Comparison of health inequalities according to socioeconomic status: findings from the fourth Korean working condition survey (a cross-sectional study).

Introduction: this study aims to examine health inequalities among Korean workers by sex, age, education, monthly income, occupation, and employment type and identify groups of workers who may be neglected in the process of resolving health inequalities. Methods: we used data from the Fourth Korean Working Condition Survey conducted by the Korea Occupational Safety and Health Research Institute and compared the number of health symptoms among various groups using the t-test and one-way analysis of variance to determine their health status. We also calculated the Gini index of the number of health symptoms of each group and plotted the Lorenz curve to illustrate health inequalities. Results: we found that the number of health symptoms was higher in groups with lower socioeconomic status (e.g., female, blue-collar workers, older, low education, low monthly income, and self-employed workers). However, the Gini index and Lorenz curve with respect to socioeconomic status indicated that health inequalities were higher among white-collar and permanent workers vis-à-vis blue-collar and self-employed workers, respectively. Further, it was found that health inequalities were higher among males than females with respect to the same occupational groups and employment types. Conclusion: general health policies are often targeted at the socially and economically vulnerable group, but according to the results of this study, it can be considered that there may be subjects who are vulnerable to health problems even in groups that are not socioeconomically vulnerable.

Effect of High Temperature on Walking among Residents of Rural and Urban Communities.

PURPOSE: This study aimed to establish the association between high temperature and walking among residents of rural and urban areas. MATERIALS AND METHODS: This cross-sectional study used data from the Korea Meteorological Administration and the 2018 Community Health Survey to confirm the association between temperature and walking practice. The dependent variable was walking practice. Walking practice was considered if the participants walked for more than 30 minutes a day or more than 5 days a week. The independent variable was the daily maximum temperature (℃) for the preceding 7 days, calculated from the survey date of each participant. A multilevel analysis was conducted to simultaneously consider the individual- and neighborhood-level variables that could affect determining the association between daily maximum temperatures and walking practice. RESULTS: When the daily maximum temperature increased by 1℃, the odds ratio of walking practice decreased to 0.95 (95% confidence interval 0.94-0.97) in rural areas. In contrast, it decreased to 0.98 (95% confidence interval 0.97-1.00) in urban areas, considering both individual- and neighborhood-level factors. Individual- and neighborhood-level determinants of walking practice in rural areas, including educational attainment, marital status, driving a car, subjective health, depression, and meeting neighbors and friends, were confirmed. CONCLUSION: This study confirmed that increased temperature led to more decrease in physical activity levels in rural areas than in urban areas. Physical and environmental approaches to avoid heat are needed to maintain and promote physical activity, since temperatures can reduce physical activity during the hot summer months.

How Does the Involuntary Choice of Self-Employment Affect Subjective Well-Being in Small-Sized Business Workers? A Cross-Sectional Study from the Fifth Korean Working Conditions Survey.

In South Korea, self-employed workers comprise 24.6% of the working population-among which 99.7% were found to operate with less than 50 employees. However, few studies have investigated the effects of an involuntary choice of self-employment. In this study, based on the fifth Korean Working Conditions Survey, the factors affecting subjective well-being and mental health in small business owners with less than 50 employees among service/sales workers, who account for more than half of the self-employed population in Korea, were analyzed by the World Health Organization-Five Well-Being Index, using the Student's t-test, ANOVA and logistic regression analysis. Results showed that the well-being level for those who opted for self-employment involuntarily was lower than those who chose it voluntarily. Then, participants were separated into two groups according to sex; the degree corresponding to the poor well-being score group was compared, and that of the group who chose self-employment because they could not find any other work was significantly higher than that of the group who chose it voluntarily, in both men and women, and this was similar even after correcting for covariance. As the number of people being forced to choose self-employment is expected to further increase after the outbreak of COVID-19, future studies should be conducted to improve subjective well-being of such workers.

The association between direct supervisor's behavior and employee presenteeism in Korean wage workers: findings from the fifth Korean Working Condition Survey.

