Document ID: EPA-HQ-OPP-2004-0380-0007
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2005-02-07T05:00Z

UNITED
STATES
ENVIRONMENTAL
PROTECTION
AGENCY
WASHINGTON,
D.
C.
20460
OFFICE
OF
PREVENTION,
PESTICIDES
AND
TOXIC
SUBSTANCES
Date:
June
08,
2004
MEMORANDUM
SUBJECT:
OCCUPATIONAL
AND
RESIDENTIAL
EXPOSURE
ASSESSMENT
AND
RECOMMENDATIONS
FOR
THE
REREGISTRATION
ELIGIBILITY
DECISION
DOCUMENT
FOR
DIMETHIPIN
FROM:
Seyed
Tadayon,
Chemist
Reregistration
Branch
III
Health
Effect
Division
(
7509C)

THRU:
Steve
Weiss,
Industrial
Hygienist
Reregistration
Branch
III
Health
Effects
Division
(
7509C)

TO:
Susan
Stanton,
Risk
Assessor
Reregistration
Branch
III
Health
Effects
Division
(
7509C)

Please
find
the
review
of
dimethipin.
DP
Barcode:
D332596
PC
Codes:
118901
EPA
Reg
Nos:
400­
155,
400­
398,
400­
432,
400­
505,
WA98000800
EPA
MRID
No:
NA
LUIS
Report:
05/
20/
2002
PHED:
Yes,
Version
1.1
2
CONTENTS
EXECUTIVE
SUMMARY
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3
1.0
BACKGROUND
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5
1.1
Summary
of
Toxicity
Concerns
Relating
to
Agricultural
Exposures
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1.2
Summary
of
Use
Pattern
and
Formulations
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6
1.3
Method
and
Types
of
Equipment
Used
for
Mixing/
Loading/
Applying
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1.4
Incident
Reports
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7
2.0
OCCUPATIONAL
EXPOSURES
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8
2.1
Handler
Exposures
&
Assumptions
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8
2.1.1
Summary
of
Uncertainties
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8
2.1.2
Calculations
of
Exposure
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11
2.2
Risk
From
Handler
Exposures
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11
2.2.1
Risk
From
Handler
Exposures
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11
2.2.2
Summary
of
Handler
Risk
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12
3.0
POSTAPPLICATION
EXPOSURES
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14
APPENDIX
A
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15
3
EXECUTIVE
SUMMARY
This
document
addresses
the
exposures
and
risks
associated
with
the
use
of
the
dimethipin,
that
occur
through
non­
dietary
exposure.
Non­
dietary
exposures
can
occur
as
a
result
of
handling
dimethipin
or
by
entering
areas
that
have
been
previously
treated
with
dimethipin.
Exposures
can
occur
as
a
part
of
one's
job
or
through
uses
of
dimethipin.
There
are
no
residential
uses
for
dimethipin.

Dimethipin,
[
2,
3
dihydro­
5,6­
dimethyl­
1,4­
dithi­
ine
1,1,4,4­
tetraoxide]
is
a
defoliant
herbicide.
Defoliants,
desiccants,
and
growth
regulators
are
chemicals
used
in
agricultural
production
to
accelerate
the
preparation
of
crops
for
mechanical
harvest.
Dimethipin
primarily
is
designed
to
inflict
sufficient
injury
to
the
leaf
to
upset
the
hormone
balance
at
the
abscission
zone
and
allow
enzymes
to
begin
the
abscission
(
i.
e.
fall
off)
process.

The
agricultural
use
sites
referenced
on
dimethipin
labels
are
apple
and
cotton.
A
wide
variety
of
application
techniques
have
been
identified
that
could
potentially
be
used
to
apply
dimethipin.
These
methods
include
high
pressure
handwand,
groundboom
sprayers
and
fixedwing
aircraft.

Dimethipin
is
formulated
as
a
manufacturing
product
(
98.0%
active
ingredient),
two
flowable
concentrate
formulations
(
48.0%
active
ingredient)
and
one
emulsifiable
concentrate
formulation
(
32.7
%
active
ingredient).

Hazard
Identification
This
risk
assessment
incorporates
the
toxicological
endpoints
of
concern
identified
by
risk
assessment
team.
No
dermal
hazard
end
point
was
identified,
therefore,
no
quantification
is
required.
Systemic
toxicity
was
not
seen
at
the
limit
dose
in
a
dermal
toxicity
rat
study.
Therefore
no
short­
intermediate
or
long­
term
occupational
or
residential
dermal
endpoint
of
concern
was
identified.

The
occupational
short­
term
inhalation
endpoint
of
concern
was
based
on
the
maternal
NOAEL
of
20
mg/
kg/
day
identified
in
an
oral
developmental
rabbit
study.
The
maternal
LOAEL
of
40
mg/
kg/
day
was
based
on
decreased
body
weight
gain
and
intermediate­
term
inhalation
Endpoint
of
concern
was
based
on
the
2­
generation
reproduction
study
in
the
rat
with
a
parental
systemic
NOAEL
of
11.8
mg/
kg/
day
(
F0
and
F1
females).
The
LOAEL
for
F0
and
F1
females
(
31.2­
120.3
mg/
kg/
day)
was
based
on
decreased
body
weights
and
body
weight
gains.
Based
on
use
pattern,
no
long­
term
inhalation
exposure
is
anticipated.

