UNITED
STATES
ENVIRONMENTAL
PROTECTION
AGENCY
WASHINGTON,
D.
C.
20460
OFFICE
OF
PREVENTION,
PESTICIDES
AND
TOXIC
SUBSTANCES
MEMORANDUM
March
25,
2002
SUBJECT:
Corrected
version
of
EFED's
eco
portion
of
SRRD's
April
2001
Disulfoton
IRED
FROM:
Henry
Craven,
Biologist,
ERB
3,
EFED
(7507C)

THRU:
Kevin
Costello,
Acting
Branch
Chief
ERB
3,
EFED
(7507C)

TO:
Betty
Shackleford,
PM
53
Christina
Scheltema,
PM
Team
Reviewer
Michael
Goodis
Reregistration
Branch
3
Special
Review
and
Reregistration
Division
(7508W)

This
memo
serves
to
transmit
the
corrected
version
of
EFED's
8/
20/
01
modification
of
EFED's
Eco
portion
of
SRRD's
April
2001
Disulfoton
IRED.
Included
is
the
output
files
for
a
number
of
runs
of
the
terrestrial
exposure
model­­
FATE5.
2
B.
Environmental
Risk
Assessment
A
summary
of
the
Agency's
environmental
risk
assessment
is
presented
below.
For
detailed
discussions
of
all
aspects
of
the
environmental
risk
assessment,
see
the
document,
Preregistration
Eligibility
Decision
for
Disulfoton,
dated
January
13,
2000,
available
in
the
public
docket
and
the
most
recent
amendment
to
this
document,
dated
September
5,
2000.

The
environmental
risk
assessment
for
disulfoton
has
been
refined
with
new
information
submitted
during
phases
3
and
5
of
the
public
participation
process.
This
information
included
proposed
changes
to
the
disulfoton
registration,
such
as
reductions
in
the
rate
and
frequency
of
application,
to
mitigate
risks,
as
well
as
public
comments
on
environmental
risk
and
drinking
water.
1.
Environmental
Fate
and
Transport
In
soil,
disulfoton
is
not
expected
to
undergo
significant
hydrolysis
or
volatilization.
Disulfoton
parent
is
photochemically
degraded
rapidly
by
sunlight
on
soil
and
in
water
where
light
can
penetrate.
Disulfoton
is
metabolized
or
oxidized
in
soil
to
the
corresponding
sulfoxide
and
sulfone
degradates.
Degradation
of
disulfoton
parent
in
soil
does
not
appear
to
follow
firstorder
kinetics,
but
the
half
life
is
less
than
6
days.
Field
dissipation
studies
confirm
that
disulfoton
does
not
persist
in
the
environment.
EPA
does
not
have
data
on
the
anaerobic
metabolism
of
disulfoton.
Disulfoton
is
not
considered
mobile
under
convective­
dispersive
processes,
but
it
has
been
detected
in
groundwater
monitoring
conducted
in
highly
vulnerable
areas.

Disulfoton
degrades
in
the
environment.
The
major
degradates,
disulfoton
sulfone
and
sulfoxide,
are
more
persistent
and
mobile
than
the
parent.
As
much
as
35%
of
the
applied
disulfoton
remained
in
soil
as
disulfoton
sulfone
after
367
days.
Thus
the
degradates
appear
to
be
much
more
persistent
than
parent
in
soil.
The
other
degradates
were
either
not
identified
or
occurred
at
much
lower
concentrations.
However,
the
Agency
is
concerned
that
the
sulfoxide
and
sulfone
degradates
have
a
high
potential
to
reach
ground
and
surface
water.
In
field
testing,
degradates
were
detected
at
a
depth
of
18
inches,
indicating
potential
mobility.
The
Agency
has
limited
data
regarding
the
persistence
of
the
degradates
and
lacks
the
absorption/
desorption
data
necessary
to
confirm
the
mobility
of
the
degradates.
Aerobic
and
anaerobic
aquatic
metabolism
studies
are
required
for
the
parent
and
degradates.
A
study
on
the
mobility
and
leaching
potential
of
the
degradates
is
also
required.

2.
Water
Resources
Assessment
The
water
resources
assessment
is
summarized
earlier
in
this
document.
The
surface
water
EECs
shown
in
Table
­
were
used
to
assess
potential
drinking
water
exposure
to
disulfoton.
The
drinking
water
assessment
has
been
refined
to
include
the
percent
crop
area
3
factor
and
the
index
reservoir.
However,
the
ecological
water
resources
assessment
does
not
include
the
refinements
mentioned
above.
The
Agency's
current
policy
is
to
include
these
refinements
in
the
drinking
water
assessment
but
not
in
the
ecological
risk
assessment
because
the
"
unrefined"
farm
pond
on
the
edge
of
field
scenario
is
thought
to
better
represent
the
conditions
for
ecological
exposure.
For
more
information,
see
Preregistration
Eligibility
Document
for
Disulfoton,
September
5,
2000.

3.
Ecological
Risk
Assessment
The
Agency's
ecological
risk
assessment
compares
toxicity
endpoints
from
ecological
toxicity
studies
to
estimated
environmental
concentrations
based
on
environmental
fate
characteristics,
pesticide
use,
and/
or
monitoring
data.
The
Agency
first
assesses
the
acute
and
chronic
toxicity
to
each
of
four
groups
of
nontarget
animals.
Acute
toxicity
is
expressed
as
follows:

­EC50
(
invertebrates),
­LC50
(fish
and
birds),
and
­LD50
(birds
and
mammals)

Chronic
toxicity
is
expressed
as
follows:

­NOAEL
or
NOAEC
for
avian
and
mammal
reproduction
studies,
and
either
­The
NOAEL
for
chronic
aquatic
studies,
or
­The
Maximum
Allowable
Toxicant
Concentration
(MATC).
To
estimate
potential
ecological
risk,
EPA
integrates
the
results
of
exposure
and
ecological
toxicity
studies
using
the
quotient
method.
Risk
quotients
(RQs)
are
calculated
by
dividing
exposure
estimates
by
ecological
toxicity
values,
both
acute
and
chronic,
for
various
species.
These
RQ
values
are
compared
to
levels
of
concern
(LOCs),
which
provide
an
indication
of
the
relative
risk
the
particular
pesticide
and/
or
use
may
pose
for
nontarget
organisms.
In
general,
the
higher
the
RQ
the
greater
the
concern.
The
LOC
indicates
whether
a
chemical,
when
used
as
directed,
has
the
potential
to
cause
undesirable
effects
on
nontarget
organisms.
When
the
risk
quotient
exceeds
the
LOC
for
a
particular
category,
the
Agency
presumes
a
risk
of
concern
to
that
category.
The
LOC's
and
the
corresponding
Risk
presumptions
are
presented
in
the
following
table:

Table
9.
Levels
of
Concern
(LOCs)
and
Associated
Risk
Presumption
IF...
THEN
the
Agency
presumes...

Mammals
and
Birds
The
acute
RQ
>
LOC
of
0.5,
Acute
risk
The
acute
RQ
>LOC
of
0.2,
Risk
that
may
be
mitigated
through
restricted
use
The
acute
RQ
>
LOC
of
0.1,
Acute
effects
may
occur
in
Endangered
species
The
chronic
RQ
>
LOC
of
1
Chronic
risk
and
Chronic
effects
may
occur
in
Endangered
species
IF...
THEN
the
Agency
presumes...

4
Fish
and
Aquatic
Invertebrates
The
acute
RQ
>
LOC
of
0.5
Acute
risk
The
acute
RQ
>
LOC
of
0.1
Risk
that
may
be
mitigated
through
restricted
use
The
acute
RQ
>LOC
of
0.05
Acute
effects
may
occur
in
Endangered
species
The
chronic
RQ
>
LOC
of
1
Chronic
risk
and
Chronic
effects
may
occur
in
Endangered
species
Plants
The
RQ
>
LOC
of
1
Acute
risk
The
RQ
>
LOC
of
1
Endangered
plants
may
be
affected
No
separate
criteria
exist
for
restricted
use
or
chronic
effects
for
plants.

Risk
characterization
provides
further
information
on
the
likelihood
of
adverse
effects
occurring
by
considering
the
use
pattern
of
the
pesticide;
its
fate
in
the
environment;
the
species
and
populations
of
organisms
potentially
at
risk,
their
spatial
and
temporal
distributions;
and
the
nature
of
the
effects
observed
in
toxicity
studies.

a.
Toxicity
of
Disulfoton
to
non
target
organisms
The
Agency
has
a
fairly
robust
toxicity
database
for
disulfoton
and
the
two
primary
degradates,
disulfoton
sulfoxide
and
disulfoton
sulfone.
The
following
table
contains
the
toxicity
values
used
in
the
terrestrial
animal
risk
assessment
Table
7.
Toxicity
endpoints
used
in
assessing
risk
of
terrestrial
organisms
for
disulfoton
Species
Test
Type
Results
(ppm
ai)
Toxicity
Classification
Source
of
Data
Japanese
quail
sub
acute
dietary
LC50=
333
highly
toxic
0034769
Northern
bobwhite
quail
sub
acute
dietary
LC50)
=
544
moderately
toxic
0094233
Northern
bobwhite
quail
sub
acute
dietary
LC50
(sulfone
metabolite)
=
558
moderately
toxic
42585106
Northern
bobwhite
quail
sub
acute
dietary
LC50
(sulfoxide
metabolite)
=
456
highly
toxic
42585105
Mallard
duck
acute
oral
LD50=
6.54
mg
ai/
kg
very
highly
toxic
00160000
Mallard
duck
reproduction
NOAEC=
37
LOAEC=
80
(decreased
adult
and
hatchling
body
weight)
N/
A
43032502
Species
Test
Type
Results
(ppm
ai)
Toxicity
Classification
Source
of
Data
5
Laboratory
rat
acute
oral
LD50=
1.9
mg
ai/
kg
very
highly
toxic
072293
Laboratory
rat
acute
oral
LD50
(sulfone
metabolite)
=11.24
mg
/kg
highly
toxic
0071873
Laboratory
rat
acute
dietary
1­
day
LC50
1
(2
to
12.7ppm)
highly
to
very
highly
toxic
N/
A
Laboratory
rat
2­
generation
reproduction
NOAEL=
0.8
LOAEL=
2.4
(decreased
litter
size
and
pup
survival)
N/
A
261990
Honey
bee
acute
contact
LD50
=
4.1
ug
ai/
bee
moderately
toxic
05004151
Honey
bee
acute
contact
LD50
(sulfone
metabolite)
=
0.96
ug/
bee
highly
toxic
42582902
Honey
bee
acute
contact
LD50
(sulfoxide
metabolite)
=
1.11
ug
/bee
highly
toxic
42582901
Honey
bee
acute
foliar
residue
2
RT25
(8
EC)
<
3hrs
at
1.0
lb
ai/
A
N/
A
0163423
1
one­
day
LC50
=
LD50
(mg/
kg)
/
proportion
of
body
weight
consumed.
The
mammalian
LD50
of
1.9
mg/
kg
was
used
to
estimate
1­
day
LC50s
ranging
from
2
ppm
for
a
15
gram
herbivore
(consumes
95%)
to
12.7
ppm
for
a
1000
gram
granivore
(consumes
15%)
2
RT25
(residual
time)
time
required
to
reduce
mortality
of
caged
bees
to
field
weathered
spray
deposits.
6
Table
8.
Toxicity
endpoints
used
in
assessing
risk
of
aquatic
organisms
for
disulfoton
Freshwater
Species*
Test
Type
Results
(ppb
ai)
Toxicity
Category
Source
of
Data
Bluegill
Acute
LC50=
39
very
highly
toxic
00068268
Bluegill
Acute
LC50
(sulfone
metabolite)
=112
highly
toxic
42585108
Bluegill
Acute
LC50
(sulfoxide
metabolite)
=188
highly
toxic
42585107
Bluegill
Early
Life
Stage**
estimated
NOAEC
=
4.6
Extrapolated
from
41935801
Glass
shrimp
Acute
EC50=
3.9
Very
highly
toxic
40094602
Water
flea
Life
Cycle
NOAEC=
0.037
N/
A
41935802
Water
flea
Life
Cycle
NOAEC
(sulfone
metabolite)
=0.14
N/
A
43738001
Water
flea
Life
Cycle
NOAEC
(sulfoxide
metabolite)
=
1.53
N/
A
43738002
Marine
Species*

