Document ID: EPA-HQ-OPP-2006-0328-0004
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2006-04-26T04:00Z

Chlorine
Dioxide
Occupational
and
Residential
Exposure
Assessment
Case
4023
Timothy
Leighton,
Ph.
D.
Office
of
Pesticide
Programs
Antimicrobials
Division
U.
S.
Environmental
Protection
Agency
1200
Pennsylvania
Avenue,
NW
Washington,
DC
20460
April
5,
2006
Page
2
of
58
TABLE
OF
CONTENTS
1.0
INTRODUCTION......................................................................................................................................
6
1.1
Purpose.................................................................................................................................................
6
1.2
Criteria
for
Conducting
Exposure
Assessments......................................................................................
6
1.3
Chemical
Identification
.........................................................................................................................
6
1.4
Physical/
Chemical
Properties
................................................................................................................
7
2.0
USE
INFORMATION................................................................................................................................
7
2.1
Formulation
Types
and
Percent
Active
Ingredient..................................................................................
7
2.2
Summary
of
Use
Pattern
and
Formulations
............................................................................................
8
3.0
SUMMARY
OF
TOXICITY
CONCERNS
RELATING
TO
EXPOSURES...............................................
15
3.1
Acute
Toxicology................................................................................................................................
15
3.2
Summary
of
Toxicity
Concerns
Relating
to
Exposures.........................................................................
16
3.3
FQPA
Considerations..........................................................................................................................
17
4.0
RESIDENTIAL
AND
PUBLIC
ACCESS
PREMISES
..............................................................................
18
4.1
Summary
of
Registered
Uses...............................................................................................................
18
4.2
Dietary
Exposure/
Risk
Pathway
(
Place
holder)
....................................................................................
18
4.3
Drinking
Water
Exposure/
Risk
Pathway
(
Place
holder)........................................................................
18
4.4
Residential
Exposure/
Risk
Pathway.....................................................................................................
18
4.4.1
Residential
Handler
Exposure........................................................................................................
18
4.4.2
Residential
Post
Application
Exposure...........................................................................................
23
4.4.2.1
Hard
Surface/
Floor
...................................................................................................................
24
4.4.2.2
Ventilation
Systems
..................................................................................................................
30
4.4.2.3
Continuous
Release
(
Gas)
Deodorizer
......................................................................................
31
4.4.2.4
Swimming
Pools
&
Spas...........................................................................................................
33
4.4.3
Data
Limitations/
Uncertainties.......................................................................................................
33
5.0
RESIDENTIAL
AGGREGATE
RISK
ASSESSMENTS
AND
RISK
CHARACTERIZATION
.................
34
6.0
OCCUPATIONAL
EXPOSURE
AND
RISK............................................................................................
34
6.1
Occupational
Handlers
........................................................................................................................
34
6.2
Occupational
Post
Application
Exposure
.............................................................................................
44
6.3
Data
Limitations/
Uncertainties
............................................................................................................
49
7.0
REFERENCES........................................................................................................................................
51
APPENDIX
A:
Summary
of
CMA
data
and
PHED...............................................................................................
53
APPENDIX
B:
Input/
Output
from
E­
FAST/
CEM.................................................................................................
56
Page
3
of
58
EXECUTIVE
SUMMARY
This
document
contains
the
occupational
and
residential
exposure
assessment
for
industrial,
commercial,
residential,
and
agricultural
premises
and
equipment
uses
of
chlorine
dioxide.
Both
sodium
chlorite
and
sodium
chlorate
are
used
as
a
precursor
in
the
generation
of
chlorine
dioxide.
The
handler
exposures
to
sodium
chlorite
are
also
included
in
this
document
because
the
same
toxicological
endpoints
are
used
for
both
chlorine
dioxide
and
sodium
chlorite.
The
handler
exposures
to
sodium
chlorate
itself
are
assessed
in
a
separate
document
(
USEPA,
2005b).

Chlorine
dioxide,
sodium
chlorite,
and
sodium
chlorate
are
active
ingredients
in
numerous
products
used
in
the
control
of
bacteria,
fungi,
and
algal
slimes.
In
addition,
they
are
used
as
material
preservatives
and
as
disinfectants.
At
this
time,
these
products
are
intended
for
agricultural
premises
and
equipment,
commercial,
industrial,
medical
and
residential
use.
The
agricultural
uses
include
the
disinfection
of
hard
surfaces
and
equipment
(
such
as
hatching
facilities
and
mushroom
houses)
and
water
systems
(
such
as
chiller
water
and
humidification
water
in
poultry
houses).
Commercial,
industrial,
and
medical
uses
include
disinfection
of
heating
ventilating
and
air­
conditioning
(
HVAC)
systems,
hard
surfaces
(
e.
g.,
floors,
walls,
and
laboratory
equipment),
water
systems,
pulp/
paper
mills,
and
food
rinses.
Residential
uses
include
disinfection
of
hard
surfaces
(
e.
g.,
floors,
bathrooms),
and
HVAC
systems.
Concentrations
of
chlorine
dioxide
and
sodium
chlorite
in
products
range
from
0.1%
to
80%.
Most
formulations
are
in
liquid
form.
However,
chlorine
dioxide
and
sodium
chlorite
are
also
available
as
tablets,
ready­
to­
use
solutions,
dusts,
and
sachets.
The
application
rates
used
in
this
assessment
were
the
maximum
application
rates
recommended
on
the
product
labels.

Acute
toxicity
categories
for
chlorine
dioxide
include
Category
III
for
oral
and
dermal
and
Category
II
for
inhalation.
The
toxicological
endpoints
selected
to
assess
chlorine
dioxide
and
sodium
chlorite
risks
include
short­
and
intermediate­
term
dermal
and
ingestion
exposure.
The
short­
and
intermediate­
term
NOAEL
for
both
the
dermal
and
oral
routes
is
3
mg/
kg/
day.
For
the
dermal
route,
100
percent
dermal
absorption
is
assumed.
The
oral
NOAEL
is
based
on
depression
of
serum
T4
levels
in
pups
from
dosed
maternal
rats
and
delays
in
development
of
locomotor
and
exploratory
behavior
activities.
For
the
oral
and
dermal
route
of
exposure,
an
uncertainty
factor
or
"
target"
margin
of
exposure
(
MOE)
of
100
is
based
on
10x
for
differences
among
humans
(
intraspecies
variability)
and
10x
for
differences
between
the
test
animals
and
humans
(
interspecies
extrapolation).
Thus,
MOEs
of
greater
than
100
are
above
the
Agency's
target
MOE
for
oral
and
dermal
routes
for
occupational
and
residential
uses.

The
inhalation
route
of
exposure
to
chlorine
dioxide
is
assessed
for
three
distinct
subpopulations:
(
1)
occupational
exposures
(
8
hours/
day,
5
days/
week),
(
2)
one­
time
exposures
for
residential
uses
(
e.
g.,
HVAC
systems,
mopping
floors,
etc),
and
(
3)
long­
term
exposure
for
continuous
release
products
in
the
home
(
24
hours/
day,
7
days/
week).
Several
animal
studies
were
used
to
develop
reference
concentrations
(
RfCs).
The
effects
seen
at
various
concentrations
include
rhinorrhea,
altered
respiration,
respiratory
infection,
bronchial
inflammation,
alveolar
congestion
and
hemorrhage,
vascular
congestion,
and
peribronchiolar
edema.
Readers
are
referred
to
USEPA
(
2005a)
for
a
detailed
review
of
the
effects
seen
at
specific
concentrations
and
exposure
durations
along
with
the
derivation
of
the
RfC.
In
summary,
the
occupational
RfC
Page
4
of
58
is
determined
to
be
0.003
ppm
and
represents
an
8­
hour
time
weighted
average
(
TWA).
The
one­
time
residential
exposure
scenario
is
represented
by
the
RfC
of
0.05
ppm
and
the
RfC
for
long­
term,
continuous
exposure
is
0.00007
ppm.
The
RfC
methodology
incorporates
the
uncertainty
factors
into
the
concentration.
For
inhalation,
the
RfC
is
compared
directly
to
the
air
concentration
of
interest.
Inhalation
risks
are
of
concern
if
the
air
concentrations
people
are
exposed
to
exceed
the
RfC.

The
exposure
scenarios
selected
as
representative
uses
of
chlorine
dioxide
to
be
assessed
in
the
risk
assessment
are
presented
in
the
table
at
the
end
of
this
section.
These
scenarios
were
based
on
examination
of
product
labels
describing
uses
for
the
product.
Several
different
sources
of
handler
exposure
data
were
used
to
assess
occupational
and
residential
chlorine
dioxide
risks.
Data
from
both
the
proprietary
Chemical
Manufacturers
Association
(
CMA)
antimicrobial
exposure
study
and
the
Pesticide
Handlers
Exposure
Database
(
PHED)
were
used.
In
addition,
chemical­
specific
data
were
available
to
assess
inhalation
exposures
for
the
following
uses:
HVAC,
carpet,
automobiles,
and
OSHA's
Integrated
Management
Information
System
(
IMIS)
for
various
industrial
uses.

Residential
Risks
For
residential
dermal
exposures,
the
calculated
MOEs
for
handlers
are
less
then
the
target
MOE
of
100
for
the
swimming
pool
&
spa
application
scenarios
(
i.
e.,
for
placing
tablets
into
swimming
pools/
spas,
the
dermal
MOE
=
46).
Note:
The
risk
may
be
over
stated
because
the
dermal
absorption
was
assumed
to
be
100
percent
due
to
the
lack
of
a
dermal
absorption
study
or
dermal
route­
specific
toxicity
study.
If
the
applicator
wears
gloves,
the
dermal
risk
would
be
mitigated
(
i.
e.
MOE
is
500)
The
inhalation
exposures
to
the
handlers
are
not
of
concern.

The
calculated
dermal
and
incidental
oral
MOEs
for
post
application
exposure
were
not
of
concern
for
all
scenarios.
The
post
application
inhalation
MOEs
were
not
of
concern
except
for
dust
applications
to
carpets.
Although
the
inhalation
risks
were
indeterminate
for
the
carpet
use,
additional
monitoring
data
are
warranted
based
on
the
air
concentration
measurements
available
3
to
4
hours
post
treatment.

One
product
has
been
identified
that
is
registered
as
a
continuous
release
of
chlorine
dioxide
gas
in
homes.
The
product
is
packaged
as
a
pouch
or
sachet.
A
bounding
estimate
of
air
concentration
is
presented
based
on
the
application
rate
and
the
label­
referenced
longevity
of
the
pouches/
sachets.
The
theoretical
constant
air
concentration
would
be
0.52
ppm
assuming
no
air
exchange
and
no
build
up
of
chlorine
dioxide
over
time
because
of
the
short
half­
life.
The
RfC
for
long­
term
continuous
exposure
is
0.00007
ppm.
Therefore,
the
theoretical
concentration
from
the
product's
release
is
of
concern.
Before
any
refinements
to
these
air
concentration
estimates
are
attempted,
it
should
be
determined
if
the
product's
efficacy
can
be
maintained
at
the
RfC
of
~
0.00007
ppm.

Occupational
Risks
For
occupational
dermal
exposures,
calculated
MOEs
less
than
the
target
dermal
MOE
of
Page
5
of
58
100
were
found
for
the
following
handler
scenarios:
Agricultural
Premises
and
Equipment
°
application
to
hard
surfaces
via
low­
pressure
hand
wand
(
MOE
=
31)
°
application
to
hard
surfaces
via
mopping
(
MOE
=
70)
°
foam
applicator
to
animal
transport
vehicles/
tractor
trailer
(
MOE
=
8)

Food
Handling,
Commercial/
Institutional,
and
Medical
Premises
and
Equipment
°
application
to
hard
surfaces
via
mopping
(
MOE
=
66
for
commercial
and
3
for
medical)

Inhalation
exposures/
risks
were
not
assessed
separately
for
the
handlers.
Instead,
the
occupational
inhalation
handler
exposures
are
combined
as
part
of
the
full
work
day
for
handler/
bystanders
to
be
comparable
to
EPA's
inhalation
toxicological
endpoint
which
is
based
on
an
8­
hour
TWA.
For
the
peak,
short­
term
exposures
to
chlorine
dioxide
gas
experienced
during
mixing/
loading
and/
or
system
leaks/
failures,
EPA
will
rely
on
the
American
Conference
of
Governmental
Industrial
Hygienists
(
ACGIH)
Short­
term
Exposure
Limit
(
STEL)
and
Immediately
Dangerous
to
Life
or
health
(
IDLH)
to
mitigate
risks.

For
most
of
the
bystander/
post
application
occupational
scenarios,
dermal
exposures
are
not
expected
to
occur
or
are
expected
to
be
negligible
based
on
the
relatively
low
application
rates
and
chemical
properties
(
e.
g.,
volatility
and
short
½
life)
of
chlorine
dioxide,
sodium
chlorite
and
sodium
chlorate.
However,
the
inhalation
risks
for
the
bystander/
post
application
occupational
exposures
are
of
concern
using
the
EPA's
selected
inhalation
toxicological
endpoint
(
RfC).
The
occupational
RfC,
0.003
ppm,
is
below
the
limit
of
detection
for
chlorine
dioxide.
Based
on
OSHA's
IMIS
data
available
for
chlorine
dioxide,
all
air
concentration
measurements,
even
those
that
were
nondetect,
are
above
the
RfC.
Reconciliation
of
the
EPA
risk­
based
RfC
and
current
OSHA
standards
will
be
made
during
the
regulatory
decision
phase
of
the
Reregistration
Eligibility
Decision
(
RED)
for
chlorine
dioxide.

There
are
a
number
of
uncertainties
associated
with
this
assessment
(
see
Sections
4.4.3
and
6.3).
In
general,
conservative
values
were
used
in
cases
where
data
were
lacking.
Assessments
for
these
scenarios
should
be
considered
as
screening­
level.

Use
Scenarios
Based
on
Product
Labels
for
Chlorine
Dioxide,
Sodium
Chlorite
and
Sodium
Chlorate
Use
Site
Scenario
Agricultural
Premises
and
Equipment
Low
pressure
hand
wand,
fog,
mop,
spray,
foaming
wand
for
hard
surfaces
Fogging
(
e.
g.,
egg
houses)
Food
Handling,
Commercial/
Institutional,
Medical
Mop
and
spray
on
hard
surfaces
Fruit
&
vegetable
dip
Residential
and
Public
Access
Trigger­
pump
sprayer
and
mop
to
hard
surfaces
HVAC
reentry
Solid
tablets
for
swimming
pools
and
spas
Continuous
release
deodorizer
Page
6
of
58
Use
Scenarios
Based
on
Product
Labels
for
Chlorine
Dioxide,
Sodium
Chlorite
and
Sodium
Chlorate
Use
Site
Scenario
Human
Drinking
Water
Systems
Metering
pump
for
potable
water
and
storage
systems
Material
Preservatives
Metal
working
fluids
(
MWF)

Industrial
Processes
and
Water
Systems
Metering
pump
to
pulp
and
paper
white
water
systems
Liquid
pour
to
oil
systems
Swimming
Pools
and
Aquatic
Areas
Liquid
pour
to
non­
potable
water
systems
(
e.
g.,
retention
ponds
and
decorative
fountains)

Tablets
in
the
circulation
systems
of
swimming
pools
&
spas
HVAC
Systems
Spray
and
fog
of
ventilation
systems
(
e.
g.,
duct
work)

1.0
INTRODUCTION
1.1
Purpose
In
this
document,
EPA
presents
the
results
of
its
review
of
the
potential
human
health
effects
of
occupational
and
residential
exposure
to
chlorine
dioxide,
including
the
releases
of
chlorine
dioxide
from
sodium
chlorite
and
sodium
chlorate
applications.
This
information
is
for
use
in
EPA's
development
of
the
chlorine
dioxide
Reregistration
Eligibility
Decision
(
RED)
document.

1.2
Criteria
for
Conducting
Exposure
Assessments
An
occupational
exposure
assessment
is
required
for
an
active
ingredient
if
(
1)
certain
toxicological
criteria
are
triggered
and
(
2)
there
is
potential
exposure
to
handlers
(
mixers,
loaders,
applicators,
etc.)
during
use
or
to
persons
entering
treated
sites
after
application
is
complete.
For
chlorine
dioxide,
both
criterions
are
met.
Note:
The
toxicity
of
sodium
chlorite
has
been
assumed
to
be
equivalent
to
that
of
chlorine
dioxide.

1.3
Chemical
Identification
Three
chemicals
are
considered
in
this
document:
chlorine
dioxide,
sodium
chlorite,
and
sodium
chlorate.
Products
containing
chlorine
dioxide
or
sodium
chlorite
have
been
included
in
this
risk
assessment.
Risks/
exposures
to
sodium
chlorate
itself
have
been
assessed
in
a
separate
document:
"
Sodium
Chlorate:
Occupational
and
Residential
Exposure
Assessment
of
Antimicrobial
Uses
for
the
Reregistration
Eligibility
Decision
Document"
(
USEPA,
2005).
However,
risks
to
chlorine
dioxide
released
from
sodium
chlorate
applications
are
included
in
the
scope
of
this
document.
Table
1.1
presents
the
chemical
identification
information
for
the
three
chemicals.
Page
7
of
58
Table
1.1.
Chemical
Identification
Information
for
Chlorine
Dioxide,
Sodium
Chlorite,
and
Sodium
Chlorate
Chlorine
Dioxide
Sodium
Chlorite
Sodium
Chlorate
OPP
Chemical
Code
020503
020502
073301
CAS
Number
10049­
04­
4
7758­
19­
2
7775­
09­
9
Molecular
Formula
ClO2
NaClO2
NaClO3
1.4
Physical/
Chemical
Properties
Table
1.2
shows
physical/
chemical
characteristics
that
have
been
reported
for
chlorine
dioxide
and
sodium
chlorite.

Table
1.2.
Physical/
Chemical
Properties
of
Chlorine
Dioxide
and
Sodium
Chlorite
Property
Chlorine
Dioxide
Sodium
Chlorite
Molecular
Weight
67.45
g/
mol
90.45
g/
mol
Color
Yellow
to
Reddish
Yellow
White
Melting
Point
­
59oC
180­
200oC
(
decomposes)

Boiling
Point
11oC
n/
a
Odor
Strongly
pungent,
chlorine­
like
n/
a
Physical
State
Gas
at
room
temperature
Solid
Density
1.64
g/
ml
at
0oC
(
liquid)
1.614
g/
ml
at
10o
C
(
liquid)
2.468
g/
ml
(
as
a
solid)

Vapor
Pressure
490
mm
Hg
(
0oC)
>
760
mm
Hg
(
25oC)
n/
a
Stability
Unstable,
estimated
half
life
in
water
~
25
minutes
n/
a
Solubility
(
water)
3.01
g/
L
at
25oC
and
34.5
mmHg
390
g/
L
at
30oC
References:
ATSDR
2004
and
Gates
1998
2.0
USE
INFORMATION
2.1
Formulation
Types
and
Percent
Active
Ingredient
Concentrations
of
chlorine
dioxide
and
sodium
chlorite
in
products
range
from
0.1%
to
80%.
Most
formulations
are
in
liquid
form.
However,
chlorine
dioxide
and
sodium
chlorite
are
also
available
as
tablets,
wettable
powders,
and
water­
soluble
packets.
Registered
uses
include
use
as
a
fruit/
vegetable
rinse,
potable
water
treatment,
hard
surface
disinfectant,
disinfectant
of
ventilation
systems,
foggers,
material
preservatives
(
e.
g.,
water
based
cutting
oils),
industrial
systems
(
e.
g.,
water
cooling
towers),
and
non­
potable
water
systems.
Page
8
of
58
2.2
Summary
of
Use
Pattern
and
Formulations
Chlorine
dioxide
and
sodium
chlorite
are
active
ingredients
in
numerous
products
used
in
the
control
of
bacteria,
fungi,
and
algal
slimes.
In
addition,
chlorine
dioxide
and
sodium
chlorite
are
used
as
material
preservatives
and
as
disinfectants.
At
this
time,
products
containing
chlorine
dioxide
and
sodium
chlorite
are
intended
for
agricultural,
commercial,
industrial,
medical,
and
residential
use.
The
agricultural
uses
include
the
disinfection
of
hard
surfaces
and
equipment
(
such
as
hatching
facilities
and
mushroom
houses)
and
water
systems
(
such
as
chiller
water
and
humidification
water
in
poultry
houses).
Commercial,
industrial,
and
medical
uses
include
disinfection
of
ventilation
systems,
hard
surfaces
(
e.
g.,
floors,
walls,
and
laboratory
equipment),
water
systems,
pulp/
paper
mills,
and
food
rinses.
Residential
uses
include
disinfection
of
hard
surfaces
(
e.
g.,
floors,
bathrooms),
and
ventilation
systems
along
with
a
pool/
spa
water
circulation
system
treatment.

