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Shift work that interferes with normal sleep patterns, is known to be a cause of sleep disturbance and has been studied through various occupational groups. However, it is not known which shift type is better for sleep health.This study included 568 firefighters. Sleep quality was evaluated using Pittsburgh Sleep Quality Index. Sleep quality was categorized into 2 groups; good quality (≤ 5 points) and poor quality (≥ 6 points). Demographic variables, depression, anxiety, type of shift, and job were collected by self-reported questionnaires. The χThree hundred thirty-seven firefighters (59.3%) have poor sleep quality. Compared to day workers, the odds ratios (ORs) of poor sleep quality were 2.169 (95% confidence interval: 1.137-4.134) in 6-day cycle, 2.161 (1.150-4.062) in 9-day cycle, 1.805 (1.087-2.997) in 21-day cycle, and 1.485 (0.718-3.069) in 3-day cycle. The ORs of poor sleep quality were 1.697(1.021-2.823) in fire suppression and 2.325 (1.213-4.455) in emergency medical service compared to administration.All shift work type except for the 3-day cycle was associated with poor sleep quality compared to day work.

Background: This cross-sectional study assessed the sleep quality using the ActiGraph and investigated the relationship between the parameters of sleep assessment and the type of shift work in Korean firefighters. Methods: The participants were 359 firefighters: 65 day workers (control group) and 294 shift workers (shift work group: 77 firefighters with 3-day shift, 72 firefighters with 6-day shift, 65 firefighters with 9-day shift, and 80 firefighters with 21-day shift). Sleep assessments were performed using the ActiGraph (wGT3X-BT) for 24 hours during day shift (control and shift work group) and night shift and rest day (shift work group). The participants recorded bed time and sleep hours during the measurement period. Results: Sleep efficiency, total sleep time, and percentage of wake after sleep onset during night work were lower in the shift work group than control group (p

Background Noise has been a major issue in children due to its effect on emotional symptoms and sleep problems. The present study investigated the effect of noise on sleep and autonomic activity in children according to three variables, namely, road traffic noise, aircraft noise, and noise sensitivity (NS). Methods The study is epidemiological in nature. A total of 474 subjects of four elementary schools were evaluated in conjunction with the 2014 noise map data gathered from two metropolitan regions, Seoul and Ulsan, in South Korea. Each subject completed the children's sleep habits questionnaire, and heart rate variability (HRV) was recorded. Analysis of covariance was performed using monthly income as a covariate. Results Aircraft noise was associated with night waking (P = 0.047), whereas no significant association was observed between sleep and road traffic noise. After stratifying by NS, no significant results were obtained for road traffic noise. However, high levels of aircraft noise in the high-NS group were associated with high degrees of bedtime resistance (P = 0.049). In terms of HRV, no significant difference was observed in the results between groups. Conclusion Road traffic noise did not significantly alter sleep or autonomic activity in children, whereas aircraft noise exerted a negative effect on sleep. The findings suggest that the impact of noise on sleep in children varies depending on noise sources., Graphical Abstract

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.

Background: Recent research indicates that shift work is associated with neurocognitive function. However, studies that examine the association between shift work and neurocognitive function in firefighters have not yet been performed. We examined the effect of shift work on neurocognitive function in firefighters by measuring and comparing neurocognitive function before and after night shift. Methods: 352 firefighters from eight fire stations in South Korea were included in this study. We performed neurocognitive function test using central nervous system vital signs (CNSVS) during daytime work and on the next day after night work. We performed paired t-tests to assess differences between neurocognitive function before and after night work. We also compared neurocognitive function in insomnia and depression. We used a general linear model to analyze the associations between shiftwork schedule and the changes in neurocognitive function. Results: The neurocognitive function significantly decreased in six domains (composite memory, verbal memory, visual memory, complex attention, psychomotor speed, and motor speed) as did the neurocognitive index on the next day after night work compared with during day work. These decreased domains were the same following night work regardless of the type of shift work. Conclusion: Night work in firefighters may cause neurocognitive decline.