Sheepshead
minnow
Acute
LC50=
520
highly
toxic
40228401
Sheepshead
minnow
Acute
LC50
(sulfone
metabolite)
=
1060
moderately
toxic
44369901
Sheepshead
minnow
Acute
LC50
(sulfone
metabolite)
=
11300
slightly
toxic
44369902
Sheepshead
minnow
Early
Life
Stage
NOAEC=
16.2
N/
A
42629001
Sheepshead
minnow
Full
Life
Cycle
EC05=
0.96***
N/
A
43960501
Eastern
Oyster
Acute
EC50=
720
highly
toxic
40228401
Brown
shrimp
Acute
EC50=
15
very
highly
toxic
40228401
Mysid
Life
Cycle
EC05=
2.35***
N/
A
43610901
*
The
species
listed
and
used
in
risk
assessment
were
selected
from
the
toxicity
data
because
they
seemed
to
represent
a
distribution
of
sensitivity.
**
An
early
life
stage
study
was
not
conducted
with
bluegill,
but
was
derived
from
a
rainbow
trout
study
(MRID
41935801).
7
b.
Environmental
Exposure
to
Disulfoton
EPA
uses
models
to
estimate
exposure
of
nontarget
plants
and
animals
to
disulfoton.
For
terrestrial
birds
and
mammals,
the
Agency
first
estimates
initial
levels
of
Disulfoton
residues
on
various
food
items
consumed
by
wildlife
using
the
Fletcher
nomogram(
MRID
#
(45374901)
followed
by
a
first
order
decline
model
such
as
FATE5.
This
assessment
was
further
characterized
after
reviewing
one
residue
monitoring
study
conducted
in
potatoes..
Based
on
the
results
of
this
study
a
foliar
dissipation
half
life
of
3.3
was
derived
and
was
subsequently
used
to
estimate
terrestrial
exposure
using
the
FATE5
model.

The
following
table
shows
predicted
residues
immediately
after
application
on
terrestrial
food
items
that
result
from
a
single
application
of
disulfoton
calculated
from
Hoerger
and
Kenaga
(1972)
as
modified
by
Fletcher
et
al.
(1994):

Table
9:
Estimated
Environmental
Concentrations
on
Avian
and
Mammalian
Food
Items
(ppm)
Following
a
Single
Application
at
1
lb
ai/
A
Food
Items
EEC
(ppm)
Predicted
Maximum
Residue
EEC
(ppm)
Predicted
Mean
Residue
Short
grass
240
85
Tall
grass
110
36
Forage
and
small
insects
135
45
Fruits,
pods,
seeds,
and
large
insects
15
7
These
residues
served
as
the
initial
concentrations
from
which
first­
order
residue
declines
were
calculated.
When
considering
repeat
applications,
degradation
over
time
is
simulated
from
the
first
application
to
a
period
following
the
last
application.
The
time
period
modeled
varies,
depending
on
the
number
of
applications,
the
interval
between
applications.
However
30
days
was
usually
modeled
unless
otherwise
specified.
The
FATE5
program
generates
a
peak
value
as
well
as
a
time­
weighted
average
value
for
the
time
period
modeled.
The
Fletcher
peak
maximum
value
for
the
food
item
was
compared
to
the
acute
toxicity
value
to
produce
the
acute
Risk
Quotient
(RQ).
For
chronic
risk,
the
Fletcher
maximum
value
was
used
as
the
initial
input.
Both
the
peak
maximum
for
short
grass
and
time­
weighted
average
maximum
EECs
for
short
grass
and
other
food
items
were
used
to
compute
chronic
RQs.

For
aquatic
organisms,
EPA
estimates
the
concentration
of
parent
disulfoton
in
surface
water
using
the
Tier
II
PRZM/
EXAMs
models.

4.
Nontarget
Terrestrial
Animal
Risk
a.
Risk
to
Birds
and
Mammals
EPA
predicts
acute
risk
to
birds
and
mammals
for
both
the
granular
(15
%
ai)
and
liquid
8
EC
(8
%
ai)
formulations.
RQs
for
birds
and
mammals
are
summarized
in
Tables
10
thru
12
below.
Bird
kills
have
been
associated
with
applications
of
granular
disulfoton
to
a
tree
nursery
and
potatoes.
Field
studies
in
potatoes
and
small
grains
showed
small
mammals
to
be
sensitive
to
the
15%
granular
product
and
jackrabbits
to
be
sensitive
to
the
liquid
products.
Also,
EPA
has
received
a
poisoning
report
of
Swainson
hawks
that
died
following
ingestion
of
disulfoton
contaminated
grasshoppers.
The
Agency
predicts
chronic
risk
to
birds
and
mammals
from
liquid
disulfoton
(8
EC);
mammals
appear
to
be
at
greater
risk
than
birds.

Table
10.
Summary
of
Acute
Ecological
Risks
to
Birds
and
Mammals
potentially
exposed
to
Di­
Syston
8EC
(liquid)
in
food.
Use
Scenario
Risk
Quotients
(RQs)

Crop
Application
Rate/
Method/
Site
(foliar
or
soil)
Number
of
Applications
per
Season
Time
Interval
between
Applications
Birds
1
LC50
=333
ppm
Mammals
2
Estimated
1
day
LC50
=
2­
12.7
ppm
Tobacco
4
lbs
ai/
A
aerial
(soil),
unincorporated
1
N/
A
0.2­
2.8
Adjacent
to
field
0.9­
480
Adjacent
to
field
4
lbs
ai/
A
ground
(soil),
broadcast,
incorporated
1
N/
A
0.2­
1.6
Within
field
granivore
&
insectivore
0.9­
270
Within
field,
granivore
insectivore
Potatoes
NW
only
3
lb
ai/
A
ground
(foliar),
chemigation
1
N\
A
0.1­
2.2
0.
7­
360
Potatoes
3
lb
ai/
A
ground
(soil),
unincorporated
side
dress
1
N/
A
approx
0.1­
2.2
Slightly
less
than
foliar
approx
0.7­
360
Slightly
less
than
foliar
3
lb
ai/
A
ground
(soil),
broadcast,
incorporated
1
N/
A
0.1­
1.2
Within
field
granivore
&
insectivore
0.7­
202
Within
field,
granivore
insectivore
3
lb
ai/
A
ground
(soil),
in
furrow
or
injection
1
N/
A
risk
can
not
be
quantified,
but
less
than
surface
application
risk
can
not
be
quantified,
but
less
than
surface
application
Peas
&
Lentils
2.5
lbs
ai/
A
ground
(soil)
injection
or
in
furrow
1
N/
A
risk
can
not
be
quantified,
but
less
than
surface
application
risk
can
not
be
quantified,
but
less
than
surface
application
Chili
peppers
2
lbs
ai/
A
ground
(soil),
broadcast,
incorporated
1
N/
A
0.1­
0.8
Within
field
granivore
&
insectivore
0.5­
135
Within
field
granivore
&
insectivore
Use
Scenario
Risk
Quotients
(RQs)

Crop
Application
Rate/
Method/
Site
(foliar
or
soil)
Number
of
Applications
per
Season
Time
Interval
between
Applications
Birds
1
LC50
=333
ppm
Mammals
2
Estimated
1
day
LC50
=
2­
12.7
ppm
9
Beans
(snap,
dry
&
lima),
lettuce,
cabbage
2
lbs
ai/
A
ground
(soil),
injection
1
N/
A
risk
can
not
be
quantified,
but
less
than
surface
application
risk
can
not
be
quantified,
but
less
than
surface
application
Cotton,
sorghum
Broccoli,
Wheat,
cauliflower,
brussels
sprouts,
cabbage,
barley
1
lbs
ai/
A
ground
(soil),
injection
1
N/
A
risk
can
not
be
quantified,
but
less
than
surface
application
risk
can
not
be
quantified,
but
less
than
surface
application
Wheat
0.75
lb
ai/
A
aerial
(foliar)
1
0.
03­
0.5
0.2­
90
Poplars
for
pulp
wood
3
lb
ai/
A
ground
(soil),
unincorporated
3
21
day
interval
0.1­
2.2
0.
7­
364
Asparagus
1
lb
ai/
A
ground
and
or
aerial
(foliar)
3
assumed
21
day
interval
0.05­
0.7
0.
2­
121
Barley
1
lb
ai/
A
ground
and
or
aerial
foliar
2
21
day
interval
0.05­
0.7
0.
2­
121
Potato
(East
of
Rockies
only),
brussels
sprouts,
cauliflower
0.5
lb
ai/
A
aerial
or
ground
(foliar)
3
14
days
0.02­
0.4
Ground
less
risk
than
aerial
0.13­
63
Ground
less
risk
than
aerial
Sorghum
0.5
lb
ai/
A
aerial
(foliar)
2
14
days
0.02­
0.4
0.
1­
63
3
days
0.03­
0.5
0.
2­
92
Cotton
(SLN)
TX
0.2
lb
ai/
A
aerial
(foliar)
2
21
days
0.01­
0.15
0.05­
24
1
RQs
for
birds
vary
according
to
food
items
consumed;
the
range
is
presented
here.
2
RQs
for
mammals
vary
according
to
body
weight
and
food
items
consumed;
the
range
is
presented
here.
Additional
information
can
be
found
in
the
September
5,
2000,
revised
environmental
risk
assessment.
10
Table
11.
Summary
of
Chronic
Ecological
Risks
to
Birds
and
Mammals
potentially
exposed
to
Di­
Syston
8EC
(liquid)
in
food.
Unless
specified
otherwise
the
RQ
is
based
on
a
a
3.3
day
half
life
and
30
day
average
maximum
residue
values.
RQ
in
(
)
is
based
on
peak
maximum
residues
short
grass.
Use
Scenario
Risk
Quotients
(RQs)

