1
January
31,
2003
MEMORANDUM
SUBJECT:
Atrazine:
Addendum
to
Revised
Occupational
and
Residential
Exposure
Assessment
and
Recommendations
for
the
Reregistration
Eligibility
Decision
Document
(
dated
August
30,
2002).
PC
Code:
080803.
DP
Barcode:
D287742
FROM:
Catherine
Eiden,
Branch
Senior
Scientist
Reregistration
Branch
3
Health
Effects
Division
THROUGH:
Donna
Davis,
Branch
Chief
Reregistration
Branch
3
Health
Effects
Division
TO:
Kimberly
Lowe,
Chemical
Review
Manager
Special
Review
and
Reregistration
Division
Please
find
attached
an
addendum
to
HED's
Revised
Occupational
and
Residential
Exposure
Assessment
and
Recommendations
for
the
Reregistration
Eligibility
Decision
Document
(
dated
August
30,2002).
This
addendum
includes
an
assessment
of
any
new
information
and
data
submitted
to
the
Agency
during
the
60­
day
public
comment
period.
Any
changes
in
the
outcome,
updates,
or
revisions
to
the
document
are
reflected
in
this
addendum.
The
revised
occupational
and
residential
exposure
assessment
document
(
8/
30/
02)
and
this
addendum
should
be
considered
together.
2
Background:

HED
provides
this
addendum
to
the
Revised
Occupational
and
Residential
Exposure
Assessment
and
Recommendations
for
the
Reregistration
Eligibility
Decision
Document
(
the
revised
ORE
chapter)
dated
August
30,
2002
to
correct
and
revise
the
document
prior
to
issuance
of
the
Interim
Reregistration
Eligibility
Decision
(
IRED)
for
atrazine.
This
addendum
includes
changes
to
the
short­
term
aggregate
post­
application
risk
assessments
based
on
discussion
with
the
registrant
(
Sipcam)
and
revisions
reflecting
current
policies.
This
addendum
should
be
read
in
conjunction
with
the
August
30,
2002
chapter.

Dermal
Absorption
Factor
Typo
Correction:

Page
35
of
the
August
30,
2002
revised
ORE
chapter
contains
the
following
sentence:
"
The
short­
term
exposure
assessment
does
not
require
use
of
a
dermal
absorption
factor
since
the
toxicity
endpoint
is
based
on
21­
day
dermal
study".
This
sentence
is
incorrect
and
should
have
been
deleted
from
the
revised
ORE
chapter.
All
short­
term
dermal
risk
assessments
for
atrazine
use
an
endpoint
from
a
28­
day
oral
study
in
the
rat.
Therefore,
a
dermal
absorption
factor
is
required
to
extrapolate
from
an
oral
endpoint
for
the
purposes
of
dermal
risk
assessment.
The
dermal
absorption
factor
used
in
the
dermal
risk
assessments
was
6%.

Post­
application
Dermal
Exposure
and
Risk
Estimates:

HED
has
recalculated
post­
application
dermal
exposure
and
risk
estimates
for
homeowners
(
adults
and
children)
for
liquid
applications
of
atrazine
to
turf.
Table
15
summarizes
these
results.

A
total
of
8
dermal
postapplication
exposure
scenarios
were
evaluated.
All
of
these
scenarios,
involving
exposure
following
application
of
liquid
or
granular
formulations,
had
short­
term
dermal
MOEs
greater
than
300,
for
high­
contact
activities
on
turf
for
children
and
adults.
The
lowest
MOEs
of
310
for
children
and
510
for
adults
are
based
on
average
residues
for
the
day
of
application
at
two
sites
(
NC
and
GA)
each
receiving
liquid
formulations
at
2
lbs
ai/
A.
Residues
had
dissipated
sufficiently
on
the
day
after
treatment
to
raise
MOEs
for
children
to
750
and
adults
to
1300.
For
adults
golfing
and
mowing
on
treated
turf,
all
short­
term
dermal
MOEs
exceeded
300.

