Jet Propulsion Fuel 8 Research Articles

Thermodynamics study of biokerosene from coconut and palm kernel oils and JP-8 aircraft fuels in the gas phase by the DFT method.

In this work, we performed a theoretical density functional theory (DFT) and semi-empirical (PM3) analysis to calculate thermodynamic properties of biokerosene from coconut and palm kernel oils, Jet Propulsion Fuel 8 (JP-8), and mixtures of these fuels. All simulations were performed in thermal equilibrium and for a temperature range of 0.5-1500K, considering the canonical ensemble model. We predicted the thermal properties energy, enthalpy, enthalpy change, Gibbs free energy, entropy, and specific heat at constant pressure with respect to temperature. In addition, we compared the performances of the DFT functional hybrid B3LYP and the basis set 6-311++G(d,p) and PM3 methods, in order to determine their accuracy for thermodynamic predictions relating to the fuels. Calculations for combustion enthalpy were carried out using the following methods: B3LYP/6-311++G(d,p), B3LYP/6-31+G(d), CBS-QB3, G3, G4, and G3/G4. The results showed good agreement with measured values, indicating that DFT may be a good method to calculate and predict thermodynamic properties of the combustion reactions of kerosene and biokerosene.

Volatile Organic Compounds in Blood as Biomarkers of Exposure to JP-8 Jet Fuel Among US Air Force Personnel.

This study aimed to evaluate blood volatile organic compound (VOC) levels as biomarkers of occupational jet propulsion fuel 8 (JP-8) exposure while controlling for smoking. Among 69 Air Force personnel, post-shift blood samples were analyzed for components of JP-8, including ethylbenzene, toluene, o-xylene, and m/p-xylene, and for the smoking biomarker, 2,5-dimethylfuran. JP-8 exposure was characterized based on self-report and measured work shift levels of total hydrocarbons in personal air. Multivariate regression was used to evaluate the relationship between JP-8 exposure and post-shift blood VOCs while controlling for potential confounding from smoking. Blood VOC concentrations were higher among US Air Force personnel who reported JP-8 exposure and work shift smoking. Breathing zone total hydrocarbons was a significant predictor of VOC blood levels, after controlling for smoking. These findings support the use of blood VOCs as a biomarker of occupational JP-8 exposure.

Volatile Organic Compounds Measured in Blood as a Measure of Personal Exposure to Jet Fuel in Air Force Personnel

Jet propulsion fuel 8 (JP8) is the main fuel used by the US Air Force (USAF). Exposure to JP8 has previously been characterized by measuring volatile organic compounds (VOCs) in exhaled breath and ...

Urinary polycyclic aromatic hydrocarbon (OH-PAH) metabolite concentrations and the effect of GST polymorphisms among US Air Force personnel exposed to jet fuel.

To evaluate the association between inhalation exposure to jet propulsion fuel 8 (JP-8) and urinary metabolites among US Air Force (USAF) personnel, and investigate the role of glutathione S-transferase polymorphisms. Personal air samples were collected from 37 full-time USAF personnel during 4 consecutive workdays and analyzed for JP-8 constituents and total hydrocarbons. Pre- and postshift urine samples were collected each day and analyzed for polycyclic aromatic hydrocarbon urinary metabolites. Work shift exposure to total hydrocarbons was significantly associated with postshift urinary 1-naphthol (β = 0.17; P = <0.0001), 2-naphthol (β = 0.09; P = 0.005), and 2-hydroxyfluorene concentrations (β = 0.08; P = 0.006), and a significant gene-environment interaction was observed with glutathione S-transferase mu-1. USAF personnel experience inhalation exposure to JP-8, which is associated with absorption of JP-8 constituents while performing typical job-related tasks, and in our data the glutathione S-transferase mu-1 polymorphism was associated with differential metabolism of naphthalene.

