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Mundt KA, Santamaria AB, Thompson WJ, Bates CA, Boles C, Dotson GS, Yong M. Carcinogenicity of Poorly Soluble Low Toxicity Particles: Commentary on Epidemiology as a Risk Assessment “Reality Check”. Front Public Health 2022; 10:920032. [PMID: 35903380 PMCID: PMC9315308 DOI: 10.3389/fpubh.2022.920032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Accepted: 06/20/2022] [Indexed: 11/13/2022] Open
Abstract
Inhaled particles that are poorly soluble or insoluble and of low toxicity (“poorly soluble low toxicity” or “PSLT” particles), can accumulate in the lung and at lung overload levels induce lung cancers in rats. The question of whether PSLT particles increase lung cancer risk in humans is complicated by large differences between rats and humans and the relatively large particle doses administered in animal studies even when compared with heavy human occupational exposures. We review the findings of epidemiological studies on occupational exposure to each of three different PSLT particles (carbon black, talc and taconite). The epidemiological evidence indicates that at even very high occupational exposure levels at which non-malignant respiratory diseases including pneumoconiosis and even talcosis are observed, lung cancer risks appear not to be elevated. Although positive human cancer risks might be predicted based on extrapolation from overload doses in rats to relevant exposures in humans, the epidemiological “reality check” based on the three examples indicates that these PSLT particles are unlikely to increase lung cancer risk in humans even at high occupational levels of exposure. Therefore, we propose that careful evaluation of the epidemiological evidence can serve as a “reality check” for human risk assessment and help balance the risk evaluation process.
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Affiliation(s)
- Kenneth A. Mundt
- Cardno ChemRisk now Stantec, San Francisco, CA, United States
- *Correspondence: Kenneth A. Mundt
| | | | | | | | - Corey Boles
- Cardno ChemRisk now Stantec, San Francisco, CA, United States
| | - G. Scott Dotson
- Cardno ChemRisk now Stantec, San Francisco, CA, United States
| | - Mei Yong
- MY EpiConsulting, Düsseldorf, Germany
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2
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Delmaar C, Meesters J. Modeling consumer exposure to spray products: an evaluation of the ConsExpo Web and ConsExpo nano models with experimental data. JOURNAL OF EXPOSURE SCIENCE & ENVIRONMENTAL EPIDEMIOLOGY 2020; 30:878-887. [PMID: 32555302 DOI: 10.1038/s41370-020-0239-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2020] [Revised: 05/14/2020] [Accepted: 06/03/2020] [Indexed: 06/11/2023]
Abstract
To ensure safe use of chemical substances in consumer products, the exposure of consumers to these substances needs to be evaluated. For this purpose, generally consumer exposure modeling tools are used. To build confidence in such tools, evaluation of their performance with experimental data is indispensable. This work describes the evaluation of two consumer exposure modeling tools: ConsExpo Web and ConsExpo nano. Both models contain a module to estimate exposure of substances released as an aerosol during the use of spray products. This particular model was tested by comparing measured exposure data with model simulations. Experimental data were obtained from the public literature. These typically provide measured air concentrations under simulated use conditions of spray products. ConsExpo Web and ConsExpo nano were used to simulate experimental settings of the different studies. The resulting simulated air concentrations were compared with the reported ones. Overall, good agreement between modeled and measured data was observed. However, a significant proportion of the studies considered, did not provide sufficient detail in the specification of the experimental conditions to make them suitable for model evaluation. Critical information that was often lacking was on product composition, the mass sprayed during usage, and the generated aerosol size distribution.
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Affiliation(s)
- Christiaan Delmaar
- National Institute of Public Health and the Environment (RIVM) PB 1, 3720 BA, Bilthoven, The Netherlands.
