Page
1
of
4
UNITED
STATES
ENVIRONMENTAL
PROTECTION
AGENCY
WASHINGTON,
D.
C.
20460
OFFICE
OF
PREVENTION,
PESTICIDES
AND
TOXIC
SUBSTANCES
May
18,
2006
MEMORANDUM
SUBJECT:
Inorganic
Chlorates:
Addendum
to
the
Occupational
and
Residential
Exposure
Assessment
for
the
Reregistration
Eligibility
Decision
(
RED)
Document
(
Case
4049)

PC
Codes:
Sodium
Chlorate:
073301
Potassium
Chlorate:
073302
Calcium
Chlorate:
073303
Magnesium
Chlorate:
530200
FROM:
Matthew
Crowley,
Environmental
Protection
Specialist
Reregistration
Branch
4
Health
Effects
Division
THRU:
Susan
Hummel,
Senior
Scientist
Reregistration
Branch
4
Health
Effects
Division
TO:
Molly
Clayton,
Chemical
Review
Manager
Reregistration
Branch
3
Special
Review
and
Reregistration
Division
DP
Barcode(
s):
D328930
The
attached
document
is
an
addendum
to
the
Health
Effects
Division
(
HED)
chapter
for
the
inorganic
chlorates
RED
Document.
It
updates
the
occupational
and
residential
exposure
(
ORE)
section
following
comments
received
regarding
non­
agricultural
uses
from
the
chemical
registrants
and
a
product
formulator
during
the
RED
process.
Page
2
of
4
1.0
Executive
Summary
Sodium
chlorate,
potassium
chlorate,
calcium
chlorate,
and
magnesium
chlorate
are
included
in
this
RED
case
(
4049),
however
sodium
chlorate
is
the
only
chemical
assessed,
as
it
is
the
only
inorganic
chlorate
present
in
any
registered
products
as
an
active
ingredient
(
ai).
This
document
is
an
addendum
to
the
previous
ORE
assessment
for
the
RED
chapter
(
D307365)
in
which
all
uses
of
sodium
chlorate
were
assessed:
as
both
an
agricultural
defoliant/
desiccant
and
as
a
nonselective
commercial
and
residential
herbicide.

The
purpose
of
this
document
is
to
present
revised
risks
for
occupational
handlers
(
i.
e.,
pesticide
mixers,
loaders,
and
applicators)
based
on
comments
during
the
RED
process
from
the
registrants
and
a
product
formulator
concerning
the
use
pattern
(
i.
e.,
application
rates,
target
sites,
and
amount
treated)
for
the
non­
selective
herbicidal
uses.
The
use
of
sodium
chlorate
as
a
non­
selective
herbicide
can
be
characterized
as
a
spot
treatment
use
as
opposed
to
a
broadcast
application.
Standard
HED
assumptions
for
amount
of
area
treated
per
day
based
on
the
equipment
used
greatly
overestimate
areas
treated
with
sodium
chlorate.
Therefore,
risk
calculations
have
been
developed
to
better
represent
the
use
pattern
for
sodium
chlorate.

Risk
estimates
presented
in
this
document
supersede
those
presented
in
the
previous
assessment
for
the
non­
selective
herbicidal
use
of
sodium
chlorate
in
non­
agricultural/
industrial
settings
which
included
additional
equipment
and
larger
daily
areas
treated.
Risk
estimates
for
all
other
scenarios
(
i.
e.,
occupational
and
residential)
previously
assessed
remain
unchanged.

All
risk
estimates
presented
in
this
addendum
are
not
of
concern
(
Margins
of
Exposure
(
MOEs)
>
100)
at
baseline
(
i.
e.,
no
respiratory
protection).

2.0
Occupational
Handler
Exposure
and
Risk
Summary
2.1
Exposure
Data,
Factors,
and
Assumptions
All
data,
factors,
and
assumptions
used
in
this
addendum
are
the
same
as
those
used
in
the
previous
ORE
assessment.
These
include,
but
are
not
limited
to:


body
weight
(
70
kg
representing
adult
handlers);


toxicological
endpoints
(
short­/
intermediate­
term
oral
NOAEL
of
30
mg/
kg/
day)
and
uncertainty
factors
(
Level
of
Concern
(
LOC)
for
the
MOE
is
100);


application
rates
(
in
lb
ai/
acre
 
presented
as
a
range
to
encompass
the
various
registered
products);
and,


unit
exposures
(
from
PHED
and/
or
ORETF
database,
both
of
which
have
undergone
appropriate
review
by
the
Human
Studies
Review
Board).

The
following
factors,
however,
have
been
revised
based
on
updated
use
pattern
information
and
proposed
product
label
revisions:

 
Application
equipment
Page
3
of
4
Sodium
chlorate
is
applied
to
non­
agricultural
areas
(
i.
e.,
rights­
of­
ways,
building
perimeters,
ditch
banks,
bleachers,
airport
runways,
vacant
lots,
fire
hydrants,
or
as
a
prepaving
treatment)
using
"
handheld"
equipment
such
as
rotary
spreaders
and
pump
or
power
sprayers.
This
is
revised
from
the
previous
assessment
which
assessed
applications
with
larger,
industrial
equipment
such
as
tractor
spreaders
or
groundboom
sprayers.

