UNITED
STATES
ENVIRONMENTAL
PROTECTION
AGENCY
WASHINGTON
D.
C.,
20460
OFFICE
OF
PREVENTION,
PESTICIDES
AND
TOXIC
SUBSTANCES
PC
Code:
058001
DP
Barcode:
307569
DATE:
May
30,
2006
MEMORANDUM
SUBJECT:
Azinphos
Methyl 
EFED
Response
to
Stakeholder
Comments
on
the
Ecological
Risk
Assessment
for
"
Group
3"
Uses
FROM:
Colleen
Flaherty,
Biologist
(
ERB
3)
R.
David
Jones,
Chemist
(
ERB
4)
Environmental
Fate
and
Effects
Division
(
7507C)

THRU:
Daniel
Rieder,
Branch
Chief
(
ERB
3)
Elizabeth
Behl,
Branch
Chief
(
ERB
4)
Environmental
Fate
and
Effects
Division
(
7507C)

TO:
Diane
Isbell,
Risk
Manager
(
RRB
2)
Special
Review
and
Reregistration
Division
(
7505C)

Attached
please
find
the
Office
of
Pesticide
Program's
(
OPP's)
response
to
stakeholder
comments
on
the
ecological
risk
assessment
for
the
use
of
azinphos
methyl
on
apples,
blueberries
(
low­
and
high
bush),
Brussels
sprouts,
cherries
(
sweet
and
tart),
grapes,
nursery
stock,
parsley,
pears,
pistachios,
and
walnuts
(
i.
e.
"
Group
3
uses").
2
Cherry
Marketing
Institute
(
EPA­
HQ­
OPP­
2005­
0061­
0071)

1.
Comment
(
Page
3):
"
Using
tree­
row­
volume
technology
and
spraying
in
the
evening
and
at
night
when
the
winds
are
calm
is
a
critical
practice
that
most
growers
have
used
to
minimize
drift."

EFED
Response:
Tree­
row­
volume
technology
and
spraying
at
night
may
indeed
reduce
spray
drift.
However,
azinphos
methyl
is
extremely
toxic
to
aquatic
animals,
and
aquatic
exposures
of
azinphos
methyl
are
predominantly
runoff
driven
in
the
eastern
United
States.
Thus,
aquatic
risks
would
remain
even
if
these
spray
drift
mitigation
techniques
were
employed
universally
by
cherry
growers.

2.
Comment
(
Page
3):
"
CMI
believes
that
the
Agency
has
over­
estimated
the
ecological
risk
when
AZM
is
used
on
cherries.
Over
the
years,
there
have
not
been
any
adverse
incidents
resulting
from
the
use
of
AZM
reported
in
our
industry."

EFED
Response:
This
statement
assumes
that
there
is
a
rigorous
ecological
incident
monitoring
program
in
place.
This
is
not
the
case.
Based
on
laboratory
toxicity
data,
projected
environmental
exposures
for
azinphos
methyl
use
on
cherries,
and
field
studies
in
fruit
orchards
(
including
one
in
Michigan),
the
risks
to
aquatic
and
terrestrial
animals
remain.

Mark
Whalon
(
EPA­
HQ­
OPP­
2005­
0061­
0081)

1.
Comment
(
Page
4):
"
AZM
did
not
produce
detectable
residues
(
below
LOD)
in
processed
cherries
in
a
2­
year
independent
study
conducted
in
Michigan
(
1998­
9) 
these
data
did
not
find
their
way
into
any
of
USEPA's
ecological
or
benefit
analysis
on
AZM."

EFED
Response:
EFED
does
currently
consider
the
residues
on
fruit
at
harvest
for
use
in
the
ecological
risk
assessment,
although
it
is
an
important
part
of
the
human
health
risk
assessment.
Ecological
risks
accrue
between
application
and
harvest,
so
post­
harvest
data
are
not
relevant
for
our
assessments.

2.
Comment
(
Page
5­
11):
Acute
&
Chronic
Toxicity
Assessment:
Inference
to
Ecological
Sustainability;
beneficial
insect
indices.

EFED
Response:
EFED
agrees
that
chronic
(
e.
g.
reproductive,
growth)
effects
can
have
profound
ecological
consequences,
such
as
alteration
of
the
trophic
cascade,
reduction
in
biodiversity,
etc.
Chronic
azinphos
methyl
toxicity
studies
were
available
for
a
number
of
aquatic
and
terrestrial
animals,
and
these
studies
have
been
reviewed
and
incorporated
into
the
ecological
risk
assessment.

