Document ID: EPA-HQ-OPP-2005-0507-0003
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2006-02-01T05:00Z

Page
1
of
8
Summary
of
the
Inorganic
Chlorates
Risk
Assessment
February
1,
2006
Introduction
This
document
summarizes
the
Environmental
Protection
Agency's
(
EPA
or
the
Agency)
human
health
risk
assessment
and
conclusions
for
the
herbicides,
Inorganic
Chlorates
as
presented
fully
in
the
documents,
"
Revised
Inorganic
Chlorates.
HED
Chapter
of
the
Reregistration
Eligibility
Decision
(
RED)
Document"
dated
December
20,
2005,
and
"
Sodium
Chlorate
Ecological
Risk
Assessment"
dated
January
31,
2005.
The
purpose
of
this
summary
is
to
assist
the
reader
by
identifying
the
key
features
and
findings
of
these
risk
assessments,
and
to
allow
the
reader
to
better
understand
the
conclusions
reached
in
the
assessments.
The
human
health
and
ecological
risk
assessments
and
supporting
documents
are
available
for
public
comment
in
EPA's
pesticide
docket
and
on
the
internet.
There
are
some
uncertainties
associated
with
the
assessment
of
risk
to
the
inorganic
chlorates.
Thus
the
Agency
is
requesting
additional
information
from
the
public
so
that
the
most
informed
regulatory
decision
can
be
made.

Of
the
inorganic
chlorates
listed
as
active
ingredients
(
i.
e.,
sodium
chlorate
(
073301),
calcium
chlorate
(
073302),
potassium
chlorate
(
073303),
and
magnesium
chlorate
(
530200),
only
sodium
chlorate
(
073301)
is
present
as
an
active
ingredient
in
currently
registered
products.
Sodium
chlorate
(
873301),
calcium
chlorate
(
875606),
and
potassium
chlorate
(
900583)
are
present
as
inert
ingredients
in
currently
registered
products
and
will
be
briefly
addressed
herein.

Unlike
other
pesticides
for
which
EPA
has
followed
a
cumulative
risk
approach
based
on
a
common
mechanism
of
toxicity,
EPA
has
not
made
a
common
mechanism
of
toxicity
finding
as
to
inorganic
chlorates
and
any
other
substances.
For
information
regarding
EPA's
efforts
to
determine
which
chemicals
have
a
common
mechanism
of
toxicity
and
to
evaluate
the
cumulative
effects
of
such
chemicals,
see
the
policy
statements
released
by
EPA's
Office
of
Pesticide
Programs
concerning
common
mechanism
determinations
and
procedures
for
cumulating
effects
from
substances
found
to
have
a
common
mechanism
on
EPA's
website
at
http://
www.
epa.
gov/
pesticides/
cumulative/.
Page
2
of
8
Use
Profile
Chlorates
are
strong
oxidizers
used
in
the
manufacture
of
dyes,
explosives,
matches,
printing
fabric,
paper
pulp
processing,
weed
killers,
and
as
a
weak
antiseptic,
2­
3%
solutions
have
been
used
in
mouth
washes.
As
a
pesticide,
sodium
chlorate
is
considered
phytotoxic
and
is
used
as
a
defoliant
and
a
desiccant
on
agricultural
crops
to
aid
harvest,
as
well
as
for
spot
treatments
to
control
weeds
on
roadsides
and
residential
properties.
It
is
a
non­
selective,
contact
herbicide
that
can
kill
all
green
parts
of
plants
by
penetrating
the
cuticle
causing
cell
death,
probably
by
altering
the
metabolic
processes.
It
is
used
primarily
in
the
southern
United
States
on
cotton,
but
it
is
also
used
on
a
number
of
other
agricultural
commodities
at
application
rates
that
range
from
approximately
4
to
12.5
lbs
active
ingredient/
acre.
The
primary
use
for
sodium
chlorate
is
as
a
precursor
in
chlorine
dioxide
generation
through
a
closed
system
to
bleach
wood
pulp/
paper.
As
a
defoliant/
desiccant,
professional
agricultural
uses
include:
cotton,
corn,
rice,
dry
beans,
grain
sorghum,
flax,
safflower,
sunflower,
soybeans,
guar
beans,
southern
peas,
chili
peppers
(
for
processing
only),
potatoes,
ornamental
gourds,
cucurbits
(
grown
for
seed),
wheat,
and
fallow
land.
As
a
non­
selective
herbicide
it
is
used
to
kill
grasses
and
weeds
in
industrial
and
non­
crop
sites
such
as:
rights­
of­
way
areas,
building
perimeters,
driveways,
parking
lots,
fence
rows,
tennis
courts,
ditch
banks,
picnic
areas,
bleachers,
cemeteries,
fuel
tank
farms,
airport
runways,
helo
pads,
wood
decks,
guard
rails,
highway
medians,
sidewalks/
walkways,
vacant
lots,
fire
hydrants,
recreational
areas,
pipelines,
railroads,
lumberyards,
and
other
similar
areas.
Only
a
small
percentage
(
less
than
2
percent)
is
used
in
drinking
water
systems
as
a
precursor
to
chlorine
dioxide
generation
or
as
a
defoliant/
desiccant.
As
inert
ingredients,
sodium
chlorate
(
873301)
and
potassium
chlorate
(
900583)
are
present
in
conventional
(
agricultural)
pesticides
used
on
food
crops
or
in
poultry
premises.
Also,
as
inert
ingredients,
sodium
chlorate
(
873301)
and
calcium
chlorate
(
875606)
are
present
in
antimicrobial
agents
used:
(
1)
as
fruit,
vegetable,
and
egg
sanitizing
washes;
(
2)
to
control
bacterial
blotch
on
mushrooms;
(
3)
as
treatment
to
seed
used
for
sprouting;
(
4)
for
conditioning
live
oysters;
(
5)
in
poultry
drinking
water;
(
6)
in
fish
filleting;
and
(
7)
pecan
cracking/
dyeing.

