The Experts below are selected from a list of 300 Experts worldwide ranked by ideXlab platform
Kyle J. Hazelwood - One of the best experts on this subject based on the ideXlab platform.
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Exposure-related health effects of silver and silver compounds: A review
Annals of Occupational Hygiene, 2005Co-Authors: P. L. Drake, Kyle J. HazelwoodAbstract:A critical review of studies examining Exposures to the various forms of silver was conducted to determine if some silver species are more toxic than others. The impetus behind conducting this review is that several occupational Exposure Limits and guidelines exist for silver, but the values for each depend on the form of silver as well as the individual agency making the recommendations. For instance, the American Conference of Governmental Industrial Hygienists has established separate threshold Limit values for metallic silver (0.1 mg/m3) and soluble compounds of silver (0.01 mg/m3). On the other hand, the Permissible Exposure Limit (PEL) recommended by the Occupational Safety and Health Administration and the Mine Safety and Health Administration and the recommended Exposure Limit set by the National Institute for Occupational Safety and Health is 0.01 mg/m3 for all forms of silver. The adverse effects of chronic Exposure to silver are a permanent bluish-gray discoloration of the skin (argyria) or eyes (argyrosis). Most studies discuss cases of argyria and argyrosis that have resulted primarily from Exposure to the soluble forms of silver. Besides argyria and argyrosis, Exposure to soluble silver compounds may produce other toxic effects, including liver and kidney damage, irritation of the eyes, skin, respiratory, and intestinal tract, and changes in blood cells. Metallic silver appears to pose minimal risk to health. The current occupational Exposure Limits do not reflect the apparent difference in toxicities between soluble and metallic silver; thus, many researchers have recommended that separate PELs be established.
P. L. Drake - One of the best experts on this subject based on the ideXlab platform.
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Exposure-related health effects of silver and silver compounds: A review
Annals of Occupational Hygiene, 2005Co-Authors: P. L. Drake, Kyle J. HazelwoodAbstract:A critical review of studies examining Exposures to the various forms of silver was conducted to determine if some silver species are more toxic than others. The impetus behind conducting this review is that several occupational Exposure Limits and guidelines exist for silver, but the values for each depend on the form of silver as well as the individual agency making the recommendations. For instance, the American Conference of Governmental Industrial Hygienists has established separate threshold Limit values for metallic silver (0.1 mg/m3) and soluble compounds of silver (0.01 mg/m3). On the other hand, the Permissible Exposure Limit (PEL) recommended by the Occupational Safety and Health Administration and the Mine Safety and Health Administration and the recommended Exposure Limit set by the National Institute for Occupational Safety and Health is 0.01 mg/m3 for all forms of silver. The adverse effects of chronic Exposure to silver are a permanent bluish-gray discoloration of the skin (argyria) or eyes (argyrosis). Most studies discuss cases of argyria and argyrosis that have resulted primarily from Exposure to the soluble forms of silver. Besides argyria and argyrosis, Exposure to soluble silver compounds may produce other toxic effects, including liver and kidney damage, irritation of the eyes, skin, respiratory, and intestinal tract, and changes in blood cells. Metallic silver appears to pose minimal risk to health. The current occupational Exposure Limits do not reflect the apparent difference in toxicities between soluble and metallic silver; thus, many researchers have recommended that separate PELs be established.
Mark L Witten - One of the best experts on this subject based on the ideXlab platform.
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pulmonary evaluation of Permissible Exposure Limit of syntroleum s 8 synthetic jet fuel in mice
Toxicological Sciences, 2009Co-Authors: Simon S Wong, Alana Thomas, Brian Barbaris, Clark R Lantz, Mark L WittenAbstract:No current studies have systematically examined pulmonary health effects associated with Syntroleum S-8 synthetic jet fuel (S-8). In order to gain an understanding about the threshold concentration in which lung injury is observed, C57BL/6 male mice were nose-only exposed to S-8 for 1 h/day for 7 days at average concentrations of 0 (control), 93, 352, and 616 mg/m3. Evaluation of pulmonary function, airway epithelial barrier integrity, and pathohistology was performed 24 h after the final Exposures. Significant decreases were detected in expiratory lung resistance and total lung compliance of the 352 mg/m3 group, for which no clear concentration-dependent alterations could be determined. No significant changes in respiratory permeability were exhibited, indicating that there was no loss of epithelial barrier integrity following S-8 Exposure. However, morphological examination and morphometric analysis of distal lung tissue, by using transmission electron microscopy, revealed cellular damage in alveolar type II epithelial cells, with significant increases in volume density of lamellar bodies/vacuoles at 352 and 616 S-8 mg/m3. Moreover, terminal bronchiolar Clara injury, as evidenced by apical membrane blebs, was observed at relatively low concentrations, suggesting if this synthetic jet fuel is utilized, the current Permissible Exposure Limit of 350 mg/m3 for hydrocarbon fuels should cautiously be applied.