Dimethipin
has
been
classified
as
a
Group
C
(
possible
human)
carcinogen
by
the
Toxicology
Peer
Review
Committee.
The
classification
was
based
on
evidence
of
lung
adenomas
and
carcinomas
in
male
CD­
1
mouse.
The
Committee
concluded
that
the
rat
study
was
not
conducted
at
a
high
enough
dose,
and
recommended
that
a
new
study
be
conducted.
The
results
4
of
the
new
study
indicated
no
evidence
of
carcinogenicity
in
the
rat.
Calculation
of
a
Q
1*
was
not
recommended
for
dimethipin.

The
Agency's
level
of
concern
for
risks
(
i.
e.,
target
level
for
MOEs
or
Margins
of
Exposure)
is
defined
by
the
uncertainty
factors
that
are
applied
to
the
assessment.
The
Agency
applies
a
factor
of
100
to
account
for
inter­
species
extrapolation
to
humans
from
the
animal
test
species
and
to
account
for
intra­
species
sensitivity.

Occupational
Handler
Risks
Short­
and
intermediate­
term
inhalation
risks
to
occupational
handlers
at
baseline
Personal
Protective
Equipment
(
PPE)
(
i.
e.,
no
respirator)
are
below
the
Agency's
level
of
Concern
(
i.
e.,
MOE

100).
EPA
has
insufficient
data
to
assess
exposures
to
pilots
in
open
cockpits.
Inhalation
risks
to
pilots
in
enclosed
cockpits
(
i.
e.,
engineering
control
scenario)
were
also
below
the
Agency's
level
of
Concern
(
i.
e.,
MOE

100).

Short­
and
intermediate­
term
dermal
risks
were
not
assessed
for
occupational
handlers,
since
no
short­
or
intermediate­
term
dermal
endpoint
was
identified.

HED
has
determined
that
there
are
potential
exposures
to
mixers,
loaders,
applicators,
and
other
handlers
during
usual
use­
patterns
associated
with
dimethipin.
Six
major
exposure
scenarios
were
identified
for
dimethipin,
including
mixing,
loading,
and
applying
using
ground
spray
and
aerial
application.

The
results
of
the
short
and
intermediate­
term
inhalation
handler
assessments
indicate
that
all
potential
exposure
scenarios
provide
at
least
one
application
rate
with
a
total
MOE(
s)
greater
than
100
at
either
the
baseline
(
i.
e.,
no
respirator)
or
using
engineering
controls
(
i.
e.,
closed
systems).
The
MOEs
for
all
the
scenarios
range
from
880
to
1,300,000.

EPA
did
not
quantify
occupational
postapplication
risks
to
agricultural
workers
following
treatments
to
cotton
or
apple,
since
no
dermal
endpoints
of
concern
were
identified.
The
acute
toxicity
classification
for
dermal
irritation
of
dimethipin
is
tox
category
III
which
requires
a
12­
hour
REI.

On
the
list
of
the
top
200
chemicals
for
which
NPIC
received
calls
from
1984­
1991
inclusively,
dimethipin
was
not
reported
to
be
involved
in
human
incidents
relatively
few
incidents
of
illness
have
been
reported
due
to
dimethipin.
5
1.0
BACKGROUND
Purpose
In
this
document,
which
is
for
use
in
EPA's
development
of
the
dimethipin.
Reregistration
Eligibility
Decision
Document
(
RED),
EPA
presents
the
results
of
its
review
of
the
potential
human
health
effects
of
occupational
exposure
to
dimethipin.

Criteria
for
Conducting
Exposure
Assessments
An
occupational
and/
or
residential
exposure
assessment
is
required
for
an
active
ingredient
if
(
1)
certain
toxicological
criteria
are
triggered
and
(
2)
there
is
potential
exposure
to
handlers
(
mixers,
loaders,
applicators,
etc.)
during
use
or
to
persons
entering
treated
sites
after
application
is
complete.
For
dimethipin,
both
criteria
are
met.

1.1
Summary
of
Toxicity
Concerns
Relating
to
Agricultural
Exposures
The
acute
toxicity
data
base
for
dimethipin
is
considered
complete
for
acute
oral,
acute
dermal,
acute
inhalation,
dermal
and
eye
irritation,
and
dermal
sensitization.
Dimethipin
has
a
moderate
order
of
acute
toxicity
via
the
oral
(
Category
II)
and
inhalation
routes
(
Category
II).
It
has
a
low
order
of
acute
toxicity
via
the
dermal
(
Category
III)
route
of
exposure.
It
is
not
an
eye
or
skin
irritant,
or
a
dermal
sensitizer.
The
acute
toxicity
data
for
dimethipin
is
summarized
below
in
Table
1.

