1
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Fiocchi A, Monaci L, De Angelis E, Calandrelli V, Dahdah L, Valluzzi R, Urbani S, Mazzuca C, Arasi S, Cafarotti A, Riccardi C, Artesani MC, Putignani L, Pecora V, Marzano V, Fierro V. Reactivity to allergenic food contaminants: A study on products on the market. Clin Transl Allergy 2023; 13:e12301. [PMID: 37746792 PMCID: PMC10515704 DOI: 10.1002/clt2.12301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Revised: 07/17/2023] [Accepted: 08/29/2023] [Indexed: 09/26/2023] Open
Abstract
BACKGROUND The frequency and severity of reactions in food-allergic consumers exposed to unintentional food allergen contamination during production is unknown. To warn allergic consumers, it has been suggested for pre-packaged foods to be precautionary labelled when the food allergen contamination may exceed the amount to which 1%-5% of the population could react (ED01-ED05). ED01 for hazelnut and milk have been estimated at 0.1 and 0.2 mg, respectively, by the Voluntary Incidental Trace Allergen Labelling (VITAL) initiative. The respective reference doses recommended by the FAO/WHO Codex consultation are 3 and 2 mg. We evaluated the reactivity to potential traces of milk and hazelnut allergens in allergen-free pre-packaged products by children affected by severe allergies to milk and hazelnuts. METHODS Oral Food Challenges with commercially available hazelnut-free wafer biscuits and milk-free chocolate pralines were administered to patients with severe food allergies to hazelnut and cow's milk, respectively. Contamination levels of milk or hazelnut allergens were measured using chromatographic separation interfaced with triple quadrupole mass spectrometry. RESULTS No hazelnut allergic patient showed allergic reactions to exposure to biscuits, nor any milk allergic patient displayed allergic reactions to the dark chocolate praline. While no hazelnut trace was detected in biscuits, the praline was found to be contaminated by milk at concentrations ranging between 8 and 35 mg total protein/kg food. In our dose model, these amounts exceeded 1.5-10 times the VITAL ED01 and reached the threshold suggested by the FAO/WHO Codex consultation. CONCLUSIONS Upon the consumption of food products available on the market, many patients with severe food allergies tolerate significantly higher doses of allergen than reference doses indicated in the VITAL system used for precautionary allergen labelling. These doses support the safety of the FAO/WHO recommended reference doses.
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Affiliation(s)
| | - Linda Monaci
- Institute of Sciences of Food ProductionCNR‐ISPABariItaly
| | | | | | - Lamia Dahdah
- Allergy DptBambino Gesù Children's HospitalIRCCSRomeItaly
| | - Rocco Valluzzi
- Allergy DptBambino Gesù Children's HospitalIRCCSRomeItaly
| | - Sara Urbani
- Allergy DptBambino Gesù Children's HospitalIRCCSRomeItaly
| | - Carmen Mazzuca
- Allergy DptBambino Gesù Children's HospitalIRCCSRomeItaly
| | - Stefania Arasi
- Allergy DptBambino Gesù Children's HospitalIRCCSRomeItaly
| | | | - Carla Riccardi
- Allergy DptBambino Gesù Children's HospitalIRCCSRomeItaly
| | | | - Lorenza Putignani
- Unit of Microbiology and Diagnostic ImmunologyBambino Gesù Children's HospitalIRCCSRomeItaly
- Unit of Human MicrobiomeDepartment of Diagnostics and Laboratory MedicineBambino Gesù Children's HospitalIRCCSRomeItaly
| | | | - Valeria Marzano
- Unit of Microbiology and Diagnostic ImmunologyBambino Gesù Children's HospitalIRCCSRomeItaly
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2
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Harari H, Bello D, Woskie S, Redlich CA. Assessment of personal inhalation and skin exposures to polymeric methylene diphenyl diisocyanate during polyurethane fabric coating. Toxicol Ind Health 2022; 38:622-635. [PMID: 35694796 DOI: 10.1177/07482337221107243] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Methylene diphenyl diisocyanate (MDI) monomers and polymeric MDI (pMDI) are aromatic isocyanates widely used in the production of polyurethanes. These isocyanates can cause occupational asthma, hypersensitivity pneumonitis, as well as contact dermatitis. Skin exposure likely contributes toward initial sensitization but is challenging to monitor and quantitate. In this work, we characterized workers' personal inhalation and skin exposures to pMDI in a polyurethane fabric coating factory for subsequent health effect studies. Full-shift personal and area air samples were collected from eleven workers in representative job areas daily for 1-2 weeks. Skin exposure to hands was evaluated concomitantly with a newly developed reagent-impregnated cotton glove dosimeter. Samples were analyzed for pMDI by liquid chromatography-tandem mass spectrometry. In personal airborne samples, the concentration of 4,4'-MDI isomer, expressed as total NCO, had a geometric mean (GM) and geometric standard deviation (GSD) of 5.1 and 3.3 ng NCO/m3, respectively (range: 0.5-1862 ng NCO/m3). Other MDI isomers were found at much lower concentrations. Analysis of 4,4'-MDI in the glove dosimeters exhibited much greater exposures (GM: 10 ng/cm2) and substantial variability (GSD: 20 ng NCO/cm2; range: 0-295 ng NCO/cm2). MDI inhalation exposure was well below occupational limits for MDI for all the job areas. However, MDI skin exposure to hands was substantial. These findings demonstrated the potential for substantial isocyanate skin exposure in work settings with very low airborne levels. This exposure characterization should inform future studies that aim to assess the health effects of work exposures to MDI and the effectiveness of protective measures.
