
Page
1
of
19
UNITED
STATES
ENVIRONMENTAL
PROTECTION
AGENCY
Washington,
DC
20460
OFFICE
OF
PREVENTION,
PESTICIDES
AND
TOXIC
SUBSTANCES
M
EMORANDUM
DATE:
4/
14/
06
SUBJECT:
Human
Studies
Review
Board:
CARBOFURAN
Weight­
of­
the­
Evidence
Presentation
of
Human
and
Animal
Toxicity
Studies
PC
Code:
090601
FROM:
John
J.
Liccione,
Toxicologist/
Risk
Assessor
Reregistration
Branch
3
Health
Effects
Division
(
7509C)

THRU:
Danette
Drew,
Branch
Senior
Scientist
Reregistration
Branch
3
Health
Effects
Division
(
7509C)

TO:
Tina
Levine,
Director
Health
Effects
Division
(
7509C)

The
purpose
of
this
weight­
of­
evidence
(
WOE)
report
is
to
present
the
study
design,
methods,
and
results
of
three
different
human
studies
to
the
Human
Studies
Review
Board
(
HSRB)
to
evaluate
them
individually
and
collectively
for
their
scientific
validity.
The
human
studies
that
will
be
presented
are
a
single
oral
dose
study
and
two
single
dose
dermal
studies.
Relevant
animal
data
are
also
summarized
and
conclusions
as
to
how
the
Office
of
Pesticide
Programs
(
OPP)
Health
Effects
Division
(
HED)
proposes
to
use
these
data
in
both
the
single
chemical
assessment
and
the
N­
methyl
carbamate
cumulative
assessments
are
presented.

Introduction
Carbofuran
(
2,3­
dihydro­
2,2­
dimethyl­
7­
benzofuranyl­
N­
methylcarbamate)
is
a
broad
spectrum
Nmethyl
carbamate
(
see
structure
below)
is
an
insecticide
that
can
cause
cholinergic
toxicity
through
inhibition
of
the
acetylcholinesterase(
s)
of
the
peripheral
and/
or
central
nervous
system.
Similar
to
other
N­
methyl
carbamate
pesticides,
inhibition
is
followed
by
rapid
recovery
of
acetylcholinesterase.
Animal
toxicity
studies
(
dog,
rat,
mouse)
using
both
acute
and
chronic
exposure
conditions
show
that
the
primary
toxicologic
effect
following
carbofuran
exposure
by
the
oral
route
is
cholinesterase
(
ChE)
activity
inhibition,
the
most
sensitive
endpoint.
Due
to
the
rapid
recovery
of
the
inhibition,
results
of
chronic
studies
in
the
dog,
rat,
and
mouse
indicate
that
the
effects
of
carbofuran
do
not
accumulate
over
time
Page
2
of
19
Several
toxicity
studies
involving
direct
dosing
of
humans
with
carbofuran
(
including
both
the
oral
and
dermal
routes
of
exposure)
have
been
conducted.
ChE
inhibition
and
associated
clinical
signs
have
been
demonstrated
in
the
submitted
human
volunteer
studies.

TOXICITY
STUDIES
HUMAN
1)
Human
Single­
Dose
Oral
Study:

Arnold,
J.
D.
(
1976)
Evaluation
of
the
Safe
Exposure
Levels
to
Carbamate,
Administered
Orally
to
Healthy
Adult
Normal
Male
Volunteers.
(
Unpublished
study
received
Oct
24,
1979
under
279­
2712;
prepared
by
Quincy
Research
Center,
submitted
by
FMC
Corp.,
Philadelphia,
Pa.;
CDL:
241303­
B)
Accession
no.
241303.
MRID
00092826.

Study
Description
Laboratory:
Quincy
Research
Center,
Kansas
City,
MO
Study
Dates:
Not
reported;
study
report
is
dated
9/
17/
1976
Purpose
of
Study:
"
To
determine
the
threshold
toxicity
level
in
normal
male
volunteers
to
single
oral
doses
of
carbamate."

General
design:
The
protocol
for
this
study
called
for
an
ascending
dose
schedule
with
the
following
doses:
0.05,
0.1,
0.25,
0.50,
1.0,
and
2.0
mg/
kg.
Part
A
was
an
"
open"
experiment
(
assumed
to
mean
that
both
investigator
and
subject
were
aware
that
carbofuran
was
being
ingested)
that
started
with
two
subjects
each
receiving
0.05
mg/
kg
carbofuran
with
no
placebo
group.
If
no
toxicity
was
observed
after
24
hours,
two
more
subjects
were
then
given
the
next
dose,
and
this
was
repeated
until
"
intolerance
was
demonstrated".
Then
Part
B
of
the
experiment
was
performed
in
which
one
subject
received
a
placebo
and
two
subjects
received
the
highest
(
i.
e.,
intolerable)
dose
observed
in
Part
A.
In
Part
B,
the
design
was
both
randomized
and
double
blind.
Table
1
shows
the
study
design
up
to
the
dose
considered
intolerable.

Subjects
were
admitted
to
the
Quincy
Research
Ctr.
by
4
pm
the
evening
before
the
study
began,
and
were
dosed
the
following
morning
after
a
standard
breakfast.
According
to
the
protocol,
the
placebo
and
carbofuran
capsules
were
provided
by
the
Midwest
Research
Institute
[
MRI],
but
how
they
were
consumed
by
the
subjects
is
not
recorded.
The
volunteers
were
confined
to
their
beds
from
Page
3
of
19
0
hour
to
2
hrs
post­
dosing,
and
were
permitted
only
minor
ambulatory
activity
from
2
hours
to
8
hours
post­
dosing.
The
subjects
remained
under
observation
for
24
hours,
and
were
permitted
no
alcohol
or
concomitant
medications
during
the
course
of
the
study.
When
the
observation
period
ended,
the
pre­
entry
physical
examinations
and
laboratory
determinations
were
repeated
and
the
subjects
released
from
the
center.
Cigarette
smoking
was
permitted
during
the
study
(
2
of
the
4
high­
dose
subjects
were
the
only
non­
smokers).

Subjects:
Nine
healthy
men
"
who
fulfilled
the
selection
criteria
were
selected
to
participate
in
the
study."
No
information
was
provided
about
how
or
from
what
pool
they
were
recruited.
The
age
and
body
weight
ranges
were
23­
47
and
60­
95
kg,
respectively.

.

Table
1:
Single
Oral
Dose
Study
Design
Dose
(
mg/
kg)
Study
Phase
(
Session)
Control
0.05
0.1
0.25
(
1)
2
 
 

(
2)
 
2
 
P
a
r
t
A
(
3)
None
 
 
2
Part
B
1
 
 
2
Measures:
RBC
and
Plasma
cholinesterase
activity
(
0 
hour/
pre­
dosing,
and
then
30
min.,
1,
2,
3,
6
,
and
24
hrs
post­
dosing);
EKG,
blood
pressure,
heart
rate,
temperature,
respiration,
vestibular
function,
pupil
size,
eye
accommodation,
hematology,
urinalysis
and
blood
chemistry
were
measured
at
pre­
dosing
and
at
various
intervals
up
to
24
hours
after
dosing.
During
the
observation
period
(
24
hours)
subjects
were
monitored
for
signs
or
symptoms
of
toxicity.
The
next
highest
dosing
was
not
initiated
until
data
from
the
24­
hour
post
treatment
were
evaluated.

