September
16,
2003
1
RISK
SCREEN
ON
THE
USE
OF
SUBSTITUTES
FOR
OZONE­
DEPLETING
SUBSTANCES
REFRIGERATION
AND
AIR
CONDITIONING
End­
Use:
All
HCFC
and
R­
502
End­
Uses
Refrigerant:
SUVA
®
407C
or
R­
407C
This
risk
screen
contains
no
Clean
Air
Act
(
CAA)
Confidential
Business
Information
(
CBI)
and,
therefore,
can
be
disclosed
to
the
public.

1.
INTRODUCTION
Stratospheric
ozone­
depleting
substances
(
ODS)
are
being
phased
out
of
production
in
response
to
a
series
of
diplomatic
and
legislative
efforts,
including
the
Montreal
Protocol
and
the
Clean
Air
Act
Amendments
of
1990
(
CAAA).
The
U.
S.
Environmental
Protection
Agency
(
EPA),
as
authorized
by
Section
612
of
the
CAAA,
has
developed
a
program
to
evaluate
the
human
health
and
environmental
risks
posed
by
alternatives
to
ODS.
The
main
purpose
of
EPA's
program,
called
the
Significant
New
Alternatives
Policy
(
SNAP)
program,
is
to
identify
acceptable
and
unacceptable
substitutes
for
ODS
in
specific
end­
uses.

EPA's
decision
on
the
acceptability
of
a
substitute
is
based
largely
on
the
findings
of
a
screening
assessment
of
potential
human
health
and
environmental
risks
posed
by
the
substitute
in
specific
applications.
EPA
has
already
screened
a
large
number
of
substitutes
in
many
enduses
within
all
of
the
major
ODS­
using
sectors,
including
refrigeration
and
air
conditioning;
solvent
cleaning;
foam­
blowing;
aerosols;
fire
extinguishing;
adhesives,
coatings,
and
inks;
and
sterilization.
The
results
of
these
risk
screens
are
presented
in
a
series
of
background
documents
that
are
available
in
this
docket.

The
purpose
of
this
report
is
to
supplement
EPA's
background
document
on
the
refrigeration
and
air
conditioning
sector1
(
hereinafter
referred
to
as
the
Background
Document)
by
adding
to
the
list
of
potential
substitutes
for
specific
end­
uses
of
R­
502
and
HCFC
blends
in
this
sector.
The
reader
is
referred
to
this
reference
for
an
additional
discussion
of
different
methodologies
used
to
conduct
risk
screens.
The
potential
risks
associated
with
use
of
the
constituents
of
this
blend
in
the
refrigeration
and
air
conditioning
end
use
have
been
examined
at
length
in
the
Background
Document.

1
EPA
1994.
Significant
New
Alternatives
Policy
Technical
Background
Document:
Risk
Screen
on
the
Use
of
Substitutes
for
Class
I
Ozone­
depleting
Substances:
Refrigeration
and
Air
Conditioning.
Stratospheric
Protection
Division.
March,
1994.
September
16,
2003
2
Occupational
exposure
modeling
was
performed
to
ensure
that
use
of
the
proposed
blend
in
the
applications
listed
above
did
not
pose
unacceptable
risk
to
workers.
Consumer
exposure
modeling
was
performed
to
examine
potential
catastrophic
releases
for
each
of
the
chemical
constituents
of
the
proposed
blend.

Section
2
of
this
report
summarizes
the
results
of
the
risk
screen
for
the
proposed
substitute
blend
listed
in
Table
1.
The
remainder
of
the
report
is
organized
similarly
to
the
Background
Document:
Section
3
presents
the
toxicity
values
used
for
the
risk
screen,
Section
4
presents
the
results
of
the
atmospheric
assessment,
Sections
5
and
6
discuss
occupational
and
general
population
exposures,
respectively.
Section
7
discusses
consumer
exposure,
Section
8
addresses
flammability
concerns,
and
Section
9
discusses
potential
increases
in
atmospheric
releases
of
volatile
organic
compounds
(
VOCs).

