Effect of Noise on Sleep and Autonomic Activity in Children according to Source

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.

Effect of Noise on Sleep and Autonomic Activity in Children according to Source

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.

The Prevalence and Incidence of Insomnia in Korea during 2005 to 2013

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<0.001). @*Conclusion@#This large-scale population-based cohort study provided current epidemiologic indicators of insomnia in the Korean general population.

Sleep Assessment During Shift Work in Korean Firefighters: A Cross-Sectional Study

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 < 0.05). Sleep efficiency decreased in night shift and increased in rest day, whereas wake after sleep onset increased in night shift and decreased in rest day (p < 0.05). Among shift work groups, sleep efficiency of 6-day shift was higher in day shift, and sleep efficiency of 21-day shift was lower in night shift than other shift groups (p < 0.05). CONCLUSION: We found that the sleep quality in night shift of the shift work group was poorer than the control group. As to the type of shift work, sleep quality was good in 6-day shift and poor in 21-day shift. Thus, fast rotating shift such as 6-day shift may be recommended to improve the sleep quality of the firefighters.

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.

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.

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.

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 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.

Comparisons of hearing threshold changes in male workers with unilateral conductive hearing loss exposed to workplace noise: a retrospective cohort study for 8 years

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 < 0.05). The threshold change at 4 kHz was 3.2 dBHL higher in SNHL ears which was statistically significant (p < 0.05). When workers were exposed to noise levels of 85 dBA and above, threshold change at 4 kHz was 5.6 dBHL higher in SNHL ears which was statistically significant (p < 0.05). Among workers aged below 50, the threshold change values were lower in low-frequency (0.5–2 kHz) in SNHL ears, with a small range of changes, whereas in high-frequency (3–6 kHz), the range of changes was greater SNHL ears (p < 0.05). Among workers aged 50 and above, SNHL ears showed a wider range of changes in both high- and low-frequency areas (p < 0.05). CONCLUSIONS: At high-frequencies, particularly at 4 kHz, the range of hearing threshold changes was lower in ears with conductive hearing loss than in contralateral ears. This is suggested as a protective effect against noise exposure.

The Effects of Different Noise Types on Heart Rate Variability in Men

PURPOSE: To determine the impact of noise on heart rate variability (HRV) in men, with a focus on the noise type rather than on noise intensity. MATERIALS AND METHODS: Forty college-going male volunteers were enrolled in this study and were randomly divided into four groups according to the type of noise they were exposed to: background, traffic, speech, or mixed (traffic and speech) noise. All groups except the background group (35 dB) were exposed to 45 dB sound pressure levels. We collected data on age, smoking status, alcohol consumption, and disease status from responses to self-reported questionnaires and medical examinations. We also measured HRV parameters and blood pressure levels before and after exposure to noise. The HRV parameters were evaluated while patients remained seated for 5 minutes, and frequency and time domain analyses were then performed. RESULTS: After noise exposure, only the speech noise group showed a reduced low frequency (LF) value, reflecting the activity of both the sympathetic and parasympathetic nervous systems. The low-to-high frequency (LF/HF) ratio, which reflected the activity of the autonomic nervous system (ANS), became more stable, decreasing from 5.21 to 1.37; however, this change was not statistically significant. CONCLUSION: These results indicate that 45 dB(A) of noise, 10 dB(A) higher than background noise, affects the ANS. Additionally, the impact on HRV activity might differ according to the noise quality. Further studies will be required to ascertain the role of noise type.

