
and
physical­
chemical
property
source
data
used
for
DCNA
aquatic
exposure
modeling.

PARAMETER
VALUE
SOURCE
OF
INFO./
COMMENTS
Chemical
Name
2,6­
dichloro­
4­
nitroaniline
(
IUPAC)
2,6­
dichloro­
4­
nitrobenzenamine
(
CAS)
 

Molecular
Weight
207.06
g/
mole
­­

Solubility
(
20
oC)
7
mg/
L
(
ppm)
@
20
oC
Registrant
Dissociation
Constant
(
pKa)
3.31
Registrant
Vapor
Pressure
1.96
x
10­
6
mmHg
@
25
oC
1.2
x
10­
6
mmHg
@
20
oC
Registrant
Hydrolysis
Half­
life
(
pH
5,
7,
9;
25
oC)
stable
at
pH
5,
7,
9
Accession
No.
253963
Aqueous
Photolysis
Half­
life
(
pH
7)
47.2
hours
(
1.97
days)
MRID's
43891901,
45575001
Soil
Photolysis
Half­
life
263.2
hours
MRID
43893601
Aerobic
Soil
Metabolism
Half­
life
18
months
(
approx.
540
days)
in
sandy
loam
soil,
6
months
(
approx.
180
days)
in
sand
soil
MRID
40894801
Anaerobic
Soil
Metabolism
Half­
life
38
days
in
sandy
loam
soil,
24
days
in
sand
soil
MRID
40894801
Anaerobic
Aquatic
Metabolism
Half­
life
0.45
days1
MRID
43866501
Aerobic
Aquatic
Metabolism
Half­
life
3.4,
3.5
days
MRID
46657101
Organic
Carbon
Partition
Coefficient
(
Koc)
660,
735,
760,
1062
MRID
40538202
Soil
Partition
Coefficient
(
Kd,
mL/
g)
3.7,
9.7,
13.6,
15.4
mL/
g
MRID
40538202
Log
Kow
2.76
MRID
41176202
Henry's
Law
Constant
(
atm*
m3/
mol)
7.78
x
10­
8
Registrant
Bioconcentration
Factors
(
BCF)
in
Fish
136X
whole
fish
tissue
49X
edible
tissue
264X
nonedible
tissue
MRID
43782001
1The
half­
life
was
determined
in
a
high
organic
matter
(
13.4%)
sediment
which
may
not
be
respresentative
of
the
soils
on
which
DCNA
will
be
used.
In
sandy
loam
(
3.1%
o.
m.)
and
sand
(
1.6%
o.
m.)
soils
treated
and
flooded
simultaneously,
and
then
anaerobically
incubated
as
part
of
another
study
(
MRID
40894801),
respective
anaerobic
aquatic
metabolism
half­
lives
of
10.1
and
5.6
days
were
determined.
In
an
aged
soil
column
leaching
study
(
MRID
43809001)
where
the
soil
was
treated
and
aged
anaerobically
prior
to
placement
on
the
columns,
the
half­
lives
of
DCNA
in
sandy
loam
(
2.8%
o.
m.),
sand
(
0.59%
o.
m.),
silt
loam
(
0.54%
o.
m.)
and
clay
(
1.41%
o.
m.)
soils,
respectively,
were
0.8,
8.5,
9.2
and
5.9
days.