TABLE
1.
PROPOSED
SUBSTITUTE
BLEND
Refrigerant
Blend
(
Trade
Name)
Constituents
Percent
by
Weight
CAS
Number
HFC­
32
(
also
known
as
difluoromethane)
23
75­
10­
5
HFC­
125
(
also
known
as
pentafluorethane)
25
354­
33­
6
SUVA
®
407C
HFC­
134a
(
also
known
as
1,1,1,2­
tetrafluoroethane)
52
811­
97­
2
2.
SUMMARY
OF
RESULTS
SUVA
®
407C
is
recommended
for
SNAP
approval
for
all
the
proposed
end
uses.
EPA's
risk
screen
indicates
that
the
use
of
the
proposed
substitute
will
be
less
harmful
to
the
atmosphere
than
the
continued
use
of
R­
502
and
most
HCFC
blends.
No
significant
risks
to
workers
or
consumers
are
estimated
based
on
occupational
and
consumer
exposure
modeling.
Additionally,
general
population
exposure
to
the
substitute
is
expected
to
be
below
levels
of
concern
for
noncancer
risks.
1
For
applications
of
this
and
all
other
refrigerants,
EPA
recommends
that
American
Society
of
Heating,
Refrigerating
and
Air­
Conditioning
Engineers
(
ASHRAE)
Standards
15
and
34
be
followed.

1
There
is
no
promulgated
Cancer
Slope
Factor
for
any
of
the
components
of
this
refrigerant.
Further,
based
on
similarity
to
other
highly
metabolized
compounds
of
low
toxicity
(
1,1,­
difluoroethane),
there
are
no
current
data
to
indicate
that
these
compounds
would
be
carcinogenic.
September
16,
2003
3
3.
TOXICITY
REFERENCE
VALUES
FOR
SUBSTITUTES
To
assess
potential
health
risks
from
exposure
to
this
substitute
for
ODS
in
the
refrigeration
and
air­
conditioning
sector,
EPA
identified
the
relevant
toxicity
threshold
values,
including
available
occupational
exposure
limits
(
OELs),
for
comparison
to
modeled
exposure
concentrations
for
different
scenarios.
For
the
occupational
exposure
analysis
provided
in
this
risk
screen,
potential
risks
from
chronic
worker
exposure
were
evaluated
by
comparing
exposure
concentrations
to
values
derived
by
EPA,
namely
acceptable
exposure
levels
(
AELs).
Potential
risks
from
short­
term
occupational
exposures
were
also
evaluated
through
comparison
with
values
derived
by
EPA,
namely
short­
term
exposure
levels
(
STELs).
Reference
concentrations
(
RfCs)
were
used
to
assess
risks
to
the
general
population
from
exposure
to
ambient
air
releases
and
to
assess
potential
risks
associated
with
chronic
consumer
exposures.
The
OELs
and
RfCs
used
for
this
assessment
are
shown
in
Table
2.
EPA's
approach
for
identifying
or
developing
these
values
is
discussed
in
Chapter
3
of
the
Background
Document.

TABLE
2.
TOXICITY
THRESHOLD
VALUES
AEL
(
Long­
term
Exposure)
STEL
(
Short­
term
Exposure)
a
Cardiotoxic
LOAEL
Cardiotoxic
NOAEL
Reference
Concentration
(
RfC)
Chemical
ppm
ppm
ppm
ppm
ppm
mg/
m3
HFC­
32
1,000
4,000
350,000
300,000
24b
51
HFC­
125
1,000
4,000
100,000
75,000
Not
Available
Not
Available
HFC­
134a
1,000
4,000
80,000
40,000
19.17
80
Source:
AIHA
1999,
NRC
1996,
Hardy
et
al.
1992,
EPA
1993,
EPA
1995,
PAFT
1996.
aTLV­
STEL
(
Threshold
Limit
Value
Short­
Term
Exposure
Limit),
a
workplace
standard
sometimes
used
as
a
level
of
concern
for
emergency
response.
A
chemical's
TLV­
STEL
is
the
maximum
time­
weighted
average
concentration
of
that
chemical
in
the
air
to
which
workers
may
be
exposed
for
up
to
15
minutes.
bCurrently
there
is
no
RfC
available
for
HFC­
32.
In
the
absence
of
an
RfC,
a
value
of
24
ppm
is
proposed,
which
is
essentially
the
AIHA
WEEL
of
1,000
ppm
which
was
converted
to
an
exposure
period
for
the
general
population
and
to
which
was
applied
an
uncertainty
factor
to
account
for
sensitive
subpopulations
(
e.
g.,
children,
elderly).
Therefore,
the
equation
used
is
the
following:
1000
x
8
hours/
24
hours
x
5
days/
7
days
x
1/
10
=
24
ppm.
According
to
PAFT,
HFC­
32
has
very
low
acute
and
subchronic
inhalation
toxicity,
is
not
a
developmental
toxicant,
and
is
not
mutagenic.
Therefore,
we
do
not
believe
additional
uncertainty
factors
need
to
be
applied.