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Affiliation(s)
- Homero Harari
- Department of Environmental Medicine and Public Health, 5925Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Dhimiter Bello
- Department of Biomedical and Nutritional Sciences, Zuckerberg College of Health Sciences, Lowell, MA, USA
| | - Susan Woskie
- Department of Public Health, Zuckerberg College of Health Sciences, Lowell, MA, USA
| | - Carrie A Redlich
- Yale Occupational and Environmental Medicine Program, 12228Yale School of Medicine, New Haven, CT, USA
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3
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Schupp T, Plehiers PM. Absorption, distribution, metabolism, and excretion of methylene diphenyl diisocyanate and toluene diisocyanate: Many similarities and few differences. Toxicol Ind Health 2022; 38:500-528. [PMID: 35301910 DOI: 10.1177/07482337211060133] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Methylene diphenyl diisocyanate (MDI) and toluene diisocyanate (TDI) are high production volume chemicals used for the manufacture of polyurethanes. For both substances, the most relevant adverse health effects after overexposure in the workplace are isocyanate-induced asthma, lung function decrement and, to a much lesser extent, skin effects. Over the last two decades many articles have addressed the reactivity of MDI and TDI in biological media and the associated biochemistry, which increased the understanding of their biochemical and physiological behavior. In this review, these new insights with respect to similarities and differences concerning the adsorption, distribution, metabolism, and excretion (ADME) of these two diisocyanates and the implications on their toxicities are summarized. Both TDI and MDI show very similar behavior in reactivity to biological macromolecules, distribution, metabolism, and excretion. Evidence suggests that the isocyanate (NCO) group is scavenged at the portal-of-entry and is not systemically available in unbound reactive form. This explains the lack of other than portal-of-entry toxicity observed in repeated-dose inhalation tests.
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Affiliation(s)
- Thomas Schupp
- 39002Münster University of Applied Sciences, Steinfurt, Germany
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4
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Dekant W, Colnot T. Evaluation of animal toxicity studies with diisocyanates regarding presence of thresholds for induction and elicitation of respiratory allergy by quantitative weight of evidence. Toxicol Ind Health 2022; 38:578-594. [PMID: 35148210 DOI: 10.1177/07482337211069234] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Animal toxicity studies on diisocyanates were evaluated using quantitative weight of evidence (QWoE) to test the hypothesis that the dose-response curve shows a threshold for the induction and/or elicitation of respiratory sensitization. A literature search identified 59 references that included at least two concentration groups of the diisocyanate and a vehicle-exposed concurrent control in the study design. These studies were subjected to a QWoE-assessment applying scoring criteria for quality and relevance/strength of effects relevant to the selected endpoint of respiratory sensitization. Overall, the studies assessing dose/concentration-response for diisocyanates with the endpoint, respiratory sensitization, were heterogenous regarding study design, animal models used, endpoints assessed, and quality. Only a limited number of the studies subjected to the QWoE-assessment allowed drawing conclusions about possible thresholds for respiratory sensitization. Highest quality and relevance/strength of effects scores were obtained by a series of studies specifically designed to investigate a potential threshold for elicitation of respiratory sensitization in the Brown Norway (BN) rat. These studies applied an elaborate study design to optimize induction of respiratory sensitization and reduce interference by respiratory tract irritation. In summary, the available studies provided moderate to good support for the existence of a threshold for elicitation and limited to moderate support for a threshold regarding induction of respiratory allergy by diisocyanates in experimental animals. However, a quantitative extrapolation of threshold values established in rodents to humans remains complex.
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Affiliation(s)
- Wolfgang Dekant
- Department of Toxicology, University of Würzburg, Würzburg, Germany
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5
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Pauluhn J, Whalan JE. Human risk assessment of inhaled irritants: Role of sensory stimulations from spatially separated nociceptors. Toxicology 2021; 462:152929. [PMID: 34481904 DOI: 10.1016/j.tox.2021.152929] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Revised: 08/25/2021] [Accepted: 09/01/2021] [Indexed: 12/01/2022]
Abstract
Contemporary approaches to human health risk assessment for respiratory tract irritants are variable and controversial. This manuscript provides an in-depth analysis and assessment of the applicability of the classical respiratory depression 50 % (RD50) assay with focus on the Log-linear extrapolation of the non-sensory irritant threshold (RD0 or RD10) relative to the contemporary Point of Departure (POD) U.S.-EPA benchmark approach. Three prototypic volatile chemically reactive irritants are used to exemplify the pros and cons of this alternative approach. These irritants differ in physicochemical properties affecting water-solubility and lipophilicity. Depending on these variables, a vapor may preferentially be retained in the extrathoracic region (ET), the tracheobronchial region (TB), and the pulmonary region (PU); although a smooth transition between these regions occurs at increasingly high concentrations. Each region has its specific nociceptors sensing irritants and regional-specific response to injury. The alternative approach using rats identified the chemical-specific critical region of respiratory tract injury. Statistically derived PODs on ET-TB related sensory irritation provide important information for ET-TB irritants but not for PU irritants. The POD of ET-TB irritants from acute and repeated studies decreased substantially. In summary, statistically derived PODs improve the risk assessment of respiratory tract irritants; however, those from repeated exposures should be given preference to those from acute exposures.
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Affiliation(s)
- Juergen Pauluhn
- Covestro Deutschland AG, Global Phosgene Steering Group, 51365, Leverkusen, Germany; Bayer HealthCare, Wuppertal, Germany.
| | - John E Whalan
- U.S. Environmental Protection Agency (EPA), National Center for Environmental Assessment (NCEA), 1200 Pennsylvania Avenue, N.W., Washington, D.C., 20460, USA.
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6
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PARK RM. Risk Assessment for Toluene Diisocyanate and Respiratory Disease Human Studies. Saf Health Work 2021; 12:174-183. [PMID: 34178394 PMCID: PMC8209360 DOI: 10.1016/j.shaw.2020.12.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Revised: 12/08/2020] [Accepted: 12/09/2020] [Indexed: 12/29/2022] Open
Abstract
BACKGROUND Toluene diisocyanate (TDI) is a highly reactive chemical that causes sensitization and has also been associated with increased lung cancer. A risk assessment was conducted based on occupational epidemiologic estimates for several health outcomes. METHODS Exposure and outcome details were extracted from published studies and a NIOSH Health Hazard Evaluation for new onset asthma, pulmonary function measurements, symptom prevalence, and mortality from lung cancer and respiratory disease. Summary exposure-response estimates were calculated taking into account relative precision and possible survivor selection effects. Attributable incidence of sensitization was estimated as were annual proportional losses of pulmonary function. Excess lifetime risks and benchmark doses were calculated. RESULTS Respiratory outcomes exhibited strong survivor bias. Asthma/sensitization exposure response decreased with increasing facility-average TDI air concentration as did TDI-associated pulmonary impairment. In a mortality cohort where mean employment duration was less than 1 year, survivor bias pre-empted estimation of lung cancer and respiratory disease exposure response. CONCLUSION Controlling for survivor bias and assuming a linear dose-response with facility-average TDI concentrations, excess lifetime risks exceeding one per thousand occurred at about 2 ppt TDI for sensitization and respiratory impairment. Under alternate assumptions regarding stationary and cumulative effects, one per thousand excess risks were estimated at TDI concentrations of 10 - 30 ppt. The unexplained reported excess mortality from lung cancer and other lung diseases, if attributable to TDI or associated emissions, could represent a lifetime risk comparable to that of sensitization.
