Document aBw2wJ8RQa16eaKXe1zb66aQy

Significant New Alternatives Policy Program Fire Extinguishing and Explosion Prevention Sector Risk Screen on Substitutes As a Streaming Agent in Civil Aviation Applications Substitute: 2-bromo-3,3,3-trifluoropropene (2-BTP) 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 two decades, 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 assessment 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 number of substitutes in many end-use applications within all of the major ODSusing 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 report is to supplement EPA's Background Document on the fire extinguishing and explosion protection sector (hereinafter referred to as the Background Document, EPA 1994a). This risk screen discusses the potential human health and environmental risks posed by 2-bromo-3,3,3trifluoropropene (hereinafter referred to as 2-BTP) when used as a streaming agent as a replacement for halon 1211 in civil aviation applications, specifically in handheld extinguishers onboard aircraft. Table 1 details the composition of the proposed substitute prior to activation. Table 1: Composition of 2-BTP and Potential Impurities Component Chemical Formula CAS Number Concentration (Weight Percent) 2-bromo-3,3,3-trifluoropropene CF3CBr=CH2 1514-82-5 >99.5% Potential Impurities (maximum concentration) 1,2-dibromo-3,3,3-trifluoropropane C3H3Br2F3 431-21-0 0.3% 3,3,3-trifluoropropyne C3HF3 661-54-1 0.1% 3,3,3-trifluoropropene C3H3F3 677-21-4 0.1% Section 2 of this report summarizes the results of the risk screen for the proposed substitute for use in normally occupied spaces. The remainder of the report is organized into the following sections: Section 3: Atmospheric Assessment ***** FINAL March 25, 2016 ***** 1  Section 4: Volatile Organic Compound Assessment Section 5: Potential Health Effects Section 6: Discussion of End-Use Scenarios Section 7: Occupational Exposure Assessment Section 8: End-Use Exposure Assessment Section 9: General Population Exposure Assessment Section 10: References 2. SUMMARY OF RESULTS EPA's risk screen indicates that the use of the proposed substitute will be less harmful to the atmosphere than the continued use of halon 1211 and substitutes used in this sector, such as HCFC Blend B and HFC227ea, as it is less harmful to the ozone layer, has lower climate impact, and a shorter atmospheric lifetime. 2-BTP's contributions to volatile organic compound (VOC) emissions are likely to be insignificant compared to VOC emissions from all other sources (i.e., both anthropogenic and biogenic). EPA's risk screen indicates that the use of the proposed substitute is not expected to pose a significant toxicity risk to personnel or the general population, specifically when proper engineering controls are employed during manufacturing activities. It is expected that procedures identified in the material data safety sheet (MSDS) for 2-BTP and good manufacturing practices will be adhered to, and that the appropriate safety and personal protective equipment (PPE) (e.g., protective gloves, tightly sealed goggles, protective work clothing, and suitable respiratory protection in case of accidental release or insufficient ventilation) consistent with OSHA guidelines will be used, as applicable, during manufacture and disposal of 2-BTP streaming fire extinguishing systems. 3. ATMOSPHERIC ASSESSMENT This section presents an assessment of the potential risks to atmospheric integrity posed by the use of 2BTP as a streaming fire extinguishing agent in civil aviation applications. The proposed substitute is substantially less harmful to the ozone layer, has a lower climate impact and a shorter atmospheric lifetime compared to halon 1211. In addition, 2-BTP has a lower climate impact and shorter atmospheric lifetime than those predicted for other substitutes examined in the Background Document, as well as a commonly utilized substitutes. Table 2, below, summarizes the atmospheric impacts of 2-BTP in comparison to other streaming agents, based on model results of the atmospheric transport of surface emissions to the upper troposphere. 