Crop
Application
Rate/
Method/
Site
(foliar
or
soil)
Number
of
Applications
per
Season
Time
Interval
between
Applications
Birds
1
NOAEC
=
37
ppm
Mammals
2
NOAEC
=
0.8
ppm
Tobacco
4
lbs
ai/
A
aerial
(soil),
unincorporated
1
N/
A
0.3­
4.5
(26)
13­
210
(1200)

4
lbs
ai/
A
ground
(soil),
broadcast,
incorporated
1
N/
A
0.3­
2.5
(14)
Within
field
granivore
&
insectivore
13­
118
(675)
Within
field,
granivore
insectivore
Potatoes
NW
only
3
lb
ai/
A
ground
(foliar),
chemigation
1
N\
A
0.2­
3.4
(19)
9.8­
158
(900)

Potatoes
3
lb
ai/
A
ground
(soil),
unincorporated
side
dress
1
N/
A
approx
0.2­
3.4
(19)
Slightly
less
than
foliar
approx
9.8­
158
(900)
Slightly
less
than
foliar
3
lb
ai/
A
ground
(soil),
broadcast,
incorporated
1
N/
A
0.2­
1.9
(11)
Within
field
granivore
&
insectivore
9.8­
89
(506)
Within
field,
granivore
insectivore
3
lb
ai/
A
ground
(soil),
in
furrow
or
injection
1
N/
A
risk
can
not
be
quantified,
but
less
than
surface
application
risk
can
not
be
quantified,
but
less
than
surface
application
Peas
&
Lentils
2.5
lbs
ai/
A
ground
(soil)
injection
or
in
furrow
1
N/
A
risk
can
not
be
quantified,
but
less
than
surface
application
risk
can
not
be
quantified,
but
less
than
surface
application
Chili
peppers
2
lbs
ai/
A
ground
(soil),
broadcast,
incorporated
1
N/
A
0.1­
1.3
(7.3)
Within
field
granivore
&
insectivore
6.6­
59
(337)
Within
field
granivore
&
insectivore
Beans
(snap,
dry
&
lima),
lettuce,
cabbage
2
lbs
ai/
A
ground
(soil),
injection
1
N/
A
risk
can
not
be
quantified,
but
less
than
surface
application
risk
can
not
be
quantified,
but
less
than
surface
application
Use
Scenario
Risk
Quotients
(RQs)

Crop
Application
Rate/
Method/
Site
(foliar
or
soil)
Number
of
Applications
per
Season
Time
Interval
between
Applications
Birds
1
NOAEC
=
37
ppm
Mammals
2
NOAEC
=
0.8
ppm
11
Cotton,
sorghum
Broccoli,
Wheat,
cauliflower,
brussels
sprouts,
cabbage,
barley
1
lb
ai/
A
ground
(soil),
injection
1
N/
A
risk
can
not
be
quantified,
but
less
than
surface
application
risk
can
not
be
quantified,
but
less
than
surface
application
Wheat
0.75
lb
ai/
A
aerial
(foliar)
1
N/
A
0.05­
0.85
(4.9)
2.5­
40
(225)

Poplars
for
pulp
wood
3
lb
ai/
A
ground
(soil),
unincorporated
3
21
day
interval
0.3­
4.9
(20)
63
day
ave.
14­
225
(911)
63
day
ave
Asparagus
1
lb
ai/
A
ground
and
or
aerial
(foliar)
3
assumed
21
day
interval
0.1­
1.6
(6.6)
Ground
less
risk
than
aerial
63
day
ave.
4.7­
75
(304)
Ground
less
risk
than
aerial
63
day
ave.

Barley
1
lb
ai/
A
ground
and
or
aerial
(foliar)
2
21
day
interval
0.1­
1.6
(6.6)
Ground
less
risk
than
aerial
42
day
ave
4.7­
75
(304)
Ground
less
risk
than
aerial
42
day
ave
Potato
(East
of
Rockies
only),
brussels
sprouts,
cauliflower
0.5
lb
ai/
A
ground
or
aerial
(foliar)
3
14
days
0.08­
1.2
(3)
Ground
less
risk
than
aerial
42
day
ave
3.5­
56
(158)
Ground
less
risk
than
aerial
42
day
ave
Sorghum
0.5
lb
ai/
A
aerial
(foliar)
2
14
days
0.07­
1.1
(3)
3.
2­
52
(158)

3
days
0.2­
3
(5)
9
day
ave
8.6­
138
(230)
9
day
ave
Cotton
(SLN)
TX
0.2
lb
ai/
A
aerial
(foliar)
2
21
days
0.02­
0.3
(1)
42
day
ave
0.9­
15
(61)
42
day
ave
1
RQs
for
birds
vary
according
to
food
items
consumed;
the
range
is
presented
here.
2
RQs
for
mammals
vary
according
to
body
weight
and
food
items
consumed;
the
range
is
presented
here.
Additional
information
can
be
found
in
the
September
5,
2000,
revised
environmental
risk
assessment.

The
Agency's
assessment
suggests
the
potential
for
the
8
EC
formulation
(liquid)
to
cause
acute
effects
to
non
endangered
herbivorous
birds
from
a
single
aerial
application
at
or
above
0.75
lb
ai/
A.
Endangered
granivores
would
be
at
risk
from
a
single,
2.0
lb
ai/
A
soil
incorporated
application.
The
avian
acute
RQs
range
from
less
than
0.1
for
potatoes
at
3.0
lbs
ai/
ai
when
applied
in
furrow
or
soil
injected
to
2.8
on
short
grass
from
a
single,
4
lb
ai/
A
aerial
application
12
to
tobacco.
For
the
same
use
patterns/
food
items,
mammalian
acute
RQs
range
from
less
than
0.1
to
480.
A
comparison
of
the
NOAECs
from
avian
reproduction
studies
to
estimated
exposure
concentrations
from
uses
other
than
in
furrow
or
soil
injection,
produced
chronic
RQs
ranging
from
0.02
for
cotton
(the
42­
day
average
on
seeds
for
2
aerial
applications
with
21
day
intervals
at
0.2
lbs
ai/
A)
to
26
for
tobacco
(the
peak
on
short
grass
for
a
single
aerial
applications
at
4.0
lbs
ai/
A).
For
the
same
use
patterns,
when
the
NOAEL
in
the
2­
generation
rat
study
is
used
as
an
endpoint,
the
chronic
RQs
range
from
0.9
to
1200.
For
both
birds
and
mammals,
most
of
the
RQs
are
above
the
Agency's
level
of
concern
for
chronic
effects.
These
exceedences
last
for
several
weeks.
In
all
cases
(except
for
in
furrow
or
soil
injection)
for
mammal,
but
only
in
a
few
uses
for
birds,
not
only
the
peak
residues,
but
also
the
time
weighted
average
residues
exceed
the
test
levels
at
which
chronic
effects
were
observed
(LOAECs).

Registrants
have
expressed
concern
regarding
the
Agency's
use
of
Fletcher
values
and
models
such
as
FATE5
in
its
preliminary
exposure
assessment.
Two
field
residue
monitoring
studies
submitted
by
a
registrant
were
pertinent
to
current
uses
of
disulfoton
on
potatoes.
In
the
study
(MRID
#412018­
01),
Di­
Syston
8
was
aerially
applied
to
potato
foliage
3
times
(6
to
10
day
intervals)
at
1
lb
ai/
acre
in
Michigan.
Residues
on
the
potato
leaves
peaked
at
105
ppm
after
the
2
nd
application
and
had
a
mean
value
of
41
ppm
over
the
course
of
the
study.
These
values
are
reasonably
close
to
the
FATE5
model
(scenario
was
1
lb
ai/
A,
3
applications,
10
day
interval,
21
day
sampling
period,
and
half
life
3.3
days)
estimate
of
residues
on
broadleaves
of
153
ppm
(peak)
and
51ppm
(mean).
A
second
residue
monitoring
study
(MRID
#411189­
01)
in
Michigan
was
performed,
in
which
Di­
Syston
8
was
soil
incorporated
by
ground
equipment,
(initially
in
furrow
at
planting
at
3
lb
ai/
acre
and
6
­
7
weeks
later
as
a
side
dressing
at
3
lbs
ai/
acre).
As
was
expected
the
residues
on
potato
foliage
were
lower
(peak
was
44
ppm
and
mean
was
8
ppm)
than
in
the
first
study.
Finding
residues
is
due
in
part
because
disulfoton
is
systemic
and
secondly,
though
directed
at
the
soil,
some
spray
would
contact
the
emerged
plants
during
the
second
application.
In
conclusion,
the
foliar
application
study
appears
to
support
the
use
of
the
Fletcher
values
in
a
model
such
as
FATE5
to
predict
residues
on
foliage.

The
acute
and
chronic
RQs
are
based
solely
on
dietary
exposure
via
contaminated
food
sources.
Other
routes
of
exposure,
including
dermal,
inhalation,
and
drinking
from
contaminated
puddles
might
also
be
important
(Driver
et
al.
1991)
and
could
further
increase
acute
risks
if
methods
were
available
to
include
them
in
the
risk
assessment.
Other
factors
contributing
to
uncertainty
(especially
for
chronic
effects)
include
when
exposure
occurs
during
the
reproductive
cycle;
the
duration
of
exposure
required
to
cause
a
physiological
effect
and
sub
lethal
effects
to
adults
that
may
impact
breeding
and
nurturing
behavior.

