• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.28 no.2
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• pp.135-143
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• 2018

Objectives: There have been many studies on exposure assessment of workers at companies using asbestos as a raw material and at sites of the removal of materials containing asbestos. However, no research has been carried out on the asbestos exposure of workers in industries involving asbestos-containing waste, such as workers at collection and transportation service companies, mid-treatment companies(solidification of asbestos-containing waste), and landfill sites. The objective of this study was to assess the asbestos exposure concentrations of workers in industries handling waste containing asbestos. Methods: For this study, we carried out field investigations at 15 companies: seven collection and transportation service companies, three mid-treatment companies, and five final treatment companies(landfill sites). We took both personal and area samples. Results: The range of asbestos exposure levels of workers handing asbestos-containing wastes at collection, mid-treatment, and landfill companies were 0.000 fibers/cc-0.009 fibers/cc, 0.000 fibers/cc-0.038 fibers/cc, and 0.000 fibers/cc-0.024 fibers/cc, respectively. Conclusions: The asbestos exposure levels of workers at mid-treatment companies were higher than those at collection and transportation companies and at final treatment companies. In the case of collection and transportation workers, the possibility of exposure to levels exceeding those found in the present study is not particularly high considering the characteristics of the work. However, in the case of intermediate or final disposal workers, it is considered that there is a possibility of exposure to levels above those found in this study.

• Environmental Analysis Health and Toxicology
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• v.29
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• pp.15.1-15.7
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• 2014

Objectives This paper tried to review a recent research trend for the environmental exposure of engineered nanomaterials (ENMs) and its removal efficiency in the nanowaste treatment plants. Methods The studies on the predicted environmental concentrations (PEC) of ENMs obtained by exposure modeling and treatment (or removal) efficiency in nanowaste treatment facilities, such as wastewater treatment plant (WTP) and waste incineration plant (WIP) were investigated. The studies on the landfill of nanowastes also were investigated. Results The Swiss Federal Laboratories for Materials Science and Technology group has led the way in developing methods for estimating ENM production and emissions. The PEC values are available for surface water, wastewater treatment plant effluents, biosolids, sediments, soils, and air. Based on the PEC modeling, the major routes for the environmental exposure of the ENMs were found as WTP effluents/sludge. The ENMs entered in the WTP were 90-99% removed and accumulated in the activated sludge and sludge cake. Additionally, the waste ash released from the WIP contain ENMs. Ultimately, landfills are the likely final destination of the disposed sludge or discarded ENMs products. Conclusions Although the removal efficiency of the ENMs using nanowaste treatment facilities is acceptable, the ENMs were accumulated on the sludge and then finally moved to the landfill. Therefore, the monitoring for the ENMs in the environment where the WTP effluent is discharged or biomass disposed is required to increase our knowledge on the fate and transport of the ENMs and to prevent the unintentional exposure (release) in the environment.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.20 no.3
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• pp.349-356
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• 2022

Nuclear power plant decommissioning generates significant concrete waste, which is slightly contaminated, and expected to be classified as clearance concrete waste. Clearance concrete waste is generally crushed into rubble at the site or a satellite treatment facility for practical disposal purposes. During the process, workers are exposed to radiation from the nuclides in concrete waste. The treatment processes consist of concrete cutting/crushing, transportation, and loading/unloading. Workers' radiation exposure during the process was systematically studied. A shielding package comprising a cylindrical and hexahedron structure was considered to reduce workers' radiation exposure, and improved the treatment process's efficiency. The shielding package's effect on workers' radiation exposure during the cutting and crushing process was also studied. The calculated annual radiation exposure of concrete treatment workers was below 1 mSv, which is the annual radiation exposure limit for members of the public. It was also found that workers involved in cutting and crushing were exposed the most.

• Anxiety and mood
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• v.12 no.2
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• pp.69-78
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• 2016

