• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.19 no.1
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• pp.123-132
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• 2021

Radiological impact analyses were carried out for a near-surface radioactive waste repository at Gyeongju in South Korea. The RESRAD-ONSITE code was applied for the estimation of maximum exposure doses by considering various exposure pathways based on a land area of 2,500 ㎡ with a 0.15 m thick contamination zone. Typical influencing input parameters such as shield depth, shield materials' density, and shield erosion rate were examined for a sensitivity analysis. Then both residential farmer and industrial worker scenarios were used for the estimation of maximum exposure doses depending on exposure duration. The radiation dose evaluation results showed that 60Co, 137Cs, and 63Ni were major contributors to the total exposure dose compared with other radionuclides. Furthermore, the total exposure dose from ingestion (plant, meat, and milk) of the contaminated plants was more significant than those assessed for inhalation, with maximum values of 5.5×10-4 mSv·yr-1 for the plant ingestion. Thus the results of this study can be applied for determining near-surface radioactive waste repository conditions and providing quantitative analysis methods using RESRAD-ONSITE code for the safety assessment of disposing radioactive materials including decommissioning wastes to protect human health and the environment.

• Journal of Preventive Medicine and Public Health
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• v.32 no.1
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• pp.17-29
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• 1999

Objectives. This study was carried out to analyze the hearingthreshold levels and relating factors of 1,048 workers with noiseinduced hearing loss$(D_1)$. Methods. We analyzed the hearing-threshold levels and relating factors of 1,048 workers with noise-induced hearing loss$(D_1)$ examined by the summary reports of specific health examination results of industries and personal reports of specific health examination results reported by 58 specific health examination institutes and 8 secondary pneumoconiosis examination institutes in 1996. Results. Among 1,048 workers at 510 workplaces, male workers were 1,009 (96.3%) and female workers were 39 (3.7%). The mean ages of workers initially exposed to noise and at present were 28.7 and 47.2, respectively. The duration of total exposure was 16.5 years. Average hearing-threshold levels analyzed by three-divided classification of the study subjects were 43.7dB(Lt) and 42.6dB(Rt). Those analyzed by six-divided classification were 50.5dB(Lt) and 48.6d8(Rt). Among workers with noise-induced shearing loss$(D_1)$, 16.3% was unilateral hearing loss and 84.6% was classified to compensation case. 8.8%(Rt) and 10.2%(Lt) of them were suspected to be conductive hearing loss by differences of air-bone hearing-threshold levels. Hearing-threshold levels of workers in manufacturing industry were significantly increased during the short exposure compared with the levels in mining industry. Among manufacturing industries, hearing-threshold levels of workers in trailer and other transportation equipment manufacturing industry were significantly increased. Age and duration of total noise exposure were not significantly related to the average hearing-threshold levels analyzed by three-divided classification. Hearing-threshold levels of female workers were significantly increased during the short exposure compared with those of male workers. Hearing-threshold levels of workers at the high risk group, ages of 20s, 30s and total exposure duration of less than 10 years, were not significantly increased compared with those of the other groups. However, they were exposed at young ages. The 3 leading industries of workers at high risk group were trailer and other transportation equipment manufacturing, automobile manufacturing and assemble-metal manufacturing industries. Conclusions. This study was the first nationwide analysis of the hearing-threshold levels and relating factors of workers with noise. induced hearing loss$(D_1)$. We found the differences of the real number by the statistics of the department of labour and the expected number of worker' s compensations for occupationally-induced hearing loss estimated by this study. According to the results of this study, we should carefully examine the methods to narrow this difference.

• Journal of Bio-Environment Control
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• v.16 no.4
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• pp.352-357
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• 2007

We investigated effects of concentration and duration were investigated in order to promote efficiency of $CO_2$ enrichment in winter. The treatments were conducted with two levels of $CO_2$ concentration, namely 400 ppm, 700 ppm, two levels of duration, 3 h (9:00-12:00), 6 h (9:00-15:00), and control (nonenrichment $CO_2$). Fresh weight of leaves increased under longer exposure to $CO_2$ and higher $CO_2$ concentration. Fresh weight of stem and root increased under longer exposure to $CO_2$, but decreased under higher $CO_2$ concentration. Total dry weight increased under longer exposure to $CO_2$ and higher $CO_2$ concentration. Combination treatment of longer exposure to $CO_2$ and higher $CO_2$ concentration showed the largest decrease of Root : Shoot dry weight ratio. The $700ppm{\times}6h$ treatment showed higher fruit number and yield than control. The results suggested that the growth under longer exposure to 400 ppm $CO_2$ was better than that under higher $CO_2$ concentration.