2-BTP is under evaluation for use onboard aircraft, in which case it could potentially be released in the atmosphere at higher altitudes in flight (i.e., approximately 9-12 kilometers above ground-level) and therefore have a stronger effect on stratospheric ozone than presented in the table below. However, based on the known frequency of handheld fire extinguisher discharges onboard commercial airplanes, the probability of discharge of 2-BTP from a handheld fire extinguisher in flight is anticipated to be approximately 1.5 x 10-6 per flight; based on reported discharges, 53 percent of those releases are expected to be on actual fires, in which case the agent would react to form byproducts (Boeing 2013). Therefore, the emissions of 2-BTP into the atmosphere at altitude from a handheld extinguisher onboard aircraft is expected to be negligible and have an insignificant impact on stratospheric ozone. Thus, EPA believes that use of 2-BTP would result in substantially less harm to the climate and ozone layer than the continued use of ODS and commonly used ODS substitutes. ***** FINAL March 25, 2016 ***** 2 Table 2: Atmospheric Impacts of 2-BTP Compared to Other Streaming Agents Chemical ODP GWP (100-year) ALT (years) Proposed Substitute 2-BTP 0.0028a 0.23 - 0.26b 7 daysa Other Streaming Agents Halon 1211 7.9c 1,890d 16d HCFC Blend Be 0.019c 367d NAf HFC-227ea 0 3,220d 34.2d a Patten et al. 2012 b GWP range represents GWPs for 30N to 60N and 60S to 60N emissions scenarios for a 100-year time horizon. A tropospherically well- mixed approximation of the GWP is equal to 0.59. (Patten et al. 2012) c WMO (2010) d IPCC 4th Assessment Report (Forster et al. 2007) e HCFC Blend B is a blend consisting of HCFC-123 (>93%), PFC-14 (<4%), and an additional additive. f Atmospheric lifetimes are not given for blends because the components separate in the atmosphere. The ALT for HCFC-123 is 1.3 years and the ALT for PFC-14 is 50,000 years (IPCC 4th Assessment Report [Forster et al. 2007]. 4. VOLATILE ORGANIC COMPOUND (VOC) ANALYSIS 2-BTP is regulated as a VOC under CAA (40 CFR 51.100(s)). Through regulations and standard industry practices, emissions of 2-BTP should be controlled. An assessment was performed to compare the annual VOC emissions from the use of 2-BTP as streaming agent to other anthropogenic sources of VOC emissions. Assuming the submitter's maximum anticipated annual production of 2-BTP for all proposed fire suppression end-uses is entirely released (in the absence of controls), approximately [ ] of VOCs would be emitted. This is approximately equal to [ ] percent of all anthropogenic VOC emissions in the U.S. in 2014;1 however, the release of total production for all proposed end-uses of 2-BTP is extremely unlikely to occur, as this would imply that all installed total flooding systems would be completely discharged in the same year. An additional analysis was performed to determine more realistic annual VOC emissions from the use of 2-BTP in streaming applications. Assuming the average annual release rate for streaming applications of 3.5% is applied to the entire intended U.S. annual production of 2-BTP, approximately [ ] of VOCs would be emitted, which is approximately equal to [ ] percent of all anthropogenic VOC emissions in the United States. Although the VOC emissions for these fire suppression applications are several orders of magnitude lower than other anthropogenic emissions, it is likely that the estimated VOC emissions estimated here can be further reduced. There are acceptable fire suppression agents currently in use that are VOCs (e.g., perfluoroketones), and thus, use of 2-BTP is not expected to increase VOC emissions relative to these other acceptable substitutes. Furthermore, most releases of 2-BTP are expected to be at altitude, not in the lower troposphere, and would contribute less to the VOC burden. As the calculated annual releases of 2-BTP from these analyses are several orders of magnitude smaller than other anthropogenic sources of VOC emissions and because 2-BTP would not result in greater impacts on local air quality than other available options, EPA believes that through the use of regulations and standard industry practices, the environmental impacts of these VOCs are not considered a significant concern. 