UNITED
STATES
ENVIRONMENTAL
PROTECTION
AGENCY
WASHINGTON,
D.
C.
20460
OFFICE
OF
PREVENTION,
PESTICIDES
AND
TOXIC
SUBSTANCES
Date:
July
14,
2006
Chemical:
Propiconazole
PC
Code:
122101
MEMORANDUM
SUBJECT:
Terrestrial
Plant
Runoff
Risk
Assessment
for
Propiconazole
on
Turf
Using
PRZM
FROM:
Kevin
Costello,
Acting
Team
Leader,
RB3
Special
Review
and
Reregistration
Division
THROUGH:
Michael
Goodis,
Branch
Chief,
RB3
Special
Review
and
Reregistration
Division
TO:
James
Lin,
Environmental
Engineer
James
Hetrick,
Senior
Scientist
Environmental
Risk
Branch
1
Environmental
Fate
and
Effects
Divsion
The
screening­
level
terrestrial
plant
risk
assessment
for
propiconazole
suggests
the
potential
for
a
risk
of
adverse
effects
on
seedling­
emergence
from
runoff
and
drift
to
adjacent
fields.
The
RQs
for
terrestrial
dicot
plants
exceed
the
acute
LOC
for
terrestrial
plants
in
semi­
aquatic
areas
at
the
maximum
application
rate
for
turf
(
RQ=
2.1
­
2.5).
The
RQs
for
listed
terrestrial
dicots
in
semi­
aquatic
areas
exceed
the
LOC
for
use
on
grasses
grown
for
seed,
rice,
wild
rice,
peanut,
and
turf
use.

However,
there
is
some
uncertainty
in
this
finding
of
risk
due
to
assumptions
included
in
the
TERR­
PLANT
model
used
to
derive
the
RQs.
TERR­
PLANT
assumes
a
default
amount
of
runoff
(
2
%
for
propiconazole)
from
each
of
ten
acres
to
non­
target
plants
in
an
adjacent
acre
based
on
the
solubility
of
the
pesticide.
The
Agency
is
currently
developing
a
plant
exposure
model
which,
among
other
things,
will
use
PRZM
to
estimate
the
amount
of
pesticide
in
runoff
based
on
the
persistence
and
mobility
of
the
chemical,
and
soil
and
weather
data
in
specific
crop
scenarios.
Although
this
refined
exposure
model
is
not
yet
available,
the
transport
of
propiconazole
in
runoff
from
use
on
turf
was
estimated
by
PRZM
as
part
of
the
aquatic
risk
assessment,
and
can
be
used
to
further
characterize
the
potential
for
risk
to
terrestrial
dicots.
The
TERR­
PLANT
model
assumed
an
EEC
of
0.36
lb
ai/
A
from
a
single
application
of
1.78
lb
ai/
A
on
turf.
The
transport
of
propiconazole
from
the
peak
runoff
event
for
each
of
30
years
simulated
by
PRZM
ranged
from
0.009
lb
ai/
A
to
0.245
lb
ai/
A.
These
EECs,
which
reflect
4
applications
of
propiconazole
at
1.78
lb
ai/
A,
would
result
in
acute
RQs
ranging
from
0.05
to
1.4
if
used
in
the
risk
assessment.
Peak
storm
events
simulated
by
PRZM
would
result
in
RQs
at
or
above
the
LOC
of
1.0
in
7
of
the
30
years
simulated,
indicating
a
potential
risk
to
plants
adjacent
to
treated
fields
under
certain
conditions
if
the
maximum
rate
and
number
of
applications
are
applied.

Method
Runoff
flux
was
evaluated
using
the
output
file
PPZPATuE.
ZPM
created
by
PRZM
for
application
of
propiconazole
in
the
Pennsylvania
turf
scenario.
This
PRZM
output
file
provides
a
cumulative
accounting
of
the
flux
of
propiconazole
in
runoff
and
adsorbed
to
sediments.
Since
the
erosion
flux
was
two
orders­
of­
magnitude
less
than
runoff
flux,
it
was
not
included
in
this
assessment.