The
following
table
summarizes
the
acute
risk
to
birds
and
mammals
from
the
use
of
the
granular
formulation
(15
G)
of
disulfoton.
13
Table
12.
Acute
Risk
Estimates
for
Birds
and
Mammals
Exposed
to
Di­
Syston
15G
(Granular).
Based
on
mallard
ago
LD50
(6.54mg/
kg)
and
rat
a.
o.
LD50
(1.9
mg/
kg).
Use
Scenario
RQs
Crop
Application
Rate
lb
ai/
A
and
or
(oz.
ai/
1000
ft)
Application
Method
mg
ai/
ft
2
exposed
on
soil
surface
Birds
Mammals
Christmas
trees
(approx
1700/
A)
78
(0.69
oz
ai/
tree
~
2
ft
2
)
Spot
treatment/
broadcast,
unincorporated
approx
9,780
approx
1,500­
75,200
approx
5,100­
257,300
Christmas
trees
(SLN)
NC
approx
1700/
A
4.5
(0.04
oz
ai
/
tree
~
2
ft
2
)
Spot
treatment/
broadcast,
unincorporated
567
approx
85­
4,350
approx
300­
14900
Tobacco
4
(6)
Banded
(assume
6
inches),
incorporated
51
7­
392
26­
1342
Banded
(assume
12
inches),
incorporated
25.5
3.
5­
196
13­
671
Broadcast,
incorporated
6.2
0.
9­
48
3­
164
Ornamental
flowers
(gladiolus)
28.6
(1.05
oz/
100
ft
2
)
broadcast,
incorporated
45
6.8­
346
24­
1184
Ornamental
flowers
(gladiolus)
4.5(
0.16
oz/
100
ft
2
)
broadcast,
incorporated
7
1­
54
3.
6­
184
Ornamental
flowers
(gladiolus)
6
(11.25)
banded–
in
trench,
incorporated
assumed
zero
assumed
zero
assumed
zero
Potatoes
3
(3.4)
Banded
(assume
6
inches)
incorporated
28.9
4.
5­
225
15­
772
Broadcast,
incorporated
4.7
0.
7­
35
2.
5­
123
In
furrow,
incorporated
1.9
0.
3­
15
1­
51
Peas
and
Lentils
2.5
Broadcast,
unincorporated
26
3.8­
198
13­
683
Peppers
2
(2)
Banded
(assume
6
inches),
incorporated
17
2.5­
130
9­
447
Soy
beans
1
(1.2)
Banded
(
4
inch),
incorporated
17
2.5­
130
9­
447
Cabbage
1.5
(1.7)
Banded
(assume
6
inches),
incorporated
14.4
2.
2­
110
7.5­
378
Sorghum
1
1
Broadcast
to
whorls
10.4
1.5­
80
5­
270
Use
Scenario
RQs
Crop
Application
Rate
lb
ai/
A
and
or
(oz.
ai/
1000
ft)
Application
Method
mg
ai/
ft
2
exposed
on
soil
surface
Birds
Mammals
14
Barley,
wheat
1
Broadcast,
unincorporated
10.4
1.
5­
80
5­
270
Drilled
approx
0.1
approx
<0.1­
0.8
approx
<0.1­
2.7
Clover
1
(for
seed)
SLN
1
Broadcast
to
foliage,
unincorporated
10.4
1.
5­
80
5­
270
Cotton,
sorghum
1
(1.2)
Banded
(assume
6
inches),
incorporated
10.2
1.
5­
80
5­
270
Peanuts,
cole
crops,
1
(1.1)
Banded
(assume
6
inches),
incorporated
9.3
1.
4
­70
5­
240
Beans
(Lima,
Dry)
1
(0.9)
Banded
(6inch),
incorporated
7.6
1.
1­
70
4­
200
Ornamental
trees
(Holly,
birch)
4.5
Broadcast,
incorporated
7.0
1­
54
3.
6­
184
Ornamental
trees
(Holly,
birch)
(12
oz)
In
furrow
6.
8
1­
52
3.5­
178
Cotton,
sorghum
1
(1.2)
In
furrow,
incorporated
0.68
0.1­
5
0.
3­
17
Peanuts
1
(1.1)
In
furrow,
incorporated
0.62
0.1­
5
0.
3­
17
1Some
granules
will
be
retained
in/
on
foliage
and
could
be
ingested
by
non
target
birds
and
mammals.
RQs
for
birds
and
mammals
vary
according
to
body
weight;
the
range
is
presented
here.
Additional
information
can
be
found
in
the
September
5,
2000,
revised
environmental
risk
assessment.

The
Agency's
assessment
suggests
potential
for
the
15
G
formulation
to
cause
acute
risk
to
birds
from
a
single
application
at
or
above
the
lowest
application
rate
of
1.0
lb
ai/
A
even
when
the
material
is
incorporated.
The
avian
acute
RQs
for
small
birds
range
from
5
for
the
in
furrow,
1
lb
ai/
A
rate
on
cotton
to
approximately
75,200
for
78
lb
ai/
A,
unincorporated
spot
treatment
to
Christmas
trees.
For
the
same
use
patterns/
food
items,
small
mammal
acute
RQs
range
from
17
to
257,300.
EPA
can
not
estimate
long
term
exposure
from
granular
applications
because
the
granules
are
not
expected
to
remain
in
tact
over
extended
periods.
The
chemical
is
expected
to
become
distributed
in
the
soil,
as
the
granules
dissipate.
However
even
a
brief
exposure
period
may
be
sufficient
to
cause
chronic
risk
because
disulfoton
is
chronically
toxic
to
birds
and
mammals
at
low
dietary
concentrations.

Risk
to
birds
and
mammals
from
the
use
of
15
G
(SLN)
on
Christmas
tree
farms
in
North
15
Carolina
Christmas
tree
farms
and
the
adjacent
areas
­­
forests
and
or
pasture
–
provide
excellent
habitat
for
a
great
variety
of
wild
life.
The
North
Carolina
Christmas
Tree
community
has
submitted
numerous
testimonials
emphasizing
the
ever
increasing
numbers
and
diversity
of
wild
life
.
This
includes
game
animals
such
as
turkey
rearing
young
amidst
the
trees,
song
birds,
rodents
and
foxes.
Although
this
information
is
intended
to
suggest
there
is
little
or
no
negative
impact
from
not
only
disulfoton,
but
other
pesticides
or
cultural
practices
as
well,
the
Agency
would
prefer
to
receive
documented
surveys
or
research
before
making
a
final
determination.

b.
Non
target
Insects
Disulfoton
is
moderately
toxic
to
honey
bees
and
its
sulfoxide
and
sulfone
degradates
are
highly
toxic
to
bees.
Although
a
24
hour
residual
study
on
the
8
EC
indicated
no
toxicity
to
honey
bees
following
exposure
to
alfalfa
that
had
been
treated
3
hours
earlier
at
a
rate
of
1.0
lb/
A.,
there
is
uncertainty
as
to
the
risk
from
later
exposure
and
a
longer
period
of
time
to
the
more
toxic
degradates.
Furthermore,
the
risk
from
higher
rates
–
especially
aerial
and
foliar
applications
–
can
not
be
assessed
without
additional
data.

5
Risk
to
Nontarget
Aquatic
Animals
Disulfoton
technical
is
moderately
to
very
highly
toxic
to
freshwater
fish;
very
highly
toxic
to
freshwater
invertebrates;
highly
toxic
to
estuarine
fish
and
highly
to
very
highly
toxic
to
estuarine
invertebrates.
None
of
these
organisms
were
at
risk
from
disulfoton
when
the
EC
was
soil
injected.
Neither
fresh
water
nor
estuarine
fish
acute
risk
Levels
Of
Concern
(LOC)
are
exceeded;
however,
a
few
uses
exceed
restricted
use
and
endangered
species
concerns
for
fresh
water
fish.
Chronic
risk
to
freshwater
and
estuarine
fish
may
occur
from
uses
where
single
application
rates
are
equal
to
4
lb
a.
i./
A.
Estuarine
fish
may
also
be
at
chronic
risk
from
2
or
more
applications
of
the
EC
formulation
at
rates
equal
to
or
greater
than
1
lb
ai/
A.
Although
many
modeled
crop
scenarios
suggest
a
potential
for
acute
risk
for
freshwater
invertebrates;
except
for
the
greater
risk
from
the
tobacco
use,
RQs
were
between
0.5
and
2.1
with
most
being
less
than
one.
Typically,
unless
soil
injection
was
employed,
the
invertebrate
restricted
use
and
endangered
species
concerns
were
exceeded.
Chronic
risk
to
fresh
water
invertebrates
(i.
e.,
number
of
young
produced,
their
survival
and
growth)
is
predicted
for
all
modeled
scenarios.
Although
modeling
predicts
acute
and
chronic
risks
estuarine/
marine
invertebrates
for
a
few
uses
on
such
sites
as
tobacco,
barley
and
cotton,
there
is
uncertainty
in
the
exposure
estimates
and
the
RQs
are
less
then
2
for
acute
and
less
then
6
for
chronic
risk.
RQs
for
fish
and
invertebrates
are
summarized
in
Tables
13
and
14.

(i)
Freshwater
Fish
–
Acute
and
Chronic
Risk
Acute
risk
LOC
is
not
exceeded
for
any
use
patterns.
RQs
range
from
<0.01
(soil
injection
of
the
EC
to
any
crop
or
one
unincorporated
application
of
the
15
G
by
ground
16
equipment
to
soil
at
1.0
lb
ai/
A
to
wheat)
to
0.48
(1
aerial
application
of
4.0
lb
ai/
A
to
soil
for
tobacco).
The
restricted
use
LOC
is
exceeded
by
a
single
application
at
rates
greater
than
or
equal
to1.0
lb
ai/
A..
The
endangered
species
LOC
is
exceeded
by:
1)
a
single,
unincorporated
application
at
rates
greater
than
or
equal
to
0.75
lb
ai/
A
and
2)
2
or
more
unincorporated
applications
at
0.2
lbs
ai/
A.
Chronic
risk
is
only
exceeded
by
one
application
regime
in
tobacco
the
RQ
is
1.5
for
a
single
aerial
application
to
soil
(followed
by
incorporation)
at
4.0
lb
ai/
A.

While
the
acute
LC50
was
never
exceeded
by
peak
concentrations
mortality
is
predicted
for
some
application
regimes
of
the
EC
for
tobacco,
barley
and
possibly
asparagus
(other
than
N.
West).
In
a
series
of
miniature
ponds
known
as
microcosms,
bluegills
were
exposed
to
a
range
of
concentrations
for
27
days.
This
resulted
in
a
27
day
LC10
of
4.7
parts
per
billion.
Since
LC10
is
exceeded
by
the
modeled
21­
day
average
EEC's
(4.5
to
12
ppb)
for
these
3
uses,
this
suggests
use
of
disulfoton
adjacent
to
aquatic
sites
may
result
in
mortality
to
freshwater
fish.
Three
fish
kills
associated
with
tobacco
and
wheat
were
reported
to
the
Agency
in
which
disulfoton
and
or
two
metabolites
–
the
sulfoxide
and
sulfone
were
present.
These
metabolites
are
persistent
and
1/
3
to
1/
5
less
toxic
than
disulfoton;
they
may
have
contributed
to
the
impact.
However,
it
should
be
noted
that
other
toxic
chemicals
were
also
discovered
in
the
water
in
two
of
the
incidents
and
in
the
other
instance
runoff
contributed
decaying
vegetation
and
sediment
that
may
have
resulted
in
very
low
oxygen
levels.