| | - Joris Meesters
- National Institute of Public Health and the Environment (RIVM) PB 1, 3720 BA, Bilthoven, The Netherlands
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Bevan RJ, Kreiling R, Levy LS, Warheit DB. Toxicity testing of poorly soluble particles, lung overload and lung cancer. Regul Toxicol Pharmacol 2018; 100:80-91. [DOI: 10.1016/j.yrtph.2018.10.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Revised: 10/17/2018] [Accepted: 10/20/2018] [Indexed: 01/17/2023]
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Dobrovolskaia MA, Shurin MR, Kagan VE, Shvedova AA. Ins and Outs in Environmental and Occupational Safety Studies of Asthma and Engineered Nanomaterials. ACS NANO 2017; 11:7565-7571. [PMID: 28737932 PMCID: PMC6481664 DOI: 10.1021/acsnano.7b04916] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
According to the Centers for Disease Control and Prevention, approximately 25 million Americans suffer from asthma. The disease total annual cost is about $56 billion and includes both the direct and indirect costs of medications, hospital stays, missed work, and decreased productivity. Air pollution with xenobiotics, bacterial agents, and industrial nanomaterials, such as carbon nanotubes, contribute to the exacerbation of this condition and are a point of particular attention in environmental toxicology as well as in occupational health and safety research. Mast cell degranulation and activation of Th2 cells triggered either by allergen-specific immunoglobulin E (IgE) or by alternative mechanisms, such as locally produced neurotransmitters, underlie the pathophysiological process of airway constriction during an asthma attack. Other immune and non-immune cell types, including basophils, eosinophils, Th1, Th17, Th9, macrophages, dendritic cells, and smooth muscle cells, are involved in the inflammatory and allergic responses during asthma, which, under chronic conditions, may progress without mast cells, the key trigger of the acute asthma attack. To decipher complex molecular, cellular, and genetic mechanisms, many researchers have attempted to develop in vitro and in vivo models to study asthma. Herein, we summarize the advantages and disadvantages of various models and their applicability to nanoparticle evaluation in asthma research. We further suggest that a framework for both in vitro and in vivo methods should be used to study the impact of engineered nanomaterials on asthma etiology, pathophysiology, and treatment.
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Affiliation(s)
- Marina A. Dobrovolskaia
- Nanotechnology Characterization Laboratory, Cancer Research Technology Program, Leidos Biomedical Research Inc., Frederick National Laboratory for Cancer Research, NCI at Frederick, Frederick, MD 21702, USA
| | - Michael R. Shurin
- Department of Pathology, University of Pittsburgh Medical Center, Pittsburgh, PA 15213, USA
- Department of Immunology, University of Pittsburgh Medical Center, Pittsburgh, PA 15213, USA
| | - Valerian E. Kagan
- Departments of Environmental and Occupational Health, Pharmacology and Chemical Biology, Chemistry and Radiation Oncology and Center for Free and Antioxidant Health, University of Pittsburgh
| | - Anna A. Shvedova
- Health Effects Laboratory Division, National Institute of Occupational Safety and Health, Centers for Disease Control and Prevention, Morgantown, WV 26505, USA
- Department of Physiology and Pharmacology, West Virginia University, Morgantown, WV 26506, USA
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Warheit DB, Kreiling R, Levy LS. Relevance of the rat lung tumor response to particle overload for human risk assessment-Update and interpretation of new data since ILSI 2000. Toxicology 2016; 374:42-59. [PMID: 27876671 DOI: 10.1016/j.tox.2016.11.013] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Revised: 11/16/2016] [Accepted: 11/17/2016] [Indexed: 11/18/2022]
Abstract
The relevance of particle-overload related lung tumors in rats for human risk assessment following chronic inhalation exposures to poorly soluble particulates (PSP) has been a controversial issue for more than three decades. In 1998, an ILSI (International Life Sciences) Working Group of health scientists was convened to address this issue of applicability of experimental study findings of lung neoplasms in rats for lifetime-exposed production workers to PSPs. A full consensus view was not reached by the Workshop participants, although it was generally acknowledged that the findings of lung tumors in rats following chronic inhalation, particle-overload PSP exposures occurred only in rats and no other tested species; and that there was an absence of lung cancers in PSP-exposed production workers. Since the publication of the ILSI Workshop report in 2000, there have been important new data published on the human relevance issue. A thorough and comprehensive review of the health effects literature on poorly soluble particles/lung overload was undertaken and published by an ECETOC (European Centre for Ecotoxicology and Toxicology of Chemicals) Task Force in 2013. One of the significant conclusions derived from that technical report was that the rat is unique amongst all species in developing lung tumors under chronic inhalation overload exposures to PSPs. Accordingly, the objective of this review is to provide important insights on the fundamental differences in pulmonary responses between experimentally-exposed rats, other experimental species and occupationally-exposed humans. Briefly, five central factors are described by the following issues. Focusing on these five interrelated/convergent factors clearly demonstrate an inappropriateness in concluding that the findings of lung tumors in rats exposed chronically to high concentrations of PSPs are accurate representations of the risks of lung cancer in PSP-exposed production workers. The most plausible conclusion that can be reached is that results from chronic particle-overload inhalation studies with PSPs in rats have no relevance for determining lung cancer risks in production workers exposed for a working lifetime to these poorly soluble particulate-types.