ACGIH
=
American
Conference
of
Governmental
Industrial
Hygienists;
AIHA
=
American
Industrial
Hygiene
Association;
STEL
=
Short
Term
Exposure
Level;
LOAEL
=
Lowest
Observed
Adverse
Effect
Level;
NOAEL
=
No
Observed
Adverse
Effect
Level;
WEEL=
Workplace
Environmental
Exposure
Level;
AEL
=
Acceptable
Exposure
Level;
NA=
Not
Available
September
16,
2003
4
4.
ATMOSPHERIC
MODELING
This
section
presents
an
assessment
of
the
potential
risks
to
atmospheric
integrity
posed
by
the
use
of
SUVA
®
407C
in
the
refrigeration
and
air­
conditioning
sector.
The
ODP,
GWP,
and
ALT
of
the
proposed
substitute
are
presented
in
Table
3.

The
environmental
impacts
resulting
from
use
of
SUVA
®
407C
are
generally
in
the
range
of
those
predicted
for
other
substitutes
examined
in
the
Background
Document,
hence
EPA
believes
that
the
substitute
is
substantially
less
harmful
to
the
ozone
layer
than
the
continued
use
of
CFCs
or
HCFCs.
The
GWP
for
this
blend
is
within
the
range
of
other
SNAP
approved
alternatives
for
the
proposed
end
uses.

TABLE
3.
ODP,
GWP,
AND
ALT
FOR
PROPOSED
REFRIGERATION
AND
AIR
CONDITIONING
SUBSTITUTES
SUBSTITUTE
ODP
100­
Year
GWP
(
relative
to
CO2)
ALT
(
years)

HFC­
32
0
650
6
HFC­
125
0
3,800
32.6
HFC­
134a
0
1,600
13.6
Source:
WMO
1998.

5.
OCCUPATIONAL
EXPOSURE
AND
RISK
SCREENING
ANALYSIS
Occupational
exposure
modeling
was
performed
for
the
components
of
the
proposed
blend
to
ensure
that
use
of
the
blend
does
not
pose
an
unacceptable
risk
to
workers.
The
highest
8­
hour
estimated
exposure
for
HFC­
134a
in
all
proposed
end
uses
for
both
manufacture
and
disposal
was
222.7
ppm.
For
HFC­
125,
the
highest
8­
hour
estimated
exposure
for
all
proposed
end
uses
was
189.3
ppm,
and
for
HFC­
32,
the
highest
8­
hour
estimated
exposure
was
218.4
ppm.
All
of
the
8­
hour
exposure
values
fall
well
below
1,000
ppm,
the
AEL
of
all
three
chemicals,
and
therefore
pose
no
health
risks
in
occupational
settings.

The
highest
15­
minute
estimated
exposure
for
HFC­
134a
in
all
proposed
end
uses
for
both
manufacture
and
disposal
was
1,718
ppm.
For
HFC­
125,
the
highest
15­
minute
estimated
exposure
was
542
ppm,
and,
the
highest
15­
minute
estimated
exposure
for
HFC­
32
was
745
ppm.
The
15­
minute
exposure
values
for
the
three
substitute
components
are
all
well
below
the
STEL
of
3,000
ppm
for
both
manufacture
and
disposal.
September
16,
2003
5
The
analysis
concluded
that
occupational
exposure
to
any
of
the
constituents
in
the
SUVA
®
407C
blend,
HFC­
134a,
HFC­
125,
and
HFC­
32,
is
not
expected
to
pose
unacceptable
risks
to
workers.

