Idézet: GI - Dátum: 2004. aug. 14., szombat - 0:30
Hydrocarbons associated with JP-4 and JP-7 have been detected in air in closed buildings where thefuels were being used or burned. Organic compounds found in JP-4 have been detected ingroundwater following JP-4 leaks and spills. Hydrocarbons associated with JP-4 have also been foundin soil surrounding fuel spill and leak sites. No data were located on the contamination of food, fish,shellfish, or terrestrial plants or animals.
JET FUELS JP-4 AND JP-7 805. POTENTIAL FOR HUMAN EXPOSURE The National Occupational Exposure Survey conducted by NIOSH between 1980 and 1983 estimated that 4,866 employees had the potential to be exposed to JP-4 in the workplace (NOES 1990).Populations most likely to be exposed to JP-4 and JP-7 include those involved in jet fuelmanufacturing or refueling operations, populations working or living on Air Force bases where thefuels are used and stored (and where leaks or spills are likely to occur), and those living or workingnear waste sites where the fuels are dumped.JP-4 has been found in at least 4 of the 1,397 NPL hazardous waste sites that have been proposed forinclusion on the EPA National Priorities List (NPL) (HazDat 1994). JP-7 has not been found in anyNPL site. However, the number of NPL sites evaluated for JP-4 and JP-7 is not known. Thefrequency of these sites within the United States can be seen in Figure 5-1.5.2 RELEASES TO THE ENVIRONMENTJP-4 and JP-7 are fuel mixtures used by the U.S. military as aviation fuels. As a result of normalaircraft operations and fuel storage, JP-4 and JP-7 can be released into the environment. Under someconditions, it is common practice for aircraft to jettison excess fuel, releasing it into the environment(IARC 1989).Since JP-4 and JP-7 releases are not required to be reported under SARA Section 313, there are nodata for JP-4 and JP-7 in the Toxics Release Inventory (TRI 1993).5.2.1 AirJP-4 may be released into the atmosphere as vapors in loading and unloading operations in closedaircraft shelters (Air Force 1981h; NIOSH 1989). Releases into the air may also occur as a result ofevaporation of JP-4 from contaminated soils or other spill sites (Air Force 1984b).5.2.2 WaterJP-4 and JP-7 may be released into groundwaters as a result of seepage from contaminated soils duringstorage, aircraft maintenance, and fuel storage and dispensing operations (Twenter et al. 1985). A fuellayer of approximately 2 feet was identified in groundwater from shallow wells at Robins Air Force Base (Georgia) on a site where an undetermined amount of JP-4 was released into the soil from anunderground fuel supply line in the 1960s (Air Force 1985a).Groundwater intrusions of JP-4 were reported to have occurred as a result of cracks in the gunnitelining of the diked area surrounding three aboveground storage. tanks at the Niagara Falls Air ForceReserve Facility in New York (Air Force 1983a). Additional JP-4 was found in storm water drainingsat the facility from underground inlet pipe, and in&t and outlet pipe leaks discovered in 1979 and1982, respectively. Hydrocarbon groundwater contamination from leaking pipes in a JP-4 fuel farmoccurred in a residential area surrounding the U.S. Navy air station in Traverse City, Michigan(Sammons and Armstrong 1986).5.2.3 SoilJP-4 and JP-7 may be released into soil as a result of leaks in underground or aboveground storagetank systems. In October 1975, approximately 83,000 gallons of JP-4 were lost from the bottom of anewly cleaned, aboveground storage tank at the Defense Fuel Supply Center in Charleston, SouthCarolina (Talts et al. 1977). Investigation of the soil revealed that JP-4 had moved through poroussoil to a depth of approximately 7-14 feet. In 1972, approximately 42,000 gallons of JP-4 werereleased into the soil as a result of an external pipe leak at O’Hare Air Reserve Forces Facility, Illinois(Air Force 1983b). The dike had accumulated excess water as a result of heavy rains, and a drop intemperature caused the water to freeze and crush external piping to the tank. An undeterminedamount of JP-4 was released into the soil from a leak in a 4-inch diameter pipe in 1965 at Robins AirForce Base (Air Force 1985a). Approximately 27,000 gallons of JP-4 were released into the soil inJanuary 1985 as a result of an automatic filling system malfunction which caused underground storagetanks to overfill at Hill Air Force Base in Utah (Elliot and DePaoli 1990).5.3 ENVIRONMENTAL FATE5.3.1. Transport and PartitioningSince JP-4 and JP-7 are mixtures of hydrocarbons, their movement in the environment is actually afunction of the chemical and physical properties of the component hydrocarbons. Following release ofjet fuel to air, water, or soil, the component hydrocarbons partition relatively independently of each other based on their respective vapor pressures, solubilities, and