Dr.
Whalon's
comments
focus
on
the
ecology
of
beneficial
insects
in
agricultural
settings.
The
EPA
assessment
took
into
consideration
all
aquatic
and
terrestrial
animals
(
including
beneficial
insects)
and
plants
in
the
United
States.
The
aquatic
ecosystems
potentially
at
risk
include
water
bodies
adjacent
to
or
downstream
from
the
treated
field.
These
water
bodies
3
include
impounded
bodies
such
as
ponds,
lakes,
and
reservoirs;
and
flowing
waterways,
such
as
streams
and
rivers;
and
marine
ecosystems,
including
estuaries.
The
terrestrial
ecosystems
potentially
at
risk
include
the
treated
area
and
areas
immediately
adjacent
to
the
treated
area
that
might
receive
drift
or
runoff.
These
terrestrial
ecosystems
include
other
cultivated
fields,
fencerows,
hedgerows,
meadows,
fallow
fields,
grasslands,
woodlands,
riparian
habitats,
other
uncultivated
areas.

EPA's
ecological
risk
assessment
concluded
that
all
of
the
remaining
azinphos
methyl
uses
pose
chronic
(
and
acute)
risks
to
all
aquatic
and
terrestrial
animals
(
including
beneficial
insects).
These
risk
presumptions
are
supported
by
various
field
studies
and
adverse
ecological
incidents,
including
numerous
beneficial
insect
kills.

Bayer
CropScience
(
EPA­
HQ­
OPP­
2005­
0061­
0092)

1.
Comment
(
Page
4):
"
The
modeled
water
concentrations
that
were
used
in
the
aquatic
risk
assessment
(
Page
39,
Table
3.12)
were
much
higher
than
the
actual
concentrations
observed
in
monitoring."

EFED
Response:
Comparisons
between
modeling
and
monitoring
need
to
consider
(
among
other
things)
1)
differences
in
hydrologic
setting
between
the
modeled
scenario
and
the
monitoring
data;
2)
use
patterns
in
the
monitoring
data;
3)
the
return
frequency
in
the
modeling
versus
the
study
duration
for
the
monitoring;
4)
sampling
frequency
in
the
monitoring.

The
hydrologic
setting
for
the
aquatic
modeling
represents
a
pond
that
is
located
high
in
the
watershed
and
is
more
vulnerable
than
most
sites
where
the
specific
crop
is
grown.
The
watershed
is
assumed
to
be
dominated
by
the
production
of
a
single
crop.
It
is
a
surrogate
for
other
small
vulnerable
water
bodies
near
the
tops
of
watersheds
such
as
playa
lakes,
prairie
pot
holes,
vernal
pools,
and
first­
order
streams.
In
contrast,
most
monitoring
data
are
collected
on
larger
creeks,
rivers,
and
reservoirs
where
dilution
by
untreated
water
and
dissipation
processes
have
had
some
opportunity
to
reduce
the
concentration
from
that
of
water
bodies
close
to
the
application
site.
For
example,
in
the
Pilot
Reservoir
Monitoring
Study,
the
smallest
watershed
was
Lake
LeRoy
in
New
York,
with
an
area
of
3.3
square
miles.

In
order
to
evaluate
monitoring
data,
it
is
important
to
know
the
use
intensity
and
application
timing
in
the
basin
upstream
of
the
sampling
station.
However,
this
information
is
usually
not
available.
None
of
the
studies
listed
in
Bayer's
comment
(
Pilot
Reservoir
Monitoring
Study,
NAWQA,
STORET,
NAWQA
phase
pilot
monitoring
program,
and
the
Washington
State
Surface
Water
Monitoring
Program)
were
targeted
to
azinphos
methyl
usage
or
to
crops
on
which
azinphos
methyl
may
be
applied.
In
some
cases,
the
usage
or
potential
usage
can
be
evaluated
post
hoc,
as
was
done
for
the
final
EFED
ecological
risk
assessment
supporting
the
RED.

Monitoring
data
are
collected
from
several
sites,
but
only
a
few
years
in
time.
Simulation
4
modeling
represents
longer
periods
of
time
at
each
site.
Currently,
30
years
is
usually
simulated,
and
the
1­
in­
10
year
concentration
is
used
for
screening
risk
assessment.
The
1­
in­
10
year
concentration
will
be
greater
than
more
frequent
return
periods.
For
example,
for
the
Pennsylvania
apple
scenario,
the
1­
in­
10
year
return
value
with
a
25­
ft
buffer
was
15.0
µ
g
L­
1,
while
the
1­
in­
2
year
value
is
9.7
µ
g
L­
1.

Tier­
2
simulation
modeling
estimates
the
concentration
in
the
surrogate
water
body
every
day
for
30
years,
which
results
in
over
10,000
daily
concentration
estimates.
In
contrast,
monitoring
data
usually
only
have
a
few
measurements
at
each
location
due
the
relatively
large
expense
required
to
collect
and
analyze
each
sample.
Studies
with
a
high
frequency
of
monitoring
typically
have
12
to
20
samples
taken
in
a
year,
resulting
in
several
hundred
samples
analyzed
from
all
sites
in
the
course
of
the
study.
Unless
the
monitoring
study
is
correlated
with
pesticide
application
schedules,
it
is
unlikely
that
the
highest
concentrations
that
occur
during
the
study
period
will
be
captured.
Consequently,
using
monitoring
data
alone
to
assess
acute
aquatic
risks
will
usually
underestimate
the
actual
risks.
Monitoring
data
tend
to
be
more
useful
in
establishing
chronic
exposure
estimates
for
risk
assessment
purposes,
provided
that
the
sampling
schedule
adequately
captures
the
pesticide's
presence
at
the
sampling
site.