Human
Health
Risk
Assessment
Dietary
Risk
(
Food)

A
chronic
(
non­
cancer
and
cancer)
dietary
risk
assessment
for
food
only
was
conducted
using
the
Dietary
Exposure
Evaluation
Model­
FCID
 
software
with
the
Food
Commodity
Intake
Database
(
DEEM­
FCID
 
Version
2.03)
and
food
consumption
data
from
the
United
States
Department
of
Agriculture's
(
USDA's)
Continuing
Surveys
of
Food
Intakes
by
Individuals
(
CSFII)
from
1994­
1996
and
1998.
The
chronic
(
non­
cancer
and
cancer)
dietary
risk
assessment
for
food
only
is
below
the
Agency's
level
of
concern
for
the
General
U.
S.
Population
and
all
Page
3
of
8
subgroups.
The
highest
exposed
population
subgroup,
children
1­
2
years
of
age,
was
28%
of
the
chronic
Population
Adjusted
Dose
(
cPAD).

Dietary
Risk
(
Drinking
Water)

Chronic
(
non­
cancer
and
cancer)
dietary
(
water
only)
risk
assessments
were
conducted
using
DEEM­
FCID
 
Version
2.03
and
drinking
water
consumption
data
from
the
USDA's
CSFII
from
1994­
1996
and
1998.
Exposures
were
single
point
estimates.

Data
on
the
occurrence
of
chlorate
ion
in
drinking
water
were
available
from
two
primary
sources:
the
Information
Collection
Rule
(
ICR)
Auxiliary
1
Database,
Version
5.0
and
the
AwwaRF
research
study
on
the
control
of
chlorate
ion
in
hypochlorite
solutions.
The
most
extensive
data
is
from
the
ICR
where
source
water
and
drinking
water
were
monitored
for
chlorate
ion
between
July
1997
and
December
1998.
Water
systems
serving
a
population
of
at
least
100,000
were
required
to
monitor
for
chlorate
ion
at
treatment
plants
using
chlorine
dioxide
or
hypochlorite
solutions
in
the
treatment
process.
Plants
using
chlorine
dioxide
collected
monthly
samples
of
the
source
water
entering
the
plant,
the
finished
water
leaving
the
plant,
and
at
three
sample
points
in
the
distribution
system
(
near
the
first
customer,
an
average
residence
time
and
a
maximum
residence
time).
Plants
using
hypochlorite
solutions
were
only
required
to
collect
quarterly
samples
of
the
water
entering
and
leaving
the
plant.
If
chlorine
dioxide
or
hypochlorite
solutions
were
used
intermittently
at
a
plant,
chlorate
ion
samples
were
only
required
in
sample
periods
in
which
they
were
in
use.
The
ICR
Database
was
considered
the
more
appropriate
source
for
estimating
averages
from
individual
water
treatment
plants
primarily
because
the
AwwaRF
study
is
a
less
robust
data
set
consisting
of
only
one
sample
per
utility;
whereas
the
ICR
database
collected
multiple
samples
over
an
18
month
period.
Both
the
AwwaRF
study
and
the
ICR
data
reveal
high
concentrations
of
chlorate
ion
to
be
a
local
problem
affecting
a
relatively
small
number
of
systems.

