Engines used for different types of service require fuels with specific chemical and physical properties, and individual specifications have evolved to meet those needs. Commercial and military fuels1 are made by blending kerosene fractions with low-boiling-point fractions containing more-volatile hydrocarbons. Except for the additives, the chemical composition of most military fuels is similar to kerosene. Commercial illuminating kerosene was chosen to fuel early military jet engines, largely because it was readily available and its use would not interfere with the need for gasoline, which was in short supply during wartime. After World War II, commercial jet-aircraft engines were designed to use primarily kerosene-like fuels. High-altitude flying requires fuel with a low freezing point; also, the fuel must be free
The term "military fuels" in this report refers only to JP-5, JP-8, and DFM vapors.
of foreign matter, have little moisture, burn cleanly (essentially free of smoke), and not cause corrosion of engine parts in prolonged service.
Jet-propulsion (JP) fuels JP-4 and JP-8 are the major fuels used for land-based military aircraft. The requirements for naval aircraft are somewhat different from those for land-based aircraft. Less-volatile, high-flash-point fuels are needed to minimize exposure of personnel to vapors and to reduce fire risk, particularly in enclosed areas below decks. To meet those needs, JP-5, a 60°C high-flash-point kerosene-like fuel, was developed for shipboard service. The Navy also uses JP-5 and JP-8 fuels for tanks, trucks, and jeeps to reduce the requirement for different fuels.
Because of its concern for the health of personnel exposed to vapors from fuels in strategic sealift ships, the U.S. Navy's Occupational Safety and Health Standards Board proposed interim exposure limits of 350 mg/m3 and 1,800 mg/m 3 as the 8-hr permissible exposure limit (PEL) and the 15-min short-term exposure limit (STEL), respectively (U.S. Navy Environmental Health Center, 1993).
The strategic sealift ships will be used to transport fueled vehicles, thus eliminating fueling at docking and permitting deployment onto the field as soon as the vehicles are unloaded from the ship. Fueled armored tanks, tanker trucks, other trucks of various sizes, trailors, jeeps, and helicopters will be stored in the ship's cargo holds, transported, and taken off the ship. The proposed interim exposure limits for the military fuels correspond with the U.S. National Institute of Occupational Safety and Health's recommended regulatory levels for more-volatile petroleum distillates (NIOSH, 1976). No other federal standards exist for these fuels.
The Navy also requested that the National Research Council (NRC) review the toxicological data on JP-5, JP-8, and diesel fuel marine (DFM); determine if the Navy's proposed interim PELs and STELs for the three fuels are appropriate; and, if necessary, propose revisions of the PELs and STELs.
The NRC assigned the project to the Committee on Toxicology (COT), which convened the Subcommittee on Permissible Exposure Levels for Military Fuels. The subcommittee reviewed the toxicity data and assessed the adequacy of the Navy's interim PELs and STELs for the three fuels. The report of the subcommittee is intended to aid the Navy in finalizing exposure limits for JP-5, JP-8, and DFM to protect naval personnel from toxic exposures to vapors from these fuels.
The subcommittee reviewed information regarding (1) the physical and chemical properties of JP-5, JP-8, and DFM, as well as JP-4 because of its similarities to the other fuels and because of its larger data base, (2) operational scenarios that might result in exposure to the fuel vapors, (3) toxicokinetics (of uptake and distribution) of the fuel vapors, and (4) epidemiological as well as toxicological evidence of adverse health effects resulting from exposure to the fuels.
These reviews are summarized in this report. Chapter 2 contains descriptions of the physical and chemical properties of the three fuels. Chapter 3 describes the toxicokinetic effects of exposure to the fuel vapors; Chapter 4 discusses the testing and monitoring of the fuels; Chapter 5Chapter 6Chapter 7Chapter 8 through Chapter 9 report on the effects of fuel-vapor exposure on the kidney, blood, central nervous system, liver, and cardiovascular system, respectively. Chapter 10 and Chapter 11 provide data on the carcinogenic and genotoxic effects of exposure, and Chapter 12 summarizes dermal and ocular toxicity studies conducted on several fuels. Chapter 13 contains the subcommittee's conclusions and recommendations on the Navy's proposed exposure limits for the fuels. No studies on the reproductive toxicity and immunotoxicity of these fuel vapors were found in the literature.
The major health effects resulting from inhalation of fuel vapors are noncarcinogenic effects on the central nervous system, kidney, and liver. The subcommittee's recommendations for PELs and STELs are based on the reported noncarcinogenic effects and apply only to the inhalation of vapors and not to the aerosolized
fuel. If the Navy finds evidence that there is exposure or a potential for exposure to respirable aerosols of the fuels, modified guidelines for limiting such exposures will have to be developed because of concern that the toxicity is greater from the less-volatile fractions in aerosols than from the more-volatile fractions in vapors. In addition, the subcommittee notes that the International Agency for Research on Cancer (IARC) concluded that DFM is possibly carcinogenic to humans in view of the results of rodent skin-painting studies (IARC, 1989).