Exposure to Low Levels of Jet-Propulsion Fuel Impairs Brainstem Encoding of Stimulus Intensity

Jet propulsion fuel-8 (JP-8) is a kerosene-based fuel that is used in military jets. The U.S. Armed Services and North Atlantic Treaty Organization countries adopted JP-8 as a standard fuel source and the U.S. military alone consumes more than 2.5 billion gallons annually. Preliminary epidemiologic data suggested that JP-8 may interact with noise to induce hearing loss, and animal studies revealed damage to presynaptic sensory cells in the cochlea. In the current study, Long-Evans rats were divided into four experimental groups: control, noise only, JP-8 only, and JP-8 + noise. A subototoxic level of JP-8 was used alone or in combination with a nondamaging level of noise. Functional and structural assays of the presynaptic sensory cells combined with neurophysiologic studies of the cochlear nerve revealed that peripheral auditory function was not affected by individual exposures and there was no effect when the exposures were combined. However, the central auditory nervous system exhibited impaired brainstem encoding of stimulus intensity. These findings may represent important and major shifts in the theoretical framework that governs current understanding of jet fuel and/or jet fuel + noise-induced ototoxicity. From an epidemiologic perspective, results indicate that jet fuel exposure may exert consequences on auditory function that may be more widespread and insidious than what was previously shown. It is possible that a large population of military personnel who are suffering from the effects of jet fuel exposure may be misidentified because they would exhibit normal hearing thresholds but harbor a “hidden” brainstem dysfunction.

Postural Sway and Exposure to Jet Propulsion Fuel 8 Among US Air Force Personnel

To determine whether short-term jet propulsion fuel 8 (JP-8) exposure is associated with balance measurements in JP-8-exposed air force personnel. As part of a larger neuroepidemiology study, balance tasks were completed by JP-8-exposed individuals (n = 37). Short-term JP-8 exposure was measured using personal breathing zone levels and urinary biomarkers. Multivariate linear regression analyses were conducted to examine the relationship between workday JP-8 exposure and postural sway. Balance control decreased as the task became more challenging. Workday exposure to JP-8, measured by either personal air or urinary metabolite levels, was not significantly related to postural sway. Increases in workday postural sway were associated with demographic variables, including younger age, being a current smoker, and higher body mass index. Results suggest that short-term workday JP-8 exposure does not significantly contribute to diminished balance control.

Detection of DNA damage in workers exposed to JP-8 jet fuel

The genotoxicity of jet propulsion fuel 8 (JP-8) was assessed in the leukocytes of archived blood specimens from U.S. Air Force personnel using the comet assay. No differences in mean comet assay measurements were found between low, moderate, and high exposure groups before or after a 4h work shift.Before the work shift, mean tail DNA and mean tail (Olive) moment increased as the concentration of benzene measured in end-exhaled breath increased, indicating that prior environmental or work-related exposures to benzene produced DNA damage. The number of cells with highly damaged DNA decreased as the pre-shift benzene concentration in breath increased. It is not clear why the decrease is occurring.Mean tail DNA and mean tail (Olive) moment decreased as the concentrations of benzene and naphthalene measured in breath immediately after the work shift increased. These inverse relationships may reflect a slower rate of absorption or a faster rate of expiration of benzene in the lung.The number of cells with highly damaged DNA increased as the concentration of urinary (2-methoxyethoxy)acetic acid (MEAA) increased. This relationship was not seen in urinary MEAA adjusted for creatinine. MEAA is a metabolite of the deicing agent 2-(2-methoxyethoxy)ethanol contained in JP-8. MEAA or a component of JP-8 correlated with MEAA may have a toxic effect on DNA.

Characterization of Inhalation Exposure to Jet Fuel among U.S. Air Force Personnel

