1
|
Simon K, Schneider L, Oberender G, Pirow R, Hutzler C, Luch A, Roloff A. Migration of polycyclic aromatic hydrocarbons from a polymer surrogate through the stratum corneum layer of the skin. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2023; 262:115113. [PMID: 37315362 DOI: 10.1016/j.ecoenv.2023.115113] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Revised: 06/02/2023] [Accepted: 06/04/2023] [Indexed: 06/16/2023]
Abstract
In this study, we determined partition (Ksc/m) and diffusion (Dsc) coefficients of five different polycyclic aromatic hydrocarbons (PAH) migrating from squalane into and through the stratum corneum (s.c.) layer of the skin. Carcinogenic PAH have previously been detected in numerous polymer-based consumer products, especially those dyed with carbon black. Upon dermal contact with these products, PAH may penetrate into and through the viable layers of the skin by passing the s.c. and thus may become bioavailable. Squalane, a frequent ingredient in cosmetics, has also been used as a polymer surrogate matrix in previous studies. Ksc/m and Dsc are relevant parameters for risk assessment because they allow estimating the potential of a substance to become bioavailable upon dermal exposure. We developed an analytical method involving incubation of pigskin with naphthalene, anthracene, pyrene, benzo[a]pyrene and dibenzo[a,h]pyrene in Franz diffusion cell assays under quasi-infinite dose conditions. PAH were subsequently quantified within individual s.c. layers by gas chromatography coupled to tandem mass spectrometry. The resulting PAH depth profiles in the s.c. were fitted to a solution of Fick's second law of diffusion, yielding Ksc/m and Dsc. The decadic logarithm logKsc/m ranged from -0.43 to +0.69 and showed a trend to higher values for PAH with higher molecular masses. Dsc, on the other hand, was similar for the four higher molecular mass PAH but about 4.6-fold lower than for naphthalene. Moreover, our data suggests that the s.c./viable epidermis boundary layer represents the most relevant barrier for the skin penetration of higher molecular mass PAH. Finally, we empirically derived a mathematical description of the concentration depth profiles that better fits our data. We correlated the resulting parameters to substance specific constants such as the logarithmic octanol-water partition coefficient logP, Ksc/m and the removal rate at the s.c./viable epidermis boundary layer.
Collapse
Affiliation(s)
- Konstantin Simon
- German Federal Institute for Risk Assessment (BfR), Department of Chemical and Product Safety, Max-Dohrn-Str. 8-10, 10589 Berlin, Germany; Department of Biology, Chemistry, Pharmacy, Institute of Pharmacy, Freie Universität Berlin, Königin-Luise-Str. 2-4, 14195 Berlin, Germany.
| | - Lidia Schneider
- German Federal Institute for Risk Assessment (BfR), Department of Chemical and Product Safety, Max-Dohrn-Str. 8-10, 10589 Berlin, Germany
| | - Gila Oberender
- German Federal Institute for Risk Assessment (BfR), Department of Chemical and Product Safety, Max-Dohrn-Str. 8-10, 10589 Berlin, Germany; Berliner Hochschule für Technik (BHT), Luxemburger Str. 10, 13353 Berlin, Germany
| | - Ralph Pirow
- German Federal Institute for Risk Assessment (BfR), Department of Chemical and Product Safety, Max-Dohrn-Str. 8-10, 10589 Berlin, Germany
| | - Christoph Hutzler
- German Federal Institute for Risk Assessment (BfR), Department of Chemical and Product Safety, Max-Dohrn-Str. 8-10, 10589 Berlin, Germany
| | - Andreas Luch
- German Federal Institute for Risk Assessment (BfR), Department of Chemical and Product Safety, Max-Dohrn-Str. 8-10, 10589 Berlin, Germany; Department of Biology, Chemistry, Pharmacy, Institute of Pharmacy, Freie Universität Berlin, Königin-Luise-Str. 2-4, 14195 Berlin, Germany
| | - Alexander Roloff
- German Federal Institute for Risk Assessment (BfR), Department of Chemical and Product Safety, Max-Dohrn-Str. 8-10, 10589 Berlin, Germany.
| |
Collapse
|
2
|
Kapraun DF, Schlosser PM, Nylander-French LA, Kim D, Yost EE, Druwe IL. A Physiologically Based Pharmacokinetic Model for Naphthalene With Inhalation and Skin Routes of Exposure. Toxicol Sci 2021; 177:377-391. [PMID: 32687177 DOI: 10.1093/toxsci/kfaa117] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Naphthalene, a volatile organic compound present in moth repellants and petroleum-based fuels, has been shown to induce toxicity in mice and rats during chronic inhalation exposures. Although simpler default methods exist for extrapolating toxicity points of departure from animals to humans, using a physiologically based pharmacokinetic (PBPK) model to perform such extrapolations is generally preferred. Confidence in PBPK models increases when they have been validated using both animal and human in vivo pharmacokinetic (PK) data. A published inhalation PBPK model for naphthalene was previously shown to predict rodent PK data well, so we sought to evaluate this model using human PK data. The most reliable human data available come from a controlled skin exposure study, but the inhalation PBPK model does not include a skin exposure route; therefore, we extended the model by incorporating compartments representing the stratum corneum and the viable epidermis and parameters that determine absorption and rate of transport through the skin. The human data revealed measurable blood concentrations of naphthalene present in the subjects prior to skin exposure, so we also introduced a continuous dose-rate parameter to account for these baseline blood concentration levels. We calibrated the three new parameters in the modified PBPK model using data from the controlled skin exposure study but did not modify values for any other parameters. Model predictions then fell within a factor of 2 of most (96%) of the human PK observations, demonstrating that this model can accurately predict internal doses of naphthalene and is thus a viable tool for use in human health risk assessment.
Collapse
Affiliation(s)
- Dustin F Kapraun
- Center for Public Health and Environmental Assessment, Office of Research and Development, US Environmental Protection Agency, Durham, North Carolina 27711
| | - Paul M Schlosser
- Center for Public Health and Environmental Assessment, Office of Research and Development, US Environmental Protection Agency, Durham, North Carolina 27711
| | - Leena A Nylander-French
- Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - David Kim
- Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Erin E Yost
- Center for Public Health and Environmental Assessment, Office of Research and Development, US Environmental Protection Agency, Durham, North Carolina 27711
| | - Ingrid L Druwe
- Center for Public Health and Environmental Assessment, Office of Research and Development, US Environmental Protection Agency, Durham, North Carolina 27711
| |
Collapse
|
3
|
Yost EE, Galizia A, Kapraun DF, Persad AS, Vulimiri SV, Angrish M, Lee JS, Druwe IL. Health Effects of Naphthalene Exposure: A Systematic Evidence Map and Analysis of Potential Considerations for Dose-Response Evaluation. ENVIRONMENTAL HEALTH PERSPECTIVES 2021; 129:76002. [PMID: 34251878 PMCID: PMC8274693 DOI: 10.1289/ehp7381] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Revised: 05/24/2021] [Accepted: 05/26/2021] [Indexed: 05/19/2023]
Abstract
BACKGROUND Naphthalene is a polycyclic aromatic hydrocarbon that has been associated with health effects, including cancer. As the state of the science on naphthalene toxicity continues to evolve, updated toxicity reference value(s) may be required to support human health risk assessment. OBJECTIVES We present a systematic evidence map of studies that could be used to derive toxicity reference value(s) for naphthalene. METHODS Human and animal health effect studies and physiologically based pharmacokinetic (PBPK) models were identified from a literature search based on populations, exposures, comparators, and outcomes (PECO) criteria. Human and animal studies meeting PECO criteria were refined to a smaller subset considered most informative for deriving chronic reference value(s), which are preferred for assessing risk to the general public. This subset was evaluated for risk of bias and sensitivity, and the suitability of each study for dose-response analysis was qualitatively assessed. Lowest observed adverse effect levels (LOAELs) were extracted and summarized. Other potentially relevant studies (e.g., mechanistic and toxicokinetic studies) were tracked as supplemental information but not evaluated further. Existing reference values for naphthalene are also summarized. RESULTS We identified 26 epidemiology studies and 16 animal studies that were considered most informative for further analysis. Eleven PBPK models were identified. The available epidemiology studies generally had significant risk of bias and/or sensitivity concerns and were mostly found to have low suitability for dose-response analysis due to the nature of the exposure measurements. The animal studies had fewer risk of bias and sensitivity concerns and were mostly found to be suitable for dose-response analysis. CONCLUSION Although both epidemiological and animal studies of naphthalene provide weight of evidence for hazard identification, the available animal studies appear more suitable for reference value derivation. PBPK models and mechanistic and toxicokinetic data can be applied to extrapolate these animal data to humans, considering mode of action and interspecies metabolic differences. https://doi.org/10.1289/EHP7381.