(1) Study Objectives: By investigating the change of cortisol levels during shift cycles among professional firefighters in Korea, this study aims to evaluate the difference between individuals&rsquo, stress response and the recovery of their circadian rhythm after working night shifts. (2) Methods: A total of 325 shift firefighters, who were working in 3, 6, 9, or 21 day cycles, participated in the study. Their urinary and serum cortisol levels were measured during the day (09&ndash, 18), during the night (18&ndash, 09), and every 24 h (09&ndash, 09) per shift cycle, and adjustments were made for confounding factors. (3) Results: Serum cortisol levels were significantly increased after working during the night or for 24 h compared with that of working throughout the day. However, whether working night or 24 h shifts, the serum cortisol levels were undoubtedly different based on the 3, 6, 9, or 21 day cycles. In all shift cycles, the urinary cortisol level decreased during the night or throughout the 24 h shifts compared with sleeping during this time, but this was considered to be significantly applicable only to those working in 21 day cycles. Additionally, in serial measurements, the recovery of urinary cortisol secretion after a night or 24 h shift was successful for individuals working in 9 day cycles, but the recovery was delayed for those working in 6 or 21 day cycles. (4) Conclusions: After analyzing the urine cortisol levels, the study indicates that only subjects working in 9 day cycles fully recovered their circadian rhythm while those working in 6 day or 21 day cycles did not completely recover. Therefore, it is important to recognize how stressful night shifts can be, and it is crucial to enhance firefighters&rsquo, current shift cycles in order to allow sufficient recovery of their circadian rhythm as well as the prevention of disrupting their circadian rhythm after working at night. Further research is necessary to take into account the amount of work load, the challenges of being sleep deprived, and the individual&rsquo, s capacity to overcome sleepiness.

Study Objectives Shift work is known to be detrimental to an individual’s health as it disrupts the circadian rhythm and is a risk factor for cancer. It has been reported that elevated fibroblast growth factor (FGF)-23, increased serum soluble α-klotho, and decreased vitamin D3 are associated with cancer progression. We studied the relationship between shift work and the levels of FGF-23, α-klotho, and vitamin D3 amongst firefighters, as they work in long shifts outside the traditional daytime schedule. Methods The study consisted of 450 participants who were firefighters. We measured FGF-23, α-klotho, and vitamin D3 levels in their blood and a set of questionnaires were given to the participants to evaluate their health habits. After determining and adjusting for potential confounding factors, we compared the levels of FGF-23, α-klotho, and serum vitamin D3 by job and shift types. Results FGF-23 and α-klotho levels were significantly higher in shift workers than traditional day workers, and in 3-day cycle shift workers than workers with another shift schedule. When the levels of these substances were compared based on different types of jobs, firefighters had a lower level of vitamin D3. We conclude that shift work is positively correlated with the levels of FGF-23 and α-klotho. Conclusions Levels of FGF-23 and α-klotho were linked to shift work and job types. Although vitamin levels did not differ by shift types, vitamin D3 levels were lower in firefighters. These findings suggest that high levels of FGF-23 and α-klotho are potential risk factors for cancer among firefighters.

Purpose Work-related asthma (WRA) occupies about 10%-30% of all asthma cases. Among 2 subtypes of WRA (occupational asthma [OA] and work-exacerbated asthma [WEA]), the rate of WEA has been reported to increase recently. WRA is described as having worse characteristics than non-WRA (NWRA), while WEA is known to show similar severity to OA in terms of symptoms and exacerbations. However, these data were mainly based on indirect surveys. Ulsan is a highly industrialized city in Korea; therefore, it is estimated to have a high incidence of WRA. This study aimed to identify the characteristics of WRA in the city. Methods This was a prospective asthma cohort study of individuals diagnosed with asthma and treated at Ulsan University Hospital between Jan 2015 and Dec 2016. Baseline characteristics and work-related inquiry (9 questionnaires) were investigated at enrollment. Various severity indices and job change were then investigated for the longitudinal analysis at 12 months after enrollment. Results In total, 217 asthma patients completed the study. WRA accounted for 17% (36/217), with an equal number of WEA and OA (18 patients each). Before the work-related survey, only 33% (n = 12) of WRA patients (22% [4/18] of WEA and 44% [8/18] of OA) were diagnosed with WRA by the attending physicians. Compared to the NWRA group and the OA subgroup, the WEA subgroup had more outpatient visits, more oral corticosteroids prescriptions, and trends of low asthma control test scores and severe asthma. The rate of job change was markedly lower in the WEA subgroup than in the OA subgroup (20% vs. 5%). Conclusions The overall prevalence of WRA (17%) was similar to those of previous studies, but the share of WEA was high (50% of WRA). WEA was more severe than OA or NWRA. The possible reason for this severity is ongoing workplace exposure.