1 Based on the 2014 annual total VOC emissions for the United States (i.e., approximately 17.13x106 MT) as reported in the National Emissions Inventory (EPA 2015). ***** FINAL March 25, 2016 ***** 3 5. POTENTIAL HEALTH EFFECTS As required for a new chemical, the manufacturer of this agent submitted a Toxic Substance Control Act (TSCA) Premanufacture Notice (PMN) for review by EPA. The PMN, designated as P-14-260, has completed EPA review and the manufacturer is presently subject to requirements contained in a TSCA section 5(e) Consent Order. Other future manufacturers and processors will be subject to a TSCA section 5(a)(2) Significant New Use Rule (SNUR) that is expected to be promulgated in 2016. The requirements of the consent order and SNUR would apply to all commercial manufacturing, processing, distribution in commerce, use and disposal of 2-BTP, unless exempted; the SNUR would have similar or identical requirements to the consent order. The consent order requires use of 2-BTP for aircraft either 1) as a total flooding agent in engine nacelles and APUs on aircraft or 2) as a streaming agent in handheld extinguishers in aircraft. In addition, a manufacturer for this agent is required to maintain workplace airborne concentrations of 2-BTP at or below a specified New Chemical Exposure Limit ("NCEL") of 1 part per million (ppm), verified by exposure monitoring data, otherwise PPE (e.g., respirators) must be provided to workers to prevent inhalation exposure. EPA developed the NCEL for 2-BTP based on review of available toxicity studies (U.S. EPA, 2015b). The NCEL is the maximum 8-hour time weighted average (TWA) at which personnel in an occupational environment can be exposed regularly without adverse effects. The basis of the NCEL is long-term health effects (decreased postnatal survival and increased gestation length), and is not relevant to the acute exposure expected at end-use of the fire suppressant. Per UL 2129, labels for 2-BTP extinguishers will contain the statement, "Do not use in confined spaces less than 896 cubic feet per extinguisher." In these confined spaces, UL's acceptable exposure level is based on a calculation using the complete and instantaneous discharge of a single extinguisher and the Lowest Observable Adverse Effect Level (LOAEL) concentration for the agent based on a cardiac sensitization study. Potential exposures at end-use are anticipated to be once-in-a-lifetime. Therefore, the observed LOAEL of 10,000 ppm, based on the cardiac sensitization assessment provided for 2-BTP (summarized in Appendix A), was used to assess potential health risks from exposure to this proposed substitute at end-use. According to the MSDS, exposure to 2-BTP through ocular or dermal absorption is unlikely to cause irritation, and ingestion is not likely to occur in industrial use. However, the most likely pathway of exposure is through inhalation. Overexposure via inhalation to the proposed substitute may cause central nervous system effects, such as dizziness, confusion, physical incoordination, drowsiness, anesthesia, or unconsciousness. At concentrations of 1.0 percent or higher, the proposed substitute may cause increased sensitivity of the heart to adrenaline which might cause irregular heartbeats and possibly ventricular fibrillation or death. In the case that 2-BTP is inhaled, person(s) should be immediately removed and exposed to fresh air. The MSDS recommends that if breathing is difficult, person(s) should seek medical attention. Short ocular, dermal, or ingestion exposures are not expected to pose a hazard. However, in case of ocular exposure, the MSDS for 2-BTP recommends that person(s) should immediately flush the eyes, including under the eyelids, with fresh water and move to a non-contaminated area. Medical attention should be sought if irritation develops or persists. In the case of dermal exposure to 2-BTP, the MSDS recommends that person(s) should immediately wash the affected area with large amounts of water and remove all contaminated clothing and footwear to avoid irritation. If water is not available, cover the affected area with a clean, soft cloth. Medical attention should be sought if irritation develops or persists. 2-BTP is not likely to be hazardous by ingestion; however, in case of ingestion, the MSDS recommends the person(s) to consult a physician immediately. Do not induce vomiting without medical advice. 2-BTP vapors are heavier than air and cause suffocation by reducing oxygen available for breathing, causing asphyxiation in high concentrations. Such vapors pose a potential hazard if large volumes are trapped in enclosed or low places. If person(s) are exposed to high concentrations, the person(s) will ***** FINAL March 25, 2016 ***** 4 likely not realize that he/she is suffocating, but may experience central nervous system effects, such as drowsiness and dizziness. 