Table1.
Acute
Toxicity
Profile
for
Dimethipin
Guideline
Number
Study
Type
MRID
Number
Results
Toxicity
Category
870.1100(
§
81­
1)
Acute
Oral
42429601
LD50
=
458
mg/
kg
(

)
LD50
=
546
mg/
kg
(

)
II
870.1200
(
§
81­
2)
Acute
Dermal
42429602
LD50
>
5000
mg/
kg
III
870.1300
(
§
81­
3)
Acute
Inhalation
42429603
LC50
=
1.2
mg/
L.
II
870.2400
(
§
81­
4)
Primary
Eye
Irritation
00070237
non­
irritant
IV
870.2500
(
§
81­
5)
Primary
Dermal
Irritation
42429604
non­
irritant
IV
870.2600
(
§
81­
6)
Dermal
Sensitization
42429605
not
a
sensitizer
­­

Other
Endpoints
of
Concern
The
dimethipin
risk
assessment
team,
identified
toxicological
endpoints
of
concern
for
dimethipin.

All
calculations
completed
in
this
document
are
based
on
the
most
current
toxicity
6
information
available
for
dimethipin.
The
endpoints
that
were
used
to
complete
this
assessment
are
summarized
below
in
Table
2.

Table2:
Summary
of
Toxicological
Doses
and
Endpoints
for
Dimethipin
for
Use
in
Human
Risk
Assessment
Exposure
Scenario
Dose
(
mg/
kg/
day)

UF
/
MOE
Hazard
Based
Special
FQPA
Safety
Factor
Endpoint
for
Risk
Assessment
Incidental
Oral
Short­
and
Intermediate­
Term
Not
required
­
no
residential
uses.
Not
required
­

no
residential
uses.
Not
required
­
no
residential
uses.

Non­
Dietary
Risk
Assessments
Dermal
Short
and
Intermediate­
Term
N/
A
N/
A
No
hazard
was
identified
therefore
no
quantification
is
required.
Systemic
toxicity
not
seen
at
the
limit
dose
in
a
Dermal
Toxicity
Study.
Additionally,
there
are
no
developmental
concerns.

Dermal
Long­
Term
N/
A
N/
A
Based
on
use
pattern,
no
exposure
is
anticipated.

Inhalation
Short­
Term
(
1
­
30
days)
NOAEL
=
20
mg/
kg/
day
Developmental
Study
in
the
Rabbit
LOAEL
=
40
mg/
kg/
day,
based
on
decreased
body
weight
gain.
Occupational
MOE=
100
N/
A
Inhalation
Intermediate­
Term
(
1
­
6
Months)
NOAEL
=
11.8
mg/
kg/
day
Two­
generation
reproduction
study
in
the
rat
LOAEL
=
31.2­
120.3
mg/
kg/
day,
based
on
decreased
body
weight/
body
weight
gain
in
F0
&
F1
females.

Occupational
MOE
=
100
N/
A
Inhalation
Long­
Term
(>
6
Months)
NA
NA
Based
on
use
pattern,
no
exposure
is
anticipated.

Cancer
Classification:
Class
C
(
possible
carcinogen)
calculation
of
a
q1*
was
not
recommended.

1.2
Summary
of
Use
Patterns
and
Formulations
At
this
time,
products
containing
dimethipin
are
intended
for
occupational
use
only.

Type
of
pesticide
Dimethipin
is
a
herbicide
used
for
cotton
and
non­
bearing
apple
defoliation.
Defoliation
is
a
critical
step
in
cotton
production
and
involves
removing
leaves
and
preparing
the
crop
for
mechanical
harvest.
Leaf
removal
facilitates
harvest
and
allows
for
more
efficient
and
faster
picker
operation,
quicker
drying
of
seed
cotton,
straightening
of
lodged
plants,
retardation
of
boll
rot
and
faster
opening
of
green
bolls.
In
many
cases,
chemicals
that
hasten
the
opening
of
green
bolls
and
inhibit
juvenile
regrowth
are
included
with
a
defoliant
(
Leafless
®
)
.
7
Formulation
types
and
percent
active
ingredient
Dimethipin
is
formulated
as
a
manufacturing
product
(
98.0%
active
ingredient),
two
Flowable
concentrate
formulation
(
48.0%
active
ingredient)
and
one
emulsifiable
concentrate
formulation
(
32.7
%
active
ingredient)

Registered
use
sites,
application
rates
and
frequency
of
application
Dimethipin
is
applied
as
a
pre­
harvest,
foliar
and
after
boil­
opening
on
cotton.
It
can
also
be
used
to
defoliate
non­
bearing
apple
nursery
stock
prior
to
digging
or
harvesting.
Dimethipin
can
be
applied
at
a
minimum
application
rate
of
0.077
to
a
maximum
application
rate
of
0.56
pounds
active
ingredient
per
acre.

Table
3
represents
information
on
registered
use
sites,
products
name,
application
rates,
percent
active
ingredient
and
frequency
of
application
per
growing
season
for
dimethipin.
Application
rate
covers
various
type
of
equipment
used
to
apply
dimethipin.

Table
3:
Use
Patterns,
Application
Rate,
and
Frequency
of
Application
for
Dimethipin
Reg
No
ai
%
Product
Name
Crop
Type
Max
Appl
rate
lb
ai/
A
No
of
Appls
per/
year
400­
505
32.7
Leafless
cotton
(
after
boll
opening)
0.31
NS
400­
155
48.0
Harvade­
5F
cotton
(
foliar)
0.31
400­
398
22.4
Harvade­
25F
cotton
(
preharvest)
0.56
WA­
980008
48.0
Harvade­
5F
non­
bearing
apple
(
foliar)
0.077
400­
432
98.00
Harvade
Technical
1.3
Methods
and
Types
of
Equipment
Used
for
Mixing/
Loading/
Applying
The
following
use
patterns
are
associated
with
the
application
equipment:

groundboom,
high
pressure
handwand
and
fixed­
wing
aircraft.

