Assessment of radiation exposure from cesium-137 contaminated roads for epidemiological studies in Seoul, Korea

OBJECTIVES: We aimed to assess the radiation exposure for epidemiologic investigation in residents exposed to radiation from roads that were accidentally found to be contaminated with radioactive cesium-137 (137Cs) in Seoul. METHODS: Using information regarding the frequency and duration of passing via the 137Cs contaminated roads or residing/working near the roads from the questionnaires that were obtained from 8875 residents and the measured radiation doses reported by the Nuclear Safety and Security Commission, we calculated the total cumulative dose of radiation exposure for each person. RESULTS: Sixty-three percent of the residents who responded to the questionnaire were considered as ever-exposed and 1% of them had a total cumulative dose of more than 10 mSv. The mean (minimum, maximum) duration of radiation exposure was 4.75 years (0.08, 11.98) and the geometric mean (minimum, maximum) of the total cumulative dose was 0.049 mSv (<0.001, 35.35) in the exposed. CONCLUSIONS: An individual exposure assessment was performed for an epidemiological study to estimate the health risk among residents living in the vicinity of 137Cs contaminated roads. The average exposure dose in the exposed people was less than 5% of the current guideline.

Assessment of radiation exposure from cesium-137 contaminated roads for epidemiological studies in Seoul, Korea

OBJECTIVES: We aimed to assess the radiation exposure for epidemiologic investigation in residents exposed to radiation from roads that were accidentally found to be contaminated with radioactive cesium-137 (137Cs) in Seoul. METHODS: Using information regarding the frequency and duration of passing via the 137Cs contaminated roads or residing/working near the roads from the questionnaires that were obtained from 8875 residents and the measured radiation doses reported by the Nuclear Safety and Security Commission, we calculated the total cumulative dose of radiation exposure for each person. RESULTS: Sixty-three percent of the residents who responded to the questionnaire were considered as ever-exposed and 1% of them had a total cumulative dose of more than 10 mSv. The mean (minimum, maximum) duration of radiation exposure was 4.75 years (0.08, 11.98) and the geometric mean (minimum, maximum) of the total cumulative dose was 0.049 mSv (<0.001, 35.35) in the exposed. CONCLUSIONS: An individual exposure assessment was performed for an epidemiological study to estimate the health risk among residents living in the vicinity of 137Cs contaminated roads. The average exposure dose in the exposed people was less than 5% of the current guideline.

Prevalence and Epidemiological Features of Moyamoya Disease in Korea

OBJECTIVE: The objectives of the present study were to investigate the annual detection rate of patients with Moyamoya disease (MMD) and to describe the prevalence and epidemiological features of the Moyamoya patients in Korea. MATERIALS AND METHODS: The authors analyzed the epidemiological data of Korean patients taken from the National Health Insurance Corporation in Korea among Moyamoya patients who were treated from 2004 until 2008. RESULTS: Based on 2004 data, 2,539 MMD patients were treated in Korea and the prevalence rate was 5.2 per 100,000 people. There were 2,987 in 2005, 3,429 in 2006, 4,051 in 2007, and 4,517 cases in 2008, and the prevalence rates per 100.000 people were 6.3, 7.0, 8.6, and 9.1, for those respective years. This represents an annual increase of 15% of new cases during this period. In 2008, 466 people were newly diagnosed with MMD, representing an incidence rate of 1 per 100,000 persons. The gender ratio was 1,547 men (34%) and 2,970 women (66%). Women had a higher incidence rate than men (1.94 times). There were two age peaks: teenagers and those in their forties. CONCLUSION: The present study shows that the number of Moyamoya patients in Korea is increasing. This increase could partly be explained by a recent increase in newly diagnosed cases, suggesting that a more careful consideration of the disease and better diagnostic techniques should be promoted among clinicians.

Human Factors Involved in Traffic Accidents and Unsafe Driving Behaviors of Taxi Drivers / 대한산업의학회지

OBJECTIVE: This study investigated the driving habits of taxi drivers, in order to examine the characteristics of human factors causing traffic accidents and unsafe driving behavior and to determine any relevancy among them. METHOD: Taxi drivers (N=335) answered a questionnaire investigating various measures of human factors, unsafe driving behaviors, and number of traffic accident experiences in the previous year. In factor analysis, the characteristics of human factors were classified into 5 common factors: job, mental health, age, health habit and sleep factor. A contextual mediated model was proposed to distinguish the distal (5 common factors) and proximal (unsafe driving behaviors) factors in predicting traffic accident involvement by hierarchical multiple regression. RESULT: In hierarchical multiple regression, job factor(beta: 0.122), sleep factor (beta: 0.114) and unsafe driving behaviors (beta: 0.018) yielded a direct effect on the rate of traffic accidents. Mental health factor beta: 6.429), job factor (beta: 1.319) and health habit factor(beta: 1.177) yielded a indirect effect on the rate of traffic accidents by unsafe driving behaviors. CONCLUSION: Various human factors co-related by the unique characteristics that exist in the taxi service industry have significant effects on the rate of traffic accidents mediated by unsafe driving behaviors. Therefore a proper countermeasure against these factors should be established in order to effectively reduce the rate of taxi accidents.

