Exposure characteristics of familial cases of lung injury associated with the use of humidifier disinfectants.

BACKGROUND: This study describes 17 families with 38 lung injury patients (14 males, 24 females; 22 preschool-age children less than six years of age and 16 individuals of 13-50 years) who used disinfectant added to humidifiers in the home. METHODS: Clinical examination and humidifier disinfectant-use histories were taken, and a thorough home investigation was performed to assess exposure to humidifier disinfectant. RESULTS: Nine of the patients (three pregnant females, six preschool-age children) died soon after they first developed lung damage. Six (16%) were pregnant females and 22 (58%) were preschool-aged children younger than six years. The patients used humidifier disinfectant products containing either polyhexamethylene guanidine phosphate (PHMG, n = 36) or oligo(2-(2-ethoxy)ethoxyethyl guanidinium chloride (PGH, n = 2). Twenty-six patients (68%) used the brand "Oxy"®, which contains PHMG. Of the ten patients with fatal lung injury, nine were found to have used PHMG. CONCLUSIONS: Our findings suggest that the use of humidifier disinfectant products containing either PGH or PHMG can cause lung injury, especially in preschool-age children younger than six years and pregnant women.

Smoking induced heavy metals and periodontitis: findings from the Korea National Health and Nutrition Examination Surveys 2008-2010.

AIM: Exposure to hazardous heavy metals such as cadmium and lead may contribute to increased oxidative stress and inflammation in the periodontal tissue. We aimed to evaluate the association between serum cadmium and lead levels and periodontitis. MATERIALS & METHODS: Pooled cross-sectional data from the Korea National Health and Nutrition Examination Surveys 2008-2010 were used. Periodontitis was defined as WHO community periodontal index. Active smokers were defined as self-reported current smokers or those with measured urine cotinine ≥164 ng/ml measurements. Serum cadmium and lead levels were measured using graphite furnace atomic absorption spectrometry. Multiple logistic regression analysis was used to estimate the odds ratios (OR) for periodontitis. RESULTS: The mean cadmium and lead levels were significantly higher in the periodontitis group compared with control population. A progressive increase in serum heavy metals were found as the number of sextants with periodontitis. The ORs for periodontitis were significantly associated with serum cadmium (OR = 1.37; 95% CI 1.00-1.87) and lead levels (OR = 1.60; 95% CI 1.15-2.21). The association between periodontitis and smoking was attenuated after adjusting for serum cadmium concentration. CONCLUSIONS: We demonstrated a significant association between periodontitis and serum cadmium and lead concentrations. Cadmium appeared to partially mediate the association between smoking and periodontitis.

Trades of dangers: a study of asbestos industry transfer cases in Asia.

BACKGROUND: In a study of asbestos industry transfers in Asia, we examined the transfer of health and safety measures at the time of industry transfer and resulting health outcomes thereafter. METHODS: Field surveys were conducted in Japan, Germany, Indonesia, and South Korea over a 5 year period beginning in 2007. The surveys involved interviews and field assessments of health and safety conditions. RESULTS: Even when there were transfers of entire engineering plant processes, we observed that the health and safety measures that should have accompanied the transfer, including technical capacities of risk assessment and management, regulatory protection, and cultural practices, were not actually transferred. According to work environment assessment records, there were differences in airborne asbestos levels of approximately 5-6 fibers/cc between the exporting and importing sides of the transfer. This amounted to a 10 years of time delay in comparable health and safety conditions. These differences resulted in repeated adverse health consequences at each factory operation site. CONCLUSIONS: Dangerous transfers of asbestos industry technology have occurred repeatedly over the years with the result that Asia has become the largest consumer of asbestos in the world. No effective internationally accepted safety measures have been introduced in the region. The study results support the need for both improved public awareness and international cooperation, such as sharing of substitute material technologies by the exporting countries, and provide the rationale for the creation of an Asian fund for asbestos victims.

Why some, but not all, countries have banned asbestos.