BACKGROUND: Presenteeism is a phenomenon in which employees go to work, but physical or mental health problems make it impossible for them to properly demonstrate their abilities, and productivity decreases accordingly. Recent studies have considered the behavior of direct supervisors to be an important factor in the pathogenesis of various health-related outcomes. This study aimed to investigate the association between the direct supervisor's behaviors and presenteeism among wage workers in South Korea. METHODS: A total of 25,798 participants from the fifth Korean Working Condition Survey conducted in 2017 were included in the analysis. The behaviors of direct supervisor were assessed by 6 questionnaire items. In this study, the distribution of the scores was categorized into 4 categories (very good, good, bad, and very bad). To assess presenteeism, the corresponding questionnaire item was used. χ2 tests and multiple logistic regression analyses adjusted for general, occupational, and psychosocial factors were performed to determine the association between the behaviors of direct supervisor and presenteeism. RESULTS: Direct supervisor's behavior were significantly associated with presenteeism. The adjusted odds ratios (aORs) of presenteeism in the good, bad, and very bad groups were 1.297 (95% confidence interval [CI]: 1.153-1.458), 1.191 (95% CI: 0.941-1.507), and 1.604 (95% CI: 1.184-2.175), compared with the very good group. Associations between presenteeism and the behaviors of direct supervisor were significant in male workers, but not in female workers. For male workers, the aORs of presenteeism in the good, bad, very bad groups were 1.661 (95% CI: 1.425-1.936), 1.445 (95% CI: 1.053-1.982), 2.340 (95% CI: 1.569-3.491), respectively. CONCLUSIONS: This study suggests that the behavior of a direct supervisor can influence the occurrence of presenteeism, particularly in men. The proper management of senior employee's behaviors is necessary to reduce the risk of presenteeism in the workplace.

Prevalence of Pathogens and Other Microorganisms in Premenopausal and Postmenopausal Women with Vulvovaginal Symptoms: A Retrospective Study in a Single Institute in South Korea.

Background and Objectives: Vaginitis causes vulvovaginal symptoms, including itching, irritation, vaginal discharge, burning, or foul odor. It is one of the most common diseases encountered in gynecologic practice. Hypoestrogenism due to menopause has a considerable negative effect on vaginal health and leads to changes in the vaginal pH and vaginal microflora, which are related to a change in the causes and microorganisms of vaginitis. Thus the aim here was to investigate the prevalence of pathogens and other microorganisms in premenopausal and postmenopausal women with vulvovaginal symptoms, using an STD 12-Multiplex real-time PCR test and routine culture of vaginal discharge. Materials and Methods: From January 2018 to December 2019, records of patients diagnosed with vaginitis at Changwon Gyeongsang National University Hospital were retrospectively reviewed. The premenopausal and postmenopausal subjects were categorized into Group A and Group B, respectively. and the data of symptoms, general characteristics, and results of both STD 12-Multiplex real-time PCR test and routine culture of vaginal discharge were retrieved. Results: On the STD 12-Multiplex real-time PCR test, Gardnerella vaginalis was the most common microorganism in both groups. Ureaplasma parvum was the second most common one, followed by Candida speceies. On the routine culture of vaginal discharge, Escherichia coli was the most common aerobic bacterial microorganism in both groups, followed by Streptococcus agalactiae (Group B Streptococcus, GBS). There was no significant difference between the two groups. Pathogens and other microorganisms of patients with vulvovaginal symptoms that showed a statistically significant difference between the two groups were Ureaplasa parvum, Ureaplasma urealyticulum, Trichomonas vaginalis, and Staphylococcus aureus. Conclusion: In this study, the prevalence of pathogens and other microorganisms in menopausal women with vulvovaginal symptoms did not show a significant difference from premenopausal women. Therefore, management strategies for patients with vulvovaginal symptoms should be developed through accurate diagnosis using appropriate diagnostic methods.

Clinicopathological and ultrasound features of endometrial cancer in postmenopausal women: a retrospective study in a single institute in South Korea.

INTRODUCTION: endometrial cancer is the most common type of cancer in the female genital tract. Most patients are diagnosed during postmenopausal periods. This study aimed to investigate the demographic characteristics as well as cutoff value of endometrial thickness and ultrasound characteristics of endometrial cancer in postmenopausal patients. METHODS: we retrospectively analyzed 244 postmenopausal women who underwent endometrial sampling from February 2016 to December 2019. Information of patients was obtained through medical records. The patients were divided into two groups according to histopathological results. Group A included patients with endometrial cancer and group B included patients with non-malignant lesions. Data were summarized based on demographic and ultrasound characteristics. RESULTS: hypertension and history of endometrial hyperplasia were associated with the incidence of endometrial cancer in this study. Endometrial cancer was diagnosed in all ranges when the endometrial thickness was ≥5 mm. Endometrial fluid collection, with increased endometrial thickness, was a risk factor associated with endometrial cancer. CONCLUSION: regardless of symptoms and risk factors, endometrial histological confirmation in postmenopausal women should be conducted immediately if endometrial abnormalities such as an endometrial thickness ≥5 mm or endometrial fluid collection are detected by transvaginal ultrasound.