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Affiliation(s)
- Robert M. PARK
- Division of Science Integration, Risk Evaluation Branch, National Institute for Occupational Safety and Health, Cincinnati, OH, USA
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7
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Zhang Y, Li F, Peng N, Peng L. Environmental impact assessment of air-permeable plastic runway production in China. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 730:139073. [PMID: 32388380 DOI: 10.1016/j.scitotenv.2020.139073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2020] [Revised: 04/25/2020] [Accepted: 04/26/2020] [Indexed: 06/11/2023]
Abstract
With the rapid development of plastic runways in China, incidents of toxic runways that are detrimental to human health frequently occurred. This phenomenon has resulted in public concern on the safety and cleanliness of plastic runways. To improve the sustainability of these runways, the environmental performance of the produced plastic runways should be evaluated. The critical hotspots for plastic runway studies should be determined, and a cleaner optimization path of critical materials should be explored. In this study, a cradle-to-gate life cycle assessment (LCA) on the air-permeable plastic runway was conducted. The green factory formula was identified, and the environmental impacts of the production process were quantitatively analyzed. Detailed life cycle inventory data were obtained from the on-site survey of typical plastic runway manufacturer enterprises in China. Environmental impacts were calculated using the CML 2001 method built into the GaBi 8.0 software. Results indicated that the 1: 7 ratio of polyurethane adhesive to ethylene-propylene-diene monomer rubber particles was the greenest formula with the least environmental impact. The environmental hotspots were from the front-end of raw material production during the mixing phase and the biomass steam input during the curing phase. The characteristic pollutants generated from mixing phase were CO2, methane, NOx, and VOCs, whereas those from the curing phase were CO2, NOx, SO2, freon, HCl, and NH3. Moreover, methylene diisocyanate (MDI) was the cleaner raw material for air-permeable plastic runway production, because the environmental impact of producing an equal mass of MDI was 39%-89% of that by toluene diisocyanate. Thus, this LCA study presents a strategy for the sustainable improvement of air-permeable plastic runway production and also proposes policy recommendations for decision makers.
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Affiliation(s)
- Yi Zhang
- College of the Environment & Ecology, Xiamen University, Xiang'an South Road, Xiang'an District, Xiamen 361102, China.
| | - Feng Li
- Taizhou Ecological Environment Bureau, Yonghui Road, Hailing District, Taizhou City, Jiangsu Province, 225300, China
| | - Najun Peng
- College of the Environment & Ecology, Xiamen University, Xiang'an South Road, Xiang'an District, Xiamen 361102, China.
| | - Lihong Peng
- College of the Environment & Ecology, Xiamen University, Xiang'an South Road, Xiang'an District, Xiamen 361102, China.
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8
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Wisnewski AV, Liu J, Redlich CA. Analysis of Lung Gene Expression Reveals a Role for Cl - Channels in Diisocyanate-induced Airway Eosinophilia in a Mouse Model of Asthma Pathology. Am J Respir Cell Mol Biol 2020; 63:25-35. [PMID: 32101465 PMCID: PMC7328250 DOI: 10.1165/rcmb.2019-0400oc] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Accepted: 02/25/2020] [Indexed: 12/23/2022] Open
Abstract
Diisocyanates are well-recognized causes of asthma. However, sensitized workers frequently lack diisocyanate-specific IgE, which complicates diagnosis and suggests the disease involves IgE-independent mechanisms. We used a mouse model of methylene diphenyl diisocyanate (MDI) asthma to identify biological pathways that may contribute to asthma pathogenesis. MDI sensitization and respiratory tract exposure were performed in Balb/c, transgenic B-cell (e.g., IgE)-deficient mice and a genetic background (C57BL/6)-matched strain. Eosinophils in airway fluid were quantitated by flow cytometry. Lung tissue gene expression was assessed using whole-genome mRNA microarrays. Informatic software was used to identify biological pathways affected by respiratory tract exposure and potential targets for disease intervention. Airway eosinophilia and changes (>1.5-fold; P value < 0.05) in expression of 192 genes occurred in all three mouse strains tested, with enrichment in chemokines and a pattern associated with alternatively activated monocytes/macrophages. CLCA1 (calcium-activated chloride channel regulator 1) was the most upregulated gene transcript (>100-fold) in all exposed mouse lungs versus controls, followed closely by SLC26A4, another transcript involved in Cl- conductance. Crofelemer, a U.S. Food and Drug Administration-approved Cl- channel inhibitor, reduced MDI exposure induction of airway eosinophilia, mucus, CLCA1, and other asthma-associated gene transcripts. Expression changes in a core set of genes occurs independent of IgE in a mouse model of chemical-induced airway eosinophilia. In addition to chemokines and alternatively activated monocytes/macrophages, the data suggest a crucial role for Cl- channels in diisocyanate asthma pathology and as a possible target for intervention.