BACKGROUND: Out of 143 countries that consumed asbestos between 2003 and 2007, only 44 have banned asbestos. This study tried to explain why some countries have banned asbestos while others have not, based on a synthesis that asbestos ban policy of a country will rely on a process of cognition of threats and exploration of safer alternatives. METHOD: As we hypothesized that increased social cost of mesothelioma, capacity of health-related infrastructures, and policy diffusion from adjacent countries were related to asbestos ban adoption, published databases of asbestos ban years, mesothelioma mortality, country rankings in health care and human rights standings, and distribution of banning countries over 14 regions were analyzed accordingly. RESULTS: The average mesothelioma death rate was significantly higher for countries with asbestos bans than in those with no ban (4·59 versus 1·83/million). No-ban countries had less well-developed health-related infrastructures. Among European countries, there was a tendency toward geographical diffusion of asbestos ban policy from Nordic to Western and then other European countries over the years. Even though aberrant cases were also noted where bans were instituted even without mesothelioma database, these were rather exceptions than rules. CONCLUSION: Risk cognition is a complex process, but the presence of well-functioning health infrastructures, as well as the increased social cost of mesothelioma, that can make the plight of asbestos victims visible to the eyes of public and policy makers, may have contributed to this process. Asbestos ban policy from adjacent countries might have facilitated the adoption of alternative solutions.

Periodontitis could be related factors on metabolic syndrome among Koreans: a case-control study.

AIM: Several studies have suggested that metabolic disorders are related to periodontitis. The objective of this study is to assess whether periodontitis is associated with the metabolic syndrome (MetS) among Koreans. MATERIAL AND METHODS: This case-control study was performed among 167 cases with MetS and 166 healthy controls from Shiwha-Banwol Environmental Health Cohort (N = 1853). The community periodontal index (CPI) was used to assess periodontitis (CPI 3-4). MetS was an outcome variable and periodontitis was a main explanatory variable. Age-gender-matched conditional logistic regression models were applied. Monthly household income, smoking, drinking, physical activity and diabetes mellitus were factored as confounders. We also performed stratified analyses according to confounders. RESULTS: Those with periodontitis are more likely to be patients with MetS than those without periodontitis. The adjusted odds ratio of periodontitis for MetS was 1.76. There was no significant dose-effect response on the relationship between the number of sextants with periodontitis and MetS. Links became higher in adults aged 45-60 years and adults without diabetes mellitus. CONCLUSIONS: These results suggest that periodontitis could be an independently related factor on MetS. Hence, dentists and physicians should be aware of the importance of periodontitis as a potential source of inflammatory burden.

The Unequal Burden of Self-Reported Musculoskeletal Pains Among South Korean and European Employees Based on Age, Gender, and Employment Status.

BACKGROUND: The objective of this study was to elucidate the relationships musculoskeletal pains with combined vulnerability in terms of age, gender, and employment status. METHODS: The fifth European Working Conditions Survey (EWCS) in 2010 (43,816 participants aged 15 years and over) analyzed for European employees and the third Korean Working Conditions Survey (KWCS) in 2011 (50,032 participants aged 15 years and older) analyzed for Korean employees. In this study, three well known vulnerable factors to musculoskeletal pains (older age, female gender, and precarious employment status) were combined and defined as combined vulnerability. Associations of musculoskeletal pains with combined vulnerability were assessed with prevalence ratios (PRs) and 95% confidence intervals (CIs) estimated by Poisson regression models with robust estimates of variance. RESULTS: The prevalences of musculoskeletal pains were lower but the absolute and relative differences between combined vulnerabilities were higher among Korean employees compared with the European employees. Furthermore, the increased risk of having musculoskeletal pains according to combined vulnerability was modestly explained by socioeconomic factors and exposure to ergonomic risk factors, especially in Republic of Korea. CONCLUSIONS: The results of this study showed that the labor market may be more unfavorable for female and elderly workers in Republic of Korea. Any prevention strategies to ward off musculoskeletal pains, therefore, should be found and implemented to mitigate or buffer against the most vulnerable work population, older, female, and precarious employment status, in Republic of Korea.

The association of metabolic syndrome with periodontal disease is confounded by age and smoking in a Korean population: the Shiwha-Banwol Environmental Health Study.

