Document ID: EPA-HQ-OAR-2011-0111-0021
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2012-09-19T04:00Z

Significant New Alternatives Policy Program
Fire Extinguishing and Explosion Prevention Sector

Risk Screen on Substitutes for Halon 1301
Total Flooding Systems in Normally Unoccupied Spaces

                                Substitute: KSA

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

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 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 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 fire suppression and explosion protection sector (EPA 1994a) (hereinafter referred to as the Background Document). This risk screen discusses potential human health and environmental risks posed by KSA when used as a flooding agent in normally unoccupied spaces as a replacement for Halon 1301. Table 1 provides the composition of KSA prior to and after activation and Table 2 provides the maximum concentrations of impurities found in KSA.

Table 1:  Composition of KSA, Pre- and Post Activation
                                  Constituent
                               Chemical Formula
                                     CAS #
                                Weight Percent
                                                                               
                                       
               
Table 2:  Maximum Concentrations of Impurities in KSA
                                   Impurity
                               Chemical Formula
                             Maximum Concentration
                                                                               

               
Section 2 of this risk screen summarizes the results of the risk screen for the proposed substitute.  The remainder of the risk screen is organized into the following sections:

   * Section 3: Atmospheric Assessment; 
   * Section 4: Occupational Exposure Assessment;
   * Section 5: General Population Exposure Assessment; 
   * Section 6: Volatile Organic Compound Assessment; and
   * Section 7: References.
      
SUMMARY OF RESULTS
KSA is recommended for SNAP approval as a flooding agent in normally unoccupied spaces.  Given that proper training will be provided to personnel and that appropriate personal protective equipment (PPE) and proper procedures according to the MSDS will be used during manufacturing, installation, maintenance, and disposal activities, no significant risks to workers or the general population is anticipated. Section VIII of the Occupational Safety & Health Administration (OSHA) Technical Manual (OSHA 1999) should be consulted for information on selecting the appropriate types of PPE.  The risk screen indicates that the use of the proposed substitute in normally unoccupied spaces will be less harmful to the atmosphere than the continued use of Halon 1301.  Additionally, the risk to the general population is expected to be below levels of concern for non-cancer risks.  
ATMOSPHERIC ASSESSMENT
This section presents an assessment of the potential risks to atmospheric integrity posed by the use of KSA as a flooding agent in normally unoccupied areas. According to the applicant, the active ingredients for this technology are solids both before and after accidental dispersion; therefore, the ozone-depleting potential (ODP), global warming potential (GWP) and the atmospheric lifetime (ALT) are all zero (Kidde SNAP Submission 2008).  Accordingly, use of KSA is not expected to pose any significant adverse atmospheric impacts.
OCCUPATIONAL EXPOSURE ASSESSMENT
The potential for personnel exposure during manufacture, installation and maintenance, and clean-up are examined in this section.  The discharge scenarios discussed are assumed to occur accidentally and not as the result of a fire.  
Occupational Exposure During Manufacture
 As described by the submitter, workers could be exposed to KSA during manufacture, sometimes for extended periods of time.  Due to the highly respirable nature of the substitute, and the long periods of exposure, manufacturing employees should wear appropriate PPE, such as protective clothing, gloves, goggles, and respiratory protection, selected in accordance with the OSHA Technical Manual (OSHA 1999).  Additionally, rooms in which personnel are working should be well ventilated with a local exhaust system and an eye wash fountain and quick drench facilities must be close to the production area. In the case of an accidental spill, workers should immediately vacate the premises and follow the first aid guidelines listed in the MSDS.  The recommendations for clean-up discussed in Section 4.3 should be followed. 
Occupational Exposure During Installation and Maintenance
The post-activation product is entirely particulate, and as indicated by the submitter, of such a size which makes it highly respirable and able to reach the extrathroracic, tracheo-bronchial, and pulmonary regions of the respiratory system (Kidde SNAP Submission 2008; EPA 1994b).  As such, proper PPE should be used.  In the following sections, recommended PPE for exposure at installation and maintenance, are detailed.  The main constituent of the substitute, despite having low toxicity, can also pose a human health risk because it can raise blood pH if inhaled in sufficient quantities.  However, blood pH modeling indicates that the levels of this constituent in KSA are not expected to pose a significant health risk (see Section 4.2.1.1).  
Installation and Maintenance
When the KSA system is activated, there is little warning time before the system disperses.  Given the fine particle size of the proposed substitute, the high levels to which personnel may be exposed (Table 3) and the short warning time, personnel performing installation or maintenance work should wear appropriate PPE (i.e., protective clothing, goggles, gloves and respiratory protection), according to the OSHA Technical Manual .  Installation personnel should also receive training so as to minimize the risk for accidentally discharging the system while performing installation.  

Table 3:  Maximum Expected Exposure Levels and
 Toxicological Thresholds for KSA Constituents and Impurities
                                  Constituent
                                 Occupational 
                               Exposure (mg/m[3])
                                   IDLH [a]
                                   (mg/m[3])
                                  NIOSH REL a
                                   (mg/m[3])
                                  OSHA PEL a
                                    (mg/m3)

             NA = Not available 
            a Source: (NIOSH 2007).
      Exposure After Release
The proposed powdered extinguishing agent contains soluble particles of a compound that, when inhaled, may deposit in the respiratory tract.  These soluble particles could potentially cross the biological membranes of the respiratory system and enter the systemic circulation.  The absorption of a large amount of this constituent could potentially have an impact on the body's acid-base balance.  To determine the potential impact on the body's acid-base balance of exposure to this constituent via inhalation, the effect of an accidental release of KSA was modeled.