Objective The effect of acute noise on cognitive function has long been a topic of study, yet these effects remain a serious problem for learning performance in school children. Methods From November 15, 2010 to December 8, 2010, we enrolled 268 students from three elementary schools (135 boys and 133 girls, 10-12 years old) in Ulsan, Korea. The study subjects were divided into two groups according to their test conditions (background versus additional noise), and tests were conducted using psychological examination tools. Chi-square tests and general linear models were used to assess the differences of impacts on cognition between the two groups. Results After adjusting for socio-demographic covariates, the noise significantly affected the results of full-scale IQ, verbal IQ, Continuous Performance Test scores, and Children's Color Trails Test and Stroop test scores. The groups at high risk of learning difficulties were more affected by noise than low-risk groups. Conclusion These findings suggest that noise is hazardous to the attention and performance of elementary school students, particularly for groups at greater risk for poor academic achievement. Additional studies are needed to identify subject-specific levels of noise that can affect attention and cognitive function.

Introduction. We first examined the association of an ocular refractive error with allergic conjunctivitis in school children and then examined this association in children attending a suburban school and an urban school. Methods. We enrolled 426 children attending a primary school in a suburban area and 550 children attending a primary school in an urban area which had a higher level of air pollution. Allergic conjunctivitis was defined as the diagnosis of this condition at any time during a child’s life. The ophthalmic examinations included measurements of visual acuity and refraction, and a slit lamp examination. Skin prick tests were also performed at each school during 2018. The significance of associations was determined by the calculation of odds ratios (ORs) and 95% confidence intervals (CIs). Results. Astigmatism (increase of 1 cylindrical diopter) was associated with allergic conjunctivitis in children overall (OR = 1.287, 95% CI = 1.010 to 1.642) and in children attending the urban school (OR = 1.408, 95% CI = 1.029 to 1.926), but not in children attending the suburban school (OR = 1.040, 95% CI = 0.672 to 1.610). Allergic conjunctivitis also had a higher prevalence among children attending the urban school. The urban school had higher levels of air pollutants than the suburban school. Skin prick tests indicated that the major allergens in children with allergic conjunctivitis were house dust mites and various types of pollen. Conclusion. Astigmatism is associated with allergic conjunctivitis in children attending an urban school.

Objective The aim of this study was to estimate the progress of insomnia prevalence and incidence over the past several years. Also, this study compared survival rates between individuals with and without insomnia.Methods The National Health Insurance Service-National Sample Cohort (NHIS-NSC) from 2002–2013 was used for this study. Prevalent cases of insomnia were defined using ICD-10 codes F51.0 or G47.0, or a prescription of sedatives. Cox’s proportional hazard analysis was conducted to compare survival rates between insomnia patients and people without insomnia.Results In 2013, there were 46,167 (5.78%) insomnia patients over 20 years old in this cohort. Insomnia was more common among women and the elderly. Annual incidence over the past several years remained steady but the prevalence increased. The survival of insomnia patients was lower than that of people without insomnia, and the hazard ratio for overall mortality was 1.702 (p

Objectives/Hypothesis To investigate the relationship between sleep-disordered breathing (SDB) and nocturnal enuresis (NE) in children and to prospectively evaluate the effectiveness of adenotonsillectomy on resolving enuresis in indicated SDB patients with NE. Methods We prospectively collected data from 183 children (121 males, mean age 8.17 ± 2.84 years) who underwent adenotonsillectomy to treat SDB between July 2011 and July 2013, and analyzed the prevalence of NE. Before and 3 months after surgery, all parents were requested to answer a self-reported SDB scale questionnaire (22 questions, 0–22 points) and a NE questionnaire (episodes of enuresis per month). Paired t test, Student t test, and Chi-square test were used to analyze the data. Results Overall prevalence of NE was 9.3% (17 patients) preoperatively and 1.5% postoperatively (four patients). After adenotonsillectomy, prevalence of NE and the mean SDB scale were significantly decreased (both P values < 0.001). After adenotonsillectomy, 13 of the 17 NE patients (76.5%) showed complete resolution. There was significantly higher prevalence of NE in patients with obstructive sleep apnea (OSA) than those without OSA (13.1%, 14 of 107 vs. 3.9%, 3 of 76; P = 0.036). Conclusion There is strong association between NE and SDB, and adenotonsillectomy can markedly improve enuresis in the majority of children with NE and SDB. Levels of Evidence 4. Laryngoscope, 126:1241–1245, 2016

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&ndash, 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.