6.
GENERAL
POPULATION
EXPOSURE
This
section
screens
potential
risks
to
the
general
population
from
exposure
to
ambient
air
releases
of
the
substitutes
examined
in
this
report.
Releases
occurring
during
use
of
the
refrigerant
in
a
factory
or
small
mechanic
shop
are
examined
in
this
section.
The
methodology
used
for
refrigerant
screening
was
identical
to
the
one
used
in
the
general
population
exposure
analysis
described
in
Chapter
7
of
the
Refrigeration
and
Air
Conditioning
Background
Document.
Although
modeling
results
for
HFC­
32
are
not
available
in
the
Background
Document,
a
thorough
review
of
HCFC
and
HFC
substitutes
by
end
use
is
provided
including
specific
data
for
HFC­
134a
and
HFC­
125
(
EPA
1994).
Table
4
shows
that
for
each
substitute,
all
end
uses
had
exposure
concentrations
at
least
two
orders
of
magnitude
below
the
reference
concentrations,
even
using
conservative
screening
assumptions.
The
RfC
of
HFC­
32
of
24
ppm
is
close
to
the
RfC
of
many
HCFC
and
HFC
substitutes
reviewed
in
the
background
document,
and
the
exposure
concentration
of
HFC­
32
should
also
be
similar
to
these
substitutes.
The
fenceline
exposure
concentrations,
based
on
the
amount
of
CFC
substitute
released
during
manufacture,
installation,
operation,
servicing,
and
disposal,
would
be
similar
for
HFC­
32
and
other
HCFC
and
HFC
substitutes
because
they
are
used
in
the
same
end
uses
and
the
chemicals
have
similar
chemical
and
physical
properties.
These
results
suggest
that
the
highest
exposure
concentration
for
HFC­
32
would
also
be
significantly
lower
than
the
RfC
for
the
compound.
Thus,
releases
of
HFC­
32
along
with
HFC­
125
and
HFC­
134a
(
as
shown
in
Table
4)
during
manufacture,
end
use,
and
disposal,
are
not
expected
to
pose
a
health
risk
to
the
general
population.
September
16,
2003
6
TABLE
4.
REFERENCE
CONCENTRATIONS
FOR
REFRIGERATOR
SUBSTITUTES
IN
COMPARISON
TO
EXPOSURE
CONCENTRATIONS
Substitute
RfC
(
ppm)
Highest
Exposure
Concentration/
RfC
Ratio
Associated
End
Use/
Site
HCFC­
22
14
9.7
E­
03
Central
A/
C
and
Home
Heat
Pumps/
Factory
HCFC­
123
2
1.0
E­
02
High
Pressure
Centrifugal
Chillers/
Factory
HCFC­
124
50
1.1
E­
03
Retail
Food
Stand
Alone/
Factory
HCFC­
141b
20
2.1
E­
04
Low
Pressure
Centrifugal
Chillers/
Factory
HCFC­
142b
10
3.2
E­
03
Refrigerators
and
Freezers/
Factory
HFC­
23
2
8.1
E­
02
Central
A/
C
and
Home
Heat
Pumps/
Factory
HFC­
125
2
4.9
E­
02
Central
A/
C
and
Home
Heat
Pumps/
Factory
HCFC­
134a
20
1.4
E­
03
Central
A/
C
and
Home
Heat
Pumps/
Factory
HFC­
143a
20
6.9
E­
03
Central
A/
C
and
Home
Heat
Pumps/
Factory
HFC­
152a
15
9.5
E­
03
Windows
A/
C
Units/
Salvage
Yard
HFC­
227ea
2
1.1
E­
02
Refrigerators
and
Freezers/
Factory
7.
CONSUMER
OCCUPATIONAL
ANALYSIS
This
section
presents
estimates
of
potential
consumer
exposures
to
alternative
refrigerants
used
in
home
appliances.
An
assessment
of
chronic
exposure
resulting
from
routine
refrigerant
leaks
and
short­
term
exposure
resulting
from
catastrophic
leaks
are
detailed
below.