Collapse
Affiliation(s)
- Erin E. Yost
- Center for Public Health and Environmental Assessment, U.S. Environmental Protection Agency, Washington, District of Columbia, USA
| | - Audrey Galizia
- Center for Public Health and Environmental Assessment, U.S. Environmental Protection Agency, Washington, District of Columbia, USA
| | - Dustin F. Kapraun
- Center for Public Health and Environmental Assessment, U.S. Environmental Protection Agency, Washington, District of Columbia, USA
| | - Amanda S. Persad
- Center for Public Health and Environmental Assessment, U.S. Environmental Protection Agency, Washington, District of Columbia, USA
| | - Suryanarayana V. Vulimiri
- Center for Public Health and Environmental Assessment, U.S. Environmental Protection Agency, Washington, District of Columbia, USA
| | - Michelle Angrish
- Center for Public Health and Environmental Assessment, U.S. Environmental Protection Agency, Washington, District of Columbia, USA
| | - Janice S. Lee
- Center for Public Health and Environmental Assessment, U.S. Environmental Protection Agency, Washington, District of Columbia, USA
| | - Ingrid L. Druwe
- Center for Public Health and Environmental Assessment, U.S. Environmental Protection Agency, Washington, District of Columbia, USA
| |
Collapse
|
4
|
RIFM fragrance ingredient safety assessment, dodecane, CAS Registry Number 112-40-3. Food Chem Toxicol 2020; 146 Suppl 1:111759. [PMID: 32966876 DOI: 10.1016/j.fct.2020.111759] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Revised: 08/27/2020] [Accepted: 09/14/2020] [Indexed: 11/20/2022]
Abstract
Dodecane was evaluated for genotoxicity, repeated dose toxicity, reproductive toxicity, local respiratory toxicity, phototoxicity/photoallergenicity, skin sensitization, and environmental safety. Data from read-across analog nonane (CAS # 111-84-2) show that dodecane is not expected to be genotoxic. Data on read-across analog undecane (CAS # 1120-21-4) provide a calculated Margin of Exposure (MOE) >100 for the repeated dose toxicity and reproductive toxicity endpoints. The skin sensitization endpoint was completed using the Dermal Sensitization Threshold (DST) for non-reactive materials (900 μg/cm2); exposure is below the DST. The phototoxicity/photoallergenicity endpoints were evaluated based on ultraviolet/visible (UV/vis) spectra; dodecane is not expected to be phototoxic/photoallergenic. The local respiratory toxicity endpoint was evaluated using the Threshold of Toxicological Concern (TTC) for a Cramer Class I material, and the exposure to dodecane is below the TTC (1.4 mg/day). The environmental endpoints were evaluated; dodecane was found not to be Persistent, Bioaccumulative, and Toxic (PBT) as per the International Fragrance Association (IFRA) Environmental Standards, and its risk quotients, based on its current volume of use in Europe and North America (i.e., Predicted Environmental Concentration/Predicted No Effect Concentration [PEC/PNEC]), are <1.
Collapse
|
5
|
Api AM, Belsito D, Biserta S, Botelho D, Bruze M, Burton GA, Buschmann J, Cancellieri MA, Dagli ML, Date M, Dekant W, Deodhar C, Fryer AD, Gadhia S, Jones L, Joshi K, Lapczynski A, Lavelle M, Liebler DC, Na M, O'Brien D, Patel A, Penning TM, Ritacco G, Rodriguez-Ropero F, Romine J, Sadekar N, Salvito D, Schultz TW, Siddiqi F, Sipes IG, Sullivan G, Thakkar Y, Tokura Y, Tsang S. RIFM fragrance ingredient safety assessment, undecane, CAS Registry Number 1120-21-4. Food Chem Toxicol 2020; 146 Suppl 1:111745. [PMID: 32937169 DOI: 10.1016/j.fct.2020.111745] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Revised: 08/10/2020] [Accepted: 09/04/2020] [Indexed: 11/24/2022]
Affiliation(s)
- A M Api
- Research Institute for Fragrance Materials, Inc., 50 Tice Boulevard, Woodcliff Lake, NJ, 07677, USA
| | - D Belsito
- Member Expert Panel, Columbia University Medical Center, Department of Dermatology, 161 Fort Washington Ave., New York, NY, 10032, USA
| | - S Biserta
- Research Institute for Fragrance Materials, Inc., 50 Tice Boulevard, Woodcliff Lake, NJ, 07677, USA
| | - D Botelho
- Research Institute for Fragrance Materials, Inc., 50 Tice Boulevard, Woodcliff Lake, NJ, 07677, USA
| | - M Bruze
- Member Expert Panel, Malmo University Hospital, Department of Occupational & Environmental Dermatology, Sodra Forstadsgatan 101, Entrance 47, Malmo, SE, 20502, Sweden
| | - G A Burton
- Member Expert Panel, School of Natural Resources & Environment, University of Michigan, Dana Building G110, 440 Church St., Ann Arbor, MI, 58109, USA
| | - J Buschmann
- Member Expert Panel, Fraunhofer Institute for Toxicology and Experimental Medicine, Nikolai-Fuchs-Strasse 1, 30625, Hannover, Germany
| | - M A Cancellieri
- Research Institute for Fragrance Materials, Inc., 50 Tice Boulevard, Woodcliff Lake, NJ, 07677, USA
| | - M L Dagli
- Member Expert Panel, University of Sao Paulo, School of Veterinary Medicine and Animal Science, Department of Pathology, Av. Prof. dr. Orlando Marques de Paiva, 87, Sao Paulo, CEP 05508-900, Brazil
| | - M Date
- Research Institute for Fragrance Materials, Inc., 50 Tice Boulevard, Woodcliff Lake, NJ, 07677, USA
| | - W Dekant
- Member Expert Panel, University of Wuerzburg, Department of Toxicology, Versbacher Str. 9, 97078, Würzburg, Germany
| | - C Deodhar
- Research Institute for Fragrance Materials, Inc., 50 Tice Boulevard, Woodcliff Lake, NJ, 07677, USA
| | - A D Fryer
- Member Expert Panel, Oregon Health Science University, 3181 SW Sam Jackson Park Rd., Portland, OR, 97239, USA
| | - S Gadhia
- Research Institute for Fragrance Materials, Inc., 50 Tice Boulevard, Woodcliff Lake, NJ, 07677, USA
| | - L Jones
- Research Institute for Fragrance Materials, Inc., 50 Tice Boulevard, Woodcliff Lake, NJ, 07677, USA
| | - K Joshi
- Research Institute for Fragrance Materials, Inc., 50 Tice Boulevard, Woodcliff Lake, NJ, 07677, USA
| | - A Lapczynski
- Research Institute for Fragrance Materials, Inc., 50 Tice Boulevard, Woodcliff Lake, NJ, 07677, USA
| | - M Lavelle
- Research Institute for Fragrance Materials, Inc., 50 Tice Boulevard, Woodcliff Lake, NJ, 07677, USA
| | - D C Liebler
- Member Expert Panel, Vanderbilt University School of Medicine, Department of Biochemistry, Center in Molecular Toxicology, 638 Robinson Research Building, 2200 Pierce Avenue, Nashville, TN, 37232-0146, USA
| | - M Na
- Research Institute for Fragrance Materials, Inc., 50 Tice Boulevard, Woodcliff Lake, NJ, 07677, USA
| | - D O'Brien
- Research Institute for Fragrance Materials, Inc., 50 Tice Boulevard, Woodcliff Lake, NJ, 07677, USA
| | - A Patel
- Research Institute for Fragrance Materials, Inc., 50 Tice Boulevard, Woodcliff Lake, NJ, 07677, USA
| | - T M Penning
- Member of Expert Panel, University of Pennsylvania, Perelman School of Medicine, Center of Excellence in Environmental Toxicology, 1316 Biomedical Research Building (BRB) II/III, 421 Curie Boulevard, Philadelphia, PA, 19104-3083, USA
