Document ID: EPA-HQ-OAR-2003-0118-0146
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2006-06-08T04:00Z

March
29,
2006
1
SIGNIFICANT
NEW
ALTERNATIVES
POLICY
PROGRAM
RISK
SCREEN
ON
SUBSTITUTES
FOR
OZONE­
DEPLETING
SUBSTANCES
FOAM­
BLOWING
SECTOR
Risk
Screen
on
the
use
of
Transcend
®
Additive
Technology
as
a
Blowing
Agent
for
the
Manufacture
of
Rigid
Polyurethane
&
Polyisocyanurate
Laminated
Boardstock;
Rigid
Polyurethane
Appliance,
Spray,
Commercial
Refrigeration,
Sandwich,
Slabstock
and
other
Foams;
Phenolic
Insulation
Board
&
Bunstock;
and
Polyurethane
Extruded
Sheet
This
risk
screen
does
not
contain
Clean
Air
Act
(
CAA)
Confidential
Business
Information
(
CBI)
and,
therefore,
may
be
disclosed
to
the
public.

1.
INTRODUCTION
Ozone­
depleting
substances
(
ODS)
are
being
phased
out
of
production
in
response
to
a
series
of
diplomatic
and
legislative
efforts
that
have
taken
place
over
the
past
few
years,
including
the
Montreal
Protocol
and
the
Clean
Air
Act
Amendments
of
1990.
The
U.
S.
Environmental
Protection
Agency
(
EPA),
as
authorized
by
Section
612
of
the
CAA,
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.
The
results
of
EPA's
screening
assessment
of
potential
human
health
and
environmental
risks
posed
by
substitutes
are
presented
in
the
Background
Document
for
each
sector
(
EPA
1994).
These
documents
are
available
in
EPA's
docket.

EPA's
risk
screen
on
the
use
of
Transcend
®
Additive
Technology
as
a
foam
blowing
agent
is
summarized
in
this
document.
The
proposed
substitute
is
[],
mixed
in
with
water,
an
HFC,
or
a
hydrocarbon
(
see
Table
1).
This
risk
screen
only
considers
those
blends
containing
HFCs
and
HCs
which
have
already
been
approved
for
use
in
foam
blowing
agents.
These
approved
HFCs
that
will
be
blended
with
the
Transcend
®
Additive
Technology
foam
blowing
agent
are
HFC­
245fa,
HFC­
134a1
and
the
approved
HCs
are
saturated
light
hydrocarbons
and
Exxsol.
2
As
such,
the
toxicity
and
atmospheric
integrity
of
the
previously
approved
component
of
the
foam
blowing
blend
will
not
be
reviewed
again
in
this
risk
screen
nor
will
any
hazards
associated
with
the
water,
hydrocarbon,
or
HFC
components.
This
risk
screen
deals,
therefore,
exclusively
with
risk
associated
with
the
Transcend
®
Additive
Technology
foam
blowing
agent.
The
reader
is
referred
to
the
Background
Document
for
the
methodologies
and
assumptions
used
to
conduct
the
risk
screen.

Section
2
of
this
report
summarizes
the
results
of
the
risk
screen
for
the
submitted
blowing
agent.
Section
3
presents
the
results
of
the
atmospheric
assessment;
Sections
4
through
7
discuss
occupational,
flammability,
consumer,
and
general
population
exposure
and
risk,
respectively;

1
HFC­
152a
has
also
been
approved
for
use
in
certain
foam
blowing
applications;
however,
Arkema
has
not
applied
for
use
of
HFC­
152a
with
the
Transcend
®
Additive
Technology
foam
blowing
agent.
(
Arkema
2004b)
2
Arkema
has
not
applied
for
the
use
of
hydrocarbon
and
Transcend
®
Additive
Technology
foam
blowing
agent
blends
in
spray
foam
applications.
Therefore,
this
risk
screen
considers
hydrocarbon
and
Transcend
®
Additive
Technology
foam
blowing
agent
blends
for
all
of
the
foam
applications
listed
above
except
for
spray
foams.
(
Arkema
2004b)
March
29,
2006
2
and
Section
8
discusses
potential
increases
in
atmospheric
releases
of
volatile
organic
compounds
(
VOCs).