7.1
Routine
Leaks
The
Background
Document
assessed
risks
to
consumers
from
chronic
exposure
to
leakage
from
home
appliances
(
refrigerators,
freezers,
dehumidifiers,
central
air
conditioners,
home
heat
pumps,
and
window
air
conditioners).
The
potential
noncarcinogenic
risk
to
consumers
from
chronic
exposure
was
assessed
by
comparing
the
modeled
exposure
concentrations
to
the
RfCs
for
each
refrigerant.
September
16,
2003
7
The
results
reported
in
the
Background
Document
indicate
that
chronic
consumer
exposure
concentrations
resulting
from
routine
leakage,
are
well
below
the
RfCs
for
HFC­
134a
(
84
mg/
m3),
HFC­
125
(
10
mg/
m3),
and
HFC­
32
(
51
mg/
m3).
Therefore,
routine
refrigerant
leaks
are
unlikely
to
pose
a
threat
to
consumer
health.

7.2
Catastrophic
leaks
A
risk
screening
analysis
was
also
performed
that
specifically
examined
exposure
concentrations
resulting
from
catastrophic
releases
for
each
of
the
chemical
constituents
of
the
proposed
blend.
This
analysis
was
conducted
because
the
results
of
the
modeling
of
catastrophic
releases
for
all
the
components
of
SUVA
®
407C
for
all
the
proposed
consumer
end­
uses
are
not
available
in
the
Background
Document.
Furthermore,
unlike
the
analysis
presented
in
the
Background
Document,
this
analysis
provided
an
opportunity
to
examine
the
effects
of
diffusivity
on
exposure
concentrations,
as
discussed
below.
Estimates
of
acute/
short­
term
consumer
exposures
resulting
from
catastrophic
leakage
of
refrigerant
from
residential
refrigerators
and
air
conditioners
were
examined.
The
analysis
was
undertaken
to
determine
the
15­
minute
TWA
for
each
component
of
the
blend,
which
was
then
compared
to
the
STEL
and
cardiotoxic
NOAEL
value
to
assess
the
risk
to
consumers.

"
Worst­
case"
initial
scenarios
were
developed
for
each
of
the
equipment
types.
The
first
scenario
involves
a
window
air
conditioning
unit
leak
into
a
bedroom,
where
an
individual
would
spend
time
while
the
refrigerant
was
being
released
(
i.
e.,
sleeping).
The
second
scenario
is
a
central
air
conditioning
unit
leak
into
a
basement.
An
individual
would
enter
the
room
and
close
the
door.

In
the
two
scenarios,
the
leaking
gas
fills
the
volume
of
the
enclosed
room
and
is
essentially
stratified
into
two
distinct
layers.
This
stratification
is
considered
since
the
refrigerant
gases
are
denser
than
air
and
will
settle
in
higher
concentrations
closer
to
the
ground
with
lower
concentrations
achieved
as
the
distance
from
the
floor
increases.
This
distinction
is
important
because
children,
a
particularly
vulnerable
segment
of
the
population,
breathe
air
that
is
closer
to
the
ground.
Furthermore,
a
sleeping
individual,
as
in
the
scenario
involving
a
release
from
a
window
air
conditioning
into
a
bedroom,
is
normally
positioned
to
breathe
air
from
close
to
the
ground.
In
order
to
simulate
the
concentration
gradient
that
will
occur
because
of
the
weight
differential
between
refrigerant
and
air,
it
is
assumed
that
95
percent
of
the
leaked
refrigerant
mixes
evenly
into
the
bottom
0.4
meter
of
the
room,
and
the
rest
of
the
refrigerant
mixes
evenly
in
the
remaining
volume
(
Kataoka
1999).
Exposure
concentrations
for
the
scenarios
were
calculated
using
the
box
model
described
in
the
Background
Document,
which
was
adapted
to
estimate
concentrations
on
a
minute­
by­
minute
basis.

