1
UNITED
STATES
ENVIRONMENTAL
PROTECTION
AGENCY
WASHINGTON,
D.
C.
20460
OFFICE
OF
PREVENTION,
PESTICIDES
AND
TOXIC
SUBSTANCES
Chemical:
Propiconazole,
Triadimerol
PC
Code:
122101,
127201
DP
Barcode:
D329230,
D329271
MEMORANDUM
DATE:
June
15,
2006
SUBJECT:
Response
to
Triazole
Task
Force
Comments
on
the
FQPA
Drinking
Water
Assessment
for
1,2,4­
Triazole
(
1,2,4­
T),
Triazole
alanine
(
TA),
and
Triazole
acetic
acid
(
TAA).

FROM:
James
Hetrick,
Ph.
D.,
Senior
Physical
Scientist
Iwona
Maher,
Chemist
Nancy
Andrews,
Ph.
D,
Branch
Chief
Environmental
Risk
Branch
1
Environmental
Fate
and
Effects
Division
(
7507P)

TO:
Susan
Lewis,
RM
51,
Branch
Chief
Special
Review
and
Reregistration
Division
(
7505C
)

This
memorandum
provides
a
response
to
the
Triazole
Task
Force
(
TTF)
Comments
on
the
EFED
FQPA
drinking
water
assessment
for
1,2,4­
T,
TA,
and
TAA.
The
TFF
stated
the
revised
drinking
water
assessment
has
major
errors
because
of
incorrect
PRZM/
EXAMS
model
input
parameters
as
well
as
the
use
of
erroneous
assumptions.
The
registrant
comments
and
EFED
responses
are
summarized
below.

1.
TTF
Comment:
The
foliar
extraction
(
FEXTRC)
parameter
should
be
set
to
0.5
for
foliar
applications
as
per
EFED
input
parameter
guidance.
2
EFED
Response:
EFED
agrees
the
foliar
extraction
parameter
(
FEXTRC)
should
be
set
to
0.5
for
foliar
pesticide
applications.
In
the
EFED
assessment,
it
was
assumed
triazole
residues
are
foliar
applied
(
CAM=
2)
to
turf
and
apples.
Although
this
assumption
is
probably
correct
for
turf,
it
may
be
inappropriate
for
apples.
EFED
revised
the
modeling
to
incorporate
the
default
foliar
extraction
parameter
(
Table
1).

Table
1.
1,2,4­
Triazole
estimated
drinking
water
concentrations
from
surface
water
sources
(
FEXTRC
=
0.5).
Estimated
Drinking
Water
Concentrations
(
ppb)
Scenario
Annual
Fungicide
Application
Rate
(
lb
ai/
acre)
Aerobic
soil
metabolism
T1/
2
1
in
10
year
annual
peak
1
in
10
year
annual
mean
36
year
annual
mean
PA
golf
course
turf
(
PCA
=
1)
1.3
x
6
=
7.8
107
days
4.04
1.56
0.71
NC
apples
(
PCA
=
0.87)
1.0
x
2
=
2.0
107
days
4.48
1.10
0.40
2.
TTF
Comment:
The
registrant
stated
the
assumption
of
100%
conversion
of
1,2,4­
T
to
TA
or
TAA
is
incorrect.
The
registrant
referenced
aerobic
soil
metabolism
studies
(
MRID
45297203,
45284027,
45284032,
45284038)
showing
the
maximum
formation
percentage
of
TAA
at
18%
of
applied
radioactivity
and
TA
as
not
detectable
(
0
%
of
applied
radioactivity).
Additionally,
they
stated
that
separate
PRZM/
EXAMS
simulations
were
possible
for
TAA
because
the
TTF
submitted
aerobic
soil
metabolism
and
adsorption/
desorption
data
(
MRID
46017601)
for
TAA.
PRZM/
EXAMS
simulations
for
TA
are
not
needed
because
this
degradation
product
is
not
found
in
aerobic
soil
metabolism
studies.

EFED
Response:
The
assumption
of
100%
conversion
of
1,2,4­
T
to
TA
and
TAA
was
used
to
provide
screening
level
concentrations
of
TA
and
TAA
in
drinking
water.
This
approach
was
used
because
it
is
unclear
on
the
extent
of
transformation
of
1,2,4­
T
to
TA
and
TAA
in
aquatic
environments.
Prothioconazole,
for
example,
formed
41.8%
of
triazole
in
the
total
water/
sediment
system
(
37.2%
in
the
water
column
and
6.1%
in
soil)
at
120
days
post­
treatment,
which
was
the
last
sampling
interval
in
the
laboratory
aerobic
aquatic
metabolism
study
(
MRID
46246515).
More
importantly,
EFED
was
not
aware
on
the
submission
of
environmental
fate
data
(
MRID
46017601)
for
TAA.

