DATA
EVALUATION
RECORD
METHOMYL/
90301
NON­
GUIDELINE
STUDY
STUDY
TYPE:
ASCENDING
ACUTE
ORAL
TOXICITY
STUDY
IN
HUMANS
MRID
44721401
Prepared
for
Health
Effects
Division
Office
of
Pesticide
Programs
U.
S.
Environmental
Protection
Agency
1801
Bell
Street
Arlington,
VA
22202
Prepared
by
Toxicology
and
Hazard
Assessment
Group
Life
Sciences
Division
Oak
Ridge
National
Laboratory
Oak
Ridge,
TN
37831
Task
Order
No.
74­
2005
Primary
Reviewer:
Judith
H.
Moyer,
Ph.
D.,
D.
A.
B.
T.
Signature:
Date:
Secondary
Reviewers:
Signature:
Sylvia
Milanez,
Ph.
D.,
D.
A.
B.
T.
Date:

Robert
H.
Ross,
M.
S.,
Group
Leader
Signature:
Date:
Quality
Assurance:
Lee
Ann
Wilson,
M.
A.
Signature:
Date:

Disclaimer
This
review
may
have
been
altered
subsequent
to
the
contractors
=

signatures
above.

Oak
Ridge
National
Laboratory
managed
and
operated
by
UT­
Battelle,
LLC.,
for
the
U.
S.
Department
of
Energy
under
Contract
No.
DE­
AC05­
00OR22725.
METHOMYL/
90301
Ascending
Acute
Oral
Toxicity
Study
(
1998)
Page
2
of
12
Non­
guideline
EPA
Reviewer:
Elissa
Reaves,
Ph.
D.
Signature:
Reregistration
Branch
2,
Health
Effects
Division
(
7509C)
Date
EPA
Secondary
Reviewer:
Anna
Lowit,
Ph.
D.
Signature:
Reregistration
Branch
2,
Health
Effects
Division
(
7509C)
Date
Template
version
11/
01
TXR#:
0052872
DATA
EVALUATION
RECORD
STUDY
TYPE:
Ascending
Acute
Oral
Toxicity
­
Humans,
non­
guideline.

PC
CODE:
90301
DP
BARCODE:
308718
TEST
MATERIAL
(
PURITY):
Ethanimidothioic
acid,
N­[{(
methylamino)
carbonyl}
oxy]­,
methyl
ester
(
Methomyl)
(
89%)

SYNONYMS:
Lannate
7
SP,
S­
methyl
N­[(
methylcarbamoyl)
oxy]
thioacetimidate,
Lannate
90,
DPX­
X1179.

CITATION:
McFarlane,
P.,
Sanderson,
J.
B.,
Freestone,
S.
(
1998)
A
randomized
double
blind
ascending
oral
dose
study
with
methomyl
to
establish
a
no
adverse
effect
level.
Inveresk
Clinical
Research,
Riccarton,
Edinburgh,
EH14
4AP,
Scotland.
Laboratory
Project
ID:
HLO­
1998­
00969,
November
30,
1998.
MRID
44721401.
Unpublished.

SPONSOR:
E.
I.
du
Pont
de
Nemours
and
Company,
Newark,
Delaware
19714­
0050
EXECUTIVE
SUMMARY:
In
a
non­
guideline,
ascending
acute
oral
toxicity
study
(
MRID
44721401),
19
healthy
human
male
volunteers,
ages
18
­
40
years,
were
each
given
a
single
oral
dose
of
a
methomyl
formulation
(
Lannate
7
SP,
approximately
89%
a.
i.,
batch
#:
T
101397­
00)
in
a
capsule
at
doses
of
0,
0.1,
0.2,
or
0.3
a.
i.
mg/
kg
bw
following
a
A
standard
@

breakfast,
and
observed
for
two
nights
and
one
follow­
up
visit
7
("
2)
days
post­
dose.
Volunteers
were
admitted
to
the
clinic
the
afternoon
prior
to
the
morning
dosing
and
were
requested
to
fast
for
9
hours
prior
to
breakfast.
The
study
was
conducted
as
a
double­
blinded
ascending­
dose
escalation
clinical
trial,
and
each
male
was
treated
at
one
of
four
dosing
sessions.
All
volunteers
remained
under
close
medical
and
nursing
supervision
throughout
the
study.
Parameters
evaluated
were
physical
examination
and
urinalysis
at
screening
and
24
hours
post­
dosing;
vital
signs
(
i.
e.,
blood
pressure
and
heart
rate),
salivary
quantity
by
weight
(
secreted
within
5
minutes),
and
pupillometry
at
screening,
16
hours
pre­
dosing,
30
minutes
pre­
dosing,
and
1,
2,
3,
4,
8,
and
24
hours
postdosing
oral
temperature
at
screening,
16
hours
pre­
dosing,
30
minutes
pre­
dosing,
2,
4,
and
24
hours
post­
dosing;
12­
lead
electrocardiogram
(
ECG)
recorded
at
screening,
30
minutes
predosing
30
minutes
post­
dosing,
and
2,
3,
and
24
hours
post­
dosing;
continuous
ECG
monitoring
from
30
minutes
pre­
dosing
through
3
hours
post­
dosing;
hematology
and
clinical
chemistry
at
screening,
30
minutes
pre­
dosing,
and
24
hours
post­
dosing;
and
plasma
and
red
blood
cell
(
RBC)
cholinesterase
activities
at
screening,
16
hours
pre­
dosing,
30
minutes
pre­
dosing,
every
15
METHOMYL/
90301
Ascending
Acute
Oral
Toxicity
Study
(
1998)
Page
3
of
12
Non­
guideline
minutes
for
the
first
2
hours
post­
dosing,
and
then
hourly
through
8
hours,
at
24
hours,
and
one
week
later.
Four
volunteers
(
one
volunteer
at
each
concentration)
throughout
the
4
Sessions
demonstrated
a
greater
than
40%
inhibition
of
RBC
cholinesterase
activity
from
that
individuals
baseline
(
Session
1:
0.1
mg/
kg,
­
43.5%
at
8hrs
post­
dose;
Session
2:
0.2
mg/
kg,
­
40.6%
at
45
minutes
post­
dosing
and
headache
at
105
minutes
post­
dosing;
Session
3:
0.3
mg/
kg,
­
43%
at
45
minutes
post­
dosing;
Session
4:
0.2
mg/
kg,
­
41%
at
75
minutes
post­
dosing).
RBC
cholinesterase
activity
returned
to
baseline
by
6
hours
post­
dosing
in
all
volunteers
with
the
exception
of
one
volunteer
receiving
0.1
mg/
kg
(
8
hrs
post­
dosing).