The
chemical
composition
of
the
refrigerant
in
the
form
of
a
weight
percentage
for
each
of
its
components,
the
molecular
weight
of
each
component,
the
dimensions
of
the
enclosed
space
and
the
amount
of
refrigerant
released
(
assumed
to
be
90%
of
the
charge
size)
were
used
to
September
16,
2003
8
calculate
the
concentration
of
released
refrigerant
in
the
enclosed
area.
The
room
size
and
air
conditioning
unit
charge
size
for
each
scenario
are
as
follows:

 
Bedroom
scenario:
The
bedroom
size
was
assumed
to
be
41
m3
(
EPA
1994).
The
charge
size
for
the
window­
mounted
air
conditioning
unit
was
567
g
(
AHAM
1996).

 
Basement
scenario:
The
size
of
the
basement
was
assumed
to
be
102
m3
(
EPA
1994).
The
charge
size
for
the
central
air
conditioning
unit
was
4.5
kg
(
UNEP
TOC
1994).

Refrigerant
concentrations
were
modeled
under
two
air
change
scenarios
believed
to
represent
the
range
of
potential
flow
rates
for
a
home,
assuming
flow
rates
of
2.5
and
4.5
air
changes
per
hour
(
ACH)
(
Sheldon
1989).
Additional
simplifying
assumptions
have
been
made
for
these
calculations.
First,
the
rooms
are
assumed
to
be
empty,
with
no
cabinets,
furniture
or
fixtures.
Second,
there
is
no
applied
air
motion
(
i.
e.,
no
fan
or
motion
of
people).

Consumer
exposure
concentrations
estimated
from
accidental
releases
of
window
air
conditioners
are
below
STEL
and
NOAEL
values.
However,
for
the
central
air
conditioning
systems,
the
consumer
exposure
concentrations
exceed
the
STEL
values
for
HFC­
125,
HFC­
134a,
and
HFC­
32.
For
the
lower
stratum
in
the
basement
scenario,
with
an
air
exchange
rate
of
2.5,
modeled
consumer
exposures
were
up
to
three
times
greater
than
the
STEL
values
for
blend
constituents.
However,
because
accidental
releases
are
one­
time
exposures,
exceedances
of
the
STEL
values
do
not
necessarily
indicate
a
significant
risk
of
harm
to
consumers.
STELs
are
intended
to
serve
as
short­
term
exposure
limits
in
occupational
settings
in
which
workers
are
exposed
to
the
chemical
in
question
on
a
daily
basis;
they
do
not
represent
limits
for
a
single
exposure
in
a
lifetime.
The
effect
of
a
one­
time
exposure
can
be
more
accurately
evaluated
by
comparing
the
exposure
concentration
to
the
cardiotoxicity
NOAEL.
The
15­
minute
TWAs
of
the
refrigerant
blend
components
are
well
below
their
respective
cardiotoxicity
NOAELs
(
see
Tables
5
and
6).
Because
these
CS
values
were
developed
using
epinephrine­
induced
dogs,
they
represent
a
state
of
physiological
sensitivity
that
is
not
indicative
of
the
normal
human
situation.
It
is
noted
that
in
the
absence
of
epinephrine,
the
components
of
SUVA
®
407C
are
incapable
of
inducing
cardiac
sensitization.
Thus,
the
NOAEL
values
are
conservative
upper
limits
for
shortterm
exposure
to
a
consumer.

Additionally,
the
model
used
to
calculate
the
exposure
concentrations
presented
in
Tables
5
and
6
relies
upon
several
conservative
assumptions.
In
an
actual
catastrophic
release,
only
a
portion
of
the
refrigerant
charge
may
be
released,
and
the
ventilation
rates
and
mixing
ratios
may
be
much
higher
than
those
assumed
for
this
analysis.
Moreover,
in
the
event
that
a
highly
unusual
catastrophic
release
does
occur,
it
is
unlikely
that
the
refrigerant
will
leak
into
the
basement,
but
rather
will
leak
outside
at
the
compressor.

Given
the
conservative
nature
of
the
risk
screen
process
and
the
fact
that
the
calculated
5­
minute
TWAs
of
the
refrigerant
blend
components
are
well
below
the
cardiotoxicity
NOAELs,
September
16,
2003
9
EPA
does
not
believe
that
accidental
releases
from
equipment
containing
SUVA
®
407C
would
pose
a
significant
risk
to
consumers.