(ii)
Freshwater
Invertebrates
a
Acute
Risk
The
fresh
water
invertebrate
acute
risk
RQs
range
from
<0.01
(soil
injection
of
the
EC
to
any
crop
or
one
unincorporated
application
of
the
15
G
by
ground
equipment
to
soil
at
1.0
lb
ai/
A
to
wheat)
to
4.8
(1
aerial
application,
followed
by
incorporation,
of
4.0
lb
ai/
A
to
soil
for
tobacco).
Acute
risk
is
usually
exceeded
by:
1)
one
incorporated
or
unincorporated
application
of
the
EC
at
rates
equal
to
or
greater
than
1.0
lb
ai/
A;
2)
one
unincorporated
application
of
the
15
G
at
rates
equal
to
or
greater
than
1.0
lb
ai/
A;
3)
2
or
more
aerial
unincorporated
applications
of
the
EC
at
rates
equal
to
or
greater
than
0.2
lbs
ai/
A.
4)
2
or
more
unincorporated
ground
applications
of
the
EC
at
rates
equal
to
or
greater
than
0.5
lbs
ai/
A.
The
restricted
use
LOC
is
exceeded
by
nearly
all
techniques
for
all
modeled
sites.
The
exceptions
are
soil
injection
applications
of
the
EC;
one
unincorporated
application
of
the
15
G
by
ground
equipment
to
soil
at
1.0
lb
ai/
A
to
wheat
and
one
soil
incorporated,
ground
application
of
the
15
G
at
2.0
lbs
ai/
A
for
chili
peppers.
All
techniques
for
all
modeled
sites
exceed
the
endangered
species
LOC
except
for
soil
injection
of
the
EC
and
one
unincorporated
application
of
the
15
G
by
ground
equipment
to
soil
at
1.0
lb
ai/
A
to
wheat.

b
Chronic
Risk
Chronic
risk
is
anticipated
from
all
regimes
for
all
modeled
sites
except
for
soil
injection
and
one
unincorporated
application
of
the
15
G
by
ground
equipment
to
soil
at
1.0
lb
ai/
A
to
17
wheat.
RQs
for
all
of
the
modeled
crop
scenarios
greatly
exceeded
the
LOC
of
one.
The
21­
day
average
EECs
for
the
modeled
sites
that
exceeded
chronic
risk
concerns
ranged
from
0.2
ppb
(chili
peppers–
single
application
of
soil
incorporated
15
G
at
2
lbs
ai/
A)
to
12
ppb
(tobacco–
a
single
aerial
application,
followed
by
soil
incorporation
of
the
EC
at
4
lbs
ai/
A).
Invertebrate
life­
cycle
testing
on
daphnia
with
disulfoton
showed
impacts
to
reproductive
parameters
(number
of
young
produced
by
adults)
as
well
as
impacts
to
survival
and
growth
occurring
between
0.037
and
0.07
ppb.
With
the
exception
of
soil
injection
of
the
EC
formulation
(where
residues
in
water
were
considered
to
be
zero)
the
RQs
ranged
from
5
to
324.
Because
invertebrates
have
a
short
life
cycle,
their
reproduction
is
more
likely
to
be
at
least
temporarily
impacted
by
a
brief
exposure
of
adults
to
disulfoton
concentrations
near
the
NOAEC.

A
microcosm
study
toxic
suggests
that
disulfoton's
impacts
to
the
invertebrate
community
may
be
short
term
and
only
slightly
extended
due
to
the
toxicity
and
persistence
of
the
degradates
of
disulfoton.
Similarly
to
their
toxicity
to
freshwater
fish
the
two
primary
degradates
–
D.
sulfone
and
D.
sulfoxide
–
are
respectively
approximately
1/
3
to
1/
5
as
acutely
toxic
as
parent
disulfoton..
The
chronic
toxicity
to
daphnia
magna
of
these
two
degradates
is
approximately
1/
3
(for
D.
sulfone)
and
1/
45
(for
D.
sulfoxide).
The
invertebrates
were
dosed
four
times
during
the
first
28
days
of
the
77
day
study.
An
analysis
of
the
data
suggests
short
term
negative
impact
from
exposure
as
low
as
3
ppb,
but
recovery
occurred
by
the
end
of
the
study
for
most
invertebrate
populations
exposed
to
30
ppb.
It
should
be
noted
that
at
this
time
the
Agency
has
not
validated
the
significance
of
microcosm
studies.

(iii)
Estuarine
and
Marine
Fish
–
Acute
and
Chronic
Risk
There
is
uncertainty
in
using
the
PRZM/
EXAMS
EECs
derived
for
ponds
to
predict
exposure
to
marine/
estuarine
organisms.
The
scenarios
modeled
are
based
on
hydrologic
data
for
ponds.
Estuarine
fish
residing
in
the
upper
reaches
of
tributaries
of
bays
would
be
exposed
to
residues
coming
from
adjacent
crop
lands.
Exposure
to
pesticide
residues
in
estuarine
habitats
may
be
higher
or
lower
than
that
predicted
for
pond,
depending
upon
the
volume
of
water
and
residence
time
in
the
estuary.
An
additional
uncertainty
is
the
fact
that
the
only
species
tested

Sheepshead
minnow­­
probably
does
not
represent
the
true
range
of
sensitivity
of
marine
or
estuarine
fish;
therefore
both
the
acute
and
chronic
risk
may
be
underestimated.
Nevertheless,
acute
risk
to
estuarine
and
marine
fish
appears
to
be
low,
because
the
RQs
for
all
modeled
crops
are
less
than
0.05
–the
LOC
for
endangered
species.

Concerning
chronic
risk,
in
addition
to
the
previously
stated
uncertainties,
other
uncertainties
are
the
duration
adult
fish
must
be
exposed
to
disulfoton
for
their
reproductive
systems
to
be
effected
and
when
in
their
reproductive
cycle
is
the
impact
occurring.
For
example,
even
if
adults
are
effected
after
an
exposure
of
only
a
week,
disulfoton
residues
may
dissipate
from
an
area
within
several
days
resulting
in
little
or
no
chronic
risk.
However,
based
on
modeling
and
the
results
(endpoints
of
concern
included
fecundity,
hatching
success,
and
growth)
of
the
fish
full
life­
cycle
test
only
some
of
the
uses
on
3
crops
–
tobacco,
cotton
and
barley
–
slightly
exceed
the
chronic
risk
levels
of
concern.
The
RQs
showing
exceedences
range
18
from
2
for
barley
(
2
lb
ai/
A,
2
applications
at
21
day
intervals)
to
5
for
tobacco
(a
single
application
of
the
liquid
formulation
at
4
lb
ai/
A).
All
other
modeled
uses
had
RQs
less
than
the
level
of
concern
of
1.

(iv)
Estuarine
and
Marine
Invertebrates
–
Acute
and
Chronic
Risk
Similar
to
the
risk
assessment
for
estuarine
fish
the
same
uncertainties
associated
with
exposure
apply
to
estuarine
invertebrates.
Most
of
the
modeled
scenarios
do
not
exceed
the
acute
or
restricted
use
criteria
for
marine
and
estuarine
invertebrates.
The
RQs
range
from
<0.01
(a
single
soil
injected
application
of
1­
2.5
lbs
ai/
A
for
a
variety
of
vegetables)
to
1.26
(
one
aerial
application
of
the
liquid
formulation
at
4
lbs
ai/
A
to
tobacco).
Although
nearly
all
uses
exceeded
endangered
species
risk
concerns,
currently
there
are
no
marine
or
estuarine
invertebrates
listed
as
endangered.
Few
of
the
modeled
crop
scenarios
show
the
potential
for
chronic
risk
to
marine
and
estuarine
invertebrates;
those
that
do
(ie
some
uses
in
tobacco,
cotton
and
barley)
have
RQs
between
1
and
5.
Mysid
shrimp
are
less
sensitive
than
daphnia,
the
surrogate
for
freshwater
invertebrates;
therefore,
on
the
basis
of
this
limited
data,
the
chronic
impact
to
estuarine
invertebrates
appears
to
be
lower
than
freshwater
invertebrates.

The
following
3
tables
–
13
thru
15
–
contain
the
Estimated
Environmental
Concentrations
(EECs)
and
Risk
Quotients
(RQs)
for
the
risk
assessment
for
freshwater
and
estuarine
organisms.
19
Table
13.
Tier
II
Upper
Tenth
Percentile
EECs
for
Disulfoton
Parent
Used
on
barley,
cotton,
potatoes,

tobacco,
and
wheat
for
current
and
proposed
applications
estimated
using
PRZM3/
EXAMS
Crop
Disulfoton
Application
Concentration
(
:
g/
L)

(1­
in­
10
annual
yearly
maximum
value)
Mean
of
Annual
Means
(
:
g/
L)

Rate/
Number
of
Apps/
Interval/
Incorp.

Depth
/
method
1
lb.
ai/
A/
#/
days/
inches
Peak
96­
Hour
Avg.
21­
Day
Avg.
60­
Day
Avg.
90­
Day
Avg.
Annual
Avg.

Tobacco
4.0/
1/
0/
2.5/
a,
s
18.97
17.26
11.86
7.12
4.91
1.24
0.83
Tobacco
4.0/
1/
0/
2.5/
g,
s
12.02
10.93
8.08
4.39
3.04
0.76
0.35
Tobacco
4.0/
1/
0/
2.5/
g,
s
(granular)
2.
09
1.
90
1.
41
0.
75
0.
52
0.
13
0.
05
Barley
1.0
/2/
21/
0/
a,
f
8.
28
7.
44
5.
52
3.
58
2.
91
0.
75
0.
49
Barley
1.0
/2/
21/
0/
g,
f
6.
61
5.
94
4.
47
2.
65
2.
04
0.
52
0.
25
Barley
1.0/
2/
21/
0/
g,
s
(granular)
6.
41
5.
75
4.
35
2.
56
1.
90
0.
47
0.
19
Cotton
1.
0
/1/
0/
2.5/
g,
s
4.28
3.89
2.83
1.46
1.00
0.25
0.10
Cotton
SLN
(TX)
0.2/
2/
21/
0
/a,
f
2.71
2.36
1.55
0.92
0.66
0.18
0.13
Cotton
1.
0/
1/
0/
2.50/
g,
s
(granular)
0.
79
0.
72
0.
52
0.
27
0.
19
0.
05
0.
02
Cotton,
wheat
1/
1/
0/
2.5/
g,
s
(injection)
0.00
0.00
0.00
0.00
0.00
0.00
0.00
Potatoes
0.5
/3/
14/
0/
a,
f
2.
91
2.
59
2.
07
1.
33
0.
94
0.
23
0.
20
Potatoes
3.0/
1/
0/
0/
g,
s
2.
53
2.
26
1.
74
0.
92
0.
63
0.
17
0.
11
Potatoes
3.0/
1/
0/
2.5/
g,
s
1.
81
1.
63
1.
27
0.
64
0.
44
0.
11
0.
09
Potatoes
0.5
/3/
14/
0/
g,
f
1.
32
1.
18
0.
87
0.
50
0.
36
0.
09
0.
06
Potatoes
3.0/
1/
0/
2.5/
g,
s
(granular)
0.
53
0.
47
0.
35
0.
18
0.
12
0.
03
0.
11
Sorghum
0.5/
2/
14/
0a,
f
2.98
2.59
1.74
1.04
0.71
0.20
0.13
Crop
Disulfoton
Application
Concentration
(
:
g/
L)

(1­
in­
10
annual
yearly
maximum
value)
Mean
of
Annual
Means
(
:
g/
L)

Rate/
Number
of
Apps/
Interval/
Incorp.

