F inal ( October 14, 2014 ) 1 

## Significant New Alt ernatives Policy Program

Foam Blowing Sector

Risk Screen on Substitutes in Ri gid Polyurethane Appliance Foam; Ri gid Polyurethane Commercial Refrigeration and Sandwich Panels; Rigid Polyurethane & Polyi socyanurate Laminate Boardstock; Rigid Polyurethane Slabstock; Flexible Polyurethane; Integral Skin Polyurethane

Substitute: Methylal (Dimethoxymethane)

This risk screen does not contain Clean Air Act (CAA) Confidential Business Information (CBI) and, therefore, may be disclosed to the p ublic.



### 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 decade, 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, administers the Significant New Alternatives Policy (SNAP) Program, which identifies acceptable and unacceptable substitutes for ODS in specific end

- uses based on ass essment of their health and environmental impacts.
EPA’s decision on the acceptability of a substitute is based 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 nu mber of substitutes in many end

- uses within all of the major ODS

- using sectors, including refrigeration and air conditioning, solvent cleaning, foam blowing, aerosols, fire suppression, adhesives, coatings and inks, and sterilization. The results of these risk screens are presented in a series of Background Documents that are available in EPA's docket.
The purpose of this risk screen is to supplement EPA’s Background Document on the foam blowing

sector (EPA 1994) (hereina fter referred to as the Background Docu ment) . This risk screen evaluates the potential use of methylal (also known as d imethoxymethane) in rigid polyurethane appliance foam ; rigid polyurethane commercial refrigeration and sandwich panels ; ri gid polyurethane & polyisocyanur ate laminate boardstock ; rigid polyurethane slabstock ; flexible polyurethane ; and integral skin polyurethane

. 

### T able 1 prese nts information on the composition of the proposed substitute.F inal ( October 14, 2014 ) 2 Table 1

. Composition of Methylal

Constituent Chemical Formula CAS Number Percent of Total (by weight) a Methylal (Dimethoxymethane) C 3 H 8 O 2 109

- 87

- 5 > 99. 49 %

Potential Impurities (maximum concentration)

a Note that less than 0.5 1 percent of m ethylal is composed of impurities. These impurities are reasonably anticipated to be present when the proposed substitute is manufactured for commercial purposes ; h owever, these impurities are not thought to be present in quantities sufficient to pose a risk to humans or to the environment. The potential risks associated with use of foam blowing agents have been examined at length in the Background Document. The reader is referred to this reference for a detailed discussion of the methodologies used to conduct this risk screen. This risk screen addresses flammability risk and assesses the impact of potential releases of m ethylal on the atmosphere and climate. Occupational exposure was modeled to ensure that manufacture and application of the proposed substitute in the proposed foam blowing end

- uses does not pose unacceptable risk to workers. Lastly, general population exposure modeling was performed to ensure that the prop osed substitute would not pose an unacceptable risk to the population at large.
Section 2 of this report summarizes the results of the risk screen for the proposed substitute listed in Table 1 . The remainder of the report is organized into the following sections:

 Section 3 : Atmospheric Assessment

 Section 4 : Volatile Organic Compound Assessment

 Section 5: Potential Health Effects

 Section 6 : Flammability Assessment

 Section 7 : Occupational Exposure Assessment

 Section 8 : End

- Use Exposure Assessment

 Section 9 : General Population Exposure Assessment

 Section 10 : References



### 2

. SUMMARY OF RESULTS

Methylal is recommended for SNAP approval as a foam blowing agent in the following end

- uses: rigid polyurethane appliance foam; rigid polyurethane commercial refrigeration and sandwich panels; rigid polyurethane & polyisocyanurate laminate boardstock; rigid polyurethane slabstock; flexible polyurethane; and integral skin polyurethane

. EPA's risk screen indicates that the use of the proposed substitute will be l ess harmful to the atmosphere than the continued use of CFC

- 11, HCFC

- 141b, HCFC

142b, and HCFC

- 22 , as well as other commonly used blowing agents

. According to the Material Data Safety Sheet ( MSDS )

, m ethylal is highly flammable

. Therefore, personnel should ensure that the substitute is not exposed to high temperatures, sparks, or open flames, as directed in the substitute’s MSDS during use