The
chronic
(
non­
cancer)
dietary
(
water
only)
risk
assessment
for
chlorate
in
drinking
water,
using
the
highest
annual
average
concentration
estimated
at
0.7
mg/
L,
is
below
the
Agency's
level
of
concern
for
the
General
U.
S.
Population
and
all
subgroups
except
all
infants
<
1
year
of
age.
The
highest
exposed
population
subgroup,
all
infants
<
1
year
of
age,
was
161%
of
the
chronic
Population
Adjusted
Dose
(
cPAD).
Using
the
90th
percentile
annual
average
concentration
estimated
at
0.24
mg/
L,
the
chronic
(
non­
cancer)
dietary
(
water
only)
risk
for
all
infants
<
1
year
of
age
was
<
69%
of
the
cPAD
and
23%
of
the
cPAD
using
the
median
annual
average
concentration
estimated
at
0.1
mg/
L.

No
separate
cancer
dietary
risk
assessment
for
chlorate
in
drinking
water
was
conducted.
The
estimated
cancer
dietary
risk
for
the
General
U.
S.
Population
is
based
on
the
chronic
(
noncancer
dietary
risk,
and
is
below
the
Agency's
level
of
concern
i.
e.,
%
cPAD
is
less
than
the
level
of
concern
of
100%.

Use
of
the
ICR
data
could
underestimate
concentrations
in
drinking
water
since
higher
levels
of
chlorate
ion
(
ClO
3
G
)
in
drinking
water
were
found
at
the
smaller
water
treatment
utilities
sampled
in
the
AwwaRF
project
than
at
the
large
water
systems
included
in
the
ICR.
However,
Page
4
of
8
it
should
be
noted
that
although
the
ICR
water
systems
represent
roughly
one
percent
of
the
total
number
of
drinking
water
systems
in
the
United
States,
they
serve
almost
60
percent
of
the
population.
Additionally,
only
four
water
treatment
plants
had
average
chlorate
ion
concentrations
which
exceed
the
Agency's
level
of
concern
(
i.
e.,
370
ppb
or
0.37
mg/
L
for
the
infant
subpopulation)
including
one
treatment
plant
serving
218,000
people
that
had
the
highest
annual
average
(
0.7
mg/
l).
The
total
number
of
people
served
by
the
four
water
treatment
systems
exceeding
0.37
mg/
L
represents
0.5%
of
the
ICR
population
or
621,000
people.
All
three
exposure
ranges
(
highest
average,
90th
percentile,
and
median)
are
presented
in
the
dietary
analysis
(
DEEM).
Only
the
"
highest
average"
exposures
resulted
in
potential
risks
to
infants.
Further,
it
is
estimated
that
less
than
one
percent
of
the
infants
served
by
these
systems
could
be
exposed
to
concentrations
up
to
161%
of
the
chronic
PAD.

Water
systems
that
use
chlorine
dioxide
can
control
the
levels
of
ClO
3
b
in
the
finished
water
through
high
efficiency
operation
of
their
chlorine
dioxide
generators
and
by
reducing
ClO
2
b
concentrations
prior
to
the
addition
of
free
chlorine.
Careful
control
of
the
generation
process
minimizes
chlorate
ion
formation.
Ferrous
ion,
which
is
a
coagulant
aid,
can
be
used
to
convert
ClO
2
b
to
chloride
ion
and
thus
prevent
it
from
reacting
with
free
chlorine
to
form
ClO
3
b
.

Water
system
that
use
hypochlorite
solutions
can
minimize
the
levels
of
chlorate
ion
by
purchasing
high
quality
hypochlorite
solutions
and
through
careful
storage
during
use.
The
pH
of
the
solution
should
be
in
the
12
to
13
range
to
minimize
decomposition.
Hypochlorite
solutions
should
be
protected
from
high
temperatures
and
sunlight.
Storage
time
should
be
minimized;
both
from
the
time
of
manufacture
to
delivery
and
from
the
time
of
delivery
to
use.
The
solutions
can
also
be
diluted
to
control
decomposition
as
long
as
the
proper
pH
is
maintained
and
high
quality
dilution
water
is
used.