The Association of Carbon Disulfide Poisoning with Heart Rate Variability / 대한산업의학회지

OBJECTIVES: Mass poisoning by carbon disulfide (CS2) occurred in a viscose rayon factory in Korea. Up until 1998, 830 employees, including 38 who had died, were diagnosed with CS2 poisoning. Among the CS2 poisoned subjects, heart rate variability (HRV) was evaluated to investigate whether the toxic effect of CS2 persists after the exposure has ceased. The dose-response relationship between carbon disulfide exposure and HRV was also evaluated. METHODS: The case group was comprised of 71 retired male workers diagnosed as being CS2 poisoned. The control group was comprised of 127 males of same age-range who had no history of CS2 exposure and cardiovascular diseases. Information on individual age, height, weight, cigarette smoking, alcohol drinking, regular exercise, medical and occupational history, chest x-ray, and ECG recording of the two groups were collected through a self-administered questionnaire and with a medical examination. Time (maximum, average, minimum RR interval) and frequency domain measures (low frequency - LF, high frequency - HF, total power spectrum TPS, and LF/HF ratio) of the two groups were analyzed. CS2 exposure indices of the case group (duration of employment, exposure level per work department, cumulative exposure index and duration of retirement) were investigated. RESULTS: Using a univariate analysis, the frequency domain measures for the case group were significantly lower than those in the control group, except for HF. In the multivariate analysis, previous history of CS2 poisoning was inversely related to all frequency domain parameters and it significantly affected the LF (p<0.05) and the LF/HF ratio (p<0.05). There was no significant dose-response relationship between CS2 exposure indices and HRV parameters in the case group. CONCLUSION: This study suggests that further studies are necessary to evaluate the residual effects of CS2 poisoning even after the CS2 exposure has ceased.

Brain MRI Findings of Carbon Disulfide Poisoning

OBJECTIVE: To evaluate the findings of brain MRI in patients with carbon disulfide poisoning. MATERIALS AND METHODS: Ninety-one patients who had suffered carbon disulfide poisoning [male:female=87:4; age, 32-74 (mean 53.3) years] were included in this study. To determine the extent of white matter hyperintensity (Grade 0-V) and lacunar infarction, T2-weighted MR imaging of the brain was performed. RESULTS: T2-weighted images depicted white matter hyperintensity in 70 patients (76.9%) and lacunar infarcts in 27 (29.7%). CONCLUSION: In these patients, the prevalent findings at T2-weighted MR imaging of the brain were white matter hyperintensity and lacunar infarcts. Disturbance of the cardiovascular system by carbon disulfide might account for these results.

Assessing Muscle Tensions During VDT Works with Surface Electromyography / 대한산업의학회지

OBJECTS: Thls study was designed to assess muscle tensions while working at a YDT workstation with surface electromyography (SEMG). METHODS: Variables texted were desk height, monitor positon on the desk, distance from edge of the desk to the keyboard. Eleven female volunteers working in the tele-com munication company were seated at an ergonomically adjusted workstation. They were assigned to a task of typing for 5 minutes and were given a 10 minutes resting with hands in their lap. For the initial experiment, the desk height was fixed to standard desk height(65.0 cm) recommended by ANSI and latter adjusted to a higher desk height (72.8 cm) for this study such that the subjects experienced slight elevation of shoulders. The monitor position initially at the center on the desk and latter left site of the desk (45o from monitorneck axles). The keyboard was positioned to an optimal distance (15 cm from the desk edge) and an abnormal distance (30 cm). Five muscle groups (paraspinal muscles, upper trapezium muscle, supraspinatus muscle, infraspinatus muscle, and rhomboid muscle) were selected for the study. The data of SEMG were analyzed by 2x2x2xs mixed factorial design. RESULTS: The results were as follows: 1. SEMG activity recorded from the paraspinal muscles were significantly higher when the angle of the monitor adjusted to 45 degree from the center of the desk.. 2. SEMG activity recorded from the upper trapezius/supraspinatus/infraspinatus muscles were significantly higher when the hight of the desk was elevated from the recommended height.3. SEMG activity from the rhomboid muscle showed no significantiy difference in all test conditions. CONCLUSIONS: The results of thls study confirm that the helght of a VDT workstation and the angle of the monitor are risk factors of upper extremity cumulative trauma disorders. Also SEMG would be useful for measuring muscle activities during workstation assessment.