. Given that appropriate personal protective equipment (PPE) consistent with Occupational Safety & Health Administration (OSHA) guidelines and engineering controls (e.g., exhaust ventilation, vapor

- in

- air detection systems) will be used during installation, maintenance, and disposal activities, no significant risks to workers or the general population are expected.F inal ( October 14, 2014 ) 3 

### 3. ATMOS PHERIC ASSESSMENT

This section presents an assessment of the potential risks to atmospheric integrity posed by the use of

m ethylal as a foam blowing agent

. The ozone depletion potential (ODP), global warming potential (GWP), and atmospheric lifetime (ALT) of the proposed substitute are presented in Table 2

. As compared to blowing agents used in these end

- uses, such as CFC

- 11 , HCFC

- 141b, HCFC

142b, and HCFC

- 22

, m ethylal is substantially less harmful to the ozone layer

, has less climate impact, and a shorter atmospheric lifetime

. In addition, m ethylal also has lower climate impact and a shorter atmospheric lifetime than those for other substitutes examine d in the Background Document

. Thus, EPA believes that use of m ethylal would result in substantially less harm to the climate and ozone layer than the continued use of ODS and other commonly used foam blowing agents

.

Table 2 . Atmospheric Impacts of Methylal Com pared to CFC

- 11, HCFC

- 141b, H C FC

- 142b , and HCFC

- 22 Refrigerant ODP a GWP b AL T (years) b Methylal 0 2.2 days a CFC

- 11 1 4,750 45 HCFC

- 141b 0. 11 725 9. 3 HCFC

- 142 b 0. 065 2,310 17.9 HCFC

- 22 0.05 5 1,810 12 HFC

- 134a 0 1,430 14 HFC

- 245fa 0 1,030 7.6

a WMO (2011)

b IPCC 4 th Assessment Report (Forster, et al 2007)



### 4

. VOLATILE ORGANIC COMPOUND ASSESSMENT

Methylal is regulated as a volatile organic compound (VOC) under the CAA (40 CFR 51. 1 00 (s) )

. Through regulations and standard industry practices, emissions of m ethylal should be controlled. An assessment was performed to compare the annual VOC emissions from use of m ethylal in the foam blowing end

- uses in one year to other anthropogenic sources of VOC emissions. Assuming the submitter’s maximum annual production of m ethylal for all proposed foam blowing sector end

- uses is entirely released, approximately [ ] MT of VOCs would be emitted. This is approximately equal to [ ] percent of all anthropoge nic VOC emissions from 2013 in the U.S

. ; 1 however, the r elease of total production for all foam blowing end

- uses is extremely unlikely to occur. Thus, an additional analysis was performed to determine likely annual VOC emissions from use of m ethylal in the foam blowing sector. Table 3 summarizes leak estimates and market penetrations from the Vintaging Model for the proposed foam blowing end

- uses.

1 Based on the 2013 annual total VOC emissions for th e U.S. (i.e., approximately 16.1x10 6 MT) as reported in the National Emissions Inventory (EPA 2014).F inal ( October 14, 2014 ) 4 Table 3. Foam Release Rates and Market Penetrations by End

- Use

Foam End

- Use Annual Leak Rate First Year Loss a Disposal Loss Lifetime (yrs) Average Annual

Release Rate b Market

Share PU Rigid

– Commercial Refrigeration 0.25% 6 % 90.25% 15 6 % 1%

PU Rigid

– Slabstock 0.75% 37.5% 51.25% 15 6% 1% PU Rigid

– Appliance 0.25% 3.75% 40 % 14 3% 11% PU Rigid

– Sandwich Panels 0.50% 5.5% 69.5% 50 2% 2%

PU Rigid

– Boardstock 1% 6% 44% 50 1% 66%

Flexible PU

- Slabstock 0% 100% 0% 1 100% 1%
Flexible PU

– Integral Skin 2.5% 95% 0% 2 49% 0%

Source: Vintaging Model (v4.4_ 7

. 29

. 14 ).

a First year losses include losses at manufacture and other production steps that occur prior to end

- use.
b Calculated as (Leak Rate + First Year Loss + Disposal Loss)/Lifetime

Assuming the average annual release rates for each of those end

- uses, and that use of m ethylal is distributed according to existing market share for each proposed foam end