Table
1:
Substitutes
and
Composition
of
Transcend
®
Additive
Technology
Constituent
Chemical
Formula
CAS
No.
%
of
Total
by
Weight
Transcend
®
Additive
Technology
Foam
Blowing
Agent
H2O,
HFC,
or
HCa
NA
NA
a
The
Transcend
®
Additive
Technology
foam
blowing
agent
may
be
mixed
with
water
or
a
variety
of
HFCs
or
hydrocarbons.
This
risk
screen
will
only
evaluate
blends
which
contain
HFCs
or
hydrocarbons
which
have
already
been
approved
for
use
in
foam
applications.
Therefore,
the
blends
may
contain
H2O,
HFC­
245fa,
HFC­
134a,
saturated
light
hydrocarbons,
or
Exxsol.

Table
2:
Impurities
in
the
Foam
Blowing
Agent
in
ppm*

Chemical
Name
Chemical
Formula
CAS
No.
%
of
Total
by
Weight
of
the
Foam
Blowing
Agent
*
Note:
The
concentrations
were
provided
by
the
submitter
in
ppm
of
the
Transcend
®
Additive
Technology
foam
blowing
agent.
This
concentration
was
scaled
to
the
concentration
in
the
foam
blowing
agent
by
dividing
by
[],
given
that
the
blowing
agent
can
be
up
to
[]%
Transcend
®
Additive
Technology
foam
blowing
agent.
These
concentrations
are
representative
of
a
typical
analysis
of
the
contaminants
in
the
foam
blowing
agent.
However,
as
noted
in
their
submission,
[]
may
represent
up
to
a
maximum
of
[]%
of
the
Transcend
®
Additive
Technology
foam
blowing
agent
component
and
hydrocarbons
may
represent
up
to
[]%
of
the
Transcend
®
Additive
Technology
foam
blowing
agent
component.
These
concentrations
correspond
to
[]
ppm
and
[]
ppm,
respectively.

Table
3:
Byproducts/
Decomposition
Products
Produced
During
Production
of
Finished
Foam
Chemical
Name
Concentration
in
Finished
Foam
(
ppm)

(
Arkema
submission
2004,
page
7
and
Attachment
#
2,
Arkema
Customer
Letter)

2.
SUMMARY
OF
RESULTS
Transcend
®
Additive
Technology
is
recommended
for
SNAP
approval
as
a
foam
blowing
agent.
This
foam
blowing
agent
is
not
expected
to
pose
a
threat
to
atmospheric
integrity,
workers,
consumers,
or
the
health
of
the
general
population.
The
toxicity
and
atmospheric
integrity
of
the
previously
approved
components
of
the
foam
blowing
blend
were
not
reviewed
again
in
this
risk
screen;
therefore,
the
risk
screen
deals
exclusively
with
risks
associated
with
the
Transcend
®
March
29,
2006
3
Additive
Technology
foam
blowing
agent.
The
Transcend
®
Additive
Technology
foam
blowing
agent
has
a
relatively
short
atmospheric
lifetime
of
less
than
a
month.
For
this
reason,
it
is
believed
that
the
compound
is
short­
lived
and
will
not
contribute
significantly
to
stratospheric
ozone
depletion
or
global
warming.
The
Transcend
®
Additive
Technology
foam
blowing
agent
in
the
blends
proposed
poses
low
workplace
flammability
and
explosivity
risks
assuming
good
industrial
hygiene
and
handling
practices
are
used.
The
worker,
consumer,
and
general
exposure
calculations
indicate
no
levels
of
concern.
Finally,
the
Transcend
®
Additive
Technology
foam
blowing
agent
is
a
VOC
and
must
be
controlled
as
such
under
Title
I
of
the
Clean
Air
Act.

