• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.26 no.1
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• pp.1-10
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• 2016

Objectives: The aim of this study is to review the results of exposure to chemicals and to extremely low frequency(ELF) magnetic fields generated in wafer fabrication operations in the semiconductor industry. Methods: Exposure assessment studies of silicon wafer fab operations in the semiconductor industry were collected through an extensive literature review of articles reported until the end of 2015. The key words used in the literature search were "semiconductor industry", "wafer fab", "silicon wafer", and "clean room," both singly and in combination. Literature reporting on airborne chemicals and extremely low frequency(ELF) magnetic fields were collected and reviewed. Results and Conclusions: Major airborne hazardous agents assessed were several organic solvents and ethylene glycol ethers from Photolithography, arsenic from ion implantation and extremely low frequency magnetic fields from the overall fabrication processes. Most exposures to chemicals reported were found to be far below permissible exposure limits(PEL) (10% < PEL). Most of these results were from operators who handled processes in a well-controlled environment. In conclusion, we found a lack of results on exposure to hazardous agents, including chemicals and radiation, which are insufficient for use in the estimation of past exposure. The results we reviewed should be applied with great caution to associate chronic health effects.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.26 no.1
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• pp.58-63
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• 2016

Objectives: One major limitation encountered in retrospective exposure assessment for epidemiological study is the lack of exposure records and information maintained by companies which if they existed would allow the estimation of past exposure to hazardous operations and agents. This study developed a job-specific questionnaire(JSQ) to estimate exposure profiles among semiconductor workers, including operation and job. Methods: This JSQ can be directly applied to workers who work or have worked in a wafer fabrication or a chip packaging and assembly facility. Results and Conclusions: We used this JSQ to obtain past exposure information from semiconductor workers via face-to-face investigation. Major contents include questions on the facilities, operations and jobs to which they have been exposed since they entered employment in the semiconductor industry. The total number of questions in the JSQ is 18. Responses to this JSQ can be used not only to estimate retrospective exposure to operations and jobs in the semiconductor industry, but also to associate with the risk of all causes of death and risk of disease, including cancer.

• 대한예방의학회:학술대회논문집
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• 1994.02a
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• pp.417-425
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• 1994

Although animal studies have been used most often for quantitative risk assessment, it is generally recognized that well-conducted epidemiologic studies would provide the best basis for estimating human risk. However, there are several features related to the design and analysis of epidemiologic studies that frequently limit their usefulness for quantitating risks. The lack of accurate information on exposure in epidemiologic studies is perhaps the most frequently cited limitation of these studies for risk assessment. However. other features of epidemiologic study design, such as statistical power, length of follow-up, confounding, and effect modification, may also limit the inferences that can be drawn from these studies. Furthermore, even when the aforementioned limitations are overcome, substantial uncertainty exists concerning the choice of an appropriate statistical (or biologic) model for extrapolation beyond the range of exposures observed in a particular study. This paper focuses on presenting a review and discussion of the methodologic issues involved in using epidemiologic studies for risk assessment. This review concentrates on the use of retrospective, cohort, mortality studies of occupational groups for assessing cancer risk because this is the most common application of epidemiologic data for quantitative risk assessment (QRA). Epidemiologic data should not be viewed as a panacea for the problems inherent in using animal bioassay data for QRA. Rather, information that can be derived from epidemiologic and toxicologic studies complement one another, and both data sources need to be used to provide the best characterization of human risk.

• Journal of Environmental Health Sciences
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• v.38 no.4
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• pp.277-290
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• 2012

Objectives: Diesel engine exhaust (DE) accounts for a significant percentage of air pollutants that are associated with various health outcomes including mortality, asthma, chronic bronchitis, respiratory tract infection, etc. In June, 2012, the International Agency for Research on Cancer (IARC) released the assessment results that classified DE as "carcinogenic to humans" (Group 1). This review is therefore focused on the lung cancer risks of DE. Methods: Literatures were searched using PubMed with key words of "diesel exhaust", "lung cancer", and other related terms for the period between 1990 and 2012. A total of 295 articles were searched and sixteen epidemiologic studies were identified as potentially relevant. Results: Sixteen epidemiologic studies about the lung cancer risks of workers exposed to DE in various occupations were summarized in two tables, 1) retrospective cohort studies and 2) case-control studies. Increased lung cancer risk, although not always smoking adjusted, was observed in 6 out of 8 retrospective cohort studies and 4 of 8 case-control studies. Conclusions: Diesel fuel is widely used in Korea. Exposure to DE is confirmed to be a human carcinogen by IARC. Noncancer health risks of DE also need careful attention as DE is a major source of fine-particle pollution. Along with the efforts for reducing the DE emission through improvements of diesel engines and fuel, and the use of alternative fuels, comprehensive health risk assessment of DE should be conducted to minimize the adverse health effects.

