Document ID: EPA-HQ-OAR-2003-0118-0238
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2009-09-29T04:00Z

MEMORANDUM

From:		Margaret Sheppard

		Environmental Scientist, EPA/Stratospheric Protection Division (SPD)

To:		Cindy Newberg

		Chief, Alternatives and Emission Reduction Branch

		EPA/SPD

CC:		Docket EPA-HQ-OAR-2003-0118

Subject:	Blends of HFC-245fa and HFC-365mfc for Foam Blowing

Date:		September 17, 2009

Solvay Fluorides has sent us information on blends of HFC-245fa and 

HFC-365mfc for foam blowing.  The company is particularly interested in
these blends for use in spray foams.  This supplements the company’s
earlier submission of HFC-365mfc for use in all foam blowing end uses.

Flammability

The Significant New Alternatives Policy (SNAP) Program has concerns
about the risks of using flammable foam blowing agents in spray foam
applications.  We require safety training information for use of
flammable foam blowing agents used in spray foam.  HFC-365mfc by itself
is slightly flammable.  Thus, for HFC-365mfc, we would require training
specifically for dealing with flammability hazards when blowing spray
foams.  Instead, Solvay Fluorides’ approach to addressing the
potential flammability risk for spray foams is to create blends of
HFC-365mfc with non-flammable compounds to create non-flammable blends. 

According to flammability testing data, blends of HFC-245fa and
HFC-365mfc are non-flammable as long as HFC-245fa makes up at least 5%
of the foam blowing agent mixture.  Typical blends are likely to contain
30 to 70 percent of each agent and would clearly address flammability
concerns.  

Consumer Exposure to Decomposition Products

	It is possible that the blowing agents will decompose and form toxic
decomposition products over time in closed cell rigid foams.  This is a
particular concern in foam blowing end uses for residential foams (e.g.,
spray foam, polystyrene boardstock, rigid polyurethane &
polyisocyanurate boardstock, phenolic board & bunstock, polyolefin). 
The decomposition products may slowly escape from the foam over time,
and so, we consider the potential for consumer exposure.  There also is
a concern with blends, even where we have previously reviewed the
components of the blend separately for use in foam blowing.  

Since its inception, the SNAP program has examined the potential for
toxic decomposition products from blends for residential foams.  In
particular, we look for whether any decomposition products might be
carcinogenic (e.g., formaldehyde, vinylidene chloride) and whether the
concentration of decomposition products is sufficiently high to be of
concern.  The level of concern that we established in the original SNAP
Background Document for Foam Blowing was 2,000 (+ 500) ppm (by weight
relative to the blowing agent).

	According to information from the submitter, the decomposition products
of HFC-365mfc in polyurethane foams and polyol blends include
CF3CH=CFCH3 isomers Z and E and CF2=CH-CF2CH3.  All these decomposition
products are formed through dehydrofluorination.  The highest
concentration of all decomposition products seen was 0.1%, or 1000 ppm,
below the cutoff of 2000 ppm.

	I also examined data from our earlier review on blends of HFC-245fa and
HCFC-22 in foam blowing for similar end uses.  There, we found that the
decomposition products, cis- and trans- HFO-1234ze were also produced
from dehydrofluorination.  The trans-isomer is relatively well-studied
and we are planning to include it on the list of acceptable substitutes
in foam blowing.  The concentrations of those decomposition products
were below the level of concern.

	Given the relatively low concentrations of the decomposition products,
the lack of indication of unusual toxicity or carcinogenicity of one of
the decomposition products, and the lack of obvious carcinogens, the
consumer risks from decomposition products are acceptably low.

Recommendation

We previously found HFC-245fa acceptable in all foam blowing end uses. 
It is probably the most common foam blowing agent for spray foam today
in the U.S.  The blends of HFC-365mfc and HFC-245fa that we have
evaluated would have lower toxicity and less direct impact on climate
than HFC-245fa alone.  The blends are non-ozone depleting and clearly
reduce risk compared to ozone-depleting substances.  Thus, I recommend
that we find blends of HFC-365mfc and HFC-245fa, containing at least 5%
HFC-245fa, acceptable as substitutes for CFCs and HCFCs for foam
blowing.