The
cholinesterase
assay
used
in
this
study
(
Voss
and
Sachsse,
1970)
was
a
modification
of
the
Ellman
colorimetric
method.
This
method
uses
propionylthiocholine
rather
than
acetylthiocholine
as
the
substrate
in
the
assay.
According
to
the
abstract
(
see
Appendix
1),
this
method
was
developed
to
assess
cholinesterase
activities
in
humans
when
a
small
volume
of
blood
is
collected
for
analysis.

Analysis:
There
was
no
statistical
analysis
of
the
data.

Study
Results
Page
4
of
19
Table
2
summarizes
the
results
of
the
study.
The
lowest
dose
tested
(
0.05
mg/
kg)
resulted
in
minimal
RBC
ChEI
with
no
symptoms
being
reported.
The
second
and
third
doses,
however,
showed
a
marked
decrease
in
RBC
ChEI
and
in
symptoms
(
both
subjective
and
objective)
in
a
dose­
related
manner.
The
third
dose
(
0.25
mg/
kg)
was
considered
an
"
intolerable"
dose
in
the
first
two
subjects
tested
and
so
was
tested
in
another
two
subjects
as
Part
B
of
the
experiment,
along
with
a
single
control
subject.
Appendix
2
provides
the
individual
RBC
ChEI
values
(
in
terms
of
percent
change
from
baseline)
for
each
subject
at
each
time
point
(
from
pre­
dose
to
24
hours).
The
data
show
both
the
decrease
in
RBC
at
the
1­
3
hour
post­
dosing
time
period
and
the
eventual
return
to
"
normal"
values.
Plasma
ChEI
values
are
not
presented
in
Appendix
2
as
they
were
more
variable
and
the
RBC
ChEI
is
considered
more
important
as
a
marker
for
carbofuran
exposure.

I
t
should
be
noted
that
EPA
performed
a
benchmark
(
BMD)
analysis
of
this
human
data
as
part
of
the
Nmethyl
cumulative
assessment
and
calculated
a
BMDL10
of
0.026
mg/
kg
(
BMD10
of
0.039
mg/
kg).

Table
2:
Results
of
Single
Oral
Human
Study
with
Carbofuran
Dose
RBC
ChEI
1
Plasma
ChEI
Symptoms
Control
10%
54%

0.05
mg/
kg
11%,
22%
2
32%,
36%
No
symptoms
noted.

0.1
mg/
kg
33%,
31%
2
56%,
35%
Headache
(
1
subject);
lightheadedness
(
the
other
subject).
One
subject
had
EKG
anomalies
(
25%
decrease
in
sinus
rate,
sinus
arrhythmia,
and
sinus
bradycardia
 
all
at
4
hr
and
24
hr
post­
treatment
time
points).
Same
subject
showed
deterioration
in
vestibular
mechanism
(
but
baseline
was
already
abnormal
and
the
subject
was
a
smoker).

0.25
mg/
kg
46%,
63%,
62%,
59%
3
33%,
100%,
53%,
81%
Symptoms
usually
attributed
to
cholinesterase
inhibition
(
drowsiness,
nausea,
dizziness,
nervousness,
vomiting,
headache,
weakness,
dry
mouth,
salivation,
unsteadiness
4
,
abdominal
pains,
and
diaphoresis)
were
seen
in
3
of
4
subjects
within
3
hrs
of
dosing.
The
fourth
exhibited
nausea
within
a
30
min.
of
dosing.
Three
of
the
subjects
had
changes
in
heart
rate,
lower
body
temperature,
and
lower
respiration
rates.
EKG
results
showed
anomalies
in
three
subjects
(
sinus
bradycardia,
25%
decrease
in
sinus
rate)
 
one
subject
did
not
recover
by
the
end
of
the
monitoring
period
(
24
hrs).
1
Percent
decrease
provided
for
each
individual
subject
on
study.
Maximum
inhibition
presented
for
all
subjects.
2
Seen
at
1­
hr;
almost
returned
to
normal
by
3
hr
in
all
subjects.
3
Seen
at
1
[
one
subject]
and
3
[
three
subjects]
hrs
post
dosing;
almost
returned
to
normal
by
six
hrs.
4
Vestibular
mechanisms
for
2/
4
were
abnormal
and
deteriorating
one
hr.
post­
dosing.
One
of
these
subjects
could
not
stand
up
after
one
hour
postdosing

Strengths/
Uncertainties/
Limitations
The
following
strengths
of
the
single
dose
oral
study
in
male
human
volunteers
have
been
identified:

 
Effects
were
observed
in
the
treated
subjects
(
in
terms
of
both
subjective
and
objective
measures).
 
Multiple
doses
were
used.
Page
5
of
19
 
All
subjects
were
monitored
(
they
were
kept
at
the
center
from
the
night
before
dosing
up
to
24
hours
after
dosing).
 
The
ChEI
effects
observed
(
and
associated
symptoms)
occurred
at
or
about
the
expected
peak
time
(
1­
3
hours
post­
dosing)
and
returned
to
almost
normal
within
six
hours
of
dosing.

The
following
uncertainties/
limitations
have
also
been
identified:

 
There
was
no
discussion
of
the
rationale
for
dose
selection.
 
The
number
of
subjects
is
low
(
2
subjects)
for
the
low­
(
0.05
mg/
kg)
and
mid­
dose
(
0.1
mg/
kg)
groups,
and
a
placebo
(
with
only
one
subject)
was
only
used
in
Part
B
of
the
experiment.
 
All
tested
subjects
were
males.
 
There
was
no
statistical
analysis.
 
Part
A
was
"
open"
 
assumed
to
mean
that
both
the
investigator
and
subject
were
aware
that
the
subject(
s)
were
receiving
the
treatment
capsule.
 
There
was
potential
confounding
due
to
smoking
(
all
except
two
subjects
 
both
in
the
0.25
mg/
kg
group
 
smoked).
See
Appendix
2
for
number
of
cigarettes
consumed
by
each
subject
during
the
study.
 
Duplicate
blood
samples
were
taken
to
analyze
for
carbofuran
and/
or
its
metabolites
but
the
data
have
not
been
submitted.
 
The
RBC/
plasma
ChEI
method
used
was
a
different
method
than
what
is
normally
used.
The
study
report
is
dated
1976
and
it
is
assumed
that
the
study
was
performed
around
that
time.
The
method
paper
was
published
in
1970
(
Voss,
G.
and
Sachsse,
1970).
The
Ellman
method
was
published
in
1961.
 
No
justification
or
rationale
of
dose
selection
Conclusions
The
study
authors
considered
the
dose
level
of
0.1
mg/
kg
as
a
"
NOEL"
whereas
the
OPP
has
considered
the
dose
level
of
0.1
mg/
kg
as
a
"
LOEL"
in
the
past
1
.