Henry’s law and sorption constants.For JP-4 and JP-7 mixtures, these values are ranges based on the component hydrocarbons.Information on the specific physical and chemical properties of several of the componenthydrocarbons (e.g., benzene, toluene, xylene, naphthalene, etc.) can be found in the ATSDRtoxicological profiles for these chemicals. The hundreds of hydrocarbons making up JP-4 and JP-7fuel mixtures can be divided into a few groups of hydrocarbon classes with similar properties (AirForce 1989b; CRC 1984). These include paraffins (saturated straight-chain hydrocarbons),cycloparaffins (saturated cyclic hydrocarbons), aromatics (fully unsaturated six-carbon ringcompounds), and olefins (unsaturated straight-chain and cyclic hydrocarbons). Paraffins andcycloparaffins are the major components and comprise about 90% of JP-4 by volume (79% by weight)(Air Force 1989b). Aromatics make up about 10-25% by volume of JP-4 but only about 5% of JP-7(Air Force 1989b; IARC 1989); however, the specific composition of these fuels varies amongmanufacturers and probably between batches (Cooper et al. 1982). Jet fuel may also contain low andvariable levels of nonhydrocarbon contaminants and additives such as sulfur compounds, gums,alcohols, naphthenic acids, antioxidants, metal deactivators, and icing and corrosion inhibitors (CRC1984; IARC 1989). The variability in the composition contributes to the difficulty in making generalconclusions about the fate and transport processes of these fuels in the environment.Most of the principal JP-4 component hydrocarbons rapidly evaporate from water following a spill.Tests with both petroleum- and shale-derived JP-4 under various environmental conditions all showedvolatilization of JP-4 component hydrocarbons to be the dominant fate process (Air Force 1987b,1988b; EPA 1985). Complete evaporation of benzene, toluene, and p-xylene occurred within 24 hoursin shake-flask experiments using water from three natural sources (EPA 1985). Ninety percent of theJP-4 evaporated within 6 days under the laboratory conditions used (Air Force 1988b). As expected,the hydrocarbons with the lowest boiling points evaporated most rapidly. Simulated spills of JP-4 towater suggested that most JP-4 component hydrocarbons evaporated within l-2 weeks followingrelease (Air Force 1981f). In a model petroleum-derived JP-4 fuel spill into a natural freshwatersample, initial concentrations of total dissolved hydrocarbons were about 1 mg/L. At 1 and 2 weeksfollowing the simulated spill, concentrations did not exceed 0.005 mg/L for any of the measured fuelcomponents. This was attributed to the high volatility of the fuel. Shake-flask experiments haveshown that increased dissolved organic carbon decreases the rate of hydrocarbon evaporation (AirForce 1988b). Laboratory experiments have shown that the evaporation rate of jet fuel and itscomponents increases with wind velocity and, to a lesser extent, with temperature and fuel-layer thickness (Air Force 1988d). Comparisons of dissolution and evaporation rates under severalwindspeed and mixing conditions showed that evaporation was the dominant fate process for jet fuelcomponents in water.JP-4 also evaporates from soil, although evaporation is not as important a fate process in soil as it is inwater. A model soil core ecosystem was treated with JP-4 to simulate a spill (Air Force 1981e,1982c). Headspace above the soil core revealed hydrocarbons from the JP-4 indicating thatevaporation of component hydrocarbons had occurred. In model soil core ecosystems, volatilizationaccounted for 7% of the hydrocarbon loss compared to 93% for biodegradation (Coho 1990).Some downward migration of JP-4 component hydrocarbons occurred in model soil core ecosystemstreated with JP-4 to mimic a spill and watered to simulate rainfall (Air Force 1982c). Of ninehydrocarbons monitored for vertical migration through the core, only n-pentadecane and n-heptanemigrated the 50 cm to the bottom of the core. They were first found at this depth 197 days followinginitiation of the experiment. These two compounds also persisted in the soil longer than the otherhydrocarbons monitored. n-Decane, n-undecane, dodecane, n-tridecane, and n-tetradecane were foundonly at 10 cm below the surface. They were observed for 50-134 days following onset of theexperiment and were not detected again. Additional data obtained by leachate collection indicated thatthe migration of hydrocarbons was best explained by channeling effects caused by biota and/orphysical stresses since there was no direct correlation between leachate collection and hydrocarbontransport. Additional evidence for vertical migration of jet fuel hydrocarbons through soil comes fromtheir detection in groundwater following leaks and spills to surface soil (EPA 1990b; Talts et al.1977). Horizontal and vertical migration through soil has been