Jet-propulsion fuel 8 (JP-8) is a kerosene-based multipurpose fuel that is in wide use by the U.S. military. The military is in the process of converting to JP-8 for use in all its aircraft (except Navy ship-based aircraft, which will continue to use JP-5), ground vehicles, and support equipment, such as generators, cooking stoves, and tent heaters (Makris 1994; Edwards et al. 2001).
There are several reasons for the conversion: using a single fuel will eliminate many logistical problems associated with transporting and distributing multiple fuels to various bases within the United States and to U.S. operations in other countries (Makris 1994); JP-8 is produced from jet fuel A and jet fuel A-1, which are used in commercial aircraft and are readily available throughout the world (Makris 1994; USAF 1996; Chevron 2000); it has a higher flash point than several other jet fuels used by the military (such as wide-cut jet fuels, which are mixtures of gasoline and kerosene) and is therefore less flammable and less likely to ignite accidentally (Zeiger and Smith 1998); and it has a lower vapor pressure than wide-cut jet fuels, so less fuel is lost to evaporation (Makris 1994). The U.S. Department of Defense (DOD) identified JP-8 as its single military fuel in the 1980s, but the conversion has been gradual because of the need to modify engines and other equipment (Zeiger and Smith 1998). The conversion to JP-8 is scheduled to take approximately 20 years.
The U.S. military services and the North Atlantic Treaty Organization forces use an estimated 5 billion gallons of JP-8 each year (Zeiger and Smith
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1 Introduction Jet-propulsion fuel 8 (JP-8) is a kerosene-based multipurpose fuel that is in wide use by the U.S. military. The military is in the process of converting to JP-8 for use in all its aircraft (except Navy ship-based aircraft, which will continue to use JP-5), ground vehicles, and support equipment, such as generators, cooking stoves, and tent heaters (Makris 1994; Edwards et al. 2001). There are several reasons for the conversion: using a single fuel will eliminate many logistical problems associated with transporting and distributing multiple fuels to various bases within the United States and to U.S. operations in other countries (Makris 1994); JP-8 is produced from jet fuel A and jet fuel A-1, which are used in commercial aircraft and are readily available throughout the world (Makris 1994; USAF 1996; Chevron 2000); it has a higher flash point than several other jet fuels used by the military (such as wide-cut jet fuels, which are mixtures of gasoline and kerosene) and is therefore less flammable and less likely to ignite accidentally (Zeiger and Smith 1998); and it has a lower vapor pressure than wide-cut jet fuels, so less fuel is lost to evaporation (Makris 1994). The U.S. Department of Defense (DOD) identified JP-8 as its single military fuel in the 1980s, but the conversion has been gradual because of the need to modify engines and other equipment (Zeiger and Smith 1998). The conversion to JP-8 is scheduled to take approximately 20 years. The U.S. military services and the North Atlantic Treaty Organization forces use an estimated 5 billion gallons of JP-8 each year (Zeiger and Smith
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1998; Henz 1998). Military personnel are exposed to JP-8 during aircraft fueling and maintenance operations. Because of JP-8’s comparatively low volatility and higher flash point than some other jet fuels (e.g., JP-5), jet engines powered by it do not start as easily or burn fuel as completely, particularly under cold conditions, as they do when powered by wide-cut jet fuels. Cold-engine starts are known to produce plumes of unburned aerosolized fuel. Workers involved with fueling operations on aircraft are exposed to JP-8 vapor, aerosol, and liquid during startup procedures. There are also anecdotal reports from exposed workers of dizziness, skin irritation, and of smelling and tasting the fuel hours after exposure (Zeiger and Smith 1998). For additional general information on JP-8, consult the Agency for Toxic Substances and Disease Registry’s Toxicological Profile for Jet Fuels (JP-5 