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Affiliation(s)
- Adam V Wisnewski
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut
| | - Jian Liu
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut
| | - Carrie A Redlich
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut
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9
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Pauluhn J. Concentration × time analyses of sensory irritants revisited: Weight of evidence or the toxic load approach. That is the question. Toxicol Lett 2019; 316:94-108. [DOI: 10.1016/j.toxlet.2019.09.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Revised: 07/07/2019] [Accepted: 09/03/2019] [Indexed: 12/25/2022]
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10
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Yu G, Zhang Y, Wang X, Sai L, Bo C, Yeo AJ, Lavin MF, Peng C, Jia Q, Shao H. Thymic stromal lymphopoietin (TSLP) and Toluene-diisocyanate-induced airway inflammation: Alleviation by TSLP neutralizing antibody. Toxicol Lett 2019; 317:59-67. [PMID: 31577921 DOI: 10.1016/j.toxlet.2019.09.021] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Revised: 09/16/2019] [Accepted: 09/27/2019] [Indexed: 12/14/2022]
Abstract
Toluene-diisocyanate (TDI) is mainly used in the manufacturing process of polyurethane foams, and is a potent inducer of occupational asthma characterized by airway inflammation and airway hyperreactivity. Thymic stromal lymphopoietin (TSLP) plays an important role in the development of asthma, and correlating with the differentiation of Th2 and Th17 cells. However, the role of TSLP in TDI-induced asthma remains unclear. In this study, 96 TDI-exposed workers as well as a mouse model of TDI-induced asthma were investigated. The air exposure assessment result of TDI in the workplace showed that workers were exposed to inhalation of a very high concentration of TDI, approximately 8 times the recommended level, leading to a decrease in pulmonary function and an increase in inflammatory cells, as well as TSLP and IgE levels in the supernatant of sputum obtained from exposed workers. In order to further investigate the role of TSLP in the pathogenesis of TDI-induced asthma, a mouse model of TDI-induced asthma was also employed. Histopathological analysis of mouse lung and bronchus showed an obvious infiltration of inflammatory cells around the bronchus. The levels of inflammatory cells, IFN-γ, IL-4 and IL-17 in bronchoalveolar lavage fluid (BALF), the expression levels of TSLP protein and ROR-γt and IL-17 mRNA in mouse lung tissues were also significantly increased. However, after treatment with TSLP neutralizing antibody (TSLP-Ab), the degree of pulmonary and bronchial inflammation in mice was significantly alleviated, and the levels of inflammatory cells, IFN-γ, IL-4 and IL-17 in BALF, and the expression levels of ROR-γt and IL-17 mRNA in lung tissue were significantly decreased. Our data shows that TSLP plays an important role in the pathogenesis of TDI-induced asthma, and that TSLP-Ab can effectively alleviate TDI-induced airway inflammation of asthma.
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Affiliation(s)
- Gongchang Yu
- Shandong Academy of Occupational Health and Occupational Medicine, Shandong First Medical University & Shandong Academy of Medical Sciences, Ji'nan, Shandong, China; School of Public Health, Shandong University, Ji'nan, Shandong, China
| | - Yu Zhang
- Shandong Academy of Occupational Health and Occupational Medicine, Shandong First Medical University & Shandong Academy of Medical Sciences, Ji'nan, Shandong, China
| | - Xiaoqun Wang
- Pathology Department, New Drug Evaluation Center of Shandong Academy of Pharmaceutical Sciences, Ji'nan, Shandong, China
| | - Linlin Sai
- Shandong Academy of Occupational Health and Occupational Medicine, Shandong First Medical University & Shandong Academy of Medical Sciences, Ji'nan, Shandong, China
| | - Cunxiang Bo
- Shandong Academy of Occupational Health and Occupational Medicine, Shandong First Medical University & Shandong Academy of Medical Sciences, Ji'nan, Shandong, China
| | - Abrey J Yeo
- Shandong Academy of Occupational Health and Occupational Medicine, Shandong First Medical University & Shandong Academy of Medical Sciences, Ji'nan, Shandong, China; University of Queensland Centre for Clinical Research (UQCCR), Brisbane, Australia, Brisbane, Queensland, Australia
| | - Martin F Lavin
- Shandong Academy of Occupational Health and Occupational Medicine, Shandong First Medical University & Shandong Academy of Medical Sciences, Ji'nan, Shandong, China; University of Queensland Centre for Clinical Research (UQCCR), Brisbane, Australia, Brisbane, Queensland, Australia
| | - Cheng Peng
- Shandong Academy of Occupational Health and Occupational Medicine, Shandong First Medical University & Shandong Academy of Medical Sciences, Ji'nan, Shandong, China; The University of Queensland, Queensland Alliance for Environmental Health Sciences (QAEHS), Brisbane, Queensland, Australia
| | - Qiang Jia
- Shandong Academy of Occupational Health and Occupational Medicine, Shandong First Medical University & Shandong Academy of Medical Sciences, Ji'nan, Shandong, China.
| | - Hua Shao
- Shandong Academy of Occupational Health and Occupational Medicine, Shandong First Medical University & Shandong Academy of Medical Sciences, Ji'nan, Shandong, China.
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11
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Pollaris L, Van Den Broucke S, Decaesteker T, Cremer J, Seys S, Devos FC, Provoost S, Maes T, Verbeken E, Vande Velde G, Nemery B, Hoet PHM, Vanoirbeek JAJ. Dermal exposure determines the outcome of repeated airway exposure in a long-term chemical-induced asthma-like mouse model. Toxicology 2019; 421:84-92. [PMID: 31071364 DOI: 10.1016/j.tox.2019.05.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2019] [Revised: 04/24/2019] [Accepted: 05/05/2019] [Indexed: 12/28/2022]
Abstract
BACKGROUND Exposure to diisocyanates is an important cause of occupational asthma (OA) in the industrialized world. Since OA occurs after long-term exposure to diisocyanates, we developed a chronic mouse model of chemical-induced asthma where toluene diisocyanate (TDI) was administered at two different exposure sites. OBJECTIVES Evaluating the effect of long-term respiratory isocyanate exposure - with or without prior dermal exposure- on sensitization, inflammatory responses and airway hyperreactivity (AHR). METHODS On days 1 and 8, BALB/c mice were dermally treated (20 μl/ear) with 0.5% 2,4-toluene diisocyanate TDI or the vehicle acetone olive oil (AOO) (3:2). Starting from day 15, mice received intranasal instillations with 0.1% TDI of vehicle five times in a week, for five successive weeks. One day after the last instillation airway hyperreactivity (AHR) to methacholine was assessed, followed by an evaluation of pulmonary inflammation and structural lung changes. Immune-related parameters were assessed in the lungs (BAL and tissue), blood, cervical- and auricular lymph nodes. RESULTS Mice repeatedly intranasally exposed to TDI showed systemic sensitization and a mixed Th1/Th2 type immune response, without the presence of AHR. However, when mice are first dermally sensitized with TDI, followed by repeated intranasal TDI challenges, this results in a pronounced Th2 response and AHR. CONCLUSION Dermal exposure to TDI determines airway hyperreactivity after repeated airway exposure to TDI.
