BACKGROUND AND OBJECTIVES: Heart rate variability has been known to be a prognostic factor of heart disease. However, determinants of heart rate variability in general korean population without clinical heart disease have not been studied. Objectives of this study were to measure heart rate variability in general population and to investigate clinical determinants of heart rate variability. METHODS:Heart rate variability measures were obtained by LRR-03TM and MemCalcTM software (GMS, Tokyo, Japan) from public officials in a district of Seoul and their families(n=69). Predictors of heart rate variability included age, gender, heart rate, smoking status, systolic blood pressure, diastolic blood pressure, serum total cholesterol, HDL-cholesterol. Univariate analysis and analysis of variance of low frequency power(0.04-0.15 Hz), high frequency power(0.15-0.30 Hz), and total power spectrum in relation to explanatory variables were done. In order to select determinants of heart rate variability, multiple linear regression model of each heart rate variability measure was created and stepwise selection method was applied. RESULTS: Analysis of variance showed that older age, higher heart rate, body mass index > or =27, systolic blood pressure > or =140 mmHg, diastolic blood pressure > or =90 mmHg, and serum total cholesterol > or =240 mg/dl were negatively associated with one or more heart rate variability measures. Serum HDL-cholesterol > or =35 mg/dl was positively associated with low and high frequency power. Multiple linear regression analyses showed that age and heart rate were the major determinants, gender and cardiovascular risk factors such as diastolic blood pressure, HDL-cholesterol, and smoking contributed to one or more heart rate variability measures. CONCLUSIONS: Age, heart rate, gender, and cardiovascular risk factors must be considered when evaluating heart rate variability.
Blood Pressure ; Body Mass Index ; Cholesterol ; Heart Diseases ; Heart Rate* ; Heart* ; Linear Models ; Risk Factors ; Seoul ; Smoke ; Smoking

OBJECTIVES: Ischemic heart disease (IHD) is a major cause of death in Korea and known to result from several occupational factors. This study attempted to estimate the current magnitude of IHD mortality due to occupational factors in Korea. METHODS: After selecting occupational risk factors by literature investigation, we calculated attributable fractions (AFs) from relative risks and exposure data for each factor. Relative risks were estimated using meta-analysis based on published research. Exposure data were collected from the 2006 Survey of Korean Working Conditions. Finally, we estimated 2006 occupation-related IHD mortality. RESULTS: For the factors considered, we estimated the following relative risks: noise 1.06, environmental tobacco smoke 1.19 (men) and 1.22 (women), shift work 1.12, and low job control 1.15 (men) and 1.08 (women). Combined AFs of those factors in the IHD were estimated at 9.29% (0.3-18.51%) in men and 5.78% (-7.05-19.15%) in women. Based on these fractions, Korea's 2006 death toll from occupational IHD between the age of 15 and 69 was calculated at 353 in men (total 3,804) and 72 in women (total 1,246). CONCLUSION: We estimated occupational IHD mortality of Korea with updated data and more relevant evidence. Despite the efforts to obtain reliable estimates, there were many assumptions and limitations that must be overcome. Future research based on more precise design and reliable evidence is required for more accurate estimates.
Cardiovascular Diseases ; Cause of Death ; Female ; Humans ; Korea ; Male ; Myocardial Ischemia ; Noise ; Occupations ; Risk Factors ; Smoke ; Tobacco

Once released into the air, humidifier disinfectants became tiny nano-size particles, and resulted in chemical bronchoalveolitis. Families had lost their most beloved members, and even some of them became broken. Based on an estimate of two million potential victims who had experienced adverse effects from the use of humidifier disinfectants, we can say that what we have observed was only the tip of the iceberg. Problems of entire airways, as well as other systemic effects, should be examined, as we know these nano-size particles can irritate cell membranes and migrate into systemic circulation. The story of humidifier disinfectant is not finished yet.
Cell Membrane ; Disinfectants* ; Humans ; Humidifiers* ; Ice Cover

