Last data update: May 06, 2024. (Total: 46732 publications since 2009)
Records 1-4 (of 4 Records) |
Query Trace: Chirila M[original query] |
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A comparison of two laboratories for the measurement of wood dust using button sampler and diffuse reflection infrared Fourier-transform spectroscopy (DRIFTS)
Chirila MM , Sarkisian K , Andrew ME , Kwon CW , Rando RJ , Harper M . Ann Occup Hyg 2014 59 (3) 336-46 The current measurement method for occupational exposure to wood dust is by gravimetric analysis and is thus non-specific. In this work, diffuse reflection infrared Fourier transform spectroscopy (DRIFTS) for the analysis of only the wood component of dust was further evaluated by analysis of the same samples between two laboratories. Field samples were collected from six wood product factories using 25-mm glass fiber filters with the Button aerosol sampler. Gravimetric mass was determined in one laboratory by weighing the filters before and after aerosol collection. Diffuse reflection mid-infrared spectra were obtained from the wood dust on the filter which is placed on a motorized stage inside the spectrometer. The metric used for the DRIFTS analysis was the intensity of the carbonyl band in cellulose and hemicellulose at ~1735cm-1. Calibration curves were constructed separately in both laboratories using the same sets of prepared filters from the inhalable sampling fraction of red oak, southern yellow pine, and western red cedar in the range of 0.125-4mg of wood dust. Using the same procedure in both laboratories to build the calibration curve and analyze the field samples, 62.3% of the samples measured within 25% of the average result with a mean difference between the laboratories of 18.5%. Some observations are included as to how the calibration and analysis can be improved. In particular, determining the wood type on each sample to allow matching to the most appropriate calibration increases the apparent proportion of wood dust in the sample and this likely provides more realistic DRIFTS results. |
Determination of airborne wood dust in Button samples by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS)
Kwon CW , Chirila M , Lee T , Harper M , Rando RJ . Int J Environ Anal Chem 2013 93 (13) 1356-66 Emerging concerns regarding the toxicity of inhaled wood dust support the need for techniques to quantitate wood content of mixed industrial dusts. The diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) analysis technique was applied to the determination of wood content of 181 inhalable dust samples (geometric mean concentration: 0.895mg/m(3); geometric standard deviation: 2.73) collected from six wood product industry factories using 25 mm glass fibre filters with the Button aerosol sampler. Prior to direct DRIFTS analysis the filter samples were treated with ethyl acetate and re-deposited uniformly. Standards ranging from 125 mcg to 4000 mcg were prepared for red oak, southern yellow pine, and red cedar and used for quantitation of samples depending upon the wood materials present at a given factory. The oak standards spectra were quantitated by linear regression of response in Kubelka-Munk units at 1736 cm(-1), whereas the pine standards and the cedar standards spectra were quantitated by polynomial regression of response in log 1/R units at 1734 cm(-1), with the selected wavenumbers corresponding to stretching vibration of free C=O from cellulose and hemicelluloses. For one factory which used both soft- and hard-woods, a separate polynomial standard curve was created by proportionally combining the oak and pine standards polynomial regression equations based on response (log 1/R) at 1734 cm(-1). The analytical limits of detection were approximately 52 mcg of oak, 20 mcg of pine, 30 mcg of cedar, and 16 mcg of mixed oak and pine for the factory with mixed woods. Overall, the average of dry wood dust percentage of inhalable dust was approximately 56% and the average dry wood dust weight was 0.572 mg for the Button samples. Across factories, there were statistically significant differences (p<0.001) for the percentage of dry wood dust in inhalable dust with factory averages ranging from 33.5 to 97.6%. |
Quantitative mid-infrared diffuse reflection of occupational wood dust exposures
Chirila MM , Lee T , Flemmer MM , Slaven JE , Harper M . Appl Spectrosc 2011 65 (3) 243-9 Occupational exposure to airborne wood dust has been implicated in the development of several symptoms and diseases, including nasal carcinoma. However, the assessment of occupational wood dust exposure is usually performed by gravimetric analysis, which is non-specific. In this study, a mid-infrared (mid-IR) diffuse reflection method was adapted for direct on-filter determination of wood dust mass. The cup from the diffuse reflection unit was replaced with a horizontal translational stage and a filter with wood dust was set thereon. Diffuse reflection (DR) spectra were collected from filters with six different diameters in order to average the signal from the most filter surface. Two absorption bands around 1595 and 1510 cm(-1), attributed to lignin, were monitored for quantitative analysis. Calibration curves were constructed for standard extrathoracic red oak and yellow pine (aerodynamic particle diameters between 10 and 100 mum). Calibration of DR intensity versus known wood dust mass on the filter using the Kubelka-Munk function showed a nonlinear dependence for mass of less than 10 mg of wood dust. The experimental data and small-thickness samples indicate that Kubelka-Munk conditions are not obeyed. Alternatively, the pseudo-absorption function log(1/R), for which R is the relative reflectance, while still giving nonlinear dependence against mass, is closer to a linear dependence and has been preferred by other researchers. Therefore, we consider the use of the log(1/R) function for mid-infrared DR analysis of neat, small-thickness wood dust samples. Furthermore, we suggest the use of a silver metal membrane filter for direct on-filter analysis of wood dust rather than the glass fiber filters that have been used previously. |
Genotoxicity of carbon nanofibers: are they potentially more or less dangerous than carbon nanotubes or asbestos?
Kisin ER , Murray AR , Sargent L , Lowry D , Chirila M , Siegrist KJ , Schwegler-Berry D , Leonard S , Castranova V , Fadeel B , Kagan VE , Shvedova AA . Toxicol Appl Pharmacol 2011 252 (1) 1-10 The production of carbon nanofibers and nanotubes (CNF/CNT) and their composite products is increasing globally. CNF are generating great interest in industrial sectors such as energy production and electronics, where alternative materials may have limited performance or are produced at a much higher cost. However, despite the increasing industrial use of carbon nanofibers, information on their potential adverse health effects is limited. In the current study, we examine the cytotoxic and genotoxic potential of carbon-based nanofibers (Pyrograf ((R))-III) and compare this material with the effects of asbestos fibers (crocidolite) or single-walled carbon nanotubes (SWCNT). The genotoxic effects in the lung fibroblast (V79) cell line were examined using two complementary assays: the comet assay and micronucleus (MN) test. In addition, we utilized fluorescence in situ hybridization to detect the chromatin pan-centromeric signals within the MN indicating their origin by aneugenic (chromosomal malsegregation) or clastogenic (chromosome breakage) mechanisms. Cytotoxicity tests revealed a concentration- and time-dependent loss of V79 cell viability after exposure to all tested materials in the following sequence: asbestos>CNF>SWCNT. Additionally, cellular uptake and generation of oxygen radicals was seen in the murine RAW264.7 macrophages following exposure to CNF or asbestos but not after administration of SWCNT. DNA damage and MN induction were found after exposure to all tested materials with the strongest effect seen for CNF. Finally, we demonstrated that CNF induced predominately centromere-positive MN in primary human small airway epithelial cells (SAEC) indicating aneugenic events. Further investigations are warranted to elucidate the possible mechanisms involved in CNF-induced genotoxicity. |
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