3.
TTF
Comment:
The
registrant
expressed
concern
about
the
use
of
a
250
day
half­
life
for
triazole
modeling.
They
provided
an
email
from
Sid
Abel
(
former
ERB1
Branch
Chief)
stating
the
250
day
half­
life
value
will
not
be
used
in
the
drinking
water
assessment
because
it
was
derived
from
a
study
with
high
triazole
concentrations.
Such
concentrations
are
not
expected
in
the
environment.
3
EFED
Response:
EFED
agrees
the
triazole
modeling
using
the
250
day
half­
life
is
not
appropriate
for
modeling
of
1,2,
4­
T.
This
half­
live
value,
however,
was
used
in
addition
to
107
days
to
serve
as
upper
bound,
comparison
concentration.
It
was
not
intended
to
be
used
in
the
human
health
exposure
assessment.
More
importantly,
the
PRZM
model
is
not
sensitive
to
aerobic
soil
metabolism
half­
life
when
they
are
above
100
days.

4.
TTF
Comment:
The
registrant
stated
the
national
percent
cropped
area
(
PCA)
is
not
appropriate
for
triazole
assessment.
They
state
that
regional
PCAs
should
be
employed
for
the
apple
and
minor
crop
scenarios.

EFED
Response:
EFED
uses
the
regional­
based
PCAs
when
the
national­
based
corrected
drinking
water
estimated
concentrations
(
DWEC)
exceed
the
HED
exposure
endpoint.
More
importantly,
the
conazole
fungicides
can
be
used
on
numerous
major
and
minor
crops
in
broad
geographic
areas
which
limit
the
utility
of
the
regional
PCA
approach.
Additionally,
regional
PCAs
are
not
appropriate
for
turf
scenario
because
they
are
based
strictly
on
agricultural
crops.

5.
TTF
Comment:
The
registrant
stated
the
highest
label
rate
for
myclobutanil
is
7.8
lbs
a.
i./
A/
season.
They
believe
the
myclobutanil
application
rate
of
10.38
lbs
ai./
A
does
not
represent
a
valid
myclobutanil
label.

EFED
Response:
EFED
modeled
turf
for
the
seasonal
application
rates
of
10.38
lbs
of
a.
i./
acre
(
EPA
Reg.
No.
62719­
417).
EFED
revised
the
PRZM/
EXAMS
modeling
on
turf
to
represent
the
7.8
lbs
a.
i./
A
(
Table
1).
4
Appendix
1
PRZM­
EXAMS
Output
Files
Turf
Application
in
PA
at
1.3
lb
ai/
acre
applied
six
times
(
the
aerobic
half­
life
107
days)

stored
as
triazolePAturf2006.
out
Chemical:
triazole
PRZM
environment:
PAturfC.
txt
modified
Monday,
24
November
2003
at
14:
49:
51
EXAMS
environment:
ir298.
exv
modified
Thuday,
29
August
2002
at
16:
34:
12
Metfile:
w14737.
dvf
modified
Wedday,
3
July
2002
at
10:
06:
12
Water
segment
concentrations
(
ppb)

