Screening check test to confirm the relative reactivity and applicability of 2,4-dinitrophenylhydrazine impregnated-filters for formaldehyde on other compounds.

OBJECTIVES: A simple check test method was designed to confirm whether a 2,4-dinitrophenylhydrazine (DNPH) filter for formaldehyde can be used to measure other compounds. METHODS: Sample mixtures containing the same concentrations of formaldehyde, acetaldehyde, and acetone were spiked to the DNPH-filter, extracted, and then measured using high performance liquid chromatography with photodiode array detector (HPLC-PDA). The amounts of DNPH-derivatives versus the amounts of spiked samples were then plotted. RESULTS: When the amount of DNPH << the total amount of spiked samples, the amount of DNPH-derivatives was formaldehyde > acetaldehyde >> acetone. This order corresponded to the relative rate constants for the reaction. Therefore, this study confirmed that acetone was not collected at the formaldehyde sampling rate. CONCLUSIONS: This check test easily measured the reaction rate order and can be used as a simple test to determine whether other samples can be measured by the analytical methods used for the specified sample.

Analytical method using SEM-EDS for metal elements present in particulate matter generated from stainless steel flux-cored arc welding process.

Welding fumes (WFs) can cause occupational pneumonoconiosis and other diseases in workers. WFs have complex chemical composition and morphology depending on the welding conditions. The WF surface is a key factor affecting those diseases. The objective of this study was to establish an analytical method focused on characterizing individual WFs and welding slags (WSs) formed during CO2 arc welding processes for knowledge acquisition of risk assessment. Especially, the characterization was focused on the elemental distributions near the surfaces obtained using fluxing agents and size of the WFs. WFs were collected using personal samplers. After welding, WS was also collected. The fluxing elemental distribution (e.g., Bi) near the surfaces WS and WFs were analyzed through scanning electron microscopy and energy-dispersive X-ray spectroscopy. As a result, some of the micron-sized spherical particles (SPs) grew by incorporating nanosized primary particles composed of other metal species. The fluxing agents formed elemental distribution patterns on the SP surface. Bi were dotted in an agglomerate. Mn amount in WS depends on Mn amount in the WFs. These results obtained through the analysis of both the WS and WF surface as well as the particle sizes will facilitate the establishment of exposure assessment models.

Exposure assessment of nanotitanium oxide powder handling using real-time size-selective particle number concentration measurements and X-ray fluorescence spectrometry -The possibility of exposure to nonagglomerated nanomaterials during the handling of nanomaterial fine powders.

In this study, airborne particles were collected using filters, and the particle number concentrations were measured in two nanotitanium dioxide (nanoTiO2)-manufacturing plants. Real-time particle size measurements were performed using both optical and scanning mobility particle sizer and X-ray fluorescence spectrometry (XRF). The respirable particles collected using filters were used to analyze Ti concentrations in the workplace air of two factories engaged in nanoTiO2 powder bagging processes. The XRF analysis revealed sufficient sensitivity to measure 0.03 mg/m3, which is 1/10 the concentration of the recommended occupational exposure limit of nanoTiO2 in both stationary sampling and personal exposure sampling settings. In a factory where outside air was directly introduced, micron-sized aggregated particles were generated because of factory operations; however, nanosized and submicron-sized particles were not observed owing to high background concentrations of incidental nanoparticles. Alternatively, in another factory where particles from the outside air were removed using a high-efficiency particulate air filter, work-related nanoparticles were released. The findings of this study suggest that in nanoparticle powder handling processes, a nanoparticle exposure risk exists in the form of nonagglomerated state in nanoparticle powder handling processes.

Examination of validity of a conditioned odor aversion (COA) procedure using low-dose of organic solvent as an applied procedure of the conditioned taste aversion.

Smell of very low dose of chemical might evoke subjective physical symptoms in human by some process of learning named the aversion conditioning. But few scientific evidences of the hypothesis have been reported so far. Validity of conditioned odor aversion (COA) using low-doses of organic solvent as odor conditioned stimulus (CS) was examined. In conditioning phase, water-deprived male Sprague-Dawley rats were presented low, medium or high dose solution for 30 min followed by 0.3 M Lithium Chloride (LiCl) solution or saline injection. The xylene solution and drink water were simultaneously provided on the next day as two-bottle test. Consumption of medium dose of xylene solution was significantly decreased in LiCl injection group as compared with saline group. There was no difference between LiCl and saline injected animals in low group. Animals in high dose did not access to xylene even on the conditioning. These results indicate that animals showed high sensitivity for discrimination against concentration of xylene and that the medium dose of xylene functioned as the CS. We concluded that the COA used in the present study may be one of useful procedures to investigate olfaction of animal.