and JP-8) (ATSDR 1998). DOD recommended an interim permissible exposure level (PEL) for JP-8 of 350 mg/m3 (NRC 1996). A PEL is an allowable time-weighted exposure concentration in workplace air averaged over an 8-hr shift. No other national agencies or organizations have recommended regulations or guidelines applicable to JP-8. Two agencies have established regulations for petroleum distillates: the National Institute for Occupational Safety and Health (NIOSH) set an 8-hr recommended exposure limit (REL) time-weighted average (TWA) of 350 mg/m3, and the Occupational Safety and Health Administration (OSHA) set a PEL TWA of 2,000 mg/m3 (NIOSH 1997; OSHA 29 CFR 1910.1000 ). NIOSH has established a REL TWA of 100 mg/m3 for kerosene (NIOSH 1997). The American Conference of Governmental Industrial Hygienists (ACGIH) recently proposed a Threshold Limit Value for kerosene and jet fuels (as a total hydrocarbon vapor) of 200 mg/m3 (ACGIH 2002). ExxonMobil Biomedical Sciences, Inc., has set occupational exposure levels for kerosene and other middle distillate fuels of 500 mg/m3 for vapors and 5 mg/m3 for aerosols (ExxonMobil Biomedical Sciences, Inc. 2001). The International Agency for Research on Cancer concluded that jet fuel is “not classifiable” as to its carcinogenicity in humans (IARC 1989). ACGIH classified kerosene and jet fuels as “confirmed animal carcinogens with unknown relevance to human skin” (ACGIH 2002). SUMMARY OF 1996 NATIONAL RESEARCH COUNCIL REPORT ON MILITARY FUELS In 1996, the National Research Council (NRC) released the report of the Committee on Toxicology (COT) Subcommittee on Permissible Exposure Levels for Military Fuels, which evaluated DOD’s interim PEL of 350 mg/m3 by reviewing data on the toxicity of the vapors from JP-4, JP-5, JP-8, and
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diesel fuel marine in experimental animals and humans (NRC 1996). The executive summary from that report is presented as Appendix A. The Subcommittee on Permissible Exposure Levels for Military Fuels judged that, on the basis of available data, DOD’s PEL of 350 mg/m3 for the fuel vapors is adequate to protect the health of naval personnel exposed to them occupationally (NRC 1996). However, because of uncertainties in the database, the PEL should still be considered interim until further research has been completed. The subcommittee recommended that data be obtained on exposures during operational procedures, including exposure to respirable aerosols of unburned fuels; that studies be conducted on the possible effects of high-level acute and low-level chronic exposure to fuel vapors on the central nervous system; and that research be conducted on the effect of fuel vapors on hepatotoxicity in experimental animals to help to identify a no-observed-adverse-effect level for JP-8 with greater confidence. THE CHARGE TO THE SUBCOMMITTEE Since the release of the 1996 NRC report, additional data on JP-8 have been generated. In light of those data, the U.S. Air Force asked the NRC to review the toxicologic, epidemiologic, and other relevant data on JP-8 vapors and aerosols to assess the scientific basis of the interim PEL of 350 mg/m3 proposed by DOD, identify data gaps, and make recommendations for future research relevant to deriving the PEL. The NRC assigned the project to COT and assembled the Subcommittee on Jet-Propulsion Fuel 8, which prepared the present report. THE SUBCOMMITTEE’S APPROACH TO ITS CHARGE The subcommittee reviewed information regarding the physical and chemical properties of JP-8, military operational scenarios that might result in exposures to fuel vapors and aerosols, toxicokinetics of the fuel, and epidemiologic and toxicologic evidence of adverse health effects of exposures to JP-8 vapors and aerosols. Because JP-8 is a kerosene-based fuel and its toxicologic properties are thought to be similar to those of kerosene, the subcommittee also reviewed toxicity data on kerosene and other kerosene-based fuels. The subcommittee used the body of information on JP-8, kerosene, and other kerosene-based fuels to evaluate the interim PEL of 350 mg/m3 and determine whether it is adequate to protect the health of military personnel exposed to JP-8 occupationally.