| | - G Ritacco
- Research Institute for Fragrance Materials, Inc., 50 Tice Boulevard, Woodcliff Lake, NJ, 07677, USA
| | - F Rodriguez-Ropero
- Research Institute for Fragrance Materials, Inc., 50 Tice Boulevard, Woodcliff Lake, NJ, 07677, USA
| | - J Romine
- Research Institute for Fragrance Materials, Inc., 50 Tice Boulevard, Woodcliff Lake, NJ, 07677, USA
| | - N Sadekar
- Research Institute for Fragrance Materials, Inc., 50 Tice Boulevard, Woodcliff Lake, NJ, 07677, USA
| | - D Salvito
- Research Institute for Fragrance Materials, Inc., 50 Tice Boulevard, Woodcliff Lake, NJ, 07677, USA
| | - T W Schultz
- Member Expert Panel, The University of Tennessee, College of Veterinary Medicine, Department of Comparative Medicine, 2407 River Dr., Knoxville, TN, 37996- 4500, USA
| | - F Siddiqi
- Research Institute for Fragrance Materials, Inc., 50 Tice Boulevard, Woodcliff Lake, NJ, 07677, USA
| | - I G Sipes
- Member Expert Panel, Department of Pharmacology, University of Arizona, College of Medicine, 1501 North Campbell Avenue, P.O. Box 245050, Tucson, AZ, 85724-5050, USA
| | - G Sullivan
- Research Institute for Fragrance Materials, Inc., 50 Tice Boulevard, Woodcliff Lake, NJ, 07677, USA.
| | - Y Thakkar
- Research Institute for Fragrance Materials, Inc., 50 Tice Boulevard, Woodcliff Lake, NJ, 07677, USA
| | - Y Tokura
- Member Expert Panel, The Journal of Dermatological Science (JDS), Department of Dermatology, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu, 431-3192, Japan
| | - S Tsang
- Research Institute for Fragrance Materials, Inc., 50 Tice Boulevard, Woodcliff Lake, NJ, 07677, USA
| |
Collapse
|
6
|
Pinto ÉSM, Dorn M, Feltes BC. The tale of a versatile enzyme: Alpha-amylase evolution, structure, and potential biotechnological applications for the bioremediation of n-alkanes. CHEMOSPHERE 2020; 250:126202. [PMID: 32092569 DOI: 10.1016/j.chemosphere.2020.126202] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Revised: 01/10/2020] [Accepted: 02/12/2020] [Indexed: 06/10/2023]
Abstract
As the primary source of a wide range of industrial products, the study of petroleum-derived compounds is of pivotal importance. However, the process of oil extraction and refinement is among the most environmentally hazardous practices, impacting almost all levels of the ecological chain. So far, the most appropriate strategy to overcome such an issue is through bioremediation, which revolves around the employment of different microorganisms to degrade hazardous compounds, generating less environmental impact and lower monetary costs. In this sense, a myriad of organisms and enzymes are considered possible candidates for the bioremediation process. Amidst the potential candidates is α-amylase, an evolutionary conserved starch-degrading enzyme. Notably, α-amylase was not only seen to degrade n-alkanes, a subclass of alkanes considered the most abundant petroleum-derived compounds but also low-density polyethylene, a dangerous pollutant produced from petroleum. Thus, due to its high conservation in both eukaryotic and prokaryotic lineages, in addition to the capability to degrade different types of hazardous compounds, the study of α-amylase becomes a rising interest. Nevertheless, there are no studies that review all biotechnological applications of α-amylase for bioremediation. In this work, we critically review the potential biotechnological applications of α-amylase, focusing on the biodegradation of petroleum-derived compounds. Evolutionary aspects are discussed, as well for all structural information and all features that could impact on the employment of this protein in the biotechnological industry, such as pH, temperature, and medium conditions. New perspectives and critical assessments are conducted regarding the application of α-amylase in the bioremediation of n-alkanes.
Collapse
Affiliation(s)
- Éderson Sales Moreira Pinto
- Laboratory of Structural Bioinformatics and Computational Biology, Center for Biotechnology, Federal University of Rio Grande do Sul, Brazil
| | - Márcio Dorn
- Laboratory of Structural Bioinformatics and Computational Biology, Institute of Informatics, Federal University of Rio Grande do Sul, Brazil; Laboratory of Structural Bioinformatics and Computational Biology, Center for Biotechnology, Federal University of Rio Grande do Sul, Brazil
| | - Bruno César Feltes
- Laboratory of Structural Bioinformatics and Computational Biology, Institute of Informatics, Federal University of Rio Grande do Sul, Brazil.
| |
Collapse
|
7
|
Santos PM, del Nogal Sánchez M, Pavón JLP, Cordero BM. Determination of polycyclic aromatic hydrocarbons in human biological samples: A critical review. Trends Analyt Chem 2019. [DOI: 10.1016/j.trac.2019.02.010] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
|
8
|
Geer Wallace MA, Pleil JD, Oliver KD, Whitaker DA, Mentese S, Fent KW, Horn GP. Non-targeted GC/MS analysis of exhaled breath samples: Exploring human biomarkers of exogenous exposure and endogenous response from professional firefighting activity. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2019; 82:244-260. [PMID: 30907277 PMCID: PMC8668041 DOI: 10.1080/15287394.2019.1587901] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
A non-targeted analysis workflow was applied to analyze exhaled breath samples collected from firefighters pre- and post-structural fire suppression. Breath samples from firefighters functioning in attack and search positions were examined for target and non-target compounds in automated thermal desorption-GC/MS (ATD-GC/MS) selected ion monitoring (SIM)/scan mode and reviewed for prominent chemicals. Targeted chemicals included products of combustion such as benzene, toluene, xylenes, and polycyclic aromatic hydrocarbons (PAH) that serve as a standard assessment of exposure. Sixty unique chemical features representative of exogenous chemicals and endogenous compounds, including single-ring aromatics, polynuclear aromatic hydrocarbons, volatile sulfur-containing compounds, aldehydes, alkanes, and alkenes were identified using the non-targeted analysis workflow. Fifty-seven out of 60 non-targeted features changed by at least 50% from pre- to post-fire suppression activity in at least one subject, and 7 non-targeted features were found to exhibit significantly increased or decreased concentrations for all subjects as a group. This study is important for (1) alerting the firefighter community to potential new exposures, (2) expanding the current targeted list of toxicants, and (3) finding biomarkers of response to firefighting activity as reflected by changes in endogenous compounds. Data demonstrate that there are non-targeted compounds in firefighters' breath that are indicative of environmental exposure despite the use of protective gear, and this information may be further utilized to improve the effectiveness of personal protective equipment.