The
Agency
determines
potential
exposures
to
handlers
of
the
product
by
considering
exposure
scenarios
from
the
various
application
methods
that
are
plausible,
given
the
label
uses.
Based
on
review
of
the
product
labels
and
the
various
uses
identified,
several
potential
exposure
scenarios
were
chosen
for
this
risk
assessment.
Those
scenarios,
the
methods
of
application,
and
the
maximum
application
rates
are
provided
in
Tables
2.1
through
2.3.
Tables
of
use
scenarios
are
provided
for
chlorine
dioxide,
sodium
chlorite,
and
sodium
chlorate.
Representative
uses
were
chosen
from
all
of
the
uses
for
all
three
chemicals,
based
on
application
method,
rate
and
potential
exposures.
After
review
of
the
labels,
it
was
determined
that
sodium
chlorite
and
chlorine
dioxide
labels
represent
the
highest
application
rates
that
produce
chlorine
dioxide.
Application
rates
were
determined
in
pounds
active
ingredient
per
gallon
(
lb
ai/
gal).
It
is
assumed
that
rates
of
sodium
chlorite
produce
equivalent
rates
of
chlorine
dioxide
(
e.
g.,
0.08
lb
ai/
gal
of
sodium
chlorite
solution
equals
0.08
lb
ai/
gal
of
chlorine
dioxide).
The
density
of
chlorine
dioxide
in
liquid
form
(
1.642
g/
cm3
or
13.7
lb/
gal)
was
used
to
determine
the
lbs
ai/
gal.
It
was
assumed
that
a
100%
active
ingredient
solution
would
contain
13.7
lb
ai/
gal.
This
ratio
was
then
used
to
determine
the
lb
ai/
gal
for
other
products,
by
multiplying
the
%
ai
provided
on
the
label
by
a
factor
of
0.137
(
13.7/
100).
For
some
of
the
sodium
chlorite
labels,
the
application
rate
was
not
provided
in
terms
of
lbs
ai/
gal.
Therefore,
a
ratio
of
lbs
ai/
gal
to
%
ai
was
used
from
another
label
(
0.1032;
EPA
Reg.
1757­
96).
This
ratio
was
multiplied
by
the
%
ai
to
estimate
the
lbs
ai/
gal.
Page
9
of
58
Table
2.1.
Use
Scenarios
and
Methods
of
Application
Based
on
Product
Labels
for
Chlorine
Dioxide
Uses
Representative
Exposure
EPA
Reg.
#
Associated
with
Maximum
Exposure
Application
Rate
Associated
with
Maximum
Exposure
(
lb
a.
i./
gallon)
Residual
Chlorine
Dioxide
Level
(
ppm)

Use
Site
Category
I
(
Agricultural
Premises
and
Equipment)
a
$
Low­
pressure
hand
wand
0.014
1000
$
fog
(
1
hour
REIb)
0.014
1000
$
mop
$
spray
0.018
1250
$
dip
(
e.
g.,
litter
boxes)
Liquid
concentrate
9150­
2
0.014
1000
$
shampoo
Liquid
concentrate
9804­
1
0.008
500
Application
to
hard
surfaces
(
e.
g.,
animal
rearing
and
confinement
facilities;
horticulture
uses;
mushroom
facilities)

$
foaming
wand
(
animal
transport
vehicles;
agricultural
storage
facilities;
containers,
trailers,
rail
cars,
vessels)
Liquid
concentrate
9150­
11
0.025
not
provided
chiller
water
$
liquid
pour
Liquid
concentrate
9150­
2
0.001
40
Water
systems
humidification
water
in
poultry
houses
$
mist
or
fog
(
1
hour
REI)
Liquid
concentrate
9150­
2
0.001
40
Use
Site
Categories
II
(
Food
Handling),
III
(
Commercial/
Institutional),
and
V
(
Medical)

Application
to
hard
surfaces
with
food
contact
in
Food
processing
plants;
Hospitals
(
e.
g.,
water
bath
incubators,
autoclaves);
Public
places
(
e.
g.,
restaurants,
hotel/
motel
rooms);
Medical/
Dental
offices
$
spray
9150­
2
Liquid
Concentrate
0.014
1000
Page
10
of
58
Table
2.1.
Use
Scenarios
and
Methods
of
Application
Based
on
Product
Labels
for
Chlorine
Dioxide
Uses
Representative
Exposure
EPA
Reg.
#
Associated
with
Maximum
Exposure
Application
Rate
Associated
with
Maximum
Exposure
(
lb
a.
i./
gallon)
Residual
Chlorine
Dioxide
Level
(
ppm)

Application
to
hard
surfaces
without
food
contact
in
Food
processing
plants;
Hospitals
(
e.
g.,
water
bath
incubators,
autoclaves);
Public
places
(
e.
g.,
restaurants,
hotel/
motel
rooms);
Medical/
Dental
offices
$
mop
or
spray
9150­
10
active
Liquid
concentrate
(
10589­
3
transferred)
0.019
not
provided
Canner
retort
and
pasteurizer
cooling
water
$
liquid
pour;
chemical
feed
pump
or
injector
9804­
1
Liquid
concentrate
0.00007
5
Humidification
water
on
stored
potatoes
$
mist
or
fog
(
1
hour
REI
after
fogging)
9804­
5
Liquid
concentrate
0.003
200
Water
systems
Potable
water,
ice
made
from
potable
water
$
liquid
pour
9804­
5
Liquid
concentrate
0.017
not
provided
Ventilation
systems
(
HVAC)
Ventilation
systems
(
HVAC)

$
spray
or
fog
(
1hour
REI
after
fogging)
9804­
1
Liquid
concentrate
0.007
500
Fruit/
Vegetable
rinses
$
dip
Liquid
concentrate
9150­
2
0.002
not
provided
Use
Site
Category
IV
(
Residential
&
Public
Access)
Application
to
hard
surfaces
(
e.
g.,
floors,
carpet,
bedding,
furniture)
$
Pump­
trigger
9804­
3
Liquid
concentrate
0.002
not
provided
Evaporative
cooler
$
liquid
pour
9150­
11
Liquid
concentrate
0.0007
not
provided
Ventilation
systems
(
HVAC)
$
Handler
not
assessed,
only
post
application
(
1
hour
REI
after
fogging)
9804­
1
Liquid
concentrate
0.007
500
ppm
Decorative
pools,
fountains,
and
water
displays
$
liquid
pour
9150­
11
Liquid
concentrate
0.0001
not
provided
Continuous
release
deodorizer
Handler
not
assessed,
only
post
application
inhalation
70060­
12
Pouch/
Sachet
NA
not
provided
Use
Site
Category
VI
(
Human
Drinking
Water
Systems)
Water
Treatment
and
water
storage
systems
$
liquid
pour
and/
or
metering
pump
9804­
1
Liquid
concentrate
0.008
(
to
treat
water
storage
system
of
aircraft,
boats,
RVs,
offshore
oil
rigs)
500
Page
11
of
58
Table
2.1.
Use
Scenarios
and
Methods
of
Application
Based
on
Product
Labels
for
Chlorine
Dioxide
Uses
Representative
Exposure
EPA
Reg.
#
Associated
with
Maximum
Exposure
Application
Rate
Associated
with
Maximum
Exposure
(
lb
a.
i./
gallon)
Residual
Chlorine
Dioxide
Level
(
ppm)

0.00007
(
to
treat
stored
potable
water)
5
Use
Site
Category
VII
(
Material
Preservatives)
Industrial
application
to
water
based
cutting
oils
(
MWF)
$
liquid
pour
and/
or
metering
pump
9150­
2
Liquid
concentrate
(
5%
ai
assume
density
8
lb/
gal)
batch
method:
0.0001
(
per
week)

continuous
method:
8E­
7
(
per
day)

badly
contaminated
systems:
4E­
6
(
slug
dose)
not
provided
Use
Site
Category
VIII
(
Industrial
Processes
and
Water
Systems)
Application
to
hard
surfaces
(
e.
g.,
evaporative
cooler)
$
liquid
pour
and/
or
metering
pump
9150­
11
Liquid
concentrate
0.0007
not
provided
Water
filtration
systems,
sand
beds,
gravel
beds,
charcoal
filters
(
e.
g.,
to
control
mollusks)
$
liquid
pour
and/
or
metering
pump
9150­
2
Liquid
concentrate
0.03
2000
9150­
2
Liquid
concentrate
3.1
lb
ai/
100
tons
paper
produced
not
provided
Paper
mill
systems
$
liquid
pour
and/
or
metering
pump
9804­
1
Liquid
concentrate
0.00007
5
Oil
wells
$
liquid
pour
and/
or
metering
pump
9150­
2
Liquid
concentrate
0.069
5000
Use
Site
Categories
XI
and
XII
(
Swimming
Pools
and
Aquatic
Areas)

Non­
potable
water
systems
(
e.
g.,
retention
basins
and
ponds,
decorative
pools
and
fountains)
$
liquid
pour
and/
or
metering
pump
9150­
11
Liquid
concentrate
0.00001
(
18
fl
oz
x
0.72%
ai
per
100
gallons
water)
10
Use
Site
Category
XIII
(
HVAC)
Ventilation
systems
$
spray
or
fog
(
1hour
REI
after
fogging)
9804­
1
Liquid
concentrate
0.007
500
a
Applications
are
made
in
agricultural
settings
including,
but
not
limited
to,
mushroom
houses,
poultry
facilities,
animal
facilities,
and
hatching
facilities.
b
REI
=
Reentry
Interval
Page
12
of
58
Table
2.2.
Use
Scenarios
and
Methods
of
Application
Based
on
Product
Labels
for
Sodium
Chlorite
Uses
Representative
Exposure
EPA
Reg.
#
Associated
with
Maximum
Exposure
Application
Rate
Associated
with
Maximum
Exposure
(
lb
a.
i./
gallon)
Residual
Chlorine
Dioxide
Level
(
ppm)

Use
Site
Category
I
(
Agricultural
Premises
and
Equipment)
a
$
low­
pressure
hand
wand
74602­
02
Liquid
concentrate
70060­
18
tablet
0.015
0.002
1000
100
$
high
pressure
hand
wand
74602­
02
Liquid
concentrate
0.0003
20
$
spray
or
fog
(
1
hour
REI
after
fogging)
74602­
02
Liquid
concentrate
0.0083
500
Application
to
hard
surfaces
(
e.
g.,
Animal
rearing
and
confinement
facilities;
Horticulture
uses;
Mushroom
facilities)

$
shampoo
74602­
02
Liquid
concentrate
0.008
500
Water
supply
(
e.
g.,
drinking
water,
humidification
water
in
poultry
houses)
$
liquid
pour
74602­
02
Liquid
concentrate
°
.0006
40
Use
Site
Categories
II
(
Food
Handling),
III
(
Commercial/
Institutional),
and
V
(
Medical)

$
foam
21164­
8
Liquid
concentrate
0.002
Not
provided
Application
to
hard
surfaces
with
food
contact
in
Food
processing
plants;
Hospitals
(
e.
g.,
water
bath
incubators,
autoclaves);
Public
places
(
e.
g.,
restaurants,
hotel/
motel
rooms);
Medical/
Dental
offices
$
spray
or
dip
74602­
02
Liquid
concentrate
0.003
200
$
spray
$
mop
$
sponge
$
immersion
70060­
19
tablet
0.005
200
$
sprayer
or
dilution
device
74986­
1
WP
100
$
spray
$
mist
$
sponge
21164­
3
Liquid
concentrate
0.08
Not
provided
$
fog/
mist
(
15
min
REI)
21164­
3
Liquid
concentrate
0.007
Not
provided
$
RTU
packet
70060­
12
RTU
packet
**
Not
provided
Application
to
hard
surfaces
without
food
contact
in
Food
processing
plants;
Hospitals
(
e.
g.,
water
bath
incubators,
autoclaves);
Public
places
(
e.
g.,
restaurants,
hotel/
motel
rooms);
Medical/
Dental
offices
(
cont.)

$
RTU
packet
70060­
13
RTU
packet
0.04
lb
ai
(
20
lb
ai/
day)
Not
provided
Water
systems
(
e.
g.,
potable
water)
$
liquid
pour
9150­
7
Liquid
concentrate
0.002
150
Page
13
of
58
Table
2.2.
Use
Scenarios
and
Methods
of
Application
Based
on
Product
Labels
for
Sodium
Chlorite
Uses
Representative
Exposure
EPA
Reg.
#
Associated
with
Maximum
Exposure
Application
Rate
Associated
with
Maximum
Exposure
(
lb
a.
i./
gallon)
Residual
Chlorine
Dioxide
Level
(
ppm)
70060­
16
tablet
0.000004
Not
provided
Fruit/
vegetable
rinse
$
dip
74602­
02
Liquid
concentrate
0.011
1200
Air
Deodorizer
$
fog
(
15
min
REI)
74602­
3
Liquid
concentrate
0.007
Not
provided
Carpet
deodorizer
$
duster
70060­
4
Dust
0.0001
lb
ai/
ft2
Not
provided
Use
Site
Category
IV
(
Residential
&
Public
Access)

Application
to
hard
surfaces
(
e.
g.,
bathrooms,
laundry
rooms,
trash
cans)
$
RTU
packet
70060­
12
RTU
packet
**
Not
provided
Room/
Surface
deodorizer
$
spray,
sponge
74602­
02
Liquid
concentrate
0.004
Not
provided
Carpet
deodorizer
$
duster
70060­
4
Dust
0.0001
lb
ai/
ft2
Not
provided
Residential
and
Industrial
Ion
Exchange
Resin
Beds
$
tablet
70060­
19
tablet
0.003
lb
ai/
ft3
Not
provided
Use
Site
Category
VI
(
Human
Drinking
Water
Systems)

$
sprayer
or
dilution
device
74986­
1
(
potable
water
systems)
WP
Not
provided
100
5382­
46
(
potable
water
systems)
Liquid
concentrate
0.00008
5
$
liquid
pour
and/
or
metering
pump
74602­
02
(
aircraft,
boats,
RVs,
offshore
oil
rigs)
Liquid
concentrate
0.008
500
Water
Treatment
and
water
storage
systems
$
tablet
70060­
22
(
emergency
disinfection
of
drinking
water)
tablet
0.0002
Not
provided
Use
Site
Category
VII
(
Material
Preservatives)

Pulp/
Paper
products
Polymers
Emulsions
Adhesives
Pigment
slurries
$
liquid
pour
and/
or
metering
pump
74655­
2
Liquid
concentrate
Not
provided
1000
Use
Site
Category
VIII
(
Industrial
Processes
and
Water
Systems)

Water
cooling
systems
(
e.
g.,
commercial
and
industrial
$
tablet
70060­
16
tablet
0.000004
Not
provided
Page
14
of
58
Table
2.2.
Use
Scenarios
and
Methods
of
Application
Based
on
Product
Labels
for
Sodium
Chlorite
Uses
Representative
Exposure
EPA
Reg.
#
Associated
with
Maximum
Exposure
Application
Rate
Associated
with
Maximum
Exposure
(
lb
a.
i./
gallon)
Residual
Chlorine
Dioxide
Level
(
ppm)
recirculation
cooling
water
systems,
once
through
cooling
water
systems)
$
water
soluble
packet
72874­
1
WSP
(
bag)
0.0002
Not
provided
Recycle
wash
water
systems
$

tabletcanister
feed
or
tank
addition
70060­
16
tablet
0.00009
Not
provided
Oil
field
secondary
recovery
operations
$
liquid
pour
and/
or
metering
pump
21164­
3
Liquid
concentrate
0.007
Not
provided
Paper
mills
$
liquid
pou
and/
or
metering
pump
74602­
3
Liquid
concentrate
0.0001
lb
ai/
gal
white
water
(
3.44
lb
ai/
100
ton
paper
produced)
Not
provided
Use
Site
Category
XI
(
Swimming
Pools)

Swimming
pools
&
Spas
(
place
2
tablets
in
skimmer
and
2
tablets
in
hair/
lint
basket
to
clean
pool
circulation
system)
$
tablet
70060­
20
tablet
4
tablet
/
10,000
gal
(
Pool
tablet
is
100
g
x
4
tablets
x
20%
ai
=
80
g
ai/
10,000
gal
=
1.8E­
5
lb
ai/
gal)
Not
provided
Use
Site
Category
XII
(
Aquatic
Areas)

$
liquid
pour
and/
or
metering
pump
53345­
23
Liquid
concentrate
Not
provided
2
Water
Treatment
and
water
storage
systems
(
e.
g.,
municipal
water,
nonpotable
water
used
with
cut
flowers)
$
sprayer
or
dilution
device
74986­
1
WP
Not
provided
100
**
Label
lists
various
application
rates:
refrigerator:
0.006
lb
ai;
shoes:
0.0006
lb
ai;
hamper:
0.01
lb
ai/
ft2;
basement:
0.0002
lb
ai/
ft2;
gym
locker:
0.0002
lb
ai/
ft3;
cars:
0.006
lb
ai;
boats:
0.0002
lb
ai/
ft3;
athletic
bag:
0.0003
lb
ai/
ft3;
trash
can:
0.006
lb
ai;
trash
bag:
0.006
lb
ai;
diaper
pail:
0.002
lb
ai;
litter
box/
pet
area:
0.0001
lb
ai
Page
15
of
58
Table
2.3.
Use
Scenarios
and
Methods
of
Application
Based
on
Product
Labels
for
Sodium
Chloratea
Uses
Representative
Exposure
EPA
Reg.
#
Associated
with
Maximum
Exposure
Application
Rate
Associated
with
Maximum
Exposure
(
lb
a.
i./
gallon)
Residual
Chlorine
Dioxide
Level
(
ppm)

Use
Site
Categories
I
(
Agricultural),
II
(
Food
Handling),
III
(
Commercial/
Institutional),
VIII
(
Industrial
Processes
and
water
systems),
XII
(
Aquatic
areas)
Agricultural
water
uses
49620­
4
­­
a
2
Pasteurizer./
Cannery/
Retort
49620­
4
­­
a
0.4
Cooling
towers;
wastewater
10707­
32
­­
a
800
Pulp
and
Paper
53345­
17/­
18
­­
a
4000
Gas/
oil
injection
49620­
4
­­
a
3000
Water
systems
Ultrasonic
tank
water
and
photo
processing
was
water
49620­
4
­­
a
5
Aquatic
areas
(
e.
g.,
lakes
and
reservoirs)
49650­
4
­­
a
5
a
Table
developed
from
Table
2
of
the
Sodium
Chlorate
ORE
Document;
application
rates
were
not
provided
3.0
SUMMARY
OF
TOXICITY
CONCERNS
RELATING
TO
EXPOSURES
3.1
Acute
Toxicology
Chlorine
dioxide
(
CAS
No.
10049­
04­
4)
is
used
as
a
disinfectant
in
a
variety
of
sites,
including
drinking
water,
swimming
pools,
fruits
and
vegetables,
and
household
uses.
Sodium
chlorite
and
sodium
chlorate
products
release
chlorine
dioxide
and
are
included
in
this
assessment
as
well.

Table
3.1
presents
the
acute
toxicity
categories
as
outlined
in
the
toxicity
memorandum
dated
February
15,
2005
(
USEPA,
2005a).

Table
3.1.
Acute
Toxicity
Categories
for
Chlorine
Dioxide
Study
Type
Toxicity
Categorya
Acute
Oral
Toxicity
II
Acute
Dermal
Toxicity
III
Acute
Inhalation
Toxicity
II
Primary
Eye
Irritation
III
Primary
Dermal
Irritation
II
Dermal
Sensitization
No
acceptable
sensitization
study
available
a
The
available
acute
studies
are
all
graded
as
acceptable.
An
acceptable
dermal
sensitization
study
is
not
available
in
the
database.
Page
16
of
58
3.2
Summary
of
Toxicity
Concerns
Relating
to
Exposures
Chlorine
Dioxide/
Sodium
Chlorite
­
Report
of
the
Hazard
Identification
Assessment
Review
Committee
and
the
Antimicrobials
Division
Toxicity
Endpoint
Selection
Committee
(
USEPA
2005a)
indicates
that
there
are
toxicological
endpoints
of
concern
for
chlorine
dioxide.
The
endpoints
and
associated
uncertainty
factors
used
in
assessing
the
risks
for
chlorine
dioxide
are
presented
in
Table
3.2.
These
endpoints
have
also
been
identified
for
sodium
chlorite.
Since
the
same
endpoints
have
been
identified
for
both
chemicals,
this
risk
assessment
examines
products
causing
the
greater
exposure
if
a
similar
use
scenario
is
found
for
both
chlorine
dioxide
and
sodium
chlorite.
The
reader
is
referred
to
USEPA
(
2005a)
for
the
derivation
of
the
riskbased
inhalation
RfC
values.
Page
17
of
58
Table
3.2.
Toxicological
Endpoints
Selected
for
Chlorine
Dioxide
(
and
Representative
of
Sodium
Chlorite).