Performance evaluation of newly developed portable aerosol sizers used for nanomaterial aerosol measurements.

Nanomaterial particles exhibit a wide range of sizes through the formation of agglomerates/aggregates. To assess nanomaterial exposure in the workplace, accurate measurements of particle concentration and size distribution are needed. In this study, we evaluated the performance of two recently commercialized instruments: a portable scanning mobility particle sizer (SMPS) (NanoScan, TSI Inc.), which measures particle size distribution between 10 and 420 nm and an optical particle sizer (OPS, TSI Inc.), which measures particle size distribution between 300 and 10,000 nm. We compared the data measured by these instruments to conventional instruments (i.e., a widely used laboratory SMPS and an optical particle counter (OPC)) using nano-TiO(2) powder as test aerosol particles. The results showed obvious differences in the size distributions between the new and old SMPSs. A possible reason for the differences is that the cyclone inlet of the new SMPS (NanoScan) acted as a disperser of the weakly agglomerated particles and consequently the concentration increased through the breakup of the agglomerates. On the other hand, the particle concentration and size distributions measured by the OPS were similar to the OPC. When indoor aerosol particles were measured, the size distribution measured by the NanoScan was similar to the laboratory SMPS.

Evaluation of exposure risk in the weaving process of MWCNT-coated yarn with real-time particle concentration measurements and characterization of dust particles.

Various applications of multiwalled carbon nanotubes (MWCNT) have been developed. One of these applications is an efficient sheet heating element that is woven from MWCNT-coated yarn. In this research, we assessed the exposure to MWCNT and/or the probability of particle release from broken MWCNT-coated yarn during the weaving process. This was accomplished using particle concentrations, microscopic observation, and carbon analysis. In the weaving process, neither an increase in the number of particles nor a difference in particle-size distribution was observed. In the scanning electron micrographic observation, nanosize MWCNT particles were not detected, but there were micron-size particles containing MWCNT as fragments of the yarn. Carbon analysis showed the concentration of micron-size particles containing MWCNT did not exceed 0.0053 mg-C/m(3) around the loom. This value was much lower than the respirable dust mass concentration. Most of micron-size particles seemed to originate from polyester yarn without MWCNT coating. It is recommended that workers use conventional (even not specialized for nanoparticles) personal protective equipment such as respirators and gloves to prevent exposure to respirable-size MWCNT-containing particles. The probability of MWCNT fall-off from the MWCNT-coated yarn was not detected by transmission electron microscopic observation of MWCNT-coated yarn before or after the weaving process.

Translocation of intratracheally instilled multiwall carbon nanotubes to lung-associated lymph nodes in rats.

In order to assess the extrapulmonary effects of multiwall carbon nanotubes (MWCNT), deposition of MWCNT and histopathologic changes in lung-associated lymph nodes (LALN) were examined in MWCNT-administered rats. At the age of 13 wk, male F344 rats were intratracheally instilled with MWCNT at a dose of 0 (vehicle), 40 or 160 µg/rat. The rats were sacrificed on Day 1, 7, 28 or 91 after instillation and light microscopic examinations were performed on LALN tissues. MWCNT was translocated to right and left posterior mediastinal lymph nodes and parathymic lymph nodes. Deposition of MWCNT was greater in the posterior mediastinal lymph node than in the parathymic lymph node, and the amount of MWCNT deposited in these two lymph nodes increased gradually and dose-dependently with time. MWCNT was phagocytosed by nodal macrophages, and some of the MWCNT-laden macrophages were aggregated. Transmission electron microscopic (TEM) observation confirmed the presence of MWCNT fibers with a characteristic multi-walled cylindrical structure.

Characteristics of multiwall carbon nanotubes for an intratracheal instillation study with rats.