1.4
Incident
reports
On
the
list
of
the
top
200
chemicals
for
which
NPIC
received
calls
from
1984­
1991
inclusively,
dimethipin
was
not
reported
to
be
involved
in
human
incidents.
Relatively
few
incidents
of
illness
have
been
reported
due
to
dimethipin.

2.0
OCCUPATIONAL
EXPOSURES
8
2.1
Handler
Exposures
&
Assumptions
Handler
Exposure
Scenarios
Exposure
scenarios
can
be
thought
of
as
ways
of
categorizing
the
kinds
of
exposures
that
occur
related
to
the
use
of
a
chemical.
The
use
of
scenarios
as
a
basis
for
the
exposure
assessment
is
described
in
the
U.
S.
EPA
Guidelines
For
Exposure
Assessment
(
U.
S.
EPA;
Federal
Register
Volume
57,
Number
104;
May
29,
1992).

HED
uses
the
term
"
Handlers"
to
describe
those
individuals
who
are
involved
in
the
pesticide
application
process.
HED
believes
that
there
are
distinct
job
functions
or
tasks
related
to
applications
and
that
exposures
can
vary
depending
on
the
specifics
of
each
task.
Job
requirements
(
e.
g.,
amount
of
chemical
to
be
used
in
an
application),
the
kinds
of
equipment
used,
the
crop
or
target
being
treated,
and
the
circumstances
of
the
user
(
e.
g.,
the
level
of
protection
used
by
an
applicator)
can
cause
exposure
levels
to
differ
in
a
manner
specific
to
each
scenario.

HED
has
developed
a
series
of
general
descriptions
for
tasks
that
are
associated
with
pesticide
applications.
Tasks
associated
with
pesticide
use
(
i.
e.,
for
"
handlers")
can
generally
be
categorized
using
one
of
the
following
terms:


Occupational
Mixer/
loaders:
these
individuals
perform
tasks
in
preparation
for
an
application.
For
example,
they
would
prepare
dilute
spray
solutions
or
transfer
dilute
spray
solutions
into
application
equipment
such
as
a
groundboom
tractor.


Occupational
Applicators:
these
individuals
operate
application
equipment
during
the
application
of
dimethipin
to
registered
sites.
These
individuals
can
make
applications
using
equipment
such
as
groundboom
sprayers.

HED
has
determined
that
there
are
potential
exposures
to
mixers,
loaders,
applicators,
or
other
handlers
during
usual
use­
patterns
associated
with
dimethipin.
Based
on
the
use
patterns
and
potential
exposures
described
above,
7
major
exposure
scenarios
are
identified
in
this
document
to
represent
the
extent
of
dimethipin
uses
These
scenarios
include:
(
1)
mixing/
loading
liquids
for
aerial
application,
(
2)
mixing/
loading
liquids
for
groundboom
application,
(
3)
mixing/
loading
liquids
for
high­
pressure
handwand,
(
4)
sprays
for
aerial
application,
(
5)
sprays
for
groundboom
application,
(
6)
spray
for
High
pressure
handwand
application
and
(
7)
flagging
for
sprays
application.
9
2.1.1
Summary
of
Uncertainties
The
handler
exposure
assessments
encompass
use
of
dimethipin
throughout
the
country.
It
is
difficult
to
assess
all
of
the
"
typical"
uses
(
i.
e.,
actual
or
predominate
application
rates
and
farm
sizes),
and
therefore,
an
assessment
has
been
developed
that
is
believed
to
be
realistic
and
yet
provides
a
reasonable
certainty
that
the
exposures
are
not
underestimated.
The
assumptions
and
uncertainties
are
identified
below
to
be
used
in
risk
management
decisions:


Application
Rates:
The
application
rates
are
the
maximum
allowable
that
were
identified
on
the
available
product
labels.


Amount
Handled:
The
daily
acres
treated
are
HED
standard
values
(
see
Table
4).

The
values
for
groundboom
applications
in
agriculture
vary.
Groundboom
applications
in
an
agricultural
setting
for
cotton
are
based
on
an
200
acre
day
because
the
Agency
believes
it
would
take
8
hours
to
complete
that
type
of
application
with
common
equipment
and
that
acreage
estimate
for
various
crops
is
reasonable.
For
application
with
fixed­
wing
aircraft
1200
acre
per
day
was
used.
For
application
with
high
pressure
handwand
1000
gallons
/
day
used.

Table
4
presents
the
exposure
scenarios,
application
rates,
and
area
(
i.
e.,
acres
or
gals)
potentially
treated
that
have
been
used
in
the
exposure
calculations.
Dimethipin
labels
include
a
multitude
of
uses
and
a
range
of
application
rates.

Chemical­
specific
data
for
assessing
human
exposures
during
pesticide
handling
activities
were
not
submitted
to
the
Agency
in
support
of
the
reregistration
of
dimethipin.
Consequently
it
is
the
policy
of
the
HED
to
use
data
from
the
Pesticide
Handlers
Exposure
Database
(
PHED)
Version
1.1
to
assess
handler
exposures
for
regulatory
actions
when
chemical­
specific
monitoring
data
are
not
available.