Exposure
Scenario
Dose
Used
in
Risk
Assessment
(
mg/
kg/
day)
UF/
MOE
for
Risk
Assessment
Study
and
Toxicological
Effects
Acute
Dietary
An
acute
dietary
endpoint
was
not
identified
in
the
data
base
for
chlorine
dioxide.

Chronic
Dietary
NOAEL
=
3
mg/
kg/
day
UF
=
100
(
10x
inter­
species
extrapolation,
10x
intra­
species
variation)

FPQA
=
1
Chronic
PAD
=
0.03
mg/
kg/
day
Developmental
Toxicity
­
Rat
(
Orme
et
al.,
1985)­
based
on
depression
of
serum
T4
levels
in
pups
from
dosed
maternal
rats
and
delays
in
development
of
locomotor
and
exploratory
behavior
activity
at
14
mg/
kg/
day
Two­
generation
reproduction
toxicity
study
(
CMA,
1996)
­
decreases
in
absolute
brain
and
liver
weight,
and
lowered
auditory
startle
amplitude
at
LOAEL
of
6
mg/
kg/
day
Incidental
Oral
(
short­
and
intermediate
­
term)
NOAEL
=
3
mg/
kg/
day
MOE
=
100
See
summary
for
dietary
assessment
Dermal
(
All
Durationsa)
NOAEL=
3
mg/
kg/
day
MOE
=
100
See
summary
for
dietary
assessment
[
Assume
100%
dermal
absorption]

see
ADTC
endpoint
selection
document
for
explanation
of
NOAEL/
LOAEL
values
and
effects
(
USEPA
2005a)
Occupational
`
RfC'
=
0.009
mg/
m3
(
0.003
ppm)
b
Homeowner
short­
term
`
RfC'
=
0.14
mg/
m3
(
0.05
ppm)
b
Inhalation
toxicity
studies­
Rat:
Homeowner
short­
term:
Dalhamn,
1957
[
LOAEL
of
28
mg/
m3
(
10
ppm)]

Occupational
exposure:
Paulet
and
Debrousses,
1970,
1972
using
LOAEL
of
1.0
ppm
(
2.8
mg/
m3);
Dalhamn,
1957
using
NOAEL
of
0.1
ppm
(
0.28
mg/
m3).
Inhalation
Homeowner
long­
term:
Agency
RfC
methodology
used
to
derive
a
RfC
value
of
2
x
10­
4
mg/
m3
or
0.00007
ppm
(
USEPA,
2000)
(
Paulet
and
Debrousses,
1970,
1972)
selected
as
cocritical
studies
(
USEPA,
2005a)

aBased
on
the
use
of
an
oral
endpoint
for
dermal
risk
assessments
and
the
lack
of
a
dermal
absorption
study,
a
dermal
absorption
value
of
100%
as
default
will
be
used.
Short­
term
is
1
to
30
days;
Intermediate­
term
is
1
to
6
months;
and
long­
term
is
greater
than
6
months.
bunit
conversion:
ppm
=
(
mg/
m3
x
24.45)
/
mw.
For
chlorine
dioxide
1
ppm
=
2.8
mg/
m3
3.3
FQPA
Considerations
The
endpoint
selected
for
both
dietary
and
non­
dietary
exposures
was
based
upon
adverse
effects
observed
in
offspring
from
developmental
and
reproductive
toxicity
data.
Consistent
with
the
approach
used
by
the
EPA's
Office
of
Water
for
use
of
chlorine
dioxide
as
a
drinking
Page
18
of
58
water
disinfectant
(
Federal
Register
Vol.
63,
No.
61,
pages
15673­
15692,
March
31,
1998)
and
the
updated
guidance
on
selection
of
a
safety
factor
under
FQPA,
the
endpoint
selected
for
assessment
of
risk
from
dietary
and
non­
dietary
exposure
to
chlorine
dioxide
is
felt
to
be
protective
of
potentially
susceptible
populations
including
children,
based
upon
the
selection
of
an
endpoint
and
effects
observed
in
offspring
and
the
use
of
an
NOAEL
value
based
on
those
effects.
Therefore
it
can
be
concluded
that
an
additional
safety
factor
under
FQPA
is
not
necessary
in
this
case
for
dietary
and/
or
residential
risk
assessments,
and
that
the
traditional
uncertainty
factor
(
MOE)
of
100
for
intraspecies
and
interspecies
variation
will
support
the
safety
standard
of
`
reasonable
certainty
of
no
harm'
as
required
by
the
FQPA
statute
for
food­
use
pesticides
(
USEPA
2005).

4.0
RESIDENTIAL
AND
PUBLIC
ACCESS
PREMISES
4.1
Summary
of
Registered
Uses
Chlorine
dioxide
and/
or
sodium
chlorite
products
are
used
by
homeowners
as
disinfectants
as
well
as
to
control
mold
and
mildew.
For
this
assessment,
household
cleaning
products
have
been
grouped
together
to
be
represented
by
the
higher
application
rate
from
the
chlorine
dioxide
and
sodium
chlorite
products.
For
example,
EPA
Reg.
No.
9804­
3
is
representative
of
products
that
are
used
in
the
home
to
clean
floors,
bathroom
surfaces,
shower
stalls,
laundry
rooms,
and
hampers.

Sodium
chlorite
is
also
used
for
homeowner
treatments
of
circulation
systems
in
swimming
pools
and
spas.
The
pool
and
spa
product,
EPA
Reg.
No.
70060­
20,
is
formulated
as
a
solid
tablet.
In
addition,
chlorine
dioxide
has
a
registered
use
for
HVAC
systems.
Applications
to
residential
heating,
ventilating,
air­
conditioning
(
HVAC)
systems
are
not
generally
performed
by
the
homeowner,
but
rather
a
commercial
applicator
(
e.
g.,
EPA
Reg.
No.
9804­
1).
Therefore,
homeowner­
based
HVAC
applications
are
not
presented;
only
potential
exposures
during
post
application
activities.
Finally,
there
is
a
continuous
release
product
packaged
as
a
sachet
that
releases
chlorine
dioxide
as
a
gas
over
time
in
homes,
automobiles,
etc.

4.2
Dietary
Exposure/
Risk
Pathway
 
Place
holder
for
risk
assessment
document
4.3
Drinking
Water
Exposure/
Risk
Pathway
 
Place
holder
for
risk
assessment.

4.4
Residential
Exposure/
Risk
Pathway
4.4.1
Residential
Handler
Exposure
EPA
has
estimated
both
the
potential
dermal
and
inhalation
routes
of
exposure
for
residential
handlers.
The
dermal
and
inhalation
exposures
are
presented
in
separate
sections
below.
Page
19
of
58
4.4.1.1
Residential
Handler
Dermal
Exposure
and
Risk
The
following
equations
were
used
to
calculate
potential
dermal
doses
and
risks
to
handlers:

Daily
Exposure:
E
=
UE
*
AR
*
AT
Where:
E
=
amount
(
mg
ai/
day)
deposited
on
the
surface
of
the
skin
that
is
available
for
dermal
absorption;
UE
=
unit
exposure
value
(
mg
ai/
lb
ai)
derived
from
August
1998
PHED
data
or
from
CMA
data;
AR
=
normalized
application
rate
based
on
a
logical
unit
treatment,
such
as
acres,
square
feet,
gallons,
or
cubic
feet.
Maximum
values
are
generally
used
(
lb
ai/
A,
lb
ai/
sq
ft,
lb
ai/
gal,
lb
ai/
cu
ft);
and
AT
=
normalized
application
area
based
on
a
logical
unit
treatment
such
as
acres
(
A/
day),
square
feet
(
sq
ft/
day),
gallons
per
day
(
gal/
day),
or
cubic
feet
(
cu
ft/
day).

Daily
Dose:
ADD
=
E
*
(
ABS
/
BW)

Where:
ADD
=
absorbed
dose
received
from
exposure
to
a
pesticide
in
a
given
scenario;
in
the
case
of
chlorine
dioxide,
the
dermal
absorption
is
defaulted
to
100%
because
of
the
lack
of
data.
(
mg
pesticide
active
ingredient/
kg
body
weight/
day);
E
=
amount
(
mg
ai/
day)
deposited
on
the
surface
of
the
skin
that
is
available
for
dermal
absorption;
ABS
=
a
measure
of
the
amount
of
chemical
that
crosses
a
biological
boundary
such
as
the
skin
(%
of
the
total
available
absorbed);
and
BW
=
body
weight
determined
to
represent
the
population
of
interest
in
a
risk
assessment
(
kg).

Margins
of
Exposure:
MOE
=
(
NOAEL
or
LOAEL)
/
ADD
Where:

MOE
=
margin
of
exposure,
value
used
to
represent
risk;
NOAEL
or
LOAEL
=
dose
level
in
a
toxicity
study,
where
no
observed
adverse
effects
(
NOAEL)
or
where
the
lowest
observed
adverse
effects
(
LOAEL)
occurred
in
the
study;
and
ADD
=
average
daily
dose
or
the
absorbed
dose
received
from
exposure
to
a
pesticide
in
a
given
scenario
(
mg
pesticide
active
ingredient/
kg
body
weight/
day).

A
series
of
assumptions
and
exposure
factors
served
as
the
basis
for
completing
the
handler
risk
assessment
for
each
use
site
category.
Each
general
assumption
and
factor
is
Page
20
of
58
detailed
below.
Assumptions
specific
to
the
use
site
category
are
listed
in
each
separate
section
below.
The
general
assumptions
and
factors
used
in
the
risk
calculations
include:

$
Chlorine
dioxide
is
a
widely
used
disinfectant
and
has
a
large
number
of
use
patterns.
As
a
result,
AD
has
patterned
this
risk
assessment
on
a
series
of
likely
representative
scenarios
for
each
use
site
that
are
believed
by
AD
to
represent
the
vast
majority
of
chlorine
dioxide
uses.

$
The
toxicological
endpoint
of
concern
for
dermal
risks
is
from
a
reproductive
study;
therefore
the
average
body
weight
of
an
adult
female
handler
(
i.
e.,
60
kg)
was
used
to
complete
the
dermal
risk
assessment.

$
Exposure
factors
used
to
calculate
daily
exposures
to
handlers
are
based
on
applicable
data,
if
available.
For
lack
of
appropriate
data,
values
from
a
scenario
deemed
similar
enough
by
the
assessor
might
be
used.

$
The
maximum
application
rates
allowed
by
the
representative
labels
were
used
in
the
development
of
the
risk
estimates
(
see
Tables
2.1,
2.2,
and
2.3).

Those
assumptions
specific
to
the
residential
handler
assessment
are
as
follows:

$
Unit
Exposure
Values:
Dermal
unit
exposure
values
were
taken
from
the
proprietary
Chemical
Manufacturers
Association
(
CMA)
antimicrobial
exposure
study
(
MRID
42587501)
or
from
the
Pesticide
Handler
Exposure
Database
(
PHED,
1998).
o
For
mopping,
the
CMA
dermal
unit
exposure
value
for
ungloved
mopping
was
used
(
71.6
mg/
lb
ai).
This
value
is
based
on
data
collected
from
six
replicates
mopping
floors
and
receiving
exposure
via
contact
with
the
mop
or
with
the
bucket.
o
For
trigger­
pump
sprays,
the
PHED
dermal
unit
exposure
value
for
ungloved,
short­
pants,
and
short­
sleeved
clothing
scenario
for
aerosol
spraying
(
220
mg/
lb
ai)
was
used
as
a
surrogate
for
the
trigger
pump.
This
value
is
based
on
data
collected
from
30
dermal
and
15
hand
replicates
who
applied
the
spray
on
surfaces
(
only
15
hand
replicates
available
because
½
the
test
subjects
wore
chemical
resistant
gloves).
o
For
solid
place
(
tablets),
the
CMA
dermal
unit
exposure
value
for
placing
solids,
such
as
tablets,
is
10.8
mg/
lb
ai
(
ungloved).
This
value
is
based
on
only
one
replicate.
The
value
for
the
dermal
exposure
when
wearing
gloves
is
reduced
to
0.142mg/
lb
a.
i.
This
value
is
also
based
on
only
one
replicate
(
metal
working
fluid).
Page
21
of
58
$
Amount
handled/
treated:
The
amounts
handled/
treated
were
estimated
based
on
information
from
various
sources,
including
the
Standard
Operating
Procedures
(
SOPs)
for
Residential
Exposure
Assessments
(
2000).
In
certain
cases,
no
standard
values
are
available
for
some
scenarios.
Assumptions
for
these
scenarios
are
based
on
AD
estimates
and
could
be
further
refined
from
input
from
affected
sectors.
The
following
assumptions
were
made:

o
Trigger­
pump
sprayers:
0.5
liters
or
0.13
gal/
day
o
Mopping:
1
gal/
event
o
Swimming
pools:
20,000
gallons
Two
scenarios
(
mopping
and
spraying)
were
examined
for
residential
cleaning
purposes
in
this
risk
assessment
and
one
scenario
for
the
pool/
spa
application.
Table
4.1
provides
the
label
information
that
is
representative
of
the
high­
end
residential
cleaning
and
pool/
spa
treatment
scenarios
for
chlorine
dioxide
as
well
as
sodium
chlorite.
For
use
in
residential
cleaning,
sodium
chlorite
was
identified
for
the
high­
end
exposure.
Sodium
chlorite
has
the
only
swimming
pool
and
spa
use
on
the
labels
reviewed
for
this
assessment.

Table
4.1.
Exposure
Scenarios
Associated
with
Residential
Exposure
Assessed
in
this
Document
Representative
Use
Application
Method
EPA
Registration
Number
Application
Rate
(
lb
ai/
gal)
Exposure
Scenario
Assessed
Application
to
hard
surfaces
$
mop
$

triggerpump
sprayer
9804­
3
(
chlorine
dioxide)
0.002
lb
ai/
gal
Short­
term
Adult
Handler
(
dermal
and
inhalation)

Application
to
swimming
pools
and
spas
$
place
solid
(
tablets)
70060­
20
(
Sodium
Chlorite)
2
tablets
in
skimmer
and
2
tablets
in
hair/
lint
basket
to
clean
pool
circulation
system
per
10,000
gallons
of
water.
100
g
x
4
tablets
x
20%
ai
=
80
g
ai/
10,000
gal
=
1.8E­
5
lb
ai/
gallon
Short­
term
Adult
Handler
(
dermal
and
inhalation)

The
results
of
the
MOE
analysis
for
these
scenarios
are
presented
in
Table
4.2.
Although
the
dermal
endpoint
represents
short­,
intermediate­,
and
long­
term
durations,
the
exposure
duration
of
most
homeowner
applications
of
cleaning
products
and
pools
are
believed
to
be
best
represented
by
the
short­
term
duration.
The
toxicological
endpoint
is
based
on
an
oral
study
and
no
dermal
absorption
value
is
available.
Therefore
100%
dermal
absorption
was
assumed
for
chlorine
dioxide
and/
or
chlorite
ion
residues.
The
dermal
MOEs
for
the
general
use
on
floors,
etc.,
are
above
the
target
MOE
of
100,
and
therefore,
are
not
of
concern
(
i.
e.,
the
short­
term
dermal
MOEs
for
applications
to
hard
surfaces
are
3,200
for
the
trigger­
pump
sprayer
and
1,300
for
the
mopping).
The
short­
term
dermal
MOE
for
pool
and/
or
spa
treatments
is
46
without
the
use
of
gloves
and
the
MOE
is
500
with
the
use
of
gloves.
Page
22
of
58
Table
4.2.
Calculation
of
Short­
term
Dermal
MOEs
for
Residential
Handlers
Exposure
Scenario
Application
Ratea
(
lb
ai/
gal)
Amount
Handled/
Treated
Dailyb
(
gal)
Baseline
Dermal
Unit
Exposurec
(
mg/
lb
ai)
Baseline
Dermal
Dosed,
e
(
mg/
kg/
day)
Baseline
Dermal
MOEf
(
Target
MOE
=
100)

Mopping
(
CMA
data)
hard
surfaces
0.002
1
71.6
0.0024
1300
Trigger­
pump
sprayer
(
Aerosol
can
PHED
data
used
as
surrogate)
hard
surfaces
0.002
0.13
220
0.00095
3200
Solid
Place
(
Tablets)
Pools
&
Spa
water
circulation
systems
1.8E­
5
(
4
tablets
/
10,000
gal.
Pool
tablet
is
100
g
x
4
tablets
x
20%
ai
=
80
g
ai/
10,000
gal
=
1.8E­
5
lb
ai/
gal)
20,000
10.8
(
no
gloves)
0.065
(
no
gloves)
46
(
no
gloves)

0.412
(
gloves)
0.006
(
gloves)
500
(
gloves)

a
Application
rates
are
the
maximum
application
rates
determined
from
EPA
registered
labels
for
chlorine
dioxide,
sodium
chlorite,
and
sodium
chlorate.
b
Amount
handled/
treated
per
day
values
are
based
on
AD
estimates.
c
Dermal
unit
exposures
are
from
CMA
and
PHED.
d
Baseline
dermal:
Long­
sleeve
shirt,
long
pants,
no
gloves
for
mopping
and
short­
pants,
short­
sleeved
shirt,
and
no
gloves
for
spraying.
e
Dermal
dose
(
mg/
kg/
day)
=
[
unit
exposure
(
mg/
lb
ai)
*
dermal
absorption
(
1.0)
*
appl.
rate
(
lb
ai/
gallon)
*
gallons
handled
/
body
weight
(
60
kg).
f
MOE
=
NOAEL
(
mg/
kg/
day)
/
Daily
Dose
[
Where
short­
and
intermediate­
term
dermal
NOAEL
=
3
mg/
kg/
day].
Target
MOE
is
100.

4.4.1.2
Residential
Handler
Inhalation
Exposure
and
Risk
The
potential
inhalation
of
chlorine
dioxide
may
occur
from
off
gassing
during
application
of
the
aqueous
solution.
Chlorine
dioxide
has
the
potential
to
generate
a
gas
during
the
residential
uses
of
mopping
and
spraying.
However,
it
is
unlikely
that
levels
of
concern
for
chlorine
dioxide
would
be
generated
outdoors
while
treating
swimming
pools
&
spas
with
tablets
placed
into
water.

Of
the
three
inhalation
toxicological
endpoints
selected,
the
short­
term
homeowner
(
i.
e.,
not
a
continuous
exposure)
best
represents
the
inhalation
exposure
duration
of
residential
handlers.
The
short­
term
residential
RfC
is
0.05
ppm.

To
determine
the
potential
inhalation
handler
exposure
resulting
from
the
vapor
of
chlorine
dioxide
as
a
general
purpose
cleaner,
the
model
EFAST
(
Exposure
and
Fate
Assessment
Screening
Tool)
was
used
to
estimate
the
air
concentration.
OPPT/
EETD
has
developed
the
model,
EFAST,
to
estimate
air
concentrations.
More
information
and
access
to
the
EFAST
model
is
available
at
http://
www.
epa.
gov/
opptintr/
exposure/.
In
summary,
EFAST
Version
1.1
Page
23
of
58
bases
its
air
concentration
estimates
on
physical/
chemical
properties.
The
air
concentration
estimates
for
the
chlorine
dioxide
are
based
on
the
model's
standard
input
parameters.
The
following
information
is
presented
in
the
EFAST
model:

"....
it
is
assumed
to
contact
the
target
surface,
and
to
subsequently
volatilize
at
a
rate
that
depends
upon
the
chemical's
molecular
weight
and
vapor
pressure."

The
molecular
weight
of
chlorine
dioxide
is
67.45
g/
mol
and
the
vapor
pressure
is
>
760
mm
Hg
at
25
degrees
C.
EFAST
estimates
a
peak
air
concentration
as
well
as
a
daily
air
concentration.
The
peak
air
concentration
estimate
"...
is
the
highest
instantaneous
air
concentration
that
is
modeled
during
the
exposure
event."
This
peak
air
concentration
is
instantaneous
and
at
the
source
of
the
treatment
solution.
The
peak
concentration
is
not
a
useful
measurement
for
comparison
to
the
inhalation
RfC
selected.

EFAST
was
used
to
model
the
air
concentration
from
general
purpose
cleaners
using
an
application
rate
of
0.002
lb
ai/
gal
(
i.
e.,
weight
fraction
=
0.00024).
The
peak
instantaneous
air
concentration
is
0.265
mg/
m3
(
0.09
ppm)
and
the
average
daily
TWA
air
concentration
is
determined
to
be
0.00794
mg/
m3
(
0.003
ppm).