Nailfold capillary microscopy for evaluating hand-arm vibration syndrome

OBJECTIVES: We evaluated nailfold capillary abnormalities in patients with hand-arm vibration syndrome using nailfold capillary microscopy. METHODS: Fifty workers who underwent a special health examination because of exposure to hand-arm vibration at Ulsan University Hospital in 2012 (exposed group) and a control group of 50 white-collar employees were evaluated through a questionnaire survey regarding their present tasks, types of tools used, vibration exposure duration, use of protective wear, and medical history. Then, an occupational physician performed a physical examination for any hand deformities, skin problems, or motor and sensory dysfunctions of the upper extremities. The nailfold capillary morphologies (tortuous, crossing, bushy, meandering, branching, hemorrhage, avascular area, enlarged, and giant), capillary dimensions (afferent, top, venous, total width, and length), and specific counts (crossing and branching) on both fourth fingers were determined by a rheumatologist. Thereafter, the exposed subjects were assessed according to the Stockholm workshop classification scale. In total, 8 and 6 subjects in the exposed and control groups, respectively, were excluded from the study because of poor capillary microscopic image quality. In addition, 24 subjects in the exposed group with Stockholm vascular stage 0 were excluded. Finally, capillary morphology, dimensions, and specific counting were compared between the exposed (n = 18) and control groups (n = 44). RESULTS: The exposed group had significantly greater crossing capillaries and abnormal capillary numbers that included crossing capillaries (crossing, branching, bushy, and meandering) but smaller branching and abnormal capillary numbers that excluded crossing capillaries (branching, bushy, and meandering) than the control group did. No significant difference in capillary dimensions was observed between the two groups. Despite the adjustment for age, smoking status, and underlying diseases, the statistical significance was unchanged. In the specific counting of the type of capillaries, the exposed group had a significantly higher total crossing count but fewer total branching count than the control group did. However, no statistical significance resulted after adjustment for age, smoking status, and underlying diseases. CONCLUSIONS: In this study, the exposed group had significantly more crossing capillaries and a higher crossing count than the control group did.

Relationship of cigarette smoking and hearing loss in workers exposed to occupational noise

OBJECTIVES: To investigate the effects of smoking on hearing loss among workers exposed to occupational noise. METHODS: From the results of a special workers health examination performed in 2011, we enrolled 8,543 subjects exposed to occupational noise and reviewed the findings. Using self-reported questionnaires and health examination results, we collected data on age, smoking status, disease status, height, weight, and biochemistry and pure tone audiometry findings. We divided the workers into 3 groups according to smoking status (non-smoker, ex-smoker, current smoker). Current smokers (n = 3,593) were divided into 4 groups according to smoking amount (0.05-9.9, 10-19.9, 20-29.9, > or =30 pack-years). We analyzed the data to compare hearing thresholds between smoking statuses using analysis of covariance (ANCOVA) after controlling for confounder effects. RESULTS: According to ANCOVA, the hearing thresholds of current smokers at 2 k, 3 k, and 4 kHz were significantly higher than that of the other groups. Multiple logistic regression for smoking status (reference: non-smokers) showed that the adjusted odds ratios of current smokers were 1.291 (95% confidence interval [CI]: 1.055-1.580), 1.180 (95% CI: 1.007-1.383), 1.295 (95% CI: 1.125-1.491), and 1.321 (95% CI: 1.157-1.507) at 1 k, 2 k, 3 k, and 4 kHz, respectively. Based on smoking amount, the adjusted odds ratios were 1.562 (95% CI: 1.013-2.408) and 1.643 (95% CI: 1.023-2.640) for the 10-19.9 and > or =30 pack-years group, respectively, at 1 kHz (reference: 0.05-9.9 pack-years). At 2 kHz, the adjusted odds ratios were increased statistically significantly with smoking amount for all groups. At all frequencies tested, the hearing thresholds of noise-exposed workers were significantly influenced by current smoking, in particular, the increase of hearing loss at low frequencies according to smoking amount was more prevalent. CONCLUSIONS: Current smoking significantly influenced hearing loss at all frequencies in workers exposed to occupational noise, and heavier smoking influenced low-frequency hearing loss more greatly. There was a dose-response relationship between smoking amount and low-frequency hearing thresholds; however, this was not observed for high-frequency hearing thresholds. Therefore, well-designed prospective studies are needed to clarify the effects of smoking on the degree of hearing loss.