Much concern has been raised over the health consequences of workers exposed to carbon nanotubes. In order to characterize multi-wall carbon nanotubes (MWCNT) suspended in a phosphate-buffered saline containing 0.1% Tween 80 for an intratracheal instillation study. Length and width distributions of the MWCNT fibers, dispersion of MWCNT in the suspension and in the lung tissue and the MWCNT contents of metal impurities were investigated. Arithmetic mean length and width of the MWCNT fibers as measured on scanning electron microscope (SEM) photographs were 5.0 microm and 88 nm, respectively, and fibers longer than 5.0 microm were 38.9% of all fibers measured. Dynamic light scattering size measurement revealed that 5-min ultrasonication, together with addition of Tween 80 into the suspension, decreased the hydrodynamic diameters of the agglomerated MWCNT to those of finer particles below 1.0 microm. SEM observation showed good dispersion of MWCNT in the suspension, and in the alveoli on Day 1 after instillation. Concentration of iron, chromium and nickel in the MWCNT were 4,400, 48 and 17 ppm (wt/wt), respectively, all of which were below levels that would elicit positive pulmonary toxic responses to these metals. The results suggest that well-dispersed, long and thin MWCNT fibers exhibit asbestos-like pathogenicity in the lung.

Pulmonary toxicity of intratracheally instilled multiwall carbon nanotubes in male Fischer 344 rats.

In order to assess pulmonary toxicity of multiwall carbon nanotubes (MWCNT), male F344 rats were intratracheally instilled with MWCNT suspension at a dose of 40 or 160 µg/head or α-quartz particles as a positive control at a dose of 160 µg/head and sacrificed for lung histopathology and bronchoalveolar lavage (BAL) fluid analyses on Day 1, 7, 28 or 91 after instillation. Well-dispersed MWCNT brought about dose- or time-dependent changes in lung weight, total proteins, albumin, lactate dehydrogenase and alkaline phosphatase in the BAL fluid, and pulmonary lesions including inflammation, Type II cell hyperplasia, microgranulomas and fibrosis. Phagocytosed and free forms of MWCNT were found in both bronchiolar and alveolar spaces. MWCNT deposition in the bronchus-associated lymphoid tissue gradually increased after instillation. Persistent infiltration of macrophages, transient infiltration of inflammatory cells primarily composed of neutrophils, microgranulomas associated with macrophages engulfing MWCNT, Type II cell hyperplasia and fibrosis with alveolar wall thickening as well as number of multinucleated alveolar macrophages increased dose-dependently. The MWCNT-induced lesions were more potent on Day 91 than the α-quartz-induced ones at an equal mass dose. The present results for intratracheally instilled MWCNT were extrapolated to potential inhalation exposure of humans to MWCNT at workplaces based on several assumptions.

[Airborne particles in a multi-wall carbon nanotube production plant: observation of particle emission and personal exposure 1: Measurement in the packing process].

OBJECTIVES: In order to assess the exposure risks of multiwall carbon nanotubes (MWCNT) for packing workers, we carried out real-time monitoring in the two types of packing facilities of MWCNT, and exposure measurements for the packing workers. METHODS: In the real-time monitoring, a scanning mobility particle sizer (SMPS) and an optical particle counter (OPC) were used to measure nanoscale particles and sub-micron/micron scale particles, respectively. A personal sampler with PM 4.0 was used to measure the personal exposures in the packing facilities. RESULTS: One of the packing facilities is manually operated and the other is automated. The concentrations of airborne dust in both facilities were almost the same as each other at 0.24 mg/m(3) (total dust). However, the results of personal exposure measurements were quite different between the two facilities. The exposure concentrations of workers in the manually and automated operations were 2.39/0.39 (total/respirable) mg/m(3) and 0.29/0.08 (total/respirable) mg/m(3), respectively. From the time series study, submicron scale particles were released into the workplace air when the CNT products were put into temporary container bags from a hopper and manually packed into shipping bags. However, the task-related nanoscale particle release was not observed. CONCLUSIONS: The manual packing operation is one of the "hot spots" in MWCNT production facilities, and automation brings much improvement to reduce MWCNT exposure.

Genotoxicity and cytotoxicity of multi-wall carbon nanotubes in cultured Chinese hamster lung cells in comparison with chrysotile A fibers.