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PHYSICAL AND CHEMICAL PROPERTIES OF JP-8 JP-8 is a complex mixture containing more than 200 aliphatic and aromatic hydrocarbon compounds with nine to 17 (or perhaps more) carbon atoms, including thousands of isomeric forms that distill at 170-325°C, and three to six nonhydrocarbon performance additives (Henz 1998; DOD 1992). The precise composition of JP-8 varies from batch to batch. Some of the physical and chemical properties of JP-8 are summarized in Table 1-1, and the additives in JP-8 are summarized in Table 1-2. The hydrocarbon portion of jet fuels is made from low-sulfur or desulfurized distillate kerosene streams, usually blended with cracked or hydrocracked heavier streams to produce a fuel that meets specific performance specifications. JP-8 is an extremely complex mixture with specifications established for boiling point, sulfur (maximal percentage, 0.3%), olefins (maximal percentage, 5.0%), and aromatics (maximal percentage, 22%) (Vere 1984). The aromatics limit is primarily to prevent excessive smoke production during combustion. Aside from the aromatics, most of the remainder of JP-8 consists of the n-alkanes, isoalkanes, and naphthenics component classes. There is no minimal requirement for the aromatics class, and aromatics are generally not desired in jet fuels. In addition to hydrocarbons, jet fuel contains small amounts of sulfur and nitrogen as heterocyclic substituents generally in structures containing one or two rings. At a boiling point of about 500ºF, an atmospheric petroleum distillate stream (kerosene) has about 4,000 different n-alkanes and isoalkanes. Combinations of the naphthenes, aromatics, and heterocyclics are also present, and the total number of components is very large. The approximate ranges of the major hydrocarbon classes (by volume %) in JP-8 are as follow (Vere 1984): n-alkanes + isoalkanes 33-61% olefins 0.5-5% naphthenes (naphthenics) 10-45% aromatics 12-22% ORGANIZATION OF THIS REPORT This report contains 11 chapters in addition to this introductory chapter. Chapter 2 describes issues relevant to assessing exposure of military personnel to JP-8. Chapter 3 discusses the toxicokinetics and toxicody-namics of JP-8. Chapters 4-10 summarize studies on the effects of JP-8 on the respiratory
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TABLE 1-1 Physical and Chemical Properties of JP-8 Molecular weight: » 180 Synonyms: Jet fuel JP-8, kerosene, aviation kerosene, fuel oil no. 1, jet kerosene, turbo fuel A, straight-run kerosene, distillate fuel oil–light, MIL-T-83133B, AVTUR, NATO F-34 CAS registry number: 8008-20-6 (kerosene)/70892-10-3 (fuel oil 1) Freezing point, maximum: -47ºC Boiling point: 175-300ºC 10% recovered, maximum: 205ºC End point, maximum: 300ºC Flash point, minimum: 38ºC Vapor pressure: 0.52 mm Hg (10ºC), 1.8 mm Hg (28ºC) Specific gravity, kg/L, 15ºC, minimum: 0.775 maximum: 0.840 Heating value, Btu/lb, minimum: 18,400 Viscosity, maximum at -20ºC: 8 Physical state: Liquid Color: Clear and bright Solubility in water: 5 mg/L (kerosene) Vapor density (air = 1): 4.5-5 Liquid density (water = 1): 0.788-0.845 kg/L Odor: Kerosene-like Conversion factors at standard temperature and pressure: 1 ppm = 8.0 mg/m3 1 mg/m3 = 0.125 ppm Sources: NRC 1996; ATSDR 1998. tract, the nervous system, the immune system, the liver, the kidney, reproduction and development, and the cardiovascular system. Chapters 11 and 12 provide information on the genotoxic and carcinogenic effects of exposure to JP-8, respectively. This report also contains three appendixes. Appendix A