Objective : Disaster causes psychological distress to a large number of people in a short period of time, by both direct and indirect exposure to traumatic events embedded in various realms of disaster experience. Optimal, well-planned treatment interventions should follow from the early acute period to recovery phase, extending up to several months later. In this context, there is an increasing need for systemic review to gain comprehensive insights for disaster interventions. These need to be added to public policy, and for the prevention and treatment of disaster-related psychopathology. Here, we review the published studies on psychological interventions for disaster-related posttraumatic stress disorder. Methods : Specific psychological interventions regarded as effective treatments for have been selected for this review, such as CBT (Cognitive-Behavior Therapy), Exposure Therapy, EMDR (Eye Movement Desensitization & Reprocessing), SIT (Stress Inoculation Therapy) and Psychoeducation. In addition, natural disasters, industrial disasters, and accidents involving aircraft and ships were also categorized as disasters, along with war and combat trauma. Results : Cognitive behavior therapy and exposure therapy had the strongest research support for effectiveness, and could be considered as the first-choice treatment for disaster-related PTSD. The second line of treatment is EMDR, although this treatment modality has the advantage of reaching certain treatment improvements in fewer sessions. However, the effects of SIT and psychoeducation to the survivors of disasters, remains unclear at this point. Additionally, we propose the possibilities of using virtual reality component and imagery rescripting as modified forms of traditional cognitive behavior therapy and exposure therapy. Conclusion : Cognitive behavior therapy and exposure therapy, deemed effective treatments for various trauma, are considered to be effective for survivors from disasters. However, the efficacy of other interventions has not yet been examined methodologically in well-designed studies, such as randomized controlled trials. In particular, future empirical studies are needed, since it is difficult to conclude that psychological interventions have similar effects on different types of disasters.

• Korean Journal of Materials Research
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• v.11 no.11
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• pp.915-922
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• 2001

Effects of thermal exposure and rejuvenation treatment on the microstructural evolution and the stress-rupture properties of IN738LC have been investigated. The role of precipitates on the stress-rupture properties has been analyzed through microstructural observations. Thermal exposure at $982^{\circ}C$ for 1000 hours gave rise to precipitation of $\sigma$ phase and coarsening of r'. The microstructural degradation with thermal exposure at $982^{\circ}C$ deteriorated stress rupture properties of the alloy. All the existing phases except MC carbides have completely dissolved into the matrix with homogenization treatment at $1200^{\circ}C$ for 2 hours. Microstructure and stress-rupture properties of the thermal exposed specimens have been successfully rejuvenated by the proposed treatment.

• Korean Journal of Materials Research
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• v.11 no.10
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• pp.833-840
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• 2001

Effects of thermal exposure and rejuvenation treatment on the microstructural evolution and the stress-rupture properties of IN738LC have been investigated. The role of precipitates on the stress- rupture properties has been analyzed through microstructural observations. Thermal exposure at $982^{\circ}C$ for 1000 hours gave rise to precipitation of $\sigma$ phase and coarsening of ${\gamma}$'. The microstructural degradation with thermal exposure at $982^{\circ}C$ deteriorated stress rupture properties of the alloy. All the existing phases except MC carbides have completely dissolved into the matrix with homogenization treatment at $1200^{\circ}C$ for 2 hours. Microstructure and stress-rupture properties of the thermal exposed specimens have been successfully rejuvenated by the proposed treatment.

• Tuberculosis and Respiratory Diseases
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• v.85 no.3
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• pp.237-248
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• 2022

Background: We evaluated the effect of particulate matter (PM) and cigarette smoke extract (CSE) on bronchial epithelial cell survival, as well as oxidative stress and autophagy levels. Moreover, we aimed to assess the effect of the antioxidant N-acetylcysteine (NAC) on the adverse effects of PM and CSE exposure. Methods: Normal human bronchial epithelial cells (BEAS-2B cells) were exposed to urban PM with or without CSE, after which cytotoxic effects, including oxidative stress and autophagy levels, were measured. After identifying the toxic effects of urban PM and CSE exposure, the effects of NAC treatment on cell damage were evaluated. Results: Urban PM significantly decreased cell viability in a concentration-dependent manner, which was further aggravated by simultaneous treatment with CSE. Notably, pretreatment with NAC at 10 mM for 1 hour reversed the cytotoxic effects of PM and CSE co-exposure. Treatment with 1, 5, and 10 mM NAC was shown to decrease reactive oxygen species levels induced by exposure to both PM and CSE. Additionally, the autophagy response assessed via LC3B expression was increased by PM and CSE exposure, and this also attenuated by NAC treatment. Conclusion: The toxic effects of PM and CSE co-exposure on human bronchial epithelial cells, including decreased cell viability and increased oxidative stress and autophagy levels, could be partly prevented by NAC treatment.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.26 no.2
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• pp.225-236
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• 2016