The
inhalation
endpoint
(
RfC)
for
one­
time
applications
is
0.05
ppm.
Based
on
the
average
daily
air
concentration
(
representing
both
application
and
post
application),
the
handler
inhalation
exposures
of
chlorine
dioxide
are
not
of
concern
(
i.
e.,
the
average
air
concentration
estimated
by
EFAST
of
0.003
ppm
is
below
the
RfC
of
0.05
ppm).

4.4.2
Residential
Post
Application
Exposure
Typically,
most
products
used
in
a
residential
setting
result
in
exposures
occurring
over
short­
term
time
duration
(
1
 
30
days).
If
the
products
are
used
on
a
routine
basis
(
i.
e.,
once
a
week)
and
the
active
ingredient
has
a
long
indoor
half­
life,
exposures
may
occur
over
an
intermediate­
term
time
duration
(
30
days
 
6
months).
However,
AD
does
not
have
residue
dissipation
data
or
reliable
use
pattern
data
including
the
frequency
and
duration
of
use
of
antimicrobial
products
used
in
the
residential
setting.
Therefore,
even
though
AD
does
not
believe
that
the
use
patterns
of
many
residential
products
result
in
intermediate­
term
exposure,
they
are
assessed
to
provide
an
upper
bound
estimate
of
exposure
(
e.
g.,
day
care
centers).
Note:
For
chlorine
dioxide
the
dermal
and
oral
endpoints
and
durations
are
identical.

For
the
purposes
of
this
screening­
level
assessment,
post
application
scenarios
have
been
developed
that
encompass
multiple
products,
but
still
represent
a
high­
end
scenario
for
all
products
represented.
Four
scenarios
have
been
considered:
(
1)
exposure
to
residue
from
hard
floors
that
have
been
cleaned
with
a
solution
containing
chlorine
dioxide,
(
2)
exposure
to
chlorine
dioxide
used
to
clean
residential
HVAC
systems,
(
3)
exposure
to
a
continuous
release
(
gas)
deodorizer,
and
(
4)
swimming.
Page
24
of
58
4.4.2.1
Hard
Surface/
Floor
Dermal
Exposure
to
Children
from
Treated
Floors
Exposure
Calculations
There
is
the
potential
for
dermal
exposure
to
toddlers
crawling
on
hard
floors
after
mopping
with
chlorine
dioxide
products
and
to
carpets
after
application
with
a
formulated
dust
product.
The
hard
floor
scenario
was
selected
because
it
represents
the
higher
amount
of
residue
transferred
(
i.
e.,
5%
residue
transfer
assumed
for
carpets
and
10%
for
hard
surfaces).
Exposures
and
MOEs
were
calculated
for
children
contacting
treated
hard
surface
floors
in
residential
homes
(
short­
term
exposure)
and
in
commercial
daycare
centers
(
intermediate­
term
exposure).
To
determine
toddler
exposure
to
floor
residues
(
mopping),
the
following
equation
was
used:

PDD
=
AR
x
DTF
x
DRF
x
CF1
x
CF2
x
SA
BW
where,
PDD
=
Potential
daily
dose;
AR
=
Application
rate
(
lb/
ft2);
DTF
=
Dermal
transfer
factor
(
fraction,
unitless);
DRF
=
Disinfectant
fraction
remaining
on
floor
(
unitless);
CF1
=
Conversion
factor
(
4.54x105
mg/
lb);
CF2
=
Conversion
factor
(
10.8
ft2/
m2);
SA
=
Surface
area
of
the
body
which
is
in
contact
with
floor
(
m2);
and
BW
=
Body
weight
(
kg)

Assumptions
 
Toddlers
(
3
years
old)
were
used
to
represent
the
1
to
6
year
old
age
group.
A
body
surface
area
of
0.657
m2
and
a
body
weight
of
15
kg
was
been
assumed,
which
are
the
median
values
for
3
year
olds
(
USEPA,
1997).
 
Generic
household
cleaners
are
commercially
available
in
a
large
range
of
concentrations.
It
is
assumed
that
one
gallon
of
diluted
treatment
solution
is
used
to
treat
1000
ft2
of
floor.
The
maximum
application
rate
on
the
chlorine
dioxide
and/
or
sodium
chlorite
product
labels
for
application
to
hard
surfaces
which
are
believed
to
encompass
floors
where
children
may
play
was
0.002
lb
ai/
gal.
Therefore,
the
application
rate
used
in
the
post
application
scenarios
was
0.000002
lb
ai/
ft2.
 
No
transferable
residue
data
were
available
that
could
be
used
to
estimate
the
transfer
of
chlorine
dioxide
or
chlorite
ion
from
the
floor
to
skin.
Therefore,
it
is
assumed
that
10%
of
the
deposition
rate
is
available
for
dermal
transfer
(
USEPA,
2000,
and
2001).
This
is
a
very
conservative
estimate
for
chlorine
dioxide
as
it
has
a
very
high
vapor
pressure
and
volatility
will
affect
the
amount
of
residue
deposited.
 
No
data
could
be
found
regarding
the
quantity
of
dilute
treatment
solution
left
on
the
floor
after
treatment.
It
has
been
assumed
that
25%
of
the
treatment
solution
remains
Page
25
of
58
on
the
floor
after
the
final
mopping
(
i.
e.,
some
solution
remains
in
the
mop
itself
and
some
in
the
bucket).
 
It
was
assumed
that
the
exposed
toddler
plays
regularly
on
the
treated
floor.
In
a
residential
home,
short­
term
exposure
duration
is
most
likely
since
homeowners
are
expected
to
clean
the
floor
only
intermittently.
In
a
commercial
daycare
center,
intermediate­
term
exposure
duration
is
likely
since
it
is
expected
that
the
floors
are
cleaned
on
a
routine
basis.

Results
The
calculations
of
the
short­
and
intermediate­
term
dermal
doses
and
MOEs
are
shown
in
Table
4.3.
The
dermal
MOEs
for
the
residential
settings
(
short­
term
MOE)
and
institutional
settings
(
intermediate­
term
MOE)
are
identical
because
the
endpoints
and
uncertainty
factors
are
the
same
for
both
durations.
The
estimated
dermal
MOE
of
280
is
not
of
concern
(
i.
e.,
above
the
target
MOE
of
100).

Table
4.3.
Short­
and
Intermediate­
term
Post
Application
Dermal
Exposures
and
MOEs
for
Children
Contacting
Treated
Floors
Exposure
scenario
Application
rate
(
lb
ai/
sq
ft)
Product
remaining
after
mopping
Percent
trans.
residue
Body
area
in
contact
with
floor
(
m2)
Potential
daily
dosea
(
mg/
kg/
day)
Dermal
MOEb
Hard
surfaces
­
residential
and
daycare
settings
2x10­
6
25%
10%
0.657
0.017
280
a
Potential
daily
dose
(
mg/
kg/
day)
=
[(
Application
rate,
lb
ai/
ft2)*(
conversion
factor,
454
g/
lb)*(
conversion
factor,
1,000
mg/
g)
*
(
conversion
factor,
1
ft2/
0.093
m2)
*
(
product
remaining
after
mopping,
25%)
*
(
dermal
transfer
factor,
10%)
*
(
body
surface
area
in
contact
with
floor,
0.657
m2)]
/
(
body
weight,
15
kg)
b
Dermal
MOE
=
NOAEL
(
mg/
kg/
day)
/
Potential
daily
dose
(
mg/
kg/
day)
[
Where
short­
and
intermediate­
term
dermal
NOAEL
(
derived
from
an
oral
study
and
100%
dermal
absorption
is
assumed)
is
3
mg/
kg/
day.
Target
MOE
=
100.

Child
Incidental
Ingestion
Exposure
to
Treated
Floors
Exposure
Calculations
In
addition
to
dermal
exposure,
toddlers
crawling
on
treated
hard
floors
will
also
be
exposed
to
chlorine
dioxide
or
chlorite
ion
residues
via
incidental
oral
exposure
through
hand­
tomouth
activity.
To
calculate
incidental
ingestion
exposure
to
these
chemicals
due
to
hand­
tomouth
transfer,
the
methodologies
established
in
the
Standard
Operating
Procedures
(
SOPs)
for
Residential
Exposure
Assessments
(
USEPA
2000
and
2001)
were
used.
These
use
assumptions
are
similar
to
those
used
in
calculating
dermal
exposures
for
toddlers
crawling
on
treated
hard
floors.
Because
the
incidental
oral
endpoints
and
uncertainty
factors
are
identical
for
short­
and
intermediate­
term
durations,
scenarios
for
children
at
day
care
centers
are
not
listed
separately.
Exposures
were
calculated
for
children
contacting
treated
floors
in
residential
homes
using
the
following
equations
for
hand­
to­
mouth
transfer
of
pesticide
residues
to
toddlers:

PDD
=
SR
x
DTF
x
SA
x
EF
x
ET
x
SE
x
CF1
Page
26
of
58
BW
where:
PDD
=
Potential
daily
dose
(
mg/
kg/
day);
SR
=
Indoor
surface
residue
(
µ
g/
cm2);
DTF
=
Dermal
transfer
factor
(
unitless
fraction);
SA
=
Surface
area
of
the
hands
that
contact
both
the
treated
area,
and
the
individuals
mouth
(
cm2/
event);
EF
=
Frequency
of
hand­
to­
mouth
events
(
events/
hr);
SE
=
Saliva
extraction
efficiency
(
unitless
fraction);
ET
=
Exposure
time
(
4
hrs/
day);
CF1
=
Unit
conversion
factor
(
0.001
mg/
µ
g);
and
BW
=
Body
weight
(
15
kg)

And
SR=
AR
x
DRF
x
CF2
x
CF3
where:
SR
=
Surface
residue
(
µ
g/
cm2);
AR
=
Application
rate
(
lb
ai/
ft2);
DRF
=
Disinfection
fraction
remaining
on
floor
(
unitless);
CF2
=
Unit
conversion
factor
(
4.54x108
µ
g/
lb);
and
CF3
=
Unit
conversion
factor
(
1.08x10­
3
ft2/
cm2)

Assumptions
 
Toddlers
(
3
years
old)
were
used
to
represent
the
1
to
6
year
old
age
group
and
are
assumed
to
weigh
15
kg,
the
median
for
male
and
female
toddlers
(
USEPA,
2000
and
2001).
 
Based
on
HED's
Residential
SOP,
it
was
assumed
that
the
surface
area
used
for
each
hand­
to­
mouth
event
is
20
cm2.
For
short­
term
exposures,
it
is
assumed
that
the
frequency
of
hand­
to­
mouth
events
is
20
events
per
hour
(
90th
percentile)
(
USEPA
2001).
A
separate
assessment
at
the
intermediate­
term
duration
is
not
necessary,
as
the
shortterm
assessment
is
more
conservative
because
the
frequency
of
hand­
to­
mouth
events
for
the
intermediate­
term
exposure
duration
is
less
than
the
short­
term
and
because
the
toxicological
endpoints
and
uncertainty
factors
are
the
same
for
both
durations.
 
The
exposure
time
was
4
hours
a
day
(
USEPA,
2000
and
2001).
 
The
saliva
extraction
efficiency
was
50%
(
USEPA,
2000
and
2001).
 
The
labels
did
not
provide
information
on
the
volume
of
disinfectant
to
be
used
for
cleaning
surfaces
such
as
floors.
It
was
assumed
that
the
diluted
treatment
solution
was
applied
at
a
rate
of
1
gallon
per
1,000
sq.
ft.
The
maximum
application
rate
on
the
product
labels
for
application
to
hard
surfaces
is
0.002
lb
ai/
gal
(
EPA
Reg.
No.
9804­
3).
Therefore,
the
application
rate
used
in
the
post
application
scenario
was
0.000002
lb
ai/
ft2.
 
No
data
could
be
found
regarding
the
quantity
of
dilute
treatment
solution
left
on
the
floor
after
treatment.
It
has
been
assumed
that
25%
of
the
treatment
solution
remains
on
Page
27
of
58
the
floor
after
the
final
mopping
(
i.
e.,
some
solution
remains
in
the
mop
itself
and
some
in
the
bucket).
 
No
transferable
residue
data
were
available
that
could
be
used
to
estimate
the
transfer
of
chlorine
dioxide
and
chlorite
ion
from
the
floor
to
skin.
Therefore,
it
was
assumed
that
10%
of
the
deposition
rate
is
available
for
dermal
transfer
(
USEPA,
2000
and
2001).

Results
The
calculation
of
the
short­
term
oral
doses
and
the
oral
MOEs
are
shown
in
Table
4.4.
The
oral
MOE
is
2,300
and
is
above
the
target
MOE
of
100.

For
the
short­
term
exposures,
it
was
necessary
to
determine
the
total
MOE
since
the
toxicity
effects
are
the
same
for
the
dermal
and
oral
routes.
The
short­
term
total
MOE
for
children
contacting
treated
floors
(
dermal
+
oral
routes)
is
250
which
is
greater
than
the
target
MOE
of
100,
and
therefore
is
not
of
concern.
The
total
MOE
was
estimated
using
the
following
equation:
Total
MOE
=
1
/
((
1/
MOEdermal)
+
(
1/
MOEoral))
where,
MOEdermal
=
280
and
MOEoral
=
2,300.

Table
4.4.
ST
Incidental
Oral
Post
Application
Exposures
and
MOEs
for
Children
Contacting
Treated
Floors
Exposure
Scenario
Appl.
Rate
(
lb
ai/
sq
ft)
Product
Remaining
after
Mopping
Surface
Residuea
(
µ
g/
cm2)
Percent
transferable
residue
Surface
area
mouthed
(
cm2/
event)
Exposure
Frequency
(
events/
hr)
Saliva
Extraction
Factor
Exp.
Time
(
hrs/
day)
Potential
Daily
Doseb
(
mg/
kg/
day)
Oral
MOEc
Hard
surfaces
­
residential
setting
2x10­
6
25%
0.245
10%
20
20
50%
4
0.0013
2,300
a
Surface
residue
(
µ
g/
cm2)
=
(
application
rate,
lb
ai/
ft2)*(
disinfectant
fraction
remaining
on
floor,
0.25)*(
conversion
factor
to
convert
lb
to
µ
g,
4.54E+
08
µ
g/
lb)*(
conversion
factor
to
convert
ft2
to
cm2,
1.08E­
03
ft2/
cm2)
b
Potential
daily
dose
(
mg/
kg/
day)
=
[(
surface
residue,
µ
g/
cm2)*(
transferable
residue,
0.10)*(
exposure
time,
4
hrs/
day)*(
surface
area
of
hands,
20
cm2/
event)*(
frequency
of
hand­
to­
mouth
activity,
20
events/
hr)*(
extraction
by
saliva,
50
%)*(
conversion
factor
to
convert
µ
g
to
mg,
0.001
mg/
µ
g)]/
(
body
weight,
15
kg)
c
MOE
=
NOAEL
(
mg/
kg/
day)
/
potential
daily
dose
(
mg/
kg/
day)
[
Where
short­
term
oral
NOAEL
=
3
mg/
kg/
day].
Target
MOE
=
100.

Child
Inhalation
Exposure
after
the
Treatment
of
Floors
Chlorine
dioxide
can
potentially
be
released
into
the
air
as
a
gas/
vapor
after
it
is
applied
as
an
aqueous
solution
to
hard
surfaces
such
as
floors.
At
this
time
there
are
no
air
concentration
data
available
to
assess
the
release
of
chlorine
dioxide
during
or
after
mopping
floors.
There
are,
however,
air
concentration
measurements
available
after
the
application
of
chlorine
dioxide
as
a
dust
treatment
on
carpets
(
Speronello
2005).
Although
there
are
limitations
to
this
study
(
e.
g.,
not
conducted
under
Good
Laboratory
Practices
(
GLPs),
minimal
information
is
available
in
the
study
report,
and
the
study
did
not
monitor
aqueous
applications),
it
is
the
only
data
source
available
at
this
time.
In
addition,
the
results
are
directly
applicable
to
the
carpet
dust
application
of
chlorine
dioxide
(
e.
g.,
EPA
Reg.
No.
58300­
16).
Finally,
a
theoretical
approach
to
estimating
chlorine
dioxide
air
concentration
is
also
presented
below
based
on
dilution
and
ventilation
Page
28
of
58
equations.

Monitoring
Data:

Speronello
(
2005)
measured
chlorine
dioxide
air
concentrations
in
a
10ft
x
10ft
x
8ft
room.
Chlorine
dioxide,
formulated
as
Sanitizer
71
powder,
was
applied
to
a
carpet
at
application
rates
of
0.5
gram/
ft2,
1.5
gram/
ft2,
and
2.5
gram/
ft2.
The
limit
of
detection
for
the
sampling
was
0.01
ppm.
Samples
were
collected
at
1,
36,
and
60
inches
above
the
carpet.
The
room
was
reportedly
ventilated
at
35
and
135
cfm,
however,
the
study
indicates
that
the
configuration
of
the
inlet/
outlet
exhaust
was
such
that
minimal
ventilation
actually
occurred.
One
experiment
per
application
rate
was
monitored
at
the
135
cfm
ventilation
rate
and
it
appears
that
a
similar
sampling
schedule
was
used
for
the
experiments
at
the
35
cfm
ventilation
rate.
Raw
data
tables
were
not
provided
but
the
data
were
presented
graphically.
It
is
unclear
for
what
durations
samples
were
collected
and
time
weighted
averages
(
TWAs)
were
not
reported.
The
results
indicate
that
at
the
lower
ventilation
rate
(
i.
e.,
35
cfm)
the
peak
concentration
of
chlorine
dioxide
was
measured
at
0.3
ppm
for
all
application
rates.
For
the
135
cfm
ventilation
experiment,
peak
air
concentrations
were
measured
as
0.1
ppm,
0.3
ppm,
and
0.5
ppm
for
the
0.5,
1.5,
and
2.5
gram/
ft2
rates,
respectively.
Air
samples
were
nondetect
(
i.
e.,
less
then
0.01
ppm)
after
3
to
4
hours.

To
determine
the
inhalation
risks
associated
with
chlorine
dioxide
vapors
as
a
result
of
the
carpet
dust
applications,
the
appropriate
exposure
duration
and
frequency
need
to
be
compared
to
an
inhalation
toxicity
endpoint
of
similar
duration
and
frequency.
Carpet
and/
or
mopping
hard
surface
floor
treatments
are
believed
to
be
intermittent
in
frequency.
Therefore,
the
short­
term,
single
exposure
inhalation
endpoint
for
residents,
0.05
ppm,
is
the
appropriate
endpoint
to
use
in
this
exposure
scenario.

The
air
concentration
data
available
in
this
study
are
peak
measurements
with
the
sampling
time
not
reported.
The
peak
concentrations
measured
in
the
first
3
or
4
hours
after
application
(
up
to
0.5
ppm)
exceed
the
level
of
concern
(
i.
e.,
RfC
of
0.05
ppm)
by
an
order
of
magnitude.
However,
the
peak
air
concentrations
for
chlorine
dioxide
decrease
below
the
level
of
concern
after
3
or
4
hours,
most
likely
earlier.
Actual
inhalation
risk
concerns
are
indeterminate
because
the
air
concentrations
in
the
room
available
for
children
to
breathe
are
only
measured
in
the
study
as
peak
concentrations
which
are
not
directly
comparable
to
the
time
weighted
average
(
TWA)
toxicity
value.
These
data
do,
however,
indicate
that
additional
study
information
and/
or
a
new
study
are
warranted
to
provide
a
reasonable
certainty
of
no
harm
for
children
(
or
adults)
in
rooms
treated
with
chlorine
dioxide.

Dilution
Ventilation
Approach:

In
the
dilution
and
ventilation
approach
to
determining
air
concentrations
in
a
room,
the
application
rate
from
EPA
Reg.
No.
9804­
3
is
used
(
USEPA
2005c).
As
a
bounding
estimate,
it
is
conservatively
assumed
that
the
concentration
in
the
dilute
cleaning
solution
is
immediately
released
as
the
initial
air
concentration
in
the
room.
From
this
initial
air
concentration,
the
ventilation
rate
of
the
room
and
the
half­
life
of
chlorine
dioxide
in
an
aqueous
solution
are
used
to
estimate
the
air
concentration
in
the
room
every
30
minutes.
The
results
are
a
bounding
Page
29
of
58
estimate
of
the
maximum
air
concentration
in
the
room.
Actual
results
will
be
lower
as
the
initial
concentration
of
chlorine
dioxide
in
the
air
would
not
be
equal
to
that
of
what
is
in
the
treatment
solution.
Furthermore,
the
half­
life
of
chlorine
dioxide
in
an
aqueous
solution
was
used
(
i.
e.,
30
minutes).
The
half­
life
of
chlorine
dioxide
in
air
is
expected
to
be
much
lower.
The
half­
life
in
the
aqueous
solution
was
used
because
the
gas
would
be
released
over
time
in
the
room
rather
then
immediately
as
assumed.