Introduction Traumatic stress like experience in witnessing a suicide or accidents can cause post-traumatic stress disorder (PTSD). Firefighters are exposed to traumatic stresses due to their professional nature. It is known that dealing with extra stress after the event can be a risk factor in development of the disease. Thus, we aim to study to see whether occupational stress can act as a risk factor in development of PTSD. Methods 310 among total 315 professional firefighters were given written informed consents and answered self -reported questionnaires. Impact of Event Scale-Revision (IES-R), Life Event Checklist (LEC) and Korean Occupational Stress Scale (KOSS) questionnaires were used to assess the PTSD and determine the level of occupational stress. SPSS 21.0 was used for all statistical analysis. Results According to the IES-R questionnaire, 75 out of 310 subjects (24.2%) were in risk of developing PTSD. The LEC score which is designed to screen one’s experience of potentially traumatic events was significantly high in the PTSD risk group compared to no risk group (p=0.008). Total KOSS score of PTSD risk group (49.21±10.90) was also significantly higher than that of no risk group (45.17±10.86) (p=0.005). Conclusion The prevalence of PTSD was significantly higher in firefighters than general population in several studies, and result of our study also corresponds well. Furthermore we could confirm that the more impact traumatic stress one has experienced in life, the more likely it is to develop PTSD and occupational stress is playing as a risk factor in the development of the disease. By identifying the level of occupational stress and the impact of traumatic event using simple self-reported questionnaires, it would be easier to detect the people who are in risk of developing PTSD and take early medical intervention to prevent the progression of PTSD.

Background Oxidative stress is defined as an imbalance between the level of reactive oxygen species and antioxidant mechanisms. Compared with asthma, the role of oxidative stress in allergic rhinitis (AR) has received little attention. Objective To investigate the association between overall systemic oxidative stress and AR. Methods We used a propensity score matching case-control study and selected 90 children who had experienced AR in the previous year. This AR group was then matched with 90 healthy children who comprised the control group. Propensity score matching, a statistical matching technique that accounts for the conditional probability of receiving an exposure given a vector of measured covariates, is used to reduce selection bias and potential confounders in observational study. Serum total antioxidant status (TAS) and total oxidant status (TOS) levels were determined using a commercially available assay kit. Medical records and personal information were also reviewed. Results No statistically significant differences were found between patients with regard to age, sex, height, weight, educational level of parent, monthly household income, or distance of home from a main road. The mean TAS and TOS levels in the patient group were significantly higher than those of the control group ( P = .03 and .048, respectively). The oxidative stress index, which is defined as the ratio of TOS to TAS, also increased in the AR group with statistical propensity ( P = .08). In a multivariate logistic analysis, only TAS and TOS levels were significantly associated with increased risk of allergic rhinitis. Conclusion Patients with AR have systemically elevated oxidative stress and systemically elevated TAS levels.

*Department of Occupational & Environmental Medicine, University of Ulsan College of Medicine, Korea **Environmental Health Center, University of Ulsan College of Medicine, Korea ABSTRACTObjectives: This study aims to investigate the correlations between the prevalence of allergic rhinitis (AR) andcytokines among elementary school children in an industrial city, Ulsan, South Korea, and to identify majorenvironmental risk factors associated with AR prevalence. Methods: We conducted a case-control study in June 2009 and February 2010 in order to evaluate therelationship between AR and related cytokines. Data on physician-treated prevalence over the past 12 monthsand potential risk factors for AR were compiled through a questionnaire from a survey of 339 schoolchildrenliving in different urban environments. Logistic regression analysis was carried out with propensity scorematched data (n=180) to assess the influences of cytokines (IL-13, IL-33, IL-4 and IL-5) on AR prevalence andto determine which environmental factors affected AR.Results: In univariate analysis, the AR prevalence was influenced by family history of AR (mother andsiblings), environmental factors (odor condition and irritated symptoms of air pollution), and indoorallergens (D. farinae and D. pteronyssinus). The t-test demonstrated that eosinophils, Immunoglobulin E(IgE), and interleukins (IL-13 and IL-5) were statistically significantly different according to treatment ofallergic rhinitis over the preceeding 12 months. The results of the multiple logistic regression analysisshowed that a statistically significant association between several factors (such as irritated symptoms of airpollution (OR 4.075, CI 1.735-9.568), IL-13 (OR 0.825, CI 0.734-0.928), odor condition (OR 2.409, CI0.908-6.389), and AR history of siblings (OR 2.217, CI 0.999-4.921)) and the prevalence of AR was foundafter adjusting for confounders. Conclusion: These results suggest that AR prevalence is significantly associated with cytokine level, geneticbackground, and outdoor environmental factors. Although living in a polluted area and genetic background cancontribute to an increased risk of childhood AR, cytokine level should be considered as an important factor inthe treatment of AR in the last 12 months.Keywords: Allergic rhinitis, case-control study, cytokine, environmental risk factors, propensity scorematching