Based
on
the
combination
of
all
of
these
factors,
in
general,
monitoring
data
underestimate
the
exposure
of
pesticides
in
the
environment
especially
for
pesticides
where
the
short­
term
or
one­
time
exposure
elicits
an
effect
of
concern.
Tier­
2
modeling
is
used
by
EPA
as
a
screening
tool
and
may
overestimate
actual
exposures.
Real­
life
exposures
generally
lie
between
the
estimates
from
these
two
methods.

2.
Comment
(
Page
6):
"
The
label
specifies
medium
or
coarser
spray,
applications
when
wind
velocity
favors
on­
site
product
deposition,
use
during
dormant
season
prohibited "

EFED
Response:
EFED's
current
model
for
spray
drift
from
air
blast
is
a
regression
model
and
is
unable
to
account
for
spray
quality
(
e.
g.
medium
or
coarser
spray).
(
Note
that
the
labels
specify
spray
quality
only
for
aerial
and
ground
boom
applications).
Wind
speed
effects
also
cannot
be
directly
accounted
for
as
the
original
calculations
on
which
the
model
is
based
could
not
separate
wind
speed
effects
from
the
background
variability.
Contrary
to
the
comment,
EFED
did
not
simulate
a
dormant
application.
EFED
simulated
a
sparse
orchard
to
account
for
air
blast
spraying
over
the
top
of
the
orchard.
The
current
labels
indicate
that
this
practice
is,
in
fact,
restricted
on
the
label
("
To
minimize
spray
loss
over
the
top
in
orchard
applications,
spray
must
be
directed
into
the
canopy.")
and
a
new
simulation
has
been
prepared
that
uses
the
`
normal'
rather
than
the
sparse
orchard.
Additional
modeling
has
been
done
using
the
standard
orchard
("
Orchard"
in
AgDrift),
rather
than
the
sparse
orchard,
and
the
risks
to
aquatic
animals
remain.

3.
Comment
(
page
6):
"
Increasing
drift
value
by
a
factor
of
three
was
not
necessary,
since
the
value
generated
by
AgDrift
was
already
conservative."

EFED
Response:
As
noted
above,
the
spray
blast
model
in
AgDrift
is
a
regression
model,
and
as
such,
predicts
the
mean
estimate
across
the
trials
that
were
used
in
the
regression
5
calculation.
Consequently,
about
half
of
the
time,
the
spray
drift
deposition
will
be
higher;
the
other
half
of
the
time,
it
will
be
lower.
Multiplying
the
pond
deposition
accounts
for
this
background
variability
and
assures
that
the
screening
estimate
will
be
conservative.

4.
Comment
(
Page
6):
"
Aerial
application
is
prohibited
on
the
label"

EFED
Response:
There
is
an
SLN
label
for
aerial
application
to
apples
in
Idaho.
The
estimate
with
aerial
application
only
applies
to
that
label.
The
Oregon
apples
scenario
was
used
as
a
surrogate
for
apples
grown
in
Idaho.
Ground
spray
application
was
also
modeled
for
apples.

5.
Comment
(
Page
6):
"
The
models
do
not
take
into
account
the
dilution
that
can
be
attributed
to
the
runoff
water
and
sediment
reaching
the
water
body.
Also,
the
models
do
not
take
into
account
the
mass
of
pesticide
removed
from
the
pond
by
overflow."

EFED
Response:
The
volume
of
the
pond
is
several
times
the
volume
of
runoff
from
a
10
hectare
field
even
in
the
largest
runoff
events.
For
example,
a
large
runoff
event
may
generate
5
cm
(
about
2
inches)
of
runoff
per
hectare,
which
is
equivalent
to
5
million
liters.
There
are
20
million
liters
in
the
pond,
so
the
dilution
in
the
pond
is
larger
than
that
for
dilution
in
the
runoff.
The
EXAMS
model
is
a
steady­
state
model,
and
it
cannot
estimate
storm­
by­
storm
runoff.
Setting
a
single
steady­
state
flow
tends
to
underestimate
potential
exposure
substantially,
partly
because
the
release
from
the
pond
is
too
great,
and
partly
because
real
ponds
also
evaporate,
which
concentrates
the
pesticide
between
storm
events.
Consequently,
the
pond
scenario
is
set
so
there
is
no
flow
out
of
the
water
body.
This
is
equivalent
to
assuming
that
evaporation
and
runoff
are
equal,
which
is
a
reasonable
assumption
for
many
small
static
water
bodies.

