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Lee YS, Sung JH, Song KS, Kim JK, Choi BS, Yu IJ, Park JD. Derivation of occupational exposure limits for multi-walled carbon nanotubes and graphene using subchronic inhalation toxicity data and a multi-path particle dosimetry model. Toxicol Res (Camb) 2019; 8:580-586. [PMID: 31367339 DOI: 10.1039/c9tx00026g] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Accepted: 05/22/2019] [Indexed: 11/21/2022] Open
Abstract
In this study, we aimed to provide the recommended occupational exposure limits (OELs) for multi-walled carbon nanotubes (MWCNTs) and graphene nanomaterials based on data from a subchronic inhalation toxicity study using a lung dosimetry model. We used a no observed adverse effect level (NOAEL) of 0.98 mg m-3 and 3.02 mg m-3 in rats for MWCNTs and graphene, respectively. The NOAELs were obtained from a 13-week inhalation study in rats. The deposition fractions of MWCNTs and graphene in the respiratory tract of rats and humans were calculated by using the multi-path particle dosimetry model (MPPD model, v3.04). The deposition fraction in the alveolar region was 0.0527 and 0.0984 for MWCNTs and 0.0569 and 0.1043 for graphene in rats and human lungs, respectively. Then, the human equivalent exposure concentrations (HECs) of MWCNTs and graphene were calculated according to the method by the National Institute for Occupational Safety and Health (NIOSH). The HEC was estimated to be 0.17 mg m-3 for MWCNTs and to be 0.54 mg m-3 for graphene, which was relevant to the rat NOAEL of 0.98 mg m-3 and 3.02 mg m-3 for MWCNTs and graphene, respectively. Finally, we estimated the recommended OELs by applying uncertainty factors (UFs) to the HEC as follows: an UF of 3 for species differences (rats to humans), 2 for an experimental duration (subchronic to chronic), and 5 for inter-individual variations among workers. Thus, the OEL was estimated to be 6 μg m-3 for MWCNTs and 18 μg m-3 for graphene. These values could be useful in preventing the adverse health effects of nanoparticles in workers.
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Affiliation(s)
- Young-Sub Lee
- Department of Preventive Medicine , College of Medicine , Chung-Ang University , Seoul 06974 , Korea . ; ; Tel: +82-2-820-5668
| | | | | | - Jin-Kwon Kim
- Department of Nanofusion Technology , Hoseo University , Asan 31499 , Korea
| | - Byung-Sun Choi
- Department of Preventive Medicine , College of Medicine , Chung-Ang University , Seoul 06974 , Korea . ; ; Tel: +82-2-820-5668
| | - Il-Je Yu
- HCTm Co. , LTD , Icheon 17383 , Korea
| | - Jung-Duck Park
- Department of Preventive Medicine , College of Medicine , Chung-Ang University , Seoul 06974 , Korea . ; ; Tel: +82-2-820-5668
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Miller FJ, Conolly RB, Kimbell JS. An updated analysis of respiratory tract cells at risk for formaldehyde carcinogenesis. Inhal Toxicol 2018; 29:586-597. [DOI: 10.1080/08958378.2018.1430191] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
| | | | - Julia S. Kimbell
- Department of Otolaryngology/Head & Neck Surgery, School of Medicine, University of North Carolina, Chapel Hill, NC, USA
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Oller AR, Oberdörster G. Incorporation of dosimetry in the derivation of reference concentrations for ambient or workplace air: a conceptual approach. JOURNAL OF AEROSOL SCIENCE 2016; 99:40-45. [PMID: 27721518 PMCID: PMC5051659 DOI: 10.1016/j.jaerosci.2016.01.015] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Dosimetric models are essential tools to refine inhalation risk assessments based on local respiratory effects. Dosimetric adjustments to account for differences in aerosol particle size and respiratory tract deposition and/or clearance among rodents, workers, and the general public can be applied to experimentally- and epidemiologically-determined points of departure (PODs) to calculate size-selected (e.g., PM10, inhalable aerosol fraction, respirable aerosol fraction) equivalent concentrations (e.g., HEC or Human Equivalent Concentration; REC or Rodent Equivalent Concentration). A modified POD (e.g., HEC) can then feed into existing frameworks for the derivation of occupational or ambient air concentration limits or reference concentrations. HECs that are expressed in terms of aerosol particle sizes experienced by humans but are derived from animal studies allow proper comparison of exposure levels and associated health effects in animals and humans. This can inform differences in responsiveness between animals and humans, based on the same deposited or retained doses and can also allow the use of both data sources in an integrated weight of evidence approach for hazard and risk assessment purposes. Whenever possible, default values should be replaced by substance-specific and target population-specific parameters. Assumptions and sources of uncertainty need to be clearly reported.