confirmed by detection of JP-4hydrocarbons in soil several meters from the spill site (EPA 1988a, 1990b).The difficulties of determining the fate of JP-4 and its components are epitomized by the problems indetermining the composition of its water-soluble fraction. Various results are likely to be obtained bydifferent investigators even when the fuel tested and the methods used appear to be similar. Seventeenhydrocarbons were detected in an analysis of the water-soluble fractions of shale-derived andpetroleum-derived JP-4, with the most abundant hydrocarbons being benzene, methylbenzene, and3-methylhexane (Air Force 1988b). In contrast, only benzene, toluene, and p-xylene were found insignificant concentrations in the water-soluble fraction of JP-4 (origin not specified) in laboratorysimulations of field conditions, although other hydrocarbons could be detected (EPA 1985). The aqueous concentration of JP-4 components under spill conditions was found to depend on thesolubility of the individual components, the mixing of the mixture due to wind speed, the thickness ofthe fuel layer, the ionic strength of the aqueous solution, and the rate of evaporation of components(Air Force 198%). Laboratory experiments simulating a JP-4 spill to water measured both evaporationand dissolution of components under slow and fast wind speeds and under conditions that enhancedcomplete mixing. Under both conditions, only the component aromatics (benzene, toluene,ethylbenzene, and xylene) were soluble enough to-be detected in the aqueous phase before evaporativeprocesses reduced their concentrations below detectable limits. Concentration measurements of thesecomponents in both the fuel and water suggested that, in general, the concentration of the lighteraromatics decreased in the fuel layer and increased in the water phase until evaporation began tosubstantially affect their concentration in the aqueous phase. Heavier aromatics initially decreased inthe fuel but then increased as the lighter aromatics decreased. Aqueous concentrations increased overtime and generally reached higher levels, and their evaporation was not as rapid. Increased windspeed increased both dissolution and evaporation of JP-4 components, but evaporation was increasedsubstantially more than dissolution (a 5fold increase for evaporation compared to a 2-3-fold increasefor dissolution). At both wind speeds, evaporation was dominant with rates on the order of mg/minutecompared to dissolution rates in the pg/minute range. When sea water was used as the test medium,results were similar; however, the concentrations of the hydrocarbons dissolved in sea water wereconsiderably less than when distilled water was used. This was attributed to the effect of high ionicstrength on the solubility of the hydrocarbons. Increased thickness of the fuel layer increased theconcentration of the dissolved hydrocarbons because evaporation was reduced. This increased thecontact time between fuel components and the water. Solubility has also been found to increase withincreasing concentrations of dissolved organic carbon (Air Force 1988b).Movement of JP-4 on and in water was found to affect the important processes of evaporation anddissolution of JP-4 components. Variations in wind speed, the force responsible for mixing of fuel,created eddies in the aqueous medium that caused non-uniform variations in concentration of fuelcomponents with water depth and increased evaporation. Experiments that examined spreading rate ofa fuel film on water indicated that spreading was very rapid (Air Force 1988d). Tests showed thatspreading was initially uniform, but as evaporative effects became noticeable, spreading became lessuniform and the film eventually disintegrated. Rapid spreading reduced dissolution of the fuel byincreasing evaporation and decreasing contact time. The data on the role of sediments in the fate of JP-4 and its components are contradictory. However,partitioning of jet fuel hydrocarbons to sediment does not seem to be an important fate process (AirForce 1981f; EPA 1985). Some data suggest that, under certain conditions, JP-4 hydrocarbons mayadsorb to sediment and reduce volatilization (Air Force 1988b; EPA 1985). Quiescent bottle testsusing natural water from a salt water marsh, a brackish polluted bay, and a freshwater river showedthat volatility was reduced in sterile controls containing water and sediment compared to sterilecontrols containing only water (Air Force 1988b). “In contrast, when undisturbed or shaken gently,flasks containing water and sediment, or water only, and sterile control flasks containing water fromthe same sources exhibited no difference in the rate of disappearance of components (EPA 1985).When the flasks were shaken vigorously to imitate turbulent water conditions, volatilization of somecomponents was reduced in the flasks with sediment