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Affiliation(s)
| | - R Kreiling
- Clariant Produkte (DE) GmbH, Sulzbach, Germany
| | - L S Levy
- Cranfield University, Cranfield, UK
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6
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Fröhlich E, Mercuri A, Wu S, Salar-Behzadi S. Measurements of Deposition, Lung Surface Area and Lung Fluid for Simulation of Inhaled Compounds. Front Pharmacol 2016; 7:181. [PMID: 27445817 PMCID: PMC4919356 DOI: 10.3389/fphar.2016.00181] [Citation(s) in RCA: 124] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2016] [Accepted: 06/09/2016] [Indexed: 11/20/2022] Open
Abstract
Modern strategies in drug development employ in silico techniques in the design of compounds as well as estimations of pharmacokinetics, pharmacodynamics and toxicity parameters. The quality of the results depends on software algorithm, data library and input data. Compared to simulations of absorption, distribution, metabolism, excretion, and toxicity of oral drug compounds, relatively few studies report predictions of pharmacokinetics and pharmacodynamics of inhaled substances. For calculation of the drug concentration at the absorption site, the pulmonary epithelium, physiological parameters such as lung surface and distribution volume (lung lining fluid) have to be known. These parameters can only be determined by invasive techniques and by postmortem studies. Very different values have been reported in the literature. This review addresses the state of software programs for simulation of orally inhaled substances and focuses on problems in the determination of particle deposition, lung surface and of lung lining fluid. The different surface areas for deposition and for drug absorption are difficult to include directly into the simulations. As drug levels are influenced by multiple parameters the role of single parameters in the simulations cannot be identified easily.
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Affiliation(s)
- Eleonore Fröhlich
- Center for Medical Research, Medical University of GrazGraz, Austria
| | | | - Shengqian Wu
- Research Center Pharmaceutical Engineering GmbHGraz, Austria
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Leprince B, Fritsch P, Bérard P, Roméo PH. Design and functionalities of the MADOR® software suite for dose-reduction management after DTPA therapy. RADIATION PROTECTION DOSIMETRY 2016; 168:350-357. [PMID: 25999333 DOI: 10.1093/rpd/ncv348] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Accepted: 04/24/2015] [Indexed: 06/04/2023]
Abstract
A software suite on biokinetics of radionuclides and internal dosimetry intended for the occupational health practitioners of nuclear industry and for expert opinions has been developed under Borland C++ Builder™. These computing tools allow physicians to improve the dosimetric follow-up of workers in agreement with the French regulations and to manage new internal contaminations by radionuclides such as Pu and/or Am after diethylene triamine penta-acetic acid treatments. In this paper, the concept and functionalities of the first two computing tools of this MADOR(®) suite are described. The release 0.0 is the forensic application, which allows calculating the derived recording levels for intake by inhalation or ingestion of the main radioisotopes encountered in occupational environment. Indeed, these reference values of activity are convenient to interpret rapidly the bioassay measurements and make decisions as part of medical monitoring. The release 1.0 addresses the effect of DTPA treatments on Pu/Am biokinetics and the dose benefit. The forensic results of the MADOR(®) suite were validated by comparison with reference data.