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Affiliation(s)
- Adriana R Oller
- NiPERA, 2525 Meridian Parkway, Suite 240, Durham, NC 27713, USA
| | - Günter Oberdörster
- University of Rochester, Dpt. of Environmental Medicine, 575 Elmwood Ave., Medical Center Box 850, Rochester, NY 14642, USA
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Dealing with nanosafety around the globe-Regulation vs. innovation. Int J Pharm 2016; 509:95-106. [PMID: 27184102 DOI: 10.1016/j.ijpharm.2016.05.015] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Revised: 04/18/2016] [Accepted: 05/06/2016] [Indexed: 12/14/2022]
Abstract
In recent years, nanotechnology has become increasingly important for global industries. Today, many nanomaterials are used as ingredients in cosmetics, food products, medical devices and pharmaceuticals. In some cases they exert unexpected risks and potentially pose a threat to human health and the environment. Regulatory authorities all over the world carefully observe recent developments in this area, striving to find a balance between consumer safety and the interests of the industry. In the following, the current legislation in the United States of America, the European Union, Asia and Brazil will be presented. Further, the requirements defined by these different authorities and methodology to investigate relevant characteristics of nanomaterials will be discussed.
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Weldon BA, M. Faustman E, Oberdörster G, Workman T, Griffith WC, Kneuer C, Yu IJ. Occupational exposure limit for silver nanoparticles: considerations on the derivation of a general health-based value. Nanotoxicology 2016; 10:945-56. [DOI: 10.3109/17435390.2016.1148793] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
- Brittany A. Weldon
- Institute for Risk Analysis and Risk Communication, University of Washington, Seattle, WA, USA,
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA, USA,
| | - Elaine M. Faustman
- Institute for Risk Analysis and Risk Communication, University of Washington, Seattle, WA, USA,
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA, USA,
| | - Günter Oberdörster
- Department of Environmental Medicine, University of Rochester, Rochester, NY, USA,
| | - Tomomi Workman
- Institute for Risk Analysis and Risk Communication, University of Washington, Seattle, WA, USA,
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA, USA,
| | - William C. Griffith
- Institute for Risk Analysis and Risk Communication, University of Washington, Seattle, WA, USA,
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA, USA,
| | - Carsten Kneuer
- Federal Institute for Risk Assessment, Berlin, Germany, and
| | - Il Je Yu
- Institute of Nanoproduct Safety Research, Hoseo University, Asan, Korea
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Hofmann W, Winkler-Heil R. From cellular doses to average lung dose. RADIATION PROTECTION DOSIMETRY 2015; 167:49-54. [PMID: 25920789 DOI: 10.1093/rpd/ncv219] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Sensitive basal and secretory cells receive a wide range of doses in human bronchial and bronchiolar airways. Variations of cellular doses arise from the location of target cells in the bronchial epithelium of a given airway and the asymmetry and variability of airway dimensions of the lung among airways in a given airway generation and among bronchial and bronchiolar airway generations. To derive a single value for the average lung dose which can be related to epidemiologically observed lung cancer risk, appropriate weighting scenarios have to be applied. Potential biological weighting parameters are the relative frequency of target cells, the number of progenitor cells, the contribution of dose enhancement at airway bifurcations, the promotional effect of cigarette smoking and, finally, the application of appropriate regional apportionment factors. Depending on the choice of weighting parameters, detriment-weighted average lung doses can vary by a factor of up to 4 for given radon progeny exposure conditions.