and water compared to the flasks containingwater only. Field and laboratory data on sediment that was dosed with JP-4 and then either returnedto the pond or introduced to model laboratory systems indicate that sediment interaction of JP-4components occurs and affects the volatility of JP-4. Sediment interactions increased persistence ofJP-4 components to as much as 20 days in the field tests. Differences between laboratory and fielddata indicated that laboratory data were not good predictors of what would occur in the field.Evidence acquired using simulated petroleum- and shale-derived jet fuels indicates that neither themajor representative components nor the JP-4 mixture have strong adsorption to standard clays or tosediments from natural fresh, brackish, or salt water sources (Air Force 1981f). The data alsoindicated that the magnitude of the adsorption constant on a particular sediment was dependent on thesize and complexity of the dissolved hydrocarbon, the nature of the sediment, and the salinity of thewater and inversely correlated with the water solubility of the dissolved hydrocarbon. Temperatureand pH did not appear to have an effect on adsorption.There are no bioconcentration data on JP-4 or JP-7; however, JP-8 was found to accumulate in flagfishexposed to concentrations ranging from 1.0 to 6.8 mg/L in the surrounding water from the egg stage to128 days after hatching (Klein and Jenkins 1983). Similar results would be expected for JP-4 becauseof the similarity in composition and chemical and physical properties of these two fuels. The meanconcentration of JP-8 in the whole-body tissue samples increased with increasing concentration of thewater-soluble fraction (WSF) of the fuel. The bioconcentration factor (BCF), expressed as the ratio ofthe concentration in fish tissue to the concentration of the WSF of JP-8 in the aqueous environment,was found to be 159 (log value = 2.2). An additional experiment in adult flagfish exposed to2.54 mg/L for a 14-day period yielded a BCF of 130 (log value = 2.1). The concentrations in liver, muscle, and whole-body tissue following the 14-day exposure were 448, 165, and 329 mglkg wetweight of tissue. Placement of the fish in uncontaminated water showed a depuration rate similar tothe accumulation rate. In 14 days, whole-body tissue levels of JP-8 were reduced by about 10%.Similar experiments in rainbow trout did not show a relationship between concentrations of JP-8 in thesurrounding water and the whole-body concentration in the fish. The calculated BCF for trout wasonly 63-112 (log value of 1.8-2.1) indicating that the WSF of JP-8 does not concentrate as readily inthis species.5.3.2 Transformation and Degradation5.3.2.1 AirJP-4 has been found to react photochemically in air in the presence of nitrogen oxide compounds toform ozone (Air Force 1981b, 1982e; Carter et al. 1984). The formation of ozone decreased withincreasing altitude, decreasing temperature, and decreasing ultraviolet light intensity. Initialexperiments suggested that the nitrous oxide oxidation rates decreased with increasing pressure anddecreasing temperature. However, further tests indicated that the temperature effect may have been anartifact of the radical source used in the simulation and that the nitrous oxide oxidation rate caused byJP-4 may actually increase with altitude. Therefore, the effect of temperature on the nitrous oxideoxidation rate is uncertain. Reactions of JP-4 in the air resulted in the formation of large amounts ofaerosol material (Air Force 1981b).5.3.2.2 WaterData on the biodegradation of JP-4 components are mixed. Evidence from experiments using the WSFof JP-4 and water from three different natural sources (a pristine salt water marsh, a polluted brackishbay, and a pristine freshwater river) did not show any biodegradation (Air Force 1983f; EPA 1985).The authors of these studies attributed this to the rapid evaporation of the components from the water.In quiescent tests on the WSF of JP-4, biodegradation was observed in several flasks, but differentresults were obtained with water and/or sediment from different sources. In most tests, ethylbenzene,trimethylbenzene, and 1,4-dimethylethylbenzene were degraded. Benzene, cyclohexane, and tolueneseemed to be more resistant to biodegradation. When the sample flasks were vigorously shaken toenhance hydrocarbon-sediment interactions, evidence of biodegradation of some of the component hydrocarbons was observed. In general, the more substituted benzenes (e.g., p-xylene, ethylbenzene,methylethylbenzene, trimethylbenzene) and less volatile hydrocarbons seemed to be biodegraded.Some components were also biodegraded in similarly shaken, water-only flasks. There were somedifferences in biodegradation among the three water samples used, and biodegradation could not bedetected in the polluted bay water. The variable results