There
is
some
confidence
in
the
high
dose
(
0.25
mg/
kg)
as
a
definitive
effect
level.
Although
there
may
be
potential
confounding
due
to
smoking,
this
dose
level
had
4
subjects
that
demonstrated
clear
symptoms
of
cholinesterase
toxicity,
and
moreover,
the
symptoms
could
be
correlated
in
their
severity
and
incidence
with
the
extent
and
duration
of
RBC
ChEI.
Effects
consisted
of
drowsiness,
nausea,
dizziness,
nervousness,
vomiting,
headaches,
weakness,
dry
mouth,
salivation,
unsteadiness,
abdominal
pains,
and
diaphoresis.
Changes
in
heart
rate,
lower
body
temperatures,
and
lower
respiration
rate
were
also
noted
in
these
subjects.
There
were
also
effects
on
EKG,
vestibular
mechanisms,
pupillary
constriction
and
eye
accommodation.

At
the
0.1
mg/
kg
dose
level,
one
subject
had
a
headache,
and
the
other
was
occasionally
lightheaded.
The
study
authors
did
not
consider
the
headache
and
lightheadedness
to
be
compound
related.
One
subject
exhibited
a
decrease
in
sinus
rate.
This
subject
also
exhibited
deterioration
in
the
vestibular
mechanism;
although
the
baseline
value
for
this
parameter
was
abnormal
to
begin
with.
In
addition,
the
one
concurrent
control
in
the
second
round
of
testing
at
0.25
mg/
kg
displayed
decreased
sinus
rate
and
erratic
vestibular
function
(
at
baseline
it
was
borderline
between
normal
and
abnormal,
and
at
various
time
intervals
was
reported
as
abnormal
and
deteriorating).
Therefore,
the
sinus
rate
and
vestibular
function
effects
are
difficult
to
assess.

Using
the
BMD
calculation,
the
BMDL10
of
0.026
mg/
kg
is
a
reasonable
Point
of
Departure
(
PoD)
for
possible
use
in
risk
assessment.

1
In
1997,
OPP
requested
an
external
peer
review
of
this
carbofuran
study.
Three
academic
scientists
reviewed
the
study
and
determined
it
was
an
appropriate
study
to
use
to
develop
an
RfD
and
also
commented
on
the
use
of
uncertainty
factors
in
deriving
an
RfD
(
Burnam,
1970).
Page
6
of
19
2)
Human
Dermal
Study:

A
rnold,
J.
D.
(
1977)
Carbamate
(
Carbofuran)
Human
Dermal
Study.
Final
rept.
(
Unpublished
study
received
Oct
24,
1979
under
279­
2712;
prepared
by
Quincy
Research
Center,
submitted
by
FMC
Corp.,
Philadelphia,
Pa.;
CDL:
241303­
C),
Accession
no.
241303.
MRID
00092827.

Study
Description
Laboratory:
Quincy
Research
Center,
Kansas
City,
MO
Study
Dates:
Not
reported;
study
report
is
dated
1977.

Purpose
of
Study:
"
To
determine
the
threshold
toxicity
level
to
simple
and
multiple
doses
of
Carbofuran
under
normal
and
elevated
temperatures
and/
or
humidities"

General
design:
Like
the
single
oral
dose
study
described
above,
this
dermal
study
was
designed
as
an
ascending
dose
study.
The
protocol
proposed
to
begin
with
a
dose
of
0.5
mg/
kg,
with
dosing
increasing
in
multiples
of
two
up
to
16
mg/
kg
(
note
that
the
study
went
up
to
32
mg/
kg)
until
the
"
minimum
effect
level"
is
reached.
The
minimum
effect
level
is
defined
as
" 
the
level
which
produces
mild
but
definitive
clinical
symptoms,
as
observed
in
the
oral
studies."
After
a
standard
breakfast,
volunteers
were
dermally
dosed
with
a
50%
test
article
dilution
(
undiluted
test
substance:
Furadan
75
WP;
75%
carbofuran)
on
a
designated
portion
of
their
upper
backs
2
,
mildly
exercised
for
5
minutes,
then
allowed
to
rest
for
15
minutes.
This
cycle
was
repeated
11
times
over
4
hours.
After
four
hours,
the
carbofuran
was
removed/
washed
from
the
back.
With
each
cycle,
the
dose
was
doubled
until
a
"
minimum
effect
level"
was
attained.
After
the
4
hour
dosing
interval,
the
dosages
were
removed
and
subjects
monitored
for
the
remainder
of
the
24
hour
post­
treatment
period.
Cigarette
smoking
was
permitted
during
the
study
Subjects:
Eighteen
healthy
males
(
19­
53
years
of
age)
were
chosen
with
a
weight
range
of
63­
102
kg.

Numbers/
Doses:
This
study
was
performed
in
three
parts 
A,
B,
and
C.
Eight
subjects
were
assigned
to
part
A,
eight
subjects
were
assigned
to
part
B,
and
two
subjects
were
assigned
to
part
C
(
see
Table
3
below).
Escalating
doses
were
used
in
parts
A
(
0,
0.5,
1.0,
and
2.0
mg
ai/
kg)
and
B
(
2.0,
4.0,
8.0,
and
32.0
mg
ai/
kg)
over
the
course
of
one
day
(
2
subjects
per
dose
level;
single
dermal
dose)
using
high
temperature/
high
humidity
(
85­
95
degrees
F
and
68­
89%
relative
humidity)
in
Part
A
and
normal
temperature/
normal
humidity
(
70­
75
degrees
F
and
35­
40%
relative
humidity)
in
Part
B.
Part
C
consisted
of
treating
two
test
subjects
once
daily
at
1.0
mg
ai/
kg/
day
on
three
consecutive
days
(
multiple
dermal
doses)
under
the
same
high
temperature/
high
humidity
conditions
identified
above
for
Part
A.

Table
3:
Acute
Dermal
Study
Design
(
Arnold,
1977)

Dose
(
mg/
kg)
Study
Phase
(
Session)
Control
0.5
1.0
2.0
4.0
8.0
32.0
2
The
submitted
report
is
unreadable
regarding
specifics
on
this
procedure
(
see
page
113
in
the
electronic
copy
of
Accsn241303,
also
labeled
as
page
129
on
the
bottom
right
hand
corner
of
the
page).
Page
7
of
19
A
1
2
2
2
2
­
­
­

B
2
­
 
­
2
2
2
2
C
1
­
 
2
­
­
­
­

1
High
temperature/
high
humidity
conditions.

2
Normal
temperature/
normal
humidity
conditions.

Measures:
RBC
and
Plasma
cholinesterase
activity
(
0 
hour/
pre­
dosing,
1,
2,
3,
6
,
and
24
hours);
EKG,
blood
pressure,
heart
rate,
temperature,
respiration,
vestibular
function,
pupil
size,
eye
accommodation,
hematology
and
urinalysis
were
measured
at
pre­
dosing
and
at
various
intervals
up
to
24
hours
after
dosing.
During
the
observation
period
(
24
hours)
subjects
were
monitored
for
clinical
signs.
As
noted
above
for
the
oral
study,
the
Voss
and
Sachsse
method
for
ChEI
determination
was
used.

Analysis:
There
was
no
statistical
analysis
of
the
data.