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Affiliation(s)
- W Hofmann
- Department of Materials Research and Physics, University of Salzburg, Hellbrunner Str. 34, 5020 Salzburg, Austria
| | - R Winkler-Heil
- Department of Materials Research and Physics, University of Salzburg, Hellbrunner Str. 34, 5020 Salzburg, Austria
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Oller AR, Oberdörster G, Seilkop SK. Derivation of PM10 size-selected human equivalent concentrations of inhaled nickel based on cancer and non-cancer effects on the respiratory tract. Inhal Toxicol 2015; 26:559-78. [PMID: 25055843 DOI: 10.3109/08958378.2014.932034] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Abstract Nickel (Ni) in ambient air is predominantly present in the form of oxides and sulfates, with the distribution of Ni mass between the fine (particle aerodynamic diameter < 2.5 µm; PM2.5) and coarser (2.5-10 µm) size-selected aerosol fractions of PM10 dependent on the aerosol's origin. When deriving a long-term health protective reference concentration for Ni in ambient air, the respiratory toxicity and carcinogenicity effects of the predominant Ni compounds in ambient air must be considered. Dosimetric adjustments to account for differences in aerosol particle size and respiratory tract deposition and/or clearance among rats, workers, and the general public were applied to experimentally- and epidemiologically-determined points of departure (PODs) such as no(low)-effect concentrations, for both cancer and non-cancer respiratory effects. This approach resulted in the derivation of threshold-based PM10 size-selected equivalent concentrations (modified PODs) of 0.5 µg Ni/m(3) based on workers' cancer effects and 9-11 µg Ni/m(3) based on rodent respiratory toxicity effects. Sources of uncertainty in exposure extrapolations are described. These are not reference concentrations; rather the derived PM10 size-selected modified PODs can be used as the starting point for the calculation of ambient air reference concentrations for Ni. The described approach is equally applicable to other particulates.
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Oberdörster G, Castranova V, Asgharian B, Sayre P. Inhalation Exposure to Carbon Nanotubes (CNT) and Carbon Nanofibers (CNF): Methodology and Dosimetry. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART B, CRITICAL REVIEWS 2015; 18:121-212. [PMID: 26361791 PMCID: PMC4706753 DOI: 10.1080/10937404.2015.1051611] [Citation(s) in RCA: 98] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Carbon nanotubes (CNT) and nanofibers (CNF) are used increasingly in a broad array of commercial products. Given current understandings, the most significant life-cycle exposures to CNT/CNF occur from inhalation when they become airborne at different stages of their life cycle, including workplace, use, and disposal. Increasing awareness of the importance of physicochemical properties as determinants of toxicity of CNT/CNF and existing difficulties in interpreting results of mostly acute rodent inhalation studies to date necessitate a reexamination of standardized inhalation testing guidelines. The current literature on pulmonary exposure to CNT/CNF and associated effects is summarized; recommendations and conclusions are provided that address test guideline modifications for rodent inhalation studies that will improve dosimetric extrapolation modeling for hazard and risk characterization based on the analysis of exposure-dose-response relationships. Several physicochemical parameters for CNT/CNF, including shape, state of agglomeration/aggregation, surface properties, impurities, and density, influence toxicity. This requires an evaluation of the correlation between structure and pulmonary responses. Inhalation, using whole-body exposures of rodents, is recommended for acute to chronic pulmonary exposure studies. Dry powder generator methods for producing CNT/CNF aerosols are preferred, and specific instrumentation to measure mass, particle size and number distribution, and morphology in the exposure chambers are identified. Methods are discussed for establishing experimental exposure concentrations that correlate with realistic human exposures, such that unrealistically high experimental concentrations need to be identified that induce effects under mechanisms that are not relevant for workplace exposures. Recommendations for anchoring data to results seen for positive and negative benchmark materials are included, as well as periods for postexposure observation. A minimum data set of specific bronchoalveolar lavage parameters is recommended. Retained lung burden data need to be gathered such that exposure-dose-response correlations may be analyzed and potency comparisons between materials and mammalian species are obtained considering dose metric parameters for interpretation of results. Finally, a list of research needs is presented to fill data gaps for further improving design, analysis, and interpretation and extrapolation of results of rodent inhalation studies to refine meaningful risk assessments for humans.