3.
ATMOSPHERICS
MODELING
This
section
presents
an
assessment
of
the
potential
risks
to
atmospheric
integrity
posed
by
the
use
of
Transcend
®
Additive
Technology
as
a
foam
blowing
agent.
Although
the
Transcend
®
Additive
Technology
foam
blowing
agent
contains
chlorine,
it
has
a
relatively
short
atmospheric
lifetime
of
less
than
a
month.
For
this
reason,
it
is
believed
that
the
compound
is
short­
lived
and
will
not
contribute
significantly
to
stratospheric
ozone
depletion
or
global
warming.
Because
the
materials
blended
with
the
Transcend
®
Additive
Technology
foam
blowing
agent
to
form
the
blowing
agent
(
i.
e.,
H2O,
HFC­
245fa,
HFC­
134a,
saturated
light
hydrocarbons,
and
Exxsol)
have
already
been
approved
under
the
SNAP
program,
this
risk
screen
does
not
address
the
atmospheric
risks
associated
with
these
components.

4.
OCCUPATIONAL
EXPOSURE
AND
HAZARD
ANALYSIS
This
section
presents
estimates
of
potential
occupational
exposures
to
foam
blowing
agents
during
the
manufacture
of
polyurethane
foams
with
Transcend
®
Additive
Technology.
Because
H2O,
HFC­
245fa,
HFC­
134a,
saturated
light
hydrocarbons,
and
Exxsol
have
already
been
approved
under
the
SNAP
program,
this
analysis
does
not
consider
the
occupational
exposure
to
these
components
of
the
foam
blowing
blend.

The
methodology
utilized
for
this
screening
assessment
is
two­
fold.
The
first
approach
is
identical
to
the
one
used
in
the
occupational
exposure
and
hazard
analysis
as
described
in
Chapter
5
of
the
Background
Document
(
U.
S.
EPA
1994).
As
discussed
in
the
Background
Document,
EPA
did
not
identify
any
information
that
specifically
described
employee
exposures
or
current
workplace
conditions
that
affect
exposure
to
foam­
blowing
agents
used
in
the
production
of
foam
types
other
than
polyisocyanurate
foams.
However,
EPA
stated
in
the
Background
Document
that
employee
exposures
to
blowing
agents
for
other
types
of
foam,
such
as
polyurethane,
generally
can
be
maintained
below
the
AELs
of
all
substitutes
when
adequate
ventilation
and
safe
work
practices
are
employed.
Given
the
similarities
between
foam
types
in
terms
of
manufacturing,
EPA
believes
the
employee
exposure
to
the
Transcend
®
Additive
Technology
foam
blowing
agent
can
be
maintained
below
its
AEL.

The
second
approach
is
based
on
a
simple
box
model
calculation
to
estimate
potential
occupational
exposure
based
on
typical
foam
blowing
manufacturing
characteristics
(
e.
g.,
blowing
agent
formulation,
release
rate,
and
ventilation).
Utilizing
a
theoretical
polyurethane
appliance
foam
manufacturing
scenario,
modeled
worker
exposure
to
the
Transcend
®
Additive
Technology
foam
blowing
agent
and
selected
byproducts/
impurities
is
estimated
to
be
well
below
the
AEL
when
adequate
ventilation
is
present.
Please
see
Attachment
A
for
details
on
the
box
model
analysis.
March
29,
2006
4
Finally,
it
is
believed
that
Transcend
®
Additive
Technology
can
be
safely
used
as
a
foam
blowing
agent
as
long
as
appropriate
work
practices
are
employed.
These
would
include
adequate
general
ventilation
within
the
workspace,
the
use
of
local
ventilation
(
fume
hoods)
wherever
possible,
conscious
use
of
personal
protective
equipment
(
PPE),
and
comprehensive
workplace
safety
procedures
and
training.