Cell Viability and Immune Response to Low Concentrations of Nickel and Cadmium: An In Vitro Model.

Environmental exposure to low concentrations of heavy metals is common in the general population, but the toxicity, immune response mechanisms, and the effects of single and mixed metal exposures have not been clearly identified. In this study, A549 cells and Raw264.7 cells were exposed to low concentrations of the heavy metals nickel (Ni) and cadmium (Cd) for 24, 48, and 72 h, and then cell viability and cytokine levels were analyzed. We found that exposure to low concentrations of Ni (50 nM) or Cd (10 nM) alone did not affect cell viability. However, mixing them together decreased cell viability. In addition, the levels of IL-10, IL-12, and TNF-α decreased with single (only Cd) and mixed (Ni and Cd) exposures. These results show that exposure to low concentrations of heavy metals could affect the normal immune response, even without obvious clinical manifestations. Therefore, chronic exposure to heavy metals might have adverse effects on overall health.

Clinicopathologic characteristics and treatment patterns of pelvic organ prolapse in South Korea.

INTRODUCTION: We investigated the clinicopathologic features, method of treatment, and complications related to the conservative treatment and surgical treatment of patients with pelvic organ prolapse (POP). METHODS: We retrospectively analyzed 288 patients who were diagnosed with POP from January 2007 to December 2017. The patients were divided into two groups according to the treatment method (Group A received conservative treatment and Group B received surgical treatment). The patients' clinicopathologic characteristics, treatment method, and post-treatment complications were compared between groups A and B. RESULTS: Of the total 288 patients, 83 and 205 patients were assigned to Groups A and B, respectively. The most common symptom was a bearing-down sensation (n = 205, 71.2%), which was reported in 51 (61.4%) and 154 (75.1%) patients from Groups A and B, respectively. Among underlying diseases, hypertension was the most common in both groups (40 and 102 patients in Groups A and B, respectively). Overall, 205 patients underwent surgery, 23 underwent vaginal pessary, and 60 performed pelvic floor muscle exercises. The incidence of treatment-related complications was not significantly different between Groups A and B (13.3% vs. 17.6%, p = 0.37). Perioperative complications were noted in 20 (17.8%) patients and vault prolapse requiring subsequent surgery was noted in 16 (14.1%) patients. CONCLUSION: As surgical treatment is associated with recurrence and complications, conservative treatment methods can be initially considered for patients with POP. In this study, there was no difference in the incidence of complications between surgical and conservative treatments. Thus, if required, surgical treatment can be safely performed in patients with POP.

The effect of diabetes on 4-year changes of hearing thresholds in male workers exposed to noise in a single company: a longitudinal study.

BACKGROUND: Recently, several studies have assessed the association between diabetes and hearing impairment. However, the effect of diabetes on hearing impairment is not well known in diabetic patients exposed to noise, a typical cause of hearing impairment. The aim of this study is to longitudinally analyze the effect of diabetes on hearing impairment in workers exposed to similar noise levels from 2013 to 2017 who had experienced little change in their working conditions. METHODS: The study subjects included 2,087 male workers exposed to noise in a single company and who underwent health examinations at the same hospital in Ulsan city in 2013 and 2017. Hearing impairment was defined that a pure-tone average of pure-tone audiometry (PTA) thresholds at 1,000, 2,000, 3,000, and 4,000 Hz was 25 dB and over in both ears. Statistical analyses were conducted using χ2 tests, ANOVA, and Cox proportional hazard models. We analyzed covariates that might affect hearing impairment, including age; working period; levels of total cholesterol, triglyceride, and serum creatinine; smoking and alcohol history; and noise level. RESULTS: The average PTA thresholds and their average changes between 2013 and 2017 were significant in the diabetes mellitus (DM) group than those in the normal and impaired fasting glucose group. Among the subjects with the same status of fasting glucose group in 2013 and 2017, the adjusted hazard ratios for incident hearing impairment among those in the DM group compared to normal group were 3.35 (95% confidence interval [CI], 1.54-7.29) in the left ear and 5.66 (95% CI, 2.01-15.98) in the right ear. CONCLUSIONS: This study suggested that the risk of hearing impairment in the DM group was significantly higher than that in the normal group in both ears, even when exposed to similar noise levels.