A
dose­
response
relationship
was
observed
in
all
dose
groups
for
plasma
and
RBC
cholinesterase
activity.
In
addition,
cholinesterase
activity
for
both
plasma
and
RBC
was
consistent
for
timing
of
peak
effect
and
time
to
recovery.
In
the
high
dose
group,
the
mean
percent
change
in
RBC
cholinesterase
activity
was
statistically
significantly
decreased
compared
to
placebo
activity
from
the
first
time
point
at
15
minutes
(­
18.6%)
to
4
hours
post­
dosing
(­
5.0%),
with
peak
inhibition
at
45
minutes
(­
35.2%)
and
recovery
at
6
hours
post­
dosing.
At
the
mid­
dose,
mean
percent
change
in
RBC
cholinesterase
activity
was
statistically
significantly
decreased
compared
to
placebo
activity
beginning
at
45
minutes
post­
dosing
(­
20.0%)
until
2
hours
post­
dosing
(­
16.2%),
with
peak
inhibition
at
1
hour
and
30
minutes
(­
27.9%)
and
recovery
at
3
hours
post­
dosing.
The
mean
percent
change
in
RBC
cholinesterase
activity
for
the
low
dose
(
0.1
mg/
kg)
was
statistically
similar
to
placebo
activity
at
all
time
points.
However,
at
60,
75,
and
90
minutes
post­
dosing,
the
percent
change
in
mean
RBC
cholinesterase
activity
was
­
14.6%
,
­
19.0%,
and
­
10.5%
of
the
mean
group
baseline
level,
respectively.
The
timing
of
the
mean
RBC
cholinesterase
activity
coincides
with
the
inhibition
of
RBC
cholinesterase
activity
in
the
mid­
and
high­
dose
groups.

The
mean
percent
change
in
plasma
cholinesterase
activity
was
statistically
significantly
decreased
compared
to
placebo
activity
in
the
high
dose
(
0.3
mg/
kg)
beginning
at
15
minutes
post­
dosing
(­
9.8%)
until
4
hours
post­
dosing
(­
8.1%),
with
peak
inhibition
at
45
minutes
(­
21.1%)
and
recovery
at
6
hours
post­
dosing.
In
the
mid­
dose
group
(
0.2
mg/
kg)
the
mean
percent
change
from
baseline
plasma
cholinesterase
activity
compared
to
placebo
was
statistically
significantly
decreased
beginning
at
45
minutes
post­
dosing
(­
11.5%)
until
2
hours
post­
dosing
(­
10.3%)
with
peak
inhibition
at
1
hour
45
minutes
(­
13.5%)
and
recovery
at
3
hours
post­
dosing.
Mean
percent
change
in
plasma
cholinesterase
activity
for
the
low
dose
(
0.1
mg/
kg)
was
statistically
similar
to
placebo
activity
at
all
time
points.
Plasma
cholinesterase
activity
was
only
statistically
significantly
decreased
at
2
hours
post­
dosing
(­
7.2%)
when
outliers
were
excluded.

Increases
in
saliva
weight
were
dose­
related
at
the
one­
hour
timepoint,
with
the
0.3
mg/
kg
volunteers
at
60.3%
of
baseline
weight,
suggesting
a
potentially
cholinergic
response
to
the
treatment.

Three
volunteers
had
increased
total
bilirubin
at
least
once
during
the
study.
The
first
volunteer
(
0.1
mg/
kg)
had
increased
total
bilirubin
at
30
minutes
pre­
dosing
only.
The
second
(
0.2
mg/
kg)
and
third
(
0.3
mg/
kg)
volunteer
had
increased
total
bilirubin
at
screening,
30
minutes
pre­
dosing,
and
24
hours
post­
dosing.
METHOMYL/
90301
Ascending
Acute
Oral
Toxicity
Study
(
1998)
Page
4
of
12
Non­
guideline
No
dose
group
had
changes
in
pupillary
size,
respiratory
rate,
ECGs,
vital
signs,
hematology,
clinical
chemistry,
urinalysis,
or
clinical
signs
of
cholinergic
effects
(
with
the
exception
of
the
0.3
mg/
kg
individual
who
complained
of
a
transient
headache,
and
the
early
increase
in
salivation).

Under
the
conditions
of
this
ascending
oral
study,
the
NOAEL
for
methomyl
in
humans
is
<
0.1
mg/
kg.
The
LOAEL
is
0.1
mg/
kg,
based
on
decreased
peak
RBC
cholinesterase
activity
(­
19%).

The
Agency
generated
BMD
and
BMDL
estimates
based
on
the
RBC
ChE
data
from
this
study.
The
resulting
BMD10
is
0.035
mg/
kg
with
BMDL10
of
0.015
mg/
kg.

COMPLIANCE:
Signed
and
dated
Good
Clinical
Practice
Compliance,
Quality
Assurance,
and
No
Data
Confidentiality
statements
were
provided.
The
study
was
conducted
in
accordance
with
the
Declaration
of
Helsinki,
1964,
as
amended
by
the
29th
Medical
World
Assembly
in
Venice,
1983,
41st
Medical
World
Assembly
in
Hong
Kong,
1989,
and
the
48th
General
Assembly,
Somerset
West,
Republic
of
South
Africa,
October
1996.