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Affiliation(s)
- B Leprince
- CEA/DSV/iRCM 18 route du Panorama, BP 6, F-92265 Fontenay-aux-Roses, France
| | - P Fritsch
- CEA/DSV/iRCM 18 route du Panorama, BP 6, F-92265 Fontenay-aux-Roses, France
| | - P Bérard
- CEA/DSV/PROSITON 18 route du Panorama, BP 6, F-92265 Fontenay-aux-Roses, France
| | - P-H Roméo
- CEA/DSV/iRCM 18 route du Panorama, BP 6, F-92265 Fontenay-aux-Roses, France
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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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Kuempel ED, Sweeney LM, Morris JB, Jarabek AM. Advances in Inhalation Dosimetry Models and Methods for Occupational Risk Assessment and Exposure Limit Derivation. JOURNAL OF OCCUPATIONAL AND ENVIRONMENTAL HYGIENE 2015; 12 Suppl 1:S18-40. [PMID: 26551218 PMCID: PMC4685615 DOI: 10.1080/15459624.2015.1060328] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The purpose of this article is to provide an overview and practical guide to occupational health professionals concerning the derivation and use of dose estimates in risk assessment for development of occupational exposure limits (OELs) for inhaled substances. Dosimetry is the study and practice of measuring or estimating the internal dose of a substance in individuals or a population. Dosimetry thus provides an essential link to understanding the relationship between an external exposure and a biological response. Use of dosimetry principles and tools can improve the accuracy of risk assessment, and reduce the uncertainty, by providing reliable estimates of the internal dose at the target tissue. This is accomplished through specific measurement data or predictive models, when available, or the use of basic dosimetry principles for broad classes of materials. Accurate dose estimation is essential not only for dose-response assessment, but also for interspecies extrapolation and for risk characterization at given exposures. Inhalation dosimetry is the focus of this paper since it is a major route of exposure in the workplace. Practical examples of dose estimation and OEL derivation are provided for inhaled gases and particulates.
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Affiliation(s)
- Eileen D. Kuempel
- National Institute for Occupational Safety and Health, Education and Information Division, Cincinnati, Ohio
| | - Lisa M. Sweeney
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Naval Medical Research Unit Dayton, Wright-Patterson Air Force Base, Ohio
| | - John B. Morris
- School of Pharmacy, University of Connecticut, Storrs, Connecticut
| | - Annie M. Jarabek
- U.S. Environmental Protection Agency, National Center for Environmental Assessment, Research Triangle Park, North Carolina
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10
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Kuempel ED, Attfield MD, Stayner LT, Castranova V. Human and animal evidence supports lower occupational exposure limits for poorly-soluble respirable particles: Letter to the Editor re: 'Low-toxicity dusts: Current exposure guidelines are not sufficiently protective' by Cherrie, Brosseau, Hay and Donaldson. ACTA ACUST UNITED AC 2014; 58:1205-8. [PMID: 25193937 DOI: 10.1093/annhyg/meu058] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
- Eileen D Kuempel
- 1.National Institute for Occupational Safety and Health, Education and Information Division, 1090 Tusculum Avenue, Cincinnati, OH, USA;
| | - Michael D Attfield
- 2.National Institute for Occupational Safety and Health, Division of Respiratory Disease Studies, Morgantown, WV, USA
| | - Leslie T Stayner
- 3.University of Illinois at Chicago, School of Public Health, Division of Epidemiology and Biostatistics, Chicago, IL, USA
| | - Vincent Castranova
- 4.National Institute for Occupational Safety and Health, Health Effects Laboratory Division, Morgantown, WV, USA; 5.Department of Basic Pharmaceutical Sciences, School of Pharmacy, West Virginia University, Morgantown, WV, USA
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Application of Markov chain Monte Carlo analysis to biomathematical modeling of respirable dust in US and UK coal miners. Regul Toxicol Pharmacol 2013; 66:47-58. [PMID: 23454101 DOI: 10.1016/j.yrtph.2013.02.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2012] [Revised: 02/08/2013] [Accepted: 02/12/2013] [Indexed: 11/24/2022]
Abstract
A biomathematical model was previously developed to describe the long-term clearance and retention of particles in the lungs of coal miners. The model structure was evaluated and parameters were estimated in two data sets, one from the United States and one from the United Kingdom. The three-compartment model structure consists of deposition of inhaled particles in the alveolar region, competing processes of either clearance from the alveolar region or translocation to the lung interstitial region, and very slow, irreversible sequestration of interstitialized material in the lung-associated lymph nodes. Point estimates of model parameter values were estimated separately for the two data sets. In the current effort, Bayesian population analysis using Markov chain Monte Carlo simulation was used to recalibrate the model while improving assessments of parameter variability and uncertainty. When model parameters were calibrated simultaneously to the two data sets, agreement between the derived parameters for the two groups was very good, and the central tendency values were similar to those derived from the deterministic approach. These findings are relevant to the proposed update of the ICRP human respiratory tract model with revisions to the alveolar-interstitial region based on this long-term particle clearance and retention model.
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