obtained with the three water sources, varyingconditions, and inclusion or exclusion of sediment make it difficult to assess the relative importance ofbiodegradation of jet fuel in water. It is apparent, ‘however, that biodegradation of at least some of theJP-4 hydrocarbons does occur. Sediment appeared to decrease biodegradation. Similar experimentsusing water from the same three sources supported evidence that biodegradation of JP-4 componenthydrocarbons did occur (Air Force 1988b). Disappearance of hydrocarbons from the experimentalflasks was compared to sterile flasks containing the same type of water or water/sediment.Measurement of biodegradation rates was difficult to determine because evaporation rates were sorapid. However, some differences between experimental and control flasks were observed andinclusion of selected radiolabeled hydrocarbons supported the assertion that biodegradation did occurand could play a role in removal of JP-4 hydrocarbons from aquatic systems, particularly underconditions that reduce volatility.A comparison of field and laboratory data obtained from experiments on natural sediment dosed withJP-4 suggested that biodegradation did not occur in the field (Air Force 1987b). This was in contrastto laboratory data with the same sediment in which biodegradation was observed. The study authorsdetermined that the conflicting results indicated that laboratory tests (quiescent bottles and plexiglasstrays) were not good predictors of field behavior of JP-4 and its components. Studies of shallow wateraquifers contaminated with JP-4 indicate that the mixture does not inhibit microbial activity and thatselective aerobic biodegradation of component hydrocarbons may occur (Aelion and Bradley 1991).Results indicated that biodegradation might be limited by the available nitrogen in the ecosystem.Samples from a contaminated aquifer have also been shown to degrade aromatic JP-4 componentsunder denitrifying (anaerobic) conditions, although at a very low rate (Hutchins et al. 1991).5.3.2.3 Sediment and SoilConsiderable evidence exists to indicate that jet fuel is biodegraded in the soil. This is not unexpectedsince several components of jet fuel are known to be degraded by soil microorganisms. Application ofshale-derived JP-4 to model soil core ecosystems resulted in increased production of carbon dioxide in the system (Air Force 1981e, 1982c). Increased activity following addition of JP-4 to soil has beenassociated with increased microbial growth and decreased hydrocarbon residues (Song and Bartha1990; Wang and Bartha 1990). The likely reason for this increase was increased activity ofmicroorganisms that use the JP-4 component hydrocarbons. Laboratory comparisons of soilcontaminated with JP-4 and uncontaminated soil showed that both degraded JP-4 hydrocarbons underaerobic conditions when nitrogen, phosphorus, and trace minerals were added (Yong and Mourato1987). The uncontaminated soil had a lag time before biodegradation was initiated, whereas thecontaminated soil showed immediate initiation of biodegradation. These data indicate the importanceof microbial adaptation to biological breakdown of jet fuel in soil. Additional experiments innonaerated soils showed that biodegradation of JP-4 hydrocarbons occurred under these conditions butwas considerably reduced compared to degradation in aerated soils. Other studies have supported theevidence that most JP-4 degradation is aerobic (Song and Bartha 1990). In these experiments,decreased biodegradation in subsurface soils was associated with decreased oxygen. Model soil coreecosystems composed of contaminated soil taken from the site of a JP-4 spill were tested forbiodegradation under a range of soil and water content conditions (Coho 1990). Two columns werevented with a mix of oxygen and nitrogen, and a control column was vented with nitrogen only. Theventing rates were kept low to reduce losses through volatilization. An average of 44% of the originalmass of JP-4 present in the soil (3,560 mg/kg moist soil; 4,590 mg/kg dry soil) was removed over theSl-89-day experimental period. Biodegradation accounted for 93% of the total removed andvolatilization accounted for 7%. The maximum rate of biodegradation, 14.3 mg/kg moist soil/day,occurred at a soil/water content of 72% saturation. The average rate of degradation due to microbialactivity was about 10.6 mg/kg moist soil/day. Biodegradation of JP-4 has also been shown to beaffected by soil type, temperature, and jet fuel concentration (Song et al. 1990). Biodegradation wasgreater in clay soil than sand or loam. The optimum temperature was 27 °C, with decreaseddegradation at higher and lower temperatures. The half-life of JP-4 in clay at 27 ºC was 3.5 weeks.Bioremediation treatment to increase the oxygen and mineral content of the soil decreased the half-lifeto 1.7 weeks. Some products