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Viability of cultured human skin cells treated with 1,6-hexamethylene diisocyanate monomer and its oligomer isocyanurate in different culture media. Sci Rep 2021; 11:23804. [PMID: 34893638 PMCID: PMC8664849 DOI: 10.1038/s41598-021-02811-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Accepted: 11/23/2021] [Indexed: 11/17/2022] Open
Abstract
The isocyanate monomer 1,6-hexamethylene diisocyanate (HDI) and one of its trimers, HDI isocyanurate, are airway and skin sensitizers contained in polyurethane paint. The toxic response of cultured skin cells to these compounds was measured by evaluating the isocyanate concentrations at which 50% of the cells die (i.e., lethal concentration 50%, LC50) because the relative toxicity of each form of HDI should be considered when exposure limits of HDI-based paints are set. By using a luminescent ATP-viability assay, we compared the cytotoxic effects of HDI monomer and HDI isocyanurate on cultured human skin cells (keratinocytes, fibroblasts, and melanocytes) after 4-h isocyanate exposures using culture media with varying levels of nutrients in order to also determine the effects of media composition on isocyanate toxicity. Before analysis, experimental wells were normalized to controls containing cells that were cultured with the same vehicle and media. The measured mean LC50 values ranged from 5 to 200 µM across the experimental conditions, in which HDI isocyanurate in protein-devoid media was the most toxic to cells, producing the lowest LC50 values. For HDI monomer, keratinocytes were the most resistant to its toxicity and melanocytes were the most susceptible. However, when exposed to HDI isocyanurate, the opposite was observed, with melanocytes being the most resilient and the keratinocytes and fibroblasts were more susceptible. Depending on the type of skin cells, dose–response data indicated that HDI isocyanurate was 2–6 times more toxic than HDI monomer when using protein-devoid media whereas HDI isocyanurate was 4–13 times more toxic than HDI monomer when protein-rich media was used. Therefore, if the protein-devoid saline medium alone were used for these experiments, then a significant under-estimation of their relative toxicities in protein-rich environments would have resulted. This difference is because HDI monomer toxicity was more attenuated by the presence of protein in the culture media than HDI isocyanurate toxicity. Thus, conclusions based on comparative toxicity studies and consequent inference applied to potential human toxicity can be affected by in vitro culture media conditions. The physiochemical difference in reactivity of the two forms of HDI to biological molecules most likely explains the observed toxicity differences and may have implications for skin penetration, adverse effects like skin sensitization, and systemic responses like asthma. Future studies are warranted to investigate differences in the biological availability, cellular toxicity, and immunologic sensitization mechanisms for HDI monomer and HDI isocyanurate.
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Ceballos DM, Reeb-Whitaker C, Sasakura M, Dills R, Yost MG. Protection efficacy of gloves against components of the solvent in a sprayed isocyanate coating utilizing a reciprocating permeation panel. ANNALS OF OCCUPATIONAL HYGIENE 2014; 59:358-72. [PMID: 25452292 DOI: 10.1093/annhyg/meu099] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
OBJECTIVES Determine protection effectiveness of 5-mil natural rubber latex (0.13-mm), 5-mil nitrile rubber (0.13-mm), and 13-mil butyl rubber (0.33-mm) glove materials against solvents present in a commonly used automotive clear coat formulation using a novel permeation panel. The latex and nitrile gloves were the type commonly used by local autobody spray painters. METHODS Glove materials were tested by spraying an automotive clear coat onto an automated reciprocating permeation panel (permeation panel II). Temperature, relative humidity, and spray conditions were controlled to optimize clear coat loading homogeneity as evaluated by gravimetric analysis. Solvent permeation was measured using charcoal cloth analyzed by the National Institute for Occupational Safety and Health 1501 method. RESULTS Natural rubber latex allowed 3-5 times the permeation of solvents relative to nitrile rubber for all 10 solvents evaluated: ethyl benzene, 2-heptanone, 1-methoxy-2-propyl acetate, o-xylene, m-xylene, p-xylene, n-butyl acetate, methyl isobutyl ketone, petroleum distillates, and toluene. There is a distinct behavior in solvent permeation before and after the coating dry time. Solvent permeation increased steadily before coating dry time and remained fairly constant after coating dry time. Butyl was not permeated by any of the solvents under the conditions tested. CONCLUSIONS Commonly used 5-mil thick (0.13-mm) latex and nitrile gloves were ineffective barriers to solvents found in a commonly used clear coat formulation. Conversely, 13-mil (0.33-mm) butyl gloves were found to be protective against all solvents in the clear coat formulation.