I.
MATERIALS
AND
METHODS
A.
MATERIALS:

1.
Test
material:
Lannate7
SP
Description:
White
solid;
Aappeared
to
be
stable@
under
study
conditions
Lot/
Batch
#:
Batch
No.
T101397­
00
Purity:
Approx.
89%
a.
i.,
approx.
11%
inerts
CAS
#
of
TGAI:
16752­
77­
5
2.
Vehicle
and/
or
positive
control:
Methomyl
formulation
was
administered
in
a
gelatin
capsule.
Placebo
was
hydrated
silica
(
Batch
No.
H­
10­
7)
administered
in
a
matching
capsule.

3.
Volunteers:
Species:
Human
(
Male)
Strain:
N.
A.
Age/
weight
at
dosing:
Age:
18
­
40
years;
Weight:
60.6
­
91.9
kg
Source:
Volunteers
recruited
and
screened
for
inclusion
in
the
study
by
ICR
clinical
staff.
Housing:
Admitted
to
clinic
the
afternoon
prior
to
morning
dosing,
and
discharged
approx.
24
hours
postdose
Diet:
AStandard@
breakfast
approx.
5
minutes
before
dosing;
fasted
until
approx.
3
hours
post­
dose
and
then
allowed
decaffeinated
fluids;
and
a
light
lunch
approx.
4
hours
post
dosing.
Water:
Water
consumption
not
specified.
Environmental
conditions:
Temperature:
Humidity:
Air
changes:
Photoperiod:
Not
specified
Not
specified
Not
specified
Not
specified
Acclimation
period:
Volunteers
admitted
to
clinic
the
afternoon
before
dosing
the
next
a.
m.
METHOMYL/
90301
Ascending
Acute
Oral
Toxicity
Study
(
1998)
Page
5
of
12
Non­
guideline
B.
STUDY
DESIGN
and
METHODS:

1.
Study
dates:
Start:
November
12,
1997
End:
November
30,
1998
2.
Volunteer
population:
Volunteers
(
19
total)
were
assigned
to
the
test
groups
noted
in
Table
1,
and
were
admitted
to
the
clinic
the
afternoon
before
the
study.
With
the
exception
of
one
Asian,
all
volunteers
were
white
males.
All
were
healthy;
14
were
non­
smokers,
and
5
were
previous
smokers.
Two
volunteers
were
non­
drinkers,
and
the
remaining
reported
they
regularly
consumed
moderate
amounts
of
alcohol.

3.
Blinding:
The
study
design
was
double
blind
and
placebo
controlled.
Dose
escalation
was
not
to
occur
if
there
were
clinically
significant
symptoms/
signs
of
carbamate
toxicity
or
if
any
volunteer
had
$
40%
inhibition
of
RBC
cholinesterase
without
associated
symptoms/
signs
of
carbamate
toxicity.
If
there
were
associated
symptoms/
signs
of
carbamate
toxicity,
no
further
administration
of
that
particular
dose
would
occur.
The
allocation
to
active
or
placebo
was
randomized
and
a
copy
of
the
randomization
code
was
held
by
the
ICR
pharmacist
where
it
was
required
for
dispensing
purposes
and
by
the
Regulatory
Affairs
Department
at
Inveresk
Research.
Sealed
disclosure
envelopes
were
also
provided
to
ICR.
In
the
event
of
an
emergency
requiring
identification
of
the
drug
administered
to
a
volunteer,
the
study
director
could
request
that
the
envelope
by
opened.
The
blindeness
of
the
study
was
broken
on
completion
of
group
three
in
order
to
assess
the
link
between
the
cholinesterase
inhibition
and
active
test
compound.
A
new
randomized
code
was
generated
for
a
modified
Session
4
dosed
with
0.2
mg/
kg
bw
or
placebo.

4.
Experimental
Design:
Approximately
5
minutes
after
the
completion
of
a
Astandard@
breakfast,
the
volunteers
were
given
a
single
dose
of
the
formulated
product
Lannate7SP
(
Batch
No.
T101397­
00)
at
dosing
levels
of
0,
0.1,
0.2,
or
0.3
a.
i.
mg/
kg
bw
while
sitting,
with
150
mL
water.
The
formulation
contained
approximately
89%
Methomyl
as
the
a.
i.,
and
11%
inerts.
Control
volunteers
were
given
a
placebo
(
hydrated
silica
­
Batch
No.
H­
10­
7)
by
capsule.
The
doses
were
adjusted
for
a
test
substance
with
approximately
89%
purity.

During
the
first
of
4
sessions,
one
volunteer
received
a
placebo
and
the
other
received
the
0.1
mg/
kg
body
weight
dose.
The
second
session
consisted
of
one
volunteer
receiving
a
placebo,
4
receiving
the
0.1
mg/
kg
dose,
and
one
volunteer
receiving
the
0.3
mg/
kg
dose.
Session
3
consisted
1
volunteer
receiving
the
placebo
and
4
receiving
0.3
mg/
kg
dose
with
the
1
volunteer
at
0.5
mg/
kg
being
dropped.
A
greater
than
40%
RBC
cholinesterase
inhibition
occurred
in
Session
3
and
therefore,
upon
unblinding
the
study,
Session
4
was
modified
to
include
1
volunteer
receiving
placebo
and
4
receiving
0.3
mg/
kg
instead
of
0.5
mg/
kg
methomyl.
The
study
was
then
reblinded
and
the
4th
session
consisted
of
1
volunteer
receiving
the
placebo
and
5
receiving
the
0.2
mg/
kg
dose.
All
volunteers
were
observed
Aunder
close
medical
and
nursing
supervision@
for
approximately
24
hours
after
substance
administration.
Volunteers
were
weighed
on
an
unspecified
date.
Volunteers
were
released,
with
their
agreement
to
return
within
7
("
2)
days
for
follow­
up
observation
of
continued
well­
being,
evaluation
of
any
outstanding
adverse
events,
and
for
measurement
of
plasma
and
red
blood
cell
(
RBC)
cholinesterase
activity.
METHOMYL/
90301
Ascending
Acute
Oral
Toxicity
Study
(
1998)
Page
6
of
12
Non­
guideline
TABLE
1.
Study
design
Doses
of
methomyl
administered
(
mg/
kg
bw)
and
number
of
volunteers
Session
Numbers
0
(
Placebo)
0.1
0.2
0.3
0.5
1
1
1
2
1
4
1
3
1
4
1
(
dropped)*

4
1
5
Total
Volunteers
=
19
4
5
5
5
0
Data
obtained
from
p.
34,
MRID
44721401.
*
No
dosing
at
0.5
mg/
kg
occurred
in
Session
3
as
>
40%
RBC
inhibition
was
obtained.