AIM: Because metabolic syndrome (MS) is pro-inflammatory and periodontitis is inflammatory, we issued the hypothesis that MS (the explanatory variable) is associated with periodontitis (the outcome variable). This study aimed to examine the link between MS and periodontitis among Koreans. MATERIALS AND METHODS: From the Shiwha-Banwol Environmental Health Study, 1046 subjects aged 18 years or older were cross-sectionally surveyed. All participants underwent comprehensive dental and medical health examinations. The community periodontal index was used to assess periodontitis. Age, gender, monthly family income, smoking, drinking, frequency of daily teeth brushing, and physical activity were evaluated as confounders. RESULTS: MS was strongly associated with periodontitis [odds ratio (OR): 1.7, 95% confidence interval (CI): 1.22-2.37], and MS with more components had a higher association. The association was higher for elders aged 65 years or more, males, and smokers. MS including both high glucose and hypertension had a higher association with the OR of 2.19 (95% CI: 1.23-3.90) comparing with other types of MS. CONCLUSIONS: Our results suggested that MS might be associated with periodontitis and the association was confounded by age, gender, and smoking. MS with high glucose and hypertension showed the higher impact on this link.

Visceral fat area-defined obesity and periodontitis among Koreans.

AIM: Although the association of periodontitis with body mass index (BMI)-defined obesity has been studied, it remains controversial. Hence, this study aims to determine whether the obesity is associated with periodontitis among Koreans and to determine the most significant indicator of the obesity on the link. MATERIALS AND METHODS: From the Sihwa-Banwol Environmental Health Cohort, 1046 subjects 15 years of age or older were cross-sectionally surveyed. All participants underwent periodontal and medical health examinations. Age, gender, monthly family income, smoking, drinking, frequency of daily teeth brushing and physical activity were evaluated through interviews. The community periodontal index (CPI) was used to assess periodontitis. BMI, waist circumference (WC), waist hip ratio and visceral fat area (VFA) were used to assess obesity. Multivariate linear and logistic regression analyses were applied. RESULTS: BMI, WC and VFA had a dose-effect relationship with the number of sextants with periodontitis. Although subgroup analysis revealed several significant associations between obesity and periodontitis (CPI 3-4), the greatest association between VFA and periodontitis was found in males, age 45-54 (odds ratio=3.30; 95% confidence interval: 1.53-7.09). CONCLUSIONS: Obesity was associated with periodontitis. VFA was the most suitable indicator of obesity in relation to periodontitis. Obesity may be a substantial risk factor for periodontitis.

The associations between personal care products use and urinary concentrations of phthalates, parabens, and triclosan in various age groups: The Korean National Environmental Health Survey Cycle 3 2015-2017.

Phthalates and parabens are ubiquitous chemicals of public concern. This study aimed to investigate the use of personal care products (PCPs) as predictors of exposure to phthalates, parabens, and triclosan (TCS) among various age groups in a nationally representative population. The concentrations of eight phthalate metabolites, three parabens, and TCS were measured in a random spot urine sample in 5962 study participants (age range: 3-86 years). The information on PCPs use was obtained in seven categories over previous three months. The exposure risks to phthalates, parabens, and TCS were different according to the pattern of PCPs use in different age groups and gender. In adolescents and adults, females used all categories of PCPs more frequently than males, with statistical significance. The use rates of PCPs and the significant exposure risks to phthalates, parabens, and TCS associated with PCP use were more clearly observed in adults. The least square geometric means (LSGMs) of urinary methylparaben (MeP), ethylparaben (EtP), and propylparaben (PrP) steadily increased, as the cumulative number of used PCPs increased with statistical significance. The exposure risks to MeP were consistently observed with various PCPs use and showed a significant increase as the cumulative number of PCPs use increased in adults. Furthermore, the use of fragrance products, makeup, and air fresheners significantly increased the exposure risk to EtP in preschoolers. The significant exposure risk to mono-(3-carboxypropyl)- phthalate (MCPP) associated with nail polishes use was observed in preschoolers and adults. This study showed the associations between PCPs use and urinary concentrations of phthalates, parabens, and TCS in various age groups. Environmental health policies to reduce exposure to phthalates and parabens should be widely implemented, including industry regulations and increasing public awareness. Future studies are needed to explore other important exposure sources of these chemicals and their related adverse health effects.