This paper reviews the published literature that is concerned with color vision impairment from industrial and environmental exposure to neurotoxic substances, and we evaluated whether testing for color vision impairment could be an affordable procedure for assessing these neurotoxic effects. In general, most cases of congenital color vision impairment are red-green, and blue-yellow impairment is extremely rare. However, most of the acquired color vision impairment that is related to age, alcohol or environmental factors is blue-yellow impairment. Therefore, many studies have been performed to identify this relationship between exposure to neurotoxic substances, such as organic solvents and heavy metals, and the prevalence of blueyellow color vision impairment. The test for color vision impairment is known to be very sensitive to the early signs of nervous system dysfunction and this can be useful for making the early diagnosis of neurotoxic effects from exposure to very low concentrations of toxic substances.
*Color Perception Tests ; Color Vision Defects/*chemically induced/diagnosis ; Early Diagnosis ; Hazardous Substances/*toxicity ; Humans ; Neurotoxicity Syndromes/*diagnosis/pathology ; Solvents/adverse effects

BACKGROUND: Spirometry should be compared with the normal predictive values obtained from the same population using the same procedures, because different ethnicity and different procedures are known to influence the spirometry results. This study was performed to obtain the normal predictive values of the Forced Vital Capacity(FVC), Forced Expiratory Volume in 1 Second(FEV1), Forced Expiratory Volume in 6 Seconds(FEV6), and FEV1/FVC for a representative Korean population. METHODS: Based on the 2000 Population Census of the National Statistical Office of Korea, stratified random sampling was carried out to obtain representative samples of the Korean population. This study was performed as a part of the National Health and Nutrition Survey of Korea in 2001. The lung function was measured using the standardized methods and protocols recommended by the American Thoracic Society. Among those 4,816 subjects who had performed spirometry performed, there was a total of 1,212 nonsmokers (206 males and 1,006 females) with no significant history of respiratory diseases and symptoms, with clear chest X?rays, and with no significant exposure to respiratory hazards subjects. Their residence and age distribution was representative of the whole nation. Mixed effect models were examined based on the Akaike's information criteria in statistical analysis, and those variables common to both genders were analyzed by regression analysis to obtain the final equations. RESULTS: The variables affecting the normal predicted values of the FVC and FEV6 for males and females were age2, height, and weight. The variables affecting the normal predicted values of the FEV1 for males and females were age2, and height. The variables affecting the normal predicted values of the FEV1/FVC for male and female were age and height. CONCLUSION: The predicted values of the FVC and FEV1 was higher in this study than in other Korean or foreign studies, even though the difference was < 10%. When compared with those predicted values for Caucasian populations, the study results were actually comparable or higher, which might be due to the stricter criteria of the normal population and the systemic quality controls applied to the whole study procedures together with the rapid physical growth of the younger generations in Korea.
Age Distribution ; Censuses ; Family Characteristics ; Female ; Forced Expiratory Volume ; Humans ; Korea ; Lung ; Male ; Nutrition Surveys ; Quality Control ; Spirometry* ; Thorax