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Affiliation(s)
- Günter Oberdörster
- Department of Environmental Medicine, University of Rochester, Rochester, New York, USA
| | - Vincent Castranova
- Formerly with the National Institute for Occupational Safety and Health, West Virginia University School of Pharmacy, Morgantown, West Virginia, USA
| | | | - Phil Sayre
- Formerly with the U.S. Environmental Protection Agency, Washington, DC, USA
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Efremenko AY, Campbell JL, Dodd DE, Oller AR, Clewell HJ. Time- and concentration-dependent genomic responses of the rat airway to inhaled nickel subsulfide. Toxicol Appl Pharmacol 2014; 279:441-454. [PMID: 24952340 DOI: 10.1016/j.taap.2014.06.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Revised: 05/27/2014] [Accepted: 06/06/2014] [Indexed: 01/16/2023]
Abstract
OBJECTIVE To provide insights into the mode of action for Ni3S2 lung carcinogenicity by examining gene expression changes in target cells after inhalation exposure. METHODS Gene expression changes were determined in micro-dissected lung broncho-alveolar cells from Fischer 344 rats following inhalation of Ni3S2 at 0.0, 0.04, 0.08, 0.15, and 0.60 mg/m(3) (0.03, 0.06, 0.11, and 0.44 mgNi/m(3)) for one and four weeks (6h/day, 5 days/week). RESULTS Broncho-alveolar lavage fluid evaluation and lung histopathology provided evidence of inflammation only at the two highest concentrations, which were similar to those tested in the 2-year bioassay. The number of statistically significant up- and down-regulated genes decreased markedly from one to four weeks of exposure, suggesting adaptation. Cell signal pathway enrichment at both time-points primarily reflected responses to toxicity, including inflammatory and proliferative signaling. While proliferative signaling was up-regulated at both time points, some inflammatory signaling reversed from down-regulation at 1 week to up-regulation at 4 weeks. CONCLUSIONS These results support a mode of action for Ni3S2 carcinogenicity driven by chronic toxicity, inflammation and proliferation, leading to mis-replication, rather than by direct genotoxicity. Benchmark dose (BMD) analysis identified the lowest pathway transcriptional BMD exposure concentration as 0.026 mgNi/m(3), for apoptosis/survival signaling. When conducted on the basis of lung Ni concentration the lowest pathway BMD was 0.64 μgNi/g lung, for immune/inflammatory signaling. IMPLICATIONS These highly conservative BMDs could be used to derive a point of departure in a nonlinear risk assessment for Ni3S2 toxicity and carcinogenicity.
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Affiliation(s)
- A Y Efremenko
- The Hamner Institutes for Health Sciences, 6 Davis Drive, Research Triangle Park, NC 27709, USA.
| | - J L Campbell
- The Hamner Institutes for Health Sciences, 6 Davis Drive, Research Triangle Park, NC 27709, USA
| | - D E Dodd
- The Hamner Institutes for Health Sciences, 6 Davis Drive, Research Triangle Park, NC 27709, USA
| | - A R Oller
- NiPERA, Inc., 2525 Meridian Parkway, Suite 240, Durham, NC 27713, USA
| | - H J Clewell
- The Hamner Institutes for Health Sciences, 6 Davis Drive, Research Triangle Park, NC 27709, USA
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Sauer UG, Vogel S, Hess A, Kolle SN, Ma-Hock L, van Ravenzwaay B, Landsiedel R. In vivo–in vitro comparison of acute respiratory tract toxicity using human 3D airway epithelial models and human A549 and murine 3T3 monolayer cell systems. Toxicol In Vitro 2013; 27:174-90. [DOI: 10.1016/j.tiv.2012.10.007] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2012] [Revised: 10/04/2012] [Accepted: 10/11/2012] [Indexed: 10/27/2022]
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