Exposure to environmental pollutants and a marker of early kidney injury in the general population: Results of a nationally representative cross-sectional study based on the Korean National Environmental Health Survey (KoNEHS) 2012-2014.

Exposure to environmental pollutants may lead to early kidney injury, chronic kidney disease (CKD) and end-stage renal disease (ESRD). This study investigated the early renal effects associated with exposure to endocrine-disrupting chemicals (EDCs) and heavy metals using general Korean population data. We used data from the Second Korean National Environmental Health Survey (2012-2014). As exposure markers, the concentrations of EDCs, such as triclosan (TCS), bisphenol A (BPA) and phthalate metabolites (DEHP, MnBP and MBzP), and heavy metals, such as cadmium, lead and mercury were analyzed. As an early kidney injury marker, the urinary concentration of ß2-microglobulin (ß2M) was measured. Multiple linear regression was used to analyze the relationship between environmental pollutants and ß2M. A total of 5489 people (male: 2538, female: 2951) aged 19 years and older were enrolled. The geometric mean (GM) concentration of ß2M in the total population was 1.88 µg/g creatinine (95% confidence interval (CI) 1.85-1.91). The ß2M concentrations were significantly higher in cases of female, old age, low income, and presence of a history of diabetes mellitus or hypertension. The GM concentrations of urinary TCS and cadmium were 1.16 µg/g creatinine (95% CI 1.11-1.21) and 0.57 µg/g creatinine (95% CI 0.57-0.59), respectively. TCS, DEHP, cadmium, lead, and mercury exposure was significantly positively related to urinary ß2M in the multiple regression analysis. ß2M levels increased significantly with increases in the cadmium, mercury, and lead levels (p for trend <0.0001). The higher the DEHP, MnBP, and TCS concentrations, the higher the ß2M level (p for trend <0.01). Environmental pollutants exposure significantly increased urinary ß2M levels in the general Korean population. To prevent the development of early kidney injury and CKD, it is important to reduce environmental pollutants exposure through regulatory measures, and cooperation between related bodies in both developing and developed countries.

Relationship between personal care products usage and triclosan exposure: the second Korean National Environmental Health Survey (KoNEHS 2012-2014).

BACKGROUND: We aimed to find the exposure level of triclosan (TCS), a known endocrine disruptor, related to the use of personal care products using a nationally representative data of the general population in Korea. METHODS: This study included data of 6288 adults aged 19 years and older (2692 men, 3596 women), based on the Second Korean National Environmental Health Survey (KoNEHS 2012-2014). The data were divided according to gender. The frequency and proportion of each variable were determined by dividing participants into two groups based on the top 75th percentile concentration of urinary TCS (male: 1.096 µg/g creatinine, female: 1.329 µg/g creatinine). Odds ratios (ORs) were calculated using logistic regression analysis for the high TCS exposure and low TCS exposure groups. RESULTS: Overall, the proportion of participants using personal care products was higher in women than in men. There was a significantly higher proportion of participants in the high TCS exposure group with younger age, higher education and income levels and with more frequent use of fragrance products, hair care products, body cleansers, cosmetics, and antimicrobial agents. In both men and women, ORs tended to increase with increased frequency of use of hair care products, body cleansers, and cosmetics before and after adjustment. CONCLUSIONS: Our findings demonstrate that as the frequency of use of personal care products increases, urine TCS concentration increases. Because TCS is a well-known endocrine disruptor, further studies are needed and explore other health effects with exposure to TCS in general population in Korea.

Combined exposure of emotional labor and job insecurity on depressive symptoms among female call-center workers: A cross-sectional study.