of JP-4 metabolism appeared to be inhibitory to the microbiota, resultingin slightly decreased biodegradation rates at higher fuel concentrations (Song and Bartha 1990). At aconcentration of 50 mg/g dry soil, 85% of the JP-4 had disappeared in 4 weeks, and with aconcentration of 135 mg/g dry soil, 75% was degraded in 4 weeks. The components of JP-4 fuelfound to be biodegradable in soil were tridecane, tetradecane and pentadecane, but undecane,dodecane and hexadecane were resistant to aerobic biodegradation (Dean-Ross 1993). Althoughanaerobic biodegradation of components in JP-4 fuel is slower than aerobic biodegradation, anaerobic biodegradation of JP-4 fuel was observed in sediments. The carbon mineralization rate was mostfavorable at an added nitrate concentration of approximately 1 mmol and a pH of 6-7 (Bradley et al.1992).5.4 LEVELS MONITORED OR ESTIMATED IN THE ENVIRONMENTJP-4 and JP-7 consist of various hydrocarbon components such as benzene, toluene, and xylene.These components can be measured in high concentrations in air, water, and soil.5.4.1 AirJP-4 and JP-7 enter the atmosphere through various mechanisms such as evaporation of spills,vaporization in loading and unloading operations, and burning in engines. JP-4 was detected insamples in a closed aircraft shelter that housed F-4 aircraft (Air Force 1981h). The JP-4concentrations in the air ranged from 533 mg/m3(in the area of the shelter) to 1,160 mg/m3(in thevicinity of the refueler technician).5.4.2 WaterBetween 1986 and 1988, a hydrocarbon plume of JP-4 was discovered floating on the water table atthe Federal Aviation Administration (FAA) Technical Center (Atlantic County, New Jersey) after JP-4fuel contamination was discovered (EPA 1990b). The organic contaminants benzene, toluene, andnaphthalene (identical to the components in jet fuel) were detected in groundwater samples atconcentrations of 4,000, 3,100, and 1,000 ppb, respectively. The total volume of jet fuel-contaminatedgroundwater at the site was estimated to be 13.3 million gallons. In October of 1975, JP-4 wasdetected in water samples taken from the Defense Fuel Supply Center (Charleston, South Carolina) ata depth of 15 feet and at distances of 2.5 feet, 40 feet, and 50 feet from an 83,000-gallon fuel spill(Talts et al. 1977). From a distance of 25 feet, pure fuel was measured, while a concentration of33 µg/mL was measured at 40 feet, and 22 µg/mL was measured at 50 feet.Groundwater contamination was reported in East Bay Township, Michigan, in the vicinity of a U.S.Coast Guard Air Station (Twenter et al. 1985). The amount of toluene detected in groundwatersamples was 74 µg/L. This concentration may possibly be attributed to JP-4 contamination, although there were many other organics used on the base that could be sources of major groundwatercontamination.5.4.3 SoilJP-4 as determined by total hydrocarbons in soil samples was detected at Robins Air Force Base(Georgia) at a depth of 1 meter in the soil around the site of a 20-year-old JP-4 spill; concentrationsranged from <0.1 µg/L at an approximate distance of 90 meters from the spill site to 180,000 µg/Lwithin the vicinity of the fuel spill (EPA 1988a). Soil gas samples taken at 2 meters revealed aconcentration ranging from <0.05 µg/L at an approximate distance of 50 meters from the fuel spill to aconcentration of 310,000 µg/L in the vicinity of the fuel spill. Soil contamination of JP-4hydrocarbons was also measured at the FAA Technical Center (Atlantic County, New Jersey); themaximum petroleum hydrocarbon concentration detected in surface soils was 284 ppm and themaximum concentration in subsurface soils was 18,500 ppm (EPA 1990b).5.4.4 Other Environmental MediaNo data were located that discussed concentrations of JP-4 or JP-7 in other environmental media suchas food, fish and shellfish, or terrestrial plants and animals.5.5 GENERAL POPULATION AND OCCUPATIONAL EXPOSUREThe National Occupational Exposure Survey, conducted by NIOSH between 1981 and 1983, estimatedthat 4,866 employees were exposed to JP-4 in the workplace (NOES 1990). No workplace exposuredata were available for JP-7.General population exposure to JP-4 and JP-7 is likely. However, exposure would be limited topopulations living on or near Air Force bases where JP-4 and JP-7 are used in aircraft. Thesepopulations could be exposed to JP-4 and JP-7 from hydrocarbon release into air from aircraft orgroundwater contaminated with spilled JP-4 or JP-7. Air Force base workers engaged in fuel cell maintenance operations such as defueling and fuelingaircraft and cleaning jet fuel spills are exposed to higher levels of JP-4 and JP-7 than those to whichthe general population is exposed (Bishop 1982). Other workers that are exposed to higher levels ofJP-4 and JP-7 than the general population are component testers, engine testers, and mechanics (Knaveet al. 1978). Maintenance