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 fire suppressants. The potential health effects of 2-BTP are unlikely to occur when following good industrial hygiene practices and the PPE and engineering control (e.g., ventilation) recommendations outlined in the MSDS for 2-BTP and Sections 7 and 8 of this risk screen. 6. DISCUSSION OF END-USE SCENARIOS 2-BTP is proposed for use as a streaming fire extinguishing agent in civil aviation applications. In accordance with UL 711, Rating and Testing of Fire Extinguishers and the Federal Aviation Administration (FAA) Minimum Performance Standard for Hand-Held Extinguishers (DOT/FAA/AR01/37), testing indicated that 3.75 pounds of 2-BTP can replace 2.5 pounds of halon 1211, resulting in a replacement ratio of approximately 1.5 for handheld applications. Therefore, 2-BTP streaming fire extinguishers in aviation applications are expected to be approximately 1,703 grams, based on a typical 1,135 gram-sized halon 1211 handheld extinguisher. 2-BTP handheld extinguishers must also follow required minimum room volumes established by UL 2129, Halocarbon Clean Agent Fire Extinguishers, when discharged into a confined space. This standard prohibits the exceedance of the cardiotoxic LOAEL for any fire suppressant (i.e., 10,000 ppm or 1.0% for 2-BTP). (American Pacific 2014a) The remainder of this risk screen assesses the potential risk of occupational exposure during manufacture, installation, and servicing of 2-BTP handheld extinguishers and end-use exposure when a 2-BTP handheld extinguisher is discharged. To represent a reasonable worst-case scenario, it was assumed that the full charge of the 2-BTP handheld extinguisher is emitted over the course of one minute into a particular area onboard aircraft within the passenger cabin. Because 2-BTP handheld extinguishers can be installed on a wide range aircraft with varying cabin volumes, the analysis in this risk screen conservatively assumes a potential discharge occurs within the minimum space as required by UL 2129 calculated for 2-BTP (i.e., 25 m3 [896 ft3]) (American Pacific 2014b). For narrow and wide body aircraft, cabin air exchange times range from 10.3 to 37.5 air changes per hour (ACH) (American Pacific 2014a). Aircraft cabin air is highly filtered using high-efficiency particulate air (HEPA) filtration technology and continuously recirculated from the outside air, which significantly reduces contaminant levels (Boeing 2014). In this risk screen, both the minimum and maximum ventilation rates were assessed. Furthermore, this risk screen assumes that a vertical concentration gradient will not occur and the released contaminant will be uniformly distributed throughout the entire volume of space because of the presence of high ventilation rates. This assumption is also consistent with typical physiologically based pharmacokinetic (PBPK) modeling, which determines airborne concentration levels of a uniformly-distributed fire suppressant (i.e., total flooding agents) following discharge. The PBPK model is not typically applied to streaming agents because they are usually denser than air and quickly stratify to the floor (Colton & Poet 2013). However, assuming uniform distribution of the agent will provide a conservative estimation of agent concentrations following discharge. Table 3, below, summarizes the end-use scenario assumptions modeled in this risk screen. ***** FINAL March 25, 2016 ***** 5 Table 3. End-Use Scenario Model Assumptions Parameter Assumptions Discharge Space UL 2129 Minimum Confined Space Size (m3) 25 (896 ft3) Ventilation Rate (air changes per hour) 10.3; 37.5 Fire Suppression Unit Handheld Fire Extinguisher Charge Size (g) 1,703 Length of Release (minutes) 1 Vertical Concentration Gradient No 7. OCCUPATIONAL EXPOSURE ASSESSMENT The potential for personnel exposure to 2-BTP during manufacture, installation, and servicing are examined in this section. To evaluate occupational exposure, EPA has evaluated the risks associated with discharge scenarios which are assumed to occur accidentally and not as the result of a fire. Therefore, the recommendations made in this section shall only apply to accidental releases of the 2-BTP compound. 