Jet propulsion fuel-8 (JP-8) is the primary jet fuel used by the US military, collectively consuming ~2.5 billion gallons annually. Previous reports suggest that JP-8 is potentially toxic to the immune, respiratory, and nervous systems. The objectives of this study were to evaluate inhalation exposure to JP-8 constituents among active duty United States Air Force (USAF) personnel while performing job-related tasks, identify significant predictors of inhalation exposure to JP-8, and evaluate the extent to which surrogate exposure classifications were predictive of measured JP-8 exposures. Seventy-three full-time USAF personnel from three different air force bases were monitored during four consecutive workdays where personal air samples were collected and analyzed for benzene, ethylbenzene, toluene, xylenes, total hydrocarbons (THC), and naphthalene. The participants were categorized a priori into high- and low-exposure groups, based on their exposure to JP-8 during their typical workday. Additional JP-8 exposure categories included job title groups and self-reported exposure to JP-8. Linear mixed-effects models were used to evaluate predictors of personal air concentrations. The concentrations of THC in air were significantly different between a priori exposure groups (2.6 mg m(-3) in high group versus 0.5 mg m(-3) in low, P < 0.0001), with similar differences observed for other analytes in air. Naphthalene was strongly correlated with THC (r = 0.82, P < 0.0001) and both were positively correlated with the relative humidity of the work environment. Exposures to THC and naphthalene varied significantly by job categories based on USAF specialty codes and were highest among personnel working in fuel distribution/maintenance, though self-reported exposure to JP-8 was an even stronger predictor of measured exposure in models that explained 72% (THC) and 67% (naphthalene) of between-worker variability. In fact, both self-report JP-8 exposure and a priori exposure groups explained more between-worker variability than job categories. Personal exposure to JP-8 varied by job and was positively associated with the relative humidity. However, self-reported exposure to JP-8 was an even stronger predictor of measured exposure than job title categories, suggesting that self-reported JP-8 exposure is a valid surrogate metric of exposure when personal air measurements are not available.

Urinary biomarkers of occupational jet fuel exposure among air force personnel

There is a potential for widespread occupational exposure to jet fuel among military and civilian personnel. Urinary metabolites of naphthalene have been suggested for use as short-term biomarkers of exposure to jet fuel (jet propulsion fuel 8 (JP8)). In this study, urinary biomarkers of JP8 were evaluated among US Air Force personnel. Personnel (n=24) were divided a priori into high, moderate, and low exposure groups. Pre- and post-shift urine samples were collected from each worker over three workdays and analyzed for metabolites of naphthalene (1- and 2-naphthol). Questionnaires and breathing-zone naphthalene samples were collected from each worker during the same workdays. Linear mixed-effects models were used to evaluate the exposure data. Post-shift levels of 1- and 2-naphthol varied significantly by a priori exposure group (levels in high group>moderate group>low group), and breathing-zone naphthalene was a significant predictor of post-shift levels of 1- and 2-naphthol, indicating that for every unit increase in breathing-zone naphthalene, there was an increase in naphthol levels. These results indicate that post-shift levels of urinary 1- and 2-naphthol reflect JP8 exposure during the work-shift and may be useful surrogates of JP8 exposure. Among the high exposed workers, significant job-related predictors of post-shift levels of 1- and 2-naphthol included entering the fuel tank, repairing leaks, direct skin contact with JP8, and not wearing gloves during the work-shift. The job-related predictors of 1- and 2-naphthol emphasize the importance of reducing inhalation and dermal exposure through the use of personal protective equipment while working in an environment with JP8.

(2-Methoxyethoxy)acetic acid: a urinary biomarker of exposure for jet fuel JP-8

To demonstrate the utility of the urinary metabolite (2-methoxyethoxy)acetic acid (MEAA) as a biomarker of exposure. 2-(2-methoxyethoxy)ethanol [diethylene glycol monomethyl ether] is an anti-icing agent used in the formulation of JP-8, and it is added at a known uniform 0.1% (v/v) concentration to each batch lot. JP-8 is a kerosene-based fuel containing different compounds that vary in the content of every batch/lot of fuel; thus, MEAA has the potential to be a more specific and a consistent quantitative biomarker for JP-8 exposure. MEAA was used to measure exposure of jet propulsion fuel 8 (JP-8) in United States Air Force (USAF) personnel working at six airbases within the United States. Post-shift urine specimens from various personnel including high (n = 98), moderate (n = 38), and low (n = 61) exposure workgroup categories were collected and analyzed by a gas chromatographic-mass spectrometric test method. The three exposure groups were evaluated for the number per group positive for MEAA, and a statistical analysis consisted of pair-wise t-tests for unequal variances was used to test for the differences in mean MEAA concentrations between the exposure groups. The number of samples detected as positive for MEAA exposure, that is, those above the test method's limit of detection (LOD = 0.1 μg/ml), were 92 (93.9%), 13 (34.2%), and 2 (3.3%) for the high, moderate, and low exposure workgroup categories, respectively. The mean urinary MEAA level was significantly greater in the high exposure category (6.8 μg/ml), compared to the moderate (0.42 μg/ml) and the low (0.07 μg/ml) exposure categories. The maximum concentration of urinary MEAA was 110 μg/ml for the high exposure category, while 4.8 μg/ml and 0.2 μg/ml maximum levels were found in the moderate and low exposure categories, respectively. This study demonstrated that urinary MEAA can be used as an accurate biomarker of exposure for JP-8 workers and clearly distinguished the differences in JP-8 exposure by workgroup category.