6.
Comment
(
Page
10­
11):
"
For
aquatic
species,
detailed
field
studies
have
been
conducted
by
a
number
of
researchers 
Based
on
the
results
of
these
studies,
Bayer
CropScience
believes
that
the
No
Observed
Adverse
Effects
Concentration
(
NOEAC)
for
azinphos­
methyl
to
aquatic
organisms
is
near
1
ppb
(
µ
g
a.
i./
L)."

EFED
Response:
The
studies
that
Bayer
CropScience
refers
to
suggest
that
a
single
exposure
of
azinphos
methyl
at
a
very
low
level
(
i.
e.
4
µ
g
a.
i./
L)
can
elicit
population­
level
effects
in
aquatic
ecosystems
(
Sierszen
and
Lozano,
1997).
At
this
level,
taxon
richness
(
diversity)
was
significantly
reduced,
and
recovery
of
zooplankton
populations
and
communities
took
one
month.
Most
of
the
remaining
azinphos
methyl
uses
allow
more
than
one
application
per
season,
and
we
would
expect
that
the
magnitude
of
the
population
declines
and
the
time
to
recover
would
increase
with
increasing
applications.

In
addition,
chronic
toxicity
studies
indicate
that
significant
reproductive
effects
can
occur
at
levels
well
below
1
µ
g
a.
i./
L.
In
a
21­
day
Daphnia
magna
chronic
toxicity
study,
significant
effects
on
survivorship,
length,
and
fecundity
(
mean
number
of
young
per
adult
per
reproductive
day)
were
observed
at
a
LOAEC
of
0.40
µ
g
a.
i./
L.
For
these
reasons,
a
NOAEC
of
1
µ
g
a.
i./
L
for
aquatic
organisms
(
as
suggested
in
the
comment)
would
not
be
adequately
protective
for
azinphos
methyl.
6
7.
Comment
(
Page
11):
" 
significant
reduction
in
both
aquatic
and
terrestrial
incidences
reported
in
association
to
labeled
uses "

EFED
Response:
Cancellation
of
the
use
of
azinphos
methyl
on
both
sugar
cane
and
cotton,
in
particular,
undoubtedly
reduced
the
ecological
risks
associated
with
this
chemical.
However,
the
risks
associated
with
the
remaining
uses
of
azinphos
methyl
are
still
very
high.
Our
assessment
concluded
that
there
are
acute
and
chronic
risks
to
all
potentially
exposed
aquatic
and
terrestrial
animals
for
all
of
the
remaining
labeled
uses.

Further,
the
trend
of
decreasing
adverse
ecological
incidents
in
the
EIIS
database
is
not
unique
to
azinphos
methyl.
Reports
of
adverse
ecological
incidents
have
dropped
dramatically
since
1995.
We
suspect
that
this
decline
is
more
of
a
result
of
reduced
reporting
rather
than
to
a
drastic
decrease
in
pesticide
risk
to
fish
and
wildlife.

8.
Comments
(
Page
14):
" 
While
model
predictions
indicate
dietary
exposure
via
residues
in
excess
of
mortality
thresholds,
no
terrestrial
incidence
has
appeared
in
the
EIIS
Pesticide
Report
since
1999.
BCS
feels
this
is
indicative
of
the
probability
of
effects
likely
elicited
in
the
field
with
current
use
patterns."

(
Page
14):
"
The
reference
to
terrestrial
incidents
should
be
qualified
with
the
fact
that
none
have
been
reported
since
1999.
BCS
believes
this
is
related
to
current
label
uses
and
the
reduced
probability
of
effects."

(
Page
18):
"
Former
field
incidences
are
not
in
line
with
current
trends
associated
with
current
uses.
No
terrestrial
incidence
has
appeared
in
the
EIIS
Pesticide
Report
since
1999."

(
Page
18):
"
While
LOCs
are
exceeded
for
these
uses,
terrestrial
incidence
reports
have
not
occurred
since
1999."

(
Page
23):
"
The
assumption
that
mitigation
measures
would
not
reduce
risk
potential
is
unsubstantiated.
While
the
Agency's
LOCs
have
been
exceeded
for
terrestrial
for
many
uses
patterns
the
predicted
effects
have
not
been
realized
under
true
field
exposure
condition
in
recent
years
(
i.
e.
no
terrestrial
incidence
reports
since
1999)."

(
Page
23):
"
No
terrestrial
incidence
has
been
reported
since
1999.
BCS
believes
this
to
be
a
direct
correlation
to
use
mitigation
and
effective
best
management
practices
employed
since
that
time."