Depth
/
method
1
lb.
ai/
A/
#/
days/
inches
Peak
96­
Hour
Avg.
21­
Day
Avg.
60­
Day
Avg.
90­
Day
Avg.
Annual
Avg.

20
Sorghum
0.5/
2/
3/
0a,
f
2.90
2.52
1.76
0.94
0.64
0.18
0.13
Sorghum
0.5/
2/
14/
0g,
f
2.
00
1.
74
1.
03
0.
55
0.
38
0.
11
0.
04
Sorghum
1/
1/
0/
4
g,
s
(granular)
0.
86
0.
78
0.
51
0.
23
0.
16
0.
05
0.
02
Winter
wheat
0.75/
1//
0/
0
a,
f
2.
19
1.
98
1.
54
0.
77
0.
53
0.
14
0.
11
Winter
wheat
0.75/
1//
0/
0
g,
f
0.
95
0.
85
0.
60
0.
30
0.
21
0.
05
0.
03
Winter
wheat
1/
1/
0/
0
g,
s
(granular)
0.
00
0.
00
0.
00
0.
00
0.
00
0.
00
0.
00
Spring
Wheat
0.75/
1//
0/
0
a,
f
2.
10
1.
96
1.
54
0.
86
0.
59
0.
16
0.
13
Values
are
Tier
II
Estimated
Environmental
Concentrations
(EECs)
for
Disulfoton
Parent
using
PRZM/
EXAMS
based
on
Current
and
Proposed
Rates
for
Disulfoton
All
EECs
are
the
1­
in­
10
annual
yearly
maximum
values.

1
Method
of
application:
g
=
ground,
a
=
aerial
f
=
foliar
and
s
=
soil;
unless
specified
the
emulsifiable
concentrate
(EC)
was
modeled.
21
Table
14.
Acute
Risks
to
Freshwater
and
Estuarine
Organisms
Potentially
Exposed
to
Disulfoton
in
Surface
Water
Use
Scenario
Risk
Quotients
(RQs
=
EEC/
Tox
value)
for
Aquatic
Organisms
Crop
and
Formulation
(liquid
unless
specified)
Application
Rate
(lbs
ai/
A)/

Method/
Site
(foliar
or
soil)
Number
of
Applications
per
Season
Time
Interval
between
Applications
(days)
Peak
(ppb
ai)
Freshwater
Estuarine
Fish
(Bluegill)
LC50
39
ppb
Invertebrates
(glass
shrimp)
LC50
3.9
ppb
Fish
(Sheepshead
Minnow)
LC50
520
ppb
Invertebrates
(Brown
Shrimp)
LC50
15
ppb
Tobacco
4,
aerial
(soil)

incorporated
1
N/
A
19
0.48
4.8
0.
04
1.
26
4,
ground
(soil)

incorporated
1
N/
A
12
0.30
3
0.
02
0.
80
Tobacco
(Granular)
4,
ground
(soil)

incorporated
1
N/
A
2
0.
05
0.
5
<0.01
0.
13
Barley
Asparagus
1
1,
aerial
(foliar)
2
21
8.
3
0.21
2.1
0.
02
0.
55
1,
ground
(foliar)
2
21
6.
6
0.17
1.7
0.
01
0.
44
Barley
(Granular)
1,
ground
(soil)

unincorporated
2
21
6.
4
0.16
1.6
0.
01
0.
43
Cotton
1,
ground
(soil)

incorporated
1
N/
A
4.3
0.
11
1.
1
<0.01
0.
28
Cotton
(SLN)

TX
0.2,
aerial
(foliar)
2
21
2.
7
0.07
0.7
<0.01
0.18
Cotton
(granular)
1,
ground
(soil)

incorporation
1
N/
A
0.8
2
0.02
0.2
<0.01
0.05
Sorghum
0.5,
aerial
(foliar)
2
3
approx
3
0.
08
0.
77
<0.01
0.20
14
Sorghum
0.5,
ground
(foliar)
2
14
2
0.05
0.5
<0.01
0.13
Use
Scenario
Risk
Quotients
(RQs
=
EEC/
Tox
value)
for
Aquatic
Organisms
Crop
and
Formulation
(liquid
unless
specified)
Application
Rate
(lbs
ai/
A)/

Method/
Site
(foliar
or
soil)
Number
of
Applications
per
Season
Time
Interval
between
Applications
(days)
Peak
(ppb
ai)
Freshwater
Estuarine
Fish
(Bluegill)
LC50
39
ppb
Invertebrates
(glass
shrimp)
LC50
3.9
ppb
Fish
(Sheepshead
Minnow)
LC50
520
ppb
Invertebrates
(Brown
Shrimp)
LC50
15
ppb
22
Sorghum
1,
ground
(soil)

incorporated
1
N/
A
between
0.9
and
2
0.04
3
0.4
3
<0.01
3
0.10
3
Sorghum
(granular)
1,
ground
(soil)

incorporated
1
N/
A
0.9
0.
02
0.
2
<0.01
0.
06
Cotton,
peanuts,
sorghum
(granular)
1,
ground
(soil)
in
furrow
1
N/
A<
0.
8
3
<0.02
<0.2
<0.01
<0.05
Cotton
1,
ground
(soil)

injection
1
1
approx
zero
<0.01
<0.01
<0.01
<0.01
Potatoes
0.5,
aerial
(foliar)
3
14
2.
9
0.07
0.7
<0.01
0.19
3,
ground
(soil)

unincorporated
1
N/
A
2.5
0.
06
0.
6
<0.01
0.
17
3,
ground
(soil)

in
furrow
1
N/
A
1.8
0.
05
0.
5
<0.01
0.
12
0.5,
ground
(foliar)
3
14
1.
3
0.33
0.3
<0.01
0.09
Potatoes
(N.
West
only)
4
3,
ground
(foliar)
chemigation
1
N/
A
between
1.8
and
2.5
0.05
5
0.5
5
<0.01
5
N/
A
0.14
5
N/
A
Potatoes
(granular)
3,
ground
(soil)

incorporated
1
N/
A
0.5
0.
01
0.
1
<0.01
0.
03
Peas,
lentiles
6
2.5,
ground
(soil)
in
furrow
1
N/
A
2.5
0.
06
0.
6
<0.01
0.
17
Wheat
(Fall)
0.75,
aerial
(foliar)
1
N/
A
2.1
0.
05
0.
5
<0.01
0.
14
Use
Scenario
Risk
Quotients
(RQs
=
EEC/
Tox
value)
for
Aquatic
Organisms
Crop
and
Formulation
(liquid
unless
specified)
Application
Rate
(lbs
ai/
A)/

Method/
Site
(foliar
or
soil)
Number
of
Applications
per
Season
Time
Interval
between
Applications
(days)
Peak
(ppb
ai)
Freshwater
Estuarine
Fish
(Bluegill)
LC50
39
ppb
Invertebrates
(glass
shrimp)
LC50
3.9
ppb
Fish
(Sheepshead
Minnow)
LC50
520
ppb
Invertebrates
(Brown
Shrimp)
LC50
15
ppb
23
Wheat
(Spring)
0.75,
aerial
(foliar)
1
N/
A
2.2
0.
06
0.
6
<0.01
0.
15
0.75,
ground
(foliar)
1
N/
A
0.9
0.
02
0.
2
<0.01
0.
06
Wheat
(granular)
1,
ground
(soil)

unincorporated
1
N/
A
<0.01
<0.01
<0.01
<0.01
<0.01
Chili
peppers
7
2,
ground
(soil)

incorporated.
1
N/
A
1.2
0.
03
0.
3
<0.01
0.
08
Chili
peppers
8
(granular)
2,
ground
(soil)

incorporated.
1
N/
A
0.3
<0.01
0.07
<0.01
0.
02
Peas,
lentils
Beans
(snap,

dry
&
lima),
lettuce,
broccoli,
cauliflower,
brussels
sprouts,
cabbage,
wheat,
barley
9
1
to
2.5,
ground
(soil)

injection
1
N/
A
approx
zero
<0.01
<0.01
<0.01
<0.01
1
The
RQs
for
asparagus
in
the
N
West
are
assumed
to
be
much
less
than
for
foliar
applications
to
barley
even
though
there
is
potential
for
three
applications..

There
is
little
or
no
rainfall
causing
runoff
during
the
application
period.
(Personnel
communication
with
Alan
Schriber
Wash
State
Dept
of
Ag).
However,
EECs
may
be
higher
where
rainfall
is
expected.

2
In
furrow
locates
most
of
the
applied
material
lower
in
the
soil
profile
than
incorporation
by
tillage;
therefore
exposure
from
run
off
will
be
less.

3
RQ
derived
from
the
average
of
the
range
of
EECs
(1.45)
divided
by
the
toxicity
value.

4
Other
potato
scenarios
were
for
Maine
where
run
off
and
rainfall
is
greater
than
N
West.
Although
drift
may
be
greater
than
conventional
ground
spray
(1
%)

the
proximity
to
adjacent
water
bodies
is
farther
in
the
N
West.
Finally,
the
amount
available
for
runoff
is
less
when
material
is
applied
to
foliage
rather
than
soil.

5
RQ
derived
from
the
average
of
the
range
of
EECs
(2.15)
divided
by
the
toxicity
value.

6
EEC
is
estimated
to
be
proportional
to
the
EEC
for
potato
(3
lb
ai/
A
ground
application
of
liquid
when
in
furrow)
24
7
EEC
estimated
to
be
proportional
to
the
EEC
for
potato
(3
lb
ai/
A
ground
application
of
liquid,
soil
incorporation)

8
EEC
estimated
to
be
proportional
to
the
EEC
for
potato
(3
lb
ai/
A
ground
application
granular,
soil
incorporation)

9
EEC
is
estimated
to
be
the
same
as
for
cotton
(1
lb
ai/
A
ground
application
of
liquid
when
injected
=
approx.
zero)

Based
on
the
data
described
above,
disulfoton
poses
the
greatest
acute
risk
to
freshwater
invertebrates
and
the
least
risk
to
estuarine
fish.