Application of cold intolerance symptom severity questionnaire among vibration-exposed workers as a screening tool for the early detection of hand-arm vibration syndrome: a cross-sectional study.

BACKGROUND: The detection rate of hand-arm vibration syndrome (HAVS) is very low in South Korea compared with other countries. The absence of uniform consensus and guidelines for diagnosing HAVS has been presumed to be one of the reasons. The HAVS has various manifestations including cold intolerance and its severity can be measured using the cold intolerance symptom severity (CISS) questionnaire. This study aimed to determine whether the CISS questionnaire, being used as a screening tool, can aid in the early detection of HAVS. METHODS: A total of 76 male workers with vibration-induced symptoms were enrolled as the final study participants. To compare the CISS score of healthy individuals, 41 men who had never been exposed to local vibration were included in the study. In addition to the former medical questionnaire, the participants answered the CISS questionnaire. A statistical analysis was conducted to identify the association of CISS scores with vibration induced symptom and to determine its cut off value. RESULTS: The reliability of the CISS questionnaire was proven to be good, with a total Cronbach's alpha of 0.922. The mean CISS score of the exposed group increased in every vascular stage [stage 0 = 42.6 (18.5); stage 1 = 59.4 (14.1); and over stage 2 = 60.2 (21.6)]. They were significantly higher than that of the non-exposed group. The result was fairly consistent with those in the sensorineural stage. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and area under curve (AUC) of 30 were 88.5, 65.3, 76.1, 82.1 and 0.769, respectively. From the result of logistic regression, the adjusted odds ratio of both components increased by the CISS score grouped by 30s. CONCLUSIONS: The self-reported CISS questionnaire, used to measure the degree of cold intolerance, showed high agreement with the Stockholm classification of HAVS. Hence, we recommend the use of this questionnaire to assess the level of cold intolerance among vibration-exposed workers and detect individuals who are at risk of vibration-induced impairment with a cutoff value of 30. TRIAL REGISTRATION: IRB No. 2018-07-040-001. Registered on 4 September 2018.

Influence of Physical and Musculoskeletal Factors on Occupational Injuries and Accidents in Korean Workers Based on Gender and Company Size.

Though the overall incidence of occupational injuries and accidents has decreased, they continue to happen. Many associated factors are known and managing them with limited resources is difficult. This study evaluates related risk factors and prioritizes their management for reducing occupational injuries and accidents at the workplace. We used data from the 4th Korean Working Condition Survey conducted by the Korea Occupational Safety Health Research Institute from June to September 2014. A total of 14,381 persons (9776 men, 4605 women) were selected; t-test, chi-square test, and logistic regression analyses were performed to analyze data. The influence of physical (vibration, noise, abnormal temperature) and musculoskeletal (awkward posture, handling of heavy objects, repetitive tasks) factors was compared according to gender and company size. The risk of occupational injuries and accidents among men was related to musculoskeletal factors and vibration in companies with "under 50" employees and with awkward posture, vibration, and noise in companies with "50 or above" employees; however, among women in companies with "under 50" employees, it was associated with only vibration. Although we evaluated only a few risk factors, prioritizing them based on gender and company size has provided new valuable information.

Comparison of a 10-Year Cumulative Age-Standardized Incidence Rate of Lung Cancer among Metropolitan Cities in Korea (During the 2000⁻2009 Period): Review of Occupational and Environmental Hazards Associated with Lung Cancer.

In Korea, lung cancer is a common cancer, and has the highest mortality rate in both males and females. Approximately 80% of lung cancer is due to smoking, and the remaining cases are known to be due to genetic factors, history of respiratory disease, infection, diet, and occupational and environmental factors. Since the occupational and environmental hazards may differ from region to region, the lung cancer risk may differ too. To identify this, we selected seven metropolitan cities, and compared occupational and environmental hazards. Furthermore, we calculated smoking rate adjusted standardized rate ratio (ratio of 10-year cumulative age-standardized incidence rate of lung cancer during the 2000⁻2009 period at target region versus reference region) to compare the regional lung cancer risk. The result showed that the emissions and concentrations of air pollutant were higher in high-risk regions, and the risk of lung cancer was significantly elevated in such area. In this study, we simultaneously consider the cumulative incidence, age-standardization and smoking rate adjustment. Therefore, we can conclude that the validity of the finding of this study is higher than that of past studies. In conclusion, the occupational and environmental hazards have an effect on lung cancer.