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Affiliation(s)
- Diana M Ceballos
- 1.Department of Environmental and Occupational Health Sciences, University of Washington, Box 357234, Seattle, WA 98195-7234, USA
| | - Carolyn Reeb-Whitaker
- 2.Safety and Health Assessment and Research for Prevention (SHARP) Program, Washington State Department of Labor and Industries, PO Box 44330, Olympia, WA 98504-4330, USA
| | - Miyoko Sasakura
- 1.Department of Environmental and Occupational Health Sciences, University of Washington, Box 357234, Seattle, WA 98195-7234, USA
| | - Russell Dills
- 1.Department of Environmental and Occupational Health Sciences, University of Washington, Box 357234, Seattle, WA 98195-7234, USA
| | - Michael G Yost
- 1.Department of Environmental and Occupational Health Sciences, University of Washington, Box 357234, Seattle, WA 98195-7234, USA
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Brosseau LM, Bejan A, Parker DL, Skan M, Xi M. Workplace safety and health programs, practices, and conditions in auto collision repair businesses. JOURNAL OF OCCUPATIONAL AND ENVIRONMENTAL HYGIENE 2014; 11:354-65. [PMID: 24274827 DOI: 10.1080/15459624.2013.866714] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
This article describes the results of a pre-intervention safety assessment conducted in 49 auto collision repair businesses and owners' commitments to specific improvements. A 92-item standardized audit tool employed interviews, record reviews, and observations to assess safety and health programs, training, and workplace conditions. Owners were asked to improve at least one-third of incorrect, deficient, or missing (not in compliance with regulations or not meeting best practice) items, of which a majority were critical or highly important for ensuring workplace safety. Two-thirds of all items were present, with the highest fraction related to electrical safety, machine safety, and lockout/tagout. One-half of shops did not have written safety programs and had not conducted recent training. Many had deficiencies in respiratory protection programs and practices. Thirteen businesses with a current or past relationship with a safety consultant had a significantly higher fraction of correct items, in particular related to safety programs, up-to-date training, paint booth and mixing room conditions, electrical safety, and respiratory protection. Owners selected an average of 58% of recommended improvements; they were most likely to select items related to employee Right-to-Know training, emergency exits, fire extinguishers, and respiratory protection. They were least likely to say they would improve written safety programs, stop routine spraying outside the booth, or provide adequate fire protection for spray areas outside the booth. These baseline results suggest that it may be possible to bring about workplace improvements using targeted assistance from occupational health and safety professionals.
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Affiliation(s)
- L M Brosseau
- a School of Public Health , University of Minnesota , Minneapolis , Minnesota
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Parker DL, Brosseau LM, Bejan A, Skan M, Xi M. Understanding safety climate in small automobile collision repair shops. Am J Ind Med 2014; 57:78-86. [PMID: 23955439 DOI: 10.1002/ajim.22235] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/10/2013] [Indexed: 11/05/2022]
Abstract
BACKGROUND In the United States, approximately 236,000 people work in 37,600 auto collision-repair businesses. Workers in the collision-repair industry may be exposed to a wide range of physical and chemical hazards. METHODS This manuscript examines the relationship of safety climate as reported by collision repair shop workers and owners to: (1) an independent business safety assessment, and (2) employee self-reported work practices. The study was conducted in the Twin Cities metropolitan area. RESULTS A total of 199 workers from 49 collision shops completed a survey of self-reported work practices and safety climate. Surveys were completed by an owner or manager in all but three shops. In general, self-reported work practices were poor. Workers' scores on safety climate were uniformly lower than those of owners. For workers, there was no correlation between how well the business scored on an independent audit of business safety practices and the safety climate measures they reported. For owners, however, there was a positive correlation between safety climate scores and the business safety assessment. For workers, safety rules and procedures were associated with improved work practices for those engaged in both painting-related and body technician-related activities. CONCLUSIONS The enforcement of safety rules and procedures emerged as a strong factor positively affecting self-reported work practices. These findings identify a simple, cost effective path to reducing hazards in small workplaces.