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in vivo comparison of epithelial responses for s 8 versus jp 8 jet fuels below Permissible Exposure Limit
Toxicology, 2008Co-Authors: Simon S Wong, Alana Thomas, Clark R Lantz, Jason E Vargas, Cindy Fastje, Michael Mclaughlin, Ryan Camponovo, Jeffrey J Heys, Mark L WittenAbstract:Abstract This study was designed to characterize and compare the pulmonary effects in distal lung from a low-level Exposure to jet propellant-8 fuel (JP-8) and a new synthetic-8 fuel (S-8). It is hypothesized that both fuels have different airway epithelial deposition and responses. Consequently, male C57BL/6 mice were nose-only exposed to S-8 and JP-8 at average concentrations of 53 mg/m 3 for 1 h/day for 7 days. A pulmonary function test performed 24 h after the final Exposure indicated that there was a significant increase in expiratory lung resistance in the S-8 mice, whereas JP-8 mice had significant increases in both inspiratory and expiratory lung resistance compared to control values. Neither significant S-8 nor JP-8 respiratory permeability changes were observed compared to controls, suggesting no loss of epithelial barrier integrity. Morphological examination and morphometric analysis of airway tissue demonstrated that both fuels showed different patterns of targeted epithelial cells: bronchioles in S-8 and alveoli/terminal bronchioles in JP-8. Collectively, our data suggest that both fuels may have partially different deposition patterns, which may possibly contribute to specific different adverse effects in lung ventilatory function.
Raymond D Harbison - One of the best experts on this subject based on the ideXlab platform.
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airborne asbestos concentration from brake changing does not exceed Permissible Exposure Limit
Regulatory Toxicology and Pharmacology, 2003Co-Authors: Charles L Blake, Drew Van Orden, Marek Banasik, Raymond D HarbisonAbstract:Abstract The use in the past, and to a lesser extent today, of chrysotile asbestos in automobile brake systems causes health concerns among professional mechanics. Therefore, we conducted four separate tests in order to evaluate an auto mechanic’s Exposure to airborne asbestos fibers while performing routine brake maintenance. Four nearly identical automobiles from 1960s having four wheel drum brakes were used. Each automobile was fitted with new replacement asbestos-containing brake shoes and then driven over a predetermined public road course for about 2253 km. Then, each car was separately brought into a repair facility; the brakes removed and replaced with new asbestos-containing shoes. The test conditions, methods, and tools were as commonly used during the 1960s. The mechanic was experienced in brake maintenance, having worked in the automobile repair profession beginning in the 1960s. Effects of three independent variables, e.g., filing, sanding, and arc grinding of the replacement brake shoe elements, were tested. Personal and area air samples were collected and analyzed for the presence of fibers, asbestos fibers, total dust, and respirable dust. The results indicated a presence in the air of only chrysotile asbestos and an absence of other types of asbestos. Airborne chrysotile fiber Exposures for each test remained below currently applicable Limit of 0.1 fiber/ml (eight-hour time-weighted average).
Boris Mizaikoff - One of the best experts on this subject based on the ideXlab platform.
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Monitoring of hydrogen sulfide via substrate-integrated hollow waveguide mid-infrared sensors in real-time
Analyst, 2014Co-Authors: João Flávio Da Silveira Petruci, Paula Regina Fortes, Vjekoslav Kokoric, Andreas Wilk, Ivo Milton Raimundo, Arnaldo Alves Cardoso, Boris MizaikoffAbstract:Hydrogen sulfide is a highly corrosive, harmful, and toxic gas produced under anaerobic conditions within industrial processes or in natural environments, and plays an important role in the sulfur cycle. According to the U.S. Occupational Safety and Health Administration (OSHA), the Permissible Exposure Limit (during 8 hours) is 10 ppm. Concentrations of 20 ppm are the threshold for critical health issues. In workplace environments with human subjects frequently exposed to H2S, e.g., during petroleum extraction and refining, real-time monitoring of Exposure levels is mandatory. Sensors based on electrochemical measurement principles, semiconducting metal-oxides, taking advantage of their optical properties, have been described for H2S monitoring. However, extended response times, Limited selectivity, and bulkiness of the instrumentation are common disadvantages of the sensing techniques reported to date. Here, we describe for the first time usage of a new generation of compact gas cells, i.e., so-called substrate-integrated hollow waveguides (iHWGs), combined with a compact Fourier transform infrared (FTIR) spectrometer for advanced gas sensing of H2S. The principle of detection is based on the immediate UV-assisted conversion of the rather weak IR-absorber H2S into much more pronounced and distinctively responding SO2. A calibration was established in the range of 10-100 ppm with a Limit of detection (LOD) at 3 ppm, which is suitable for occupational health monitoring purposes. The developed sensing scheme provides an analytical response time of less than 60 seconds. Considering the substantial potential for miniaturization using e.g., a dedicated quantum cascade laser (QCL) in lieu of the FTIR spectrometer, the developed sensing approach may be evolved into a hand-held instrument, which may be tailored to a variety of applications ranging from environmental monitoring to workplace safety surveillance, process analysis and clinical diagnostics, e.g., breath analysis.