Collapse
Affiliation(s)
- M Ariel Geer Wallace
- a Office of Research and Development, National Exposure Research Laboratory , U.S. Environmental Protection Agency , Research Triangle Park , NC , USA
| | - Joachim D Pleil
- a Office of Research and Development, National Exposure Research Laboratory , U.S. Environmental Protection Agency , Research Triangle Park , NC , USA
| | - Karen D Oliver
- a Office of Research and Development, National Exposure Research Laboratory , U.S. Environmental Protection Agency , Research Triangle Park , NC , USA
| | - Donald A Whitaker
- a Office of Research and Development, National Exposure Research Laboratory , U.S. Environmental Protection Agency , Research Triangle Park , NC , USA
| | - Sibel Mentese
- b Department of Environmental Engineering , Çanakkale Onsekiz Mart University , Merkez/Çanakkale , Turkey
| | - Kenneth W Fent
- c Division of Surveillance, Hazard Evaluations and Field Studies , National Institute for Occupational Safety and Health (NIOSH) , Cincinnati , OH , USA
| | - Gavin P Horn
- d Illinois Fire Service Institute , University of Illinois at Urbana-Champaign , Champaign , IL , USA
| |
Collapse
|
9
|
Fife TD, Robb MJA, Steenerson KK, Saha KC. Bilateral Vestibular Dysfunction Associated With Chronic Exposure to Military Jet Propellant Type-Eight Jet Fuel. Front Neurol 2018; 9:351. [PMID: 29867750 PMCID: PMC5964212 DOI: 10.3389/fneur.2018.00351] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Accepted: 05/01/2018] [Indexed: 12/19/2022] Open
Abstract
We describe three patients diagnosed with bilateral vestibular dysfunction associated with the jet propellant type-eight (JP-8) fuel exposure. Chronic exposure to aromatic and aliphatic hydrocarbons, which are the main constituents of JP-8 military aircraft jet fuel, occurred over 3–5 years’ duration while working on or near the flight line. Exposure to toxic hydrocarbons was substantiated by the presence of JP-8 metabolite n-hexane in the blood of one of the cases. The presenting symptoms were dizziness, headache, fatigue, and imbalance. Rotational chair testing confirmed bilateral vestibular dysfunction in all the three patients. Vestibular function improved over time once the exposure was removed. Bilateral vestibular dysfunction has been associated with hydrocarbon exposure in humans, but only recently has emphasis been placed specifically on the detrimental effects of JP-8 jet fuel and its numerous hydrocarbon constituents. Data are limited on the mechanism of JP-8-induced vestibular dysfunction or ototoxicity. Early recognition of JP-8 toxicity risk, cessation of exposure, and customized vestibular therapy offer the best chance for improved balance. Bilateral vestibular impairment is under-recognized in those chronically exposed to all forms of jet fuel.
Collapse
Affiliation(s)
- Terry D Fife
- Barrow Neurological Institute, Phoenix, AZ, United States
| | | | | | - Kamala C Saha
- Barrow Neurological Institute, Phoenix, AZ, United States
| |
Collapse
|
10
|
Hopf NB, Spring P, Hirt-Burri N, Jimenez S, Sutter B, Vernez D, Berthet A. Polycyclic aromatic hydrocarbons (PAHs) skin permeation rates change with simultaneous exposures to solar ultraviolet radiation (UV-S). Toxicol Lett 2018; 287:122-130. [DOI: 10.1016/j.toxlet.2018.01.024] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Revised: 01/26/2018] [Accepted: 01/30/2018] [Indexed: 12/28/2022]
|
11
|
McKee RH, Tibaldi R, Adenuga MD, Carrillo JC, Margary A. Assessment of the potential human health risks from exposure to complex substances in accordance with REACH requirements. "White spirit" as a case study. Regul Toxicol Pharmacol 2017; 92:439-457. [PMID: 29069582 DOI: 10.1016/j.yrtph.2017.10.015] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Revised: 09/26/2017] [Accepted: 10/18/2017] [Indexed: 11/30/2022]
Abstract
The European chemical control regulation (REACH) requires that data on physical/chemical, toxicological and environmental hazards be compiled. Additionally, REACH requires formal assessments to ensure that substances can be safely used for their intended purposes. For health hazard assessments, reference values (Derived No Effect levels, DNELs) are calculated from toxicology data and compared to estimated exposure levels. If the ratio of the predicted exposure level to the DNEL, i.e. the Risk Characterization Ratio (RCR), is less than 1, the risk is considered controlled; otherwise, additional Risk Management Measures (RMM) must be applied. These requirements pose particular challenges for complex substances. Herein, "white spirit", a complex hydrocarbon solvent, is used as an example to illustrate how these procedures were applied. Hydrocarbon solvents were divided into categories of similar substances. Representative substances were identified for DNEL determinations. Adjustment factors were applied to the no effect levels to calculate the DNELs. Exposure assessments utilized a standardized set of generic exposure scenarios (GES) which incorporated exposure predictions for solvent handling activities. Computer-based tools were developed to automate RCR calculations and identify appropriate RMMs, allowing consistent communications to users via safety data sheets.
Collapse
Affiliation(s)
- Richard H McKee
- ExxonMobil Biomedical Sciences, Inc., 1545 US Highway 22 East, Annandale, NJ 08801, USA
| | - Rosalie Tibaldi
- ExxonMobil Biomedical Sciences, Inc., 1545 US Highway 22 East, Annandale, NJ 08801, USA.
| | - Moyinoluwa D Adenuga
- ExxonMobil Biomedical Sciences, Inc., 1545 US Highway 22 East, Annandale, NJ 08801, USA
| | | | - Alison Margary
- Shell Health, Shell International B.V., The Hague, The Netherlands
| |
Collapse
|
12
|
Volatile Organic Compounds in Blood as Biomarkers of Exposure to JP-8 Jet Fuel Among US Air Force Personnel. J Occup Environ Med 2016; 58:24-9. [PMID: 26716845 DOI: 10.1097/jom.0000000000000611] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE 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. METHODS 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. RESULTS 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. CONCLUSIONS These findings support the use of blood VOCs as a biomarker of occupational JP-8 exposure.