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Affiliation(s)
- David L. Parker
- Health Research; Park Nicollet Institute; 3800 Park Nicollet Blvd. Minneapolis Minnesota
| | - Lisa M. Brosseau
- School of Public Health, University of Illinois; Chicago Illinois
| | - Anca Bejan
- Health Research; Park Nicollet Institute; 3800 Park Nicollet Blvd. Minneapolis Minnesota
| | - Maryellen Skan
- Health Research; Park Nicollet Institute; 3800 Park Nicollet Blvd. Minneapolis Minnesota
| | - Min Xi
- Health Research; Park Nicollet Institute; 3800 Park Nicollet Blvd. Minneapolis Minnesota
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Ceballos D, Reeb-Whitaker C, Glazer P, Murphy-Robinson H, Yost M. Understanding factors that influence protective glove use among automotive spray painters. JOURNAL OF OCCUPATIONAL AND ENVIRONMENTAL HYGIENE 2014; 11:306-313. [PMID: 24215135 PMCID: PMC5514320 DOI: 10.1080/15459624.2013.862592] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Dermal contact with isocyanate-based coatings may lead to systemic respiratory sensitization. The most common isocyanates found in sprayed automotive coatings are monomeric and oligomeric 1,6-hexamethylene diisocyanate (HDI) and isophorone diisocyanate (IPDI). Most spray painters use thin (4-5 mil) latex gloves that are not effective at preventing dermal exposures when spraying isocyanate paints. Personal interviews with collision repair industry personnel and focus groups with spray painters were held to characterize risk awareness, to examine perceptions and challenges concerning protective glove use and selection, and to generate ideas for protective glove use interventions. The most popular gloves among spray painters were thin (4-5 mil) and thick (14 mil) latex. We found that medium to thick (6-8 mil) nitrile were not always perceived as comfortable and were expected to be more expensive than thin (4-5 mil) latex gloves. Of concern is the user's difficulty in distinguishing between nitrile and latex gloves; latex gloves are now sold in different colors including blue, which has traditionally been associated with nitrile gloves. Even though spray painters were familiar with the health hazards related to working with isocyanate paints, most were not always aware that dermal exposure to isocyanates could contribute to the development of occupational asthma. There is a need for more research to identify dermal materials that are protective against sprayed automotive coatings. Automotive spray painters and their employers need to be educated in the selection and use of protective gloves, specifically on attributes such as glove material, color, and thickness.
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Affiliation(s)
- Diana Ceballos
- Department of Environmental and Occupational Health Sciences University of Washington, Box 357234, Seattle, Washington 98195-7234, USA
| | - Carolyn Reeb-Whitaker
- Safety & Health Assessment & Research for Prevention (SHARP) Program, Washington State Department of Labor and Industries, PO Box 44330, Olympia, Washington 98504-4330, USA
| | - Patricia Glazer
- Gilmore Research Group, 2101 4th Avenue, Seattle, Washington 98121-2300
| | - Helen Murphy-Robinson
- Department of Environmental and Occupational Health Sciences University of Washington, Box 357234, Seattle, Washington 98195-7234, USA
| | - Michael Yost
- Department of Environmental and Occupational Health Sciences University of Washington, Box 357234, Seattle, Washington 98195-7234, USA
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Ceballos DM, Sasakura M, Reeb-Whitaker C, Broadwater K, Milbauer M, Crampton R, Dills R, Yost MG. Testing of glove efficacy against sprayed isocyanate coatings utilizing a reciprocating permeation panel. ACTA ACUST UNITED AC 2013; 58:50-9. [PMID: 24366204 DOI: 10.1093/annhyg/met060] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
OBJECTIVES Modify a permeation panel to evaluate dermal protective clothing for resistance to sprayed coatings with minimal variability in spray paint loading across the test panel. Determine isocyanate protection effectiveness of natural rubber latex (5 mil or 0.13mm), nitrile rubber (5 mil or 0.13mm), and butyl rubber (13 mil or 0.33mm) glove materials against a commonly used automotive clear coat formulation. The latex and nitrile gloves were the type used by the local autobody spray painters. METHODS Glove materials were tested by spraying paint onto an automated reciprocating permeation panel (permeation panel II). Temperature, relative humidity, and spray conditions were controlled to optimize paint loading homogeneity as evaluated by gravimetric analysis. Isocyanate permeation was measured using 1-(2-pyridyl)-piperazine-coated fiber-glass filters analyzed by a modified version of the OSHA 42/PV2034 methods. RESULTS Latex exhibited a higher permeation rate compared with nitrile for isocyanates (1,6-hexamethylene diisocyanate (HDI) and isophorone diisocyanate monomers) and both materials presented permeation at all of the time points suggesting a fast isocyanate breakthrough. Butyl material exhibited no permeation or breakthrough for isocyanates under the tested conditions. The spray application at 69±8°F was optimally homogeneous at 45±0.5mg weight of dry clear coat per 5cm(2). CONCLUSIONS The permeation panel II is a reliable method to assess dermal protective clothing performance against polymerizing coatings. Commonly used 5-mil (0.13-mm) latex and nitrile gloves were determined to be ineffective barriers against the isocyanates found in a commonly used clear-coat formulation while butyl gloves were protective.