5.
EXPLOSIVITY
AND
FLAMMABILITY
The
Transcend
®
Additive
Technology
foam
blowing
agent
is
both
flammable
and
explosive
above
certain
concentrations.
However,
testing
by
Arkema
shows
that
when
the
Transcend
®
Additive
Technology
foam
blowing
agent
is
mixed
with
at
least
[],
the
mixture
is
not
flammable.
Similar
testing
showed
that
when
the
Transcend
®
Additive
Technology
foam
blowing
agent
is
mixed
with
more
than
[],
the
mixture
is
not
flammable.
Therefore,
use
of
the
proposed
mixture
of
[]
Transcend
®
Additive
Technology
foam
blowing
agent
and
[]
is
considered
safe.
[].
Therefore,
it
is
important
that
all
manufacturers
using
Transcend
®
Additive
Technology
have
a
safety
plan
in
place
addressing
the
potential
flammability
of
the
foam
blowing
agent.

Saturated
light
hydrocarbons
and
Exxsol
are
flammable
and
have
already
been
approved
under
the
SNAP
program.
Therefore,
these
approved
hydrocarbon
and
Transcend
®
Additive
Technology
foam
blowing
agent
blends
are
also
considered
safe
as
long
as
workers
follow
the
safety
plans
and
procedures
required
when
using
approved
hydrocarbon
foam
blowing
agents.
The
Transcend
®
Additive
Technology
submission
did
not
apply
for
the
use
of
hydrocarbons
in
spray
foam
blends;
therefore,
hydrocarbon
blends
in
spray
foam
applications
are
not
covered
by
this
risk
screen.
Furthermore,
a
flammability
safety
program
does
not
currently
exist
for
saturated
light
hydrocarbons;
therefore,
these
saturated
light
hydrocarbons
have
not
been
previously
approved
for
use
in
spray
foam
applications.

6.
CONSUMER
EXPOSURE
Each
of
the
foam
application
types
where
this
agent
will
be
used
typically
retains
a
portion
of
the
blowing
agent
within
the
foam
cells
that
is
slowly
released
over
time
into
the
area
where
the
foam
products
are
installed.
However,
given
the
very
small
amounts
and
significant
dilution
likely
to
occur
with
ambient
air,
the
release
of
residual
blowing
agent
(
and
its
byproducts)
is
not
expected
to
cause
any
hazard
to
the
consumer.
This
approximation
is
also
based
on
the
EPA's
threshold
risk
level
of
10­
6
(
one
in
a
million)
associated
with
initial
foam
byproduct
concentrations
of
2,000
ppm
+/­
500
ppm
as
the
risk
screen
trigger
noted
in
Attachment
6­
A
of
the
Background
Document.
The
only
byproduct
detected
in
the
finished
foam
cells
resulting
from
the
breakdown
of
the
Transcend
®
Additive
Technology
foam
blowing
agent
is
[].
The
concentrations
of
[]
are
well
below
the
levels
of
concern
(
Table
4).

Table
4:
Decomposition
Products
Produced
in
the
Cells
of
the
Finished
Foam
Chemical
Concentration
in
Finished
Foam
(
ppm)*

*
The
[]
decomposition
products
in
the
finished
cell
are
at
concentrations
of
[]
ppm
of
the
foam
gas
or
[]
(
by
weight)
of
the
total
foam.
Note:
This
testing
was
done
with
HCs
instead
of
HFCs.
However,
it
is
believed
that
the
presence
of
an
HFC
will
not
affect
the
breakdown
of
the
foam
blowing
agent
(
Arkema
2004a
and
Shankland
2005).
March
29,
2006
5
Because
H2O,
HFC­
245fa,
HFC­
134a,
saturated
light
hydrocarbons,
and
Exxsol
have
already
been
approved
under
the
SNAP
program,
this
analysis
does
not
consider
the
consumer
exposure
to
the
HFC
or
HC
component
of
the
foam
blowing
blend.