Low Income as a Vulnerable Factor to the Effect of Noise on Insomnia.

Objective: The present study aimed to examine the potential mediating effect of income level on the association between noise exposure and insomnia. Methods: 706 individuals were evaluated in conjunction with 2014 noise map data from Seoul, South Korea. Cross-sectional analysis was performed to examine differences in noise level according to household income, while three separate logistic regression models were used to examine factors influencing insomnia. Odds ratios (ORs) were calculated after adjusting for depression, anxiety, auditory acuity and noise sensitivity in the first model. Analyses were adjusted for sociodemographic variables in the second model, lifestyle factors and medical illnesses in the third model. Results: Noise level was significantly associated with an increased risk of insomnia in the low-income group, although no such association was observed in the high-income group. Groups exposed to >60 dB of noise (Lden; day-evening-night equivalent) exhibited a 1.79-fold increase in the incidence of insomnia relative to those exposed to <50 dB. The result was significant after adjusting sociodemographic variables, although not significant when adjusted for lifestyle factors and medical illnesses. Conclusion: Individuals with low income may be more vulnerable to the deleterious effects of noise exposure on health. Various aspects including income should be considered to ascertain the influence of noise on insomnia.

Environmental and Body Concentrations of Heavy Metals at Sites Near and Distant from Industrial Complexes in Ulsan, Korea.

BACKGROUND: Industrial pollution may affect the heavy metal body burden of people living near industrial complexes. We determined the average concentrations of atmospheric heavy metals in areas close to and distant from industrial complexes in Korea, and the body concentrations of these heavy metals in residents living near and distant from these facilities. METHODS: The atmospheric data of heavy metals (lead and cadmium) were from the Regional Air Monitoring Network in Ulsan. We recruited 1,148 participants, 872 who lived near an industrial complex ("exposed" group) and 276 who lived distant from industrial complexes ("non-exposed" group), and measured their concentrations of blood lead, urinary cadmium, and urinary total mercury. RESULTS: The results showed that atmospheric and human concentrations of heavy metals were higher in areas near industrial complexes. In addition, residents living near industrial complexes had higher individual and combined concentrations (cadmium + lead + mercury) of heavy metals. CONCLUSION: We conclude that residents living near industrial complexes are exposed to high concentrations of heavy metals, and should be carefully monitored.

Clinicopathologic Characteristics and Causes of Postmenopausal Bleeding in Older Patients.

BACKGROUND: This study aimed to reveal the clinicopathologic features and causes of bleeding in older patients with postmenopausal bleeding (PMB) and to investigate the correlation between the ultrasonographic findings and etiology of PMB. METHODS: We retrospectively analyzed the causes and clinical characteristics of PMB in 498 patients who were diagnosed between January 2007 and December 2017. The population with PMB was divided into 2 groups according to age: Group A (n=204) included individuals more than 65 years of age and group B (n=294) included those less than 65 years of age. Clinical characteristics such as age, parity, underlying conditions, previous surgical history, and previous menopausal hormone therapy were compared between the groups. Cervical cytology testing and transvaginal ultrasonography were performed in all patients with PMB. Endometrial biopsy was performed in all cases of endometrial thickness ≥5 mm. RESULTS: We examined 498 patients with PMB. In group A, atrophic endometrium (n=125, 61.27%) was the most common cause of PMB. Twenty-three patients had gynecological malignancy (cervical cancer: n=12, 5.88%; endometrial cancer: n=8, 3.42%; ovarian cancer: n=3, 1.46%), and 30 patients had benign gynecological disease (endometrial polyp: n=10, 4.90%; submucosal myoma: n=6, 2.94%; uterine prolapse: n=7, 3.42%; cervical dysplasia; n=5, 2.45%; cervical polyp: n=2, 0.98%). Forty patients had endometrial thickness ≥5 mm. Eight patients were diagnosed with endometrial cancer. All cases of endometrial cancer were diagnosed with endometrial thickness >10 mm. CONCLUSION: Atrophic endometrium was the most common cause of PMB in both groups, and approximately 12% of cases were associated with gynecological malignancy in older patients.