The Characteristics of Tinnitus and Hearing Threshold: In Workers with Noise Induced Hearing Loss from a Hospital Setting / 대한산업의학회지

OBJECTIVES: This study was carried out to define the relationship between the characteristics of tinnitus and hearing threshold (puretone and speech) in workers with noise induced hearing loss (NIHL). METHODS: A total of 189 cases(378 ears) from workers with compensation claims for NIHL during 2004-2009 were investigated. Various factors, including age, work carriers, body mass index (BMI), blood pressure, noise exposure level of worksite hearing threshold, speech discrimination score, pitch match, and loudness of tinnitus were analyzed. RESULTS: The average hearing threshold of all subject was 44.2 dBHL, puretone audiometry thresholds in subjects with tinnitus were lower than the non-tinnitus group (except at 8000 Hz). Using speech audiometry, the tinnitus group showed a lower speech recognition threshold and speech discrimination score. The tinnitus group also had an average tinnitus frequency of 4195.2 Hz, loudness of 73.6 dB, and tinnitus sensation average of 6.0 dBSL. These frequencies of tinnitus were in the lowest puretone audiometry frequencies. Tinnitus loudness had a strong relationship with puretone and speech audiometry thresholds. CONCLUSIONS: In cases beyond moderate hearing loss, the tinnitus group had a better puretone (except 8000 Hz) and speech hearing status, and most comfortable loudness (MCL) level. In addition, puretone and speech audiometry thresholds increase with tinnitus loudness.

The General Characteristics and Results of the Cold Provocation Test in the Risk Group of HAVS / 대한산업의학회지

OBJECTIVES: The cold provocation test for diagnosing the vascular component in hand-arm vibration syndrome (HAVS) is likely to be accepted as an objective test, and a few studies have been performed. However, controversy has continued regarding the diagnostic performance of this method. Although objective methods such as plethysmography and laser doppler flowmetry have been studied, they have not received as much attention as other diagnostic methods. Therefore, our study aim was to spread the awareness of HAVS by reporting the results of the cold provocation test in a hand-transmitted vibration exposure group. METHODS: The study subjects were 549 workers who had been exposed to hand-transmitted vibrations and reported symptoms in their hands. While the subject immersed both their hands in 10degrees C water for 10 minutes, the skin temperature of 10 fingers was recorded from pre-immersion time to 20 minute postimmersion including 10 minutes immersion time. The recovery rates were calculated from the recorded skin temperatures. The 'decreased recovery rate' criteria were less than 30% at 5 minutes post-immersion and 60% at 10 minute post-immersion. RESULTS: Of the subjects, 69.1% and 30.9% had more severe symptoms in the right and left hands, respectively. The mean finger skin temperature of the right hand after cold-water immersion for 10 minutes was approximately 10degrees C, which increased gradually with time, but they did not reach the baseline temperature at 20 minutes post-immersion. The deviations of the skin temperature in the subjects were higher in the recovery phase than in the baseline and cold immersion phase. The 3rd finger of both hands showed the lowest 5-minute recovery rate among the fingers examined, and the left 4th finger and right 3rd finger showed the lowest 10-minute recovery rate. Of the subjects, 37.6% and 10.4% of subjects showed a lower recovery rate at 5 and 10 minutes in at least one finger, respectively, while 10.2% showed a lower recovery rate at both 5 and 10 minutes simultaneously in at least one finger. CONCLUSIONS: The larger deviations in the recovery phase than in the other phases indicated that interindividual differences are more prominent in the recovery phase. There might be no benefit in observing the finger skin temperature for an additional 10 minutes after 10 minutes post-immersion. Overall, approximately 10% of the subjects in the HAVS risk group had HAVS.

Differences in Sleep Patterns are Related to Behavior, Emotional Problems, Attention and Academic Performance in Elementary School Students of a South Korean Metropolitan City

OBJECTIVES: 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 demonstrated 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 that the reduced sleep duration and disruption of sleep pattern can have a significant impact on emotion, behavior, performance of learning in children. Further studies concerning more diverse psychosocial factors affecting sleep pattern will be helpful to understanding of the sleep health in Korean children.