EFED
Response:
These
statements
assume
that
there
is
a
rigorous
ecological
incident
monitoring
program
in
place.
Wildlife
incidents
from
exposure
to
an
environmental
stressor
may
go
unnoticed
by
humans
because
dead
wildlife
can
be
easily
overlooked,
even
by
experienced
and
highly
motivated
observers.
Reasons
for
underreporting
of
wildlife
incidents
include:
7
­
Wildlife
carcass
detection
is
difficult
in
areas
with
sparse
vegetative
cover
and
nearly
impossible
where
there
is
dense
vegetative
growth.
­
Birds
may
fly
from
the
poisoning
site,
and
intoxicated
animals
often
seek
cover
before
dying.
­
Scavengers
may
remove
carcasses
before
they
can
be
observed
by
humans.
Balcomb
et
al.
(
1984)
reported
that
the
removal
rate
of
songbird
carcasses
by
scavengers
ranged
from
62
to
92
percent
in
the
first
24
hours
following
placement.
­
The
density
of
live
birds
in
agricultural
settings
is
typically
low.
Thus,
even
if
all
the
birds
in
a
field
were
killed
and
remained
on
the
field,
the
probability
of
detecting
carcasses,
particularly
when
not
systematically
searching,
is
very
low.
Even
when
highly­
trained
individuals
conduct
systematic
searches
for
placed
carcasses
in
agricultural
environments,
recovery
rates
rarely
exceed
50
percent
(
Madrigal
et
al.,
1996).
­
If
wildlife
kills
are
observed,
they
are
not
always
reported
to
the
Agency.
Those
unfamiliar
with
the
potential
ecological
effects
of
pesticides
may
fail
to
associate
the
dead
wildlife
with
a
pesticide
application,
especially
if
the
two
events
are
separated
by
several
days
or
the
kill
magnitude
is
low.
If
the
observer
makes
the
connection,
he
must
still
be
motivated
enough
to
report
the
incident
to
the
Agency.

Further,
the
trend
of
decreasing
adverse
ecological
incidents
in
the
EIIS
database
is
not
unique
to
azinphos
methyl.
Reports
of
adverse
ecological
incidents
have
dropped
dramatically
since
1995.
We
suspect
that
this
decline
is
more
of
a
result
of
reduced
reporting
rather
than
to
a
drastic
decrease
in
pesticide
risk
to
fish
and
wildlife.

9.
Comment
(
Page
15):
"
EFED
presents
no
argument
supporting
the
expected
commensurate
toxicity
associated
with
azinphos­
methyl
degradates.
It
is
unreasonable
to
assume
degradates
would
magnify
potential
risk
to
aquatic
organisms
without
factual
substance.
This
statement
by
EFED
is
later
contradicted
on
page
20
of
the
EFED
risk
assessment
as
follows:
"
Furthermore,
none
of
the
degradates
that
are
produced
by
metabolic
pathways,
which
are
the
primary
routes
of
degradation
for
azinphos­
methyl,
are
present
at
any
time
at
concentrations
greater
than
10%
of
the
nominal
starting
concentration
of
the
parent,
so
they
would
not
be
expected
to
contribute
substantially
to
total
toxicity
of
azinphosmethyl
in
the
environment."

EFED
Response:
The
risks
from
the
parent
alone
exceed
the
risk
thresholds.
There
are
some
environmental
degradates,
particularly
the
azinphos
methyl
oxon,
that
are
potentially
toxic.
Oxons
of
other
organodithiophosphates
are
more
toxic
than
the
parent.
OPP
often
makes
a
default
assumption
that
degradates
are
of
equal
toxicity
to
the
parent
when
data
has
not
been
provide
to
the
contrary.
However,
azinphos
methyl
degradates
have
not
been
found
in
the
significant
quantities
in
the
environment,
and
they
were
not
considered
quantitatively
in
the
risk
assessment.
To
the
extent
they
are
present
they
increase
the
risk
above
what
has
been
estimated
for
parent,
which
is
already
above
the
Agency's
levels
of
concern
for
nontarget
species.

10.
Comment
(
Page
16):
"
No
aerial
use
is
included
on
the
pending
label
in
Idaho."
8
EFED
Response:
There
is
still
an
active
24(
c)
in
Idaho
for
aerial
application
on
apples.
The
SLN
number
is
ID000006.

11.
Comment
(
Page
16):
"
The
pending
use
label
does
not
include
grapes."

EFED
Response:
At
the
time
the
assessment
was
written,
there
was
an
active
24(
c)
for
azinphos
methyl
use
on
California
grapes.

12.
Comment
(
Page
16):
"
The
pending
Group
3
label
for
azinphos­
methyl
states
that
a
medium
to
coarse
spray
nozzle
should
be
used
(
according
to
ASAE
572
definition
for
standard
nozzles)
for
ground
boom
and
aerial
applications.
AgDrift
inputs
should
have
been
made
using
a
medium
to
coarse
droplet
size."