Collapse
|
13
|
Dermal uptake of petroleum substances. Toxicol Lett 2015; 235:123-39. [DOI: 10.1016/j.toxlet.2015.03.012] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2014] [Revised: 03/24/2015] [Accepted: 03/27/2015] [Indexed: 11/23/2022]
|
14
|
A strategy for in-silico prediction of skin absorption in man. Eur J Pharm Biopharm 2015; 95:68-76. [PMID: 26022643 DOI: 10.1016/j.ejpb.2015.05.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Revised: 03/09/2015] [Accepted: 05/06/2015] [Indexed: 11/21/2022]
Abstract
For some time, in-silico models to address substance transport into and through the skin are gaining more and more importance in different fields of science and industry. In particular, the mathematical prediction of in-vivo skin absorption is of great interest to overcome ethical and economical issues. The presented work outlines a strategy to address this problem and in particular, investigates in-vitro and in-vivo skin penetration experiments of the model compound flufenamic acid solved in an ointment by means of a mathematical model. Experimental stratum corneum concentration-depth profiles (SC-CDP) for various time intervals using two different in-vitro systems (Franz diffusion cell, Saarbruecken penetration model) were examined and simulated with the help of a highly optimized three compartment numerical diffusion model and compared to the findings of SC-CDPs of the in-vivo scenario. Fitted model input parameters (diffusion coefficient and partition coefficient with respect to the stratum corneum) for the in-vitro infinite dose case could be used to predict the in-use conditions in-vitro. Despite apparent differences in calculated partition coefficients between in-vivo and in-vitro studies, prediction of in-vivo scenarios from input parameters calculated from the in-vitro case yielded reasonable results.
Collapse
|
15
|
Mckee RH, Adenuga MD, Carrillo JC. Characterization of the toxicological hazards of hydrocarbon solvents. Crit Rev Toxicol 2015; 45:273-365. [DOI: 10.3109/10408444.2015.1016216] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
|
16
|
Bogen KT, Sheehan PJ. Dermal versus total uptake of benzene from mineral spirits solvent during parts washing. RISK ANALYSIS : AN OFFICIAL PUBLICATION OF THE SOCIETY FOR RISK ANALYSIS 2014; 34:1336-1358. [PMID: 24495022 DOI: 10.1111/risa.12166] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Quantitative approaches to assessing exposure to, and associated risk from, benzene in mineral spirits solvent (MSS), used widely in parts washing and degreasing operations, have focused primarily on the respiratory pathway. The dermal contribution to total benzene uptake from such operations remains uncertain because measuring in vivo experimental dermal uptake of this volatile human carcinogen is difficult. Unprotected dermal uptake involves simultaneous sustained immersion events and transient splash/wipe events, each yielding residues subject to evaporation as well as dermal uptake. A two-process dermal exposure framework to assess dermal uptake to normal and damaged skin was applied to estimate potential daily dermal benzene dose (Dskin ) to workers who used historical or current formulations of recycled MSS in manual parts washers. Measures of evaporation and absorption of MSS dermally applied to human subjects were modeled to estimate in vivo dermal uptake of benzene in MSS. Uncertainty and interindividual variability in Dskin was characterized by Monte Carlo simulation, conditioned on uncertainty and/or variability estimated for each model input. Dermal exposures are estimated to average 33% of total (inhalation + dermal) benzene parts washing dose, with approximately equal predicted portions of dermal dose due to splash/wipe and to continuous contact with MSS. The estimated median (95th percentile) dermal and total daily benzene doses from parts washing are: 0.0069 (0.024) and 0.025 (0.18) mg/day using current, and 0.027 (0.085) and 0.098 (0.69) mg/day using historical, MSS solvents, respectively.
Collapse
|
17
|
Schliemann S, Schmidt C, Elsner P. Tandem Repeated Application of Organic Solvents and Sodium Lauryl Sulphate Enhances Cumulative Skin Irritation. Skin Pharmacol Physiol 2014; 27:158-63. [DOI: 10.1159/000353919] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2013] [Accepted: 06/19/2013] [Indexed: 11/19/2022]
|
18
|
Selzer D, Abdel-Mottaleb MMA, Hahn T, Schaefer UF, Neumann D. Finite and infinite dosing: difficulties in measurements, evaluations and predictions. Adv Drug Deliv Rev 2013; 65:278-94. [PMID: 22750806 DOI: 10.1016/j.addr.2012.06.010] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2011] [Revised: 05/12/2012] [Accepted: 06/20/2012] [Indexed: 11/18/2022]
Abstract
Due to the increased demand for reliable data regarding penetration into and permeation across human skin, assessment of the absorption of xenobiotics has been gaining in importance steadily. In vitro experiments allow for determining these data faster and more easily than in vivo experiments. However, the experiments described in literature and the subsequent evaluation procedures differ considerably. Here we will give an overview on typical finite and infinite dose experiments performed in fundamental research and on the evaluation of the data. We will point out possible difficulties that may arise and give a short overview on attempts at predicting skin absorption in vitro and in vivo.
Collapse
Affiliation(s)
- Dominik Selzer
- Biopharmaceutics and Pharmaceutical Technology, Saarland University, Saarbruecken, Germany
| | | | | | | | | |
Collapse
|
19
|
Krieg EF, Mathias PI, Toennis CA, Clark JC, Marlow KL, B’Hymer C, Singh NP, Gibson RL, Butler MA. Detection of DNA damage in workers exposed to JP-8 jet fuel. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2012; 747:218-27. [DOI: 10.1016/j.mrgentox.2012.05.005] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2012] [Revised: 05/11/2012] [Accepted: 05/12/2012] [Indexed: 11/26/2022]
|
20
|
Thomasen JM, Nylander-French LA. Penetration patterns of monomeric and polymeric 1,6-hexamethylene diisocyanate monomer in human skin. ACTA ACUST UNITED AC 2012; 14:951-60. [PMID: 22293954 DOI: 10.1039/c2em10546b] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We investigated penetration patterns of monomeric and polymeric 1,6-hexamethylene diisocyanate (HDI), experimentally and as part of commercial products, in excised full-thickness human skin at 5, 10, 30, or 60 min after exposure. We observed that both monomeric and polymeric HDI were readily absorbed into the skin and that the clearcoat composition affects the penetration rate of the individual isocyanates. The short-term absorption rates for HDI monomer, biuret, and isocyanurate were determined and used to estimate the exposure time required to reach a body burden equal to the American Conference of Governmental Industrial Hygienists (ACGIH) inhalation threshold limit value (TLV) or Oregon State occupational exposure limit (OEL). Oregon is the only government entity in the United States to promulgate a short-term exposure limit (STEL) for HDI-based polyisocyanates biuret and isocyanurate. Based on these absorption rates for a slow-drying clearcoat after 10 min (1.33 μg cm(-2) h(-1)) or 60 min (0.219 μg cm(-2) h(-1)), we calculated that 6.5 and 40 min dermal exposure, respectively, is required to achieve a dose of HDI equivalent to the ACGIH TLV. For biuret, the time to achieve a dose equivalent to the Oregon OEL for slow-drying clearcoat was much shorter (<31 min) than that for fast-drying clearcoat (618 min). Isocyanurate had the shortest skin absorption times regardless of clearcoat formulation (14 s-1.7 min). These results indicate that the dose received through dermal exposure to HDI-containing clearcoats has a significant potential to exceed the dose equivalent to that received through inhalation exposure at established regulatory limits. A critical need exists to monitor dermal exposure quantitatively in exposed workers, to use proper protective equipment to reduce dermal exposure, and to re-evaluate regulatory exposure limits for isocyanates.