Table
15.
Chronic
Risks
to
Freshwater
and
Estuarine
Organisms
Potentially
Exposed
to
Disulfoton
in
Surface
Water
Use
Scenario
Risk
Quotients
(RQs
=EEC/
NOAEC)
1
for
Aquatic
Organisms
Crop
and
Formulation
(liquid
unless
specified)
Application
Rate
(lbs
ai/
A)/

Method/
Site
(foliar
or
soil)
Number
of
Applications
per
Season
Time
Interval
between
Applications
(days)
Day
Ave
(ppb
ai)
Freshwater
Estuarine
21
60
90
Fish
(Bluegill)
2
4.6
ppb
Invertebrates
(Daphnia)
0.037
ppb
Fish
(Sheepshead
Minnow)
3
0.96
­
16.2
ppb
Invertebrates
(Mysid
Shrimp)
2.35
ppb
Tobacco
4,
aerial
(soil)

incorporated
1
N/
A
12
7
5
1.
5
324
0.4
­
5
5
4,
ground
(soil)

incorporated
1
N/
A8
4
3
0.
92160.
2
­
33
Tobacco
(Granular)
4,
ground
(soil)

incorporated
1
N/
A
1.4
0.
7
0.5
0.
1
38
<0.1
­
0.5
0.
6
Barley,
asparagus
4
1,
aerial
(foliar)
2
21
5.
5
3.6
2.
9
0.8
149
0.2
­
3
2.
3
1,
ground
(foliar)
2
21
4.
5
2.6
2
0.6
122
0.2
­
2
1.
9
Barley
(Granular)
1,
ground
(soil)

unincorporated
2
21
4.
3
2.5
1.
9
0.5
116
0.1
­2
1.8
Use
Scenario
Risk
Quotients
(RQs
=EEC/
NOAEC)
1
for
Aquatic
Organisms
Crop
and
Formulation
(liquid
unless
specified)
Application
Rate
(lbs
ai/
A)/

Method/
Site
(foliar
or
soil)
Number
of
Applications
per
Season
Time
Interval
between
Applications
(days)
Day
Ave
(ppb
ai)
Freshwater
Estuarine
21
60
90
Fish
(Bluegill)
2
4.6
ppb
Invertebrates
(Daphnia)
0.037
ppb
Fish
(Sheepshead
Minnow)
3
0.96
­
16.2
ppb
Invertebrates
(Mysid
Shrimp)
2.35
ppb
25
Cotton
1,
ground
(soil)

incorporated
1
N/
A
2.8
1.
5
1
0.
3
76
<0.1
­
1
1.
2
Cotton
(SLN)

TX
0.2,
aerial
(foliar)
2
21
1.
5
0.9
0.
7
0.2
40
<0.1
­
0.7
0.
6
Cotton
(granular)
1,
ground
(soil)

incorporation
1
N/
A
0.5
5
0.3
5
0.2
5
<0.1
13
<0.1
­
0.2
0.
2
Sorghum
0.5,
aerial
(foliar)
2
3
approx
1.7
approx
1.0
approx
0.7
0.2
46
<0.1
­
0.7
0.
7
14
Sorghum
0.5,
ground
(foliar)
2
14
1.
0
0.5
0.
4
0.1
27
<0.1
­
0.4
0.
4
Sorghum
1,
ground
(soil)

incorporated
1
N/
A
between
0.5
and
1.0
between
0.2
and
0.5
between
0.1
and
0.4
<0.1
6
19
6
<0.1
­
0.2
6
0.3
6
Sorghum
(granular)
1,
ground
(soil)

incorporated
1
N/
A
0.5
0.
2
0.1
<0.1
13
<0.1
­
0.1
0.
2
Cotton,
peanuts,
sorghum
(granular)
1,
ground
(soil)
in
furrow
1
N/
A<
0.
5
6
<0.3
6
<0.2
6
<0.1
<13
<0.1
­<
0.2
<0.2
Cotton
1,
ground
(soil)

injection
1
N/
A
approx
zero
approx
zero
approx
zero
<0.01
<0.01
<0.01
<0.01
Potatoes
0.5,
aerial
(foliar)
3
14
2
1.3
0.
9
0.3
54
<0.1
­
0.9
0.
8
3,
ground
(soil)

unincorporated
1
N/
A
1.7
0.
9
0.6
0.
2
50
<0.1
­
0.6
0.
7
Use
Scenario
Risk
Quotients
(RQs
=EEC/
NOAEC)
1
for
Aquatic
Organisms
Crop
and
Formulation
(liquid
unless
specified)
Application
Rate
(lbs
ai/
A)/

Method/
Site
(foliar
or
soil)
Number
of
Applications
per
Season
Time
Interval
between
Applications
(days)
Day
Ave
(ppb
ai)
Freshwater
Estuarine
21
60
90
Fish
(Bluegill)
2
4.6
ppb
Invertebrates
(Daphnia)
0.037
ppb
Fish
(Sheepshead
Minnow)
3
0.96
­
16.2
ppb
Invertebrates
(Mysid
Shrimp)
2.35
ppb
26
3,
ground
(soil)

in
furrow
1
N/
A
1.3
0.
6
0.4
0.
1
35
<0.1
­
0.4
0.
5
0.5,
ground
(foliar)
3
14
0.
9
0.5
0.
4
0.1
24
<0.1
­
0.4
0.
4
Potatoes
(N.
West
only)
7
3,
ground
(foliar)
chemigation
1
N/
A
between
1.3
and
1.7
between
0.6
and
0.9
between
0.4
and
0.6
0.1
8
40
8
<0.1
­
0.5
8
N/
A
0.6
8
N/
A
Potatoes
(granular)
3,
ground
(soil)

incorporated
1
N/
A
0.3
0.
2
0.1
<0.1
8
<0.1
­
0.1
0.
1
Peas,
lentiles
9
2.5,
ground
(soil)
in
furrow
1
N/
A
1.1
0.
5
0.3
0.
1
30
<0.1
­
0.3
0.
5
Wheat
(Fall)
0.75,
aerial
(foliar)
1
N/
A
1.5
0.
9
0.6
0.
2
40
<0.1
­
0.6
0.
6
Wheat
(Spring)
0.75,
aerial
(foliar)
1
N/
A
1.5
0.
8
0.5
0.
2
40
<0.1
­
0.5
0.
6
0.75,
ground
(foliar)
1
N/
A
0.6
0.
3
0.2
<0.1
16
<0.1
­
0.2
0.
3
Wheat
(granular)
1,
ground
(soil)

unincorporated
1
N/
A
0.002
0.001
0.001
<0.01
<0.1
<0.01
<0.01
Chili
peppers
10
2,
ground
(soil),
incorp.
1
N/
A
0.8
0.
4
0.3
<.
1
21
<0.1
­
0.3
0.
3
Chili
peppers
11
granular
2,
ground
(soil),
incorp.
1
N/
A
0.2
0.
1
0.07
<0.1
5
<0.1
<0.1
Use
Scenario
Risk
Quotients
(RQs
=EEC/
NOAEC)
1
for
Aquatic
Organisms
Crop
and
Formulation
(liquid
unless
specified)
Application
Rate
(lbs
ai/
A)/

Method/
Site
(foliar
or
soil)
Number
of
Applications
per
Season
Time
Interval
between
Applications
(days)
Day
Ave
(ppb
ai)
Freshwater
Estuarine
21
60
90
Fish
(Bluegill)
2
4.6
ppb
Invertebrates
(Daphnia)
0.037
ppb
Fish
(Sheepshead
Minnow)
3
0.96
­
16.2
ppb
Invertebrates
(Mysid
Shrimp)
2.35
ppb
27
Peas,
lentils
beans
(snap,

dry
&
lima),
lettuce,
broccoli,
cauliflower,
brussels
sprouts,
cabbage,
wheat,
12
1
to
2.5,
ground
(soil),

injection
1
N/
A
approx
zero
approx
zero
approx
zero
<0.01
<0.01
<0.01
<0.01
1Risk
quotients
for
fresh
water
/
estuarine
invertebrates
and
freshwater
fish
are
based
on
21
and
60
day
EECs,
respectively.

2
Bluegill
NOAEC
(4.6
ppb)
is
derived
from
the
less
sensitive
rainbow
trout
chronic:
acute
ratio
of
0.119.

3
Risk
quotients
for
estuarine
fish
are
based
on
60
and
90
day
EECs.
Lower
value
derived
is
from
60
EEC
and
fish
early
life
stage
(fertilized
egg
through
swim­
up
stage
of
larvae).
Higher
value
is
from
90
day
EEC
and
full
life
cycle
(fertilized
egg
through
survival
of
juveniles
of
next
generation).

4
The
RQs
for
asparagus
in
the
N
West
are
assumed
to
be
less
than
for
foliar
applications
to
barley
even
though
there
is
potential
for
three
applications.
There
is
little
or
no
rainfall
causing
runoff
during
the
application
period.
(Personnel
communication
with
Alan
Schriber
Wash
State
Dept
of
Ag).
However,
EECs
may
be
higher
where
rainfall
is
expected.

5
In
furrow
locates
most
of
the
applied
material
lower
in
the
soil
profile
than
incorporation
by
tillage;
therefore
exposure
from
run
off
will
be
less.

6
RQ
derived
from
the
average
of
the
range
of
EECs
divided
by
the
toxicity
value.
The
averages
are
as
follows:
21
day
ave.=
0.7,
60
day
ave.=
0.3,
90
day
ave=
0.2.

7
Other
potato
scenarios
were
for
Maine
where
run
off
and
rainfall
is
greater
than
N
West.
Although
drift
may
be
greater
than
conventional
ground
spray
(1
%)

the
proximity
to
adjacent
water
bodies
is
farther
in
the
N
West.
Finally,
the
amount
available
for
runoff
is
less
when
material
is
applied
to
foliage
rather
than
soil.

8
RQ
derived
from
the
average
of
the
range
of
EECs
divided
by
the
toxicity
value.
The
averages
are
as
follows:
21
day
ave.=
1.5,
60
day
ave.=
0.7,
90
day
ave=
0.5.