2-BTP is not expected to pose a risk to workers when the engineering controls and PPE recommendations referenced in the MSDS for this proposed substitute are followed. For operations requiring handling of the substitute, engineering controls should include adequate ventilation systems and enclosed or confined operations to ensure exposure levels to the proposed substitute are below the NCEL. In general, use of appropriate PPE is recommended, specifically respirators during activities in which exposure to the proposed substitute cannot be controlled through other means. If the proposed substitute is handled in enclosed spaces where exposure limits might be exceeded, a self-contained breathing apparatus (SCBA) should be used. When handling a leak in a storage container, protective clothing is recommended as well as vapor-in air detection systems. If the presence of the proposed substitute is detected in the workplace atmosphere, there may be a need to purge the gas from the confined space (e.g., with air, water, or an inert gas followed by air), following by additional testing of the space to ensure the proposed substitute has been removed completely from the atmosphere. Furthermore, gloves (i.e., neoprene, polyvinyl chloride [PVC], or polyvinyl alcohol [PVA]) should be worn when handling equipment containing the proposed substitute for prolonged periods. The combination of appropriate engineering controls and the use of PPE will ensure exposure levels to the proposed substitute are below the NCEL. 7.1. Occupational Exposure during Manufacture As described by the submitter, there is limited exposure to the product during manufacturing. Personnel monitoring data were collected during the process of filling a fire extinguisher inside a filling booth equipped with local exhaust ventilation of [ ]. Air sampling data taken at the extinguisher filling area resulted in a TWA exposure of [ ] (American Pacific 2015). This value takes into account measured exposures inside the fill booth and in the filling area (outside the booth). The fill booth was measured to have an approximate volume of [ ]. The table below summarizes the air sampling results provided by the submitter. Table 4. Occupational Exposure Assessment during Manufacturing Proposed Substitute Ventilation Rate (ACH) TWA Exposure (ppm)a Inside the Booth Filling Area (Outside Booth) Total Exposure NCEL (ppm) 2-BTP [ ] [ ] [ ] [ ] 1 a The operator has exposure inside the booth for 7 percent of the time and 93 percent of the time in the surrounding area. ***** FINAL March 25, 2016 ***** 6 These estimated exposure values provided by the submitter are greater than the occupational NCEL of 1 ppm. To effectively mitigate potential occupational exposure and maintain average exposure levels below the NCEL, the manufacturing space should be equipped with specialized engineering controls and well ventilated with a local exhaust system and low-lying source ventilation. The sampling data provided by the submitter demonstrates that local exhaust ventilation greatly reduces exposure concentration inside the fill both and in the filling area (American Pacific 2015) and as such, additional mechanical ventilation above the values tested [ ] can further control exposure levels to achieve a value of 1 ppm or lower. Testing and monitoring of the workplace atmosphere should be conducted regularly to ensure it has not been contaminated with the proposed substitute or any other airborne workplace hazards. Additionally, an eye wash fountain and quick drench facilities must be close to the production area. Employees responsible for chemical processing should wear the appropriate PPE, such as protective gloves, tightly sealed goggles, protective work clothing, and suitable respiratory protection in case of accidental release or insufficient ventilation. EPA believes if these engineering controls are employed, the appropriate occupational safety guidelines are adhered to, and appropriate PPE is used, significant occupational exposure during manufacture of 2-BTP is not expected to occur. 7.2. Occupational Exposure during Installation and Servicing Exposure to 2-BTP is not likely during installation or servicing of 2-BTP streaming fire extinguishing systems. As indicated by the submitter, the risk of accidental activation of the fire extinguishing system while personnel are present in the protected space is highly unlikely if proper procedures are followed. Proper instructions on system installation and servicing included in manuals for the 2-BTP systems should be adhered to. Protective gloves and tightly sealed goggles should be worn for installation and servicing activities, to protect workers in any event of potential discharge of the proposed substitute, accidental or otherwise. Filling or servicing operations should be performed in well-ventilated areas. If handling the material in poorly ventilated areas, use proper respiratory protection. 