In order to provide necessary information for better health of workers through understanding the actual status of the industries adopting shift systems. The data were gathered from a stratified random sample of 347(0.5%) firms selected out of about 70,000 manufacturing industries throughout the nation in 1993 stratification during sampling was by industrial group and number of workers. The major findings obtained from 288 firms surveyed completely were as follows: 1. About 20.2% of the 288 firms were adopting shift systems and shiftworkers accounted for about 25.1% of the total work force in 288 firms. 2. The bigger number of workers was, the higher the adopting rate of shift system was. 3. The rate of having welfare facilities such as dining room, commuting bus, washing facilities, and health care room etc. was higher in the industries adopting shift systems. 4. The major industrial groups adopting shift systems were the rubber & plastic goods manufacturing industry (54.1 per 100 firms) and the textile manufacturing industry (44.8 per 100 firms). However the proportion of shiftworkers was higher in the textile manufacturing industry (70.5 per 100 firms) and the electronics industry (57.9 per 100 firms). 5. The most predominant work schedule was the weekly rotating, semi-continuos 2-crew 2-shift system (47.5%). 6. In the industries adopting shift systems, shiftworkefs had an adjusted average of 0.29 spells per 100 workers (O.14-0.45 in 95% C.I) compared to 0.23 spells per 100 nonshift dayworkers (0.15-0.31 in 95% C.I) for 1 month. 7. Also in the industries adopting shift systems, the adjusted average annual turn-over rate of shiftworkers was 13.07 per 100 workers (12.03-14.12 in 95% C.I) compared to 10.18 per 100 nonshift dayworkers(9.53-10.82 in 95% C.I).
Appointments and Schedules ; Delivery of Health Care ; Plastics ; Rubber ; Textiles ; Transportation

OBJECTIVES: The increased prevalence of asthma over the last 30 years has been reported from many different countries, including Korea. The increased prevalence may be due to increased exposure to indoor air pollutants. METHODS: In this study, the relationship between residential environments and airway hyper-responsiveness has been examined among 280 family members. The bronchial hyper-responsiveness was expressed as the log-transformed slope of FEV decrease over the log-transformed dose of methacholine concentration(BRindex). Simple regression analysis was done for the effect of sex, age, atopic status, and residential environments including active and passive smoking exposures on airway responsiveness. Based on simple regression results, multiple rwegression analysis was performed for total group and also according to sex. RESULTS: The mean of BRindex of residents living in gas boiler heating houses was higher than that of central heating system (p=0.014). Smoking status was a significant determinant of bronchial hyper-responsiveness in both genders; male(p=0.017), female (p%.022). In the male group the mean of BRindex of current smokers was significantly higher than those of ex-smokers and non-smokers, and the mean of BRindex of passive smokers was higher than that of non-smokers, but statistical significance was border-line(p=0.069). In female group, the mean of BRindex of kerosene stove users was higher than that of non-users(p=0.057). CONCLUSIONS: This study suggests that indoor air pollutants including type of heating, passive smoking and kerosene stove use can contribute to the increase in asthma prevalence in Korea.
Air Pollutants ; Air Pollution, Indoor ; Asthma ; Female ; Heating ; Hot Temperature ; Humans ; Kerosene ; Korea ; Male ; Methacholine Chloride ; Prevalence ; Smoke ; Smoking ; Tobacco Smoke Pollution

Effect of shift work on worker's health, family and social life was investigated at a automobile manufacturing plant in Inchon. In total, 2488 shift workers and 599 non-shift workers completed self administered questionnaire in their sleep pattern, subjective gastrointestinal symptoms, prevalent chronic disease status, general well-being schedule, family and social life. More shift workers complained of sleep disturbance, poor sleep quality, tiredness at awakening, and sleepiness in work than non-shift workers. More shift workers also complained of gastrointestinal disturbance than non-shift workers. Worker's mental health was assessed by General Well-Being Schedule(GWB) questionnaire developed for the U.S. Health and Nutrition Examination Surveys(HANES I). The percentage of severely distressed shift workers was significantly higher than that of non-shift workers(p<0.01). Among subscores in General Well-Being Schedule, anxiety, depression, positive well-being, vitality, and general health subscale of shift workers were lower than those of non-shift workers (p<0.05). In terms of family and social life, there was no significant difference between two groups. Multiple logistic regression analysis was done for discrete variables which showed statistically significant difference between shift and non-shift group. The variables included in analysis were sleep disturbance symptoms, gastrointestinal complaints, and distress level calculated from GWB score. Age, tenure, smoking, alcohol drinking, and exercise were adjusted as confounding factors and odds ratios for above symptoms due to shift work were calculated. Odds ratios (ORs) for sleep disturbance symptoms ranged from 0.52 to 3.59. ORs for gastrointestinal complaints ranged from 1.19 to 1.34. OR for distress level was 1.31. We concluded that shift workers are suffered from physical and psychological ailments due to shift work and interventional methods for preventing worker's health from adverse effects of shift work are needed.
Alcohol Drinking ; Anxiety ; Appointments and Schedules ; Automobiles* ; Chronic Disease ; Depression ; Family Health* ; Humans ; Incheon ; Logistic Models ; Mental Health ; Odds Ratio ; Plants* ; Questionnaires ; Smoke ; Smoking