Study
Results
Tables
4­
6
show
the
results
from
Parts
A,
B,
and
C;
respectively.
RBC
Cholinesterase
inhibition
was
compared
to
the
self
pre­
dose
measurement.
The
subjects
given
the
high
dose
of
2
mg/
kg
in
Part
A
were
the
only
ones
from
any
of
the
three
experiments
that
showed
both
appreciable
decreases
in
RBC
ChEI
and
symptoms
generally
associated
with
a
cholinergic
response.
Because
this
exposure
scenario
was
under
high
heat/
high
humidity
conditions,
it
is
likely
that
this
contributed
to
the
enhanced
absorption
and
associated
toxicity.
This
can
be
inferred
given
that
the
results
of
the
same
experiment
performed
under
normal
heat/
humidity
conditions
(
Part
B)
using
much
higher
doses
(
up
to
32
mg/
kg)
showed
no
effects.
The
three­
day
dosing
experiment
summarized
in
Table
3
was
inconclusive
since
there
were
no
effects
and
no
controls.
In
all
three
experiments,
male
volunteers
were
required
to
perform
mild
exercise
activities
which
could
be
seen
as
enhancing
the
possible
dermal
absorption
and
possible
toxicity
of
carbofuran.
Page
8
of
19
Table
4:
Results
of
Dermal
Human
Study
(
Arnold,
1977)
with
Carbofuran:
Part
A
1
Dose
RBC
ChEI
2
Plasma
ChEI
2
Symptoms
Control
10%,
10%
0,
25%

0.5
mg/
kg
20%,
23%
(
both
@
3
hrs.)
10%,
10%
(@
6
and
3
hrs)

1.0
mg/
kg
39%,
9%
(@
3
and
1
hrs)
5%,
11%
(
both
@
3
hrs)
No
symptoms
noted.

2.0
mg/
kg
46%,
65%
(
both
@
4
hrs)
12%,
16%
(
both
@
24
hrs)
One
subject
(
46%
peak
RBC
ChEI)
reported
feeling
weak
and
shaky
3
hrs,
30
min.
postdosing
and
was
administered
atropine
at
5
hrs
post­
dose.
The
other
subject
had
more
severe
symptoms
(
lightheadedness,
hazy
vision,
hunger,
vomiting,
defecation
with
muscular
cramps,
chills)
from
2
hrs,
30
min.
to
4
hrs
post
dosing.
Atropine
was
administered
at
three
different
times
(
4
hrs
20
min,
5
hrs,
5
min;
and
5
hrs,
15
min.
post­
dosing.
The
carbofuran
solution
was
washed
off
his
back
prior
to
atropine
administration.
Both
subjects
had
changes
in
pulse
and
vestibular
function.
EKGs
were
normal
and
pupil
size/
accommodation
measurements
could
not
be
made.
Both
subjects
were
asymptomatic
at
24
hrs
postdosing
1
Single
dose
of
carbofuran
applied
to
backs
of
volunteers.
Subjects
were
placed
in
an
enclosed
environment
with
high
temperature/
high
humidity
conditions
one
hour
before
dosing
and
then
for
four
hours
post­
dosing.
During
the
four
hour
exposure
period,
they
exercised
for
5
minutes,
rested
for
15
minutes
and
then
continued
this
cycle
11
times.
2
Percent
decrease
provided
for
each
individual.
Maximum
inhibition
presented
for
all
individuals
and
the
time
point
associated
with
that
maximum.
Page
9
of
19
Table
5:
Results
of
Dermal
Human
Study
(
Arnold,
1977)
with
Carbofuran:
Part
B
1
Dose
RBC
ChEI
2
Plasma
ChEI
2
Symptoms
2.0
mg/
kg
10%,
20%
(
both
@
6
hrs.)
6%,
5%
(@
6
and
3
hrs)

4.0
mg/
kg
13%,
11%
(@
6
and
2
hrs.)
26%,
33%
(
both
@
2
hrs)

8.0
mg/
kg
7%,
17%
(@
3
and
6
hrs)
+
7%,
4%
(@
3
and
1/
6
hrs)

32.0
mg/
kg
24%,
16%
(@
8
and
4
hrs)
0,
2%
(
both
@
10
hrs)
No
symptoms
noted.

1
Single
dose
of
carbofuran
applied
to
backs
of
volunteers.
Subjects
were
placed
in
an
enclosed
environment
with
normal
temperature/
normal
humidity
conditions
one
hour
before
dosing
and
then
for
four
hours
post­
dosing.
They
then
exercised
for
5
minutes,
rested
for
15
minutes
and
then
continued
this
cycle
11
times
(
four
hours).
2
Percent
decrease
provided
for
each
individual.
Maximum
inhibition
presented
for
all
individuals
and
the
time
point
associated
with
that
maximum.

Table
6:
Results
of
Dermal
Human
Study
(
Arnold,
1977)
with
Carbofuran:
Part
C
1
Dose
RBC
ChEI
2
Plasma
ChEI
2
Symptoms
1.0
mg/
kg
26%,
29%
(
both
@
24
hrs.
on
day
2)
43%,
49%
(
both
@
4
hrs
on
day
1)
No
symptoms
noted.

1
Single
dose
of
carbofuran
applied
to
backs
of
volunteers
for
three
successive
days.
Subjects
were
placed
in
an
enclosed
environment
with
high
temperature/
high
humidity
conditions
one
hour
before
dosing
and
then
for
four
hours
post­
dosing.
They
then
exercise
for
5
minutes,
rest
for
15
minutes
and
then
continued
this
cycle
11
times
(
four
hours).
2
Percent
decrease
provided
for
each
individual.
Maximum
inhibition
presented
for
all
individuals
and
the
time
point
associated
with
that
maximum.

Strengths/
Uncertainties/
Limitations:

The
following
strengths
of
the
Arnold,
1977
dermal
study
in
male
human
volunteers
have
been
identified:

 
Effects
were
observed
in
the
treated
subjects
in
Part
A
of
the
study
(
in
terms
of
both
subjective
and
objective
measures).
Page
10
of
19
 
Multiple
doses
were
used.
 
All
subjects
were
monitored
(
they
were
kept
at
the
center
from
the
night
before
dosing
up
to
24
hours
after
dosing).
 
The
ChEI
effects
observed
occurred
at
or
about
the
expected
peak
time
for
dermal
exposure
(
3­
4
hours
post­
dosing;
a
lag
associated
with
dermal
exposure
vs.
oral)
and
returned
to
almost
normal
within
six
hours
of
dosing.

The
following
uncertainties/
limitations
have
also
been
identified:

 
The
number
of
subjects
is
low
(
2
subjects)
and
placebos
were
only
used
in
one
of
the
three
experiments
(
Part
A).
 
All
tested
subjects
were
males.
 
There
was
no
statistical
analysis.
 
All
three
experiments
appear
to
have
been
"
open"
 
assumed
to
mean
that
both
the
investigator
and
subject
were
aware
that
the
subject(
s)
were
receiving
either
the
placebo
or
the
treatment
capsule.
 
There
was
potential
confounding
due
to
smoking
because
it
was
permitted,
but
unlike
the
oral
study
described
above,
no
details
were
provided
on
which
subject
smoked
or
how
much
they
may
have
smoked.
 
The
RBC/
plasma
ChEI
method
used
was
a
different
method
than
what
is
normally
used
(
as
mentioned
above
as
an
uncertainty
in
the
oral
study).
 
Duplicate
blood
samples
were
taken
to
analyze
for
carbofuran
and/
or
its
metabolites
but
the
data
have
not
been
submitted.
 
Individual
data
missing
from
the
study
report
included
clinical
signs,
pupil
size
and
eye
accommodation,
pulse
rate,
blood
pressure,
EKG,
respiration
rate,
body
temperature,
vestibular
function,
and
clinical
pathology.
 