8. END-USE EXPOSURE ASSESSMENT This section presents estimates of potential consumer exposures to 2-BTP as a streaming fire extinguishing agent in aviation applications. An exposure analysis was performed to examine potential catastrophic releases release of the proposed substitute under the reasonable worst-case scenario outlined in Section 6. For the end-use exposure assessment scenario, 15-minute and 30-minute TWA exposures for the proposed substitute were calculated using the box model described in the Background Document, which was adapted to estimate concentrations on a minute-by-minute basis. The analysis was undertaken to determine the 15-minute and 30-minute TWA exposures of the proposed substitute following potential release of agent from the handheld extinguisher. These exposures were then compared to the LOAEL for 2-BTP, as presented in Table 5, to assess the risk to end-users. Proposed Substitute 2-BTP Table 5: End-Use Exposure Assessment of 2-BTP Ventilation Rate (ACH) 15-min TWA Exposure (ppm) 30-min TWA Exposure (ppm) 10.3 3,410 37.5 1,000 1,810 500 LOAEL (ppm) 10,000 Based on the results, 2-BTP is not expected to pose significant risk to end-users when used as a streaming fire extinguishing agent in civil aviation applications. The modeled 15-minute and 30-minute exposures for both ventilation rates are significantly lower than the LOAEL of 10,000 ppm for 2-BTP. ***** FINAL March 25, 2016 ***** 7 Furthermore, the submitter performed PBPK modeling for 2-BTP using an EPA-approved model that was developed for halon alternatives used in fire suppression. The results are based on constant concentrations and variable exchange rates in accordance with FAA methods for evaluating exposures onboard aircraft. The 5-minute allowable concentration was determined to be 0.95%, just slightly lower than the 1.0% LOAEL for the agent. This modeling report also contains minimum cabin volume requirements for a 2BTP handheld fire extinguisher onboard unpressurized and pressurized aircraft for varying ventilation rates (Colton & Poet 2013). As indicated by the submitter, the probability of handheld fire extinguisher discharges onboard commercial airplanes is estimated to be 1 x 10-6 per flight, 53% of which were on actual fires where the agent would react with the fire to form byproducts different from 2-BTP (American Pacific 2014a). For inadvertent discharges not involving a fire, 2-BTP vapors are several times denser than air and are expected to stratify quickly, falling to the floor (Colton & Poet 2013). Any airborne agent concentrations within the cabin are not anticipated to reach hazardous exposure levels because of the volume and high ventilation of the cabin (American Pacific 2014a). It is also expected that individuals exposed to a discharge of agent could relocate to safer areas within 5 minutes (e.g., if a fire occurs in a remote location on the plane such as the kitchen or lavatory). Onboard aircraft, standard procedures (FAA AC 120-80) require relocation of passengers to allow both access to the fire and safe extinguishing techniques, which is expected to aid in mitigating exposure. As mentioned in Section 5, per UL 2129, labels for 2-BTP extinguishers will contain the statement, "Do not use in confined spaces less than 896 cubic feet per extinguisher." Furthermore, guidelines for the safe and proper use of handheld extinguishers onboard aircraft can be found in FAA Advisory Circular 2042D, Hand Fire Extinguishers for Use in Aircraft. In the event of a fire onboard aircraft, it is expected that personnel are properly trained to operate a handheld extinguisher containing 2-BTP in the presence of other personnel and passengers, some of which may be sensitive populations. In the event of exposure to 2-BTP, individuals are expected to follow the instructions prescribed in the proposed substitute's MSDS. However, when individuals follow the proper precautionary measures described in Sections 6 and 7 of this risk screen, risk of exposure and irritation will be unlikely. 