7.
GENERAL
POPULATION
EXPOSURE
AND
RISK
SCREENING
ANALYSIS
The
general
population
exposure
to
the
Transcend
®
Additive
Technology
foam
blowing
agent
resulting
from
its
manufacture
or
use
is
not
expected
to
cause
any
significant
threats
to
human
health.
The
fence
line
concentration
during
processing
of
products
containing
HCFCs
and
HFCs
has
been
determined
for
manufacturing
settings
for
fire
protection
devices
and
refrigerants,
but
not
specifically
for
foam
blowing
applications.
The
volume
of
the
Transcend
®
Additive
Technology
foam
blowing
agent
is
expected
to
be
smaller
than
the
amount
of
refrigerant
typically
released
in
the
analyses
in
the
Background
Document.
Therefore,
by
analogy
to
these
other
fence
line
analyses
that
have
been
performed,
in
which
concentrations
were
more
than
two
orders
of
magnitudes
below
the
reported
reference
concentrations
(
even
utilizing
conservative
screening
assumptions),
it
is
not
expected
that
foam
blowing
applications
will
pose
health
risks
to
the
general
population.

8.
VOLATILE
ORGANIC
COMPOUND
ANALYSIS
H2O
and
HFCs
are
expected
to
pose
negligible
concerns
in
terms
of
their
contribution
to
photochemical
smog.
They
are
not
considered
to
be
volatile
organic
compounds
(
VOCs)
and
are
unreactive
in
the
troposphere.
However,
hydrocarbons
and
the
Transcend
®
Additive
Technology
foam
blowing
agent
are
VOCs
and
must
be
controlled
as
such
under
Title
I
of
the
Clean
Air
Act.

9.
REFERENCES
Arkema.
2004a.
"[]".
Memo
to
Tom
Werkema
from
Jinhuang
Wu
on
November
23,
2004.

Arkema.
2004b.
Transcend
®
Additive
Technology
SNAP
Petition.
Memo
to
U.
S.
EPA
from
Tom
Werkema
of
of
Arkema
on
December
22,
2004.

Arkema
Submission.
2004.
Submission
for
Transcend
®
Additive
Technology.
Submitted
on
November
5,
2004.

Shankland,
Ian.
2005.
Personal
e­
mail
communication
with
ICF
Consulting,
7
January
2005.

U.
S.
EPA.
1994.
Risk
Screen
on
the
Use
of
Substitutes
for
Class
I
Ozone­
Depleting
Substances:
Foam
Blowing
Agents).
Stratospheric
Protection
Division.
March
1994.
March
29,
2006
6
ATTACHMENT
A:
OCCUPATIONAL
EXPOSURE
ASSESSMENT
FOR
TRANSCEND
®
ADDITIVE
TECHNOLOGY
1.
INTRODUCTION/
EXPOSURE
SETTING
Transcend
®
Additive
Technology
can
be
used
as
an
alternative
to
ozone
depleting
foam
blowing
agents
in
multiple
applications.
In
this
case,
Transcend
®
Additive
Technology
is
used
as
a
coblowing
agent
with
HFC­
245fa
([]
ratio).
While
it
is
possible
that
Transcend
®
Additive
Technology
may
eventually
also
be
used
in
other
applications,
this
document
attempts
to
provide
a
brief
assessment
of
exposures
in
only
the
foam
manufacturing
application.

In
order
to
assess
exposures
for
the
foam
blowing
end
use,
an
application
scenario
must
be
developed.
For
example,
Transcend
®
Additive
Technology
could
be
used
in
manufacturing
commercial
refrigeration
panels,
which
is
typically
performed
within
a
ventilated
foaming
booth,
or
in
manufacturing
polyurethane
(
PU)
slabstock
or
boardstock,
which
is
performed
on
the
large
well­
ventilated
factory
floor
with
supplemental
local
ventilation
hoods
in
some
cases.
In
a
typical
manufacturing
setting,
a
worker
would
be
exposed
to
Transcend
®
Additive
Technology
on
a
relatively
continuous
basis
over
an
8­
hour
workday.