EFED
Response:
EFED
agrees
that
the
assessment
of
aerial
application
for
Idaho
should
have
used
a
medium
spray.
However,
the
risk
conclusions
would
not
change
if
medium
spray
was
used
for
this
use.

13.
Comment
(
Page
17):
"
The
Guthion
Solupack
label
(
264­
733)
is
pending
for
the
current
uses
included
in
this
assessment.
Therefore,
broadcast
spray
for
Brussels
sprouts
should
not
be
included.
Incorporation
or
in
furrow
spraying
should
have
been
assessed
thus
reducing
spray
drift
potential."

EFED
Response:
The
current
label
allows
broadcast
spray
on
Brussels
sprouts
and
that
practice
was
the
one
used
for
the
risk
assessment.
If
Bayer
has
submitted
alternative
use
language
for
Brussels
sprouts,
it
can
be
evaluated
as
part
of
the
continuing
re­
evaluation
process
for
azinphos
methyl.

14.
Comment
(
Page
17):
"
The
pending
Group
3
label
for
azinphos­
methyl
does
not
include
aerial
application
to
apples."

EFED
Response:
There
is
still
an
active
24(
c)
in
Idaho
for
aerial
application
on
apples.
The
SLN
number
is
ID000006.

15.
Comment
(
Page
17):
"
The
vast
majority
of
these
130
reported
adverse
aquatic
incidences
come
from
the
late
1980'
s
and
early
1990'
s
on
uses
no
longer
labeled
and
are
therefore
not
relevant
to
current
label
uses."

EFED
Response:
Cancellation
of
the
use
of
azinphos
methyl
on
both
sugar
cane
and
cotton,
in
particular,
undoubtedly
reduced
the
ecological
risks
associated
with
this
chemical.
However,
the
risks
associated
with
the
remaining
uses
of
azinphos
methyl
are
still
very
high.
Our
assessment
concluded
that
there
are
acute
and
chronic
risks
to
all
potentially
exposed
aquatic
and
terrestrial
animals
for
all
of
the
remaining
labeled
uses.

16.
Comment
(
Page
22):
"
EFED
concludes
that
risk
quotients
suggest
expected
mortality
and/
or
sub­
lethal
effects,
incident
data
and
surface
water
monitoring
data
since
2001
(
since
significant
mitigating
practices
have
been
implemented)
suggest
a
low
probability
9
of
such
effects."

EFED
Response:
As
discussed
above,
because
monitoring
data
generally
underestimate
acute
risk,
it
cannot
be
used
to
rule
out
risk
above
the
level
of
concern.
Further,
the
slope
of
the
dose­
response
curve
for
azinphos
methyl
is
very
steep,
and
small
exceedance
of
effects
thresholds
can
elicit
profound
ecological
effects.

17.
Comment
(
Page
24):
"
The
studies
performed
were
level
1
field
studies
which
are
designed
to
provide
only
qualitative
information
about
effects.
They
were
not
designed
to
quantify
the
magnitude
of
effects
occurring."

EFED
Response:
These
field
studies
were
used
in
a
qualitative
manner
and
only
to
provide
additional
lines
of
evidence
in
the
ecological
risk
assessment.

U.
S.
Apple
Association
(
EPA­
HQ­
OPP­
2005­
0061­
0087.2)

1.
Comment
(
Page
2):
" 
spray
drift
model
assumes
that
wind
is
always
blowing
in
the
direction
of
its
hypothetical
farm
pond
at
the
highest
allowable
wind
velocity,
the
vegetation
cover
is
sparse
and
the
drift
value
is
multiplied
by
three.
The
water
model
calculates
loading
of
the
pesticide
in
the
pond
assuming
that
all
orchards
are
composed
of
soils
with
high
runoff
potential.
Additionally,
the
water
model
counts
pesticide
runoff
carried
by
water
into
the
pond,
counting
only
the
pesticide
deposition
and
not
the
water .
This
model
compounds
the
pesticide
loading
scenario
by
restricting
natural
out
flow
of
the
pond.
Also,
it
does
not
count
the
run
off
reduction
from
the
25
foot
buffer
which
is
required
on
the
azinphos
methyl
label,
and
it
does
not
include
the
run
off
reduction
from
a
vegetative
buffer
between
the
pond
and
the
hypothetical
farm
field.
This
assumption
contradicts
the
real
scenario
in
apple
production.
These
assumptions
reflect
the
most
conservative
scenario
for
azinphos
methyl
use,
not
a
realistic
scenario."