OBJECTIVES: The effect of mercury on the cardiovascular system has recently been reported on, but the mechanisms as well as its nature of this effect still need to be confirmed. In this study, the mercury in the hair of a community population was analyzed in relation to the cardiac autonomic activity. METHODS: A hair sample was obtained from the occiput area and the mercury in the hair was analyzed by using a Direct Mercury Analyzer. We measured the cardiovascular risk factors, including total cholesterol, triglyceride, blood pressure, and the body mass index (BMI). Heart rate variability was assessed for 5 minutes, in the time and frequency domain, by using SA-3000P from the Medi-core(R). company. The association between the mercury in the hair and heart rate variability was assessed after controlling for the other cardiovascular risk factors. RESULTS: The mean age of the 671 total subjects was 36 years. The geometric mean of the hair mercury was 0.90 ppm. The hair mercury level was elevated in males, adults, smokers and drinkers. Hair mercury and age, the systolic and diastolic blood pressure, total cholesterol, triglyceride, LDL cholesterol and BMI were all positively correlated. However, hair mercury and heart rate, HDL cholesterol, standard deviation of the NN intervals (SDNN), total power (TP), low-frequency (LF), high- frequency (HF) were negatively correlated. In the higher mercury group, heart rate, SDNN, LF and HF indices were significantly lower compared with those of the lower mercury group. Heart rate was decreased 2.6 beats/min, Ln (HF) was decreased 0.131 msec2 and HF norm was decreased 2.550 with a 1 ppm increase of Ln (Hg), according to multiple linear regression analysis after controlling for age, gender and other cardiovascular risk factors. CONCLUSION: This cross-sectional study showed that mercury may affect the cardiac autonomic activity through parasympathetic dysfunction.
Adult ; Autonomic Nervous System ; Blood Pressure ; Body Mass Index ; Cardiovascular System ; Cholesterol ; Cholesterol, HDL ; Cholesterol, LDL ; Cross-Sectional Studies ; Hair ; Heart ; Heart Rate ; Humans ; Linear Models ; Male ; Risk Factors

Social inequality in adverse birth outcomes has been demonstrated in several countries. The present study examined the separate and joint effects of parental education and work in order to investigate the causal pathways of social class effects on adverse birth outcomes in Korea. The occurrence of low birth weight, preterm births, and intrauterine growth retardation was examined among 7,766,065 births in Korea from 1995 to 2008. The effect of social inequality, as represented by parental education and work, was examined against adverse birth outcomes using multivariate logistic regression after controlling for other covariates. Parental education had the most significant and greatest effect on all three adverse outcomes, followed by parental work and employment, which had lesser effects. For adverse birth outcomes, the gap between educational levels increased steadily in Korea from 1995 to 2008. Throughout the analysis, the effect of maternal manual work on adverse birth outcomes was apparent in the study results. Given this evidence of social inequality in education and employment, social interventions should aim at more in-depth and distal determinants of health.
Adolescent ; Adult ; Educational Status ; Employment ; Female ; Fetal Growth Retardation/*epidemiology ; Humans ; Infant, Low Birth Weight ; Infant, Newborn ; Logistic Models ; Male ; Middle Aged ; Mothers ; Odds Ratio ; Parents ; Premature Birth/*epidemiology ; Republic of Korea/epidemiology ; *Social Class ; Time Factors ; Young Adult