Characterization of Jet Fuel Inhalation Exposure and Urinary Metabolites in U.S. Air Force Personnel

ISEE-0491 Background and Objective: Jet propulsion fuel-8 (JP-8) is the primary jet fuel used by the U.S. military, collectively consuming about 2.53 billion gallons annually. Previous reports suggest that JP-8 is potentially toxic to the immune, respiratory, and nervous systems. The objectives of this study were to evaluate inhalation exposure to JP-8 as well as absorption of JP-8 constituents among U.S. Air Force (USAF) personnel while performing job-related tasks. Methods: Seventy-three full-time USAF personnel from three active bases were categorized a priori as having low (n = 35) or high (n = 38) exposure to JP-8 based on job title and tasks. Personal air samples were collected from each participant during four consecutive workdays using air pumps and sorbent tubes. Using gas chromatography/mass spectrometry, charcoal sorbent tubes were analyzed for benzene, ethylbenzene, toluene, xylenes, and total hydrocarbons (THC) while Chromosorb® tubes were analyzed for naphthalene. Pre- and post-shift urine samples were also collected from each worker each day and analyzed for 1- and 2- naphthols, 2-, 3-, and 9-hydroxyflourene, 1-, 2-, 3-, and 4-hydroxyphenanthrene, and 1-hydroxypyrene. Linear mixed-effects models were used to explore the association between inhalation exposure and post-shift urinary metabolites, adjusting for creatinine and pre-shift urinary concentrations. Results: THC air concentrations were significantly different between the exposure groups (2.6 vs. 0.5 mg/m3, P < 0.0001). Similar differences were observed for the other analytes measured in air. Among the high exposure group, post-shift urinary 1- and 2-naphthol levels were significantly higher than pre-shift levels (both P < 0.05). Inhalation exposure to THC was significantly associated with post-shift urinary 1-naphthol (β = 0.21, P < 0.0001), 2-naphthol (β = 0.11, P = 0.0006) and 2-hydroxyflourene levels (β = 0.08, P = 0.005). Naphthalene air concentrations displayed similar significant associations with post-shift urinary 1-naphthol (β = 0.26, P < 0.0001) and 2-naphthol levels (β = 0.13, P < 0.0001). Conclusion: USAF personnel experience inhalation exposure to JP-8 which is associated with absorption of JP-8 constituents while performing normal job-related tasks.

Puffing Frequency and Soot Extinction Correlation in JP-8 and Heptane Pool Fires

A new approach for characterizing puffing frequency was established by performing total extinction measurements on pool fires of JP-8 (Jet Propulsion Fuel 8) and heptane using a multiple beam extinction experiment. A maximum entropy method (MEM) was applied to extract a characteristic extinction frequency that was found to correlate well with puffing frequency. The measured extinction frequency for both flames was found to have some variation with height, though this is small. The amplitude of the frequency of the measured oscillations was found to be higher for JP-8 than for heptane, and became constant one diameter above the fuel pan for both flames. The variance of total extinction in the JP-8 and heptane pool fires was approximately 20% and 17%, respectively. Correlation statistics between the various extinguished beams reveal an increase in axi-symmetry of the instantaneous oscillations with height above the pool.