• Korean Journal of Optics and Photonics
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• v.28 no.1
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• pp.16-21
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• 2017

A systematic understanding of the effects of high-intensity flash sources on the human eye is strongly needed, not only for proper use of the sources, but for human eye health. In this study, the exposure-limit distance (ELD), indicating the minimal safe distance in case of seeing by chance a high-intensity flash, is proposed. The optical procedures to determine the ELD of a high-intensity flash are clarified, and the dependence of ELD on its parameters such as luminous intensity, duration, and radius of a flash are thoroughly investigated. From this investigation it is obvious that, while being weakly dependent on duration, the ELD is nearly proportional to the luminous intensity and the radius of a flash. The proposed ELD as an intuitive safety-indicating parameter is more useful and intuitive than the other characteristic parameters of a high-intensity flash. The ELD is expected to be an essential parameter as a safety indicator, to characterize the performance of a high-intensity flash and to promote the safety of the human eye.

• Journal of Preventive Medicine and Public Health
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• v.47 no.1
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• pp.27-35
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• 2014

Exposure factors based on the Korean population are required for making appropriate risk assessment. It is expected that handbooks for exposure factors will be applied in many fields, as well as by health department risk assessors. The present article describes the development of an exposure factors handbook that specifically focuses on human activities in situations involving the possible risk of exposure to environmental contaminants. We define majour exposure factors that represent behavioral patterns for risk assessment, including time spent on routine activities, in different places, on using transportation, and engaged in activities related to water contact including swimming, bathing and washing. Duration of residence and employment are also defined. National survey data were used to identify recommended levels of exposure factors in terms of time spent on routine activities and period of residence and employment. An online survey was conducted with 2073 subjects who were selected using a stratified random sampling method in order to develop a list of exposure factors for the time spent in different places and in performing water-related activities. We provide the statistical distribution of the variables, and report reference levels of average exposure based on the reliable data in our exposure factors handbook.

• Journal of Radiation Industry
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• v.11 no.1
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• pp.47-54
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• 2017

Compared to other occupations, there is a greater risk of exposure to radiation due to the use of radioisotopes in nuclear medicine for diagnostic evaluations and therapy. To consider ways to reduce exposure dose for those in nuclear medicine involved in injection work and elution work among radiation workers as well as for sanitation workers and trainees among frequent workers an investigation into exposure dose and situational analysis from changes in yearly exposure dose evaluations, changes in work environment and changes in forms of inspection were conducted. Exposure dose measurements were taken by using EPD MK2 worn during working hours for one injection worker, one elution worker, two sanitation workers, and one trainee at a general hospital in the Seoul area for three days from July 18th to 20th 2016. Radiation from radioisotopes which are a part of nuclear medicine can significantly affect not only radiation workers who deal with radioisotopes directly but also frequency works as well. According to this study the annual dose limit for elution workers and injection workers were considered safe as the amount of exposure was not large enough to have a significant effect. The limits of this study consist in the duration of this study and the quantity of participants. Also there was a limitation of the measurement device involving accumulated exposure, where the EPD MK2 cannot check the changes in exposure according to a particular activity.

• Journal of Environmental Health Sciences
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• v.44 no.5
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• pp.460-467
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• 2018

Objectives: The objectives of this study are to estimate the inhalation exposure level of benzene for workers using Tier 1 exposure models ECETOC TRA (European Center for Ecotoxicology and Toxicology of Chemicals Target Risk Assessment) and Stoffenmanager, and to investigate their reliability for exposure assessment in K-REACH. Methods: Two exposure scenarios, 'manufacture of benzene' and 'use as solvents,' were developed for assessment of workers' exposure to benzene. The Process Category (PROC) for ECETOC TRA was collected from the European Chemical Agency (ECHA) registration dossier, and the Activity for Stoffenmanager was converted from PROC using translation of exposure models (TREXMO). The information related to exposure, such as working duration, Respiratory Protective Equipment (RPE), Local Exhaust Ventilation (LEV), and Risk Management Measure (RMM) were classified into high, medium, and low exposure conditions. The risk was determined by the ratio of the estimated exposure and occupational exposure limits of benzene. Results: Under high exposure conditions, the worker exposure level calculated from all PROCs and Activities exceeded the risk level, with the exception of PROC 1 and Activity 1. In the medium exposure condition, PROC 8a, 8b, and 9 and Activity 3, 7, and 8 all exceeded the risk, whereas in the low condition, all PROCs and Activities were determined to be safe. As a result, action corresponding with the low exposure condition is required to reduce the risk of exposure among workers in workplaces where benzene is manufactured or used as a solvent. In addition, the predicted exposure levels derived from the exposure models were lower than measured levels. The exposure levels estimated from Stoffenmanager were more conservative than those from ECETOC TRA. Conclusions: This study demonstrates the feasibility of exposure models for exposure assessment through the example of occupational inhalation exposure assessment for benzene. For more active utilization of exposure models in K-REACH, the exact application of collected information and accurate interpretation of obtained results are necessary.