Effects of self-reported sensitivity and road-traffic noise levels on the immune system.

Sensitivity to noise, particularly road traffic noise, can increase cortisol levels and result in changes in immune system biomarkers. Therefore, continuous exposure to noise can have an effect on immune function, hormonal levels, and cardiovascular function, leading to hypertension and stress. The purpose of this study was to investigate the changes in stress-and immune system-related biomarkers according to the self-reported sensitivity to noise and exposure to road traffic noise, to ultimately determine the potential effects of noise on health. A survey was conducted through questionnaire (ISO/TS 15666) sent to 172 female subjects in Korea, including 128 from Ulsan and 44 from Seoul. The average noise level was calculated, and blood samples were collected for measurements of cortisol levels, Natural killer (NK) / Natural killer T (NKT) cell populations, and NK cell activity (through measurements of interleukin-12 (IL-12) and interferon-gamma (INF-γ) concentrations). Multivariate linear regression analysis of the measured biomarkers according to the road traffic noise level and self-reported noise sensitivity was conducted adjusting for the effects of age, alcohol status, smoking status, regular exercise, and residence period. IL-12 levels increased, whereas the NKT cell population decreased with increasing noise levels. The results further suggested that cortisol levels are more influenced by the subject's sensitivity to noise than to the level of chronic road traffic noise. Therefore, noise appears to have the largest effect on IL-12 levels as well as the population and activity of NKT cells. In conclusion, our results suggest that low-level road traffic noise and sensitivity to noise can affect health by causing changes in the immune response through mechanisms other than increased cortisol.

The association between cadmium and lead exposure and blood pressure among workers of a smelting industry: a cross-sectional study.

BACKGROUND: Lead and cadmium are harmful heavy metals that are used for a variety of occupational purposes. Considering their potentially hazardous effects on health, studies on the association between exposure to these two heavy metals and health disorders have been actively conducted. This study aimed to determine the association between blood lead and cadmium levels and blood pressure in workers exposed to lead and cadmium in a smelter. METHODS: Nine hundred and sixty-three male workers who worked in a smelter, and underwent medical examinations at the Ulsan University Hospital between January 1 and December 31, 2014, were selected as participants. Among them, 310 subjects whose data on height, weight, blood pressure, fasting blood glucose, lipid profile, and blood lead and cadmium levels were available and who answered the questionnaire were selected as the final participants. We investigated the drinking habit, smoking status, exercise adequacy, and family history of hypertension of these workers using formal questionnaires. A statistical analysis was conducted using Student's t-test, analysis of variance, and linear or logistic regression. RESULTS: The association between blood lead and cadmium levels and blood pressure was analyzed through statistical adjustment of the risk factors of hypertension. Results showed an association between blood cadmium level and blood pressure elevation. However, blood lead level was found to be not correlated with blood pressure elevation. CONCLUSIONS: This study shows the association between blood cadmium level and systolic blood pressure (SBP) and diastolic blood pressure (DBP) elevation. TRIAL REGISTRATION: IRB No. 2017-03-037. Retrospectively Registered 30 March 2017.

Levels of blood lead and urinary cadmium in industrial complex residents in Ulsan.