- use , 2 approximatel y 1 MT of VOCs would be expected to be released into the atmosphere per year . This amount is approximately 6.2 x10

- 6 percent of all anthropogenic VOC emissions. In addition, the end

- uses with the greatest annual release rate (e.g., integral skin and flexible polyurethane slabstock) are reasonably expected to occur indoors in a manufacturing or disposal facility, which wo uld have engineering controls in place (e.g., carbon adsorption systems or scrubbers ) such that actual quantities of m ethylal emissions would be less than the quantity calculated in this assessment.

Thus, use of m ethylal would not result in greater impacts on local air quality than other available options. In addition, methylal has a relatively lower Maximum Incremental Reactivity (MIR) (i.e., 0.94) relative to other pentane blowing agents (i.e., pentane [MIR = 1.31], iso pentane [MIR = 1.45], and cyclopentane [MIR = 2.39]), which indicates methylal has a lower potential to produce ozone in the atmosphere compared to other commonly used blowing agents. As the calculated annual releases of methylal from these analyses are se veral orders of magnitude smaller than other anthropogenic sources of VOC emissions and are not significantly different than those for other available foam blowing agents , EPA believes that through the use of standard industry practices, the environmental impacts of these VOCs are not considered a significant concern.



### 5

. POTENTIAL HEALTH EFFECTS

To assess potential health risks from exposure to the propose d substitute in foam blowing applications

, EPA identified the relevant toxicity threshold values for comparison to modeled exposure concentra tions for different scenarios. For the occupational exposure analysis, potential risks from chronic and acute worker exposure were evaluated by comparing exposure concentrations to available occupational exposure lim its. Potential risks of chronic worker exposure were evaluated using workplace guidance

2 The distribution of proposed foam end

- uses is based on EPA’s Vintaging Model and may not necessarily represent the submitter’s intended market share for production of methylal.F inal ( October 14, 2014 ) 5 levels (WGL s ). Risks from potential short

- term consumer exposures were evaluated by comparing exposure concentrations to emergency guidance levels (EGL s ). Table 4 list s the relevant toxicity limits for m ethylal , and is followed by Table 5 , which provides an explanation of each toxicity limit. EPA’s approach for identifying or developing these values is discussed in Chapter 3 of the Background Document.

Table 4

. Exposu re Limits for Methylal

Component WGL (Long

- term Exposure) P pm EGL (Short

- term Exposure)
p pm
Methylal 1,000 a (8

- hour OSHA PEL)

1,000 b ( 8

- hour ACGIH TLV

- TWA ) 1,250 ( 15

- min ACGIH STEL)

a OSHA PEL available at: http://www.cdc.gov/niosh/npg/npgd0396.html

b ACGIH TLV

- TWA available at: https ://www.osha.gov/dts/chemicalsampling/data/CH_251500.html

Table 5

. Explanation of Exposure Limit

- Related Terminology a Organization Definition
OSHA Occupational Safety and Health Administration NIOSH National Institute for Occupational Safety and Health ACGIH American Conference of Governmental Industrial Hygienists Exposure Limit Definition Explanation
Short

- Term Exposure
STEL Short

- Term Exposure Limit A 15

- minute Time Weighted Average ( TWA ) exposure that should not be exceeded at any time during a workday, even if the 8

- hour TWA is within the Threshold Limit Value ( TLV )

– TWA , set by ACGIH.
IDLH Immediately Dangerous to

Life and Health If exposed to this concentration, room occupants are exp ected to be able to escape the room within 30 minutes without experiencing
escape

- impairing or irreversible health effects. Long

- Term Exposure PEL Permissible Exposure Limit This is an 8

- hour time

- weighted average exposure limit set by OSHA. TLV

- TWA Threshold Limit Value

–

Time

- Weighted Average The TWA concentration for a conventional 8

- hour workday and a 40

- hour workweek, to which it is believed that nearly all workers may be repeatedly exposed, day after day, for a working lifetime without adverse e ffect according to ACGIH.

a All information in this table taken from EPA (1994) except where otherwise noted.