• Journal of dental hygiene science
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• v.24 no.1
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• pp.22-28
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• 2024

Background: Particulate matter (PM) has been extensively observed due to its negative association with human health. Previous research revealed the possible negative effect of air pollutant exposure on oral health. However, the predictive model between air pollutant exposure and the prevalence of periodontitis has not been observed yet. Therefore, this study aims to propose a predictive model for the number of patients with periodontitis exposed to PM and atmospheric factors in South Korea using deep learning. Methods: This study is a retrospective cohort study utilizing secondary data from the Korean Statistical Information Service and the Health Insurance Review and Assessment database for air pollution and the number of patients with periodontitis, respectively. Data from 2015 to 2022 were collected and consolidated every month, organized by region. Following data matching and management, the deep neural networks (DNN) model was applied, and the mean absolute percentage error (MAPE) value was calculated to ensure the accuracy of the model. Results: As we evaluated the DNN model with MAPE, the multivariate model of air pollution including exposure to PM_2.5, PM₁₀, and other atmospheric factors predict approximately 85% of the number of patients with periodontitis. The MAPE value ranged from 12.85 to 17.10 (mean±standard deviation=14.12±1.30), indicating a commendable level of accuracy. Conclusion: In this study, the predictive model for the number of patients with periodontitis is developed based on air pollution, including exposure to PM_2.5, PM₁₀, and other atmospheric factors. Additionally, various relevant factors are incorporated into the developed predictive model to elucidate specific causal relationships. It is anticipated that future research will lead to the development of a more accurate model for predicting the number of patients with periodontitis.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.11 no.2
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• pp.161-168
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• 2001

The types of exposure data needed in an industry-based study depend on the diseases of interest and the study design to be used. The best situation occurs when we have quantified personal exposure estimates for the agents of interest, the least informative case occurs when we have only knowledge of the fact of employment in a plant, industry, or trade where exposure probability is high. Exposure information for most industry-based studies falls somewhere between these tow extremes. Job exposure matrices(JEM) are designed to link information on occupation with information on exposure to specific workplace hazards. Some forms of systematic error of bias may be less likely to occur in studies that utilize job-exposure matrices to indirectly infer exposures from job titles than in studies that assess exposures by asking subjects about their past exposure. JEM can be used effectively in industry-based studies for historic cohort studies, case-control study to assist with the retrospective assessment of occupational exposures among workers whose individual exposure histories are unavailable. JEM generally consist of a computerized database that links information about job categories and likely exposures. These two major axes may be stratified by calendar time. This article reviews the design of JEM in support of industry-based studies. Specific matrices may find broader applicability along with the increasing availability of detailed hygienic data.

• BMB Reports
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• v.48 no.4
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• pp.209-216
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• 2015

Stress is now recognized as a universal premorbid factor associated with many risk factors of various chronic diseases. Acute stress may induce an individual's adaptive response to environmental demands. However, chronic, excessive stress causes cumulative negative impacts on health outcomes through "allostatic load". Thus, monitoring the quantified levels of long-term stress mediators would provide a timely opportunity for prevention or earlier intervention of stressrelated chronic illnesses. Although either acute or chronic stress could be quantified through measurement of changes in physiological parameters such as heart rate, blood pressure, and levels of various metabolic hormones, it is still elusive to interpret whether the changes in circulating levels of stress mediators such as cortisol can reflect the acute, chronic, or diurnal variations. Both serum and salivary cortisol levels reveal acute changes at a single point in time, but the overall long-term systemic cortisol exposure is difficult to evaluate due to circadian variations and its protein-binding capacity. Scalp hair has a fairy predictable growth rate of approximately 1 cm/month, and the most 1 cm segment approximates the last month's cortisol production as the mean value. The analysis of cortisol in hair is a highly promising technique for the retrospective assessment of chronic stress. [BMB Reports 2015; 48(4): 209-216]

• Safety and Health at Work
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• v.6 no.1
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• pp.35-38
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• 2015