Year
Peak
96
hr
21
Day
60
Day
90
Day
Yearly
1961
2.859
2.806
2.596
2.269
2.038
0.7318
1962
1.02
1.005
0.9342
0.8053
0.8189
0.5625
1963
0.332
0.3275
0.3093
0.2726
0.2481
0.1393
1964
0.1226
0.1204
0.1114
0.1028
0.09537
0.05267
1965
0.05683
0.05581
0.05298
0.04558
0.04117
0.02403
1966
0.2487
0.2441
0.2261
0.1957
0.1762
0.06366
1967
8.924
8.762
8.408
7.514
6.737
2.703
1968
2.096
2.067
1.952
1.72
1.566
0.8627
1969
1.13
1.112
1.038
0.8847
0.7911
0.3462
1970
1.118
1.098
1.052
0.9129
0.8158
0.3847
1971
0.7455
0.7329
0.689
0.588
0.525
0.3378
1972
5.373
5.308
4.942
4.588
4.247
1.878
1973
3.733
3.664
3.389
2.871
2.55
1.412
1974
1.608
1.58
1.473
1.309
1.228
0.7927
1975
1.089
1.069
0.9993
0.8884
0.8722
0.481
1976
1.39
1.372
1.273
1.085
0.973
0.4236
1977
0.8181
0.8027
0.7431
0.6302
0.561
0.3642
1978
1.244
1.221
1.13
1.039
0.9572
0.5163
1979
2.764
2.737
2.572
2.198
2.063
1.057
1980
0.7413
0.7313
0.6907
0.6086
0.5541
0.2886
1981
1.046
1.027
0.9507
0.8531
0.8257
0.3765
1982
2.934
2.884
2.687
2.426
2.376
1.137
1983
1.119
1.099
1.019
0.865
0.78
0.5368
1984
2.913
2.859
2.73
2.438
2.203
1.023
1985
1.842
1.808
1.689
1.433
1.278
0.7137
1986
1.011
0.9942
0.9247
0.7993
0.7336
0.4345
1987
1.492
1.466
1.359
1.159
1.043
0.4993
1988
1.855
1.827
1.715
1.45
1.291
0.6486
1989
1.854
1.82
1.728
1.592
1.494
0.8169
1990
4.069
3.996
3.703
3.285
3.069
1.572
Sorted
results
Prob.
Peak
96
hr
21
Day
60
Day
90
Day
Yearly
0.032258064516129
8.924
8.762
8.408
7.514
6.737
2.703
0.0645161290322581
5.373
5.308
4.942
4.588
4.247
1.878
0.0967741935483871
4.069
3.996
3.703
3.285
3.069
1.572
0.129032258064516
3.733
3.664
3.389
2.871
2.55
1.412
0.161290322580645
2.934
2.884
2.73
2.438
2.376
1.137
0.193548387096774
2.913
2.859
2.687
2.426
2.203
1.057
0.225806451612903
2.859
2.806
2.596
2.269
2.063
1.023
0.258064516129032
2.764
2.737
2.572
2.198
2.038
0.8627
0.290322580645161
2.096
2.067
1.952
1.72
1.566
0.8169
0.32258064516129
1.855
1.827
1.728
1.592
1.494
0.7927
0.354838709677419
1.854
1.82
1.715
1.45
1.291
0.7318
0.387096774193548
1.842
1.808
1.689
1.433
1.278
0.7137
0.419354838709677
1.608
1.58
1.473
1.309
1.228
0.6486
0.451612903225806
1.492
1.466
1.359
1.159
1.043
0.5625
0.483870967741936
1.39
1.372
1.273
1.085
0.973
0.5368
5
0.516129032258065
1.244
1.221
1.13
1.039
0.9572
0.5163
0.548387096774194
1.13
1.112
1.052
0.9129
0.8722
0.4993
0.580645161290323
1.119
1.099
1.038
0.8884
