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Riley EA, Carpenter EE, Ramsay J, Zamzow E, Pyke C, Paulsen MH, Sheppard L, Spear TM, Seixas NS, Stephenson DJ, Simpson CD. Evaluation of 1-Nitropyrene as a Surrogate Measure for Diesel Exhaust. Ann Work Expo Health 2019; 62:339-350. [PMID: 29300809 DOI: 10.1093/annweh/wxx111] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Accepted: 12/06/2017] [Indexed: 11/14/2022] Open
Abstract
We investigated the viability of particle bound 1-nitropyrene (1-NP) air concentration measurements as a surrogate of diesel exhaust (DE) exposure, as compared with industry-standard elemental carbon (EC) and total carbon (TC) measurements. Personal exposures are reported for 18 employees at a large underground metal mine during four different monitoring campaigns. Full-shift personal air exposure sampling was conducted using a Mine Safety and Health Administration (MSHA) compliant diesel particulate matter (DPM) impactor cassette downstream of a GS-1 cyclone pre-selector. Each DPM filter element was analyzed for EC and organic carbon (OC) using NIOSH Method 5040. After EC and OC analysis, the remaining portion of each DPM filter was analyzed for 1-NP using liquid chromatography tandem mass spectrometry (LC/MS/MS). We observed high correlations between the quantiles of 1-NP and EC exposures across 10 different work shift task groups (r = 0.87 to 0.96), and a linear relationship with a slope between 6.0 to 6.9 pg 1-NP per µg EC. However, correlation between 1-NP and EC was weak (r =0.34) for the 91 individual sample pairs due to low EC concentrations and possible heterogeneity of DE composition. While both 1-NP and EC differentiated between high and low exposure groups categorized by job location, measurements of 1-NP, but not EC further differentiated between specific job activities. Repeated measurements on individual subjects verified the relationship between 1-NP and EC and demonstrated substantial within-subject variability in exposure. The detection limit of TC air concentration ranged between 18 and 28 µg m-3 and was limited by OC contamination of the quartz filters in the MSHA compliant DPM samplers.
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Affiliation(s)
- Erin A Riley
- Department of Environmental and Occupational Health Sciences, School of Public Health, University of Washington, Seattle, WA, USA
| | - Emily E Carpenter
- Department of Environmental and Occupational Health Sciences, School of Public Health, University of Washington, Seattle, WA, USA
| | - Joemy Ramsay
- Department of Environmental and Occupational Health Sciences, School of Public Health, University of Washington, Seattle, WA, USA
| | - Emily Zamzow
- Department of Environmental and Occupational Health Sciences, School of Public Health, University of Washington, Seattle, WA, USA.,Department of Community and Environmental Health, School of Allied Health Sciences, College of Health Sciences, Boise State University, Boise, ID, USA
| | - Christopher Pyke
- Department of Environmental and Occupational Health Sciences, School of Public Health, University of Washington, Seattle, WA, USA
| | - Michael H Paulsen
- Department of Environmental and Occupational Health Sciences, School of Public Health, University of Washington, Seattle, WA, USA
| | - Lianne Sheppard
- Department of Environmental and Occupational Health Sciences, School of Public Health, University of Washington, Seattle, WA, USA.,Department of Biostatistics, School of Public Health, University of Washington, Seattle, WA, USA
| | - Terry M Spear
- Safety, Health, and Industrial Hygiene Department, School of Mines and Engineering, Montana Tech, Butte, MT, USA
| | - Noah S Seixas
- Department of Environmental and Occupational Health Sciences, School of Public Health, University of Washington, Seattle, WA, USA
| | - Dale J Stephenson
- Department of Community and Environmental Health, School of Allied Health Sciences, College of Health Sciences, Boise State University, Boise, ID, USA
| | - Christopher D Simpson
- Department of Environmental and Occupational Health Sciences, School of Public Health, University of Washington, Seattle, WA, USA
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Michaels MA, Sherwood S, Kidwell M, Allsbrook MJ, Morrison SA, Rutan SC, Carpenter EE. Quantitative model for prediction of hydrodynamic size of nonionic reverse micelles. J Colloid Interface Sci 2007; 311:70-6. [PMID: 17391691 DOI: 10.1016/j.jcis.2007.02.085] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2006] [Revised: 02/20/2007] [Accepted: 02/22/2007] [Indexed: 11/15/2022]
Abstract
The sizes of nonionic reverse micelles were investigated as a function of the molecular structure of the surfactant, the type of oil, the total concentration of surfactant [NP], the ratio of surfactant to total surfactant (r), the water to surfactant molar ratio (omega), temperature, salt concentration, and polar phase. The basis of our investigation was a mixture of nonylphenol polyethoxylates--NP4 and NP7, various polar phases, and several oils. Micelle sizes were determined using dynamic light scattering (DLS). A central composite experimental design was used to quantitatively model micelle size as a function of omega, surfactant concentration, and r. The model has demonstrated the capability of predicting the mean diameter of micelles from 4 to 13 with a precision of +/-2 nm as measured by DLS. This quantitative correlation between the size of reverse micelles and the synthetic variables provides the foundation for choosing experimental conditions to control reverse micelle size. In turn, this allows control of the size of nanoparticles synthesized within them.
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Affiliation(s)
- M A Michaels
- Department of Chemistry, Virginia Commonwealth University, Richmond, 1001 West Main Street, Richmond, VA 23284, USA
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