According to the MSDS, exposure to m ethylal may be harmful by ocular or dermal absorption, inhalation, or ingestion. If m ethylal is inhaled, ingested, or absorbed through skin or eyes in large amounts, the affected person(s) should adhere to the first aid measures provided in the MSDS. In the case of ocular exposure, t he MSDS for m ethylal recommends that person(s) should immediately flush the eyes with water and obtain emergency medical attention if pain, bli nking, tears or redness persist. In the case of dermal exposure (including hair) , the MSDS for m ethylal recommends that person(s) should immediately wash the affected area with s oap and water and remove all contaminated clothing to avoid irritation. Medical attention should be sought if irritation develops or persists. The MSDS recommends personnel

wear respiratory protection in the form of NIOSH and OSHA approved masks or respira tors to avoid excessive methylal inhalation. I f high concentrations of m ethylal are inhaled , person(s) should be immediately removed and exposed to fresh air. The MSDS recommends that if breathing is difficult, medical attention be so ught. If m ethylal is ingested , the MSDS recommends that person(s) consult a physician immediately. If a large quantity of m ethylal was ingested , the MSDS recommends thatF inal ( October 14, 2014 ) 6 person(s) administer lukewarm water (only if person(s) are completely conscious and alert) in order to induce vomiting

. EPA’s review of the human health impacts of this proposed substitute is contained in the public docket for this decision. These risks and procedures after exposure are similar for other common blowing agents.

EPA’s review of the human health impacts of this proposed substitute is contained in the public docket for this decision. These risks and procedures after exposure are similar for other common foam blowing agents. The potential health effects of methylal can be minimized by followi ng the exposure guidelines and ventilation and PPE recommendations outlined in the MSDS for methylal and this risk screen

.



### 6

. FLAMMABILITY ASSESSMENT

Methylal is flammable when its concentration in air is in the range of 2.2 percent to 19.9 percent by volume (22 ,0 00 ppm to 199 ,0 00 ppm) and is considered to be highly flammable ( OSHA Class IB ) at ambient temperatures and atmospheric pressure in both vapor and liquid form

. Methylal has a flash point of

- 30.5 °C and in the presence of an ignition source (e.g., static electricity, a spark resulting from a closed door, a cigarette, or overheating), an explosion or a fire could occur if the concentration of methylal were to exceed the lower flammability limit (LFL) of 22 ,0 00 ppm ( Holland Applied Technologies , Inc. 2014)

.

[ ] When methylal is sold neat, used as the sole blowing agent

, or combined with equally or more flammable blowing agents such as pentane

, 3 the flammability risk is higher. As a result, containers storing pure methylal should be properly labeled as highly flammable ( OSHA Class IB ) and grounded [ ] to prevent ignition from electrical sparks. Furthermore, all potential sources of ignition should be removed from the areas containing methylal and explosion proof equipment (e.g., pump , agitator, light, heating/cooling) [ ] should be installed in accordance with the MSDS.

EPA recommends personnel follow the proper precautions specified in the substitute’s MSDS

. By removing any sources of ignition from areas containing m ethylal

, ensuring warning and flammable labels are affixed to all methylal containers, and by installing recommended equipment and adhering to the other precautions listed in the proposed substitute’s MSDS, it is unlikely that m ethylal will pose a significant flamm ability risk for use in foam blowing

.



### 7

. OCCUPATIONAL EXPOSURE ASSESSMENT

This section presents estimates of potential occupational exposures to m ethylal , which is anticipated to occur during manufacture of blown f oam . To ensure manufacture and application of m ethylal for the proposed foam blowing end

- uses do not present a risk to workers, occupational exposures were derived from personal and area sampling data provided by the submitter.