Serum Profiling of Rat Dermal Exposure to JP-8 Fuel Reveals an Acute-Phase Response

ABSTRACTDermal exposure to JP-8 petroleum jet fuel leads to toxicological responses in humans and rodents. Serum profiling is a molecular analysis of changes in the levels of serum proteins and other molecules in response to changes in physiology. This present study utilizes serum profiling approaches to examine biomolecular changes in the sera of rats exposed to dermal applications of JP-8 (jet propulsion fuel-8). Using gel electrophoresis and electrospray ionization (ESI) mass spectrometry (MS), levels of serum proteins as well as low-mass constituents were found to change after dermal exposures to JP-8. The serum protein levels altered included the acute-phase response proteins haptoglobin, ceruloplasmin, α1-inhibitor III, and apolipoprotein A-IV. Haptoglobin levels increased after a 1-day JP-8 dermal exposure and continued to increase through 7 days of exposure. Ceruloplasmin levels increased after 5 days of exposure. Serum α1-inhibitor III was reduced after a 1-day exposure and the depletion continued after 7 days of exposure. Apolipoprotein A-IV increased after a 1-day exposure and then returned to basal levels after 3- and 5-day exposures of JP-8. Levels of the acute-phase protein α2-macroglobulin were found to not vary over these time course studies. Using ESI-MS analysis directly on the sera from rats exposed to dermal JP-8, low-mass sera constituents were found to correlate with control (acetone) or JP-8 exposure.

Repeated Aerosol-vapor JP-8 Jet Fuel Exposure Affects Neurobehavior and Neurotransmitter Levels in a Rat Model

Four groups of Fischer Brown Norway hybrid rats were exposed for 5, 10, 15, or 20 d to aerosolized-vapor jet propulsion fuel 8 (JP-8) compared to freely moving (5 and 10-d exposures) or sham-confined controls (15 and 20-d exposures). Behavioral testing utilized the U.S. Environmental Protection Agency Functional Observational Battery. Exploratory ethological factor analysis identified three salient factors (central nervous system [CNS] excitability, autonomic 1, and autonomic 2) for use in profiling JP-8 exposure in future studies. The factors were used as dependent variables in general linear modeling. Exposed animals were found to engage in more rearing and hyperaroused behavior compared to controls, replicating prior JP-8 exposure findings. Exposed animals also showed increasing but rapidly decelerating stool output (autonomic 1), and a significant increasing linear trend for urine output (autonomic 2). No significant trends were noted for either of the control groups for the autonomic factors. Rats from each of the groups for each of the time frames were randomly selected for tissue assay from seven brain regions for neurotransmitter levels. Hippocampal DOPAC was significantly elevated after 4-wk JP-8 exposure compared to both control groups, suggesting increased dopamine release and metabolism. Findings indicate that behavioral changes do not appear to manifest until wk 3 and 4 of exposure, suggesting the need for longitudinal studies to determine if these behaviors occur due to cumulative exposure, or due to behavioral sensitization related to repeated exposure to aerosolized-vapor JP-8.

Gene Expression and Target Tissue Dose in the Rat Epidermis after Brief JP-8 and JP-8 Aromatic and Aliphatic Component Exposures

Exposures of jet propulsion fuel 8 (JP-8) to human and laboratory animal skin have resulted in skin irritation. JP-8 is a mixture of aromatic and aliphatic hydrocarbons, which in some cases have also been shown to be irritating to the skin. In an attempt to determine if aromatic or aliphatic components could mimic the JP-8-induced gene expression response, we exposed rats to JP-8, undecane (UND), tetradecane (TET), trimethylbenzene (TMB), and dimethylnaphthalene (DMN) for 1 h and examined the epidermis to characterize the gene expression response. We also measured the concentrations of the JP-8 components in the epidermis with gas chromatography/mass spectrometry after 1-h exposures to JP-8 and pure components to determine if differences in potency could be identified. Changes in gene expression, compared to sham treatment, were studied with microarray techniques and analyzed for changes in gene ontology categories. UND and TMB exposures caused the greatest number of changes in transcript levels compared to DMN and TET. When only the specific functional and signaling pathways that were changed by JP-8 were considered, these pathways were nearly all activated by the components, but to different extents. After pure component exposures, the epidermal concentrations of the components showed no significant differences, although the differences in magnitude of either total or pathway-specific gene expression differed by a factor of 10-fold. We conclude that no single component that we studied mimicked the gene expression resulting from the JP-8 exposure but that UND had the most similar responses. These data suggest that there are differences in potency between the four components studied.