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TABLE 1-2 Additives in Jet-Propulsion Fuel 8 Additivea Function Quantity Required or Optional Diethylene glycol monomethyl ether (DiEGME) Ice inhibition 0.1 vol/vol % Required Stadis 450 Static inhibition 2 mg/L Required DCI-4A Corrosion inhibition 15 mg/L Required Antioxidant Inhibition of gum formation 25 ppm Optional Metal deactivator Control of metal-catalyzed fuel deterioration 3 ppm Optional aStadis 450 and DCI-4A are proprietary formulations; the antioxidant is N,N-diisopropylparaphenylene diamine or various blends of hindered phenols; the metal deactivator is N,N-disalicylidene-1,2-propanediamine or N,N-disalicylidene-1,2-cyclohexanediamine. Source: Major Tom Miller, U.S. Air Force, Wright-Patterson Air Force Base, Ohio. contains the executive summary from the 1996 Research Council report Permissible Exposure Levels for Selected Military Fuel Vapors;Appendix B contains the executive summary and introduction of JP-8 Final Risk Assessment, an unpublished report summarizing a recent Air Force-funded human-health study on JP-8; and Appendix C reviews types of tests used to assess neurologic function in humans after exposure to JP-8. REFERENCES ACGIH (American Conference of Governmental Industrial Hygienists). 2002. Threshold Limit Values and Biological Exposure Indices. American Conference of Governmental Industrial Hygienists, Cincinnati, OH. ATSDR (Agency for Toxic Substances and Disease Registry). 1998. Toxicological Profile for Jet Fuels (JP-5 and JP-8). U.S. Department of Health and Human Services, Public Health Service, Agency for Toxic Substances and Disease Registry, Atlanta, GA. Chevron. 2000. Technical Review of Aviation Fuels. San Ramon, CA: Chevron Products Company. DOD (U.S. Department of Defense). 1992. Military Specifications: Turbine Fuel, Aviation, Grades JP-4, JP-5, and JP-5/JP-8 ST. MIL-T5624P.
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Edwards, R., B. Harrison, and L. Maurice. 2001. Properties and Usage of Air Force Fuel: JP-8. AIAA 2001-0498. Presentation at the 39th Aerospace Meeting and Exhibit, Reno, NV, Jan. 8-11, 2001. American Institute of Aeronautics and Astronautics, Inc., Reston, VA. ExxonMobil Biomedical Sciences, Inc. 2001. ExxonMobil Occupational Exposure Limits for Chemical Contaminants. ExxonMobil Biomedical Sciences, Inc., Annandale, New Jersey. Henz, K. 1998. Survey of Jet Fuels Procured by the Defense Energy Support Center, 1990-1996. Defense Logistics Agencies, Ft. Belvior,VA. IARC (International Agency for Research on Cancer). 1989. Occupational Exposures in Petroleum Refining, Crude Oil and Major Petroleum Fuels. IARC Monographs on the Evaluation of Carcinogenic Risks to Humans, Vol. 45. Lyon: International Agency for Research on Cancer, World Health Organization. Makris, N.J. 1994. JP-8: A conversion update. Flying Safety 50(10):12-13. NIOSH (National Institute for Occupational Safety and Health). 1997. NIOSH Pocket Guide to Chemical Hazards. DHHS (NIOSH) 97-140. U.S. Dept. of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, Cincinnati, OH. NRC (National Research Council). 1996. Permissible Exposure Levels for Selected Military Fuel Vapors. Washington, DC: National Academy Press. USAF (U.S. Air Force). 1996. History of Aviation Fuel Development in the U.S. Air Force Research Laboratory, Propulsion Directorate, Fuels Branch, U. S. Air Force. Vere, R.A. 1984. Aviation fuels. Pp. 723-771 in Modern Petroleum Technology, Part 2, 5th Ed., G.D. Hobson, ed. Chichester: John Wiley & Sons. Zeiger, E., and L. Smith. 1998. The first international conference on the environmental health and safety of jet fuel. Environ. Health Perspect. 106(11):763-764.