The
daily
runoff
flux
was
scanned
to
identify
the
day
on
which
a
storm
event
transported
the
greatest
amount
of
propiconazole
to
the
edge
of
the
field
each
year.
The
amount
of
propiconazole
transported
that
day
was
determined
by
subtracting
the
cumulative
runoff
flux
from
the
previous
day
from
the
runoff
flux
from
the
day
of
the
storm
event.
The
maximum
daily
flux
event
for
each
of
the
30
years
is
shown
below
in
Table
1.
The
PRZM
output
file
generates
runoff
flux
values
in
g/
cm2
x
10E­
5.
For
comparison
to
the
assumed
runoff
flux
of
0.36
lb­
ai/
A
in
the
TERR­
PLANT
model,
the
maximum
annual
runoff
flux
is
shown
in
lb­
ai/
A
in
the
column
to
the
right.

Results
Risk
quotients
in
the
table
below
were
calculated
by
dividing
the
exposure
in
lb­
ai/
A
by
the
toxicity
endpoint
for
propiconazole;
i.
e.
the
application
rate
that
caused
an
adverse
effect
on
seedling
emergence
in
25%
of
test
plants
for
the
most
sensitive
species
tested
(
0.18
lb­
ai/
A
for
cabbage).
Table
1
below
shows
that
the
level­
of­
concern
(
LOC)
of
1.0
is
exceeded
for
7
of
the
30
years
simulated.
RQs
for
five
of
those
years
range
from
1.01
to
1.08,
and
the
two
highest
RQs
are
1.19
and
1.36.
RQs
from
the
other
23
years,
which
do
not
exceed
the
LOC,
range
from
0.05
to
0.99.

Table
1.
Runoff
flux
simulated
by
PRZM
(
PA
Turf)
and
corresponding
RQs
Year
Runoff
flux
Runoff
flux
RQ
Date
of
storm
event
g/
cm
2
x
10E
­
5
lb­
ai/
A
1961
0.021
0.1875
1.04
15­
May
1962
0.009
0.080357
0.45
15­
Jun
1963
0.0077
0.06875
0.38
12­
Sep
1964
0.0011
0.009821
0.05
30­
Apr
1965
0.001
0.008929
0.05
22­
Aug
1966
0.0023
0.020536
0.11
21­
Sep
1967
0.0218
0.194643
1.08
18­
Jun
1968
0.007
0.0625
0.34
30­
May
1969
0.0216
0.192857
1.07
28­
Jul
1970
0.0045
0.040179
0.22
20­
Jul
1971
0.0117
0.104464
0.58
1­
Aug
1972
0.02
0.178571
0.99
22­
Jun
1973
0.0275
0.245536
1.36
24­
Jun
1974
0.0064
0.057143
0.32
17­
Aug
1975
0.0027
0.024107
0.13
5­
Jun
1976
0.024
0.214286
1.19
8­
Aug
1977
0.0018
0.016071
0.09
19­
Jul
1978
0.0097
0.086607
0.48
7­
Aug
1979
0.0059
0.052679
0.29
6­
Sep
1980
0.0012
0.010714
0.06
25­
Oct
1981
0.0026
0.023214
0.13
11­
May
1982
0.0212
0.189286
1.05
8­
Aug
1983
0.0039
0.034821
0.19
20­
Jun
1984
0.0204
0.182143
1.01
29­
May
1985
0.0171
0.152679
0.85
26­
Jul
1986
0.0038
0.033929
0.19
16­
Apr
1987
0.0168
0.15
0.83
9­
Aug
1988
0.0172
0.153571
0.85
19­
May
1989
0.0025
0.022321
0.12
20­
Sep
1990
0.017
0.151786
0.84
6­
Aug
The
final
column
in
the
table
reports
the
date
on
which
the
greatest
simulated
daily
runoff
flux
event
occurred
in
each
year.
The
range
of
dates
illustrates
that
the
storm
event
which
causes
the
greatest
amount
of
pesticide
flux
from
the
field
can
occur
any
time
in
the
growing
season.
This
is
important
because
the
adverse
effect
reflected
in
the
RQs,
seedling
emergence,
will
not
occur
if
exposed
plants
have
already
germinated
and
grown
from
seed.
As
shown
in
the
Table
1,
the
runoff
events
for
three
of
the
seven
years
for
which
RQs
exceed
the
LOC
occurred
on
July
28
or
later.