PHED
was
designed
by
a
task
force
of
representatives
from
the
U.
S.
EPA,
Health
Canada,
the
California
Department
of
Pesticide
regulation,
and
member
companies
of
the
American
Crop
Protection
Association.
PHED
is
a
software
system
consisting
of
two
parts
­­
a
database
of
measured
exposure
values
for
workers
involved
in
the
handling
of
pesticides
under
actual
field
conditions
and
a
set
of
computer
algorithms
used
to
subset
and
statistically
summarize
the
selected
data.
Currently,
the
database
contains
values
for
over
1,700
monitored
individuals
(
i.
e.,
replicates)

Users
select
criteria
to
subset
the
PHED
database
to
reflect
the
exposure
scenario
being
evaluated.
The
subsetting
algorithms
in
PHED
are
based
on
the
central
assumption
that
the
magnitude
of
handler
exposures
to
pesticides
are
primarily
a
function
of
activity
(
e.
g.,
mixing/
loading,
applying),
formulation
type
(
e.
g.,
liquid),
application
method
(
e.
g.,
groundboom),
and
clothing
scenarios
(
e.
g.,
gloves).
10
Once
the
data
for
a
given
exposure
scenario
have
been
selected,
the
data
are
normalized
(
i.
e.,
divided
by)
by
the
amount
of
pesticide
handled
resulting
in
standard
unit
exposures
(
milligrams
of
exposure
per
pound
of
active
ingredient
handled).
Following
normalization,
the
data
are
statistically
summarized.
The
distribution
of
exposure
values
for
each
body
part
(
e.
g.,
chest
upper
arm)
is
categorized
as
normal,
lognormal,
or
"
other"
(
i.
e.,
neither
normal
nor
lognormal).
A
central
tendency
value
is
then
selected
from
the
distribution
of
the
exposure
values
for
each
body
part.
These
values
are
the
arithmetic
mean
for
normal
distributions,
the
geometric
mean
for
lognormal
distributions,
and
the
median
for
all
"
other"
distributions.
Once
selected,
the
central
tendency
values
for
each
body
part
are
composited
into
a
"
best
fit"
exposure
value
representing
the
entire
body.

The
unit
exposure
values
calculated
by
PHED
generally
range
from
the
geometric
mean
to
the
median
of
the
selected
data
set.
To
add
consistency
and
quality
control
to
the
values
produced
from
this
system,
the
PHED
Task
Force
has
evaluated
all
data
within
the
system
and
has
developed
a
set
of
grading
criteria
to
characterize
the
quality
of
the
original
study
data.
The
assessment
of
data
quality
is
based
on
the
number
of
observations
and
the
available
quality
control
data.
These
evaluation
criteria
and
the
caveats
specific
to
each
exposure
scenario
are
summarized
in
Table
A3.
While
data
from
PHED
provide
the
best
available
information
on
handler
exposures,
it
should
be
noted
that
some
aspects
of
the
included
studies
(
e.
g.,
duration,
acres
treated,
pounds
of
active
ingredient
handled)
may
not
accurately
represent
labeled
uses
in
all
cases.
HED
has
developed
a
series
of
tables
of
standard
unit
exposure
values
for
many
occupational
scenarios
that
can
be
utilized
to
ensure
consistency
in
exposure
assessments.

Table
4:
Exposure
Variables
for
Uses
of
Dimethipin
Exposure
Scenario
(
Scenario
#)
Crop
Type
Application
Rates
(
lb
ai/
acre
or
gal
)
a
Daily
Acres
or
gals
Treatedb
Mixer/
Loader
Exposure
mixing/
loading
liquids
for
aerial
application
(
1)
Cotton
0.56
1200
mixing/
loading
liquids
for
groundboom
application
(
2)
200
mixing/
loading
liquids
for
High­
pressure
Hand
Wand
(
3)
Apple
0.00077/
gal
1000
gals
Applicator
sprays
for
aerial
application
(
4)
Cotton
0.56
1200
sprays
for
groundboom
application
(
5)
200
Spray
for
High
pressure
Hand
Wand
application
(
6)
Apple
0.00077/
gal
1000
gals
Flagger
flagging
for
sprays
application
(
7)
Cotton
0.56
350
a
Application
rates
are
the
maximum
found
on
dimethipin
labels
b
Daily
acres
or
gallons
treated
are
based
on
HED's
estimates
of
acreage
that
would
be
reasonably
expected
to
be
treated
in
a
single
day
for
each
exposure
scenario
of
concern.
11
2.1.2
Calculation
of
Exposure
Daily
Exposure:
The
daily
inhalation
exposure,
daily
dose
and
hence
the
inhalation
risks,
to
handlers
were
calculated
as
described
below.
The
first
step
was
to
calculate
daily
exposure
(
inhalation)
using
the
following
formula:

Where:
Daily
Inhalation
Exposure
(
mg
ai/
day)
=

Unit
Exposure
(
mg
ai/
lb
ai)
x
Application
Rate
(
lb
ai/
A)
x
Daily
Area
Treated
(
A)

Daily
Exposure
=
Amount
that
is
inhaled,
also
referred
to
as
potential
dose
(
mg
ai/
day);

Unit
Exposure
=
Normalized
exposure
value
derived
from
August
1998
PHED
Surrogate
Exposure
Table.