Collapse
Affiliation(s)
- Jennifer M Thomasen
- Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, The University of North Carolina at Chapel Hill, CB #7431, Rosenau Hall, Chapel Hill, NC, USA
| | | |
Collapse
|
21
|
Smith KW, Proctor SP, Ozonoff AL, McClean MD. Urinary biomarkers of occupational jet fuel exposure among Air Force personnel. JOURNAL OF EXPOSURE SCIENCE & ENVIRONMENTAL EPIDEMIOLOGY 2012; 22:35-45. [PMID: 22044926 DOI: 10.1038/jes.2011.38] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2010] [Accepted: 04/15/2011] [Indexed: 05/31/2023]
Abstract
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.
Collapse
Affiliation(s)
- Kristen W Smith
- Department of Environmental Health, Harvard University School of Public Health, Boston, Massachusetts, USA.
| | | | | | | |
Collapse
|
22
|
Kang-Sickel JCC, Butler MA, Frame L, Serdar B, Chao YCE, Egeghy P, Rappaport SM, Toennis CA, Li W, Borisova T, French JE, Nylander-French LA. The utility of naphthyl-keratin adducts as biomarkers for jet-fuel exposure. Biomarkers 2011; 16:590-9. [PMID: 21961652 DOI: 10.3109/1354750x.2011.611598] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
We investigated the association between biomarkers of dermal exposure, naphthyl-keratin adducts (NKA), and urine naphthalene biomarker levels in 105 workers routinely exposed to jet-fuel. A moderate correlation was observed between NKA and urine naphthalene levels (p = 0.061). The NKA, post-exposure breath naphthalene, and male gender were associated with an increase, while CYP2E1*6 DD and GSTT1-plus (++/+-) genotypes were associated with a decrease in urine naphthalene level (p < 0.0001). The NKA show great promise as biomarkers for dermal exposure to naphthalene. Further studies are warranted to characterize the relationship between NKA, other exposure biomarkers, and/or biomarkers of biological effects due to naphthalene and/or PAH exposure.
Collapse
Affiliation(s)
- Juei-Chuan C Kang-Sickel
- Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, The University of North Carolina at Chapel Hill, USA
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
23
|
(2-Methoxyethoxy)acetic acid: a urinary biomarker of exposure for jet fuel JP-8. Int Arch Occup Environ Health 2011; 85:413-20. [DOI: 10.1007/s00420-011-0687-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2011] [Accepted: 07/19/2011] [Indexed: 10/17/2022]
|
24
|
Schliemann S, Antonov D, Manegold N, Elsner P. Sensory irritation caused by two organic solvents-short-time single application and repeated occlusive test in stingers and non-stingers. Contact Dermatitis 2011; 65:107-14. [DOI: 10.1111/j.1600-0536.2011.01938.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
25
|
Schliemann S, Antonov D, Manegold N, Elsner P. The lactic acid stinging test predicts susceptibility to cumulative irritation caused by two lipophilic irritants*. Contact Dermatitis 2010; 63:347-56. [DOI: 10.1111/j.1600-0536.2010.01777.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
|
26
|
Smith KW, Proctor SP, Ozonoff A, McClean MD. Inhalation exposure to jet fuel (JP8) among U.S. Air Force personnel. JOURNAL OF OCCUPATIONAL AND ENVIRONMENTAL HYGIENE 2010; 7:563-572. [PMID: 20694886 DOI: 10.1080/15459624.2010.503755] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
As jet fuel is a common occupational exposure among military and civilian populations, this study was conducted to characterize jet fuel (JP8) exposure among active duty U.S. Air Force personnel. Personnel (n = 24) were divided a priori into high, moderate, and low exposure groups. Questionnaires and personal air samples (breathing zone) were collected from each worker over 3 consecutive days (72 worker-days) and analyzed for total hydrocarbons (THC), benzene, toluene, ethylbenzene, xylenes, and naphthalene. Air samples were collected from inside the fuel tank and analyzed for the same analytes. Linear mixed-effects models were used to evaluate the exposure data. Our results show that the correlation of THC (a measure of overall JP8 inhalation exposure) with all other analytes was moderate to strong in the a priori high and moderate exposure groups combined. Inhalation exposure to all analytes varied significantly by self-reported JP8 exposure (THC levels higher among workers reporting JP8 exposure), a priori exposure group (THC levels in high group > moderate group > low group), and more specific job task groupings (THC levels among workers in fuel systems hangar group > refueling maintenance group > fuel systems office group > fuel handling group > clinic group), with task groupings explaining the most between-worker variability. Among highly exposed workers, statistically significant job task-related predictors of inhalation exposure to THC indicated that increased time in the hangar, working close to the fuel tank (inside > less than 25 ft > greater than 25 ft), primary job (entrant > attendant/runner/fireguard > outside hangar), and performing various tasks near the fuel tank, such as searching for a leak, resulted in higher JP8 exposure. This study shows that while a priori exposure groups were useful in distinguishing JP8 exposure levels, job task-based categories should be considered in epidemiologic study designs to improve exposure classification. Finally, the strong correlation of THC with naphthalene suggests that naphthalene may be an appropriate surrogate of JP8 exposure. [Supplementary materials are available for this article. Go to the publisher's online edition of the Journal of Occupational and Environmental Hygiene for the following free supplemental resource: a pdf file containing a table detailing concentrations of JP8 components.].
Collapse
Affiliation(s)
- Kristen W Smith
- Department of Environmental Health, Boston University School of Public Health, Boston, Massachusetts 02115, USA.
| | | | | | | |
Collapse
|
27
|
Kang-Sickel JCC, Stober VP, French JE, Nylander-French LA. Exposure to naphthalene induces naphthyl-keratin adducts in human epidermis in vitro and in vivo. Biomarkers 2010; 15:488-97. [PMID: 20500019 PMCID: PMC2923669 DOI: 10.3109/1354750x.2010.485700] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
We observed naphthyl-keratin adducts and dose-related metabolic enzyme induction at the mRNA level in reconstructed human epidermis in vitro after exposure to naphthalene. Immunofluorescence detection of 2-naphthyl-keratin-1 adducts confirmed the metabolism of naphthalene and adduction of keratin. We also observed naphthyl-keratin adducts in dermal tape-strip samples collected from naphthalene-exposed workers at levels ranging from 0.004 to 6.104 pmol adduct microg(-1) keratin. We have demonstrated the ability of the human skin to metabolize naphthalene and to form naphthyl-keratin adducts both in vitro and in vivo. The results indicate the potential use of keratin adducts as biomarkers of dermal exposure.
Collapse
Affiliation(s)
- Juei-chuan C. Kang-Sickel
- Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Vandy P. Stober
- Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - John E. French
- Host Susceptibility Branch, National Toxicology Program, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina, USA
| | - Leena A. Nylander-French
- Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| |
Collapse
|
28
|
Pleil JD, Stiegel MA, Sobus JR, Tabucchi S, Ghio AJ, Madden MC. Cumulative exposure assessment for trace-level polycyclic aromatic hydrocarbons (PAHs) using human blood and plasma analysis. J Chromatogr B Analyt Technol Biomed Life Sci 2010; 878:1753-60. [PMID: 20488767 DOI: 10.1016/j.jchromb.2010.04.035] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2010] [Revised: 03/31/2010] [Accepted: 04/24/2010] [Indexed: 12/26/2022]
Abstract
Humans experience chronic cumulative trace-level exposure to mixtures of volatile, semi-volatile, and non-volatile polycyclic aromatic hydrocarbons (PAHs) present in the environment as by-products of combustion processes. Certain PAHs are known or suspected human carcinogens and so we have developed methodology for measuring their circulating (blood borne) concentrations as a tool to assess internal dose and health risk. We use liquid/liquid extraction and gas chromatography-mass spectrometry and present analytical parameters including dynamic range (0-250 ng/ml), linearity (>0.99 for all compounds), and instrument sensitivity (range 2-22 pg/ml) for a series of 22 PAHs representing 2-6-rings. The method is shown to be sufficiently sensitive for estimating PAHs baseline levels (typical median range from 1 to 1000 pg/ml) in groups of normal control subjects using 1-ml aliquots of human plasma but we note that some individuals have very low background concentrations for 5- and 6-ring compounds that fall below robust quantitation levels.