BACKGROUND: Populations neighboring industrial complexes are at an increased health risk, due to constant exposure to various potentially hazardous compounds released during industrial production activity. Although there are many previous studies that focus on occupational exposure to heavy metals, studies that focused on environmental exposure to lead and cadmium are relatively rare. The purpose of this study is to evaluate the extent of the environmental exposure of heavy metals in residents of industrial area. METHODS: Four areas in close proximity to the Ulsan petrochemical industrial complex and the Onsan national industrial complex were selected to be included in the exposure group, and an area remotely located from these industrial complexes was selected as the non-exposure group. Among the residents of our study areas, a total of 1573 subjects aged 20 years and older were selected and all study subjects completed a written questionnaire. Blood and urine samples were obtained from about one third of the subjects (465 subjects) who provided informed consent for biological sample collection. Total 429 subjects (320 subjects from exposure area, 109 subjects from non-exposure area) were included in final analysis. RESULTS: The geometric mean blood lead level among the subjects in the exposed group was 2.449 µg/dL, which was significantly higher than the non-exposure group's level of 2.172 µg/dL. Similarly, the geometric mean urine cadmium levels between the two groups differed significantly, at 1.077 µg/g Cr. for the exposed group, and 0.709 µg/g Cr. for the non-exposure group. In a multiple linear regression analysis to determine the relationship between blood lead level and related factors, the results showed that blood lead level had a significant positive correlation with age, the male, exposure area, and non-drinkers. In the same way, urine cadmium level was positively correlated with age, the female, exposure area, and smokers. CONCLUSIONS: This study found that blood lead levels and urine cadmium levels were significantly higher among the residents of industrial areas than among the non-exposure area residents, which is thought to be due to the difference in environmental exposure of lead and cadmium. Furthermore, it was clear that at a low level of exposure, differences in blood lead or urine cadmium levels based on age, gender, and smoking status were greater than the differences based on area of residence. Therefore, when evaluating heavy metal levels in the body at a low level of exposure, age, gender, and smoking status must be adjusted, as they are significant confounding factors.

The responses of subjective feeling, task performance ability, cortisol and HRV for the various types of floor impact sound: a pilot study.

BACKGROUND: Recently, noise coming from the neighborhood via floor wall has become a great social problem. The noise between the floors can be a cause of physical and psychological problems, and the different types of floor impact sound (FIS) may have the different effects on the human's body and mind. The purpose of this study is to assess the responses of subjective feeling, task performance ability, cortisol and HRV for the various types of floor impact. METHODS: Ten men and 5 women were enrolled in our study, and the English listening test was performed under the twelve different types of FIS, which were made by the combinations of bang machine (B), tapping machine (T), impact ball (I) and sound-proof mattress (M). The 15 subjects were exposed to each FIS for about 3 min, and the subjective annoyance, performance ability (English listening test), cortisol level of urine/saliva and heart rate variability (HRV) were examined. The sound pressure level (SPL) and frequency of FIS were analyzed. Repeated-measures ANOVA, paired t-test, Wilcoxon signed rank test were performed for data analysis. RESULTS: The SPL of tapping machine (T) was reduced with the soundproof mattress (M) by 3.9-7.3 dBA. Impact ball (I) was higher than other FIS in low frequency (31.5-125 Hz) by 10 dBA, and tapping machine (T) was higher than other FIS in high frequency (2-4 k Hz) by 10 dBA. The subjective annoyance is highest in the combination of bang machine and tapping machine (BT), and next in the tapping machine (T). The English listening score was also lowest in the BT, and next in T. The difference of salivary cortisol levels between various types of FIS was significant (p = 0.003). The change of HRV parameters by the change of FIS types was significant in some parameters, which were total power (TP) (p = 0.004), low frequency (LF) (p = 0.002) and high frequency (HF) (p = 0.011). CONCLUSIONS: These results suggest that the human's subjective and objective responses were different according to FIS types and those combinations.

Effect of shift work on hypertension: cross sectional study.

BACKGROUND: The need of efficient resource management and full-time accessibility to resources has increased with the development of industry, resulting in the increase of shift workers. Previous researches of past decades show that there are various health effects on shift workers. However, the definition and the form of shift work have varied from each research and occupational harmful factors except for shift work have not been excluded completely in previous researches. Therefore, in this research, we tried to find out the effect of shift work focusing on the hypertension. To complement previously mentioned weakness of other researches, we performed our research on participants to whom we could minimize other risk factors excluding shift work. METHODS: This research examined 1,953 petrochemical plant male workers (shift work 1,075, day worker 878) who did medical checkup from 1st Jan. 2014 to 31th Dec. 2014 in a general hospital located in Ulsan, based on their medical records and questionnaires. With the questionnaire, we found out their basic information including age, social status, occupational history, and we took their physical measurements. RESULTS: Compared to day workers, shift workers' odds ratio of developing hypertension was 1.31 (95% CI 0.98-1.75). After adjusting confounding variables, adjusted odds ratio for entire subjects was 1.51 (95% CI 1.11-2.06). Also, for subjects who were in continuous service for over 20 years, odds ratio was 1.51 (95% CI 1.08-2.11). CONCLUSIONS: Shift workers had a higher chance of hypertension than day workers do. Particularly, the longer the workers work continuously, the risk of hypertension getting higher.