PBTK Modeling Demonstrates Contribution of Dermal and Inhalation Exposure Components to End-Exhaled Breath Concentrations of Naphthalene

BackgroundDermal and inhalation exposure to jet propulsion fuel 8 (JP-8) have been measured in a few occupational exposure studies. However, a quantitative understanding of the relationship between external exposures and end-exhaled air concentrations has not been described for occupational and environmental exposure scenarios.ObjectiveOur goal was to construct a physiologically based toxicokinetic (PBTK) model that quantitatively describes the relative contribution of dermal and inhalation exposures to the end-exhaled air concentrations of naphthalene among U.S. Air Force personnel.MethodsThe PBTK model comprised five compartments representing the stratum corneum, viable epidermis, blood, fat, and other tissues. The parameters were optimized using exclusively human exposure and biological monitoring data.ResultsThe optimized values of parameters for naphthalene were a) permeability coefficient for the stratum corneum 6.8 × 10−5 cm/hr, b) permeability coefficient for the viable epidermis 3.0 × 10−3 cm/hr, c) fat:blood partition coefficient 25.6, and d) other tissue:blood partition coefficient 5.2. The skin permeability coefficient was comparable to the values estimated from in vitro studies. Based on simulations of workers’ exposures to JP-8 during aircraft fuel-cell maintenance operations, the median relative contribution of dermal exposure to the end-exhaled breath concentration of naphthalene was 4% (10th percentile 1% and 90th percentile 11%).ConclusionsPBTK modeling allowed contributions of the end-exhaled air concentration of naphthalene to be partitioned between dermal and inhalation routes of exposure. Further study of inter- and intraindividual variations in exposure assessment is required to better characterize the toxicokinetic behavior of JP-8 components after occupational and/or environmental exposures.

Effects of Brief Cutaneous JP-8 Jet Fuel Exposures on Time Course of Gene Expression in the Epidermis

The jet fuel jet propulsion fuel 8 (JP-8) has been shown to cause an inflammatory response in the skin, which is characterized histologically by erythema, edema, and hyperplasia. Studies in laboratory animal skin and cultured keratinocytes have identified a variety of changes in protein levels related to inflammation, oxidative damage, apoptosis, and cellular growth. Most of these studies have focused on prolonged exposures and subsequent effects. In an attempt to understand the earliest responses of the skin to JP-8, we have investigated changes in gene expression in the epidermis for up to 8 h after a 1-h cutaneous exposure in rats. After exposure, we separated the epidermis from the rest of the skin with a cryotome and isolated total mRNA. Gene expression was studied with microarray techniques, and changes from sham treatments were analyzed and characterized. We found consistent twofold increases in gene expression of 27 transcripts at 1, 4, and 8 h after the beginning of the 1-h exposure that were related primarily to structural proteins, cell signaling, inflammatory mediators, growth factors, and enzymes. Analysis of pathways changed showed that several signaling pathways were increased at 1 h and that the most significant changes at 8 h were in metabolic pathways, many of which were downregulated. These results confirm and expand many of the previous molecular studies with JP-8. Based on the 1-h changes in gene expression, we hypothesize that the trigger of the JP-8-induced, epidermal stress response is a physical disruption of osmotic, oxidative, and membrane stability which activates gene expression in the signaling pathways and results in the inflammatory, apoptotic, and growth responses that have been previously identified.