Collapse
Affiliation(s)
- J D Pleil
- Human Exposure and Atmospheric Sciences Division, NERL/ORD, U.S. Environmental Protection Agency, Research Triangle Park, NC, USA.
| | | | | | | | | | | |
Collapse
|
29
|
ten Berge W. A simple dermal absorption model: derivation and application. CHEMOSPHERE 2009; 75:1440-1445. [PMID: 19304310 DOI: 10.1016/j.chemosphere.2009.02.043] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2008] [Revised: 02/11/2009] [Accepted: 02/17/2009] [Indexed: 05/27/2023]
Abstract
This paper deals with the derivation of a QSAR for the estimation of: the skin permeation coefficient from aqueous solutions in cm h(-1), the stratum corneum/water partition coefficient. These QSARs enable the estimation of: the aqueous permeation coefficient in cm h(-1), the maximum dermal absorption in mg cm(-2) h(-1) from a saturated aqueous solution at steady state, the lag time in hours (h), the diffusivity of a substance in the stratum corneum in cm2 h(-1). By using the independent variables: the log(octanol/water partition coefficient), the molecular weight,the water solubility. The estimated maximum dermal absorption and the lag time were compared with some recent measured data of substances, which were not used for developing the QSARs. The estimates were generally in the same order of magnitude as the measured absorption and lag time. These QSARs are recommended for risk assessment of chemicals in the scope of the European REACH legislation.
Collapse
Affiliation(s)
- Wil ten Berge
- Santoxar, Wolter Visscherstraat 40, 6931CV Westervoort, The Netherlands.
| |
Collapse
|
30
|
Lin CY, Wheelock AM, Morin D, Baldwin RM, Lee MG, Taff A, Plopper C, Buckpitt A, Rohde A. Toxicity and metabolism of methylnaphthalenes: comparison with naphthalene and 1-nitronaphthalene. Toxicology 2009; 260:16-27. [PMID: 19464565 DOI: 10.1016/j.tox.2009.03.002] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2008] [Revised: 03/01/2009] [Accepted: 03/02/2009] [Indexed: 11/16/2022]
Abstract
Naphthalene and close structural analogues have been shown to cause necrosis of bronchiolar epithelial cells in mice by both inhalation exposure and by systemic administration. Cancer bioassays of naphthalene in mice have demonstrated a slight increase in bronchiolar/alveolar adenomas in female mice, and in inflammation and metaplasia of the olfactory epithelium in the nasal cavity. Similar work in rats demonstrated a significant, and concentration-dependent increase in the incidence of respiratory epithelial adenomas and neuroblastomas in the nasal epithelium of both male and female rats. Although the studies on the acute toxicity of the methylnaphthalene derivatives are more limited, it appears that the species selective toxicity associated with naphthalene administration also is observed with methylnaphthalenes. Chronic administration of the methylnaphthalenes, however, failed to demonstrate the same oncogenic potential as that observed with naphthalene. The information available on the isopropylnaphthalene derivatives suggests that they are not cytotoxic. Like the methylnaphthalenes, 1-nitronaphthalene causes lesions in both Clara and ciliated cells. However, the species selective lung toxicity observed in the mouse with both naphthalene and the methylnaphthalenes is not seen with 1-nitronaphthalene. With 1-nitronaphthalene, the rat is far more susceptible to parenteral administration of the compound than mice. The wide-spread distribution of these compounds in the environment and the high potential for low level exposure to humans supports a need for further work on the mechanisms of toxicity in animal models with attention to whether these processes are applicable to humans. Although it is tempting to suppose that the toxicity and mechanisms of toxicity of the alkylnaphthalenes and nitronaphthalenes are similar to naphthalene, there is sufficient published literature to suggest that this may not be the case. Certainly the enzymes involved in the metabolic activation of each of these substrates are likely to differ. The available data showing extensive oxidation of the aromatic nucleus of naphthalene, nitronaphthalene and the methylnaphthalenes (with some oxidation of the methyl group) contrast with the isopropylnaphthalene derivatives, where the major metabolites involve side chain oxidation. Overall, these data support the view that ring epoxidation is a key step in the process involved in cytotoxicity. Whether the epoxide itself or a downstream metabolite mediates the toxic effects is still not clear even with naphthalene, the best studied of this group of compounds. Additional work is needed in several areas to further assess the potential human health consequences of exposure to these agents. These studies should involve the definition of the extent and severity of methylnaphthalene toxicity after single dose exposures with attention to both the nasal and respiratory epithelia. The cytochromes P450 responsible for the initial activation of these agents in rodents with subsequent complimentary studies in primate models should help determine whether key metabolic processes responsible for toxicity occur also in primates. Finally, the precise involvement of reactive metabolite formation and adduction of cellular proteins in toxicity will be important in not only assessing the potential for human toxicity, but also in developing an understanding of the genetic and environmental factors which could alter the toxicity of these agents.
Collapse
Affiliation(s)
- Ching Yu Lin
- Department of Molecular Biosciences and Anatomy, School of Veterinary Medicine, University of California, Davis, CA 95616, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
31
|
Gatti AM, Tossini D, Gambarelli A, Montanari S, Capitani F. Investigation of the Presence of Inorganic Micro- and Nanosized Contaminants in Bread and Biscuits by Environmental Scanning Electron Microscopy. Crit Rev Food Sci Nutr 2008; 49:275-82. [DOI: 10.1080/10408390802064347] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
|
32
|
Chambers DM, Blount BC, McElprang DO, Waterhouse MG, Morrow JC. Picogram measurement of volatile n-alkanes (n-hexane through n-dodecane) in blood using solid-phase microextraction to assess nonoccupational petroleum-based fuel exposure. Anal Chem 2008; 80:4666-74. [PMID: 18481873 DOI: 10.1021/ac800065d] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We describe here a new method for the analysis of alkanes ( n-hexane, n-heptane, n-octane, n-nonane, n-decane, n-undecane, and n-dodecane) in blood using headspace solid-phase microextraction gas chromatography/mass spectrometry. This method is used to measure picogram per milliliter levels of n-alkanes in blood that may result from nonoccupational exposure to alkanes and other volatile nonpolar compounds from common sources such as petroleum-based fuel. This alkane signature is useful in distinguishing typical fuel biomarkers (e.g., benzene and toluene) from other confounding exposure sources such as cigarette smoke. Development of this method required special attention to sample handling as alkanes are not highly soluble in aqueous matrixes and exist as ubiquitous compounds found in many laboratory materials and the environment. In particular, significant n-hexane contamination ( approximately 0.4 ng/mL) occurred from collecting blood samples in vacutainers. This residue was removed by boiling the vacutainer stoppers in methanol followed by vacuum baking. For all the alkanes, the calculated accuracy demonstrated for the water-based standards ranged from 3.3% to 17% as deduced from the difference of the lowest and middle standards from the curve fit. Quality control data among runs over a 10 month period were found to vary from 14% to -29%, with a few exceptions. The resulting quantification limits for n-hexane through n-decane ranged from 0.069 to 0.132 ng/mL. In the analysis of 1200 blood samples from people with no known occupational exposure, median blood levels for all n-alkanes were below these quantification limits. n-Hexane levels above the method detection limit were, however, found in 1.3% of the samples.