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., Graphical Abstract

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

Environmental noise is known to cause noise annoyance. Since noise annoyance is a subjective indicator, other mediators-such as noise sensitivity-may influence its perception. However, few studies have thus far been conducted on noise annoyance in South Korea that consider noise sensitivity and noise level simultaneously. The aim of this study was to evaluate the correlations between noise sensitivity or noise level and noise annoyance on a large scale in South Korea. This study estimated the level of noise exposure based on a noise map created in 2014; identified and surveyed 1836 subjects using a questionnaire; and assessed the impact of transportation noise and noise sensitivity on noise annoyance. The result showed that noise exposure level and noise sensitivity simultaneously affect noise annoyance, and noise sensitivity has a relatively larger impact on noise annoyance. In conclusion, when study subjects were exposed to a similar level of noise, the level of noise annoyance differed depending on the noise sensitivity of the individual.

We present data from the Korean National Health and Nutritional Examination Survey (KNHANES) 2010-11 on the distribution of blood lead levels, and examine their association with iron deficiency in a representative sample of the adolescent Korean population.This study was based on data obtained from KNHANES, in which a rolling sampling design was used to perform a complex, stratified, multistage probability cluster survey of a representative sample of the non-institutionalized civilian population in South Korea. Serum ferritin was categorized into three levels: low (serum ferritin15.0μg/L), low normal (serum ferritin 15.0-30.0μg/L for girls and 15.0-50.0 for boys), and normal (serum ferritin ≥30.0μg/L for girls and ≥50.0 for boys), and its association with blood lead levels was assessed after adjustment for various demographic and lifestyle factors.The geometric mean (GM) of blood lead in the low serum ferritin group was significantly higher than that in the normal group among boys but not girls. After controlling for covariates, multiple regression analysis showed that blood lead was inversely correlated with serum ferritin levels in boys and pre-menarche girls only.The present study shows that iron deficiency increases blood lead levels in a representative sample of the male and pre-menarche female adolescent population, as evaluated in KNHANES. The confounding effect of estrogen on blood lead levels should be considered.

To determine whether blood lead concentration is elevated in iron-deficient infants, blood lead and serum ferritin concentrations, serum iron/transferring iron-binding capacity (Fe/TIBC) and complete blood counts were measured in 30 iron deficient and 35 control infants, aged 6-24 months. All 30 iron-deficient infants received iron supplementation (ferric hydroxide-polymaltose complex, 6mg/kg Fe(3+)/day) for 1-6 months. Blood lead concentrations were measured in 18 of the iron deficient infants after their ferritin levels returned to the normal range. The geometric mean blood lead concentration was higher in iron deficient than in control infants (1.846 vs. 1.416μg/dL). After iron therapy, the blood lead levels of iron-deficient infants decreased significantly compared with pre-treatment levels (1.785 vs. 2.386μg/dL), and the hemoglobin and ferritin concentrations increased significantly. These findings indicate that iron deficiency increases blood lead concentrations in infants with very low blood lead concentrations.

Background The purpose of this study was to investigate hearing threshold changes of workers with unilateral conductive hearing loss who were exposed to workplace noise for 8-years. Methods Among 1819 workers at a shipyard in Ulsan, 78 subjects with an air-bone gap ≥10 dBHL in unilateral ears were selected. Factors that could affect hearing were acquired from questionnaires, physical examinations, and biochemistry examinations. Paired t-test was conducted to compare the hearing threshold changes over time between conductive hearing loss (CHL) ear and sensorineural hearing loss (SNHL) ear. Results The study included male subjects aged 48.7 ± 2.9, having worked for 29.8 ± 2.7 years. Hearing thresholds increased significantly in CHL ears and SNHL ears at all frequencies (0.5–6 kHz) during follow-up period (p