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Affiliation(s)
- Lore Pollaris
- Centre for Environment and Health, Department of Public Health and Primary Care, University of Leuven, Leuven, Belgium
| | - Sofie Van Den Broucke
- Centre for Environment and Health, Department of Public Health and Primary Care, University of Leuven, Leuven, Belgium
| | - Tatjana Decaesteker
- Laboratory of Respiratory Diseases, Department of Chronic Diseases, Metabolism and Ageing, University of Leuven, Leuven, Belgium
| | - Jonathan Cremer
- Laboratory of Clinical Immunology, Department of Microbiology and Immunology, University of Leuven, Leuven, Belgium
| | - Sven Seys
- Laboratory of Clinical Immunology, Department of Microbiology and Immunology, University of Leuven, Leuven, Belgium
| | - Fien C Devos
- Centre for Environment and Health, Department of Public Health and Primary Care, University of Leuven, Leuven, Belgium
| | - Sharen Provoost
- Laboratory for Translational Research in Obstructive Pulmonary Diseases, Department of Respiratory Medicine, Ghent University Hospital, Ghent, Belgium
| | - Tania Maes
- Laboratory for Translational Research in Obstructive Pulmonary Diseases, Department of Respiratory Medicine, Ghent University Hospital, Ghent, Belgium
| | - Erik Verbeken
- Translational Cell and Tissue Research, Department of Imaging and Pathology, University of Leuven, Leuven, Belgium
| | | | - Benoit Nemery
- Centre for Environment and Health, Department of Public Health and Primary Care, University of Leuven, Leuven, Belgium
| | - Peter H M Hoet
- Centre for Environment and Health, Department of Public Health and Primary Care, University of Leuven, Leuven, Belgium
| | - Jeroen A J Vanoirbeek
- Centre for Environment and Health, Department of Public Health and Primary Care, University of Leuven, Leuven, Belgium.
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Lynch HN, Prueitt RL, Goodman JE. Critique of the ACGIH 2016 derivation of toluene diisocyanate Threshold Limit Values. Regul Toxicol Pharmacol 2018; 97:189-196. [PMID: 29964120 DOI: 10.1016/j.yrtph.2018.06.017] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Revised: 06/26/2018] [Accepted: 06/28/2018] [Indexed: 12/11/2022]
Abstract
In 2016, the American Conference of Governmental Industrial Hygienists (ACGIH) lowered the 8-hr Threshold Limit Value - time-weighted average (TLV-TWA) for toluene diisocyanate (TDI) from 5 ppb to 1 ppb, and the 15-min short-term exposure limit (STEL) from 20 ppb to 5 ppb. We evaluated ACGIH's basis for lowering these values. It is our opinion that the ACGIH's evaluation of the evidence for occupational asthma and respiratory effects from TDI exposure does not fully integrate the results of all the available human and animal studies. We found that some studies reported occupational asthma cases at TWAs less than 5 ppb, but these cases were likely caused by peak exposures above 20 ppb. Advances in industrial hygiene have reduced peak exposures and the incidence of upset conditions, such as spills and accidents, in modern TDI facilities. Taken together, the human evidence indicates that adherence to the previous 8-hr TLV-TWA and 15-min STEL (5 ppb and 20 ppb, respectively) prevents most, if not all, cases of occupational asthma, and eliminates or reduces the risk of lung function decrements and other respiratory effects. While limited, the animal literature supports the human evidence and indicates that TDI-induced asthma is a threshold phenomenon. We conclude that ACGIH's decision to lower the TLV-TWA and STEL values for TDI is not adequately supported.
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Daniels RD. Occupational asthma risk from exposures to toluene diisocyanate: A review and risk assessment. Am J Ind Med 2018; 61:282-292. [PMID: 29389014 DOI: 10.1002/ajim.22815] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/21/2017] [Indexed: 01/23/2023]
Abstract
BACKGROUND Toluene Diisocyanate (TDI) is a known respiratory sensitizer linked to occupational asthma (OA). To better manage worker risks, an appropriate characterization of the TDI-OA dose-risk relationship is needed. METHODS The literature was reviewed for data suitable for dose-response modeling. Previous study data were fit to models to derive prospective occupational exposure limits (OELs), using benchmark dose (BMD) and low-dose extrapolation approaches. RESULTS Data on eight TDI-exposed populations were suitable for analysis. There were 118 OA cases in a population contributing 13 590 person-years. The BMD-based OEL was 0.4 ppb. The OEL based on low-dose extrapolation to working lifetime extra risk of 1/1000 was 0.3 ppb. CONCLUSIONS This study synthesized epidemiologic data to characterize the TDI-OA dose-risk relationship. This approach yielded prospective OEL estimates below recent recommendations by the American Conference of Governmental Industrial Hygienists, but given significant study limitations, this should be interpreted with caution. Confirmatory research is needed.