The
initial
concentration
of
chlorine
dioxide
in
the
aqueous
solution
is
0.6
ppm
derived
from
the
application
rate
of
EPA
Reg.
No.
9804.3.
This
product
is
mixed
as
a
0.1%
ai
solution
of
24
oz
of
product
per
gallon
of
water
and
it
is
assumed
that
1
gallon
of
a
treatment
solution
is
used
to
mop
the
floor
which
is
equivalent
to
681
mg
chorine
dioxide
(
i.
e.,
[
8
lb/
gal
density
x
0.001
ClO2
x
1
ga/
128
fl
oz]
x
24
fl
oz
product/
gal
x
1
gallon
mopping
solution
=
0.0015
lb
ai
of
treatment
solution
or
681
mg
ai.).
Assuming
all
of
the
681
mg
of
chlorine
dioxide
is
released
into
a
1,800
ft2
house
(
volume
=
1,800
ft2
x
8
ft
ceiling
=
14,400
ft3
or
408
m3)
the
air
concentration
would
be
0.6
ppm
(
i.
e.,
681
mg
ai/
408
m3
=
1.7
mg/
m3
or
0.6
ppm).
Note:
The
area
of
a
house
was
used
to
estimate
the
volume
of
the
house,
not
the
total
surface
area
of
the
house
mopped.

The
dilution
ventilation
equation
is
as
follows:

t
=
Vr/
Q
ln
[
Ci/
C]

Where:
t
=
time
required
in
minutes
C
=
desired
concentration
of
the
disinfectant
(
0.05
ppm)
Ci
=
initial
concentration
of
the
disinfectant
Vr
=
volume
of
area/
room
in
ft3
Q
=
air
flow
into
room,
in
ft3/
min.

Note:
The
above
equation
does
not
include
the
half
life
factor
for
chlorine
dioxide.
To
account
for
the
half­
life
the
following
equation
is
used
to
estimate
C/
Ci
:

C/
Ci
=
e
 
(
t/
0.693
x
Q/
Vr)(
ln2/
t0.5)

Where:
C,
Ci,
t,
Q
and
Vr
have
the
same
meanings
as
outlined
above
while
the
factor
ln2/
t0.5
represents
the
assumption
of
first
order
decay
for
chlorine
dioxide
gas.
t0.50
is
the
half­
life
of
chlorine
dioxide.
It
is
assumed
that
it
takes
longer
for
chlorine
dioxide
to
breakdown
from
aqueous
solution
than
when
it
is
in
gaseous
state.
The
most
cited
literature
for
the
half­
life
of
chlorine
dioxide
from
an
aqueous
solution
states
it
to
be
30
minutes.

Table
4.5
summarizes
the
concentrations
for
chlorine
dioxide
for
every
30
minutes.
The
results
indicate
that
for
an
assumed
room
ventilation
rate
of
43.2
ft3/
minute,
the
bounding
estimate
of
chlorine
dioxide
in
the
air
is
below
the
inhalation
level
of
concern
of
0.05
ppm
at
1.5
hours
after
treatment.
Based
on
this
conservative
bounding
estimate,
the
inhalation
of
chlorine
dioxide
during
off
gassing
from
the
treatment
solution
used
to
mop
floors
does
not
appear
to
be
a
risk
of
concern
if
there
is
no
reentry
during
the
first
hour
after
treatment
(
i.
e.,
1­
hr
REI).
To
Page
30
of
58
accurately
determine
the
initial
concentration
of
chlorine
dioxide
in
the
air
after
mopping,
air
monitoring
data
would
be
needed.

Table
4.5
Bounding
Estimate
of
Chlorine
Dioxide
over
Time
(
Mopping).
Time
(
minutes)
Time
(
hours)
Chlorine
Dioxide
(
ppm)
0
0
0.6
30
0.5
0.27
60
1
0.13
90
1.5
0.057
120
2
0.026
180
3
0.0055
240
4
0.0011
300
5
0.0002
360
6
0.00005
420
7
0.00001
480
8
0.000002
540
9
0.0000005
8­
hour
TWA
starting
0­
hrs
after
treatment
0.08
8­
hour
TWA
starting
1­
hr
after
treatment
0.02
4.4.2.2
Heating
Ventilating
and
Air­
Conditioning
(
HVAC)
Systems
There
is
one
product
registered
for
use
in
cleaning
HVAC
systems.
This
product,
OXINE
(
EPA
Reg.
No.
9804­
1),
is
a
registered
sanitizer
for
residential/
commercial/
institutional
HVAC
systems.
It
is
formulated
at
2
percent
chlorine
dioxide.
Label
use
directions
indicate
that
the
product
is
mixed
at
a
rate
of
3.24
fluid
ounces
product
per
gallon
of
water
with
an
activator
to
activate
the
chlorine
dioxide
(
500
ppm
ClO2).
The
aqueous
chlorine
dioxide
solution
is
then
sprayed
or
fogged
into
closed
and
sealed
duct
work.
After
application,
the
label
directions
indicate
that
the
" 
area
should
be
opened
and
aired
for
one
(
1)
hour
before
repopulating."
It
is
assumed
that
dermal
post
application
exposures
are
negligible
for
applications
to
HVAC
systems.
This
assumption
is
supported
by
the
deposition
samples
discussed
below
(
BCI
2002).
However,
it
is
assumed
that
post
application
inhalation
exposure
can
occur
when
people
reenter
a
building
after
application.

BCI
(
2002)
monitored
a
chlorine
dioxide
treatment
of
a
HVAC
system
in
a
2250
ft2
residence.
The
application
was
performed
at
the
maximum
labeled
rate
(
i.
e.,
aqueous
solution
of
500
ppm).
The
ambient
air
in
the
house
was
monitored
for
chlorine
dioxide
gas
during
and
after
the
application.
Deposition
of
the
chlorite
ion
was
measured
using
1
ft2
glass
plates
on
the
floor
of
each
room.
Results
of
the
study
indicated
that
the
deposition
samples
were
all
nondetect
(
LOD
not
reported).
The
air
concentrations
monitored
indicated
a
maximum
instantaneous
reading
of
0.02
ppm
and
the
average
of
the
readings
was
below
the
detection
limit
of
0.01
ppm.

The
short­
term
inhalation
RfC
for
chlorine
dioxide
is
0.05
ppm.
According
to
the
label,
the
frequency
of
HVAC
system
treatments
is
to
"
treat
as
required".
The
frequency
of
residential
(
and/
or
commercial/
intuitional)
HVAC
treatments
is
expected
to
be
minimal
(
one
treatment
per
year
may
be
an
overestimate).
In
addition,
the
half­
life
of
chlorine
dioxide
is
rapid.
Page
31
of
58
Therefore,
inhalation
exposure
is
expected
to
be
limited
to
short­
term
durations.
The
maximum
value
monitored
by
BCI
(
2002)
during
application
and/
or
reentry
was
0.02
ppm,
below
the
RfC
value
of
0.05
ppm.
Therefore,
there
are
no
inhalation
risks
of
concern.
4.4.2.3
Continuous
Release
(
Gas)
Deodorizer
Product
Use
in
Homes:

One
product
has
been
identified
that
is
registered
as
a
continuous
release
of
chlorine
dioxide
gas
in
homes
(
EPA
Reg.
No.
70060­
12).
The
product
is
packaged
as
a
pouch
or
sachet.
The
product
states
that
it
" 
controls
odor­
causing
bacteria,
mold
and
mildew
and
chemical
odors
in
confined
spaces "
and
is
for
use
in
households,
hospitals,
and
institutions.
The
product
is
packaged
in
5,
10,
20,
50,
100,
and
200
gram
pouches/
sachets.
Household
uses
include
refrigerators,
shoes,
closets,
laundry
hampers,
cupboards,
cabinets,
drawers,
diaper
pails,
pet
areas,
and
basements.
Other
use
sites
of
this
product
outside
the
home
include
gym
lockers,
automobiles,
boat
cabins,
and
trash
cans.

No
monitoring
data
are
available
to
determine
the
air
concentrations
in
the
home.
Therefore,
a
bounding
estimate
of
air
concentration
is
presented
based
on
the
application
rate
and
the
label­
referenced
longevity
of
the
pouches/
sachets.
According
to
the
label,
the
basement
rate
is
200
grams
of
product
per
500
ft2
of
basement
area
for
up
to
2
months
of
treatment.
A
500
ft2
basement
area
is
assumed
to
be
equivalent
to
a
volume
of
4,000
ft3
or
113
m3
(
i.
e.,
500
ft2
x
8
ft
ceiling).
A
linear
release
of
the
chlorine
dioxide
gas
is
assumed.
Based
on
the
rapid
half­
life
of
chlorine
dioxide
(~
30
minutes
for
aqueous
solution
and
reportedly
shorter
in
air),
it
is
assumed
that
a
gas
build
up
will
not
occur.
The
theoretical
constant
air
concentration
would
be
0.52
ppm
assuming
no
air
exchange
and
no
build
up
of
chlorine
dioxide
over
time
because
of
the
short
half­
life
(
i.
e.,
label
rate
of
200
grams
of
5%
ai
product/
500ft2
for
2
months,
assuming
an
8
ft
ceiling).
The
RfC
for
long­
term
continuous
exposure
is
0.00007
ppm.
Therefore,
the
theoretical
concentration
from
the
product's
release
is
of
concern.
This
bounding
estimate
of
exposure
can
be
refined
by
determining
residential
ventilation
rates,
identifying
sensitive
analytical
detection
methods
(
current
sampling
techniques
do
not
have
the
capability
of
monitoring
to
a
level
of
0.00007
ppm),
collecting
monitoring
data,
and
determining
the
number
of
hours
an
individual
is
exposed
in
treatment
areas.
However,
before
any
refinements
to
these
air
concentration
estimates
are
attempted,
it
should
be
determined
if
the
product's
efficacy
can
be
maintained
at
the
RfC
of
~
0.00007
ppm.

Product
Use
in
Automobiles:

There
are
data
available
to
assess
the
use
of
the
continuous
release
deodorizer
product
in
automobiles
(
e.
g.,
EPA
Reg.
No.
70060­
12).
Two
studies
were
submitted
that
measured
chlorine
dioxide
air
concentrations
in
automobiles
(
Wood
and
Gallo
1997,
and
Speronello
1998).

Wood
and
Gallo
(
1997)
measured
chlorine
dioxide
in
a
total
of
16
automobiles
(
8
cars
parked
outside
and
8
cars
parked
inside
a
garage).
Cars
were
parked
in
inside
and
outside
parking
lots
to
account
for
sunlight
degradation
of
chlorine
dioxide.
The
study
author
indicated
that
" 
approximately
half
the
chlorine
dioxide
released
was
consumed
by
sunlight".
Cars
parked
outside
were
treated
with
5,
15,
25,
and
50
gram
sachets
while
cars
parked
inside
were
Page
32
of
58
treated
with
5
and
25
gram
sachets.
An
Interscan
Digital
Chlorine
Dioxide
Analyzer
was
used
to
measure
chlorine
dioxide
inside
the
cars
(
LOD
appears
to
be
0.01
ppm).
To
sample
chlorine
dioxide
in
the
cars,
tubes
were
inserted
through
the
weather
stripping
of
the
doors
to
preclude
dilution
by
opening
the
doors.
Each
car
was
sampled
from
1
to
4
days.
Samples
were
taken
for
some
cars
at
2,
4,
8,
and
24
hours
after
placement
of
sachets
and
other
cars
at
24,
27,
29,
33,
and
50
hours
after
placement
of
sachets
and
finally,
some
at
1,
2,
4,
8,
48,
and
96
hours
after
placement
of
sachets.
Duplicate
and
triplicate
readings
were
recorded
at
each
sampling
interval
at
various
locations
in
the
cars
(
i.
e.,
floor,
bench,
or
face
for
a
total
of
2
or
3
samples
per
interval).
It
appears
that
reported
air
concentrations
represent
instantaneous
measurements.

The
maximum
reported
single
reading
for
outdoor
cars
was
0.19
ppm
for
the
50
gram
sachet
and
also
0.19
ppm
for
the
indoor
car
with
a
25
gram
sachet.
The
maximum
and
average
readings
for
all
sampling
intervals
are
reported
in
Table
4.6.
Although
some
of
the
maximum
single
reading
values
of
chlorine
dioxide
exceed
the
short­
term
residential
inhalation
toxicity
of
concern
(
i.
e.,
level
of
concern
is
a
RfC
of
0.05
ppm),
these
maximum
single
readings
are
not
meaningful
to
determine
risk
concerns
when
compared
to
the
short­
term
inhalation
RfC
selected
in
this
document.
It
is
more
appropriate
to
compare
the
peak
measurements
to
the
ACGIH
STEL
which
is
based
on
a
15­
minute
average.
The
highest
maximum
single
reading
of
0.19
ppm
from
this
study
does
not
exceed
the
STEL
of
0.3
ppm.
The
average
of
all
of
the
instantaneous
readings
is
below
the
RfC
and
the
STEL.
In
conclusion,
the
data
presented
by
Wood
and
Gallo
(
1997)
indicate
that
the
concentration
of
chlorine
dioxide
remains
below
the
STEL
and
the
average
of
the
single
measurements
does
not
exceed
the
RfC
of
0.05
ppm.
However,
a
more
appropriate
measurement
would
have
been
to
sample
over
a
period
of
time
that
is
representative
of
the
duration
people
spend
in
cars
to
obtain
a
time
weighted
average
(
TWA).

Table
4.6.
Maximum
and
Average
Chlorine
Dioxide
Measurements
in
Automobiles.
Weight
of
Chlorine
Dioxide
Sachets
Chlorine
Dioxide
Reading
(
ppm)
5
grams
15
grams
25
grams
50
grams
Cars
Parked
Outdoors
Maximum
single
reading
0.01
0.06
0.1
0.19
Average
of
all
readings
0.0005
0.009
0.011
0.029
Cars
Parked
Indoors
Maximum
single
reading
0.008
0.19
Average
of
all
readings
0.002
Not
Sampled
0.008
Not
Sampled
LOD
=
0.01
ppm.
"
Average
of
all
readings"
represents
the
average
where
nondetects
are
counted
as
zero.

Speronello
(
1998)
provided
limited
additional
information
on
chlorine
dioxide
measurements
inside
of
automobiles.
Two
cars
using
different
application
rates
were
monitored
in
this
study
(
problems
were
encountered
with
the
3rd
car
and
this
experiment
was
discontinued).
One
car
was
treated
with
a
20
gram
sachet
and
the
other
car
was
treated
with
three
20
gram
sachets.
Air
concentrations
in
this
study
were
measured
with
an
INTERSCAN
Digital
Compact
Portable
Analyzer
(
model
4335DG).
This
device
recorded
chlorine
dioxide
measurements
at
10
second
intervals
for
5
minutes.
Sampling
intervals
were
0,
1,
2,
4,
6,
8,
24,
101,
149,
and
192
hours
after
initial
placement
of
the
sachet.
All
of
the
5
minute
samples
in
the
car
treated
with
20
grams
of
chlorine
dioxide
are
below
the
detection
limit
of
0.05
ppm.
The
results
from
the
car
Page
33
of
58
with
the
exaggerated
application
rate
indicated
a
maximum
chlorine
dioxide
concentration
of
0.091
ppm.
However,
the
text
did
not
indicate
if
this
was
a
5
minute
sample
or
peak
10
second
interval
within
the
5
minute
measurement.
It
also
appears
that
some
of
the
data
tables
in
Speronello
(
1998)
are
missing
from
the
experiment
identified
as
"
Run
3".
The
data
table
for
"
Run
3"
only
includes
the
10
second
measurements
for
the
0
hours
after
treatment
interval.
The
results
of
this
second
study
do
not
raise
any
additional
concerns
for
peak
measurements,
however,
the
data
are
of
limited
use
to
determine
a
TWA
concentration
over
the
time
period
people
spend
in
cars.

4.4.2.4
Swimming
Pools
&
Spas
Sodium
chlorite
is
used
to
treat
circulation
systems
in
swimming
pools
&
spas
(
EPA
Reg.
No.
70060­
20).
The
use
directions
for
treating
the
circulation
systems
include
the
following
types
of
statements:

 
Do
not
add
this
product
through
any
automatic
dispensing
device;
 
Apply
product
when
no
persons
are
in
the
pool;
 
For
pools
leave
pump
off
for
6
to
12
hours
before
resuming
pumping
and
then
wait
at
least
8
hours
before
allowing
swimmers
to
enter
pool;
 
Frequency
of
application
is
once
every
3
 
4
weeks
for
pools
and
once
every
4
 
6
weeks
for
spas;
and
 
For
spas
wait
approximately
30
minutes
before
reusing
spa.

Based
on
the
intended
use
of
the
product,
swimming
in
pools
or
spas
treated
with
chlorine
dioxide
is
not
assessed
quantitatively.
When
use
directions
are
properly
followed,
dermal,
incidental
oral,
and
inhalation
exposures
to
chlorine
dioxide
residual
levels
after
the
cleaning
of
the
circulation
systems
are
expected
to
be
minimal.

4.4.3
Data
Limitations/
Uncertainties
There
are
several
data
limitations
and
uncertainties
associated
with
the
residential
handler
and
post
application
exposure
assessments.
These
include:

°
The
exposure
factors
used
to
calculate
daily
exposures
to
handlers
are
based
on
applicable
data,
if
available.
For
lack
of
appropriate
data,
values
from
a
scenario
deemed
similar
enough
by
the
assessor
were
used.
°
Surrogate
dermal
unit
exposure
values
were
taken
from
the
proprietary
Chemical
Manufacturers
Association
(
CMA)
antimicrobial
exposure
study
(
MRID
42587501)
or
from
the
Pesticide
Handler
Exposure
Database
(
PHED,
1998).
See
Appendix
A
for
summaries
of
these
data
sources.
°
The
amounts
handled/
treated
were
estimated
based
on
information
from
various
sources,
including
the
Draft
Standard
Operating
Procedures
(
SOPs)
for
Residential
Exposure
Assessments
(
2000)
and
the
Draft
SOPs
for
Occupational
Exposure
Assessments
(
2003).
In
certain
cases,
no
standard
values
were
available
for
some
scenarios.
Assumptions
for
these
scenarios
were
based
on
AD
estimates
and
could
be
further
refined
from
input
from
affected
sectors.
Page
34
of
58
°
The
full
study
report
for
the
HVAC
monitoring
(
BCI
2002)
needs
to
be
submitted.
°
The
two
studies
submitted
to
support
the
use
in
automobiles
appear
to
provide
instantaneous
readings
of
chlorine
dioxide
levels
rather
than
TWA.
5.0
RESIDENTIAL
AGGREGATE
RISK
ASSESSMENTS
AND
RISK
CHARACTERIZATION
The
aggregate
risk
assessment
will
be
conducted
in
the
overall
risk
assessment
for
chlorine
dioxide.
The
non­
dietary
uses
that
may
co­
occur
for
consideration
in
the
aggregate
assessment
include
the
dermal
and
incidental
oral
post
application
exposures
to
children
playing
on
treated
floors
and
handler
dermal
exposures
for
adults.

6.0
OCCUPATIONAL
EXPOSURE
AND
RISK
6.1
Occupational
Handlers
6.1.1
Dermal
Handler
Exposures
Potential
occupational
handler
exposure
can
occur
in
various
use
sites,
including
agricultural
premises,
food
handling,
commercial
and
institutional
premises,
medical
premises,
human
drinking
water
systems,
industrial
processes
and
water
systems,
application
to
material
preservatives,
and
swimming
pools
and
other
aquatic
areas.
Table
6.1
provides
the
representative
use
scenarios
that
were
assessed
in
this
risk
assessment.