5.
Clinical
evaluation:
Systolic
and
diastolic
blood
pressure
and
heart
rate
were
measured
at
admission
(
16
hours
pre­
dose)
and
30
minutes
pre­
dose,
and
at
1,
2,
3,
4,
8,
and
24
hours
post­
dose.
A
12­
lead
electrocardiogram
(
ECG)
was
obtained
at
screening
(
within
14
days
prior
to
study
commencement),
30
minutes
pre­
dose,
30
minutes
post­
dose,
and
1,
2,
and
24
hours
post­
dose.
Blood
was
collected
at
screening,
30
minutes
pre­
dose,
and
at
0.25,
0.5,
0.75,
1.0,
1.25,
1.5,
1.75,
2,
3,
4,
6,
8,
12,
and
at
24
hours
and
7
("
2)
days
post­
dose.
Plasma
and
red
cell
fractions
were
immediately
separated
and
chilled
in
liquid
nitrogen,
and
assayed
for
cholinesterase
activity
using
the
method
of
Ellman,
1961
(
as
adapted
as
a
clinical
chemistry
kit
and
anzalyzed
on
a
Hitachi
Clinical
Chemistry
Analyzer).
Urinalysis
was
evaluated
at
screening
and
24
hours
post­
dose.

Pupillometry
was
conducted
at
16
hours
pre­
dose,
30
minutes
pre­
dose,
and
1,
2,
3,
4,
8,
and
24
hours
post­
dose,
using
the
optical
unit
(
pupilscan,
hand­
held
electronic
pupillometer).
Saliva
was
collected
and
quantified
by
weight
at
16
hours
pre­
dose,
30
minutes
pre­
dose,
and
1,
2,
3,
4,
8,
and
24
hours
post­
dose
by
having
the
volunteers
place
2
sterilin­
treated,
weighed
dental
rolls
opposite
the
2nd
molar
both
on
the
upper
cheek
pouch
on
both
sides
for
5
minutes.
The
dental
rolls
were
then
replaced
in
the
sterilin
and
the
pre­
and
post­
collection
weights
were
used
to
determine
the
salivary
weight.
Single­
channel,
continuous
ECG
monitoring
was
performed
from
30
minutes
pre­
dose
to
3
hours
post­
dose.

6.
Statistics:
The
SAS
(
v6.07)
statistical
package
was
used
to
perform
statistical
analyses.
The
mean,
standard
deviation,
minimum,
maximum,
and
number
of
volunteers
for
pupillometry
(
initial,
minimum,
recovery,
and
change
from
initial
to
minimum),
vital
signs,
saliva
collection,
and
plasma
and
RBC
cholinesterase
activity
was
analyzed
and
summarized
by
dose
level
and
timepoint.
When
both
16
hour
pre­
dose
and
30
minute
pre­
dose
values
were
taken,
baseline
(
for
each
individual)
was
defined
as
the
mean
of
these
2
values.

A
repeated
measures
analysis
of
variance
(
ANOVA)
­
including
terms
for
dose
level,
timepoint,
and
dose
level
by
timepoint
interaction
­
were
used
to
analyze
the
percentage
change
from
baseline
for
RBC
and
plasma
cholinesterase
activity,
pupillometry,
and
saliva
collection.
At
each
timepoint,
a
test
for
linear
trend
with
dose
was
performed
using
a
linear
METHOMYL/
90301
Ascending
Acute
Oral
Toxicity
Study
(
1998)
Page
7
of
12
Non­
guideline
contrast.
Using
the
error
variance
from
the
ANOVA,
pairwise
comparisons
between
placebo
and
each
dose
level
were
carried
out
at
each
timepoint
using
the
Student=
s
>
t=­
test.
If
the
test
for
linear
trend
was
significant
at
the
5%
level,
then
the
pairwise
comparisons
at
that
timepoint
were
not
adjusted
for
multiple
comparisons.
If
the
test
for
linear
trend
was
not
significant
at
the
5%
level,
a
Bonferroni
adjustment
was
applied
to
the
pairwise
comparisons
at
that
timepoint
(
i.
e.,
each
comparison
was
tested
at
the
1.7%
significance
level).
Treatment
group
LSMeans
(
i.
e.,
means
adjusted
for
any
imbalance
in
the
model)
were
presented
together
with
the
significance
level
of
the
>
t=
tests
and
the
test
for
linear
trend.

Normality
of
distribution
was
examined
using
a
Shapiro­
Wilk
test,
while
homogeneity
of
variance
was
assessed
by
plotting
the
residuals
against
the
predicted
values
for
the
model.
If
there
was
significant
non­
normality
that
could
not
be
resolved
by
transforming
the
data,
the
data
was
analyzed
excluding
outliers.
If
the
omission
of
outliers
had
no
effect
on
the
conclusions,
the
results
of
the
full
data
set
only
were
reported.

Descriptive
statistical
methods
were
used
to
summarize
demographic
details,
electrocardiogram
urinalysis,
and
adverse
events
by
dose
level
and,
where
appropriate,
by
timepoint.
Adverse
events
were
summarized
under
each
dose
level
by
tabulating
the
frequency
of
reports
of
each
unique
event,
and
by
tabulating
the
number
of
volunteers
experiencing
one
or
more
events
(
as
classified
by
the
WHO
Adverse
Reaction
Terminology).