Adults
may
reasonably
be
expected
to
perform
more
than
one
activity
on
treated
lawns
in
a
single
day,
but
an
eight­
hour
duration
of
exposure
is
unlikely.
Therefore,
it
is
reasonable
to
aggregate
the
exposures
from
playing/
gardening
(
highest
exposure
rate),
walking,
and
mowing
(
lower
exposure
rate)
for
a
single
MOE.
The
MOE
for
all
adult
post­
application
exposures
aggregated
from
liquid
applications
at
2
lbs
ai/
A
is
460
and
does
not
exceed
HED's
3
level
of
concern.
It
is
also
possible
that
an
adult
would
apply
herbicide
spray
to
a
lawn
and
then
play
on
it
or
mow
it
later
that
day.
In
such
an
event,
the
aggregated
dermal
MOE
for
the
day
would
be
slightly
lower
than
the
target
300
for
that
day.
Based
on
the
liquid
application
(
2
lbs
ai\
A)
study
residue
values
for
adult
handler
and
adult
post­
application
exposures,
the
aggregate
MOE
for
dermal
exposures
is
270.
[
See
table
14b
from
the
August
30,
2002
document
(
1/[
1/
460
+
1/
640]
=
270)].
However,
this
aggregate
exposure
scenario
is
not
very
likely
and
is
considered
a
high­
end
estimate
of
exposure.
Aggregate
risk
estimates
for
adults
applying
and
playing
on
treated
lawns
based
on
the
granular
residue
data
do
not
exceed
HED's
level
of
concern.

If
the
liquid
formulation
application
rates
are
reduced
to
1
lb
ai/
A,
the
resulting
MOE
for
estimates
of
dermal
exposures
result
in
a
MOE
of
610
for
children
and
greater
than
1000
for
adults.
Combined
dermal
exposures
for
adults
at
a
1
lb
ai/
a
rate
result
in
a
risk
estimate
of
860
that
does
not
exceed
HED's
level
of
concern.

Table
15
should
now
read:

Table
15.
Residential
Short­
term
Dermal
Postapplication
Risks
for
Atrazine
(
Using
TTR
values
from
liquid
and
granular
Atrazine
turf
studies
­
MRID
Nos.
449580­
01,
449588­
01)

Dermal
Scenarios
Exposu
re
Time
(
hours
/
day)
Short
Term
Risks
Transfe
r
Coeffic
ient
a
(
cm
2/
hr
)
MOEs
c
GA
granular
GA/
NC
liquid
(
Avg.)
FL
granular
Nonirrig
Irrig
.
Nonirrig
Irrig.

Adult
dermal
turf
contact
2
14,500
4300
3400
510
(
2
lb
ai/
A)
1000
(
1
lb
ai/
A)
1200
21,000
Child
dermal
turf
contact
2
5,200
2600
2000
310
(
2
lb
ai/
A)
610
(
1
lb
ai/
A)
690
13,000
Table
15.
Residential
Short­
term
Dermal
Postapplication
Risks
for
Atrazine
(
Using
TTR
values
from
liquid
and
granular
Atrazine
turf
studies
­
MRID
Nos.
449580­
01,
449588­
01)

Dermal
Scenarios
Exposu
re
Time
(
hours
/
day)
Short
Term
Risks
Transfe
r
Coeffic
ient
a
(
cm
2/
hr
)
MOEs
c
GA
granular
GA/
NC
liquid
(
Avg.)
FL
granular
Nonirrig
Irrig
.
Nonirrig
Irrig.

4
Adult
walking,
playing
golf
4
500
62,000
49,00
0
7400
(
2
lb
ai/
A)
14,800
(
1
lb
ai/
A)
17,000
310,00
0
Adult
push
mowing
lawn
2
500
120,00
0
98,00
0
15,000
(
2
lb
ai/
A)
30,000
(
1
lb
ai/
A)
34,000
620,00
0
a
Transfer
coefficient
from
revisions
to
Residential
SOP's
(
02/
01).
b
TTR
source:
liquid
and
granular
turf
studies
MRID
#
449580­
01,
449588­
01,
DAT
0­
1
residue
(
see
Table
9).
The
average
DAT
0
residue
was
used
and
calculated
from
2
sites
across
2
time
points
for
each
site
(
0
and
0.5
days
).
All
formulations
in
the
studies
were
applied
at
a
rate
of
2
lb
ai/
acre.
c
MOE
=
Short­
term
NOAEL
(
104
mg/
kg/
day)
/
dermal
dose
where
dermal
dose
=
TTR
(
µ
g/
cm
2)
x
TC
(
cm
2/
hr)
x
conversion
factor
(
1
mg/
1,000
µ
g)
x
exposure
time
(
2
hrs/
day)
/
body
weight
(
70
kg
adult
or
15
kg
1­
to
6­
yearold

Notes:
TTR
=
Turf
Transferable
Residue.
Short­
term
NOAEL
of
104
mg/
kg/
day
reflects
6%
dermal
absorption
factor
applied
to
6.25
mg/
kg/
day
short­
term
oral
endpoint.