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Affiliation(s)
- Robert D. Daniels
- National Institute for Occupational Safety and Health (NIOSH); Cincinnati, Ohio
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14
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Sullivan KM, Enoch SJ, Ezendam J, Sewald K, Roggen EL, Cochrane S. An Adverse Outcome Pathway for Sensitization of the Respiratory Tract by Low-Molecular-Weight Chemicals: Building Evidence to Support the Utility ofIn VitroandIn SilicoMethods in a Regulatory Context. ACTA ACUST UNITED AC 2017. [DOI: 10.1089/aivt.2017.0010] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Kristie M. Sullivan
- Physicians Committee for Responsible Medicine, Washington, District of Columbia
| | - Steven J. Enoch
- School of Pharmacy and Biomolecular Sciences, Liverpool John Moores University, Liverpool, England
| | - Janine Ezendam
- National Institute for Public Health and the Environment (RIVM), Centre for Health Protection, Bilthoven, The Netherlands
| | - Katherina Sewald
- Fraunhofer Institute for Toxicology and Experimental Medicine ITEM, Hannover, Germany
| | - Erwin L. Roggen
- 3Rs Management & Consulting ApS (3RsMC ApS), Lyngby, Denmark
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15
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Balakirski G, Merk HF. Cutaneous allergic drug reactions: update on pathophysiology, diagnostic procedures and differential diagnosic. Cutan Ocul Toxicol 2017; 36:307-316. [DOI: 10.1080/15569527.2017.1319379] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Galina Balakirski
- Department of Dermatology and Allergology, RWTH Aachen University, Aachen, Germany
| | - Hans F. Merk
- Department of Dermatology and Allergology, RWTH Aachen University, Aachen, Germany
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16
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Developing a framework for assessing chemical respiratory sensitization: A workshop report. Regul Toxicol Pharmacol 2016; 80:295-309. [PMID: 27396307 DOI: 10.1016/j.yrtph.2016.06.006] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2016] [Accepted: 06/10/2016] [Indexed: 12/29/2022]
Abstract
Respiratory tract sensitization can have significant acute and chronic health implications. While induction of respiratory sensitization is widely recognized for some chemicals, validated standard methods or frameworks for identifying and characterizing the hazard are not available. A workshop on assessment of respiratory sensitization was held to discuss the current state of science for identification and characterization of respiratory sensitizer hazard, identify information facilitating development of validated standard methods and frameworks, and consider the regulatory and practical risk management needs. Participants agreed on a predominant Th2 immunological mechanism and several steps in respiratory sensitization. Some overlapping cellular events in respiratory and skin sensitization are well understood, but full mechanism(s) remain unavailable. Progress on non-animal approaches to skin sensitization testing, ranging from in vitro systems, -omics, in silico profiling, and structural profiling were acknowledged. Addressing both induction and elicitation phases remains challenging. Participants identified lack of a unifying dose metric as increasing the difficulty of interpreting dosimetry across exposures. A number of research needs were identified, including an agreed list of respiratory sensitizers and other asthmagens, distinguishing between adverse effects from immune-mediated versus non-immunological mechanisms. A number of themes emerged from the discussion regarding future testing strategies, particularly the need for a tiered framework respiratory sensitizer assessment. These workshop present a basis for moving towards a weight-of-evidence assessment.
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17
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Long CM, Marshall NB, Lukomska E, Kashon ML, Meade BJ, Shane H, Anderson SE. A Role for Regulatory T Cells in a Murine Model of Epicutaneous Toluene Diisocyanate Sensitization. Toxicol Sci 2016; 152:85-98. [PMID: 27103660 PMCID: PMC4987710 DOI: 10.1093/toxsci/kfw074] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Toluene diisocyanate (TDI) is a leading cause of chemical-induced occupational asthma which impacts workers in a variety of industries worldwide. Recently, the robust regulatory potential of regulatory T cells (Tregs) has become apparent, including their functional role in the regulation of allergic disease; however, their function in TDI-induced sensitization has not been explored. To elucidate the kinetics, phenotype, and function of Tregs during TDI sensitization, BALB/c mice were dermally exposed (on each ear) to a single application of TDI (0.5-4% v/v) or acetone vehicle and endpoints were evaluated via RT-PCR and flow cytometry. The draining lymph node (dLN) Treg population expanded significantly 4, 7, and 9 days after single 4% TDI exposure. This population was identified using a variety of surface and intracellular markers and was found to be phenotypically heterogeneous based on increased expression of markers including CD103, CCR6, CTLA4, ICOS, and Neuropilin-1 during TDI sensitization. Tregs isolated from TDI-sensitized mice were significantly more suppressive compared with their control counterparts, further supporting a functional role for Tregs during TDI sensitization. Last, Tregs were depleted prior to TDI sensitization and an intensified sensitization response was observed. Collectively, these data indicate that Tregs exhibit a functional role during TDI sensitization. Because the role of Tregs in TDI sensitization has not been previously elucidated, these data contribute to the understanding of the immunologic mechanisms of chemical induced allergic disease.
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MESH Headings
- Animals
- Antigens, CD/immunology
- Antigens, CD/metabolism
- CTLA-4 Antigen/immunology
- CTLA-4 Antigen/metabolism
- Cell Proliferation
- Cells, Cultured
- Dermatitis, Allergic Contact/immunology
- Dermatitis, Allergic Contact/metabolism
- Disease Models, Animal
- Female
- Inducible T-Cell Co-Stimulator Protein/immunology
- Inducible T-Cell Co-Stimulator Protein/metabolism
- Integrin alpha Chains/immunology
- Integrin alpha Chains/metabolism
- Kinetics
- Lymphocyte Activation
- Mice, Inbred BALB C
- Neuropilin-1/immunology
- Neuropilin-1/metabolism
- Phenotype
- Receptors, CCR6/immunology
- Receptors, CCR6/metabolism
- Skin/immunology
- Skin/metabolism
- T-Lymphocytes, Regulatory/immunology
- T-Lymphocytes, Regulatory/metabolism
- Toluene 2,4-Diisocyanate
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Affiliation(s)
- Carrie Mae Long
- *Allergy and Clinical Immunology Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Morgantown, West Virginia 26505 Immunology and Microbial Pathogenesis Graduate Program, West Virginia University School of Medicine, Morgantown, West Virginia 26505
| | - Nikki B Marshall
- *Allergy and Clinical Immunology Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Morgantown, West Virginia 26505
| | - Ewa Lukomska
- *Allergy and Clinical Immunology Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Morgantown, West Virginia 26505
| | - Michael L Kashon
- Biostatics and Epidemiology Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Morgantown, West Virginia 26505
| | - B Jean Meade
- *Allergy and Clinical Immunology Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Morgantown, West Virginia 26505
| | - Hillary Shane
- *Allergy and Clinical Immunology Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Morgantown, West Virginia 26505
| | - Stacey E Anderson
- *Allergy and Clinical Immunology Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Morgantown, West Virginia 26505
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18
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Wisnewski AV, Liu J, Nassar AF. In vitro cleavage of diisocyanate-glutathione conjugates by human gamma-glutamyl transpeptidase-1. Xenobiotica 2015; 46:726-32. [PMID: 26678254 DOI: 10.3109/00498254.2015.1118576] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Isocyanates differ from many other xenobiotics in their ability to form S-linked conjugates with glutathione (GSH) through direct nucleophilic addition reactions (e.g. without enzymatic "preactivation" and/or transferase activity), potentially predisposing them to metabolism via the mercapturic acid pathway. In vivo, mono-isocyanates are metabolized via the mercapturic acid pathway and excreted as N-acetylated cysteine conjugates, however, the metabolism of di-isocyanates remains unclear. We assessed the ability of purified human gamma-glutamyl transpeptidase-1 (GGT-1), a primary enzyme of the mercapturic acid pathway, to cleave S-linked GSH conjugates of 4,4'-methylene diphenyl diisocyanate (MDI) and 1,6-hexamethylene diisocyanate (HDI), two widely used industrial chemicals. A combination of liquid chromatography (LC), tandem mass spectrometry (MS/MS) and hydrogen-deuterium exchange studies confirmed GGT-1 mediated formation of the 607.2 and 525.2 m/z (M + H)(+) ions corresponding to bis(cys-gly)-MDI and bis(cys-gly)-HDI, respectively, the cleavage products expected from the corresponding bis(GSH)-diisocyanate conjugates. Additional intermediate metabolites and mono(cys-gly)-conjugates with partially hydrolyzed diisocyanate were also observed. Consistent with GGT enzyme kinetics, metabolism proceeded more rapidly under conditions that favored transpeptidation versus hydrolytic mechanisms of cleavage. Together the data demonstrate the capacity of human GGT-1 to cleave GSH conjugates of both aromatic and aliphatic diisocyanates, suggesting a potential role in their metabolism.