OBJECTIVES: The potential applications and industrial production of multi-wall carbon nanotubes (MWCNT) have raised serious concerns about their safety for human health and the environment. The present study was designed to examine the in vitro cytotoxicity and genotoxicity of MWCNT and UICC chrysotile A (chrysotile). METHODS: Cytotoxicity using both colony formation and lactate dehydrogenase (LDH) assays and genotoxicity including chromosome aberration, micronucleus induction and hgprt mutagenicity were examined by exposing cultured Chinese hamster lung (CHL/IU) cells to MWCNT or chrysotile at different concentrations. RESULTS: The in vitro cytotoxicity of MWCNT depended on the solvent used for suspension of MWCNT and ultrasonication duration of the MWCNT suspension. A combination of DMSO/culture medium and 3-minute ultrasonication resulted in a well-dispersed medium with dispersion and isolation of agglomerated MWCNT by ultrasonication which manifested the highest cytotoxicity. The cytotoxicity was more potent for chrysotile than MWCNT. The genotoxicity of MWCNT was characterized by the formation of polyploidy without structural chromosome aberration, and an increased number of bi- and multi-nucleated cells without micronucleus induction, as well as negative hgprt mutagenicity. Chrysotile exhibited essentially the same genotoxicity as MWCNT, except for marginal but significant induction of micronuclei. MWCNT and chrysotile were incompletely internalized in the cells and localized in the cytoplasm. CONCLUSIONS: MWCNT and chrysotile were cytotoxic and genotoxic in Chinese hamster lung cells, but might interact indirectly with DNA. The results suggest that both test substances interfere physically with biological processes during cytokinesis.

Pulmonary toxicity induced by intratracheal instillation of coarse and fine particles of cerium dioxide in male rats.

In order to examine the short-, medium- and long-term effects of cerium dioxide particles of different sizes on the lung, 10-wk-old male Wistar rats were administered a physiological saline solution with a suspension of coarse or fine particles of cerium dioxide at 34 mg/kg body weight by a single intratracheal instillation. Lungs were examined with cellular and biochemical analyses of the bronchoalveolar lavage (BAL) fluid and histopathology on different days after the instillation. Geometric mean and geometric standard deviation of the diameter were 3.90 microm +/- 1.93 for the coarse (Ce-C) particles, and 0.20 microm +/- 1.20 for the fine (Ce-F) particles. There were no lesions in the lung in the Ce-C-instilled group at any time point after the instillation. The instillation of Ce-F particles primarily induced inflammation, granulomas, mobilization and impairment of alveolar macrophages (AMs), and pulmonary alveolar proteinosis, together with very slight degrees of Type II epithelial cell hyperplasia and of collagen deposition. The pulmonary toxicity of Ce-F-instilled rats was found to be markedly enhanced in sharp contrast to that of Ce-C-instilled rats on the basis of equal mass concentration, suggesting clear dependence of the pulmonary toxicity on numbers and sizes of particles. Causative factors for the pulmonary alveolar proteinosis are discussed with reference to the impaired AMs.

Dissolution of functional materials and rare earth oxides into pseudo alveolar fluid.

The dissolution rates of rare earth oxides and two types of rare earth containing functional materials into water, saline solution, and Gamble's fluid were measured in order to evaluate the biological effects of rare earth-containing functional materials. The tested materials were yttrium, lanthanum, cerium and neodymium oxides, and neodymium-boron-iron magnet alloy (NdBFe) and lanthanum-mish-metal-nickel-cobalt (LmNiCo) hydrogen-containing alloy. The dissolution rates of the rare earth oxides were very low, resulting in concentrations of rare earth elements in the test solutions of the order of ppb. In the most extreme case, Gamble's fluid dissolved 1,400 times more of the rare earth oxides than pure water. Fairly high concentration of neodymium were found in the dissolving fluids, which means that trace neodymium present as an impurity in each rare earth oxide dissolved preferentially. For yttrium oxide, the ratio of neodymium to yttrium that dissolved in the saline solution was greater than 78,000 to 1, taking into account the amount of each that was originally present in the yttrium oxide.

Field evaluation of mercury vapor analytical methods: comparison of the "double amalgam method" and ISO 17733.

In this study, a gold amalgam method called the "Double amalgam method" was compared with the ISO 17733 method for mercury vapor analysis method. In terms of sensitivity and ease of operation, the amalgamation method is superior to the oxidation method. Two parallel samplings were carried out in this research at a button battery factory, where the mercury vapor level in the air was about 0.001 mg/m3 and at a fluorescent lamp factory, where the mercury vapor level was about 0.015 mg/m3. In the both cases, the measured values of the two showed good agreement with each other. As these two workplaces represent typical mercury levels in industries today, the double amalgam method is applicable to working environment measurement.