Post­
application
Incidental
Oral
Exposure
and
Risk
Estimates:

HED
has
recalculated
post­
application
incidental
oral
exposure
and
risk
estimates
for
children
for
liquid
applications
of
atrazine
to
5
turf.
Table
15
summarizes
these
results.
At
the
2
lb
ai/
A
application
rate,
incidental
oral
(
non­
dietary)
risk
estimates
exceed
HED's
level
of
concern
for
toddlers
incidental
oral
exposures
on
lawns
treated
with
liquid
formulations.
Risk
estimates
are
210
for
hand­
to­
mouth
activity
and
200
for
combined
oral
(
non­
dietary)
exposures.
Risk
estimates
do
not
exceed
HED's
level
of
concern
for
toddlers
incidental
oral
exposures
on
lawns
treated
with
granular
formulations.
Risk
estimates
are
950
for
hand­
to­
mouth
activity
and
730
for
combined
oral
(
non­
dietary)
exposures.

If
the
liquid
formulation
application
rates
are
reduced
to
1
lb
ai/
A,
the
resulting
MOE
for
toddlers'
hand­
to­
mouth
exposures
is
420,
and
does
not
exceed
HED's
levels
of
concern.
Combined
incidental
oral
exposures
for
toddlers
result
in
a
MOE
of
390
and
do
not
exceed
HED's
levels
of
concern.

Combined
Dermal
and
Incidental
Oral
Exposures
for
Children:

It
is
considered
reasonably
likely
that
dermal
and
oral
incidental
exposures
may
occur
in
the
same
day
for
children
playing
on
atrazine­
treated
lawns.
It
can
be
seen
from
calculations
presented
in
Table
17
that
the
incidental
hand­
to­
mouth
exposure
estimate
constitutes
most
of
the
total
non­
dietary
oral
dose.
The
overall
incidental
oral
MOE
is
only
slightly
less
(
200
for
spray,
730
for
granular)
than
the
MOE
for
the
hand­
to­
mouth
estimate
(
210
spray;
950
granular).
The
individual
dermal
and
oral
routes
of
exposure
on
sprayed
turf
each
exceed
the
level
of
concern,
and
adding
them
mathematically
produces
an
even
lower
MOE
of
125,
while
the
granular
total
MOE
for
dermal
+
oral
incidental
exposure
is
at
least
350.
These
route­
specific
and
dermal
+
oral
aggregated
doses
and
MOEs
were
calculated
for
the
purposes
of
the
overall
risk
assessment
for
this
chemical,
which
will
consider
all
routes
of
exposure.
Finally,
ingestion
of
granules,
as
explained
earlier,
is
not
aggregated
because
it
is
considered
an
infrequent,
episodic
event.

At
1
lb
ai/
A
risk
estimates
for
liquid
formulations
for
dermal
exposures
result
in
a
MOE
of
610
for
children.
At
1
lb
ai/
A
for
liquid
formulations,
combined
dermal
and
incidental
oral
exposures
for
toddlers
(
1/[
1/
610
+
1/
390])
result
in
a
MOE
of
240
for
toddlers'
aggregate
dermal
and
oral
exposures,
a
highly
conservative
risk
estimate,
which
is
slightly
lower
than
300.
6
Table
17
should
read
as
follows:

Table
17.
Residential
Short­
term
Oral
Nondietary
Postapplication
Risks
to
Children
(
1­
6)
from
"
Hand­
to­
Mouth"
and
Ingestion
Exposure
When
Reentering
Lawns
Treated
with
Granular
or
Liquid
Atrazine
Formulations
Type
of
Exposure
Appli
catio
n
Rate
a
(
lb
ai/
ac
re)
Ingestion
Rate
or
Other
Assumptions
b
Oral
Dose
c
(
mg/
kg/
d
ay)
MOE
d
Hand
to
Mout
h
Acti
vity
liqui
d
2
Residential
SOPs
0.030
0.015
(
1
lb
ai/
A)
210
420
granu
lar
Atrazine
Granular
Hand­
Press
Study
0.0066
950
Turfgrass/
O
bject
Mouthing
2
liqui
d
or
granu
lar
Residential
SOPs
0.0019
3300
1
liqui
d
Residential
SOPs
9.5
x
10­
4
6600
Ingestion
of
Soil
2
liqui
d
or
granu
lar
Residential
SOPs
1.0E­
4
62,50
0
1
liqui
d
Residential
SOPs
5
x
10­
5
130,0
00
Total
of
the
Oral
Exposures
Above
e
Liquid
formulation
0.032
(
2
lb
ai/
A)
0.016
(
1
lb
ai/
A)
200
390
Granular
formulation
0.0086
730
Incidental
Ingestion
of
Granules
0.42%
ai
0.2­
0.4
g/
day
(
100­
200
lbs
formulation
/
acre)
0.056­
0.11
57­
110
1.5%
ai
0.2­
0.4
16­
31
Table
17.
Residential
Short­
term
Oral
Nondietary
Postapplication
Risks
to
Children
(
1­
6)
from
"
Hand­
to­
Mouth"
and
Ingestion
Exposure
When
Reentering
Lawns
Treated
with
Granular
or
Liquid
Atrazine
Formulations
Type
of
Exposure
Appli
catio
n
Rate
a
(
lb
ai/
ac
re)
Ingestion
Rate
or
Other
Assumptions
b
Oral
Dose
c
(
mg/
kg/
d
ay)
MOE
d
7
Footnotes:

a
Application
rates
represent
maximum
label
rates
from
current
EPA
registered
labels
of
2
lb
ai/
A.
b
Assumptions
from
Draft
Residential
SOP's
(
1997,
revised
2/
01).

c
Oral
doses
calculated
using
formulas
presented
in
the
Residential
SOPs
(
December,
1999).
Short­
term
doses
were
calculated
using
the
following
formulas.
Hand­
to­
mouth;
in
the
absence
of
DFR
data,
Revised
Residential
SOPs
(
02/
01)
are
used:
oral
dose
to
child
(
1­
6
year
old)
on
the
day
of
treatment
(
mg/
kg/
day)
=
[
application
rate
(
lb
ai/
acre)
x
fraction
of
residue
dislodgeable
with
potentially
wet
hands
(
5%)
x
11.2
(
conversion
factor
to
convert
lb
ai/
acre
to
µ
g/
cm
2)]
x
median
surface
area
for
1­
3
fingers
(
20
cm
2/
event)
x
hand­
to­
mouth
rate
(
ST:
20
events/
hour)
x
50%
saliva
extraction
factor
x
exp.
time
(
2
hr/
day)
x
0.001
mg/
g]
/
bw
(
15
kg
child
).
For
granular
formulations,
the
atrazine
granular
hand­
press
study
data
(
MRIDs
45622310,
45622311)
were
used:
the
average
moistened
hand­
mouth
granular
residue
transfer
rate
of
1.1%
of
the
ai
application
rate.
Grass/
object
mouthing;
oral
dose
to
child
(
1­
6
year
old)
on
the
day
of
treatment
(
mg/
kg/
day)
=
[
application
rate
(
lb
ai/
acre
x
11.2
(
conversion
factor
to
convert
lb
ai/
acre
to
µ
g/
cm
2))
x
fraction
of
residue
dislodgeable
(
5%)
x
ingestion
rate
of
grass
(
25
cm
2/
day)
x
.001
mg/
g]
/
bw
(
15
kg
child
).
Soil
ingestion;
oral
dose
to
child
(
1­
6
year
old)
on
the
day
of
treatment
(
mg/
kg/
day)
=
[(
application
rate
(
lb
ai/
acre)
x
fraction
of
residue
retained
on
uppermost
1
cm
of
soil
(
100%
or
1.0/
cm)
x
4.54E+
08
µ
g/
lb
conversion
factor
x
2.47E­
08
acre/
cm
2
conversion
factor
x
0.67
cm
3/
g
soil
conversion
factor)
x
100
mg/
day
ingestion
rate
x
1.0E­
06
g/
µ
g
conversion
factor]
/
bw
(
15
kg).
Short
term
dose
based
residue
on
the
soil
on
day
of
application.
Granular
pellet
ingestion:
(
mg/
kg/
day)
oral
dose
to
child
(
1­
6
year
old)
=
[
Granule
ingestion
rate
(
0.2­
0.4
g/
day)
x
Fraction
of
ai
of
granule
formulations
x
1,000
mg/
g]
/
bw
(
15
kg).
d
Oral
MOE
=
Oral
NOAEL
(
6.25
mg/
kg/
day
for
short­
term
assessments)
/
Oral
Dose
(
mg/
kg/
day).
Oral
NOAEL
determined
from
a
rat
study.
MOEs
are
reported
to
two
significant
figures;
target
MOE
is
at
least
300.