• Journal of Environmental Health Sciences
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• v.44 no.2
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• pp.107-114
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• 2018

Objectives: The objectives of this study are to describe strategy for exposure assessment of humidifier disinfectant (HD) used in the national program to associate the use of HD with lung injury. Methods: Strategy and method employed to evaluate HD use characteristics were developed to associate health effects including HD associated with lung injury (HDLI). We developed HD-specific questionnaire to assess potential HD exposure, which was consistently used in the national program. Trained environmental health scientists visited the residences of registered subjects and investigated HD use characteristics. Results: Major HD exposure related variables were type of HD brand/s used; HD volume added to the humidifier, frequency of HD addition, and time spent in room/s with the humidifier; duration of HD use in the household in average months/year, weeks/month, and days/week; average sleeping hours in a room with an operating humidifier containing a disinfectant; number of HD brands used and type of HD; average distance of the bed from the humidifier in meters. Conclusions: We concluded that estimated airborne HD concentration was significantly associated with the risk of HDLI.

• Environmental Analysis Health and Toxicology
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• v.17 no.3
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• pp.197-205
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• 2002

Volatile organic compounds (VOCs) are an important public health problem throughout the world. Many important questions remain to be addressed in assessing exposure to these compounds. Because they are ubiquitous and highly volatile, special techniques must be applied in the analytical determination of VOCs. Personal exposure measurements are needed to evaluate the relationship between microenvironmental concentrations and actual exposures. It is also important to investigate exposure frequency, duration, and intensity, as well as personal exposure characteristics. In addition to air monitoring, biological monitoring may contribute significantly to risk assessment by allowing estimation of absorbed doses, rather than just the external exposure concentrations, which are evaluated by environmental and personal monitoring. This study was conducted to establish the analytic procedure of VOCs in air, blood, urine and exhaled breath and to evaluate the relationships among these environmental media. The subjects of this study were selected because they are occupationally exposed to high levels of VOCs. Environmental, personal, blood, urine and exhalation samples were collected. Purge ＆ trap, thermal desorber, gas chromatography and mass selective detector were used to analyze the collected samples. Analytical procedures were validated with the“break through test”, 'quot;recovery test for storage and transportation”,“method detection limit test”and“inter-laboratory QA/QC study”. Assessment of halogenated compounds indicted that they were significantly correlated to each other (p value < 0.01). In a similar manner, aromatic compounds were also correlated, except in urine sample. Linear regression was used to evaluate the relationships between personal exposures and environmental concentrations. These relationships for aromatic and halogenated are as follows: Halogen $s_{personal}$ = 3.875+0.068Halogen $s_{environmet}$, ($R^2$= .930) Aromatic $s_{personal}$ = 34217.757-31.266Aromatic $s_{environmet}$, ($R^2$= .821) Multiple regression was used to evaluate the relationship between exposures and various exposure deter-minants including, gender, duration of employment, and smoking history. The results of the regression model-ins for halogens in blood and aromatics in urine are as follows: Halogen $s_{blood}$ = 8.181+0.246Halogen $s_{personal}$+3.975Gender ($R^2$= .925), Aromatic $s_{urine}$ = 249.565+0.135Aromatic $s_{personal}$ -5.651 D.S ($R^2$ = .735), In conclusion, we have established analytic procedures for VOC measurement in biological and environmental samples and have presented data demonstrating relationships between VOCs levels in biological media and environmental samples. Abbreviation GC/MS, Gas Chromatography/Mass Spectrometer; VOCs, Volatile Organic Compounds; OVM, Organic Vapor Monitor; TO, Toxic Organicsapor Monitor; TO, Toxic Organics.

• Journal of Sericultural and Entomological Science
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• v.40 no.1
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• pp.23-26
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• 1998

Exposure of freshly laid eggs of Exorista bombycis (Louis) to volatiles emanating from bulbs of Allium sativum L. for different durations resulted in signigicant reduction in their hatchability. Maggots hatched from the eggs exposured for 64 h and 72 h were failed to emerge from host larvae. The duration of development stages of E. bombycis was prolonged besides reduction in rate of pupation and adult emergence as the egg exposure period increased. The findings are interpreted as the chronic effects of volatiles of garlic affecting maggots following developmental defects sustainable during embryonic development. The known major chemical components of A. sativum such as allicin, thioacrolein, ajoune, 2-propene sulfenic acid, 2-propene thiol and propylene were presumed to be responsible for the adverse consequences reported in this paper.