Clinical Characteristics of Primary Headache According to Age in Children and Adolescents / 대한소아신경학회지

PURPOSE: Childhood headache is different from adulthood headache and according to their age in clinical aspects. This study investigated the clinical differences of primary headache according to ages of children and adolescents. METHODS: A 300 children who did not show abnormalities on neurologic examination or brain CT or MRI were classified into two groups according to their ages. RESULTS: The percentage of those in the migraine group (24.2% vs. 35.9% in Groups 1 and 2 respectively) was higher in Group 2, but it was not statistically significant. In relation to the duration of headache, pain lasting for less than one hour accounted for 59.8% and 40% in Groups 1 and 2, respectively (P=0.001). In relation to the location headaches developed, the frontal region (40.2%) and temporal region (48.1%) were the most common in Groups 1 and 2, respectively (P<0.001). In relation to the nature of the headaches, tightening sensation accounted for the highest percentage in both groups; however, pulsating sensation were more common in Group 2 than in Group 1 (16.2% vs. 8.3%, P=0.038). In relation to the severity of headaches, severe to profound headaches accounted for 35.5% and 61.1% in Groups 1 and 2, respectively (P<0.001). In relation to laterality, unilateral headaches accounted for 12.4% and 26.7% in Groups 1 and 2, respectively (P=0.002). In relation to accompanying symptoms, the incidence of photophobia was higher in Group 2 than in Group 1 (P=0.047). CONCLUSION: Age factors should be considered in the diagnosis of childhood headaches. Also, we consider that there may be a need to establish diagnostic criteria specifically for childhood headaches separately from those for adulthood headaches.

Seroprevalence of Hepatitis A in a Manufacture Workplace / 대한산업의학회지

OBJECTIVES: The prevalence of hepatitis A decreases with improved hygiene and changing lifestyle. However, hepatitis A remains a global problem causing sporadic food-borne infections. Over the past 5 years, hepatitis A incidence has increased, and 15 deaths were reported in 2009 in Korea. Concerns about hepatitis A infection have increased. We checked hepatitis A virus antibody (HAV anti-IgG) in a large manufacturing company, so that the results could be a guideline for workplace preventive plan and health policy for hepatitis A. METHODS: We investigated the seroprevalence of HAV anti-IgG and the demographic characteristics of employee volunteer, in a company in Ulsan. In addition, we estimated those factors that affected seroprevalence of HAV anti-IgG. RESULTS: A total of 2,719 employee volunteers were enrolled into the study. The seropositive rate of HAV anti-IgG was 69.8% (n=1,899) and, the seronegative rate was 30.2% (n=820). There were no enrolled employees under age 24 years who tested positive for HAV anti-IgG; in this group, the seropositive rate was 0.0% (n=0); in 25~29 years the rate was 3.9% (n=12) and 26.5% (n=118) in 30~34 years olds. In the 35-39 ears, 61.1% (n=203) tested HAV anti-IgG positive and 86.8% (n=256) of 40~44 years tested positive. Other group tested as follows: 96.5% (n=335) in 45~49 year olds, 98.7% (n=593) in 50~54 year olds, and 100% (n=382) in over 55 years. There was a significantly increasing tendency to test HAV anti-IgG positive according to age group. In the 34-35 year olds, the seropositive rate exceeded the seronegative rate. CONCLUSIONS: HAV anti-IgG seropositive rate increased according to age. The result can used for guideline recommendationsand establishing hepatitis A policies.

Effects of Workplace Noise and Hearing Protective Devices on Worker's Speech Intelligibility / 대한산업의학회지

OBJECTIVE: The objective of this study was to evaluate the degree of intelligible speech in workers wearing hearing protective devices and the differences in background noise type. METHODS: A total 82 shipyard company employees and normal hearing volunteers were recruited as subjects from a company in Ulsan: subjects were classified to the hearing-impaired group or to the control group according to hearing status. They were tested pure tone and speech audiometry in varying test environments including signal-to-noise ratio and background noise type in a headphone and in a free field environment. RESULTS: For both groups, the attenuation of hearing protective devices was greater at high frequencies. For the hearing-impaired group, speech discrimination scores differences between the unprotected and the protected ear were not significant between background noise type, when speech was presented at 65 dBA. However speech intelligibility in white noise background was lower than in the other background noise types when speech was presented at 75 dBA. CONCLUSIONS: Workers' speech intelligibility increased with an increasing signal-to-noise ratio. Speech intelligibility was also dependent on background noise type. Workers and their colleagues were trained to pronounce words more loudly and more clearly when they wearing hearing protective devices or other communication methods that do not use sound signal should be considered.