No
rationale
or
justification
for
doses
selected
Conclusions
Although
effects
were
observed
in
Part
A
of
this
study,
it
is
important
to
note
that
the
subjects
were
under
atypical
conditions
(
high
temperature
and
high
humidity)
and
were
asked
to
perform
mild
exercise
(
stationary
bike)
for
five
minutes
eleven
times
over
a
four
hour
period
while
the
carbofuran
was
on
their
backs.
The
effects
observed
at
the
highest
dose
tested
(
2
mg/
kg)
resulted
in
both
marked
RBC
ChEI
and
cholinergic
symptoms
that
required
intervention
with
the
antidote
atropine
in
both
of
the
subjects
tested
at
this
dose.
Similar
symptoms
were
not
observed
under
normal
temperature/
humidity
conditions
 
at
much
higher
doses
(
up
to
32
mg/
kg)
but
following
the
same
exercise
regimen.
However,
it
is
believed
that
the
study
has
value
in
that
it
attempts
to
understand
dermal
absorption
and
possible
toxicity
to
carbofuran
under
high
heat/
humidity
 
conditions
that
may
exist
in
certain
occupational
settings
(
e.
g.,
outdoor
agricultural
working
conditions).
Thus,
OPP/
HED
believes
these
data
may
be
useful
in
a
hazard
assessment
as
a
PoD
(
with
a
LOAEL
of
0.5
mg/
kg
given
the
RBC
ChEI
observed
in
Part
A
 
see
Table
4).
Page
11
of
19
2b)
Arnold,
J.
D.
(
1978)
Comparison
of
Cholinesterase
Inhibition
and
Effects
of
Furadan
4F
and
FMC
35001
4
EC
(
ACT
152.03).
Rev.
final
rept.
(
Unpublished
study
received
Oct
24,
1979
under
279­
2712;
prepared
by
Quincy
Research
Center,
submitted
by
FMC
Corp.,
Philadelphia,
Pa.;
CDL:
241305­
A)
Accession
no.
241305,
MRID
no.
00092829.

Laboratory:
Quincy
Research
Center,
Kansas
City,
MO
Study
Dates:
Not
reported;
study
report
is
dated
1978.

Purpose
of
Study:
"
The
objective
of
this
study
was
to
compare
the
effects
of
single
cutaneous
applications
of
Furadan
4F
(
4F)
and
FMC
35001
4EC
(
EC)
in
men
exposed
to
high
temperature
and
humidity.
Specific
goals
were:
[
to
determine] .(
1)
effects
of
treatment
on
plasma
and
erthyrocyte
cholinesterase
activity,
(
2)
 .
the
minimal
dose
level
 
which
induces
symptoms
of
cholinesterase
inhibition,
(
3) .
the
effects
of
the
two
treatments
on
neurovegetative
signs ".

(
NOTE:
Furadan
4F
is
carbofuran
and
FMC
35001
4EC
is
carbosulfan,
a
carbofuran
analog
 
see
structure
below).

General
design:
In
an
open,
parallel
study
design,
volunteers
were
dermally
dosed
with
a
50%
test
article
dilution
[
undiluted
test
substance:
carbofuran
or
carbosulfan]
on
a
designated
portion
of
their
upper
backs
(
0.5
mg
per
square
centimeter)
approximately
1
½
hours
after
a
standard
breakfast.
Subjects
received
Furadan
4F
or
FMC
35001
4EC
in
groups
of
two;
no
subject
received
more
than
one
treatment
of
either
chemical.
From
0­
4
hours
post­
treatment,
subjects
mildly
exercised
for
5
minutes,
then
were
allowed
to
rest
for
15
minutes.
The
exercise/
rest
cycle
was
repeated
11
times
over
4
hours.
Subjects
were
kept
in
environmentally
controlled
rooms
of
high
temperature
and
high
humidity
(
91­
96
degrees
F
and
relative
humidity
70­
80%).
After
the
4
hour
dosing
interval,
the
dosages
were
removed
(
soap
and
water)
and
subjects
monitored
for
the
remainder
of
the
24
hour
post­
treatment
period.
Cigarette
smoking
was
not
allowed
1/
2
hour
before
treatment
and
until
2
¼
hours
after
dose
administration.

Subjects:
Twenty
males
(
eight
received
carbofuran
and
12
received
carbosulfan)
were
used
with
an
age
range
of
18­
53
years
old;
and
had
a
weight
range
of
1??
 
188
pounds
[
lower
value
unreadable
in
submitted
data].

Numbers/
Doses:
Groups
of
2
subjects
were
dosed
with
carbofuran
at
0.5,
1.0,
2.0,
or
4.0
mg/
kg.
Groups
of
2
subjects
were
dosed
with
carbosulfan
at
0.5,
1.0,
2.0,
4.0,
8.0,
or
16.0
mg/
kg.
Page
12
of
19
Table
7:
Acute
Dermal
Study
Design:
Arnold,
1978
1
Dose
(
mg/
kg)
Study
Phase
(
Session)
Control
0.5
1.0
2.0
4.0
8.0
16.0
Carbofuran
­
2
2
2
2
­
­

Carbosulfan
­
2
2
2
2
2
2
1
All
subjects
were
placed
in
a
room
under
high
temperature/
high
humidity
conditions
for
the
four
hour
exposure
period.

Measures:
RBC
and
Plasma
cholinesterase
activity
(
0 
hour/
pre­
dosing,
½
,
1,
2,
4,
6
,
and
24
hours);
EKG,
blood
pressure,
heart
rate,
temperature,
respiration,
pupil
size,
eye
accommodation,
hematology
and
urinalysis
were
measured
at
pre­
dosing
and
at
various
intervals
up
to
24
hours
after
dosing.
During
the
observation
period
(
24
hours)
subjects
were
monitored
for
clinical
signs.
As
noted
above
for
the
oral
study,
the
Voss
and
Sachsse
method
for
ChEI
determination
was
used.

Analysis:
There
was
no
statistical
analysis
of
the
data.

Study
Results
For
the
purposes
of
this
WOE,
only
the
carbofuran
data
are
presented
in
Table
8.
RBC
ChE
inhibition
values
were
based
on
self­
pretest
levels.
The
data
show
clear
cholinergic
effects
(
decrease
in
RBC
ChEI
and
associated
symptoms)
at
the
high
dose
of
4
mg/
kg.
As
with
the
dermal
study
described
above,
both
treated
subjects
at
this
dose
received
an
antidote
due
to
the
severity
of
the
response.
Although
the
4
mg/
kg
reported
here
represents
a
two­
fold
difference
in
carbofuran
amount
as
compared
to
the
2
mg/
kg
reported
for
the
other
dermal
study
(
Arnold,
1977),
the
differences
are
likely
due
to
the
fact
that
Arnold
(
1978)
uses
a
formulation
(
includes
a
higher
concentration
of
inert
ingredients)
with
4%
carbofuran
and
the
previously
reported
dermal
study
uses
a
product
that
contains
75%
carbofuran.
Page
13
of
19
Table
8:
Results
of
Carbofuran
Data
From
Comparative
Dermal
Study
1
Dose
RBC
ChEI
2
Plasma
ChEI
2
Symptoms
0.5
mg/
kg
22%,
7%
33%,
46%
(@
1
and
4
hrs)
One
subject
reported
nausea
[
at
40
min
and
2
hrs
10
min.
post­
dosing].
The
first
episode
lasted
10
min
and
the
second
about
40
min.
The
other
subject
reported
a
burning
sensation
at
application
site
that
lasted
about
5
min
[
at
1
hr,
50
min.
post­
dosing].