It
should
also
be
noted
that
levels
of
chlorate
ion
(
ClO
3
b
)
found
in
finished
drinking
water
are
more
likely
a
consequence
of
drinking
water
treatment
with
chlorine
dioxide
or
hypochlorite
than
from
possible
source
water
contamination
due
to
inorganic
chlorate
pesticide
uses
and/
or
discharge
from
pulp
mills
which
use
inorganic
chlorates
in
their
bleaching
process.
Chlorate
ion
(
ClO
3
b
)
is
a
disinfection
by­
product
(
DBP)
of
water
treatment
which
can
be
formed
during
the
on­
site
generation
of
chlorine
dioxide
(
ClO
2
),
the
decomposition
of
chlorine
dioxide
in
the
water
treatment
system,
the
decomposition
of
hypochlorite
(
OCl
b
)
feedstock
during
storage,
and
the
interaction
of
chlorite
ion
and
free
chlorine.
Chlorate
ion
may
also
be
present
as
a
contaminant
in
the
chlorite
feedstock
material
used
to
generate
chlorine
dioxide
and
in
some
circumstances
may
be
carried
over
to
the
finished
drinking
water.
Technology
to
generate
chlorine
dioxide
using
sodium
chlorate
is
now
available
to
the
drinking
water
industry,
which
introduces
the
possibility
of
ClO
3
­
carryover
to
the
finished
water
from
the
chlorate
feedstock.

Risks
from
Residential
Use
All
residential
(
non­
occupational)
risk
estimates
for
inorganic
chlorates,
as
active
or
inert
ingredients
in
conventional
pesticide
products
used
in
residential
environments,
are
below
the
Agency's
level
of
concern
(
i.
e.,
Margin
of
Exposures
are
greater
than
the
Level
of
Concern
of
100).
These
uses
are
considered
to
be
short­
term
(
1­
30
days)
only
due
to
the
episodic
uses
Page
5
of
8
associated
with
homeowner
products.
It
should
be
noted
that
all
residential
uses
of
the
sodium
chlorate
are
being
voluntarily
canceled
by
the
registrants.

Occupational
Exposure
and
Risk
With
the
addition
of
personal
protection
equipment
(
PPE)
(
dust/
mist
respirator)
or
engineering
controls
(
enclosed
cockpits
or
cabs),
all
occupational
handler
scenarios
for
the
use
of
inorganic
chlorates
as
an
active
or
inert
ingredient
in
conventional
pesticides
are
below
the
Agency's
level
of
concern
(
i.
e.,
Margin
of
Exposures
are
greater
than
the
Level
of
Concern
of
100).
Exposure
durations
are
short­
(
1­
30
days)
and
intermediate­
(
1­
6
months)
term
only.
Since
the
exposure
durations
for
occupational
handlers
are
inconsistent
with
the
mechanism
of
chlorate
carcinogenicity,
an
occupational
cancer
risk
assessment
was
not
conducted.

Postapplication
scenarios
were
not
included
in
the
occupational
risk
assessment
for
inorganic
chlorates.
Although
dermal
and
inhalation
exposures
are
possible,
these
exposures
are
expected
to
be
negligible
due
to
the
physical
and
chemical
characteristics
of
inorganic
chlorates.
Significant
absorption
of
inorganic
chlorates
through
intact
skin
is
not
expected.
Postapplication
inhalation
exposure
is
not
expected
based
on
the
negligible
vapor
pressure
of
sodium
chlorate.

Tolerance
Reassessment
Summary
The
Agency
has
sufficient
information
for
reassessing
the
tolerances
for
preharvest
and
foliar
applications
of
sodium
chlorate
as
a
defoliant
or
desiccant.
Under
40
CFR
180.1020
(
a)
sodium
chlorate
is
exempt
from
the
requirement
of
a
tolerance
for
residues
in
or
on
the
following
raw
agricultural
commodities
when
used
as
a
defoliant,
desiccant,
or
fungicide
in
accordance
with
good
agricultural
practice:
beans
(
dry,
edible),
corn
(
fodder),
corn
(
forage),
corn
(
grain),
cottonseed,
flaxseed,
flax
(
straw),
guar
beans,
peas
(
southern),
peppers
(
chili),
potatoes,
rice,
rice
(
straw),
safflower
(
grain),
sorghum
(
grain),
sorghum
(
fodder),
sorghum
(
forage),
soybeans
and
sunflower
seed.
A
summary
of
the
sodium
chlorate
tolerance
reassessment
and
recommended
modifications
in
commodity
definitions
is
presented
in
Table
1.
Page
6
of
8
Table
1.
Tolerance
Reassessment
Summary
for
Sodium
Chlorate
Listed
under
40
CFR
180.1020(
a)