Objectives: Nanomaterials have been used in various fields. As use of nanoproducts is increasing, workers dealing with nanomaterials are also gradually increasing. Exposure assessments for nanomaterials have been carried out for protection of worker's health in workplace. Exposure studies were mainly focused on manufacturing processes, but these studies on after-treatment processes such as refinement, weighing, and packing were insufficient. So, we investigated exposure characteristics of particles during after-treatment processes of $Al_2O_3$ fibers and Ni powders. Methods: Mass-production of Ni powder process was carried out in enclosed capture-type canopy hood. In a developing stage, $Al_2O_3$ was handled with a local ventilation unit. Exposure characteristics of particles were investigated for $Al_2O_3$ fiber and Ni powder processes during the periods of 10:00 to 16:00, 20 May 2014 and 13:00 to 16:00, 21 May 2014, respectively. Three real-time aerosol instruments were utilized in exposure assessment. A scanning mobility particle sizer(SMPS, nanoscan, model 3910, TSI) and an optical particle counter(OPC, portable aerosol spectrometer, model 1.109, Grimm) were used to determine the particle size distribution in the size range of 10-420 nm and $0.25-32{\mu}m$, respectively. In addition, a nanoparticle aerosol monitor(NAM, model 9000, TSI) was used to measure lung-deposited nanoparticle surface area. Membrane filters(isopore membrane filter, pore size of 100 nm) were also used for air sampling for the FE-SEM(model S-5000H, Hitachi) analysis using a personal sampling pump(model GilAir Plus by 2.5 L/min, Gilian). Conclusions: For Ni powder after-treatment process, only 27% increase in particle concentration was found during the process. However, for $Al_2O_3$ fiber after-treatment process, significant exposure(1.56-3.34 times) was observed during the process.

• Journal of the Korean Society of Tobacco Science
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• v.20 no.1
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• pp.99-107
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• 1998

Numerous studies have demonstrated a negative association between cigarette smoking and Parkinson's disease. The present study was undertaken to investigate whether chronic exposure of mice to cigarette smoke a(footed the metabolism of 1-methyl-1113,6-tetrahydro-pyridine (MPTP) by cytochrome P4SO (P-450) or flavin-containing monooxygenase (FMO) in the hepatic microsomes of C57BL6/J mice. Adult male C57BL6/J mice were exposed to mainstream smoke generated from 15 cigarettes for 10 min a day and 5 day per week for 6 weeks. MPTP (10 mg/kg body weight) was administered to mice by subcutaneous injection for 6 consecutive days. Microsolnal P-450 content was increased by MPTP, smoke exposure, or both, but NADPH cytochrome P-450 reductase activity was rather decreased by the same treatments. The activities of benzo(a)pyrene hydroxylase, 7-ethoxycoumarin O-deethylase and ethoxyresorufin O-deethylase were significantly increased by the exposure of cigarette smoke, but were not or little affected by MPTP treatment. Benzphetamine N-demethylase activity was not affected either by MPTP treatment or by cigarette smoke exposure, but it was significantly increased by the combined MPTP treatment with cigarette smoke exposure, showing their synergic effect for the induction of the enzyme activity. Interestingly, in vitro studies of hepatic FMO and P-450 system both O-oxygenation and N-demethylation of MPTP were increased in the smoke-exposed or in the MPTP-treated mice. These results suggest that the enhancement in the N-demethylation as well as O-deethylation of P-450 system and in the N-oxygenation of FMO activity by cigarette smoke exposure in mouse liver may contribute to attenuating the neurotoxic effects of MPTP on the nigrostriatal dopaminergic neurons.

• Journal of Environmental Health Sciences
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• v.22 no.4
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• pp.91-101
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• 1996

Exposure indices are important tools which enable scientists to reliably predict and detect exposures to xenobiotics and resultant cell injury. Since the de novo synthesis of stress proteins can be detected early after exposure to some agents, analysis of toxicant-induced changes in gene expression, i.e. alterations in patterns of protein synthesis, may be useful to develop as biomarkers of exposure and toxicity. The acute and chronic effects of cadmium(Cd, $CdCl_2$ 20 mg/kg) on Wistar male rats were evaluated concerning cadmium contents, tissues enzyme activity, HSP expression. The results of the study were as follows: 1. Less cadmium was absorbed through the digestive tracts, but the ratio of contents in renal to hepatic cadmium was higher at 8 weeks after treatment. 2. ALT(alanine aminotransferase), AST(aspartate aminotransferase), glucose, BUN(blood urea nitrogen), creatinine, the key indices of the clinical changes in hepatic and renal function were significantly changed by the cadmium treatment after 1 week in liver, after 4 weeks in kidney. 3. Enhanced synthesis of 70 KDa relative molecular mass proteins were detected in 2 hours after cadmium exposure, with maximum activity occurring at 8~48 hours. Induction of $HSP_{70}$ was evident at proximal tubules and glomeruli in kidney. Testicular cells produced enough HSP to be detected normally. From the above results, it could be concluded that $HSP_{70}$ induction by the cadmium treatment was a rapid reaction to indicate the exposure of xenobiotics.