Exposure
levels
depend
on
multiple
factors
including
the
ventilation
in
the
room,
the
size
of
the
room,
the
amount
of
blowing
agent
being
used,
and
the
proximity
of
the
spray
nozzle/
gun
to
the
user.
Residual
vapors
from
spraying
would
be
present
in
the
work
area
throughout
the
production
process.
Since
the
chemical
would
typically
be
utilized
over
an
8­
hour
workday,
this
assessment
focuses
on
the
long­
term
term
occupational
exposure
to
Transcend
®
Additive
Technology
as
a
result
of
inhalation.
Impurity
or
degradation
products,
[]
and
[],
have
high
toxicity
and
a
very
low
exposure
limits;
thus
this
assessment
evaluates
the
potential
occupational
exposure
to
these
compounds
as
well.
Other
impurities
and
byproducts
were
not
considered
due
to
very
low
concentrations
and/
or
higher
safe
exposure
limits.
Potential
impacts
from
catastrophic
exposure
levels,
such
as
those
that
could
occur
from
an
accident
or
spill,
are
not
assessed
in
this
study.

Section
2
presents
the
results
of
the
analysis;
Section
3
presents
the
results;
and
Section
4
lists
references
used
to
create
this
analysis.

2.
APPROACH
The
approach
for
assessing
occupational
exposure
to
Transcend
®
Additive
Technology
was
to
model
the
use
of
foam
blowing
agent.
A
box
model
approach
will
be
utilized
to
estimate
blowing
agent
occupational
exposure
from
the
manufacture
of
foam
material.
The
box
model
determines
the
average
concentration
of
a
gas
in
a
workspace
by
utilizing
gas
emission
and
site
characteristics
and
has
been
widely
used
for
many
years
(
EPA
1991).
The
box
model
analysis
will
augment
the
existing
exposure
monitoring
data
(
i.
e.,
polyurethane
boardstock,
appliance
foam,
and
any
additional
studies)
contained
within
the
Background
Document.
March
29,
2006
7
Box
Model
Equation:

Ca
=
((
Yv
*
24,440)
/
((
AT
*
k)*
MW))

Where:
Ca
=
Concentration
of
the
blowing
agent
in
air
(
ppm)
Yv
=
Mass
emission
rate
of
volatile
compound
release
(
g/
sec)
AT
=
Air
flow
rate
(
m3/
sec)
k
=
Mixing
coefficient
(
0.5,
EPA,
1991)
MW
=
Molecular
weight
of
the
blowing
agent
(
g/
mole)
24,440
=
Conversion
factor
for
g/
m3
to
ppm
The
concentration
of
the
blowing
agent
in
air
will
then
be
compared
with
reported
occupational
exposure
limits
for
that
agent.
Of
these
values,
AT
or
air
flow
rate
is
an
important
driver
of
exposure
and
also
the
variable
most
likely
to
be
the
basis
of
mitigation
actions
taken
to
reduce
occupational
exposure.
The
k­
value
represents
the
overall
mixing
of
air
in
the
workplace,
with
a
value
of
1
representing
complete
mixing,
and
a
value
approaching
zero
representing
unmixed
or
stagnant
air
around
the
exposure
site.

Modeling
was
based
upon
commercial
appliance
foam
blowing
manufacturing
scenarios
described
in
Chapter
5
of
the
Background
Document
combined
with
a
manufacturing
agent
release
rate
for
PU
slabstock
foams.
3
In
this
section
the
assumptions
and
application
scenarios
used
to
create
the
exposure
model
are
described.