Table
6.1.
Exposure
Scenarios
Associated
with
Occupational
Exposure
Assessed
in
this
Document
Representative
Use
Application
Method
EPA
Registration
Number
(
chemical
associated
with
use)
Application
Rate
(
lb
ai/
gal)
Exposure
Scenario
Assessed
Use
Site
Category
I
(
Agricultural
Premises
and
Equipment)
a
$

lowpressure
hand
wand
74602­
2
(
Sodium
Chlorite)
(
Application
rate
from
label,
2.5
fl
oz/
gal)*(
1
gal/
128
oz)*(
0.75
lb
ai/
gal)
=
0.015
$

triggerpump
sprayer
$
fogger
(
1
hour
REI
after
fogging)
74602­
2
(
Sodium
Chlorite)
(
Application
rate
from
label,
2.5
fl
oz/
gal)*(
1
gal/
128
oz)*(
0.75
lb
ai/
gal)
=
0.015
$
mop
9150­
2
(
Chlorine
Dioxide)
(
Application
rate
from
label,
3.25
fl
oz/
gal)*(
1
gal/
128
oz)*(
0.69
lb
ai/
gal)
=
0.018
Application
to
hard
surfaces
and
equipment
$
foaming
wand
9150­
11
(
Chlorine
Dioxide)
(
Application
rate
from
label,
0.25
gal
of
product*
0.10
lb
ai/
gal)
=
0.025
lb
ai/
gal.)
Apply
at
rate
of
4
to
6
gallons/
minute
to
inside/
outside
of
animal
trucks/
equipment.
Short­
and
Intermediateterm
(
ST
and
IT)
Adult
Handler
(
dermal
and
inhalation)
and
Adult
Bystander
and
Post
Application
(
dermal
and
inhalation)
Page
35
of
58
Table
6.1.
Exposure
Scenarios
Associated
with
Occupational
Exposure
Assessed
in
this
Document
Representative
Use
Application
Method
EPA
Registration
Number
(
chemical
associated
with
use)
Application
Rate
(
lb
ai/
gal)
Exposure
Scenario
Assessed
 
ULV
fogger
(
e.
g.,
Dramm
fogger)
74602­
2
(
Sodium
Chlorite)
(
Egg
house
label
rate,
1
gal
product
x
5%
ClO2)
per
50
gal
=
0.0083)

Use
Site
Categories
II
(
Food
Handling),
III
(
Commercial/
Institutional),
and
V
(
Medical)

$
mop
9150­
10
active
(
10589­
3
transferred)
(
Chlorine
Dioxide)
(
Application
rate
from
label,
5
oz/
gal)*(
1
gal/
128
oz)*(
0.49
lb
ai/
gal)
=
0.019
Application
to
hard
surfaces
and
equipment
without
food
contact
$

triggerpump
sprayer
21164­
3
(
Sodium
Chlorite)
(
Application
rate
from
label,
12
fl
oz/
gal)*(
1
gal/
128
oz)*(
0.86
lb
ai/
gal)
=
0.08
Application
to
foods
(
Fruit/
vegetable
rinse)
$
dip
74602­
2
(
Sodium
Chlorite)
(
Application
rate
from
label,
1.9
oz/
gal)*(
1
gal/
128
oz)*(
0.75
lb
ai/
gal)
=
0.011
ST/
IT
Adult
Handler
(
dermal
and
inhalation)
and
Adult
Post
Application/
Bystander
(
dermal
and
inhalation)

Use
Site
Category
VI
(
Human
Drinking
Water
Systems)

Application
to
water
systems
(
Water
Treatment
and
water
storage
systems)
$
metering
pump
9804­
1
(
Chlorine
Dioxide)
(
Application
rate
from
label,
3.25
fl
oz/
gal)*(
1
gal/
128
oz)*(
0.27
lb
ai/
gal)
=
0.007
ST/
IT
Adult
Handler;
Potential
for
inhalation
exposure
unknown
at
this
time.

Use
Site
Category
VII
(
Material
Preservatives)

Applications
to
MWFs
$
liquid
pour
9150­
2
(
Chlorine
Dioxide)
batch
method:
0.0001
(
per
week)

continuous
method:
8E­
7
(
per
day)

badly
contaminated
systems:
4E­
6
(
slug
dose)
ST/
IT
Adult
Handler
(
dermal
and
inhalation)
and
Long­
term
Dermal
and
Inhalation
for
Machinists.

Use
Site
Category
VIII
(
Industrial
Processes
and
Water
Systems)
Application
to
pulp
and
paper
white
water
systems
$
metering
pump
74602­
3
(
Sodium
Chlorite)
(
Application
rate
from
label,
15
gal/
100,000
gal
white
water
to
be
treated
or
4
gal/
100
tons
paper
produced)*(
0.86
lb
ai/
gal)
=
0.0001
lb
ai/
gal
white
water
or
3.44
lb
ai/
100
ton
paper
produced
ST/
IT
Adult
Handler
(
dermal
and
inhalation)
and
Adult
Bystander
(
inhalation)

Application
to
oil
systems
(
oil
wells
during
secondary
recovery
operations)
$
liquid
pour
9150­
2
(
Chlorine
Dioxide)
(
Application
rate
from
label,
1
gal/
10
gal)*(
0.69
lb
ai/
gal)
=
0.069.
Label
indicates
to
portion
1
part
of
this
solution
to
150
parts
reinjection
water.
ST/
IT
Adult
Handler
(
dermal
and
inhalation)
and
Adult
Bystander
(
inhalation)
Page
36
of
58
Table
6.1.
Exposure
Scenarios
Associated
with
Occupational
Exposure
Assessed
in
this
Document
Representative
Use
Application
Method
EPA
Registration
Number
(
chemical
associated
with
use)
Application
Rate
(
lb
ai/
gal)
Exposure
Scenario
Assessed
Use
Site
Category
XI
(
Swimming
Pools)

Application
to
public
swimming
pool
circulation
water
systems
(
Swimming
pools)
$
solid
place
(
tablets)
70060­
20
(
Sodium
chlorite)
4
tablet
/
10,000
gal
(
Pool
tablet
is
100
g
x
4
tablets
x
20%
ai
=
80
g
ai/
10,000
gal
=
1.8E­
5
lb
ai/
gal)
Short­
term
Adult
Handler
(
dermal
and
inhalation)

Use
Site
Category
XII
(
Aquatic
Areas)

Non­
potable
water
systems
(
e.
g.,
retention
basins
and
ponds,
decorative
pools
and
fountains)
$
liquid
pour
9150­
11
(
Chlorine
Dioxide)
0.00001
(
18
fl
oz
x
0.72%
ai
per
100
gallons
water)
ST/
IT
Adult
Handler
(
dermal
and
inhalation)

Use
Site
Category
XIII
(
HVAC)

Application
to
ventilation
systems
(
HVAC)
$
airless
sprayer
$
fogger
(
1hour
REI
after
fogging)
9804­
1
(
Chlorine
Dioxide)
(
Application
rate
from
label,
3.25
fl
oz/
gal)*(
1
gal/
128
oz)*(
0.27
lb
ai/
gal)
=
0.007
ST/
IT
Adult
Handler
(
dermal
and
inhalation)
and
Short­
term
Child
and
Adult
Post
Application
(
inhalation)

The
following
assumptions
and
unit
exposure
values
were
used
in
the
risk
assessment:

$
Unit
Exposure
Values:
Dermal
unit
exposure
values
were
taken
from
the
proprietary
Chemical
Manufacturers
Association
(
CMA)
antimicrobial
exposure
study
(
MRID
42587501)
or
from
the
Pesticide
Handler
Exposure
Database
(
PHED,
1998).
o
For
low
pressure
hand
wand,
the
CMA
dermal
unit
exposure
value
for
ungloved
use
of
a
low
pressure
spray
was
used
(
191
mg/
lb
ai).
This
value
is
based
on
data
collected
from
eight
replicates
that
hand
sprayed
carpet
using
200
psi,
and
then
used
a
push
broom
rake
to
raise
the
carpet
nap.
The
time
required
to
perform
this
activity
took
between
33
to
141
minutes.
o
For
fogging,
it
is
assumed
that
most
of
the
exposure
to
the
handler
will
be
due
to
preparing
the
fogger
and
that
the
handler
leaves
the
room
immediately
after
fogging
commences.
Therefore,
the
CMA
dermal
unit
exposure
value
for
ungloved
pouring
was
used
(
50.3
mg/
lb
ai).
This
value
is
based
on
data
collected
from
one
replicate
that
transferred
the
pesticide
from
a
large
container
to
a
smaller
measuring
or
pouring
container.
The
time
required
to
perform
this
activity
took
between
5
to
78
minutes.
o
For
mopping,
the
CMA
dermal
unit
exposure
value
for
ungloved
mopping
was
used
(
71.6
mg/
lb
ai).
This
value
is
based
on
data
collected
from
six
replicates
mopping
floors
and
receiving
exposure
via
contact
with
the
mop
or
with
the
bucket.
Page
37
of
58
o
For
airless
sprayer,
PHED
dermal
unit
exposure
values
for
ungloved
(
38
mg/
lb
ai)
and
gloved
(
14.3
mg/
lb
ai)
were
used.
These
values
are
based
on
data
collected
from
15
replicates
who
applied
a
house
stain
to
the
outside
of
a
house.
The
airless
sprayer
was
used
to
represent
the
spraying
of
HVAC
duct
work.
In
addition
to
airless
sprayers,
duct
work
applications
would
include
ULV
foggers,
robotic
spraying
systems,
and
various
electric
sprayers.
o
For
foam
applicator,
the
CMA
dermal
unit
exposure
value
for
smaller
applications
ungloved
use
of
a
low
pressure
spray
was
used
(
191
mg/
lb
ai).
This
value
is
based
on
data
collected
from
eight
replicates
that
hand
sprayed
carpet
using
200
psi,
and
then
used
a
push
broom
rake
to
raise
the
carpet
nap.
The
time
required
to
perform
this
activity
took
between
33
to
141
minutes.
Assume
PHED
airless
sprayer
equipment
as
a
surrogate
for
large
applications
such
as
to
animal
transport
vehicles.
o
For
metering
pump
into
human
drinking
water
systems
and
industrial
processes
and
water
systems,
the
unit
exposure
value
from
the
CMA
dermal
unit
exposure
value
for
gloved
metering
pump
of
a
preservative
is
used
(
0.00629
mg/
lb
ai).
This
value
is
based
on
data
collected
from
two
replicates.
o
For
liquid
pour,
the
CMA
preservative
dermal
unit
exposure
value
for
a
gloved
worker
was
used.
The
dermal
unit
exposure
is
0.135
mg/
lb
a.
i.
and
is
based
on
2
replicates.
Although
this
unit
exposure
is
based
on
minimal
replicates,
the
exposure
value
is
similar
to
the
one
found
in
PHED
for
a
similar
scenarios
o
For
place
solid
(
tablets)
into
public
swimming
pool
water
circulation
systems,
the
unit
exposure
value
from
the
CMA
dermal
unit
exposure
for
ungloved
use
is
10.8
mg/
lb
ai
and
0.412
mg/
lb
ai
for
gloved
use,
only
one
replicate
of
each.
o
For
trigger­
pump
sprays,
the
PHED
dermal
unit
exposure
value
for
the
aerosol
sprays
were
also
used
as
a
surrogate
for
the
trigger
pump.
The
PHED
dermal
unit
exposure
values
for
ungloved
(
190
mg/
lb
ai)
and
gloved
(
81
mg/
lb
ai)
were
used.
These
values
are
based
on
data
collected
from
15
replicates
in
which
the
aerosol
spray
was
applied
on
surfaces.

$
Amount
handled/
treated:
The
amounts
handled/
treated
were
calculated
based
on
AD
estimates
and
could
be
further
refined
with
input
from
affected
sectors.
The
following
assumptions
were
made:
o
Low­
pressure
hand
wand:
2
gal/
day
o
Trigger­
pump
sprayers:
1
liter/
day
(
0.26
gal/
day)
o
Airless
sprayer
for
the
HVAC
use
is
assumed
to
be
5
gallons
for
one
worker.
This
value
is
assumed
to
be
representative
of
either
a
commercial
applicator
treating
multiple
residential
homes
or
a
work
day
treating
a
commercial
building
(
5
gal)
o
Mopping:
it
was
assumed
that
two
gallons
of
solution
are
used
in
the
food
handling
and
commercial/
institutional/
industrial
setting
and
45
gallons
are
used
in
the
medical
setting.
The
reason
for
this
assumption
specific
to
medical
premises
is
because
in
hospitals,
a
janitor
cleans
approximately
28
rooms
a
day
and
must
change
the
cleaning
water
every
three
rooms
(
Helwig
2003)
o
Fogger
(
e.
g.,
HVAC):
1
quart
assumed
for
a
single
work
day
(
0.25
gal)
Page
38
of
58
o
Foam:
for
application
to
animal
transport
vehicles,
label
directed
4
to
6
gallons
per
minute
and
assume
applied
for
10
minutes.
Additional
information
on
this
use
scenario
is
warranted.
o
Water
storage
systems:
34,000
gal/
day
(
estimated
storage
capacity
of
water
system
for
100
people;
based
on
Occupational
SOPs,
assumption
of
170,000
gal/
day
for
population
of
<
500
people)
o
Pulp
and
Paper
process
water:
500
tons/
day
o
Oil
systems
(
oil
wells):
The
following
use
was
used
to
estimate
the
amount
of
ai
handled
per
day
during
oil­
well
activities.
Biocide
is
typically
added
directly
to
drilling
rig
mud
tanks
via
open
pouring.
Over
a
3
to
6
week
period,
while
a
13,000
ft
well
is
being
drilled,
1
to
2
drums
(
1
drum
=
42
gallons)
of
biocide
may
be
used
if
microbiological
problems
are
encountered.
Therefore,
the
shortterm
exposure
assessment
used
5.6
gallons
for
the
amount
of
biocide
handled
per
day
by
the
drilling
rig
worker
[
i.
e.,
(
2
drums
x
42
gal/
drum)
/
(
5
days/
week
x
3
weeks)
=
5.6
gal/
day].
The
intermediate­
term
exposure
assessment
used
2.8
gallons
for
the
amount
of
biocide
handled
per
day
by
the
drilling
rig
worker
[
i.
e.,
(
2
drums
x
42
gal/
drum)
/
(
5
days/
week
x
6
weeks)
=
2.8
gal/
day].
However,
since
the
volume
of
water
being
treated
in
secondary
recovery
operations
is
so
large
(
i.
e.,
1,000
barrels
per
day,
42
gal/
barrel,
closed
metering
system),
the
available
CMA
data
can
not
be
reliably
extrapolated
because
they
are
based
on
activities
that
handle
much
lower
volumes
and
possibly
different
techniques.
Therefore,
it
was
assumed
that
if
the
open
pour
handling
activities
for
the
other
oil
well
operations
resulted
in
MOEs
that
are
not
of
concern,
then
the
MOEs
for
the
closed
system
chemical
metering
into
secondary
recovery
operations
would
also
be
not
of
concern.
AD
requests
that
confirmatory
data
be
conducted
to
show
that
this
is
accurate.
o
Retention
ponds/
fountains:
10,000
gallons
o
Public
swimming
pool:
200,000
gallons
$
To
calculate
the
dermal
exposure
for
a
worker
treating
fruits
and
vegetables,
the
Consumer
Exposure
Pathway
of
the
Exposure
and
Fate
Assessment
Tool
(
CEM/
E­
FAST)
was
used.
CEM
calculates
conservative
estimates
of
inhalation
and
dermal
exposures
to
consumer
products.
Because
CEM
does
not
include
a
scenario
similar
to
treating
fruits
and
vegetables
via
dip/
rinse,
a
new
user­
defined
scenario
was
created
(
using
the
category
"
products
that
contact
skin
directly
(
dermal),
potential
dose").
Surrogate
exposure
factor
values
have
been
extracted
from
E­
FAST
defaults
provided
in
the
CEM
help
manual.
Assumptions
and
input
values
for
the
model
are
listed
in
Table
6.3.

The
calculated
dermal
MOEs
are
shown
in
Table
6.2.
Table
6.3
provides
the
CEM
model
inputs
and
results
for
the
fruit
and
vegetable
rinse
scenario.
Calculated
dermal
MOEs
less
than
the
target
MOE
of
100
were
found
for
the
following
scenarios:
Page
39
of
58
Agricultural
Premises
and
Equipment
°
application
to
hard
surfaces
via
low
pressure
hand
wand
(
MOE
=
31)
°
application
to
hard
surfaces
via
mopping
(
MOE
=
70)
°
foam
applicator
to
animal
transport
vehicles/
tractor
trailer
(
MOE
=
8)

Food
Handling,
Commercial/
Institutional,
and
Medical
Premises
and
Equipment
°
application
to
hard
surfaces
via
mopping
(
MOE
=
66
for
commercial
and
3
for
medical)

In
addition
to
the
above
handler
assessments,
the
dermal
exposure
to
machinists
contacting
chlorine
dioxide
when
used
as
a
material
preservative
in
metal
working
fluid
(
MWF)
is
presented
below.
There
is
a
potential
for
dermal
and
inhalation
exposure
when
a
worker
handles
treated
metalworking
fluids.
Because
of
the
high
vapor
pressure
of
chlorine
dioxide,
the
inhalation
route
of
exposure
is
not
assessed
in
the
typical
manner
(
i.
e.,
using
the
OSHA
PEL
for
oil
mist
x
percent
concentration
in
solution).
See
Sections
6.1.2
and
6.2
for
discussion
of
the
inhalation
route.

The
dermal
route
of
exposure
to
machinists
occurs
after
the
chemical
has
been
incorporated
into
the
metalworking
fluid
and
a
machinist
is
using/
handling
this
treated
endproduct
Short­,
intermediate­,
and
long­
term
exposure
estimates
were
derived
using
the
2­
hand
immersion
model
from
ChemSTEER.
The
model
is
available
at
www.
epa.
gov/
opptintr/
exposure/
docs/
chemsteer.
htm.
The
2­
hand
immersion
equation
is
as
follows:

PDR
=
SA
x
%
a.
i.
x
FT
x
FQ
BW
where:

PDR
=
Potential
dose
rate
(
mg/
kg/
day);
SA
=
Surface
area
of
both
hands
(
cm2);
%
a.
i.
=
Fraction
active
ingredient
in
treated
metalworking
fluid
(
unitless)
FT
=
Film
thickness
of
metal
fluid
on
hands
(
mg/
cm2)
FQ
=
Frequency
of
events
(
event/
day);
BW
=
Body
weight
(
kg)

Assumptions
 
The
surface
of
area
of
both
hands
is
840
cm2
(
US
EPA
1997)
 
The
body
weight
of
an
adult
female
is
60
kg
(
US
EPA
1997)
 
The
percent
active
ingredient
in
treated
metalworking
fluid
for
continuous
operations
(
label
specified
"
continuous"
rate
selected
because
this
is
a
long­
term
duration)
is
8E­
7
lb
ai/
gallon
or
0.00001
%
(
EPA
Registration
No.
9150­
2).
Three
rates
are
listed
on
the
product's
label
which
contains
5%
chlorine
dioxide:
(
1)
Batch
Method
is
32
fl
oz
product/
1,000
gallons
water­
based
cutting
oils;
(
2)
Continuous
Method
is
2
gallons
product/
1,000,000
gallons
water­
based
cutting
oils
(
2
gal
x
8
lb/
gal
x
0.05
ai
/
1,000,000
gallons
cutting
oil
=
8E­
7
lb
ai/
gal);
and
(
3)
Badly
Contaminated
Systems
is
10
gallons
product/
1,000,000
gallons
water
Page
40
of
58
based
cutting
oils.
[
To
convert
to
%
ai
=
8E­
7
lbai/
gal
x
454
g/
1
L
x
1000
mg
/
1
g
x
1
gal/
3.79
L
=
0.1
mg/
L
/
10,000
=
0.00001%
ai]
 
For
short­,
intermediate­
and
long­
term
durations,
the
film
thickness
on
the
hands
is
1.75
mg/
cm2,
which
was
extracted
from
the
document
entitled,
"
A
Laboratory
Method
to
Determine
the
Retention
of
Liquids
on
the
Surface
of
Hands."
The
film
thickness
is
based
on
a
machinist
immersing
both
hands
in
metalworking
fluid
and
then
partially
cleaning
hands
with
a
rag.
The
film
thickness
was
chosen
because
the
dermal
endpoint
for
short­,
intermediate­
and
long­
term
durations
is
based
on
systemic
effects
(
USEPA,
1991).