1.0
mg/
kg
29%,
21%
4%,
15%
(@
6
and
1
hrs)

2.0
mg/
kg
42%,
40%
44%,
6%
(@
2
and
24
hrs)
No
symptoms
reported
4.0
mg/
kg
61%,
49%
6%,
9%
(@
30
min
and
1
hr)
Both
subjects
reported
nausea,
dizziness
and
weakness.
One
also
reported
"
swollen
tongue",
increased
salivation,
and
stomach
cramps;
and
the
other
experienced
vomiting
and
tremors.
Most
symptoms
began
about
3
hrs.
post­
dosing
and
disappeared
within
2
hrs
of
onset.
In
both
cases
atropine
was
administered
as
an
antidote
[
in
the
first
case,
at
4
hours
and
in
the
second
at
3
hrs].
In
addition,
the
second
subject's
back
was
washed
to
remove
the
treatment
at
3
hrs
[
1
hour
early]
and
the
subject
was
removed
from
the
high
temp/
high
humid
room.
1
Single
dose
of
carbofuran
applied
to
backs
of
volunteers.
Volunteers
are
placed
in
an
enclosed
environment
under
high
temperature/
high
humidity
conditions.
They
then
exercise
for
5
minutes,
rest
for
15
minutes
and
then
continue
this
cycle
11
times
(
four
hours).
2
Percent
decrease
provided
for
each
individual.
Maximum
inhibition
presented
for
all
individuals.
For
RBC
values,
the
maximum
inhibition
was
seen
at
the
4­
hr
time
point
in
all
cases.

Strengths/
Uncertainties/
Limitations:

The
following
strengths
of
the
Arnold,
1978
dermal
study
in
male
human
volunteers
have
been
identified:

 
Effects
were
observed
in
the
treated
subjects
(
in
terms
of
both
subjective
and
objective
measures).
 
Multiple
doses
were
used.
 
All
subjects
were
monitored
(
they
were
kept
at
the
center
from
the
night
before
dosing
up
to
24
hours
after
dosing).
 
The
ChEI
effects
observed
occurred
at
or
about
the
expected
peak
time
(
4
hours
post­
dosing;
a
lag
associated
with
dermal
exposure
vs.
oral
and
in
agreement
with
the
values
measured
in
Arnold,
1977)
and
returned
to
almost
normal
within
six
hours
of
dosing.

The
following
uncertainties/
limitations
have
also
been
identified:

 
Only
two
volunteers
were
treated
at
each
dose
level.
Page
14
of
19
 
The
study
design
was
open
(
so
both
investigators
and
subjects
knew
that
all
volunteers
were
receiving
carbofuran).

 
There
were
no
control
subjects.

 
There
were
no
statistical
analyses.

 
Only
males
were
tested.

 
All
subjects
were
placed
in
a
high
temperature/
high
humidity
environment
and
were
required
to
exercise
 
The
carbofuran
product
used
was
a
formulation
(
i.
e.,
4%
carbofuran)
and
so
contains
other
ingredients
at
high
concentrations
that
confound
the
results
of
this
study
(
especially
when
compared
with
the
Arnold
(
1977)
study
described
earlier
which
used
a
75%
technical
produce).

Conclusions
The
comparative
dermal
toxicity
study
showed
apparent
cholinergic
effects
at
4
mg/
kg,
but
not
at
2
mg/
kg.
However,
comparison
of
RBC
ChE
inhibition
data
from
the
two
dermal
studies
show
similar
degrees
of
inhibition
at
the
same
doses
(
0.5,
1.0,
and
2.0
mg/
kg).
The
dermal
study
described
earlier
showed
effects
at
2
mg/
kg
(
the
highest
dose
tested
in
that
study).
The
study
designs
were
essentially
similar
between
the
two
studies,
with
the
major
difference
between
the
two
being
the
use
of
a
technical
product
(
75%
carbofuran
in
the
first
study)
and
the
use
of
a
formulation
(
4%
carbofuran)
in
this
study
may
explain
the
different
results
since
the
carbofuran
formulation
that
contains
numerous
inert
or
other
ingredients
that
could
inhibit
dermal
absorption.

Together,
the
two
dermal
studies
suggest
a
dermal
LOAEL
of
0.5
mg/
kg
based
on
RBC
ChEI
at
the
expected
peak
time
(
3­
4
hours)
with
the
appropriate
recovery
over
the
next
six
hours.
Thus,
this
dose
may
be
used
as
a
PoD
for
an
appropriate
occupational
dermal
exposure
scenario.

ANIMAL
Consistent
with
the
other
N­
methyl
carbamates,
the
effects
from
carbofuran
exposure
do
not
accumulate
over
time.
This
lack
of
accumulation
is
due
to
the
rapid
recovery
of
the
acetylcholinesterase.
Therefore,
the
most
appropriate
exposure
route
is
via
gavage
while
dietary
studies
are
less
appropriate.

There
are
several
studies
available
where
acute
ChE
inhibition
was
measured
at
or
near
peak
time
of
inhibition
(
15­
45
min)
and
which
inform
the
derivation
of
the
acute
RfD
in
the
rat.
These
include
two
studies
performed
by
the
registrant:
1)
time
course
study
(
MRID
no.
45675701)
where
male
and
female
rats
were
dosed
at
0.5
and
1.0
mg/
kg
and
2)
recently
submitted
comparative
ChE
study
where
adult
and
juvenile
(
post­
natal
day
11,
PND)
rats
were
dosed
at
0.3,
0.6,
and
1.0
mg/
kg
(
MRID
no.
46688914).
Clinical
signs
were
also
reported
for
adults
and
PND11
pups
in
the
comparative
ChE
study.
In
support
of
the
Agency's
cumulative
risk
assessment
for
the
N­
methyl
carbamates,
scientists
from
the
National
Health
and
Environmental
Effects
Research
Laboratory
(
NHEERL)
performed
dose­
response
studies
in
male
rat
where
brain
and
RBC
ChE
inhibition
along
with
motor
activity
were
measured.
For
carbofuran,
the
Agency's
study
included
doses
ranging
from
0.1
mg/
kg
up
to
1.5
mg/
kg
(
USEPA,
2005).

Table
9.
Benchmark
estimates
for
carbofuran
from
the
comparative
ChE
study
and
the
Preliminary
Cumulative
Risk
Assessment
for
the
N­
methyl
carbamate
pesticides.

Brain
RBC
Source
Male
Female
Male
Female
Page
15
of
19
BMD10
0.11
0.12
Adult
(
CCA)
BMDL10
0.05
0.06
Data
provides
no
dose­
response
relationship
BMD10
0.15
0.03
Preliminary
Cumulative
RA
BMDL10
0.13
N/
A
0.01
N/
A
BMD10
NA
NA
0.038
NA
Human­
Oral
BMDL10
NA
NA
0.025
NA
PROPOSED
USE
IN
SINGLE
CHEMICAL
ASSESSMENT
OPP
HED
proposes
that
the
single
oral
dose
human
study
(
BMDL10
of
0.026)
be
used
directly
as
a
point
of
departure.
Based
on
RBC
ChE
inhibition
at
the
lowest
dose
tested
(
0.5
mg/
kg)
in
both
dermal
studies,
and
using
a
LOAEL
to
NOAEL
extrapolation
factor
of
3X,
the
point
of
departure
is
0.17
mg/
kg
for
worker
exposure.