According to the submitter, personnel monitoring data during producti on of various foam end

- uses has

3 Methylal is less flammable than commonly used foam blowing agents such as methyl formate, n

- pentane, and isopentane, which are all designated Class I flammable liquids. In addition to a lower flammability risk, methylal also has a lower risk of detonation or explosion compared to pentane. Methylal’s heat of combustion (i.e. 6.1 kcal/g) is almost half of pentane’s (i.e. 11.5 kcal/g), resulting in a lowe r likelihood of explosion in the presence of ignition sources (Holland Applied Technologies, 2014).F inal ( October 14, 2014 ) 7 shown that exposure to methylal would be significantly less than the TLV (i.e., 1,000 ppm). [ ]



### 8

. GENERAL POPULATION EXPOSURE ASSESSMENT

Methylal is not expected to adversely impact human health in the general population during manufacture

or end

- use blowing agent formulations

. Releases of m ethylal into the environment are not expected, because manufacture and foam blowing agent mixing are performed in closed systems and air emissions would be trapped within the vessel or equipment in use. Furthermore, [ ] are formulated in specialized plants. If any significant release of m ethylal were to occur, emissions would likely be trapped in plant scrubbers which collect and prevent the release of the proposed substitute to the atmo sphere. Therefore, EPA believes direct exposure to consumers is not a concern beyond the general population exposure scenario di s cussed below.

8. 1 Chronic Exposure to Methylal during Lifetime Foam

- Blowing Agent Releases There is the potential for chronic general population exposures to foam

- blowing agents during the lifetime of the foam in which they are used, because these agents can slowly leak from the foam over time. As a result, in locations where persons are regula rly present for extended periods, such as a home or apartment, the persons could be exposed to very low levels of m ethylal over time. Based on the foam blowing end

uses proposed for m ethylal , the maximum annual rate of release of m ethylal (i.e., after manu facture and before disposal) is anticipated to be 2.5% (see Table 3 ) , resulting in very minimal exposure concentrations for the general population . Due to the low toxicity of m ethylal and minimal expected release, EPA believes that such exposures do not po se a significant toxicity risk, and thus, m ethylal is not expected to cause a significant impact on human health in the general population when used as a foam blowing agent in the proposed end

- uses. 4

Because the proper safety and disposal precautions, as listed in this section, are followed, m ethylal is not expected to cause a significant threat to the environment and human health in the g eneral population when manufactured or used for rigid polyurethane applia nce foam: rigid polyurethane commercial refrigeration and sandwich panels ; rigid polyurethane & polyisocyanurate laminate boardstock ; rigid polyurethane slabstock ; flexible polyurethane ; and integral skin polyurethane end

- uses.

4 Addition al information would be needed to evaluate the risks of blends of methylal and other foam blowing agents for use in certain ri gid cell residentia l foams . As stated in the final rule, 59 FR 13044, “ [EPA] has determined that because of the potential for formation and emission of decomposition products in rigid closed cell foams, notification and review under SNAP is required for blends of chemical al ternatives in foam end

- uses that encompass residential products where chronic consumer exposure could occur. These end

- uses are: polyurethane rigid laminated boardstock, polystyrene extruded boardstock and billet foams, phenolic foams, and polyolefin foam s. ”F inal ( October 14, 2014 ) 8 

### 9

. REFERENCES

Forster, P., V. Ramaswamy, P. Artaxo, T. Berntsen, R. Betts, D.W. Fahey, J. Haywood, J. Lean, D.C. Lowe, G. Myhre, J. Nganga, R. Prinn, G. Raga, M. Schulz and R. Van Dorland. 2007. Changes in Atmospheric Constituents and in Radiative Forcing. In: Climate C hange 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M.Tignor and H.L. Miller (eds.)]. C ambridge University Press, Cambridge, United Kingdom and New York, NY, USA.

Holland Applied Technologies, Inc. 2014. SNAP Submission. 2014. Significant New Alternatives Policy Program Submission to the United States Environmental Protection Agency, April 2014

.

U.S. EPA 1994. Significant New Alternatives Policy Technical Background Document: Risk Screen on the Use of Substitutes for Class I Ozone

- depleting Substances: F oam

- Blowing Agents

. U.S. Environmental Protection Agency, March 1994.

U.S. EPA 2014 . Volatile Organic Compounds

– National Emissions Inventory (NEI) Air Pollutant Emissions Trends Data and Estimation Procedures . Last updated 17 July 2014 . Accessed 18=7 September 2014 . Available at < http://www.epa.gov/ttnchie1/trends/ >.

WMO (World Met eorological Organization), 2011. Scientific Assessment of Ozone Depletion: 2010

, Global Ozone Research and Monitoring Project

— Report No. 52, 516 pp., Geneva, Switzerlan d, 2011.