9
EEC
is
estimated
to
be
proportional
to
the
EEC
for
potato
(3
lb
ai/
A
ground
application
of
liquid
when
in
furrow)

10
EEC
estimated
to
be
proportional
to
the
EEC
for
potato
(3
lb
ai/
A
ground
application
of
liquid,
soil
incorporation)

11
EEC
estimated
to
be
proportional
to
the
EEC
for
potato
(3
lb
ai/
A
ground
application
granular,
soil
incorporation)

12
EEC
is
estimated
to
be
the
same
as
for
cotton
(1
lb
ai/
A
ground
application
of
liquid
when
injected
=
approx.
zero)

Based
on
the
data
described
above,
freshwater
invertebrates
are
at
greater
chronic
risk
than
fish
or
estuarine
invertebrates.
28
Risks
to
Nontarget
Organisms
from
the
use
of
Disulfoton
15
on
Christmas
Trees
in
North
Carolina
The
use
of
Disulfoton
15
G
in
Christmas
tree
farms
at
this
time
can
not
be
modeled
for
potential
surface
water
contamination.
EFED
assumes
the
estimated
concentration
for
the
North
Carolina
24
(c)
use
pattern
­­
4.5
lbs
ai/
A
unincorporated
­­
may
be
similar
to
the
values
for
the
single
4.0
lb
ai/
A
incorporated
application
of
granular
disulfoton
to
tobacco.
Based
on
this
assumption
there
is
potential
for
acute
risk
and
chronic
to
aquatic
invertebrates
and
chronic
risk
to
freshwater
fish.
This
assumption
would
be
more
likely
when
the
receiving
body
of
water
is
a
pond,
rather
than
a
stream.
The
Christmas
tree
use
pattern
has
a
higher
rate
than
tobacco;
the
granules
are
unincorporated;
and
current
cultural
practices
recommend
maintaining
vegetation
under
the
trees
and
between
the
rows.
Therefore
while
the
first
two
conditions
may
increase
the
estimated
concentrations
above
those
for
tobacco,
the
third
condition
may
reduce
the
concentrations
as
the
absence
of
soil
erosion
reduces
the
amount
of
disulfoton
moving
off
site.
Since
this
preliminary
screen
of
the
24(
c)
exceeds
levels
of
concern,
the
Sec
3
use
at
59.7
lbs
ai/
A
would
exceed
(perhaps
by
20
fold)
the
same
levels
of
concern
for
aquatic
life
as
well
as
the
acute
risk
for
fish.

The
North
Carolina
Christmas
tree
industry
has
provided
information
that
has
contributed
to
a
refinement
of
EFED's
risk
assessment
for
aquatic
organisms
from
Christmas
tree
farming.
First,
the
nearly
exclusive
use
for
Disulfoton
15
G
on
Christmas
trees
throughout
the
United
States
is
on
Fraser
fir
grown
in
6
counties
in
Western
North
Carolina,
thereby
localizing
the
exposure
and
precluding
any
estuarine
exposure.
Second,
the
primary
aquatic
sites
adjacent
to
tree
farms
are
streams,
not
ponds.
Residues
in
these
streams
will
be
lower
and
of
shorter
duration
than
would
be
expected
for
a
pond.
Third,
two
rapid
assessment
macro
invertebrate
surveys
of
streams
in
the
Western
region
of
North
Carolina
have
been
submitted.
These
studies
show
that
when
conservation
measures
associated
with
Christmas
tree
farming
in
the
Western
counties
of
North
Carolina
are
implemented,
there
may
be
only
slight,
short
term
impact
to
aquatic
macro
invertebrates
from
disulfoton
use.
The
Agency
concurs
with
the
investigators
that
when
implementing
(but
not
limited
to)
conservation
measures
such
as
establishing
ground
cover
throughout
the
farm,
constructing
and
maintaining
the
fewest
number
of
roads
and
bridges,
creating
a
riparian
zone
to
include
vegetation
and
trees
and
employing
Integrated
Pest
Management
practices,
there
appears
to
be
"
...
little
negative
effect
on
the
fauna
of
adjacent
streams...."
The
slight
negative
effect
that
was
observed
seemed
to
impact
stoneflies
(Plecoptera)
more
than
the
two
other
orders–
caddisflies
(Trichoptera)
and
mayflies
(Ephemeroptera)
­
that
were
the
focus
of
the
survey.
In
conclusion,
aquatic
macro
invertebrates
appear
to
have
the
capacity
to
recover
from
impacts
that
could
be
caused
by
disulfoton
use
on
Christmas
trees
in
Western
North
Carolina.

(e)
Nontarget
Plants
EPA
was
unable
to
conduct
a
risk
assessment
for
nontarget
plants
due
to
a
lack
of
test
data.
Nontarget
plant
testing
was
not
required
for
disulfoton
because
it
is
not
a
herbicide.
r,
the
Di­
Syston
8
EC
label
contains
phytotoxicity
statements
suggesting
a
potential
risk
to
nontarget
plants.
Therefore
Tier
1
seedling
emergence
(850.4100)
and
Tier
I
vegetative
vigor
(850.4150)
are
requested
to
support
the
liquid
formulations
of
disulfoton.

(f)
Endangered
Species
29
For
disulfoton,
EPA
has
risk
concerns
for
the
following
scenarios:
avian
acute,
avian
chronic,
mammalian
acute,
mammalian
chronic,
freshwater
fish
acute,
freshwater
invertebrate
acute,
freshwater
invertebrate
chronic,
marine/
estuarine
fish
acute,
marine/
estuarine
fish
chronic,
marine/
estuarine
invertebrate
acute,
and
marine/
estuarine
invertebrate
chronic.
Endangered
terrestrial,
semi­
aquatic
and
aquatic
plants
also
may
be
affected,
based
on
label
statements
indicating
phytotoxicity.

The
Agency
has
developed
the
Endangered
Species
Protection
Program
to
identify
pesticides
whose
use
may
cause
adverse
impacts
on
endangered
and
threatened
species,
and
to
implement
mitigation
measures
that
address
these
impacts.
The
Endangered
Species
Act
requires
federal
agencies
to
ensure
that
their
actions
are
not
likely
to
jeopardize
listed
species
or
adversely
modify
designated
critical
habitat.
To
analyze
the
potential
of
registered
pesticide
uses
to
affect
any
particular
species,
EPA
puts
basic
toxicity
and
exposure
data
developed
for
REDs
into
context
for
individual
listed
species
and
their
locations
by
evaluating
important
ecological
parameters,
pesticide
use
information,
the
geographic
relationship
between
specific
pesticides
uses
and
species
locations,
and
biological
requirements
and
behavioral
aspects
of
the
particular
species.
This
analysis
will
include
consideration
of
the
regulatory
changes
recommended
in
this
RED.
A
determination
that
there
is
a
likelihood
of
potential
impact
to
a
listed
species
may
result
in
limitations
on
use
of
the
pesticide,
other
measures
to
mitigate
any
potential
impact,
or
consultations
with
the
Fish
and
Wildlife
Service
and/
or
the
National
Marine
Fisheries
Service
as
necessary.

At
present,
the
program
is
being
implemented
on
an
interim
basis
as
described
in
a
Federal
Register
notice
(54
FR
27984­
28008,
July
3,
1989).
A
final
program,
which
may
be
altered
from
the
interim
program,
will
be
proposed
in
a
Federal
Register
notice
scheduled
for
publication
in
autumn
of
2001.

(g)
Ecological
Incident
Reports
Several
reports
of
wildlife
poisonings
are
associated
with
disulfoton.
These
poisoning
incidents
are
summarized
in
Table
16
below.
Some
of
these
incident
reports
support
EPA's
concerns
for
acute
risk.
30
Table
16.
Chronological
List
of
Ecological
Incidents
Start
Date
Misuse?
(yes/
no/
un
known)
Incident
Description
6/
12/
95
unknown
Johnston
County,
NC:
Fish
kill
occurred
in
commercial
fish
pond.
Crop
fields
nearby
treated
with
pesticides.
Water,
soil
and
vegetation
samples
analyzed
for
a
variety
of
pesticides.
Disulfoton,
as
well
as
several
other
pesticides,
was
found
at
0.2­
2.5
ppm
in
vegetation
samples.
Possible
certainty
index
for
disulfoton.
(Incident
Report
No.
I003826­
002).

1/
24/
94
unknown
Puerto
Rico:
6
grackles
fell
dead
from
tree
in
yard
of
private
residence.
Dead
heron
and
owl
also
found
in
vicinity.
Use
site
and
method
not
reported.
Birds
had
depressed
acetyl
cholinesterase.
Analysis
of
GI
contents
of
a
grackles
showed
disulfoton
at
2.37
ppm
wet
weight.
Highly
probable
certainty
index
for
disulfoton.
(Incident
Report
No.
I003966­
004).

6/
11/
94
unknown
Arapahoe
CO:
Fish
kill
following
application
of
Di­
Syston
EC.
to
wheat
just
before
heavy
rain.
Water
samples
contained
disulfoton
sulfoxide
at
29.5­
48.7
ppb
and
disulfoton
sulfone
at
0.0199­
0.214
ppb.
(Incident
Report
No.
I001167­
001).

6/
18/
93
No
Young
County,
TX:
18
Swainson's
hawks
dead,
1severely
disabled
in
a
cotton
field.
Cotton
seed
had
been
treated
with
disulfoton
prior
to
planting,
~10
days
before
the
birds
were
discovered.
No
additional
applications
of
OP
or
carbamate
pesticides
made
in
vicinity
of
field.
Autopsies
showed
no
trauma
or
disease.
Lab
analysis
showed
insect
material
in
GI
tracts;
this
material
contained
disulfoton
(~
7
ppm);
no
other
OP
or
carbamate
insecticides
were
present.
Hawks
fed
on
insects,
which
had
been
feeding
on
the
young
cotton
plants,
which
contained
disulfoton
residues.
(L.
Lyon,
Div.
of
Environmental
Contaminants,
U.
S.
Fish
and
Wildlife
Service,
Arlington,
VA.)

6/
22/
91
unknown
Onslow
County,
NC:
Fish
kill
in
pond
at
private
residence.
Pond
received
runoff
from
neighboring
tobacco
field;
pondwater
analysis
showed
disulfoton
and
several
other
pesticides,
including
endosulfan.
Disulfoton
sulfoxide
found
in
water
at
0.32
ppb.
Endosulfan
had
highest
concentration
(1.2
µg/
L),
and
is
toxic
to
fish,
but
disulfoton
cannot
be
ruled
out
as
a
possible
cause
of
death.
No
tissue
analysis.
Possible
certainty
index
for
disulfoton.
(Incident
Report
No.
B0000216­
025).

4/
26/
91
unknown
Sussex
County,
DE:
9
American
robins
dead
following
application
of
granular
disulfoton
at
tree
nursery.
Corn
and
soybeans
also
in
vicinity.
No
laboratory
analysis.
Probable
certainty
index
for
disulfoton.
(Incident
Report
No.
I000116­
003).