Application
Rate
=
Normalized
application
rate
based
on
a
logical
unit
treatment,
such
as
acres.
Maximum
value
is
used
(
lb
ai/
A),
and
Daily
Area
Treated
=
Normalized
application
area
based
on
a
logical
unit
treatment
such
as
acres
(
A/
day).

These
calculations
of
potential
daily
inhalation
exposure
to
dimethipin
by
handlers
are
used
to
calculate
the
absorbed
doses
and
total
risk
to
those
handlers.

2.2
Risk
from
Handler
exposure
2.2.1
Calculation
of
Daily
Dose
Using
the
daily
inhalation
exposure
scenarios
identified
in
the
exposure
section,
EPA
calculated
the
potential
risk
to
persons
from
handler
inhalation
exposures
to
dimethipin.

The
daily
inhalation
doses
were
calculated
using
a
60
(
developmental
effect)
kg
body
weight
using
the
following
formulas:

Average
Daily
inhalation
dose
(
mg/
kg/
day)
=
daily
inhalation
exposure(
mg
ai/
day)/
body
weight(
kg)
x
absorption
factor(
100%)

Daily
Exposure
=
Amount
that
is
available
for
inhalation,
also
referred
to
as
potential
dose
(
mg
ai/
day);

Average
Daily
Dose
=
The
amount
as
absorbed
dose
received
from
exposure
to
a
pesticide
in
a
given
scenario
(
mg
pesticide
active
ingredient/
kg
body
weight/
day,
also
referred
to
as
ADD);

Absorption
Factor
=
A
measure
of
the
flux
or
amount
of
chemical
that
crosses
a
biological
boundary
(%
of
the
total
available
absorbed);
and
Body
Weight
=
Body
weight
determined
to
represent
the
population
of
interest
12
(
female)
in
a
risk
assessment
(
60kg).

The
MOEs
were
calculated
using
the
following
formulas:

Inhalation
MOE=
Average
Daily
Inhalation
Dose
(
mg/
kg/
day)/
Inhalation
NOAEL(
mg/
kg/
day)

MOE
=
Margin
of
exposure,
value
used
by
the
Agency
to
represent
risk
or
how
close
a
chemical
exposure
is
to
being
a
concern
(
unitless);

ADD
=
(
Average
Daily
Dose)
or
the
amount
as
absorbed
dose
received
from
exposure
to
a
pesticide
in
a
given
scenario
(
mg
pesticide
active
ingredient/
kg
body
weight/
day);
and
NOAEL
=
Dose
level
in
a
toxicity
study,
where
no
observed
adverse
effects
occurred
(
NOAEL)
in
the
study
or
the
lowest
dose
level
where
an
adverse
effect
occurred.

Handler
exposure
assessments
are
completed
by
EPA
using
a
baseline
exposure
scenario
and,
if
required,
increasing
levels
of
risk
mitigation
(
PPE
and
engineering
controls)
to
achieve
a
margin
of
exposure
of
100
for
dermal
and
inhalation
exposure.
Appendix
A
presents
the
shortterm
and
intermediate
term
MOE
calculations
for
baseline
exposure
and
engineering
control
for
fixed­
wing
aircraft
using
data
from
PHED.

EPA
calculated
the
baseline
MOE
(
short­
term
and
intermediate­
term)
for
each
of
the
exposure
scenarios
using
the
baseline
attire
(
no
respirator).

If
the
baseline
short­
term
or
intermediate­
term
MOE
calculated
using
this
baseline
PPE
was
100
or
greater
(
since
the
NOAEL
is
based
on
data
from
animal
studies)
for
an
exposure
scenario,
then
no
further
calculations
were
made.

Because
of
the
insufficient
number
of
data
points
for
fixed­
wing,
open­
cockpit
aircraft
in
the
PHED,
these
data
should
not
be
used
either
as
a
subset,
or
in
combination
with
data
from
fixed­
wing,
closed­
cockpit
aircraft.
Therefore
HED
calculated
the
short­
term
and
intermediateterm
inhalation
MOE
for
fixed­
wing
aircraft
scenario
with
closed­
cockpit
(
i.
e.,
engineering
control.)

2.2.2
Summary
of
Handler
Risks
Table
5
summarizes
the
numeric
MOE
values
for
both
the
short­
and
intermediate­
term
inhalation
exposure
durations.
The
MOEs
are
presented
for
baseline
and
engineering
controls
(
engineering
controls
assessment
is
for
fixed
wing
aircraft
only).

The
results
of
the
short
and
intermediate­
term
handler
inhalation
assessments
indicate
that
13
all
potential
exposure
scenarios
provide
MOE(
s)
greater
than
100
at
either
the
baseline
(
i.
e.,
no
respirator)
using
open
systems
or
using
engineering
controls
(
i.
e.,
closed
systems
for
fixed
wing
aircraft).
In
total,
14
MOEs
were
calculated
for
the
maximum
application
rate.