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Affiliation(s)
- Adam V Wisnewski
- a Department of Medicine , Yale University School of Medicine , New Haven , CT , USA
| | - Jian Liu
- a Department of Medicine , Yale University School of Medicine , New Haven , CT , USA
| | - Ala F Nassar
- a Department of Medicine , Yale University School of Medicine , New Haven , CT , USA
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19
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Immunochemical detection of the occupational allergen, methylene diphenyl diisocyanate (MDI), in situ. J Immunol Methods 2015; 429:60-5. [PMID: 26690039 DOI: 10.1016/j.jim.2015.12.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Revised: 12/11/2015] [Accepted: 12/11/2015] [Indexed: 01/08/2023]
Abstract
Diisocyanate chemicals essential to polyurethane production are a well-recognized cause of occupational asthma. The pathogenesis of diisocyanate-induced asthma, including the pathways by which the chemical is taken up and its distribution in exposed tissue, especially the lung, remains unclear. We developed an antiserum with specificity for methylene diphenyl diisocyanate (MDI) the most abundantly produced and utilized diisocyanate world-wide, and established its ability to detect MDI in situ. Polyclonal MDI-specific IgG was induced by immunizing rabbits with MDI-conjugated to keyhole limpet hemocyanin (KLH) emulsified in complete Freund's adjuvant, followed by two booster injections with incomplete Freund's adjuvant. The antiserum contains IgG that recognize a variety of different MDI conjugated proteins, but not unconjugated or mock exposed proteins by dot blot analysis. The antiserum further demonstrates specificity for proteins conjugated with MDI, but not other commonly used diisocyanates. Immunochemical studies with cytospun airway cells and formalin-fixed paraffin embedded lung tissue sections from mice intranasally exposed to MDI (as reversibly reactive glutathione conjugates, e.g. GSH-MDI) demonstrated the antiserum's ability to detect MDI in tissue samples. The data demonstrate penetration of MDI into the lower airways, localized deposition in the epithelial region surrounding airways, and uptake by alveolar macrophages. The new immunochemical reagent should be useful for further studies delineating the uptake and tissue distribution of MDI, especially as it relates to adverse health effects from exposure.
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20
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Toluene diisocyanate and methylene diphenyl diisocyanate: asthmatic response and cross-reactivity in a mouse model. Arch Toxicol 2015; 90:1709-17. [PMID: 26468151 DOI: 10.1007/s00204-015-1606-6] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Accepted: 09/21/2015] [Indexed: 10/22/2022]
Abstract
Both 2,4-toluene diisocyanate (TDI) and 4,4-methylene diphenyl diisocyanate (MDI) can cause occupational asthma. In this study, we optimized our mouse model of chemical-induced asthma in the C57Bl/6 mice strain using the model agent TDI. Furthermore, we validated MDI in this mouse model and investigated whether cross-reactivity between TDI and MDI is present. On days 1 and 8, C57Bl/6 mice were dermally treated (20 µl/ear) with 3 % MDI, 2 % TDI or the vehicle acetone olive oil (AOO) (3:2). On day 15, they received a single oropharyngeal challenge with 0.04 % MDI, 0.01 % TDI or the vehicle AOO (4:1). One day later, airway hyperreactivity (AHR) and pulmonary inflammation in the bronchoalveolar lavage (BAL) were assessed. Furthermore, total serum IgE levels, lymphocyte subpopulations in auricular lymph nodes and cytokine levels in supernatants of lymphocytes were measured. Both dermal sensitization with TDI or MDI resulted in increased total serum IgE levels along with T and B cell proliferation in the auricular lymph nodes. The auricular lymphocytes showed an increased release of both Th2 and Th1 cytokines. Mice sensitized and challenged with either TDI or MDI showed AHR, along with a predominant neutrophil lung inflammation. Mice sensitized with MDI and challenged with TDI or the other way around showed no AHR, nor BAL inflammation. Both TDI and MDI are able to induce an asthma-like response in this mouse model. However, cross-reactivity between both diisocyanates remained absent.
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21
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Maier A, Vincent MJ, Parker A, Gadagbui BK, Jayjock M. A tiered asthma hazard characterization and exposure assessment approach for evaluation of consumer product ingredients. Regul Toxicol Pharmacol 2015; 73:903-13. [PMID: 26416168 DOI: 10.1016/j.yrtph.2015.09.028] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2015] [Revised: 09/21/2015] [Accepted: 09/22/2015] [Indexed: 11/19/2022]
Abstract
Asthma is a complex syndrome with significant consequences for those affected. The number of individuals affected is growing, although the reasons for the increase are uncertain. Ensuring the effective management of potential exposures follows from substantial evidence that exposure to some chemicals can increase the likelihood of asthma responses. We have developed a safety assessment approach tailored to the screening of asthma risks from residential consumer product ingredients as a proactive risk management tool. Several key features of the proposed approach advance the assessment resources often used for asthma issues. First, a quantitative health benchmark for asthma or related endpoints (irritation and sensitization) is provided that extends qualitative hazard classification methods. Second, a parallel structure is employed to include dose-response methods for asthma endpoints and methods for scenario specific exposure estimation. The two parallel tracks are integrated in a risk characterization step. Third, a tiered assessment structure is provided to accommodate different amounts of data for both the dose-response assessment (i.e., use of existing benchmarks, hazard banding, or the threshold of toxicological concern) and exposure estimation (i.e., use of empirical data, model estimates, or exposure categories). Tools building from traditional methods and resources have been adapted to address specific issues pertinent to asthma toxicology (e.g., mode-of-action and dose-response features) and the nature of residential consumer product use scenarios (e.g., product use patterns and exposure durations). A case study for acetic acid as used in various sentinel products and residential cleaning scenarios was developed to test the safety assessment methodology. In particular, the results were used to refine and verify relationships among tiered approaches such that each lower data tier in the approach provides a similar or greater margin of safety for a given scenario.