Collapse
Affiliation(s)
- David M Chambers
- Division of Laboratory Sciences, National Center for Environmental Health, Centers for Disease Control and Prevention, 4770 Buford Highway, Atlanta, Georgia 30341, USA.
| | | | | | | | | |
Collapse
|
33
|
Kim D, Farthing MW, Miller CT, Nylander-French LA. Mathematical description of the uptake of hydrocarbons in jet fuel into the stratum corneum of human volunteers. Toxicol Lett 2008; 178:146-51. [DOI: 10.1016/j.toxlet.2008.03.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2008] [Revised: 03/10/2008] [Accepted: 03/10/2008] [Indexed: 11/30/2022]
|
34
|
Kang-Sickel JCC, Fox DD, Nam TG, Jayaraj K, Ball LM, French JE, Klapper DG, Gold A, Nylander-French LA. S-Arylcysteine−Keratin Adducts as Biomarkers of Human Dermal Exposure to Aromatic Hydrocarbons. Chem Res Toxicol 2008; 21:852-8. [DOI: 10.1021/tx7003773] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Juei-Chuan C. Kang-Sickel
- Department of Environmental Sciences and Engineering, School of Public Health, and Department of Microbiology and Immunology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, and Laboratory of Molecular Toxicology, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709
| | - Donii D. Fox
- Department of Environmental Sciences and Engineering, School of Public Health, and Department of Microbiology and Immunology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, and Laboratory of Molecular Toxicology, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709
| | - Tae-gyu Nam
- Department of Environmental Sciences and Engineering, School of Public Health, and Department of Microbiology and Immunology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, and Laboratory of Molecular Toxicology, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709
| | - Karupiah Jayaraj
- Department of Environmental Sciences and Engineering, School of Public Health, and Department of Microbiology and Immunology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, and Laboratory of Molecular Toxicology, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709
| | - Louise M. Ball
- Department of Environmental Sciences and Engineering, School of Public Health, and Department of Microbiology and Immunology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, and Laboratory of Molecular Toxicology, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709
| | - John E. French
- Department of Environmental Sciences and Engineering, School of Public Health, and Department of Microbiology and Immunology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, and Laboratory of Molecular Toxicology, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709
| | - David G. Klapper
- Department of Environmental Sciences and Engineering, School of Public Health, and Department of Microbiology and Immunology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, and Laboratory of Molecular Toxicology, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709
| | - Avram Gold
- Department of Environmental Sciences and Engineering, School of Public Health, and Department of Microbiology and Immunology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, and Laboratory of Molecular Toxicology, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709
| | - Leena A. Nylander-French
- Department of Environmental Sciences and Engineering, School of Public Health, and Department of Microbiology and Immunology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, and Laboratory of Molecular Toxicology, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709
| |
Collapse
|
35
|
Eriksson K, Hagström K, Axelsson S, Nylander-French L. Tape-stripping as a method for measuring dermal exposure to resin acids during wood pellet production. ACTA ACUST UNITED AC 2008; 10:345-52. [DOI: 10.1039/b719152a] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
36
|
Kim D, Andersen ME, Chao YCE, Egeghy PP, Rappaport SM, Nylander-French LA. PBTK modeling demonstrates contribution of dermal and inhalation exposure components to end-exhaled breath concentrations of naphthalene. ENVIRONMENTAL HEALTH PERSPECTIVES 2007; 115:894-901. [PMID: 17589597 PMCID: PMC1892111 DOI: 10.1289/ehp.9778] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2006] [Accepted: 02/14/2007] [Indexed: 05/10/2023]
Abstract
BACKGROUND Dermal 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. OBJECTIVE Our 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. METHODS The 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. RESULTS The optimized values of parameters for naphthalene were a) permeability coefficient for the stratum corneum 6.8 x 10(-5) cm/hr, b) permeability coefficient for the viable epidermis 3.0 x 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%). CONCLUSIONS PBTK 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.
Collapse
Affiliation(s)
- David Kim
- Department of Environmental Sciences and Engineering, School of Public Health, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Melvin E. Andersen
- CIIT Centers for Health Research, Research Triangle Park, North Carolina, USA
| | - Yi-Chun E. Chao
- Department of Environmental Sciences and Engineering, School of Public Health, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Peter P. Egeghy
- Department of Environmental Sciences and Engineering, School of Public Health, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Stephen M. Rappaport
- Department of Environmental Sciences and Engineering, School of Public Health, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Leena A. Nylander-French
- Department of Environmental Sciences and Engineering, School of Public Health, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
- Address correspondence to L.A. Nylander-French, Department of Environmental Sciences and Engineering, School of Public Health, The University of North Carolina at Chapel Hill, CB #7431, Rosenau Hall, Chapel Hill, NC 27599-7431 USA. Telephone: (919) 966-3826. Fax: (919) 966-4711. E-mail:
| |
Collapse
|
37
|
McDougal JN, Garrett CM. Gene expression and target tissue dose in the rat epidermis after brief JP-8 and JP-8 aromatic and aliphatic component exposures. Toxicol Sci 2007; 97:569-81. [PMID: 17337753 DOI: 10.1093/toxsci/kfm037] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
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.
Collapse
Affiliation(s)
- James N McDougal
- Boonshoft School of Medicine, Wright State University, Dayton, OH 45435, USA.
| | | |
Collapse
|
38
|
Kim D, Andersen ME, Nylander-French LA. A Dermatotoxicokinetic Model of Human Exposures to Jet Fuel. Toxicol Sci 2006; 93:22-33. [PMID: 16801332 DOI: 10.1093/toxsci/kfl048] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Workers, both in the military and the commercial airline industry, are exposed to jet fuel by inhalation and dermal contact. We present a dermatotoxicokinetic (DTK) model that quantifies the absorption, distribution, and elimination of aromatic and aliphatic components of jet fuel following dermal exposures in humans. Kinetic data were obtained from 10 healthy volunteers following a single dose of JP-8 to the forearm over a surface area of 20 cm2. Blood samples were taken before exposure (t = 0 h), after exposure (t = 0.5 h), and every 0.5 h for up to 3.5 h postexposure. The DTK model that best fit the data included five compartments: (1) surface, (2) stratum corneum (SC), (3) viable epidermis, (4) blood, and (5) storage. The DTK model was used to predict blood concentrations of the components of JP-8 based on dermal-exposure measurements made in occupational-exposure settings in order to better understand the toxicokinetic behavior of these compounds. Monte Carlo simulations of dermal exposure and cumulative internal dose demonstrated no overlap among the low-, medium-, and high-exposure groups. The DTK model provides a quantitative understanding of the relationship between the mass of JP-8 components in the SC and the concentrations of each component in the systemic circulation. The model may be used for the development of a toxicokinetic modeling strategy for multiroute exposure to jet fuel.
Collapse
Affiliation(s)
- David Kim
- Department of Environmental Sciences and Engineering, School of Public Health, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7431, USA
| | | | | |
Collapse
|