Table
5:
Summary
of
Occupational
Handler
Risk
for
Dimethipin
Exposure
Scenario
(
Scenario
#)
Crop
Application
Rate
lb
ai/
A
Daily
Area
Treated
A
or
gal/
day
Short­
Term
Inhalation
MOE
Intermediate­
Term
Inhalation
MOE
Mixer/
Loader
Mixing/
Loading
Liquids
for
Aerial
application
(
1)
Cotton
0.56
1200
1500
880
Mixing/
Loading
Liquids
for
Groundboom
application
(
2)
200
8900
5300
mixing/
loading
liquids
for
Highpressure
Hand
Wand
(
3)
Apple
0.00077/
gal
1000
gals
1300000
770000
Applicator
Sprays
for
Aerial
application
(
4)
Cotton
0.56
1200
26000
(
engineerin
g
control)
15000
(
engineering
control)

Sprays
for
Groundboom
application
(
5)
200
14000
8500
Spray
for
High
pressure
Hand
Wand
application
(
6)
Apple
0.00077/
gal
1000
gals
20000
12000
Flagger
Flagging
for
Sprays
application
(
7)
Cotton
0.56
350
17000
10000
14
3.0
POSTAPPLICATION
EXPOSURES
EPA
did
not
assess
occupational
postapplication
risks
to
agricultural
workers
following
treatments
to
cotton
or
non­
bearing
apple
nursery
stock.,
since
no
short­
or
intermediate­
term
dermal
endpoint
of
concern
was
identified
and
long­
term
dermal
exposures
are
not
expected
for
tasks
involving
cotton
or
apple
use
patterns.
The
toxicity
categories
of
the
active
ingredient
for
acute
dermal,
eye
irritation,
and
skin
irritation
potential
are
used
to
determine
the
interim
REI
(
Restricted­
entry
Intervals).
The
acute
toxicity
classification
for
dermal
irritation
of
dimethipin
is
tox
category
III
which
requires
a
12­
hour
REI.
15
APPENDIX
A
SHORT­
TERM
AND
INTERMEDIATE­
TERM
HANDLER
EXPOSURE
RISK
TABLES
A1
THROUGH
A3
16
Table
A1:
Short
Term
Inhalation
risk
for
occupational
Handler
with
Dimethipin
at
Baseline
Exposure
Scenario
(
Scenario
#)
Inhalation
Unit
Exposure
(
Ug/
lb
ai)
1
Crop2
Application
Rate3
lb
ai/
A
or
gal
Daily
Area
Treated4
A
or
gals/
day
Inhalation
Dose
(
mg/
kg/
day)
5
Inhalation
MOE6
Mixer/
Loader
Mixing/
Loading
Liquids
for
Aerial
application
(
1)
1.2
Cotton
0.56
1200
0.013
1500
Mixing/
Loading
Liquids
for
Groundboom
application
(
2)
200
0.0022
8900
mixing/
loading
liquids
for
High­
pressure
Hand
Wand
(
3)
1.2
Apple
0.00077
/
gal
1000
gals
0.000015
1300000
Applicator
Sprays
for
Aerial
application
(
4)
0.068
(
engineering
control)
Cotton
0.56
1200
0.00076
(
engineering
control)
26000
(
engineering
control)

Sprays
for
Groundboom
application
(
5)
0.74
200
0.0014
14000
Spray
for
High
pressure
Hand
Wand
application
(
6)
79
Apple
0.00077
/
gal
1000
gals
0.0010
20000
Flagger
Flagging
for
Sprays
application
(
7)
0.35
Cotton
0.56
350
0.0011
17000
1Baseline
or
Engineering
Control
inhalation
unit
exposures
represent
no
respirator.
Values
are
reported
in
the
PHED
Surrogate
Exposure
Guide
dated
August
1998
2Crops
and
use
patterns
are
from
Dimethipin
labels
and
LUIS
report
3Application
rates
are
based
on
maximum
values
found
in
various
sources
including
LUIS
and
various
labels.
Application
rates
upon
which
the
analysis
is
based
are
presented
as
lb
ai/
A
or
lb
ai/
gal.

4Amount
treated
is
based
on
the
area
that
can
be
reasonably
applied
in
a
single
day
for
each
exposure
scenario
of
concern
based
on
the
application
method
and
formulation/
packaging
type.
(
Standard
EPA/
OPP/
HED
values).

5Inhalation
dose
(
mg/
kg/
day)
=
[
unit
exposure
(
ug/
lb
ai)
*
0.001
mg/
g
unit
conversion
*
Inhalation
absorption
(
100%)
*
Application
rate
(
lb
ai/
acre
or
lb
ai/
gal
)
*
Daily
area
treated
(
acres
or
gals
)]
/
Body
weight
(
60
kg).