TABLE
5.
ESTIMATED
LEVELS
OF
SHORT
TERM
CONSUMER
EXPOSURE
FOR
THE
COMPONENTS
OF
SUVA
®
407C
(
WINDOW
UNIT)

Baseline
Flow
Rate
=
4.5
ACH
Baseline
Flow
Rate
=
2.5
ACH
Lower
stratum
Upper
stratum
Lower
stratum
Upper
stratum
Chemical
STEL
(
Short­
term
Exposure)

(
ppm)
Cardiotoxic
NOAEL/
LOAEL
(
ppm)

15­
minute
TWA
(
ppm)
15­
minute
TWA
(
ppm)
15­
minute
TWA
(
ppm)
15­
minute
TWA
(
ppm)

HFC­
32
4,000
300,000
2,559
26
3,328
34
HFC­
125
4,000
75,000
1,205
12
1,567
16
HFC­
134a
4,000
40,000
2,948
30
3,834
40
TABLE
6.
ESTIMATED
LEVELS
OF
SHORT
TERM
CONSUMER
EXPOSURE
FOR
THE
COMPONENTS
OF
SUVA
®
407C
(
CENTRAL
AC)

Baseline
Flow
Rate
=
4.5
ACH
Baseline
Flow
Rate
=
2.5
ACH
Lower
stratum
Upper
stratum
Lower
stratum
Upper
stratum
Chemical
STEL
(
Short­
term
Exposure)

(
ppm)
Cardiotoxic
NOAEL/
LOAEL
(
ppm)
15­
minute
TWA
(
ppm)
15­
minute
TWA
(
ppm)
15­
minute
TWA
(
ppm)
15­
minute
TWA
(
ppm)

HFC­
32
4,000
300,000
5,258
54
10,419
108
HFC­
125
4,000
75,000
2,476
26
4,907
51
HFC­
134a
4,000
40,000
6,059
63
12,005
124
.

7.3
Asphyxiation
The
risk
of
asphyxiation
for
the
chosen
"
worst­
case"
scenarios
was
investigated
for
the
SUVA
®
407C
refrigerant.
This
analysis
does
not
consider
those
conditions
that
are
likely
to
occur
that
would
reduce
the
levels
to
which
individuals
would
be
exposed,
such
as
open
doors
or
windows,
fans
operating,
conditioned
airflow
(
either
heated
or
cooled),
or
even
openings
at
the
September
16,
2003
10
bottom
of
doors
that
allow
air
to
flow
in
and
out.
As
such,
the
assumed
"
worst­
case"
scenario
is
highly
unlikely.

For
the
first
scenario
(
release
from
a
window
unit
in
a
bedroom),
the
corresponding
maximum
charge
necessary
for
16
percent
oxygen
in
the
lower
stratum
is
0.57
kg.
Charge
requirements
to
reach
the
same
effect
in
the
upper
strata
would
be
even
higher
because
of
the
larger
volumes
there.
These
values
are
significantly
larger
than
the
total
charges
in
the
scenarios
and
thus
represent
no
risk
of
asphyxiation
or
impaired
coordination.
For
the
second
scenario
(
release
from
a
central
air
conditioning
unit
in
a
basement),
a
maximum
charge
of
approximately
3.22
kg
R­
407C
would
be
required
to
displace
oxygen
to
16%.
Therefore
the
central
air
conditioning
unit
with
an
assumed
charge
size
of
4.5
kg
fails
the
basement
test.
Although
the
model
indicates
that
this
refrigerant
blend
fails
the
basement
test,
the
conservative
nature
of
the
asphyxiation
model
indicates
that
the
blend
will
not
lead
to
significant
human
health
concerns.
The
model
assumes
that
the
entire
refrigerant
charge
is
released,
and
the
model
does
not
take
into
account
ventilation
or
circulation.
In
an
actual
catastrophic
release,
only
a
portion
of
the
refrigerant
charge
may
be
released,
and
even
marginal
ventilation/
circulation
rates
would
likely
ensure
that
oxygen
concentrations
would
stay
above
the
16%
threshold.
Therefore,
EPA
does
not
believe
that
the
use
of
SUVA
®
407C
in
this
end­
use
poses
a
significant
risk
of
asphyxiation
to
consumers.