PROPOSED
USE
IN
N­
METHYL
CARBAMATE
CUMULATIVE
ASSESSMENT
1.
Background:

The
Food
Quality
Protection
Act
(
FQPA)
was
passed
by
Congress
in
1996.
The
FQPA
made
key
changes
to
the
approaches
used
by
EPA
to
assess
pesticide
chemicals.
One
of
these
changes
was
the
requirement
to
consider
cumulative
risk
to
those
pesticides
which
act
by
a
common
mechanism
of
toxicity.
Pesticides
are
determined
to
have
a
"
common
mechanism
of
toxicity"
if
they
act
the
same
way
in
the
body­­
that
is,
the
same
toxic
effect
occurs
in
the
same
organ
or
tissue
by
essentially
the
same
sequence
of
major
biochemical
events.
OPP
established
the
N­
methyl
carbamate
pesticides
(
NMCs)
as
a
common
mechanism
group
and
in
accordance
with
FQPA
has
developed
a
preliminary
cumulative
risk
assessment
for
this
group
of
pesticides
(
USEPA,
2005).
Carbofuran
is
a
member
of
the
NMC
common
mechanism
group.

OPP
has
developed
a
guidance
document
for
developing
cumulative
risk
assessments
under
FQPA
(
USEPA,
2002).
This
guidance
indicates
that
when
developing
a
multi­
chemical
hazard
assessment,
comparison
of
toxic
potency
should
be
made
using
a
uniform
basis
of
comparison,
by
using
to
the
extent
possible
a
common
response
derived
from
a
comparable
measurement
methodology,
species,
and
sex
for
all
the
exposure
routes
of
interest.
In
the
preliminary
cumulative
risk
assessment,
the
Agency
considered
RBC
and
brain
ChE
inhibition
as
potential
endpoints.
Plasma
cholinesterase
data
were
not
considered
since
the
primary
enzyme
in
plasma
is
butylcholinesterase
and
not
acetylcholinesterase.
Ultimately,
brain
ChE
data
from
acute
rat
toxicity
studies
measured
at
or
near
the
time
of
peak
effect
have
been
used
by
EPA
to
estimate
a
relative
potency
factor
(
RPF)
and
to
develop
the
points
of
departure
(
PoD)
for
extrapolating
cumulative
risk.
For
instance,
the
brain
BMD10
has
been
used
to
calculate
the
RPF
while
the
brain
BMDL10
establishes
the
PoD
in
the
preliminary
cumulative
risk
assessment.
Brain
data
have
been
selected
over
RBC
data
as
brain
ChE
inhibition
represents
a
direct
measure
of
the
target
tissue
(
as
opposed
to
blood
data
which
is
considered
a
surrogate
measure)
and
brain
ChE
inhibition
data
tend
to
have
less
variation
and
thus
confer
less
uncertainty
on
cumulative
risk
estimates.
Page
16
of
19
Because
data
from
rat
studies
provide
the
basis
for
potency
determination,
the
Agency
must
consider
interspecies
extrapolation
(
i.
e.,
animal
to
human)
in
its
cumulative
risk
assessment.
As
such,
human
data
may
be
used
by
the
Agency
to
inform
the
pesticide­
specific
interspecies
extrapolation.
In
the
specific
case
of
carbofuran,
MRID
00092826
is
available.

2.
Carbofuran
Human
Study
Summary:

The
single
oral
human
toxicity
study
for
carbofuran
does
not
provide
brain
ChE
data,
for
obvious
reasons,
but
does
provide
RBC
ChE
data
for
male
volunteers.
The
blood
ChE
activity
(
RBC)
provided
in
the
human
study
is
considered
appropriate
surrogate
measures
of
potential
effects
on
peripheral
nervous
system
(
PNS)
acetylcholinesterase
(
AChE)
activity,
and
of
potential
effects
on
the
central
nervous
system
(
CNS)
when
brain
ChE
data
are
lacking
(
USEPA
2000).
AChE
is
the
target
enzyme
for
the
cumulative
risk
assessment
and
is
the
primary
form
of
ChE
found
in
RBCs.
Butylcholinesterase
(
BChE),
on
the
other
hand,
is
the
primary
for
of
ChE
found
in
plasma.
BChE
is
considered
a
measure
of
exposure
but
has
not
been
shown
to
be
of
toxicological
significance.
As
with
the
RBC
ChE
data
from
the
aldicarb,
methomyl,
and
oxamyl
human
studies
that
were
presented
to
the
HSRB
in
April
2006,
the
RBC
ChE
data
from
the
single
oral
carbofuran
human
study
also
is
being
utilized
by
the
Agency
to
inform
the
pesticide­
specific
interspecies
extrapolation.

The
measured
RBC
ChE
activity
from
the
oral
human
study
is
adequate
for
estimation
of
BMD
and
BMDL
estimates.
The
RBC
ChE
data
from
the
carbofuran
human
study
was
utilized
in
the
model
in
the
same
manner
as
the
RBC
data
from
the
oral
human
studies
for
aldicarb,
methomyl,
and
oxamyl.
The
BMD10
and
BMDL10
estimates
for
both
rat
(
RBC,
brain)
and
human
(
RBC)
are
included
in
Table
9
.
It
should
be
noted
that
the
BMD
estimates
for
the
rat
include
both
sexes
while
the
BMD
estimates
from
the
human
study
only
include
male
subjects.

Based
on
the
FIFRA
SAP
(
2005)
approval
of
statistical
analyses
for
the
BMD
model,
the
single
RBC
BMD
estimate
for
carbofuran
indicates
similar
ChE
activity
in
males
and
females
(
0.031
mg/
kg,
M
and
F).
Comparison
of
the
rat
BMD
estimates
from
the
two
compartments
indicates
the
RBC
compartment
is
slightly
more
sensitive
than
the
brain.
The
RBC
ChE
data
from
the
human
study,
therefore,
would
also
be
expected
to
be
protective
of
brain
ChE
inhibition.
As
such,
the
BMD
estimate
from
the
carbofuran
human
study
provides
useful
information
into
the
sensitivity
of
RBC
ChE
inhibition
of
rats
compared
to
humans.

3.
Discussion
Several
studies
for
carbofuran
are
available
that
provide
quality
dose­
response
and
ChE
inhibition
data
from
both
the
rat
and
human.
As
presented
for
aldicarb,
methomyl,
and
oxamyl
at
the
April
2006
HSRB,
the
cumulative
risk
assessment
for
carbofuran
also
must
extrapolate
information
across
compartments
(
blood­
brain).
The
preliminary
NMC
cumulative
risk
assessment
relies
on
rat
brain
ChE
data
for
the
relative
potency
factors
(
RPFs)
and
points
of
departure
(
PoDs).
The
FIFRA
SAP
supported
the
Agency's
use
of
brain
ChE
data
in
August
2005
(
FIFRA
SAP
2005).