Assumptions:

 
Foam
production
is
60
and
90
pound
of
foam
per
hour
under
moderate
and
high
use,
respectively;
 
Foaming
booth
size
is
10
feet
by
10
feet
by
10
feet;
 
Ventilation
rate
is
33
and
66
cubic
meters
per
minute
under
low
and
moderate
conditions,
respectively
(
EPA
1994);
 
The
blowing
agent
formula
consists
of
[]
percent
Transcend
®
Additive
Technology
foam
blowing
agent
and
[]
percent
HFC­
245fa,
with
[]
ppm
[]
and
[]
ppm
[]
as
byproducts/
impurities
(
Arkema
2004);
 
Blowing
agent
content
is
12
percent
(
EPA
2001);
and
 
Percent
of
agent
released
at
manufacturing
is
37.5
percent
(
PU
slabstock
foams)
(
EPA
2001).

3.
RESULTS
The
use
scenarios
were
modeled
in
both
average
and
poor
ventilation
settings
for
the
Transcend
®
Additive
Technology
foam
blowing
agent,
[],
and
[].
The
results
of
the
analysis
are
outlined
in
Tables
1
and
2.

3
Please
note
that
the
manufacturing
release
rate
of
commercial
appliance
manufacturing
foams
is
typically
around
6
percent.
In
this
case,
the
release
rate
for
PU
slabstock
(
37.5
percent)
is
utilized
to
simulate
a
"
high
release"
scenario.
March
29,
2006
8
Table
1:
Eight­
Hour
Transcend
®
Additive
Technology
Foam
Blowing
Agent
Exposure
Concentrations
Low
Ventilation
(
ppm)
Moderate
Ventilation
(
ppm)
AEL
(
ppm)
Moderate
Use
77.7
38.8
High
Use
116.5
58.3
Table
2:
Eight­
Hour
[]
Exposure
Concentrations
Low
Ventilation
(
ppm)
Moderate
Ventilation
(
ppm)
Exposure
Limita
(
ppm)
Moderate
Use
0.04
0.02
High
Use
0.06
0.03
Note:
Because
[]
is
highly
reactive
in
air,
actual
exposure
is
likely
to
be
significantly
less
than
the
values
reported
in
this
table.
a
Ceiling
limit
for
[]
as
a
proxy.

Table
3:
Eight­
Hour
[]
Exposure
Concentrations
Low
Ventilation
(
ppm)
Moderate
Ventilation
(
ppm)
AEL
(
ppm)
Moderate
Use
0.002
0.001
High
Use
0.004
0.002
The
exposure
concentration
for
Transcend
®
Additive
Technology
in
each
of
the
scenarios
modeled
is
significantly
lower
than
the
recommended
8­
hour
AEL.
Even
in
occupational
settings
where
there
may
be
high
use
and
poor
ventilation,
the
modeled
8­
hour
concentration
is
approximately
half
the
recommended
AEL.
The
exposure
concentration
for
associated
impurities
and
byproducts
of
Transcend
®
Additive
Technology,
particularly
[]
and
[],
are
significantly
lower
than
the
recommended
8­
hour
AEL
of
[]
ppm
for
[]
and
the
[]
ppm
Ceiling
level
for
[].
It
should
be
noted
that
the
exposure
levels
for
each
of
the
compounds
analyzed
were
below
exposure
limits
even
under
the
theoretical
high­
use
and
low­
ventilation
"
worst­
case"
exposure
scenario.
Therefore,
modeling
results
suggest
that
occupational
exposure
from
the
use
of
Transcend
®
Additive
Technology
does
not
pose
a
threat
to
workers'
health,
assuming
adequate
ventilation
is
present.

4.
REFERENCES
Arkema.
2004.
[]
­
Memorandum.
December,
2004.

U.
S.
EPA.
2001.
U.
S.
High
GWP
Gas
Emissions
1990­
2010:
Inventories,
Projections,
and
Opportunities
for
Reductions.
Office
of
Air
and
Radiation.
June
2001.

U.
S.
EPA.
1994.
SNAP
Technical
background
Document:
Foam
Blowing
Agents.
Office
of
Air
and
Radiation.
March
1994.

U.
S.
EPA.
1991.
Building
Air
Quality,
Revised.
EPA­
402­
F­
91­
102.
EPA
Office
of
Indoor
Air.
December
1991.