EFED
Response:
The
U.
S.
apple
association
is
correct
that
EFED
modeling
assumes
that
the
wind
is
always
blowing
directly
at
the
pond.
Currently,
available
spray
drift
models
do
not
have
the
capability
to
account
for
wind
direction,
so
assuming
that
the
wind
always
blows
towards
the
pond
allows
the
assessment
of
spray
drift
in
the
absence
of
such
a
capability.
Sparse
orchards
can
be
used
to
represent
dormant
applications
(
which
are
prohibited
on
the
label)
as
well
as
applications
to
immature
orchards
and
to
address
the
drift
from
applications
that
go
over
the
top
of
the
canopy.
For
these
simulations,
it
was
this
last
case
(
over
the
top
of
the
canopy)
which
was
the
justification
for
using
the
sparse
orchard.
However,
there
is
language
on
the
label
which
indicates
that
practice
is
prohibited,
so
it
was
incorrect
to
use
a
sparse
orchard
on
that
basis.
Additional
modeling
has
been
performed
with
a
generic
orchard
rather
than
the
sparse
orchard
to
correct
this
error.
Predicted
exposures
are
somewhat
lower;
however,
risks
still
exceed
the
Agency's
level
of
concern.

The
modeling
considered
spray
drift
buffers,
but
not
run­
off
buffers.
A
high
runoff
potential
soil
is
used
in
the
scenario
so
that
the
simulation
will
account
for
the
most
sensitive
areas
where
there
are
apple
orchards,
in
general.
Vegetative
buffers
are
not
expected
to
meaningfully
reduce
azinphos
methyl
movement
to
water
unless
they
are
specifically
10
constructed
and
maintained
for
that
purpose.
Otherwise,
water
tends
to
flow
along
the
buffer
to
a
low
point
and
cross
the
buffer
as
concentrated
flow
with
little
or
no
mitigation
effect.
EFED
does
believe
that
the
use
of
constructed
and
maintained
Vegetated
Filter
Strips
(
USDA
NRCS
2000)
can
reduce
the
potential
for
runoff.
However,
tools
are
not
currently
available
to
quantify
the
expected
reduction
in
runoff
when
this
mitigation
practice
is
used.

An
explanation
for
dilution
effects
in
pond
is
provided
in
the
response
to
comment
#
1
from
Bayer
CropScience.

2.
Comment
(
Page
2):
"
EPA's
modeling
scenario
utilizes
data
that
are
inconsistent
with
monitoring
data
measuring
real
azinphos
methyl
concentrations
in
water
bodies
across
the
United
States.
In
its
Pennsylvania
air
blast
modeling
scenario
EPA
generates
a
concentration
of
15.1
parts
per
billion
(
ppb)
and
9.9
ppb
for
its
Oregon
air
blast
scenario.
However,
STORET
and
U.
S.
Geological
Survey
(
USGS)
monitoring
data
indicate
azinphos
methyl
concentrations
are
mostly
1
ppb
or
less,
with
two
peak
values
of
less
than
4
ppb
between
1990
and
2005.
After
2001,
the
highest
concentrations
from
actual
monitoring
data
were
0.75
ppb
in
Oregon
and
less
than
0.05
ppb
in
Pennsylvania."

EFED
Response:
Explanation
for
differences
in
modeling
and
monitoring
are
discussed
in
the
response
to
comment
#
1
from
Bayer
CropScience.

3.
Comment
(
Page
2):
" 
EPA's
ecological
risk
assessment
fails
to
provide
the
full
context
when
discussing
azinphos
methyl
detections
in
Washington
state.
While
stating
on
pages
39­
40
that
azinphos
methyl
was
detected
in
a
high
percentage
of
samples
collected
by
USGS
in
1999
and
2000,
the
agency
does
not
mention
that
more
than
95
percent
of
the
detections
were
below
0.1
ppb.
The
assessment
also
omits
USGS
data
that
would
reflect
significant
usage
changes
resulting
from
azinphos
methyl
label
changes
in
2002
and
2003.
USGS
data
indicate
that
between
2001
and
2004
in
Washington
state
there
were
408
azinphos
methyl
samples
with
a
maximum
value
of
0.18
ppb
with
only
7
samples
with
concentrations
above
0.05
ppb."