Background: Work-related asthma(WRA) occupies about 30% of all asthma;two subtypes of WRA,occupational asthma(OA) and work-exacerbated asthma(WEA) accounts for about 2/3 and 1/3 of WRA,respectively.However,these data were mainly based on indirect surveys.Ulsan is the most industrialized city in Korea,therefore it is expected that Ulsan has many WRA patients. Objectives: To know the exact prevalence of WRA in an industrialized city through a prospective clinical asthma cohort,and to know characteristics of WRA. Methods: Since JAN 2015, those who had been diagnosed with asthma at Ulsan Univ.Hosp. were recruited prospectively.At enrollment,clinical and work-related data were gathered.Every 6 months,the revaluation was performed. Results: Study is expected to last for at least 2 years,and the present data are interim results of 166 enrolled asthma patients for 1 year.WRA was 16.3%(27/166);OA and WEA occupied 77.8% and 22.2% of WRA.Before surveying work-relatedness,only 29.6% had been assessed as WRA by attending physicians.The major causes of WRA were chemical materials and exhaust gas/smoke in OA,whereas isocyanate and metal/metal-working fluid in WEA.Comparing OA,WEA had a long duration and a non-eosinophilic phenotype.Otherwise, there were no between-group differences in OA and WEA.Through revaluation at 6 months,we could know that severe asthma was more common in WEA than in OA (50% vs 10%, p=0.04). Conclusions: The prevalence of WRA was lower in the present study than in previous indirect studies.Work-relatedness survey should be routinized in all new asthmatics.The causes of WRA were different in OA and WEA.Compared to OA,WEA had a long duration,a non-eosinophilic phenotype,and was associated with severe asthma.

Objectives: This study aims to investigate the AD (allergic diseases: asthma, allergic rhinitis and atopic dermatitis) prevalence among elementary schoolchildren in an industrial city, Ulsan, and identify major environmental risk factors associated with AD prevalence. Methods: Data on the physician-diagnosed prevalence over the past 12 months and potential risk factors of AD were collected through a questionnaire from a 2009-2010 survey of 4,067 schoolchildren living in different urban environments. The logistic regression analysis was performed to assess differences in AD prevalence among the areas and to determine which environmental factors impacted AD. Results: Our survey results showed that the AD prevalence rate ranged between 26.2% and 35.9%. Children living in polluted areas (near industrial and central urban areas) had about a 10% higher prevalence of AD than did those living in coastal or suburban residences. The Chi-Square test demonstrated that this local difference was statistically significant before and after adjustment of major confounders such as parental AD history and parental education. The results of the logistic regression analysis showed a statistically significant association between several environmental factors (ventilation in winter, odor conditions and exposure to traffic smoke, and outdoor pollution) and the prevalence of AD found by multivariate model after adjusting confounders. Conclusion: These results suggest that local differences in AD prevalence are significantly associated with outdoor environmental factors. Although there are likely to be other risk factors for AD, living in a polluted area and exposure to high levels of air pollutants can contribute to an increased risk of childhood AD.

This study compared indoor air quality of homes in which elementary school children with and without (case and control) allergic rhinitis live in the Ulsan metropolitan region (UMR). A total of 58 homes (case and control: 29, respectively; children aged 7 to 12 years) was selected for indoor air quality measurements. The concentrations of all general indoor air pollutants, except , in the case group were much higher than those in the control group. In particular, the average concentrations of and in the case group were statistically significantly (p in the case and control groups and in the case group exceeded the standard level. Some components of aldehydes and ketones and VOCs indicated large difference of average concentrations between two groups, but there were no statistically significant differences.