Similar
to
the
approach
proposed
by
the
Agency
at
the
April,
2006
for
aldicarb,
methomyl,
and
oxamyl
for
informing
the
interspecies
extrapolation
factor
in
the
cumulative
risk
assessment,
the
carbofuran
human
study
may
also
inform
the
interspecies
extrapolation
factor
for
the
preliminary
cumulative
risk
assessment.
The
ratio
of
the
rat
BMD10
to
the
human
BMD10
was
proposed
at
the
April
2006
HSRB.
The
Agency
is
proposing
to
use
the
same
approach
for
carbofuran.
The
Agency
is
in
the
process
of
analyzing
both
the
rat
and
human
BMD10
data
to
determine
the
central
estimate
and
95%
confidence
interval
for
use
as
the
interspecies
extrapolation
factor.
A
rough
estimate
of
the
interspecies
extrapolation
factor
for
carbofuran
may
be
made
by
comparing
the
RBC
BMD10
values
for
the
rat
and
human
from
Table
X
above.
This
ratio
is
approximately
1X.
The
interspecies
extrapolation
factor
resulting
from
the
formal
BMD
ratio
analysis
would
be
in
addition
to
the
other
uncertainty
factors
for
the
cumulative
risk
assessment
that
includes
intraspecies
variability
(
human
variability)
and
FQPA.
Page
17
of
19
References
Voss,
G
and
K
Sachsse.
1970.
Red
cell
and
plasma
cholinesterase
activities
in
microsamples
of
human
and
animal
blood
determined
simultaneously
by
a
modified
acetylthiocholine/
DTNB
procedure
Toxicology
and
Applied
Pharmacology,
16:
764­
777.

Burnam,
W.
1997.
"
Discussion
of
Outside
Peer
Review
Comments
on
the
Carbofuran
RfD".
Memorandum
to
Tina
Levine
entitled
"

FIFRA
SAP
(
2005).
Meeting
Minutes
of
the
FIFRA
Scientific
Advisory
Panel
Held
August
23­
26,
2005.
SAP
Minutes
No.
2005­
04.
Preliminary
N­
Methyl
Carbamate
Cumulative
Risk
Assessment.
October
13,
2005.

USEPA
(
2000).
"
The
Use
of
Data
on
Cholinesterase
Inhibition
for
Risk
Assessments
of
Organophosphorous
and
Carbamate
Pesticides";
August
18,
2000.
Available:
http://
www.
epa.
gov/
pesticides/
trac/
science/
cholin.
pdf
USEPA
(
2002).
"
Guidance
on
Cumulative
Risk
Assessment
of
Pesticide
Chemicals
That
Have
a
Common
Mechanism
of
Toxicity."
January
14,
2002.
(
67
FR
2210;
January
16,
2002)
http://
www.
epa.
gov/
oppfead1/
trac/
science/#
common
USEPA
(
2005).
Preliminary
N­
Methyl
Carbamate
Cumulative
Risk
Assessment.
Office
of
Pesticide
Programs,
U.
S.
Environmental
Protection
Agency.
Washington,
DC.
http://
www.
epa.
gov/
scipoly/
sap/
index.
htm#
sept
Page
18
of
19
APPENDIX
1
Red
cell
and
plasma
cholinesterase
activities
in
microsamples
of
human
and
animal
blood
determined
simultaneously
by
a
modified
acetylthiocholine/
DTNB
procedure
Guenther
Voss
and
Klaus
Sachsse
Agrochemical
Division
of
CIBA
Ltd,
Basle,
Switzerland
Received
3
March
1969.
Available
online
27
September
2004.

Abstract
A
modification
of
the
acetylthiocholine/
DTNB
method
has
been
developed
for
the
simultaneous
determination
of
red
cell
and
plasma
cholinesterases
in
samples
of
only
0.01 
0.03
ml
of
whole
human
and
animal
blood,
using
a
relatively
short
incubation
period
of
10
min
and
an
incubation
temperature
of
30
°
C.
In
contrast
to
many
other
micromethods,
these
test
conditions
allow
activity
determinations
of
cholinesterases
inhibited
by
insecticidal
carbamates
in
vivo,
because
decarbamylation
of
the
enzymes
after
dilution
is
comparatively
low
after
10
min
at
30
°
C.
Human
blood
cholinesterases
are
assayed
with
propionylthiocholine,
whereas
for
blood
samples
of
various
laboratory
animals
acetylthiocholine
was
found
to
be
the
better
substrate.
The
experimental
procedure
of
this
micromethod
is
based
on
two
cholinesterase
measurements,
of
which
the
first
determines
total
activity
in
whole
blood,
and
the
second,
plasma
cholinesterase
activity
alone.
Erythrocyte
cholinesterase
activity
is
determined
by
subtraction.
Normal
activity
values
of
the
enzymes
in
red
cells,
plasma,
and
brain
are
given
for
a
variety
of
species,
and
a
few
in
vivo
inhibition
data
after
organophosphate
and
carbamate
poisoning
are
also
presented.
Page
19
of
19
APPENDIX
2
Appendix
2:
RBC
ChEI
Data
(
Percent
Change
from
Baseline)
in
Human
Single
Oral
Dose
Study
1
1
2
3
4
5
6
7
8
9
Time
of
Blood
Sample
0.05
mg/
kg
0.1
mg/
kg
0.25
mg/
kg
Placebo
Pre
­
­
­
­
­
­
­
­
­
30
min
­
8
+
5
­
29
­
15
­
21
­
5
+
12
­??
2
+
6
1
hr
­
22
­
11
­
33
­
31
­
58
­
63
­
46
­
59
­
10
2
hr
­
­
­
­
­
46
­
49
???
2
­
52
+
3
3
hr
+
5
+
3
­
4
­
2
­
62
­
57
­
12
­
26
­
1
6
hr
+
8
+
7
0
+
12
­
8
0
+
6
+
5
+
28
24
hr
+
12
+
5
+
1
+
5
+
24
+
27
+
51
+
44
+
40
1
Subject
number.
Subjects
1
and
2
received
0.05
mg/
kg,
subjects
3
and
4
received
0.1
mg/
kg,
subjects
5
through
8
received
0.25
mg/
kg
and
subject
9
was
the
lone
placebo
in
the
study.
2
Value
unreadable
on
data
table
in
submitted
report.

Appendix
2:
Number
of
Cigarettes
Consumed
During
the
Human
Single
Oral
Dose
Study
1
1
2
3
4
5
6
7
8
9
Time
Post­
Dosing
0.05
mg/
kg
0.1
mg/
kg
0.25
mg/
kg
Placebo
0­
1
hr
0
0
0
0
0
0
0
0
0
1­
2
hr
3
2
2
0
0
0
0
1
1
2­
3
hr
2
2
0
2
0
0
1
1
1
3­
4
hr
1
0
1
2
0
0
0
0
1
4­
5
hr
1
2
1
1
0
0
0
1
2.5
5­
6
hr
1
2
0
0
0
0
0
0
2
6­
7
hr
0
2
2
0
0
0
1
1
1
7­
8
hr
1
1
1
2
0
0
1
2
3
TOTAL
9
11
7
7
0
0
3
6
11.5
1
Subject
number.
Subjects
1
and
2
received
0.05
mg/
kg,
subjects
3
and
4
received
0.1
mg/
kg,
subjects
5
through
8
received
0.25
mg/
kg
and
subject
9
was
the
lone
placebo
in
the
study.