6Inhalation
MOE
=
inhalation
NOAEL
(
20
mg/
kg/
day)
/
Daily
Inhalation
Dose.
Target
Inhalation
MOE
is
100.
17
Table
A2:
Intermediate
Term
Inhalation
risk
for
occupational
Handler
with
Dimethipin
Exposure
Scenario
(
Scenario
#)
Inhalation
Unit
Exposure
(
Ug/
lb
ai)
1
Crop2
Applica
tion
Rate3
lb
ai/
A
or
gals
Daily
Area
Treated
4
A
or
gals/
day
Inhalatio
n
Dose
(
mg/
kg/
d
ay)
5
Inhalati
on
MOE6
Mixer/
Loader
Mixing/
Loading
Liquids
for
Aerial
application
(
1)
1.2
Cotton
0.56
1200
0.013
880
Mixing/
Loading
Liquids
for
Groundboom
application
(
2)
200
0.0022
5300
mixing/
loading
liquids
for
Highpressure
Hand
Wand
(
3)
1.2
Apple
0.00077/
gal
1000
gals
0.000015
770000
Applicator
Sprays
for
Aerial
application
(
4)
0.068
(
engineering
control)
Cotton
0.56
1200
0.00076
(
engineer
ing
control)
15000
(
enginee
ring
control)

Sprays
for
Groundboom
application
(
5)
0.74
200
0.0014
8500
Spray
for
High
pressure
Hand
Wand
application
(
6)
79
Apple
0.00077/
gal
1000
gals
0.0010
12000
Flagger
Flagging
for
Sprays
application
(
7)
0.35
Cotton
0.56
350
0.0011
10000
1Baseline
or
Engineering
Control
inhalation
unit
exposures
represent
no
respirator.
Values
are
reported
in
the
PHED
Surrogate
Exposure
Guide
dated
August
1998
2Crops
and
use
patterns
are
from
Dimethipin
labels
and
LUIS
report
3Application
rates
are
based
on
maximum
values
found
in
various
sources
including
LUIS
and
various
labels.
Application
rates
upon
which
the
analysis
is
based
are
presented
as
lb
ai/
Aor
gal.

4Amount
treated
is
based
on
the
area
that
can
be
reasonably
applied
in
a
single
day
for
each
exposure
scenario
of
concern
based
on
the
application
method
and
formulation/
packaging
type.
(
Standard
EPA/
OPP/
HED
values).

5Inhalation
dose
(
mg/
kg/
day)
=
[
unit
exposure
(
ug/
lb
ai)
*
0.001
mg/
g
unit
conversion
*
Inhalation
absorption
(
100%)
*
Application
rate
(
lb
ai/
acre
or
gals
)
*
Daily
area
treated
(
acres
or
gals
)]
/
Body
weight
(
60
kg).

6Inhalation
MOE
=
inhalation
NOAEL
(
11.8
mg/
kg/
day)
/
Daily
Inhalation
Dose.
Target
Inhalation
MOE
is
100
18
Table
A3:
Sources
of
Exposure
Data
Used
In
The
Short­
and
Intermediate­
Term
Occupational
Dimethipin
Handler
Exposure
And
Risk
calculation
Exposure
Scenario
(
Number)
Data
Source
Standard
Assumptions
(
8­
hr
work
day)
Comments
Mixer/
Loader
Descriptors
Mixing/
Loading
Liquid
Formulations
(
1
through
3)
PHED
V1.1
Aerial:
1200
acres
for
cotton
Groundboom:
200
acres
High
Pressure
Handwand:
1000
gals
Baseline:
Inhalation
=
85
replicates.
High
confidence
in
inhalation
data.

Applying
Descriptors
Applying
Sprays
with
a
Fixed­
wing
Aircraft
(
4)
PHED
V1.1
1200
acres
Engineering
Controls:
inhalation
=
ABC
grade.
Inhalation
=
23
replicates.
Medium
confidence
in
inhalation
data.
No
protection
factor
was
needed
to
define
the
unit
exposure
value.
EPA
has
no
data
for
this
scenario,
other
than
enclosed
cockpits
B
the
engineering
control.

Applying
Sprays
with
a
Groundboom
Sprayer
(
5)
PHED
V1.1
200
acres
Baseline:
Inhalation
=
acceptable
grades.
inhalation
=
22
replicates.

High
confidence
in
inhalation
data.

Liquids
Using
a
High
Pressure
Handwand
(
6)
PHED
V1.1
1,000
gallons
Baseline:
Inhalation
(
13
replicates)
exposure
values
are
based
on
A
grade
data.

Low
confidence
in
inhalation
data.

Flagging
Descriptors
Flagging
Aerial
Spray
Applications
(
6)
PHED
V1.1
350
acres
Baseline:
inhalation
=
acceptable
grades.
inhalation
=
28
replicates.

High
confidence
in
inhalation
data.

a
All
Standard
Assumptions
are
based
on
a
typical
work
day
(
the
components
that
involve
pesticide
use)
as
estimated
by
HED.

b
All
handler
exposure
assessments
in
this
document
are
based
on
the
"
Best
Available"
data
as
defined
by
the
PHED
SOP
for
meeting
Subdivision
U
Guidelines
(
i.
e.,
completing
exposure
assessments).
Best
available
grades
are
assigned
to
data
as
follows:
matrices
with
A
and
B
grade
data
(
i.
e.,
Acceptable
Grade
Data)
and
a
minimum
of
15
replicates;
if
not
available,
then
grades
A,
B
and
C
data
and
a
minimum
of
15
replicates;
if
not
available,
then
all
data
regardless
of
the
quality
(
i.
e.,
All
Grade
Data)
and
number
of
replicates.
Generic
data
confidence
categories
are
assigned
as
follows:

High
=
grades
A
and
B
and
15
or
more
replicates
per
body
part
Medium
=
grades
A,
B,
and
C
and
15
or
more
replicates
per
body
part
Low
=
grades
A,
B,
C,
D
and
E
or
any
combination
of
grades
with
less
than
15
replicates.