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Affiliation(s)
- Andrew Maier
- Department of Environmental Health, University of Cincinnati College of Medicine, Cincinnati, OH, USA.
| | - Melissa J Vincent
- Department of Environmental Health, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - Ann Parker
- Department of Environmental Health, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - Bernard K Gadagbui
- Department of Environmental Health, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - Michael Jayjock
- The LifeLine Group, 4610 Quarter Charge Dr, Annandale, VA, 22003, USA
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22
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Pauluhn J. Analysis of the interrelationship of the pulmonary irritation and elicitation thresholds in rats sensitized with 1,6-hexamethylene diisocyanate (HDI). Inhal Toxicol 2015; 27:191-206. [PMID: 25924102 PMCID: PMC4496806 DOI: 10.3109/08958378.2015.1026619] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
This paper summarizes a range of experimental data central for developing a science-based approach for hazard identification of monomeric and polymeric aliphatic 1,6-hexamethylene diisocyanate (HDI). The dose–response curve of HDI-induced pulmonary responses in naïve or dermally sensitized rats after one or several inhalation priming exposures was examined in the Brown Norway (BN) rat asthma model. Emphasis was directed to demonstrate the need and the difficulty in selecting an appropriate pulmonary dose when much of the inhaled chemically reactive vapor may concentration dependently be retained in the upper airways of obligate nose-breathing rats. The course taken acknowledges the experimental challenges in identifying an elicitation threshold for HDI-monomer near or above the saturated vapor concentration or in the presence of a HDI-polymer aerosol. The inhalation threshold dose on elicitation was determined based on a fixed concentration (C) × variable exposure duration (t) protocol for improving inhalation dosimetry of the lower airways. Neutrophilic granulocytes (PMN) in bronchoalveolar lavage (BAL) fluid in equally inhalation primed naïve and dermally sensitized rats were used to define the inhalation elicitation threshold C × t. Sensitized rats elaborated markedly increased PMN challenged sensitized rats relative to equally challenged naïve rats at 5625 mg HDI/m3 × min (75 mg/m3 for 75 min). PMN were essentially indistinguishable at 900 mg HDI/m3 × min. By applying adjustment factors accounting for both inter-species differences in inhalation dosimetry and intra-species susceptibility, the workplace human-equivalent threshold C × t was estimated to be in the range of the current ACGIH TLV® of HDI. Thus, this rat “asthma” model was suitable to demonstrate elicitation thresholds for HDI-vapor after one or several inhalation priming exposures and seems to be suitable to derive occupational exposure values (OELs) for diisocyanates in general.
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Affiliation(s)
- Jürgen Pauluhn
- Bayer Pharma AG, Experimental Toxicology , Wuppertal , Germany (retired) and
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23
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Transfluthrin: Comparative efficacy and toxicity of reference and generic versions. Regul Toxicol Pharmacol 2015; 71:78-92. [DOI: 10.1016/j.yrtph.2014.11.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2014] [Revised: 11/01/2014] [Accepted: 11/03/2014] [Indexed: 11/19/2022]
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Dotson GS, Maier A, Siegel PD, Anderson SE, Green BJ, Stefaniak AB, Codispoti CD, Kimber I. Setting Occupational Exposure Limits for Chemical Allergens--Understanding the Challenges. JOURNAL OF OCCUPATIONAL AND ENVIRONMENTAL HYGIENE 2015; 12 Suppl 1:S82-98. [PMID: 26583909 PMCID: PMC4685595 DOI: 10.1080/15459624.2015.1072277] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Chemical allergens represent a significant health burden in the workplace. Exposures to such chemicals can cause the onset of a diverse group of adverse health effects triggered by immune-mediated responses. Common responses associated with workplace exposures to low molecular weight (LMW) chemical allergens range from allergic contact dermatitis to life-threatening cases of asthma. Establishing occupational exposure limits (OELs) for chemical allergens presents numerous difficulties for occupational hygiene professionals. Few OELs have been developed for LMW allergens because of the unique biological mechanisms that govern the immune-mediated responses. The purpose of this article is to explore the primary challenges confronting the establishment of OELs for LMW allergens. Specific topics include: (1) understanding the biology of LMW chemical allergies as it applies to setting OELs; (2) selecting the appropriate immune-mediated response (i.e., sensitization versus elicitation); (3) characterizing the dose (concentration)-response relationship of immune-mediated responses; (4) determining the impact of temporal exposure patterns (i.e., cumulative versus acute exposures); and (5) understanding the role of individual susceptibility and exposure route. Additional information is presented on the importance of using alternative exposure recommendations and risk management practices, including medical surveillance, to aid in protecting workers from exposures to LMW allergens when OELs cannot be established.
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Affiliation(s)
- G. S. Dotson
- Education and Information Division, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, Cincinnati, Ohio
- Address correspondence to G.S. Dotson, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, Education and Information Division, 1090 Tusculum Avenue, MS C-32, CincinnatiOhio45226. E-mail:
| | - A. Maier
- Education and Information Division, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, Cincinnati, Ohio
- College of Medicine, University of Cincinnati, Cincinnati, Ohio
| | - P. D. Siegel
- Health Effects Laboratory Division, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, Morgantown, West Virginia
| | - S. E. Anderson
- Health Effects Laboratory Division, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, Morgantown, West Virginia
| | - B. J. Green
- Health Effects Laboratory Division, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, Morgantown, West Virginia
| | - A. B. Stefaniak
- Respiratory Health Division, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, Morgantown, West Virginia
| | - C. D. Codispoti
- Department of Immunology and Microbiology, Rush University Medical Center, Chicago, Illinois
| | - I. Kimber
- Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom
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