Background: Organizational changes that involve healthcare hospital departments and care services of health districts, and ongoing technological innovations and developments in society increasingly expose healthcare workers (HCWs) to work-related stress (WRS). Minimizing occupational exposure to stress requires effective risk stress assessment and management programs. Methods: The authors conducted an integrated analysis of stress sentinel indicators, an integrated analysis of objective stress factors of occupational context and content areas, and an integrated analysis between nurses and physicians of hospital departments and care services of health districts in accordance with a multidimensional validated tool developed in Italy by the National Network for the Prevention of Work-Related Psychosocial Disorders. The purpose of this retrospective observational study was to detect and analyze in different work settings the level of WRS resulting from organizational changes implemented by hospital healthcare departments and care services of health districts in a sample of their employees. Results: The findings of the study showed that hospital HCWs seemed to incur a medium level risk of WRS that was principally the result of work context factors. The implementation of improvement interventions focused on team development, safety training programs, and adopting an ethics code for HCWs, and it effectively and significantly reduced the level of WRS risk in the workplace. Conclusion: In this study HCW resulted to be exposed to occupational stress factors susceptible to reduction. Stress management programs aimed to improve work context factors associated with occupational stress are required to minimize the impact of WRS on workers.

• Journal of The Korean Society of Clinical Toxicology
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• v.13 no.2
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• pp.62-70
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• 2015

Purpose: Cardiac complications may occur in cases of organophosphate (OP) poisoning. However, a few studies regarding patterns of cardiac toxicity as determined by transthoracic echocardiography (TTE) after exposure to OP have been reported. In the current study, the authors examined cardiac functions using TTE in patients with myocardial injury caused by exposure to OP. Methods: A retrospective review was conducted on 16 consecutive cases of OP poisoning with myocardial injury (defined as elevated troponin I within 48 hours of arrival at the regional emergency center in South Korea and diagnosed and treated at the center from January 2012 to November 2014. Results: TTE was performed in 11 (69%) of the 16 patients with an elevated troponin I (TnI) level within 48 hours. Of these 11 patients, 5 patients (45.5%) exhibited reduced ejection fraction (EF), and 3 exhibited regional wall motion abnormality (RWMA). Two patients (18.2%) had both reduced systolic function and RWMA. Two of the 5 patients with reduced EF returned to normal systolic function, however two patients did not regain normal systolic function after admission. One patient expired due to multiple organ failure, and 4 patients were transferred with a moribund status. Twelve of 15 patients who survived to discharge (at 4 to 35 months) were followed. Five of these patients died during follow-up and 7 survived without further complications. Conclusion: OP can cause reversible cardiac dysfunction including reduced systolic function and RWMA. Serum TnI may be useful for initial assessment of cardiac function during the workup of patients suffering from OP poisoning. After the initial assessment of cardiac enzyme, further evaluation with TTE in patients with abnormal cardiac enzyme will be necessary to understand the cardiac toxicity.

• Journal of Trauma and Injury
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• v.35 no.1
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• pp.12-18
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• 2022

Purpose: Pedicle screw fixation provides 3-column stabilization, multidimensional control, and a higher rate of interbody fusion. Although computed tomography (CT) is recommended for the postoperative assessment of pedicle screw fixation, its use is limited due to the radiation exposure dose. The purpose of this preliminary retrospective study was to assess the clinical usefulness of low-dose mobile cone-beam CT (CBCT) for the postoperative evaluation of pedicle screw fixation. Methods: The author retrospectively reviewed postoperative mobile CBCT images of 15 patients who underwent posterior pedicle screw fixation for spinal disease from November 2019 to April 2020. Pedicle screw placement was assessed for breaches of the bony structures. The breaches were graded based on the Heary classification. Results: The patients included 11 men and four women, and their mean age was 66±12 years. Of the 122 pedicle screws, 34 (27.9%) were inserted in the thoracic segment (from T7 to T12), 82 (67.2%) in the lumbar segment (from L1 to L5), and six (4.9%) in the first sacral segment. Although there were metal-related artifacts, the image of the screw position (according to Heary classification) after surgery could be assessed using mobile CBCT at all levels (T7-S1). Conclusions: Mobile CBCT was accurate in determining the location and integrity of the pedicle screw and identifying the surrounding bony structures. In the postoperative setting, mobile CBCT can be used as a primary modality for assessing the accuracy of pedicle screw fixation and detecting postoperative complications.