The
results
of
the
dermal
exposure/
risk
to
machinists
working
with
fluids
treated
with
chlorine
dioxide
and/
or
sodium
chlorite
are
presented
in
Table
6.4.
The
short­,
intermediate­,
and
long­
term
dermal
MOE
is
14,000,
and
therefore,
not
of
concern.
Page
41
of
58
Table
6.2.
Short­
and
Intermediate­
Term
Dermal
and
Inhalation
Exposures/
Risks
to
Occupational
Handlers
from
the
Use
of
Chlorine
Dioxide
Dermal
Unit
Exposuresc
(
mg/
lb
ai)
Baseline
Attired
PPE
(
with
gloves)
e
Exposure
Scenario
Application
Ratea
(
lb
ai/
gal)
Area
Treated
Dailyb
(
gal)
Baseline
PPE­
with
gloves
Dermal
Dosef
(
mg/
kg/

day)
Dermal
MOEg
Dermal
Dosef
(
mg/
kg/

day)
Dermal
MOEg
Agricultural
Premises
and
Equipment
Low
Pressure
Hand
Wand
(

CMAdisinfectant
hard
surfaces
0.015
2
191
NA
0.096
31
No
Data
No
Data
Liquid
Pour
(
CMA
Data
for
cooling
tower)
­­
fogger
scenario
hard
surfaces
0.015
0.188
50.3
10.1
0.0024
1,300
0.00047
6,300
Trigger­
pump
Sprayer
(
PHED
data
for
aerosol
can
used
as
surrogate)
hard
surfaces
0.015
0.26
190
81
0.012
240
0.0053
570
Mopping
(
CMA
data)
hard
surfaces
0.018
2
71.6
NA
0.043
70
No
Data
No
Data
Foam
Wand
Applicator
(
using
PHED
airless
sprayer)
animal
transport
vehicles
0.025
6
gal/
min
x
10
min
=

60
gallons
38
14.3
0.95
3
0.36
8
Food
Handling,
Commercial/
Institutional,
and
Medical
Premises
and
Equipment
2
0.045
66
Mopping
(
CMA
data)
hard
surfaces
0.019
45
71.6
NA
1.0
3
No
Data
No
Data
Trigger­
pump
Sprayer
(
PHED
data
for
aerosol
can
is
used
as
surrogate)
hard
surfaces
0.08
0.26
190
81
0.066
46
0.028
110
Human
Drinking
Water
Systems
Metering
Pump
(
CMA)
water
and
storage
systems
0.007
34000
NA
0.00629
No
Data
No
Data
0.025
120
Material
Preservatives
Liquid
Pour
(
CMA)
MWF
0.0001
(
Batch
Method)
300
NA
0.184
No
Data
No
Data
0.000092
33,000
Industrial
Processes
and
Water
Systems
Metering
Pump
(
CMA
data
for
pulp
&
paper)
paper
and
pulp
white
water
systems
0.0344
lb
ai/
ton
paper
500
tons
paper
NA
0.00454
No
Data
No
Data
0.0013
2,300
2.8
0.00043
6,900
Liquid
Pour
(
CMA
data
for
preservative)
oil
systems
0.069
5.6
NA
0.135
No
Data
No
Data
0.00087
3,500
Page
42
of
58
Table
6.2.
Short­
and
Intermediate­
Term
Dermal
and
Inhalation
Exposures/
Risks
to
Occupational
Handlers
from
the
Use
of
Chlorine
Dioxide
Dermal
Unit
Exposuresc
(
mg/
lb
ai)
Baseline
Attired
PPE
(
with
gloves)
e
Exposure
Scenario
Application
Ratea
(
lb
ai/
gal)
Area
Treated
Dailyb
(
gal)
Baseline
PPE­
with
gloves
Dermal
Dosef
(
mg/
kg/

day)
Dermal
MOEg
Dermal
Dosef
(
mg/
kg/

day)
Dermal
MOEg
Swimming
Pools
and
Aquatic
Areas
Liquid
Pour
(
CMA
data)
retention
ponds/
fountain
0.00001
10,000
NA
0.135
No
Data
No
Data
0.0045
670
Solid
Place
(
CMA)
public
pools
1.8E­
5
200,000
10.8
0.412
0.65
5
0.025
120
HVAC
Systems
Airless
Sprayer
(
PHED
data)
HVAC
0.007
5
38
14.3
0.022
140
0.0083
360
Liquid
Pour
(
CMA
data)
­­
fogger
scenario
HVAC
0.007
0.25
50.3
10.1
0.0015
2,000
0.00029
10,000
a
Application
rates
are
the
maximum
application
rates
determined
from
EPA
registered
labels
for
chlorine
dioxide,
sodium
chlorite,
and
sodium
chlorate.

b
Amount
handled
per
day
values
are
based
on
Residential
SOPs,
industry
sources,
and
AD
estimates.

c
Dermal
unit
exposures
are
from
CMA
and
PHED
studies.

d
Baseline
dermal:
Long­
sleeve
shirt,
long
pants,
and
no
gloves.

e
PPE
dermal
with
gloves:
baseline
dermal
plus
chemical­
resistant
gloves.

f
Dermal
dose
(
mg/
kg/
day)
=
[
unit
exposure
(
mg/
lb
ai)
*
dermal
absorption
(
1.0)
*
Appl.
rate
*
amount
handled
/
Body
weight
(
60
kg).

g
MOE
=
NOAEL
(
mg/
kg/
day)
/
daily
dose
[
Where
short­
and
intermediate­
term
dermal
NOAEL
=
3
mg/
kg/
day].
Target
MOE
is
100.
Page
43
of
58
Table
6.3.
E­
FAST/
CEM
Model
Inputs
and
Results
for
the
Fruit/
Vegetable
Rinse
Scenario
Parameter
Value
Rationale
Inputs
Weight
Fraction
of
Chemical
in
Product
0.073
Based
on
maximum
use
rate
listed
on
product
label
Hand
Surface
Area/
Body
Weight
Ratio
15.6
cm2/
kg
Derived
from
both
hands
being
immersed
in
the
dip
solution
(
EFAST
default
value
for
general
purpose
cleaner
scenario,
Versar,
1988)

Film
Thickness
0.00214
cm
Assumed
to
be
the
initial
thickness
of
water
uptake
on
hands
from
handling
a
rag
(
E­
FAST
default
value
for
general
purpose
cleaner
scenario,
Versar,
1988)

Density
of
Formulation
0.032
g/
cm3
Based
on
information
from
label
(
0.27
lb
ai/
gal
=
0.032
g/
cm3)

Dilution
Fraction
0.015
Derived
from
information
on
product
label
(
1.9
oz/
gal
=
0.015
gal/
gal)

Frequency
of
Events
per
Year
130
event/
yr
Assumed
5
days/
week
for
50
weeks/
yr
Number
of
Years
of
Use
57
yrs
Assumed
to
be
total
number
of
years
between
the
ages
of
18
and
75
Amount
Retained
on
Skin
0.000001
g/
cm2
Derived
from
product
of
the
film
thickness
on
the
skin's
surface
and
the
density
of
the
formulation
and
the
dilution
factor
Calculated
Results
Potential
Dermal
Dose
Rate
1.14e­
03
mg/
kg­
day
ADRpot
output
from
model
(
see
Appendix
B)

Calculated
MOE
2600
MOE
=
NOAEL
/
Daily
Dose
[
Where
dermal
NOAEL
=
3
mg/
kg/
day].

Table
6.4.
Short­,
Intermediate­,
and
Long­
Term
Risks
Associated
with
Post
Application
Exposure
to
Metalworking
Fluids
treated
with
Chlorine
Dioxide
(
Machinist)

Dermal
Inputs
Continuous
Feed
Method
%
a.
i.

(
EPA
Reg.
No.
9150­
2)
Hand
Surface
Area
(
cm2)
Film
thickness
(
mg/
cm2)
Frequency
(
event/
day)
Daily
Dermal
Dose
(
mg/
kg/
day)
(
a)
ST/
IT/
LT
Dermal
MOE
(
Target
MOE
=
100)
(
b)

0.00001
840
1.75
1
0.00025
12,000
a
Dermal
daily
dose
(
mg/
kg/
day)
=
[(%
active
ingredient
*
hand
surface
area*
dermal
absorption
factor
(
100%
for
all
durations)*
film
thickness
(
mg/
cm2)*
frequency
(
event/
day)]
/
body
weight
(
60
kg).
b
Dermal
MOE
=
NOAEL
(
mg/
kg/
day)
/
daily
dose
(
mg/
kg/
day)
[
Where:
ST/
IT/
LT
NOAEL
=
3
mg/
kg/
day
from
an
oral
study
assuming
100%
dermal
absorption].
Page
44
of
58
6.1.2
Inhalation
Handler
Exposures
Inhalation
exposure
to
the
release
of
chlorine
dioxide
gas
during
the
mixing/
loading/
application
of
products
producing
chlorine
dioxide
may
occur.
Because
the
inhalation
toxicological
endpoint
is
based
on
an
8­
hour
TWA,
the
assessment
of
handler
inhalation
exposures
is
assessed
as
a
combination
of
activities
throughout
a
work
day.
The
assessment
of
inhalation
exposure
is
presented
in
the
post
application/
bystander
section
(
Section
6.2).

As
indicated
above,
EPA
has
selected
an
8­
hour
TWA
inhalation
endpoint.
EPA
does
not
provide
a
separate
endpoint
for
short­
term
exposures
to
handlers.
Short­
term
releases
of
chlorine
dioxide
are
of
concern
for
accidental
releases/
leaks
and/
or
when
applicators
are
in
close
proximity
to
open
solutions
of
chlorine
dioxide.
EPA
assumes
that
the
ACGIH
15
minute
short
term
exposure
limit
(
STEL)
of
0.3
ppm
as
well
as
the
immediately
dangerous
to
life
or
health
(
IDLH)
limit
of
5
ppm
will
be
adhered
to
in
the
industries
using
chlorine
dioxide.

6.2
Occupational
Post
Application/
Bystander
Exposure
6.2.1
Dermal
Post
Application/
Bystander
Exposures
No
information
is
available
to
assess
post
application/
bystander
dermal
exposure
to
uses
in
agricultural
premises
as
well
as
food
handling,
commercial/
institutional
and
medical
premises;
human
drinking
water
facilities;
industrial
processes;
and
retention
ponds.
However,
dermal
post
application
exposure
to
chlorine
dioxide
is
expected
to
be
less
than
that
of
the
dermal
contact
of
children
playing
on
treated
floor
surfaces.
Therefore,
the
dermal
exposure
route
is
not
believed
to
be
of
concern
in
these
industries.

6.2.2
Inhalation
Post
Application/
Bystander
Exposures
Non­
Fogging
Uses
There
is
the
potential
for
the
off
gassing
of
chlorine
dioxide
during
some
applications
that
are
not
totally
enclosed
(
e.
g.,
spray
aqueous
solution,
mopping,
pouring,
etc).
Although
no
occupational
air
monitoring
data
have
been
submitted
to
assess
the
inhalation
route,
EPA
has
obtained
air
concentration
measurements
from
OSHA.
OSHA
maintains
a
data
base
known
as
the
Integrated
Management
Information
System
(
IMIS).
The
IMIS
entries
for
chlorine
dioxide
are
available
for
7
industry
Standard
Industrial
Classification
(
SIC)
codes.
Specific
uses
such
as
applicators,
bystanders
and
the
activities
involved
are
not
available.
The
SIC
codes
representing
the
chlorine
dioxide
data
in
IMIS
used
in
this
assessment
include:

 
SIC
0723
Crop
preparation
services
for
market;
 
SIC
1629
Heavy
construction;
 
SIC
2611
Pulp
mills;
 
SIC
2621
Paper
mills;
 
SIC
2819
Industrial
inorganic
chemicals;
 
SIC
2836
Biological
products;
and
Page
45
of
58
 
SIC
3999
Manufacturing
industries.

The
data
selected
for
this
analysis
include
only
those
samples
that
are
reported
as
8­
hour
TWA
measurements
from
personal
air
samplers.
Other
samples,
such
as
peaks
concentrations
and/
or
area
monitors,
have
been
omitted.
The
chlorine
dioxide
sampling
and
analytical
procedures
used
in
the
collection
of
the
data
in
IMIS
are
available
at
http://
www.
osha.
gov/
dts/
sltc/
methods/
inorganic/
id202/
id202.
html.
The
quantitative
LOD
from
this
method
is
0.004
ppm
for
a
4­
hour
sample
(
the
recommended
sampling
time).
The
reported
full
8­
hour
work
shift
samples
are
based
on
two
4­
hour
samples
collected
in
sequence.
The
inhalation
endpoint
selected
by
EPA
is
0.003
ppm,
just
below
the
OSHA
LOD
for
an
8­
hour
TWA
air
sample
[
i.
e.,
(
0.5
x
0.004
ppm
per
4
hrs)
+
(
0.5
x
0.004
ppm
per
4
hrs)=
0.004
ppm
per
8
hours].

The
summary
results
of
the
33
observations
taken
from
8­
hour
TWA
personal
air
samplers
for
chlorine
dioxide
are
provided
below
in
Table
6.5.
All
values,
including
½
LOD
are
above
the
EPA
selected
inhalation
reference
concentration
(
RfC)
of
0.003
ppm,
and
therefore,
are
of
concern.
Of
the
33
TWA
measurements
available,
21
of
those
measurements
were
below
the
LOD
of
0.004
ppm.
In
addition,
of
the
33
TWA
measurements,
only
3
were
at
or
above
the
OSHA
PEL
of
0.1
ppm.
For
nondetected
samples,
1/
2
the
detection
limit
for
an
8­
hour
sample
was
used
to
determine
the
summary.

Table
6.5.
Chlorine
Dioxide
8­
hour
TWA
for
Personal
Air
Samplers
from
OSHA's
IMIS
Data
Base.
Statistic
Chlorine
Dioxide
8­
hr
TWA
(
ppm)
MOE
Arithmetic
mean
±
std
0.034
±
0.096
50th%
tile
0.004
(
1/
2
8­
hr
LOD)
75th%
tile
0.008
90th%
tile
0.032
Maximum
0.42
Number
of
Observations
33
Number
of
Nondetects
21
te:
The
inhalation
endpoint
is
expressed
as
the
RfC.
Because
the
uncertainty
factors
are
included
in
the
RfC
a
separate
MOE
is
not
needed.
The
occupational
RfC
of
0.003
ppm
is
compared
directly
to
the
air
concentration
monitored
for
the
worker.
Air
concentrations
above
the
RfC
are
of
concern.
All
values,
including
the
LOD,
are
above
the
RfC.

Fogging
Uses
The
fogging
use
of
chlorine
dioxide
is
unique
such
that
no
persons
are
present
during
the
actual
application/
fogging.
There
is
also
a
greater
potential
for
chlorine
dioxide
gas
formation
from
fogging
then
an
aqueous­
based
application
such
as
mopping.
Therefore,
a
separate
assessment
is
presented
for
foggers
that
indicate
potential
inhalation
exposure
and
reentry
recommendations.
The
air
concentration
in
a
fogged
area
should
be
below
the
occupational
RfC
of
0.003
ppm
before
the
room
is
entered
by
persons
not
wearing
respiratory
protection.
In
the
fogging
assessment
below,
EPA
Reg.
No.
74602­
2
is
used
to
illustrate
potential
air
concentrations.
Page
46
of
58
Concentrations
of
chlorine
dioxide
were
estimated
for
buildings
after
fogging
applications.
Air
concentrations
were
calculated
using
the
Multi­
Chamber
Concentration
and
Exposure
Model
(
MCCEM
v1.2).
MCCEM
estimates
average
and
peak
indoor
air
concentrations
of
chemicals
released
from
products
or
materials
in
houses,
apartments,
townhouses,
or
other
residences.
Although
the
data
libraries
contained
in
MCCEM
are
limited
to
residential
settings,
the
model
can
be
used
to
assess
other
indoor
environments.
MCCEM
has
the
capability
to
estimate
inhalation
exposures
to
chemicals,
calculated
as
single
day
doses,
chronic
average
daily
doses,
or
lifetime
average
daily
doses.

The
product,
EPA
Reg
#
74602­
2
(
sodium
chlorite
with
a
5%
chlorine
dioxide
equivalent)
has
a
maximum
application
rate
for
egg
houses
of
0.0083
lb
ai/
gal
(
1000
ppm
chlorine
dioxide
treatment
solution).
This
particular
product
specifically
lists
a
Dramm
fogger
for
the
application
(
i.
e.,
ultra
low
volume
(
ULV)).
According
to
the
registrant,
the
Dramm
fogger
for
chlorine
dioxide
applications
uses
2.5
ounces
of
the
diluted
product
per
225,000
cubic
feet
(
USEPA
2006),
and
the
label
states
to
run
the
fogger
for
five
minutes.
Note:
This
labeled
rate
should
be
added
to
all
chlorine
dioxide
fogger
uses.
If
other
registrants
require
a
higher
application
rate,
these
rates
need
to
be
brought
to
EPA's
attention
during
the
development
of
the
chlorine
dioxide
RED.

Model
input
assumptions
for
MCCEM
and
the
calculated
exposures
are
presented
in
Tables
6.6
and
6.7
for
0.18
ACH
and
4
ACH,
respectively.
The
following
assumptions
were
made:

 
The
area
being
fogged
is
a
one­
chamber
barn
with
dimensions
of
300
ft
x
50
ft
x10
ft
(
AD
standard
assumption).
 
Two
different
air
exchange
rates
(
kACH)
were
used
in
the
calculations:
0.18
air
exchange
per
hour
(
ACH)
(
MCCEM
default
based
on
a
poorly
vented
residential
home)
and
4
ACH
based
on
the
rate
for
a
poultry
barn
(
Jacobson,
2005).
 
The
half­
life
of
chlorine
dioxide
is
30
minutes
(
0.5
hours)
in
an
aqueous
solution
(
believed
to
be
less
in
air
but
reliable
data
are
not
available).
Using
the
equation
t
kdecay
e
C
C
 
=
0
0
2
1
,
and
substituting
0.5
hours
for
"
t",
the
rate
of
decay
is
calculated
to
be
1.386/
hr.
 
Both
air
exchange
and
chemical
decay
can
be
modeled
as
first­
order
processes
for
a
wellmixed
single
chamber
(
i.
e.,
the
rate
of
chemical
loss
that
can
be
attributed
to
either
of
these
processes
is
proportional
to
the
quantity
of
chemical
in
the
chamber).
Therefore,
the
two
rates
(
kACH
and
kdecay)
can
be
added
together
to
form
a
single
loss
rate
(
kloss=
kACH+
kdecay),
such
that
t
kloss
e
C
t
C
 
=
0
)
(
.
This
value
was
used
for
the
"
Air
Exchange
Rate"
in
the
MCCEM
model
to
account
not
only
for
the
air
exchange,
but
also
the
decay.
 
Fogging
occurs
instantaneously,
so
that
the
entire
mass
of
product
is
mixed
homogeneously
with
the
indoor
air
as
soon
as
fogging
commences.