Department of Environmental Health, Graduate School of Public Health, Seoul National University, Seoul, Korea*Environmental Health Center, College of Medicine, University of Ulsan, Ulsan, Korea**Department of Occupational and Environmental Medicine, College of Medicine, University of Ulsan, Ulsan, KoreaABSTRACTObjectives: The purpose of this study was to determine house dust mite concentrations in living rooms andbedding materials in atopic case-control groups. Methods: Fifty four homes with children suffering atopic diseases as cases and fifty one homes without atopicdiseases as controls were selected after diagnosis at three elementary schools in Ulsan City. Dust samples werecollected from the living rooms and bedding materials in each home during summer and winter with a vacuumcleaner and analyzed for house dust mites using enzyme-linked immunosorbent assay (ELISA). Environmentalfactors and family history were surveyed during sampling. Results: Both species of house dust mite Dermatophagoides farina (Der f 1) and Dermatophagoidespteronyssinus (Der p 1) were found in all homes. Derf1 concentrations were much higher than Der P1concentrations, both in atopic homes (1518.9 vs. 27.0 ng/g. dust, respectively) and non-atopic homes (810.8 vs.44.3 ng/g. dust, respectively). Der f 1 concentrations were significantly higher in the atopic group than in thenon-atopic group (atopic: 1518.9 ng/g.dust, non-atopic: 810.8 ng/g.dust, p = 0.035). However, total house dustmite Der p 1 concentrations were significantly higher in the non-atopic group than in the atopic group (atopic:27.0 ng/g.dust, non-atopic: 44.3 ng/g.dust, p = 0.035). Multiple regression implied that mothers with familyhistory of atopic diseases (OR = 4.79, 95% CI = 1.81-12.69), Der f 1 concentrations (OR = 1.74, 95% CI = 1.07-2.81), and air freshener use (OR = 4.60, 95% CI = 1.72-12.34) had significant associations with atopic children. Conclusion: House dust mite Der f 1 concentrations were associated with atopic children. This study suggeststhat parents should reduce house dust mite Der f 1 concentrations through environmental controls. Keywords: case-control, atopic disease, house dust mite, environmental factor, allergen

National Institute of Environmental Research, Incheon, KoreaObjectives : The aim of this study was to investigate the sleep patterns of South Korean elementary school children and whether the differences in sleep patterns were related to behavior, emotional problems, attention and academic performance. Method : This study included a community sample of 268 boys and girls from fourth-, fifth- and sixth-grade classes in a South Korean metropolitan city from November to December 2010. The primary caregivers completed a questionnaire that included information on demographic characteristics, as well as the Child’s Sleep Habit Questionnaire (CSHQ), the Korean version of Child Behavior Checklist (K-CBCL), the Korean version of the Learning Disability Evaluation Scale (K-LDES), the Korean version of ADHD Rating Scale (K-ARS) and the Disruptive Behavior Disorder Scale (DBDS). We conducted analyses on the CSHQ individual items, between the subscales, on the total scores and on the K-CBCL, the K-LEDS, the K-ARS and the DBDS. Results : Based on the findings from the CHSQ, the subjects had significantly higher scores for bedtime resistance (9.18±2.17), delayed sleep onset (1.32±0.62), the sleep duration (4.19±1.52) and daytime sleepiness (14.10±3.55) than the scores from the previous reports on children from western countries. The total CHSQ score showed positive correlations to all subscales of the K-CBCL : withdrawn (r=0.24, p＜.005), somatic complaint (r=0.24, p＜.005) and anxious/depressive (r=0.38, p＜.005). Bedtime resistance was associated with oppositional defiant disorder (r=0.15, p＜.05) and a positive correlation was demonstrat-ed between sleep anxiety and the oppositional defiant disorder score (r=0.13, p＜.05), night waking and the conduct disorder score (r=0.16, p＜.05). Delayed sleep onset was related with low performance on the K-LDES with respect to thinking (r=-0.17, p＜.05) and mathematical calculation (r=-0.17, p＜.05).Conclusion : The results of this study reconfirm Korean children’s problematic sleep patterns. Taken together the results provide

Previous studies have suggested that development of Mycobacterium kansasii lung disease (MKLD) was associated with COPD, pneumoconiosis, aging, male, immunosuppression, alcohol, malignancy, and certain occupations such as mining and sandblasting. However, previous studies were outdated and used non-comparative statistical methods. We aimed to determine the current risk factors for developing MKLD in Korea by using appropriate statistical techniques. Eighty-six MKLD patients were identified through a search of the Ulsan University Hospital database between January 2010 and December 2014. These cases were matched with 172 controls who had normal respiratory systems in a health examination during the same period (matching variables, age and sex; case: control ratio of 1:2). Clinical and demographic characteristics were gathered by reviewing the medical record and telephone survey. Multivariate logistic regression analyses were performed to evaluate risk factors for developing MKLD. Multivariate analysis showed that occupation in heavy industries (adjusted odds ratio (aOR) 6.41, 95% confidence interval (CI) 2.19−18.74, P = .001) and low body mass index (BMI) (aOR [per kg/m2] 0.73, 95% CI 0.63−0.85, P