workers who monitor fuel storage tanks may be exposed to jet fuels byinhalation or dermal exposure to draining water (due to condensation) from the fuel tanks (NIOSH1989). Potentially high exposure through inhalation and dermal route may also occur for workers inpetroleum plants that manufacture JP-4 and JP-7. Populations living on or very near Air Force bases,populations living near hazardous waste disposal sites for JP-4 and JP-7, and populations exposed as aresult of spills and leaks that may occur during storage, transfer, and use of the these jet fuels arepotentially exposed to higher levels of JP-4 and JP-7 than those to which the general population isexposed. However, data correlating the levels of these fuels or their biomarkers in body tissues andfluids (e.g., blood) with levels of exposure among these groups of population were not located.Military pilots have a potentially higher risk of exposure to JP-4 and JP-7 than the general population.The concentration of JP-4 vapors sampled from the cockpit of an F-4 was 1,110 mg/m3 (Air Force1981h).5.7 ADEQUACY OF THE DATABASESection 104(i)(5) of CERCLA, as amended, directs the Administrator of ATSDR (in consultation withthe Administrator of EPA and agencies and programs of the Public Health Service) to assess whetheradequate information on the health effects of JP-4 and JP-7 is available. Where adequate informationis not available, ATSDR, in conjunction with NTP, is required to assure the initiation of a program ofresearch designed to determine the health effects (and techniques for developing methods to determinesuch health effects) of JP-4 and JP-7.The following categories of possible data needs have been identified by a joint team of scientists fromATSDR, NTP, and EPA. They are defined as substance-specific informational needs that, if met,would reduce or eliminate the uncertainties of human health assessment. This definition should not beinterpreted to mean that all data needs discussed in this section must be filled. In the future, the identified data needs will be evaluated and prioritized, and a substance-specific research agenda maybe proposed.5.7.1 Identification of Data NeedsPhysical and Chemical Properties. The values for many of the physicochemical parameters(e.g., KowKocand Henry’s law constants) needed to model the fate and transport processes of JP-4 andJP-7 in the environment have not been determined. However, since these fuels are complex mixturesof hydrocarbons with small amounts of non-hydrocarbon additives, their behavior in the environmentis determined by both the characteristics of the mixture and the characteristics of the individualcomponents, making modeling based on physical and chemical properties difficult.Production, Import/Export, Use, and Release and Disposal. Current production andimport/export data are lacking and would aid in determining how pervasive the risk of exposure toJP-4 and JP-7 is to the general population. The uses of JP-4 and JP-7 are restricted to military aircraft(Air Force 1989b; IARC 1989). The primary releases to the environment come from in-flightjettisoning of fuel and from leaks and spills during storage, transfer, and use (IARC 1989; Talts et al.1977; Twenter et al. 1985). Several disposal methods have been proposed, tested, and/or used (Elliotand DePaoli 1990; EPA 1990b; NIOSH 1989). However, data are needed on the risk posed by pastdisposal methods and improper disposal of the fuels.According to the Emergency Planning and Community Right-to-Know Act of 1986, 42 U.S.C. Section11023, industries are required to submit chemical release and off-site transfer information to the EPA.The Toxics Release Inventory (TRI), which contains this information for 1992, became available inMay of 1994. This database will be updated yearly and should provide a list of industrial productionfacilities and emissions. However, since JP-4 and JP-7 are not reported under SARA Section 313,there are no data in the TRI.Environmental Fate. The environmental fate of JP-4 has been studied extensively by the AirForce, EPA, and independent researchers. No data were located on the environmental fate of JP-7,although it can be assumed to behave in a manner similar to JP-4. Most JP-4 jettisoned in theatmosphere probably reacts photochemically to form ozone and particulates (Air Force 1981b, 1981e).Some of the fuel components or reactant products are probably transported by wind currents. The primary fate process for JP-4 in water is volatilization, although some biodegradation and partitioningto sediment may occur (Air Force 1983f, 1988b; EPA 1985). The primary fate process for JP-4spilled to soil is biodegradation (Air Force 1982c; Coho 1990; Song and Bartha 1990). A smallfraction is likely to volatilize and some components may bind to soil particles. JP-4 that spills orleaks to soil migrates both horizontally