Dermal absorption and penetration of jet fuel components in humans

Jet propulsion fuel 8 (JP-8) is the largest source of chemical exposures on military bases. Dermal exposure to JP-8 has been investigated in vitro using rat or pig skin, but not in vivo in humans. The purpose of this study was to investigate the absorption and penetration of aromatic and aliphatic components of JP-8 in humans. A surface area of 20 cm 2 was delineated on the forearms of human volunteers and 1 ml of JP-8 was applied to the skin. Tape-strip samples were collected 30 min after application. Blood samples were taken before exposure ( t = 0 h), after exposure ( t = 0.5 h), and every 0.5 h for up to 4 h past exposure. The tape-strip samples showed evidence of uptake into the skin for all JP-8 components. The blood data was used to estimate an apparent permeability coefficient ( K p). The rank order of the apparent K p was naphthalene > 1-methyl naphthalene = 2-methyl naphthalene > decane > dodecane > undecane. This rank order is similar to results from rat and pig-skin studies. However, this study demonstrates that rat and pig models of the skin over predict the internal dose of JP-8 components in humans.

Dermal Exposure to Jet Fuel JP-8 Significantly Contributes to the Production of Urinary Naphthols in Fuel-Cell Maintenance Workers

Jet propulsion fuel 8 (JP-8) is the major jet fuel used worldwide and has been recognized as a major source of chemical exposure, both inhalation and dermal, for fuel-cell maintenance workers. We investigated the contributions of dermal and inhalation exposure to JP-8 to the total body dose of U.S. Air Force fuel-cell maintenance workers using naphthalene as a surrogate for JP-8 exposure. Dermal, breathing zone, and exhaled breath measurements of naphthalene were obtained using tape-strip sampling, passive monitoring, and glass bulbs, respectively. Levels of urinary 1- and 2-naphthols were determined in urine samples and used as biomarkers of JP-8 exposure. Multiple linear regression analyses were conducted to investigate the relative contributions of dermal and inhalation exposure to JP-8, and demographic and work-related covariates, to the levels of urinary naphthols. Our results show that both inhalation exposure and smoking significantly contributed to urinary 1-naphthol levels. The contribution of dermal exposure was significantly associated with levels of urinary 2-naphthol but not with urinary 1-naphthol among fuel-cell maintenance workers who wore supplied-air respirators. We conclude that dermal exposure to JP-8 significantly contributes to the systemic dose and affects the levels of urinary naphthalene metabolites. Future work on dermal xenobiotic metabolism and toxicokinetic studies are warranted in order to gain additional knowledge on naphthalene metabolism in the skin and the contribution to systemic exposure.

Dermal Exposure to Jet Fuel (JP-8) in US Air Force Personnel

Limited research has been conducted on dermal exposure and risk assessment, owing to the lack of reliable measurement techniques and data for quantitative risk assessment. We investigated the magnitude of dermal exposure to jet propulsion fuel 8 (JP-8), using naphthalene as a surrogate, on the US Air Force fuel-cell maintenance workers. Dermal exposure of 124 workers routinely working with JP-8 was measured using a non-invasive tape-strip technique coupled with gas chromatography-mass spectrometry analysis. The contribution of job-related factors to dermal exposure was determined using multiple linear regression analyses. Average whole body dermal exposure to naphthalene (as a marker for JP-8) was 7.61 +/- 2.27 ln(ng m(-2)). Significant difference (P < 0.0001) between the high-exposure group [8.34 +/- 2.23 ln(ng m(-2))] and medium- and low-exposure groups [6.18 +/- 1.35 ln(ng m(-2)) and 5.84 +/- 1.34 ln(ng m(-2)), respectively] was observed reflecting the actual exposure scenarios. Skin irritation, use of booties, working inside the fuel tank and the duration of JP-8 exposure were significant factors explaining the whole body dermal exposure. This study clearly demonstrates the efficiency and suitability of the tape-strip technique for the assessment of dermal exposure to JP-8 and that naphthalene can serve as a useful marker of exposure and uptake of JP-8 and its components. It also showed that the skin provides a significant route for JP-8 exposure and that actions to reduce exposure are required. Studies to investigate the relative contribution of dermal uptake of JP-8 on total body dose and the toxicokinetics of dermal exposure to JP-8 are underway.