We utilized a mice model of Parkinsonism: (1) to evaluate 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced neurotoxicity; and (2) to evaluate whether manganese (Mn) exposure can affect MPTP-induced neurotoxicity. A 2 × 3 experimental design (MPTP ×± Mn) was as follows: SS, MPTP(-) × Mn(-); SLMn, MPTP(-) × low Mn(+); SHMn, MPTP(-) × high Mn(+); MpS, MPTP(+) × Mn(-); MpLMn, MPTP(+) × low Mn(+); MpHMn, MPTP(+) × high Mn(+). We administered MPTP (30 mg/kg per day) to male C57BL/6 mice intraperitoneally, once a day for 5 days. Subsequently, mice were treated with either 2 or 8 mg/kg of MnCl2.4H2O intraperitoneally, once a day for 3 weeks. Blood and striatal Mn levels were elevated in the Mnexposed groups. The number of tyrosine hydroxylase (TH)-immunoreactive (ir) neurons in the substantia nigra pars compacta were decreased significantly in the MPTP-exposed groups. The densities of TH-ir axon terminals in caudate-putamen (CPU) were significantly decreased in the MPTP-treated groups. However, Mn treatment did not affect MPTP neurotoxicity. The densities of glial fibrillary acidic protein (GFAP)-ir astrocytes in the CPU or globus pallidus were significantly increased in the MPTP-treated groups. Concentrations of dopamine in the striatum were decreased significantly in the MPTP-exposed groups only, but Mn had no effect.

This study aims to investigate the allergic disease (AD) prevalence for elementary school children in an industrial city of Ulsan and identify major environmental risk factors associated with AD prevalence. Data on the physician-diagnosed prevalence in the past 1 year and potential risk factors of AD (asthma, allergic rhinitis and atopic dermatitis) were collected by a questionnaire including ISAAC questions from the 2009-2010 survey of 4,067 children living in different urban environments. Exposure to outdoor air pollution was estimated by using annual mean concentrations of pollutants (PM10, O3, NO2, SO2 and CO) obtained from monitoring sites near the participant’s residence. Our survey results showed that the AD prevalence rate ranged between 26.2% and 35.9%. Children living in polluted areas (near industrial and central urban areas) had about 10% higher prevalence of AD than those living in coastal or suburban areas. The chi-square test demonstrated that this local difference was statistically significant before and after adjustment of major confounder such as parental AD history and education. The results of the logistic regression analysis showed that AD prevalence was significantly associated independently with socio-economic indices and indoor/outdoor environmental factors. The multivariate analysis indicated that statistically significant and robust association between several environmental factors (ventilation status, exposure to diesel exhaust, and outdoor PM10/O3 pollution) and the prevalence of AD was found after adjustment by confounders. The adjusted odd ratios for the AD prevalence were 1.24 (95% CI: 1.03-1.49) and 1.79 (95% CI: 1.17-2.75) with increase in PM10 level of 10 ㎍m-3 and O3 level of 10 ppb, respectively. Although there should be other risk factors for AD, our results suggest that living in polluted area and exposure to high levels of air pollutants can contribute to the increased risk of childhood AD.

Introduction We herein used data from the Korean National Health and Nutritional Examination Survey (KNHANES) 2008–2012 to examine the associations between blood mercury levels and subclinical changes of liver function in a representative sample of the adult Korean population. Methods This study was based on data obtained from KNHANES, in which a rolling sampling design was used to perform a complex, stratified, multistage probability cluster survey of a representative sample of the non-institutionalized civilian population in South Korea. The associations between subclinical hepatic changes and blood mercury levels were assessed after adjustment for various demographic and lifestyle factors. Results Multivariate linear regression analyses revealed that each doubling of blood mercury increased serum aspartate transaminase (AST) by 0.676 U/L and serum alanine transaminase (ALT) by 1.067 U/L. The mean differences (95% CI) in serum AST and ALT between the lowest and highest quartiles were statistically significant at 1.249 (0.263–2.235) U/L and 2.248 (0.648–3.848), respectively. Logistic regression analysis showed that the odd ratios for having serum AST and ALT levels above the median were statistically significant in both the models according to the increase of blood mercury. The risks of having serum AST and ALT levels higher than the median among subjects in 4th quartile of blood mercury were 1.524 and 1.947, respectively. Discussion The present findings show that subclinical changes of liver function are associated with blood mercury levels. This is the first study to show an association between blood mercury levels and mild liver dysfunction, as a possible proxy measure of nonalcoholic fatty liver disease (NAFLD), in Asian population.