and vertically, but that migration does not seem to be dueprimarily to leaching. Information on the degradation products of some of the components of JP-4 andJP-7 may be found in ATSDR profiles on benzene (ATSDR 1991a), toluene (ATSDR 1990), totalxylenes (ATSDR 1991c), and polycyclic aromatic hydrocarbons (ATSDR 1991b). Components of jetfuel that migrate through the soil may contaminate groundwater (EPA 1990b; Talts et al. 1977). Moreinformation on chemical and light-mediated reactions of jet fuel components would help in assessingthe persistence of jet fuel hydrocarbons in water and soil. In addition, more studies on theenvironmental fate of jet fuel under various water and soil conditions might provide insight into thevariations in the fate of components that have been found under varying environmental conditions.Specifically, data pertaining to the interaction of JP-4 or JP-7 with various types of soils, includingclays, sands, and mixtures would be useful, in order to determine horizontal and vertical migrationpatterns for assessing groundwater contamination in the vicinity of Air Force bases and hazardouswaste sites. This information could also help in determining which jet fuel components persist in theenvironment and under what conditions.Bioavailability from Environmental Media. There are no data on the absorption of JP-4 orJP-7 by the inhalation, oral, or dermal routes. However, several of the components of these fuels areknown to be absorbed. For more information on absorption of individual components (e.g., benzene,xylene, toluene), see the ATSDR toxicological profiles on these compounds.Food Chain Bioaccumulation. There are no data on the bioaccumulation or biomagnification ofJP-4 or JP-7 in plants, aquatic organisms, or animals. Studies on the bioaccumulation of JP-4 andJP-7 are needed for plants, animals, and aquatic organisms, especially shellfish which, historically,have exhibited sensitivity to hydrocarbons. Data on a similar jet fuel, JP-8, suggest thatbioaccumulation and biomagnification are low (Klein and Jenkins 1983). The mixtures are expected toseparate into the individual components in the environment and these components are expected behaveindependently and differently in terms of their ability to accumulate in the food chain. Forinformation on the bioaccumulation of the different components of JP-4 and JP-7 (e.g., benzene,xylene, toluene, ethylbenzene), see the ATSDR toxicological profiles for these compounds. Exposure Levels in Environmental Media. Some information exists on the levels of JP-4 andJP-7 in the air in closed buildings where the fuel is used (Air Force 1981h). Limited information wasalso located on levels in water and soil following spills or leaks (EPA 1988a, 1990b; Talts et al.1977). No data were located on levels of jet fuels or component hydrocarbons in food, fish andshellfish, or terrestrial animals and plants. More data on levels in all environmental media are neededto fully assess the extent of exposure for populations with a high probability of exposure to jet fuels ortheir component hydrocarbons.Exposure Levels in Humans. Certain populations are known to have a higher risk of exposureto JP-4, JP-7, and/or their component hydrocarbons. These are workers who manufacture or use thefuel; people living or working on Air Force bases where the fuel is stored and used; and populationsliving or working in the vicinity of a spill, leak, or dump site (Air Force 1981h; Bishop 1982; NIOSH1989). More data are needed to assess the approximate levels of intermediate and chronic exposurefor these populations.Exposure Registries. No exposure registries for JP-4 and JP-7 were located. Components ofJP-4 and JP-7 will be considered for inclusion in the National Exposure Registry in the future. Theinformation that is amassed in the National Exposure Registry facilitates the epidemiological researchneeded to assess adverse health outcomes that may be related to exposure to these compounds.5.7.2 Ongoing StudiesInvestigations into the bioremediation of sites contaminated with jet fuels are providing informationon the biodegradation of these compounds. Bioremediation studies are being conducted by theDepartment of the Interior, U.S. Geological Survey at a spill site in Charleston, South Carolina(FEDRIP 1994).As part of the Third National Health and Nutrition Evaluation Survey (NHANES III), theEnvironmental Health Laboratory Sciences Division of the Center for Environmental Health andInjury Control, Centers for Disease Control and Prevention, will be analyzing human blood samplesfor certain components of JP-4 and JP-7 and other volatile organic compounds. These data will give anindication of the frequency of occurrence and background levels of these compounds in the generalpopulation.
Súgó
A téma zárva.
Hapcihológia. 
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