0.8257
0.481
0.612903225806452
1.118
1.098
1.019
0.8847
0.8189
0.4345
0.645161290322581
1.089
1.069
0.9993
0.865
0.8158
0.4236
0.67741935483871
1.046
1.027
0.9507
0.8531
0.7911
0.3847
0.709677419354839
1.02
1.005
0.9342
0.8053
0.78
0.3765
0.741935483870968
1.011
0.9942
0.9247
0.7993
0.7336
0.3642
0.774193548387097
0.8181
0.8027
0.7431
0.6302
0.561
0.3462
0.806451612903226
0.7455
0.7329
0.6907
0.6086
0.5541
0.3378
0.838709677419355
0.7413
0.7313
0.689
0.588
0.525
0.2886
0.870967741935484
0.332
0.3275
0.3093
0.2726
0.2481
0.1393
0.903225806451613
0.2487
0.2441
0.2261
0.1957
0.1762
0.06366
0.935483870967742
0.1226
0.1204
0.1114
0.1028
0.09537
0.05267
0.967741935483871
0.05683
0.05581
0.05298
0.04558
0.04117
0.02403
0.1
4.0354
3.9628
3.6716
3.2436
3.0171
1.556
Average
of
yearly
averages:
0.706002
Inputs
generated
by
pe4.
pl
­
8­
August­
2003
Data
used
for
this
run:
Output
File:
triazolePAturf2006
Metfile:
w14737.
dvf
PRZM
scenario:
PAturfC.
txt
EXAMS
environment
file:
ir298.
exv
Chemical
Name:
triazole
Description
Variable
Name
Value
Units
Comments
Molecular
weight
mwt
69.07
g/
mol
Henry's
Law
Const.
henry
1.97e­
10
atm­
m^
3/
mol
Vapor
Pressure
vapr
1.65e­
3
torr
Solubility
sol
7.0e+
6
mg/
L
Kd
Kd
0.72
mg/
L
Koc
Koc
mg/
L
Photolysis
half­
life
kdp
0
days
Half­
life
Aerobic
Aquatic
Metabolism
kbacw
214
days
Halfife
Anaerobic
Aquatic
Metabolism
kbacs
504
days
Halfife
Aerobic
Soil
Metabolism
asm
107
days
Halfife
Hydrolysis:
pH
7
161
days
Half­
life
Method:
CAM
2
integer
See
PRZM
manual
Incorporation
Depth:
DEPI
0.1
cm
Application
Rate:
TAPP
.107
kg/
ha
Application
Efficiency:
APPEFF
1.0
fraction
Spray
Drift
DRFT
0.0
fraction
of
application
rate
applied
to
pond
Application
Date
Date
07­
05
dd/
mm
or
dd/
mmm
or
dd­
mm
or
dd­
mmm
Interval
1
interval
14
days
Set
to
0
or
delete
line
for
single
app.
Interval
2
interval
14
days
Set
to
0
or
delete
line
for
single
app.
Interval
3
interval
14
days
Set
to
0
or
delete
line
for
single
app.
Interval
4
interval
14
days
Set
to
0
or
delete
line
for
single
app.
Interval
5
interval
14
days
Set
to
0
or
delete
line
for
single
app.
Record
17:
FILTRA
IPSCND
1
UPTKF
Record
18:
PLVKRT
PLDKRT
FEXTRC
0.5
Flag
for
Index
Res.
Run
IR
IR
Flag
for
runoff
calc.
RUNOFF
total
none,
monthly
or
total(
average
of
entire
run)
6
Application
to
Apples
in
PA
at
1.0
lb
ai/
acre
applied
twice
(
the
aerobic
half­
life
107
days)