Commodity
Current
Tolerance
(
ppm)
Tolerance
Reassessment
(
ppm)
[
Correct
Definition]
Comments
beans,
dry,
edible
Exempt
Exempt
[
Bean
(
dry)]

corn,
fodder
Exempt
Exempt
[
Corn]

corn,
forage
Exempt
corn,
grain
Exempt
cottonseed
Exempt
Exempt
[
Cotton]

flaxseed
Exempt
Exempt
[
Flax]

flax,
straw
Exempt
Revoke
Flax
straw
is
not
listed
in
Table
1
of
OPPTS
860.1000
guar
beans
Exempt
Exempt
[
Guar]

peas,
southern
Exempt
Exempt
[
Cowpea]

potatoes
Exempt
Exempt
[
Potato]

peppers,
chili
Exempt
Exempt
[
Pepper
(
nonbell)]

rice
Exempt
Exempt
[
Rice]

rice,
straw
Exempt
Exempt
safflower,
grain
Exempt
Exempt
[
Safflower]

sorghum,
grain
Exempt
Exempt
[
Sorghum
(
grain)]

sorghum,
fodder
Exempt
sorghum,
forage
Exempt
soybeans
Exempt
Exempt
[
Soybeans]

sunflower
seed
Exempt
Exempt
[
Sunflower]

wheat
None
Exempt
[
Wheat]
Concomitant
with
the
revocation
of
wheat
under
40
CFR
180.1020
(
b)
Page
7
of
8
Ecological
Risk
Assessment
Available
data
suggest
that
there
are
no
acute
risk
to
fish,
and
birds,
nor
risks
to
aquatic
plants,
however,
risks
to
fish,
aquatic
invertebrates,
aquatic
plants,
birds,
mammals
and
terrestrial
plants
cannot
be
precluded
due
to
numerous
uncertainties
including
(
1)
uncertainties
in
or
lack
of
toxicity
data;
(
2)
uncertainties
in
the
non­
agricultural
herbicidal
use
pattern;
and
(
3)
uncertainties
in
environmental
chemistry
of
chlorate,
particularly
in
the
amount
of
persistence
of
chemically
related
transformation
products
that
may
form
under
environmental
conditions.
The
registrant
has
recently
submitted
several
ecotoxicity
studies
which
may
significantly
impact
the
ecological
risk
assessment.

Summary
of
Data
Requirements
&
Label
Amendments
Toxicology
870.3465
28­
Day
Inhalation
Study
Residue
Chemistry
860.1480
Magnitude
of
the
Residue
­
Meat,
Milk,
Poultry,
Eggs
860.1650
Submittal
of
Analytical
Reference
Standards
Occupational
and
Residential
Exposure
Sodium
chlorate
(
073301)
end­
use
product
labels
should
be
amended,
as
necessary,
to
include
application
rates
in
terms
of
lbs
a.
i./
acre
treated
for
clarification.

Environmental
Fate
164­
1
Field
dissipation
study
71­
4
Reproduction
toxicity
study
in
bobwhite
quail
and
mallard
ducks.
83­
4
2­
Generation
reproduction
toxicity
study
in
laboratory
rats
72­
4
Chronic
toxicity
studies
in
fish
and
aquatic
invertebrates
123­
1
Tier
II
terrestrial
plant
seedling
emergence
and
vegetative
vigor
studies
123­
2
Tier
II
aquatic
plant
toxicity
studies
Acute
toxicity
studies
in
non­
guideline
fish
and
aquatic
plant
species
Not
all
of
the
current
labels
contain
all
of
the
language
necessary
to
protect
water
resources;
and
should
be
revised
for
consistency.
For
example,
many
labels
do
not
allow
direct
application
to
water
(
surface
water;
intertidal
areas),
use
through
irrigation
systems,
contaminating
water
by
cleaning
of
equipment
or
disposal
of
rinsates,
discharge
into
sewage
systems
without
notifying
the
pertinent
sewage
treatment
plant
authority
(
PTOW),
and
carry
NPDES
license
restriction.
Page
8
of
8
Uncertainties
There
are
some
uncertainties
associated
with
the
assessment
of
risk
to
the
inorganic
chlorates.
So
that
the
Agency
can
make
a
more
informed
regulatory
decision,
the
public
and
other
interested
parties
are
encouraged
to
submit
any
additional
data
to
further
refine
the
risk
assessments,
such
as
worker
exposure
data,
percent
crop
treated
information,
residue
data
from
food
processing
studies,
use
information
for
the
non­
agricultural
uses,
drinking
water
treatment
practices
using
chlorine
dioxide
and
hypochlorite,
etc.,
or
could
address
the
Agency's
risk
assessment
methodologies
and
assumptions
as
applied
to
this
specific
pesticide.