Using information provided by the submitter, a reasonable worst-case release scenario was constructed in which a release of the proposed substitute occurs, exposing maintenance personnel to the maximum design concentration provided by the submitter.  The following assumptions were made regarding the constituent that could potentially impact the body's acid-base balance:

   * all constituent particles (i.e., 100%) are small enough to be respirable (EPA 1994b);
            
   * all of the inhaled constituent is soluble and enters the systemic circulation;
            
   * exposed to this level of particulate matter, the room occupant's breathing pattern will become shallow and rapid, with a respiratory rate of 40 breaths per minute at a tidal volume of 150 mL/breath (Sherwood 2005); and
            
   * the human body has 70 mL blood/kg; therefore, a 70 kg male has 4.9 L of blood and a 57 kg female has 4.0 L of blood (Guyton and Hall 1996).
      
Given the assumptions listed above, the model indicates that at the maximum blood pH resulting from accidental release of KSA in the protected space, no significant adverse health effects are expected.  The body has compensatory mechanisms including a decrease in the respiratory rate, which increases blood levels of CO2, forming carbonic acid that neutralizes the increased blood and extracellular pH. In addition, the kidneys increase blood filtration.  Post-exposure oral application of 8-12 ounces of electrolyte-containing fluids, such as orange juice or a sports drink, which contain high levels of potassium, will help restore the normal physiological electrolyte balance, and will help restore kidney function.  Additionally, as the kidneys will be working harder than usual, personnel should also increase their water intake for about a week after exposure.
Post-Activation Clean-Up
Only one application in which KSA may be used has an audible horn warning of impending discharge.  Therefore, unless there is a witness to the KSA system discharge or there is some other means of determining the exact time of discharge (e.g., security camera record), clean-up workers would not know when the system had discharged and thus would not know when all particles from the system would have settled.  Prior to cleanup, the air exchange rate in the room should be increased in order to aerate the space and reduce humidity.  Also, spraying a dust suppressant compound should minimize the re-circulation of nuisance dust particles.  

To minimize exposure to dust particles, it is recommended that all workers entering the protected volume to clean-up after activation wear appropriate PPE (i.e., protective clothing, goggles, gloves and respiratory protection) in accordance with the OSHA Technical Manual (OSHA 1999).

The contents removed from the protected volume should be disposed of according to federal, state and local regulations.  By adhering to safety guidelines mentioned above in Section 4, the potential for excessive worker exposures to KSA during post-activation cleanup will be unlikely.
GENERAL POPULATION EXPOSURE ASSESSMENT
This section screens potential risks to the general population from exposure to ambient air releases of KSA constituents.  Factory releases (occurring during manufacture) and on-site releases (those occurring at the end-use) are examined in this section. By following existing regulations, factory or on-site releases are not likely to pose a significant threat to ambient air, surface water, or solid waste.  Consequently, use of KSA is not expected to pose significant risk to the general population.   
Ambient Air
All manufacturing occurs in a facility with certain engineering controls in place, so minimal release to the ambient air is expected.  Installation and servicing occur in very large sites, so releases in such locations are expected to be well below the acceptable exposure limits.  Therefore, air emissions associated with the manufacture and use of KSA are not of concern to the health of the general population.   
Surface Water
If all the solid waste settles onto the floor of the unoccupied space and is removed from the site according to federal, state, and local requirements, the KSA components are not likely to settle into nearby streams or ponds. 
Solid Waste 
If all spilled and settled material in the manufacturing facility and all on-site releases are cleaned up and disposed of according to federal, state, and local requirements, no release to the environment is expected.  

VOLATILE ORGANIC COMPOUND ASSESSMENT
The KSA constituents are not considered VOCs for purposes of local air quality.    

REFERENCES
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. 
EPA. 1994b. Methods for Derivation of Inhalation Reference Concentrations and Application of Inhalation Dosimetry.  Office of Research and Development, U.S. Environmental Protection Agency.  EPA/600/8-90/066F. October 1994.  Available online at http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=71993. 
Guyton, A.C., MD and Hall, J.E., PhD. 1996. Textbook of Medical Physiology 9th ed. W.B. Saunders Co.,  Philadelphia. p.  299.
Kidde SNAP Submission. 2008. Significant New Alternatives Policy Program Submission to the United States Environmental Protection Agency, July 2008. 
NFPA. 2006.  NFPA 2010: Standard for Fixed Aerosol Fire-Extinguishing Systems.  National Fire Protection Agency.    
NIOSH.  2007.  NIOSH Pocket Guide to Chemical Hazards.  Department of Health and Human Services, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health.  Publication No. 2005-149.  September 2007.
OSHA.  1999.  OSHA Technical Manual. Department of Labor.  Occupational Safety and Health Administration. January 20, 1999.  Available online at <http://www.osha.gov/dts/osta/otm/otm_toc.html>.
Sherwood, L.  2005.  Fundamentals of Physiology: A Human Perspective.  Brooks  Cole, 2005.  Viewable online at: < http://books.google.com/books?id=4INVi-m7gX8C&>.