stored
as
triazoleNCapples2006.
out
Chemical:
triazole
PRZM
environment:
NCappleC.
txt
modified
Monday,
24
November
2003
at
14:
49:
39
EXAMS
environment:
ir298.
exv
modified
Thuday,
29
August
2002
at
16:
34:
12
Metfile:
w03812.
dvf
modified
Wedday,
3
July
2002
at
10:
05:
50
Water
segment
concentrations
(
ppb)

Year
Peak
96
hr
21
Day
60
Day
90
Day
Yearly
1965
1.738
1.697
1.54
1.257
1.085
0.3853
1966
2.991
2.924
2.695
2.389
2.083
0.782
1967
1.07
1.046
0.9628
0.8318
0.7504
0.3354
1968
0.5069
0.4949
0.467
0.3844
0.3366
0.1488
1969
0.577
0.5637
0.5202
0.4419
0.3861
0.1495
1970
0.06915
0.06775
0.0623
0.05537
0.05381
0.03088
1971
1.358
1.327
1.231
1.032
0.8926
0.3205
1972
2.852
2.788
2.646
2.271
1.973
0.7296
1973
4.876
4.766
4.422
3.999
3.488
1.297
1974
2.11
2.062
1.902
1.645
1.433
0.5958
1975
2.55
2.507
2.327
1.914
1.651
0.6206
1976
2.483
2.437
2.223
1.932
1.689
0.6489
1977
0.5074
0.4958
0.4501
0.4078
0.3656
0.1789
1978
1.474
1.44
1.359
1.164
1.01
0.3753
1979
0.5052
0.4936
0.4495
0.3956
0.345
0.1488
1980
5.777
5.652
5.264
4.248
3.627
1.274
1981
1.198
1.171
1.074
0.9364
0.8247
0.3873
1982
0.6178
0.6033
0.5553
0.4598
0.3954
0.1609
1983
0.5982
0.5846
0.5413
0.4517
0.3883
0.1478
1984
1.991
1.947
1.763
1.587
1.434
0.5528
1985
0.181
0.1775
0.1636
0.1368
0.12
0.06163
1986
0.5664
0.5535
0.5072
0.4117
0.3525
0.1264
1987
5.843
5.704
5.177
4.185
3.579
1.255
1988
0.5215
0.5114
0.4712
0.3939
0.3455
0.1765
1989
1.892
1.849
1.766
1.641
1.448
0.5467
1990
2.412
2.357
2.16
1.827
1.593
0.6138
Sorted
results
Prob.
Peak
96
hr
21
Day
60
Day
90
Day
Yearly
0.037037037037037
5.843
5.704
5.264
4.248
3.627
1.297
0.0740740740740741
5.777
5.652
5.177
4.185
3.579
1.274
0.111111111111111
4.876
4.766
4.422
3.999
3.488
1.255
0.148148148148148
2.991
2.924
2.695
2.389
2.083
0.782
0.185185185185185
2.852
2.788
2.646
2.271
1.973
0.7296
0.222222222222222
2.55
2.507
2.327
1.932
1.689
0.6489
0.259259259259259
2.483
2.437
2.223
1.914
1.651
0.6206
0.296296296296296
2.412
2.357
2.16
1.827
1.593
0.6138
0.333333333333333
2.11
2.062
1.902
1.645
1.448
0.5958
0.37037037037037
1.991
1.947
1.766
1.641
1.434
0.5528
0.407407407407407
1.892
1.849
1.763
1.587
1.433
0.5467
0.444444444444444
1.738
1.697
1.54
1.257
1.085
0.3873
0.481481481481481
1.474
1.44
1.359
1.164
1.01
0.3853
0.518518518518518
1.358
1.327
1.231
1.032
0.8926
0.3753
0.555555555555556
1.198
1.171
1.074
0.9364
0.8247
0.3354
0.592592592592593
1.07
1.046
0.9628
0.8318
0.7504
0.3205
0.62962962962963
0.6178
0.6033
0.5553
0.4598
0.3954
0.1789
0.666666666666667
0.5982
0.5846
0.5413
0.4517
0.3883
0.1765
0.703703703703704
0.577
0.5637
0.5202
0.4419
0.3861
0.1609
0.740740740740741
0.5664
0.5535
0.5072
0.4117
0.3656
0.1495
0.777777777777778
0.5215
0.5114
0.4712
0.4078
0.3525
0.1488
0.814814814814815
0.5074
0.4958
0.467
0.3956
0.3455
0.1488
0.851851851851852
0.5069
0.4949
0.4501
0.3939
0.345
0.1478
0.888888888888889
0.5052
0.4936
0.4495
0.3844
0.3366
0.1264
0.925925925925926
0.181
0.1775
0.1636
0.1368
0.12
0.06163
0.962962962962963
0.06915
0.06775
0.0623
0.05537
0.05381
0.03088
7
0.1
5.1463
5.0318
4.6485
4.0548
3.5153
1.2607
Average
of
yearly
averages:
0.463465769230769
Inputs
generated
by
pe4.
pl
­
8­
August­
2003
Data
used
for
this
run:
Output
File:
triazoleNCapples2006
Metfile:
w03812.
dvf
PRZM
scenario:
NCappleC.
txt
EXAMS
environment
file:
ir298.
exv
Chemical
Name:
triazole
Description
Variable
Name
Value
Units
Comments
Molecular
weight
mwt
69.07
g/
mol
Henry's
Law
Const.
henry
1.97e­
10
atm­
m^
3/
mol
Vapor
Pressure
vapr
1.65e­
3
torr
Solubility
sol
7.0e+
6
mg/
L
Kd
Kd
0.72
mg/
L
Koc
Koc
mg/
L
Photolysis
half­
life
kdp
0
days
Half­
life
Aerobic
Aquatic
Metabolism
kbacw
214
days
Halfife
Anaerobic
Aquatic
Metabolism
kbacs
504
days
Halfife
Aerobic
Soil
Metabolism
asm
107
days
Halfife
Hydrolysis:
pH
7
161
days
Half­
life
Method:
CAM
2
integer
See
PRZM
manual
Incorporation
Depth:
DEPI
0.1
cm
Application
Rate:
TAPP
0.082
kg/
ha
Application
Efficiency:
APPEFF
1.0
fraction
Spray
Drift
DRFT
0.0
fraction
of
application
rate
applied
to
pond
Application
Date
Date
01­
05
dd/
mm
or
dd/
mmm
or
dd­
mm
or
dd­
mmm
Interval
1
interval
7
days
Set
to
0
or
delete
line
for
single
app.
Record
17:
FILTRA
IPSCND
1
UPTKF
Record
18:
PLVKRT
PLDKRT
FEXTRC
0.5
Flag
for
Index
Res.
Run
IR
IR
Flag
for
runoff
calc.
RUNOFF
total
none,
monthly
or
total(
average
of
entire
run)