EFED
Response:
EFED
agrees
that
azinphos
methyl
was
detected
in
a
large
number
of
samples
at
relatively
low
concentrations.
EPA
did
not
re­
evaluate
all
available
monitoring
data
for
this
assessment;
however,
monitoring
data
evaluated
for
one
site,
Granger
Drain,
indicated
a
similar
trend,
with
a
high
percentage
of
azinphos
methyl
detections
at
low
concentrations
during
the
application
season
(
May
20­
August
31).
The
maximum
concentration,
0.18
µ
g/
L,
was
reported
in
2003.
Samples
were
collected
at
most
on
a
weekly
basis.
There
was
no
discernable
trend
in
concentrations
at
that
site
to
correlate
with
a
decline
in
azinphos
methyl
usage
referred
to
in
the
comment.
In
approximately
weekly
sampling
from
1999
to
2004
(
except
2000),
detection
frequency
ranged
from
76%
in
2003
to
100%
in
2001
and
2002.
Only
two
samples
were
collected
during
the
application
season
in
2000.
There
were
also
no
apparent
trends
in
concentration
during
the
application
season
as
well.
Monitoring
in
the
NAWQA
program
for
the
most
part
reflects
larger
streams
and
rivers
that
reflect
a
wide
variety
of
land
uses
in
the
basin.
Smaller
water
bodies
will
have
higher
aquatic
exposures
of
azinphos
methyl.
11
4.
Comment
(
Page
2):
"
The
weight
of
the
evidence
from
available
monitoring
data
indicates
that
azinphos
methyl
concentrations
are
significantly
lower
than
the
hypothetical
values
used
in
the
ecological
risk
model
to
calculate
ecological
impacts
from
azinphos
methyl.
Additionally,
the
monitoring
data
indicate
that
these
values
have
continued
to
decline
as
EPA
has
imposed
greater
restrictions
on
azinphos
methyl
use.
These
factors
are
strong
indicators
that
EPA's
model
overestimates
the
ecological
risk,
since
real
measurements
of
azinphos
methyl
are
significantly
lower
than
the
hypothetical
values
used
in
the
model."

EFED
Response:
A
cursory
analysis
of
the
monitoring
data
from
Washington
did
not
support
the
claim
that
concentrations
in
surface
waters
have
declined
in
all
areas,
although
that
may
be
the
case
in
areas
where
agriculture
is
dominated
by
crops
on
which
azinphos
methyl
can
no
longer
be
used
(
e.
g.
sugar
cane).
EFED
believes
that
the
monitoring
data
do
not
reflect
the
full
potential
for
toxic
exposures
to
azinphos
methyl
as
discussed
above
(
in
the
response
to
comment
#
1
from
Bayer
CropScience).
Available
monitoring
data
are
collected
at
most
on
a
weekly
basis
and
would
be
expected
to
result
in
lower
concentrations
than
are
estimated
by
the
1­
day
modeling
time­
step.
EFED's
Tier­
2
simulation
modeling
is
conservative
by
design
and
estimates
risk
for
locations
that
are
most
vulnerable
to
ecological
risk.
The
concentrations
to
which
aquatic
organisms
are
actually
exposed
probably
fall
somewhere
between
the
monitored
and
modeled
results.
Since
there
continues
to
be
some
monitoring
measurements
above
the
level
of
concern,
based
on
these
results
alone,
we
would
expect
there
to
be
some
adverse
environmental
impacts
as
a
result
of
azinphos
methyl
use.

5.
Comment
(
Page
2):
" 
the
absence
of
recent
adverse
ecological
incidences
indicates
that
previous
label
modifications
have
been
effective
in
reducing
the
ecological
impact
of
azinphos
methyl
use.
The
dearth
of
such
incidents
also
suggests
that
EPA's
theoretical
risk
model
overstates
the
real
risk
from
azinphos
methyl
use.
As
an
example,
most
previous
incidents
were
caused
by
uses
on
cotton
or
sugarcane
which
are
no
longer
labeled
for
use.
Additionally,
there
have
been
no
reported
incidents
since
2001."

EFED
Response:
Cancellation
of
the
use
of
azinphos
methyl
on
both
sugar
cane
and
cotton,
in
particular,
undoubtedly
reduced
the
ecological
risks
associated
with
this
chemical.
However,
the
risks
associated
with
the
remaining
uses
of
azinphos
methyl
are
still
very
high.
Our
assessment
concluded
that
there
are
acute
and
chronic
risks
to
all
aquatic
and
terrestrial
animals
for
all
of
the
remaining
labeled
uses.

Further,
the
trend
of
decreasing
adverse
ecological
incidents
in
the
EIIS
database
is
not
unique
to
azinphos
methyl.
Reports
of
adverse
ecological
incidents
have
dropped
dramatically
since
1995.
We
suspect
that
this
decline
is
more
of
a
result
of
reduced
reporting
rather
than
to
a
drastic
decrease
in
pesticide
risk
to
fish
and
wildlife.
In
recent
years,
state
budget
shortfalls
have
caused
many
states
have
cut
funding
for
programs
responsible
for
investigating
and
reporting
fish
and
wildlife
mortality
incidents.
12
Citations
Balcomb
R,
Stevens
R,
Bowen
II
C.
1984.
Toxicity
of
16
granular
insecticides
to
wildcaught
songbirds.
Bull.
Environ.
Contam.
Toxicol.
33:
302­
307.

Madrigal
JL,
Pixton
GC,
Collings
BJ,
Booth
GM,
Smith
HD.
1996.
A
comparison
of
two
methods
of
estimating
bird
mortalities
from
field­
applied
pesticides.
Env.
Tox.
Chem.
15:
878­
885.

USDA
NRCS.
2000.
Conservation
Buffers
for
Reducing
Pesticide
Losses.
Natural
Resource
Conservation
Service.
Fort
Worth,
TX.
21
pp.