II.
RESULTS:

A.
CLINICAL
OBSERVATIONS:

1.
Individual
cholinesterase
inhibition:
Four
volunteers
throughout
the
4
Sessions
demonstrated
a
greater
than
­
40%
inhibition
of
RBC
cholinesterase
activity
from
that
individuals
baseline
(
baseline
consisted
of
the
mean
of
16
hours
pre­
dosing
and
30
minutes
pre­
dosing;
or
when
one
value
was
missing,
consisted
of
the
single
pre­
dose
value).
In
Session
1,
one
volunteer
receiving
0.1
mg/
kg
had
approximately
­
43.5%
RBC
cholinesterase
inhibition
(
from
self
baseline)
8
hours
post­
dosing.
In
Session
2,
one
volunteer
receiving
0.2
mg/
kg
had
approximately
­
40.6%
RBC
cholinesterase
inhibition
(
from
self
baseline)
at
45
minutes
post­
dosing.
This
individual
also
reported
a
single
occurrence
of
a
headache
(
that
did
not
require
treatment)
105
minutes
after
dosing
but
ended
within
one
hour.
In
Session
3,
at
45
minutes
post­
dose,
one
volunteer
receiving
0.3
mg/
kg
dose
had
approximately
­
43.0%
RBC
cholinesterase
inhibition.
At
this
point
in
the
study,
the
Study
Director
and
the
Sponsor
agreed
a
minimum
effect
level
had
been
reached.
The
study
was
then
unblinded
and
the
data
reviewed.
Since
the
minimum
effect
level
had
been
reached
(
criterion
of
­
40%
or
greater
RBC
cholinesterase
inhibition
),
the
highest
dose
(
0.5
mg/
kg)
in
Session
3
was
dropped.
Subsequently,
Amendment
1
to
the
protocol
was
issued
detailing
that
Session
4
would
consist
of
6
volunteers,
one
receiving
placebo
and
five
receiving
0.2
mg/
kg
of
the
test
compound.
The
study
was
then
re­
blinded.
In
Session
4,
one
volunteer
exhibited
a
­
41%
decrease
in
RBC
cholinsterase
activity
at
75
minutes
post­
dosing.
As
a
result
of
the
RBC
inhibition
in
Session
4,
the
Sponsor
decided
that
no
further
dose
groups
were
required.
METHOMYL/
90301
Ascending
Acute
Oral
Toxicity
Study
(
1998)
Page
8
of
12
Non­
guideline
With
the
exception
of
the
decreased
RBC
cholinesterase
activity
in
the
0.1
mg/
kg
volunteer
(
at
8
hours
post­
dosing),
the
other
3
study
volunteers
had
normal
RBC
cholinesterase
activity
by
6
hours
post­
dosing
(
Table
2).

2.
Group
cholinesterase
inhibition:
The
group
mean
"
standard
deviation
of
plasma
and
RBC
cholinesterase
activity
of
all
volunteers
is
provided
in
Table
3.
Statistical
analysis
of
the
group
mean
by
time
point
was
not
performed.
Instead,
statistical
analysis
was
performed
on
the
percent
change
of
cholinesterase
activity
of
the
baseline
(
individual)
compared
to
placebo.
This
was
exhibited
by
the
difference
of
the
mean
cholinesterase
activity
at
specific
post­
dosing
time
points
with
the
mean
baseline
cholinesterase
activity.
Baseline
is
defined
as
the
mean
of
the
two
pre­
dose
values
(
16h
and
30
min
pre­
dose)
for
each
individual
of
the
dose
group.
If
one
of
the
pre­
dose
values
was
missing
for
an
individual,
baseline
was
taken
as
the
nonmissing
assessment.
The
mean
percent
change
from
baseline
plasma
and
RBC
cholinesterase
activity
for
each
dose
group
is
presented
in
Table
2.
In
addition,
statistical
analysis
including
and
excluding
outliers
was
performed
for
plasma
cholinesterase
activity
only
and
is
also
presented
in
Table
2.

For
plasma
cholinesterase
activity,
the
statistical
significance
was
similar
regardless
of
whether
outliers
where
included
or
excluded
from
the
analysis.
The
mean
percent
change
in
plasma
cholinesterase
activity
(
including
outliers)
was
statistically
significantly
decreased
compared
to
placebo
activity
in
the
high
dose
(
0.3
mg/
kg)
beginning
at
15
minutes
post­
dosing
(­
9.8%)
until
4
hours
post­
dosing
(­
8.1%),
with
peak
inhibition
at
45
minutes
(­
21.1%,
p<
0.001)
and
recovery
at
6
hours
post­
dosing.
In
the
mid­
dose
group
(
0.2
mg/
kg)
the
mean
percent
change
from
mean
baseline
plasma
cholinesterase
activity
(
including
outliers)
compared
to
placebo
was
statistically
significantly
decreased
beginning
at
45
minutes
post­
dosing
(­
11.5%)
until
2
hours
post­
dosing
(­
10.3%)
with
peak
inhibition
at
1
hour
45
minutes
(­
13.5%,
p<
0.001)
and
recovery
at
3
hours
post­
dosing.
Mean
percent
change
in
plasma
cholinesterase
activity
for
the
low
dose
(
0.1
mg/
kg)
was
statistically
similar
to
placebo
activity
at
all
time
points
when
outliers
were
included.
When
outliers
were
excluded,
the
mean
percent
change
in
plasma
cholinesterase
activity
for
the
low
dose
(
0.1
mg/
kg)
at
2
hours
post­
dosing
was
statistically
significant
from
placebo
activity
(­
7.2%).