ATTACHMENT

From Background Document (Risk Screen) for the Foam Blowing Sector
(1994)

DECOMPOSITION PRODUCTS ANALYSIS FOR SHEATHING IN RESIDENTIAL
CONSTRUCTION FOAMS

	CFC-11 has been widely used as a blowing agent in the production of
rigid insulating foam boardstock.  In addition to use as insulation in
commercial buildings, rigid insulating boardstock foams are commonly
used as sheathing in residential construction.  For these types of
closed-cell foam, most of the blowing agent is retained at the time of
manufacture, and is then released gradually over the useful life and
disposal of the product.  Although the blowing agent in the foam
products is released at different rates depending on variables such as
the foam type, the type of blowing agent used and the type of facer used
in construction of the boards, a typical loss rate of the blowing agent
is less than 10 percent of the volume at manufacture over a 30 year
period.

	In approving the alternatives contained in EPA's final rule for rigid
foam insulating boardstock, the Agency analyzed potential toxicity
concerns related to the decomposition products that are formed by the
chemical degradation of the blowing agent during the foaming or are
otherwise present in the foam boards.  Based on the risk analyses
reviewed by the Agency, EPA has concluded that the decomposition
products associated with the approved substitutes do not pose a concern.
 

	In reaching this decision, EPA relied on a risk assessment of
HCFC-141b, a leading replacement candidate.  In particular, EPA
determined an initial concentration of 2,000 parts per million (ppm) (by
weight relative to the blowing agent) of HCFC-141b decomposition
products in the foam corresponds to an estimated risk of 10-6 (one in a
million).

	The basis for the 2,000 ppm risk screen trigger included the following
assumptions, most of which are conservative:

Hazard Identification:  EPA assumed that all of the primary HCFC-141b
decomposition products (HCFC-151a, HCFC-1131a, and vinylidene chloride)
exhibit the same potency as vinylidene chloride.  

Dose-Response Assessment:  EPA derived an inhalation unit risk factor of
5.0 x 10-5 for vinylidene chloride form information in its IRIS
database.  At a risk level of 1 x 10-6, this corresponds to an exposure
level of 0.02 micrograms per cubic meter (0.02 ppb) in air.  

Exposure assessment:  EPA determined exposure levels based on data on
the characteristics of the following:

	(Exposure levels were estimated based on the methodology reported by
ENVIRON Corporation.  Ficks's law was used to calculate the mass of the
decomposition products released from a typical board.  The diffusion
coefficients used in the Fick's law for the decomposition products were
estimated based on experimental studies of the diffusion properties of
CFC-11 and HCFC-141b.  The values used are summarized in the
above-referenced ENVIRON report;

	(For the structure containing the boardstock foam, it was assumed that
61 4 ft x 8 ft boards were used and that it would have an internal
volume of 411 cubic meters.  The air exchange rate was assumed to be 0.2
air changes per hour;

	(Structure residents were assumed to move into the home immediately
after construction and maintain residence for 30 years, occupying the
house 24 hours per day.

	This risk screen methodology will be applicable to additional blowing
agents reviewed under SNAP.  Thus, EPA would consider use of any blowing
agent that results in insulating foam boards that have aggregate initial
concentrations of decomposition products above 2,000 (plus or minus 500)
ppm (by weight relative to the blowing agent) of concern, unless the
manufacturer can demonstrate to the Agency that higher concentration
levels do not pose risks greater than 10-6.  Risks below this level are
considered acceptable in the context of Agency decisionmaking.

	To demonstrate the acceptability of a rigid insulating foam product
that does not meet the 2,000 (+/-500) ppm trigger, a manufacturer may
submit a variety of supporting data, including evidence that the
relevant decomposition products exhibit low toxicity, or that the
product is significantly less permeable than typical insulation
boardstock.

	This trigger also applies to rigid foam products blown with blends of
chemical alternatives.  In this situation, the initial concentration of
the decomposition products associated with all of the constituents of
the blend in the foam boards should not exceed the trigger.  It is
important that the constituents of the blend not be considered
separately because there may be interactions that occur between the
decomposition products of one constituent and those of another that
could be potentially harmful.

     Prepared by ENVIRON Corporation for Allied-Signal, Inc.,
"Assessment of the Potential Risk to Human Health from the Use of
HCFC-141b as a Blowing Agent in the Manufacture of Rigid Insulating
Boards For Use in Home Construction," September 1991. 

     The Agency recognizes that test results may vary slightly due
to sample quality or calibration of instruments.  Therefore, sample
results up to 2,500 ppm (2,000 +/- 500 ppm) are an acceptable
demonstration of no significant risk.

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