9. GENERAL POPULATION EXPOSURE 2-BTP is not expected to cause a significant risk to human health in the general population when used as a streaming agent in handheld extinguishers on aircraft. The only general population exposure to 2-BTP anticipated will be during discharge of the handheld extinguishers on aircraft. Should releases during manufacturing operations occur, engineering controls should be used (e.g., carbon absorption scrubbers) to collect and prevent the release of the proposed substitute to the atmosphere. 2-BTP is not listed as a priority pollutant or toxic pollutant under the Clean Water Act. Disposal of 2-BTP extinguishers is subject to local, state, and federal regulations, which ensure that releases of 2-BTP and water contaminated with 2-BTP are not be dumped into sewers, on the ground, or into any body of water, but rather taken to a wastewater treatment facility or disposed of properly. 2-BTP is not considered to be hazardous waste under EPA regulations implementing the Resource Conservation and Recovery Act. Disposal procedures as outlined in the proposed substitute's MSDS and local, state, and federal regulations should be followed. EPA believes that by using proper engineering controls and by following disposal and containment recommendations outlined in the proposed substitute's MSDS, exposure to 2-BTP is not expected to pose a significant toxicity risk to the general population. 10. REFERENCES ACGIH. 2004. The Documentation of the Threshold Limit Values and Biological Exposure Indices. American Conference of Governmental Industrial Hygienists. Available at: www.acgih.org. ***** FINAL March 25, 2016 ***** 8 ACGIH. 2005. Guide to Occupational Exposure Values. American Conference of Governmental Industrial Hygienists. ACGIH. 2006. Threshold Limit Values for Chemical Substances (TLV-CS). Dennis Casserly, TLVCS Committee, University of Houston at Clear Lake. American Conference of Governmental Industrial Hygienists. Available online at: http://www.acgih.org/tlv/03_TLV-CS-Update_AIHce06.pdf. American Pacific Corporation. 2013. 2-BTP for Use as a Fire Suppression Agent. 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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). Errata. In: Climate Change 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.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA. Available online at: http://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-errata.pdf. ***** FINAL March 25, 2016 ***** 9 Institute of Medicine. 2000. Clearing the Air: Asthma and Indoor Air Exposures. Committee on the Assessment of Asthma and Indoor Air. Division of Health Promotion and Disease Prevention. Institute of Medicine National Academy Press. Washington, DC. National Academy of Sciences (NAS). 2007. Acute Exposure Guideline Levels for Selected Airborne Chemicals: Volume 6. 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Correction to "OH reaction rate constant, IR absorption spectrum, ozone depletion potentials and global warming potentials of 2-bromo-3,3,3-trifluoropropene," J. Geophys. Res., 117, D22301. U.S. EPA. 1994a. Risk Screen on the Use of Substitutes for Class I Ozone-Depleting Substances: Fire Suppression and Explosion Protection (Halon Substitutes). Stratospheric Protection Division. March 1994. U.S. EPA. 1994b. Methods for Derivation of Inhalation Reference Concentrations and Application of Inhalation Dosimetry. Environmental Criteria and Assessment Office, Office of Health and Environmental Assessment, Office of Research and Development, U.S. Environmental Protection Agency. EPA/600/8-90/066F. October 1994. U.S. EPA. 2015a. National Emissions Inventory (NEI) Air Pollutant Emissions Trends Data. Accessed 12 March 2015. Updated March 2015. Available at: http://www.epa.gov/ttnchie1/trends/. U.S. EPA. 2015b. EPA Response to Comments Received from the Submitter of TSCA Premanufacture Notice (PMN) P-14-260 Regarding EPA's Risk Assessment and Derivation of the Occupational Exposure Limit for the Chemical Substance Reported in P-14-260. April 20, 2015. U.S. EPA. 2012. Acute Exposure Guidelines (AEGLs) Definitions. Available online at: http://www.epa.gov/oppt/aegl/pubs/define.htm. WHO (World Health Organization). 1998. Concise International Chemical Assessment Document 5 - Limonene. Available online at: http://whqlibdoc.who.int/publications/1998/9241530057.pdf. WMO (World Meteorological Organization). 2011. Scientific Assessment of Ozone Depletion: 2010, Global Ozone Research and Monitoring Project-Report No. 52, 516 pp., Geneva, Switzerland. ***** FINAL March 25, 2016 ***** 10