The
mean
percent
change
in
RBC
cholinesterase
activity
(
including
outliers)
was
statistically
significantly
decreased
compared
to
placebo
from
the
first
time
point
at
15
minutes
(­
18.6%,
p<
0.05)
to
4
hours
post­
dosing
(­
5.0%,
p<
0.05),
with
peak
inhibition
at
45
minutes
(­
35.2%,
p<
0.001)
and
recovery
at
6
hours
post­
dosing
in
the
high­
dose
group
(
0.3
mg/
kg).
At
the
mid­
dose,
mean
percent
change
in
RBC
cholinesterase
activity
(
including
outliers)
was
statistically
significantly
decreased
compared
to
placebo
activity
beginning
at
45
minutes
postdosing
(­
20.0%,
p<
0.05)
until
2
hours
post­
dosing
(­
16.2%,
p<
0.05),
with
peak
inhibition
at
1
hour
and
30
minutes
(­
27.9,
p<
0.001)
and
recovery
at
3
hours
post­
dosing.
The
mean
percent
change
in
RBC
cholinesterase
activity
for
the
low
dose
(
0.1
mg/
kg)
was
statistically
similar
to
placebo
at
all
time
points.
However,
at
60,
75,
and
90
minutes
post­
dose,
the
mean
percent
change
in
RBC
cholinesterase
activity
was
­
14.6%
,
­
19.0%,
and
­
10.5%
below
the
group
mean
baseline
level,
respectively.
This
decrease
in
mean
RBC
cholinesterase
activity
coincides
with
the
inhibition
of
RBC
cholinesterase
activity
in
the
mid­
and
high­
dose
groups.
The
METHOMYL/
90301
Ascending
Acute
Oral
Toxicity
Study
(
1998)
Page
9
of
12
Non­
guideline
statistical
analysis
for
RBC
cholinesterase
activity
was
for
all
volunteers,
the
RBC
analysis
without
outliers
was
not
presented.

TABLE
2.
Plasma
and
RBC
cholinesterase
activity
change
from
baseline
(
mean
"
SD%)
over
time
(
with*
and
withoutC
outliers)
in
volunteers
receiving
methomyl
Dosage
group
(
mg/
kg
bw)

Time
0
0.1
0.2
0.3
Plasma
cholinesterase
15
mins
post­
dose
­
1.31
"
5.0
­
3.07
"
3.6
­
2.46
"
2.8
­
9.76*"
2.
C
30
mins
post­
dose
­
2.87
"
4.8
­
6.64
"
3.9
­
7.87
"
3.7
­
15.85**"
2.2
CC
45
mins
post­
dose
­
1.4
"
3.8
­
5.63
"
2.1
­
11.48*"
5.5
CC
­
21.08**"
4.9
CC
1
h
post­
dose
­
0.31
"
3.0
­
4.52
"
3.4
­
11.03*"
4.2
CC
­
16.59**"
2.2
CC
1
h
15
mins
post­
dose
­
0.79
"
4.7
­
2.95
"
5.7
­
13.32**"
5.1
CC
­
19.67**"
2.9
CC
1
h
30
mins
post­
dose
­
2.42
"
5.7
­
5.91
"
3.9
­
12.90*"
2.5
CC
­
14.84**"
4.2
CC
1
h
45
mins
post­
dose
­
2.67
"
4.8
­
5.57
"
1.8
­
13.52*"
2.0
CC
­
15.89**"
3.8
CC
2
h
post­
dose
­
0.99
"
3.8
­
7.22
"
3.6
C
­
10.34*"
3.3
C
­
14.12**"
5.6
CC
3
h
post­
dose
­
1.29
"
4.8
­
1.07
"
4.7
­
5.04
"
4.6
­
10.87*"
3.0
CC
4
h
post­
dose
0.02
"
7.3
­
2.51
"
2.1
­
1.26
"
3.2
­
8.11*"
3.8
C
6
h
post­
dose
0.56
"
6.4
­
0.18
"
3.8
2.06
"
5.0
0.24
"
3.1
RBC
cholinesterase
15
mins
post­
dose
5.83
"
9.8
3.15
"
17.5
­
1.19
"
9.3
­
18.57*"
12.4
30
mins
post­
dose
­
1.78
"
5.6
­
9.2
"
13.0
­
12.42
"
5.6
­
31.96**"
3.6
45
mins
post­
dose
­
2.93
"
14.9
­
2.45
"
12.1
­
19.98*"
14.1
­
35.25**"
10.4
1
h
post­
dose
­
3.98
"
17.3
­
14.61
"
11.6
­
24.71*"
9.4
­
27.28*"
7.5
1
h
15
mins
post­
dose
­
4.26
"
5.8
­
19.04
"
9.3
­
27.59*"
10.7
­
26.79*"
7.3
1
h
30
mins
post­
dose
­
0.3
"
5.6
­
10.5
"
10.6
­
27.87**"
7.4
­
23.20*"
7.4
1
h
45
mins
post­
dose
1.82
"
5.9
­
3.57
"
11.5
­
22.19*"
4.9
­
22.41*"
10.7
2
h
post­
dose
5.84
"
14.0
­
8.91
"
11.2
­
16.20*"
5.6
­
16.02*"
8.7
3
h
post­
dose
12.06
"
12.7
­
2.13
"
12.5
­
1.34
"
7.4
­
12.90*"
16.5
4
h
post­
dose
11.35
"
10.1
4.97
"
12.3
­
2.28
"
8.8
­
5.05*"
8.5
6
h
post­
dose
6.22
"
12.8
­
5.89
"
16.3
14.75
"
6.4
­
1.99
"
6.7
Data
obtained
from
pp.
432­
433,
and
436­
437,
MRID
44721401.
With
Outliers:
*
Statistically
significant
at
p
<
0.05,
compared
with
controls.
**
Statistically
significant
at
p
#
0.001,
compared
with
controls.
Without
Outliers:
CStatistically
significant
at
p
<
0.05,
compared
with
controls.
CCStatistically
significant
at
p
#
0.001,
compared
with
controls.
mins
=
minutes,
h
=
hours
METHOMYL/
90301
Ascending
Acute
Oral
Toxicity
Study
(
1998)
Page
10
of
12
Non­
guideline
Baseline
is
defined
as
the
mean
of
the
two
pre­
dose
values
(
16h
and
30
min
pre­
dose)
for
each
individual
of
the
dose
group.
If
one
of
the
pre­
dose
values
was
missing
for
an
individual,
baseline
was
taken
as
the
non­
missing
assessment.
The
mean
baseline
value
for
the
group
was
used
to
determine
the
%
change
from
baseline.
METHOMYL/
90301
Ascending
Acute
Oral
Toxicity
Study
(
1998)
Page
11
of
12
Non­
guideline
TABLE
3.
Mean
Plasma
and
RBC
cholinesterase
activity
(
mean
"
standard
deviation)
over
time
in
all
volunteers
receiving
methomyl
Dosage
group
(
mg/
kg
bw)