8.
FLAMMABILITY
ANALYSIS
It
is
important
to
consider
the
flammability
of
substances
when
investigating
their
acceptability
for
use
as
refrigerants
since
substitutes
that
are
flammable
could
pose
safety
concerns
to
workers.
As
reported
in
the
submission,
SUVA
®
407C
has
been
classified
by
ASHRAE
34
and
Underwriters
Laboratory
as
nonflammable,
and
thus
poses
no
danger
of
flame
propagation.

9.
VOLATILE
ORGANIC
COMPOUND
(
VOC)
ANALYSIS
HFC­
125,
HFC­
134a.,
and
HFC­
32
have
been
exempted
from
listing
as
VOCs
under
CAA
regulations
(
40
CFR
§
51.000).
September
16,
2003
11
REFERENCES
AHAM.
1996.
Household
Appliance
Industry
HFC
Consumption
Assumptions.
Association
of
Home
Appliance
Manufacturers.
Chicago.
June
3,
1996.

American
Industrial
Hygiene
Association.
The
AIHA
1999
Emergency
Response
Planning
Guidelines
and
Workplace
Environmental
Exposure
Level
Guides
Handbook.
American
Industrial
Hygiene
Association.
Fairfax,
VA
1999.

Collins,
M.
A.,
G.
M.
Rusch,
F.
Sato,
P.
M.
Hext
and
R.
J.
Millischer.
1995.
1,1,1,2­
Tetrafluoroethane
repeat
exposure
inhalation
toxicity
in
the
rat,
developmental
toxicity
in
the
rabbit,
and
genotoxicity
in
vitro
and
in
vivo.
Fund.
Appl.
Toxicol.
25:
271­
280.

Dupont
2001.
"
Material
Safety
Data
Sheet;
SUVA
407C."
Available
at:
http://
msds.
dupont.
com/
msds/
pdfs/
EN/
PEN_
09004a2f8000656e.
pdf
EPA.
1993.
IRIS
website.
http://
www.
epa.
gov/
iris/
subst/
0683.
htm.

EPA.
1994.
"
SNAP
Technical
Background
Document:
Risk
Screen
on
the
Use
of
Substitutes
for
Class
I
Ozone­
depleting
Substances:
Refrigeration
and
Air
Conditioning."
Stratospheric
Protection
Division.
March,
1994.

EPA.
1995.
IRIS
website.
http://
www.
epa.
gov/
iris/
subst/
0656.
htm.

Hardy,
C.
J.,
P.
C.
Kiernan,
I.
J.
Sharman,
and
G.
C.
Clark.
1992.
Assessment
of
cardiac
sensitisation
potential
in
dogs.
Comparison
of
HFC
125
and
Halon
13B1.
Huntingdon
Research
Centre.
Report
No.
ALS
11/
920116.

Kataoka.
1999.
"
Allowable
Charge
Limit
of
Flammable
Refrigerants
and
Ventilation
Requirements."
Draft
Proposal.
O.
Kataoka/
Daikin/
Japan,
June,
1999.

National
Research
Council.
Toxicity
of
Alternatives
to
Chlorofluorocarbons:
HFC­
134a
and
HCFC­
123
Subcommittee
to
Review
Toxicity
of
Alternatives
to
Chlorofluorocarbons,
Committee
on
Toxicology,
Board
on
Environmental
Studies
and
Toxicology,
130
pages,
1996.

Programme
for
Alternative
Fluorocarbon
Toxicity
Testing.
(
PAFT).
1996.
Website
http://
www.
afeas.
org/
paft/

Sheldon,
L.
S.,
et
al.
1989.
"
An
Investigation
of
Infiltration
and
Indoor
Air
Quality."
New
York
State
Energy
Research
&
Development
Authority,
Report
90­
11.

UNEP
TOC.
1994.
1994
Report
of
the
UNEP
Refrigeration,
Air
Conditioning
and
Heat
Pumps
Technical
Options
Committee,
1995
Assessment.

WMO
1998.
Scientific
Assessment
of
Ozone
Depletion,
1998.
World
Meteorological
Organization's
Global
Ozone
Research
and
Monitoring
Project.
Table
10­
8.