The
initial
concentrations
of
chlorine
dioxide,
as
indicated
in
Tables
6.6
and
6.7,
is
0.0116
mg/
m3
or
0.004
ppm.
Using
an
ACH
of
0.18,
an
8­
hr
TWA
of
less
than
0.003
ppm
(
0.0084
mg/
m3)
is
expected
with
no
REI.
Using
an
ACH
of
4/
hr,
an
8­
hr
TWA
of
less
than
0.003
ppm
(
0.0084
mg/
m3)
is
expected
without
an
REI.
A
detailed
report
is
presented
in
Appendix
C,
including
hourly
air
concentrations.
Although
there
appears
to
be
no
inhalation
risks
of
concern,
Page
47
of
58
a
1­
hour
REI
would
be
prudent.
Moreover,
potential
label
language
to
assure
proper
ventilation
if
rates
above
that
used
in
this
assessment
are
identified
for
existing
products
include:
­­
ten
air
exchanges,
or
­­
2
hours
of
mechanical
ventilation
(
i.
e.,
fans),
or
­­
4
hours
of
passive
ventilation
(
i.
e.,
windows,
vents),
or
­­
11
hours
of
no
ventilation
followed
by
1
hour
of
mechanical
ventilation,
or
­­
11
hours
of
no
ventilation
followed
by
2
hours
of
passive
ventilation,
or
­­
24
hours
of
no
ventilation
Table
6.6.
Short
and
Intermediate
Term
Inhalation
Risks
Associated
with
Post
Application
Exposure
to
Chlorine
Dioxide
After
Fogging
0.18
ACH
Parametera
Value
Rationale
Dimensions
300x50x10
ft,
15,000
ft2
floor
area,
150,000
ft3
(
4,248
m3)
volume
EPA
assumption
Air
Changes
per
Hour
(
ACH)*
1.566/
hr
Value
used
in
MCCEM
is
actually
the
ACH
rate
(
0.18/
hr)
plus
the
decay
rate
(
1.386/
hr)
a
Activity
Pattern*
8­
hour
Time
Weighted
Average
(
TWA)
starting
immediately,
1
hour,
and
12
hours
after
fogging
Based
on
product
=

s
reentry
interval
(
EPA
Reg#
74602­
2)

Application
Rate
0.0083
lb
ai/
gal
Product
label
Use
Rate
2.5
oz/
225,000
ft3
Manufacturer's
specifications
Amount
Applied
to
Room
1.16x10­
5
g/
m3
(
Use
rate)
x
(
Application
rate)
Concentration
in
Room
after
Fogging
(
initial
concentration
rate
at
time
0)*
0.0116
mg/
m3
Amount
applied
to
room
MCCEM
Output
Average
Concentration
over
8­
hrs
(
mg/
m3)
0­
hr
re­
entry:
0.00109
Average
of
MCCEMcalculated
air
concentrations
from
Hour
0
to
Hour
8
Average
Concentration
over
8­
hrs
(
mg/
m3)
1­
hr
re­
entry:
0.000227
Average
of
MCCEMcalculated
air
concentrations
from
Hour
1
to
Hour
9
Occupational
RfC
(
i.
e.,
level­
of­
concern)
8­
hour
TWA
0.0084(
mg/
m3)
Level­
of­
concern
not
exceeded
*
Used
as
MCCEM
input.
Default
values
from
MCCEM
were
used
for
all
inputs
not
listed
in
the
table
above
a
Half­
life
of
chlorine
dioxide
=
30
minutes
(
0.5
hr).
Using
the
equation
t
kdecay
e
C
C
 
=
0
0
2
1
and
substituting
0.5
hours
for
"
t",
the
rate
of
decay
is
calculated
to
be
1.386/
hr.
Page
48
of
58
Table
6.7.
Short
and
Intermediate
Term
Inhalation
Risks
Associated
with
Post
application
Exposure
to
Chlorine
Dioxide
After
Fogging
4
ACH
Parametera
Value
Rationale
Dimensions
300x50x10
ft,
15,000
ft2
floor
area,
150,000
ft3
(
4,248
m3)
volume
EPA
assumption
Air
Changes
per
Hour
(
ACH)*
5.386/
hr
Value
used
in
MCCEM
is
actually
the
ACH
rate
(
4.0/
hr)
plus
the
decay
rate
(
1.386/
hr)
a
Activity
Pattern*
8
hour
Time
Weight
Average
(
TWA)
starting
immediately,
30
minutes,
and
1
hour
after
fogging
Based
on
product
=

s
reentry
interval
(
EPA
Reg#
74602­
2)

Application
Rate
0.0083
lb
ai/
gal
Product
label
Use
Rate
2.5
oz/
225,000
ft3
Manufacturer's
specifications
Amount
Applied
to
Room
1.16x10­
5
g/
m3
(
Use
rate)
x
(
Application
rate)
Concentration
in
Room
after
Fogging
(
initial
concentration
rate
at
time
0)*
0.0116
mg/
m3
Amount
applied
to
room
MCCEM
Output
Average
Concentration
over
8­
hrs
(
mg/
m3)
0­
hr
re­
entry:
0.000475
Average
of
MCCEMcalculated
air
concentrations
from
Hour
0
to
Hour
8
Average
Concentration
over
8­
hrs
(
mg/
m3)
1­
hr
re­
entry:
2.18x10­
6
Average
of
MCCEMcalculated
air
concentrations
from
Hour
1
to
Hour
9
Occupational
RfC
(
i.
e.,
level­
of­
concern)
8­
hour
TWA
0.0084(
mg/
m3)
Level­
of­
concern
not
exceeded
*
Used
as
MCCEM
input.
Default
values
from
MCCEM
were
used
for
all
inputs
not
listed
in
the
table
above
a
Half­
life
of
chlorine
dioxide
=
30
minutes
(
0.5
hr).
Using
the
equation
t
kdecay
e
C
C
 
=
0
0
2
1
and
substituting
0.5
hours
for
"
t",
the
rate
of
decay
is
calculated
to
be
1.386/
hr.

In
a
second
fogging
example,
EPA
Reg.
No.
21164­
3
allows
chlorine
dioxide
fogging
and
misting
applications
while
workers
are
in
the
room
if
the
level
of
chlorine
dioxide
does
not
exceed
the
TLV­
TWA
of
0.1
ppm.
The
use
directions
are
as
follows:

" 
may
be
added
to
the
plant
misting
or
fogging
systems
to
deodorize
and
to
control
odor
causing
bacteria,
mold
and
mildew
in
food
processing
plants,
dairies,
bottling
plants,
poultry,
meat
and
fish
plants
and
animal
facilities
such
as
poultry
houses,
swine
pens,
calf
barns
and
kennels.
If
the
TLV­
TWA
is
to
be
exceeded,
turn
off
air
handlers
and
Page
49
of
58
vacate
people
and
livestock
from
the
rooms
to
be
fogged
or
misted.
Ventilate
for
15
minutes
prior
to
reentry.
Note
 
Be
careful
not
to
add
concentrated
acid
solutions
to
undiluted
DURA
KLOR
as
high
concentrations
of
chlorine
dioxide
gas
may
evolve.
The
concentration
of
chlorine
dioxide
in
the
diluted
DURA
KLOR
solution
should
not
be
allowed
to
exceed
0.5
ppm "

The
occupational
RfC
of
0.003
ppm
could
be
exceeded
based
on
these
use
directions
(
i.
e.,
workers
do
not
need
to
leave
treatment
area
unless
the
TLV­
TWA
of
0.1
ppm
is
exceeded).

EPA's
Risk­
based
RfC
versus
OSHA
PEL
It
is
also
important
to
note
that
the
OSHA
PEL
for
chlorine
dioxide
is
0.1
ppm.
Air
concentrations
above
the
PEL
are
assumed
to
be
mitigated
at
each
facility.
Facilities
using
chlorine
dioxide
are
not
required
to
mitigate
inhalation
exposures
until
the
air
concentration
reaches
0.1
ppm.
Based
on
the
occupational
inhalation
toxicological
endpoint
selected
for
chlorine
dioxide
(
i.
e.,
RfC
of
0.003
ppm),
levels
at
or
near
the
PEL
are
of
concern.
In
fact,
the
capability
(
i.
e.,
LOD)
of
the
OSHA
sampling
method
is
insufficient
for
the
occupational
RfC
presented
in
this
document.
Reconciliation
of
the
EPA
risk­
based
RfC
and
the
current
OSHA
standards
will
be
made
during
the
regulatory
decision
phase
of
the
Reregistration
Eligibility
Decision
(
RED)
for
chlorine
dioxide.
The
various
cited
chlorine
dioxide
levels
from
other
organizations
are
reported
in
Table
6.8
for
review
by
regulatory
managers.

Table
6.8
Chlorine
Dioxide
Regulatory
Levels.
Organization
Time/
Duration
Description
Air
Concentration
(
ppm)
OSHA
8­
hour
TWA
PEL
0.1
8­
hour
TWA
TLV
0.1
ACGIH
15­
minutes
STEL
0.3
10­
hour
TWA
REL
0.1
NIOSH
30­
minutes
(
escape)
IDLH
5
8­
hour
TWA
RfC
­
Occupational
0.003
"
Short­
term"
RfC
 
Residential
for
single
exposures
0.05
EPA
Continuous
(
24/
7)
RfC
 
Residential
0.00007
6.3
Data
Limitations/
Uncertainties
There
are
several
data
limitations
and
uncertainties
associated
with
the
occupational
handler
and
post
application
exposure
assessments.
These
include:

$
The
exposure
factors
used
to
calculate
daily
exposures
to
handlers
are
based
on
applicable
data,
if
available.
For
lack
of
appropriate
data,
values
from
a
scenario
deemed
similar
enough
by
the
assessor
were
used.

$
The
inhalation
toxicological
endpoints
of
concern
for
the
occupational
and
long­
term
residential
scenarios/
durations
are
below
the
limit
of
detection
for
chlorine
dioxide.

$
Specific
application
techniques
and/
or
worker
activities
are
not
available
in
OSHA's
IMIS
data
base.
Page
50
of
58
$
Surrogate
dermal
unit
exposure
values
were
taken
from
the
proprietary
Chemical
Manufacturers
Association
(
CMA)
antimicrobial
exposure
study
(
MRID
42587501)
or
from
the
Pesticide
Handler
Exposure
Database
(
PHED,
1998).
See
Appendix
A
for
summaries
of
these
data
sources.
o
The
amounts
handled/
treated
were
estimated
based
on
information
from
various
sources,
including
the
Draft
Standard
Operating
Procedures
(
SOPs)
for
Residential
Exposure
Assessments
(
2000)
and
the
Draft
SOPs
for
Occupational
Exposure
Assessments
(
2003).
In
certain
cases,
no
standard
values
are
available
for
some
scenarios.
Assumptions
for
these
scenarios
are
based
on
AD
estimates
and
could
be
further
refined
from
input
from
affected
sectors.
Page
51
of
58
7.0
REFERENCES
42587501
Popendorf,
W.;
Selim,
M.;
Kross,
B.
(
1992)
Chemical
Manufacturers
Association
Antimicrobial
Exposure
Assessment
Study:
Second
Replacement
to
MRID
41761201:
Lab
Project
Number:
Q626.
Unpublished
study
prepared
by
The
University
of
Iowa.
316
p.

ATSDR.
2004.
Agency
for
Toxic
Substances
and
Disease
Registry
(
ATSDR)
Toxicological
Profile
For
Chlorine
Dioxide
and
Sodium
Chlorite,
US
Department
of
Health
and
Human
Services.
September
2004.

BCI,
2002.
(
Need
to
get
full
citation
for
the
HVAC
air
monitoring
study.)

Gates,
Don.
1998.
The
Chlorine
Dioxide
HANDBOOK.
AWWA
Publishers.

Helwig,
D.
(
2003)
Personal
Communication
between
D.
Helwig
(
Johnson
Diversy,
Inc)
and
K.
Riley
(
Versar,
Inc.),
November
11,
2003.

Oak
Ridge
National
Laboratory.
2005.
Risk
Assessment
Information
System.
http://
risk.
lsd.
ornl.
gov/
tox/
tox_
values.
shtml
PHED
Surrogate
Exposure
Guide.
1998.
Estimates
of
Worker
Exposure
from
the
Pesticide
Handler
Exposure
Database
Version
1.1.
August,
1998.

Speronello,
Barry.
1998.
Worst­
Case
Release
Study
for
Automotive
Deodorizing
Products.
Engelhard
Corporation,
Iselin,
NJ.
Completed
date
March
12,
1998.

Speronello,
Barry.
2005.
Chlorine
Dioxide
Concentration
Over
a
Carpet
Treated
with
Sanitizer
71
Powder.
Engelhard
Corporation,
Iselin,
NJ.
Completed
date
January
18,
2005.

U.
S.
EPA.
1991.
Chemical
Engineering
Branch
Manual
for
the
Preparation
of
Engineering
Assessments.
Prepared
for
the
OPPT
by
IT
Environmental
Programs,
Inc.

USEPA.
1992.
Dermal
Exposure
Assessment:
Principles
and
Applications.
Interim
Report.
Office
of
Research
and
Development,
Washington,
D.
C.
January
1992.
EPA/
600/
8­
91/
011B.

USEPA.
1997.
Exposure
Factors
Handbook.
Volume
I­
II.
Office
of
Research
and
Development.
Washington,
D.
C.
EPA/
600/
P­
95/
002Fa.

USEPA.
2000.
Residential
SOPs.
EPA
Office
of
Pesticide
Programs 
Human
Health
Division.
Dated
April
5,
2000.

USEPA.
2001.
HED
Science
Advisory
Council
for
Exposure.
Policy
Update,
November
12.
Recommended
Revisions
to
the
Standard
Operating
Procedures
(
SOPs)
for
Residential
Exposure
Assessment,
February
22,
2001.
Page
52
of
58
USEPA.
2005a.
Chlorine
Dioxide/
Sodium
Chlorite
­
Report
of
the
Hazard
Identification
Assessment
Review
Committee
(
HIARC)
and
the
Antimicrobials
Division
Toxicity
Endpoint
Selection
Committee
(
ADTC).
Dated
March
29,
2005.

USEPA.
2005b.
Sodium
Chlorate:
Occupational
and
Residential
Exposure
Assessment
of
Antimicrobial
Uses
for
the
Reregistration
Eligibility
Decision
Document.
PC
Code
073301,
RED
Case
No.
4049,
DP
Barcode
D3112200.

USEPA.
2005c.
Exposure
Determination
from
a
Indoor
Disinfectant
(
One­
Time)
Use
of
Chlorine
Dioxide.
Dated
July
20,
2005.

USEPA.
2006.
Personal
communication
between
Tim
Leighton
(
EPA)
and
Ken
Howlett
(
Verox).
January
27,
2006.

Versar,
Inc.
1988.
Standard
Scenarios
for
Estimating
Exposure
to
Chemical
Substances
During
Use
of
Consumer
Products.

Wood,
Richard
and
Gallo,
Vanessa.
1997.
Aseptrol
Automotive
Field
Testing:
Chlorine
Dioxide
Air
Levels
Inside
Vehicle.
Engelhard
Corporation,
Iselin,
NJ.
Completed
date
November
14,
1997.
Page
53
of
58
APPENDIX
A:
Summary
of
CMA
data
and
PHED
Page
54
of
58
Chemical
Manufacturers
Association
(
CMA)
Data:
In
response
to
an
EPA
Data
Call­
In
Notice,
a
study
was
undertaken
by
the
Institute
of
Agricultural
Medicine
and
Occupational
Health
of
The
University
of
Iowa
under
contract
to
the
Chemical
Manufacturers
Association.
In
order
to
meet
the
requirements
of
Subdivision
U
of
the
Pesticide
Assessment
Guidelines
(
superseded
by
Series
875.1000­
875.1600
of
the
Pesticide
Assessment
Guidelines),
handler
exposure
data
are
required
from
the
chemical
manufacturer
specifically
registering
the
antimicrobial
pesticide.
The
applicator
exposure
study
must
comply
with
the
assessment
guidelines
for
"
Applicator
Exposure
Monitoring"
in
Subdivision
U
and
the
"
Occupational
and
Residential
Exposure
Test
Guidelines"
in
Series
875.
For
this
purpose,
CMA
submitted
a
study
on
28
February,
1990,
entitled
"
Antimicrobial
Exposure
Assessment
Study
(
amended
on
December
8,
1992)"
which
was
conducted
by
William
Popendorf,
et
al.
It
was
evaluated
and
accepted
by
Occupational
and
Residential
Exposure
Branch
(
OREB)
of
Health
Effect
Division
(
HED),
Office
of
Pesticides
Program
(
OPP)
of
EPA
in
1990.
The
purpose
of
this
CMA
study
was
to
characterize
exposure
to
antimicrobial
chemicals
in
order
to
support
pesticide
reregistrations
(
CMA,
1992).
The
unit
exposures
presented
in
the
most
recent
EPA
evaluation
of
the
CMA
database
(
U.
S.
EPA,
1999)
were
used
in
this
assessment.

The
Agency
determined
that
the
CMA
study
had
fulfilled
the
basic
requirements
of
Subdivision
U
­
Applicator
Exposure
Monitoring.
The
advantages
of
CMA
data
over
other
"
surrogate
data
sets"
is
that
the
chemicals
and
the
job
functions
of
mixer/
loader/
applicator
were
defined
based
on
common
application
methods
used
for
antimicrobial
pesticides.
A
few
of
the
deficiencies
in
the
CMA
data
are
noted
below:

!

The
inhalation
concentrations
were
typically
below
the
detection
limits,
so
the
unit
exposures
for
the
inhalation
exposure
route
could
not
be
accurately
calculated.

!

QA/
QC
problems
including
lack
of
either/
or
field
fortification,
laboratory
recoveries,
and
storage
stability
information.

!

Data
have
an
insufficient
amount
of
replicates.

The
Pesticide
Handlers
Exposure
Database
(
PHED):
The
Pesticide
Handlers
Exposure
Database
(
PHED)
has
been
developed
by
a
Task
Force
consisting
of
representatives
from
Health
Canada,
the
U.
S.
Environmental
Protection
Agency
(
EPA),
and
the
American
Crop
Protection
Association
(
ACPA).
PHED
provides
generic
pesticide
worker
(
i.
e.,
mixer/
loader
and
applicator)
exposure
estimates.
The
dermal
and
inhalation
exposure
estimates
generated
by
PHED
are
based
on
actual
field
monitoring
data,
which
are
reported
generically
(
i.
e.,
chemical­
specific
names
not
reported)
in
PHED.
It
has
been
the
Agency's
policy
to
use
"
surrogate"
or
"
generic"
exposure
data
for
pesticide
applicators
in
certain
circumstances
because
it
is
believed
that
the
physical
parameters
(
e.
g.,
packaging
type)
or
application
technique
(
e.
g.,
aerosol
can),
not
the
chemical
properties
of
the
pesticide,
attribute
to
exposure
levels.
[
Note:
Vapor
pressures
for
the
chemicals
in
PHED
are
in
the
range
of
E­
5
to
E­
7
mm
Hg.]
Chemical
specific
properties
are
accounted
for
by
correcting
the
exposure
data
for
study
specific
field
and
laboratory
recovery
values
as
specified
by
the
PHED
grading
criteria.

PHED
handler
exposure
data
are
generally
provided
on
a
normalized
basis
for
use
in
exposure
assessments.
The
most
common
method
for
normalizing
exposure
is
by
pounds
of
active
ingredient
(
ai)
handled
per
replicate
(
i.
e.,
exposure
in
mg
per
replicate
is
divided
by
the
amount
Page
55
of
58
of
ai
handled
in
that
particular
replicate).
These
unit
exposures
are
expressed
as
mg/
lb
ai
handled.
This
normalization
method
presumes
that
dermal
and
inhalation
exposures
are
linear
based
on
the
amount
of
active
ingredient
handled.
Page
56
of
58
APPENDIX
B:
Input/
Output
from
E­
FAST/
CEM
Page
57
of
58
CEM
Inputs
ID
Number:
Unknown
Product:
Fruit/
vegetable
rinse
Chemical
Name:
Sodium
Chlorite
Scenario:
User
Defined
Population:
Adult
Weight
Fraction
­
Median
(
unitless):
0.073
Weight
Fraction
­
90%
(
unitless):
0.073
Dermal
Inputs
Frequency
of
Use
­
Body
(
events/
yr):
130
SA/
BW
­
Body
(
cm2/
kg):
15.6
Assume
5
days/
week
for
50
weeks/
yr
Derived
from
both
hands
being
immersed
in
the
dip
solution
(
E­
FAST
default
value
for
general
purpose
cleaner
scenario)
Amount
Retained/
Absorbed
to
Skin
(
g/
cm2­
event):
1e­
06
Derived
from
product
of
the
film
thickness
on
the
skin's
surface
(
assumed
to
be
the
initial
thickness
of
water
uptake
on
hands
from
handling
a
rag:
0.00214
cm;
E­
FAST
default
value
for
general
purpose
cleaner
scenario)
and
the
density
of
the
formulation
(
0.27
lb
ai/
gal
=
0.032
g/
cm3)
and
the
dilution
factor
(
1.9
oz/
gal
=
0.015
gal/
gal)

Avg.
Time,
LADD
(
days):
2.74e+
04
Avg.
Time,
ADD
(
days):
2.08e+
04
Avg.
Time,
ADR
(
days):
1.00e+
00
CEM
Dermal
Exposure
Estimates
ID
Number:
Unknown
Scenario:
User
Defined
Population:
Adult
Years
of
Use
(
years):
57
SA/
BW
Body
(
cm2/
kg):
15.6
Frequency
of
Use
(
events/
year):
130
Exposure
Units
Result
AT
(
days)

Chronic
Cancer
LADDpot
(
mg/
kg­
day)
3.08e­
04
2.74e+
04
Chronic
Non­
Cancer
ADDpot
(
mg/
kg­
day)
4.06e­
04
2.08e+
04
Acute
ADRpot
(
mg/
kg­
day)
1.14e­
03
1.00e+
00
Page
58
of
58
LADD
­
Lifetime
Average
Daily
Dose
(
mg/
kg­
day)

ADD
­
Average
Daily
Dose
(
mg/
kg­
day)

ADR
­
Acute
Potential
Dose
Rate
(
mg/
kg­
day)

Note:
75
years
=
2.738e+
04
days
pot
­
potential
dose
Note:
The
general
Agency
guidance
for
assessing
short­
term,
infrequent
events
(
for
most
chemicals,
an
exposure
of
less
than
24
hours
that
occurs
no
more
frequently
than
monthly)
is
to
treat
such
events
as
independent,
acute
exposures
rather
than
as
chronic
exposure.
Thus,
estimates
of
long­
term
average
exposure
like
ADD
or
ADC
may
not
be
appropriate
for
use
in
assessing
risks
associated
with
this
type
of
exposure
pattern.
(
Methods
for
Exposure­
Response
Analysis
for
Acute
Inhalation
Exposure
to
Chemicals
(
External
Review
Draft).
EPA/
600/
R­
98/
051.
April
1998