Time
0
0.1
0.2
0.3
Plasma
cholinesterase
16
h
pre­
dose
5532.5
"
744
5265.8
"
942.5
5535.4
"
844.1
5658.6
"
574.0
30
mins
pre­
dose
5588.8
"
663.4
5273.6
"
938.6
5272.8
"
591.9
5664.8
"
533.7
15
mins
post­
dose
5480.5
"
644.4
5085.6
"
755.5
5264.2
"
631.5
5115.8
"
574.2
30
mins
post­
dose
5402.0
"
715.8
4913.2
"
859.0
4971.6
"
613.3
4763.8
"
458.4
45
mins
post­
dose
5487.0
"
737.0
4981.0
"
943.9
4777.0
"
606.7
4458.6
"
388.4
1
h
post­
dose
5537.0
"
622.4
5044.4
"
994.6
4789.2
"
470.0
4714.6
"
353.6
1
h
15
mins
post­
dose
5515.8
"
699.8
5119.2
"
965.2
4660.6
"
420.3
4555.6
"
536.6
1
h
30
mins
post­
dose
5427.3
"
728.8
4952.2
"
857.2
4697.4
"
533.3
4837.6
"
675.1
1
h
45
mins
post­
dose
5420.0
"
770.4
4967.8
"
831.7
4671.4
"
605.4
4774.0
"
642.5
2
h
post­
dose
5504.8
"
685.0
4887.0
"
888.2
4833.6
"
549.2
4879.8
"
718.0
3
h
post­
dose
5505.5
"
868.7
5218.2
"
973.7
5115.4
"
561.0
5054.6
"
612.8
4
h
post­
dose
5580.0
"
927.9
5145.2
"
976.8
5326.6
"
622.3
5218.6
"
717.2
6
h
post­
dose
5584.5
"
691.3
5250.6
"
872.4
5286.2
"
682.1
5683.0
"
647.8
8
h
post­
dose
5580.0
"
797.6
5224.0
"
788.2
5430.6
"
685.3
5611.0
"
544.8
12
h
post­
dose
5377.5
"
675.5
5210.4
"
828.0
5366.6
"
700.7
6091.6
"
699.8
24
h
post­
dose
5602.0
"
523.1
5366.8
"
808.4
5432.6
"
792.5
5877.6
"
951.2
RBC
cholinesterase
16
h
pre­
dose
11294.3
"
1597.5
9568.8
"
2033.1
11515.2
"
1453.0
10785.6
"
730.1
30
mins
pre­
dose
11749.5
"
1807.1
10345.2
"
1926.0
12102.0
"
1177.5
11173.8
"
1013.8
15
mins
post­
dose
12092.3
"
1158.1
10057.2
"
986.3
11656.2
"
1464.4
8978.4
"
1702.4
30
mins
post­
dose
11372.3
"
2122.6
8954.4
"
1537.6
10331.4
"
1184.8
7454.4
"
253.1
45
mins
post­
dose
11049.8
"
1285.8
9745.8
"
2441.4
9409.8
"
1599.0
7119.6
"
1267.5
1
h
post­
dose
10997.3
"
2267.7
8412.6
"
1318.6
8865.0
"
1266.2
7978.2
"
909.9
1
h
15
mins
post­
dose
11077.5
"
2151.6
7959.6
"
959.4
8522.4
"
1388.6
8044.8
"
1020.0
1
h
30
mins
post­
dose
11420.3
"
1142.1
8821.8
"
1384.6
8475.0
"
894.6
8416.8
"
780.0
1
h
45
mins
post­
dose
11683.5
"
1449.5
9467.4
"
1166.6
9140.4
"
444.6
8552.4
"
1556.5
2
h
post­
dose
12036.0
"
782.0
8972.4
"
1348.3
9843.0
"
511.8
9225.0
"
1197.0
3
h
post­
dose
12766.5
"
926.0
9731.4
"
2117.0
11616.6
"
1126.4
9651.0
"
2333.6
4
h
post­
dose
12716.3
"
1073.0
10424.0
"
2100.6
11475.0
"
833.2
10467.6
"
1532.6
6
h
post­
dose
12250.5
"
2561.9
9186.6
"
925.7
13508.4
"
1094.0
10789.8
"
1300.7
8
h
post­
dose
11193.8
"
3226.8
8752.2
"
1273.6
12880.8
"
1582.2
10948.2
"
1125.1
METHOMYL/
90301
Ascending
Acute
Oral
Toxicity
Study
(
1998)
Page
12
of
12
Non­
guideline
TABLE
3.
Mean
Plasma
and
RBC
cholinesterase
activity
(
mean
"
standard
deviation)
over
time
in
all
volunteers
receiving
methomyl
Dosage
group
(
mg/
kg
bw)

Time
0
0.1
0.2
0.3
Plasma
cholinesterase
12
h
post­
dose
10914.8
"
2944.2
8212.2
"
582.7
13461.0
"
1162.3
10411.8
"
1791.3
24
h
post­
dose
11155.5
"
3277.6
9324.0
"
458.6
12946.8
"
1450.5
10843.8
"
1203.2
Data
obtained
from
pp.
438­
441,
and
442­
445,
MRID
44721401.

3.
Increased
salivation:
A
comparison
of
group
mean
saliva
weight
at
the
various
time
points
(
excluding
outliers)
showed
no
dose
response,
except
at
one
hour
(
control
to
high­
dose:
­
13.5,
38.7,
50.3,
and
60.3%
[
p=
0.009]
change
from
baseline
(
individual),
respectively).
However,
data
was
not
collected
or
reported
for
fluid
intake
after
dosing
which
may
have
helped
explain
the
difference
in
salivation
at
the
one
hour
time
point.