 
Daily
area
treated
(
i.
e.,
the
area
to
which
an
applicator
applies
per
work
day)

The
previous
assessment
utilized
product
labels
to
establish
the
type
of
equipment
used
to
apply
sodium
chlorate
(
see
"
application
equipment"
above).
Standard
HED
assumptions
for
the
amount
applied
per
work
day
based
on
the
application
equipment
were
used
to
determine
exposure
and
risk.
As
a
result
of
discussions
and
submitted
comments,
however,
it
appears
that
standard
assumptions
would
greatly
overestimate
daily
use
of
sodium
chlorate.
For
example:

o
A
label­
specific
application
of
8
pints
of
product
diluted
in
4
gallons
of
water
applied
to
100
square
feet
[
EPA
Reg.
No.
7701­
34]
yields
a
"
per
acre"
application
rate
of
1032
lbs
sodium
chlorate,
or
2196
gallons
of
solution.
For
typical
applications
in
the
use
sites
described
for
sodium
chlorate,
HED
standard
assumptions
call
for
a
daily
area
treated
for
occupational
settings
of
40
acres
for
larger
industrial
equipment
and
5
acres
for
handheld
rotary
or
power
sprayers.
For
these
amounts,
a
mixer,
loader,
or
applicator
would
have
to
handle
thousands
of
pounds
of
sodium
chlorate
per
day
and
HED
believes
this
to
be
impractical,
if
not
impossible.

The
daily
area
treated
has
therefore
been
revised
to
reflect
the
sodium
chlorate­
specific
use
pattern:

o
Submitted
information
indicates
that
no
more
than
8,000
ft2
of
an
acre
(
approximately
20%)
will
be
treated
with
sodium
chlorate.
Therefore,
HED
has
adjusted
the
standard
assumptions
for
acres
treated
per
day
to
reflect
this
spot
treatment­
type
scenario.
Note:
it
is
recognized
that
this
still
presents
a
conservative
estimate
for
some
scenarios
where
the
adjustment
results
in
treatment
of
1
acre
per
day
which
corresponds
to
the
high
end
estimate
of
1032
lbs
ai
handled
per
day.

2.1
Risk
Summary
Table
1
below
presents
the
revised
risks
for
the
non­
selective
herbicidal
uses
of
sodium
chlorate
in
non­
agricultural/
industrial
areas.

Table
1:
Sodium
Chlorate:
Short­
and
Intermediate­
Term
Occupational
Inhalation
Exposure
Exposure
Scenario
Daily
Area
Treated1
Crop/
Target
Application
Rate2
Inhalation
MOE3
Mitigation
Level4
Mixer/
Loaders
1032
1700
Baseline
523
3300
Baseline
Mixing/
Loading
liquids
for
Rights­
of­
Way
Sprayer
application
1
Industrial/
Non­
Crop
Sites
132
13000
Baseline
Page
4
of
4
Table
1:
Sodium
Chlorate:
Short­
and
Intermediate­
Term
Occupational
Inhalation
Exposure
Exposure
Scenario
Daily
Area
Treated1
Crop/
Target
Application
Rate2
Inhalation
MOE3
Mitigation
Level4
Applicators
1032
520
Baseline
523
1000
Baseline
Rights­
of­
Way
Sprayer
Applications
1
Industrial/
Non­
Crop
Sites
132
4100
Baseline
Mixer/
Loader/
Applicators
&
Loader/
Applicators
1032
170
Baseline
523
330
Baseline
M/
L/
A
liquids
with
a
Low
Pressure
Handwand
Sprayer
0.4
Industrial/
Non­
Crop
Sites
132
1300
Baseline
1032
1100
Baseline
523
2200
Baseline
M/
L/
A
liquids
with
a
Handgun
Sprayer
1
Industrial/
Non­
Crop
Sites
132
8800
Baseline
523
320
Baseline
240
710
Baseline
L/
A
granules
with
a
Belly
Grinder
0.2
Industrial/
Non­
Crop
Sites
161
1100
Baseline
523
550
Baseline
240
1200
Baseline
L/
A
granules
with
a
Push­
type
Spreader
1
Industrial/
Non­
Crop
Sites
161
1800
Baseline
1
Amount
treated
is
presented
in
acres/
day.
Values
are
adjusted
from
Standard
HED
assumptions
(
see
previous
ORE
assessment
 
D307365)
to
reflect
spot
treatment
uses
of
sodium
chlorate
(
i.
e.,
Standard
assumption
*
20%).
2
Ranges
of
application
rates
are
based
on
values
from
label
extractions
(
Appendix
1),
BEAD's
LUIS
reports,
and
the
Sodium
Chlorate
Use
Closure
Memo
(
J.
Guerry,
8/
5/
04;
10/
13/
04;
11/
15/
04).
Application
rates
upon
which
the
analysis
is
based
are
presented
as
lb
ai/
acre.
3
Daily
Inhalation
Dose
(
mg/
kg/
day)
=
[
Application
Rate
(
lb
ai/
A)
*
Daily
Area
Treated
(
A/
day)
*
Unit
Exposure
(
ug/
lb
ai)
*
Inhalation
Abs.
Factor
(
100%)]
/
[
Body
Weight
(
kg)
*
CF
(
1000
ug/
mg)]
Short­/
Int.
Term
Inhalation
MOE
=
Oral
NOAEL
(
30
mg/
kg/
day)
/
Daily
Inhalation
Dose.
HED
LOC
for
MOE
is
100.
4
Mitigation
Levels
Baseline:
No
respirator