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Affiliation(s)
- Diana M Ceballos
- Department of Environmental and Occupational Health Sciences, University of Washington, Box 357234, Seattle, WA 98195-7234, USA
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Tran JQ, Ceballos DM, Dills RL, Yost MG, Morgan MS. Transport of a solvent mixture across two glove materials when applied in a paint matrix. ARCHIVES OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2012; 63:169-176. [PMID: 22434453 DOI: 10.1007/s00244-012-9758-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2011] [Accepted: 02/27/2012] [Indexed: 05/31/2023]
Abstract
The transport of mixed paint solvents through natural rubber latex (4 mil) and nitrile rubber (5 mil) gloves was evaluated after spray application of the paint formulation directly on the glove surface. Glove materials and thicknesses were those selected by the majority of spray painters in the local automobile repair industry. A flat panel containing glove specimens mounted in multiple permeation cells permitted evaporation of solvents from the applied paint and incorporated a solid sorbent receiving medium for measuring glove membrane transport. The panel was sprayed in a paint booth to simulate use conditions. Charcoal cloth under the glove adsorbed transported solvents, which were quantified by gas chromatography. For each solvent component, results were expressed as mass transported through the glove relative to the mass applied, per unit area, during 30 min after spray application. The paint formulation contained ketones, acetates, and aromatics. Natural rubber latex allowed 6-10 times the transport of solvents relative to nitrile rubber for all eight solvent components: methyl ethyl ketone, toluene, styrene, ethyl benzene, xylene isomers, and 2-heptanone. m-Xylene showed the largest difference in transport between the two glove materials. This solvent also had the highest transport for each material. The results indicate that nitrile rubber gloves offer somewhat greater chemical resistance to all eight solvents studied compared with natural rubber latex gloves, regardless of the chemical properties of the individual solvent components. However, it must be emphasized that neither of the glove materials, in the thicknesses used in this study, provide adequate protection when exposed by direct spray painting. Simulation of realistic spray conditions may offer a source of useful information on the performance of chemical protective gloves because it accounts for solvent evaporation and the effect of paint polymerization after application on glove transport.
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Affiliation(s)
- Jackelin Q Tran
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, 98195-7234, USA
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Reeb-Whitaker C, Whittaker SG, Ceballos DM, Weiland EC, Flack SL, Fent KW, Thomasen JM, Trelles Gaines LG, Nylander-French LA. Airborne isocyanate exposures in the collision repair industry and a comparison to occupational exposure limits. JOURNAL OF OCCUPATIONAL AND ENVIRONMENTAL HYGIENE 2012; 9:329-39. [PMID: 22500941 PMCID: PMC4075771 DOI: 10.1080/15459624.2012.672871] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Isocyanate exposure was evaluated in 33 spray painters from 25 Washington State autobody shops. Personal breathing zone samples (n = 228) were analyzed for isophorone diisocyanate (IPDI) monomer, 1,6-hexamethylene diisocyanate (HDI) monomer, IPDI polyisocyanate, and three polyisocyanate forms of HDI. The objective was to describe exposures to isocyanates while spray painting, compare them with short-term exposure limits (STELs), and describe the isocyanate composition in the samples. The composition of polyisocyanates (IPDI and HDI) in the samples varied greatly, with maximum amounts ranging from up to 58% for HDI biuret to 96% for HDI isocyanurate. There was a significant inverse relationship between the percentage composition of HDI isocyanurate to IPDI and to HDI uretdione. Two 15-min STELs were compared: (1) Oregon's Occupational Safety and Health Administration (OR-OSHA) STEL of 1000 μg/m(3) for HDI polyisocyanate, and (2) the United Kingdom's Health and Safety Executive (UK-HSE) STEL of 70 μg NCO/m(3) for all isocyanates. Eighty percent of samples containing HDI polyisocyanate exceeded the OR-OSHA STEL while 98% of samples exceeded the UK-HSE STEL. The majority of painters (67%) wore half-face air-purifying respirators while spray painting. Using the OR-OSHA and the UK-HSE STELs as benchmarks, 21% and 67% of painters, respectively, had at least one exposure that exceeded the respirator's OSHA-assigned protection factor. A critical review of the STELs revealed the following limitations: (1) the OR-OSHA STEL does not include all polyisocyanates, and (2) the UK-HSE STEL is derived from monomeric isocyanates, whereas the species present in typical spray coatings are polyisocyanates. In conclusion, the variable mixtures of isocyanates used by autobody painters suggest that an occupational exposure limit is required that includes all polyisocyanates. Despite the limitations of the STELs, we determined that a respirator with an assigned protection factor of 25 or greater is required to protect against isocyanate exposures during spray painting. Consequently, half-face air-purifying respirators, which are most commonly used and have an assigned protection factor of 10, do not afford adequate respiratory protection.
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Affiliation(s)
- Carolyn Reeb-Whitaker
- Safety & Health Assessment & Research for Prevention Program, Washington State Department of Labor & Industries, Tumwater, Washington, USA.
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