TABLE
4.
Percent
change
from
baseline
of
saliva
weight
as
mean
"
standard
deviation
over
time
for
volunteers
receiving
methomyl
(
with
and
without
outliers)

Dosage
group
(
mg/
kg
bw)

0
mg/
kg
0.1
mg/
kg
0.2
mg/
kg
0.3
mg/
kg
Time
mean"
SD
%
change
mean"
SD
%
change
mean"
SD
%
change
mean"
SD
%
change
Saliva
Weight
1
h
post­
dose
2.28"
1.29
­
13.5"
6.98
1.36"
1.54
38.7"
70.8
1.78"
1.46
50.3"
65.8
2.48"
0.93
60.3"
26.6C
2
h
post­
dose
2.00"
0.95
­
16.5"
20.55
1.2"
1.17
16.1"
34.9
2.00"
1.90
49.5"
50.4C
1.58"
0.68
1.10"
29.2
3
h
post­
dose
1.68"
0.63
­
26.69"
23.27
1.14"
1.29
3.4"
34.6
1.80"
1.41
53.8"
66.5C
1.52"
0.43
­
0.4"
12.3
4
h
post­
dose
2.58"
1.34
4.41"
22.74
1.14"
1.41
0.9"
57.0
2.04"
1.67
44.6"
55.2
1.60"
0.76
2.3"
28.7
8
h
post­
dose
1.9"
1.20
­
17.42"
35.41
1.48"
1.53
35.0"
39.8
2.26"
1.84
70.3"
83.8*
C
1.44"
0.82
­
7.1"
45.8
24
h
postdose
2.43"
1.31
1.81"
37.78
1.2"
1.31
8.9"
41.4
1.48"
1.42
59.4"
165.1
1.38"
0.71
­
10.8"
26.9
*
Statistically
significant
at
p
<
0.05,
compared
with
controls
(
including
outliers)
CStatistically
significant
at
p
<
0.05,
compared
with
controls
(
excluding
outliers)

4.
Pupillary
size:
There
were
no
significant
differences
in
the
changes
from
baseline
in
the
initial
pupil
size,
minimum
pupil
size,
or
recovery
pupil
size
for
any
of
the
dose
groups
of
methomyl
compared
with
placebo.

B.
CLINICAL
CHEMISTRY:
There
were
no
statistical
significant
changes
in
any
of
the
mean
clinical
chemistry
indices
with
any
dose
of
methomyl
from
­
30
minutes
to
+
24
hours.

Increased
total
bilirubin:
On
the
individual
level,
three
volunteers
had
total
bilirubin
concentrations
above
the
normal
range.
One
0.1
mg/
kg
volunteer
had
increased
total
bilirubin
at
30
minutes
pre­
dosing
(
31.4
µ
mol/
L);
one
0.2
mg/
kg
volunteer
had
increased
METHOMYL/
90301
Ascending
Acute
Oral
Toxicity
Study
(
1998)
Page
13
of
12
Non­
guideline
total
bilirubin
values
at
screening
(
28.5
µ
mol/
L),
30
minutes
pre­
dose
(
29.0
µ
mol/
L),
and
24
hours
post­
dosing
(
21.7
µ
mol/
L);
and
one
0.3
mg/
kg
volunteer
had
increased
total
bilirubin
values
(
clinical
chemistry
parameters
for
this
individual
were
checked
twice
at
screening),
(
42.2
and
47.4
µ
mol/
L,
respectively),
30
minutes
pre­
dose
(
47.3
µ
mol/
L),
and
24
hours
post­
dosing
(
56.9
µ
mol/
L).

C.
BODY
WEIGHT:
Body
weight
was
not
evaluated
in
this
acute
study.

III.
DISCUSSION
AND
CONCLUSIONS:

A.
INVESTIGATORS
=

CONCLUSIONS:
A
Under
the
conditions
of
this
study
and
based
on
the
absence
of
any
clinical
signs
of
cholinergic
stimulation,
ECG
analysis,
pulse,
respiratory
rate,
or
any
statistical
increases
in
salivation,
pupillary
responses,
hematology,
clinical
chemistry,
or
statistically
significant
RBC
or
plasma
ChE
activities,
the
no­
observed­
adverseeffect
level
(
NOAEL)
for
humans
after
a
single
oral
dose
of
methomyl
is
0.1
mg.
kg
­
1
of
body
weight.
A
B.
EPA
CONCLUSION:

No
dose
group
had
changes
in
pupillary
size,
respiratory
rate,
ECGs,
vital
signs,
hematology,
clinical
chemistry,
urinalysis,
or
clinical
signs
(
with
the
exception
of
the
0.3
mg/
kg
individual
who
complained
of
a
transient
headache).
A
dose­
response
relationship
was
observed
in
all
dose
groups
for
plasma
and
RBC
cholinesterase
activity.
In
addition,
cholinesterase
activity
for
both
plasma
and
RBC
was
consistent
for
timing
of
peak
effect
and
time
to
recovery.
Inhibition
of
ChE
activity
for
both
plasma
and
RBC
ranged
from
­
19%
to
­
35%
at
the
high
dose
(
0.3
mg/
kg)
to
­
20%
to
­
28%
at
the
mid
dose
(
0.2
mg/
kg).
RBC
cholinesterase
activity
was
decreased
by
19%
in
the
0.1
mg/
kg
group
(
non­
statistically)
at
75
minutes
post­
dosing,
which
coincides
with
the
timing
of
peak
RBC
cholinesterase
inhibition
of
the
mid­
and
highdose
groups.
Plasma
and
RBC
cholinesterase
activity
typically
returned
to
normal
by
6
hours
post­
dosing
in
all
dose
groups.
Therefore,
the
NOAEL
for
humans
after
a
single
oral
dose
of
methomyl
is
<
0.1
mg/
kg.

In
addition,
the
Agency
used
the
RBC
ChE
inhibition
and
recovery
data
for
input
into
the
Agency
=

s
BMDS
model.
The
BMD10
is
0.035
mg/
kg
and
BMDL10
is
0.015
mg/
kg.
The
BMD
and
BMDL
estimates
were
considered
for
the
NMC
carbamate
cumulative
risk
assessment
for
refinement
of
the
interspecies
extrapolation
factor
for
methomyl.

C.
DEFICIENCIES:
There
were
no
study
deficiencies
identified
that
would
have
affected
the
outcome
and
conclusions
of
this
study.