Call-center workers work under unfavorable psychosocial working conditions, including, emotional labor and job insecurity, which might be linked to depressive symptoms.The purpose of this study was to explore the link between emotional labor and depressive symptoms and to investigate the influence of combined exposure to emotional labor and job insecurity on depressive symptoms.A health survey was conducted among female call-center workers in Geumcheon-gu (a district in Seoul), South Korea, in November 2012. The short form of the Korean occupational stress scale was used to measure occupational stressors. A questionnaire with 8 items was employed to assess emotional labor. Depressive symptoms were estimated using the Korean Version of the Centre for Epidemiologic Studies Depression Scale (CES-D). The association of emotional labor and occupational stressors with depressive symptoms was assessed using multilevel mixed-effects logistic regression.Overall, 699 female call-center workers were enrolled into this study. The odds ratios of experiencing depressive symptoms in workers exposed to emotional labor and job insecurity were 5.45 (95% confidence interval [CI]: 3.38-8.80) and 2.37 (95% CI: 0.86-6.50), respectively. When workers were simultaneously exposed to excessive emotional labor and high job insecurity levels, the odds ratio of experiencing depressive symptoms was 10.13 (95% CI: 3.51-29.23). The Relative Excess Risk due to the Interaction (RERI) of job insecurity and emotional labor was 3.30 (95% CI: -5.50 to 12.11); however, this was not statistically significant (P = .46).Although a causal relationship could not be established due to the cross-sectional study design, the combined effect of emotional labor and job insecurity might have a serious influence on behavioral health among call-center female workers.

Female non-smokers' environmental tobacco smoking exposure by public transportation mode.

BACKGROUND: This study aimed to analyze environmental tobacco smoking exposure in female nonsmokers by public transportation mode using representative data of Koreans. METHODS: Data from the Second Korean National Environmental Health Survey (2012-2014) were analyzed. Urine cotinine was analyzed by public transport behavior, secondhand smoke exposure, socioeconomic factors, and health-related factors. Participants were 1322 adult females; those with the top 75% urine cotinine concentrations were assigned to the high exposure group. A logistic regression analysis was performed considering appropriate weights and stratification according to the sample design of the Second Korean National Environmental Health Survey. RESULTS: The geometric mean of urine cotinine concentrations differed according to public transportation modes: subway (1.66 µg/g creatinine) bus (1.77 µg/g creatinine), and taxi (1.94 µg/g creatinine). The odds ratio [OR] was calculated for the high exposure group. The OR of the taxi (2.39; 95% confidence interval, 1.00-5.69) was statistically significantly higher than the subway value (reference), and marginally significant after adjusted with life style, sociodemographic factors and involuntary smoking frequency (2.42, 95% confidence interval, 0.97-6.04). CONCLUSIONS: The odds ratio of passengers who mainly used taxis was marginally significantly higher than those of passengers who used subways and buses after adjusted with life style and sociodemographic factors. Implementation of supplementary measures and further studies on exposure to environmental tobacco smoking in taxis are warranted.

Effects of polymer-coated boron nitrides with increased hemorheological compatibility on human erythrocytes and blood coagulation.

BACKGROUND: Boron nitride (BN) nanomaterials are promising in biomedical research owing to their large surface area, graphene-like structure, and chemical and thermal properties. However, the toxicological effects of BN on erythrocytes and blood coagulation remain uninvestigated. OBJECTIVE: The aims of our study were to synthesize glycol chitosan (GC)- and hyaluronic acid (HA)-coated BNs, and to investigate the effects of these BNs on human cancer cells, erythrocytes, and whole blood. METHODS: We prepared hemocompatible forms of BN coated with GC and HA, and evaluated them using cell uptake/viability tests, hemolysis analysis and FE-SEM, as well as through hemorheological evaluation methods such as RBC deformability and aggregation, and blood coagulation. RESULTS: GC/BN and HA/BN were both ∼200 nm, were successfully taken into cells, and emitted blue fluorescence. Both BNs were less toxic than bare BN, even at higher concentrations. The aggregation index of human red blood cells (RBCs) after 2 h incubation with BN, GC/BN, and HA/BN was greatly influenced, whereas RBC deformability did not dramatically change. CONCLUSIONS: We found that GC/BN affected the intrinsic coagulation pathway, whereas both GC/BN and HA/BN affected the extrinsic pathway. Therefore, HA/BN is less detrimental to RBCs and blood coagulation dynamics than bare BN and GC/BN.

Relationship between dietary factors and bisphenol a exposure: the second Korean National Environmental Health Survey (KoNEHS 2012-2014).

BACKGROUND: This study was aimed at finding out the exposure level of bisphenol A (BPA), a well-known endocrine disruptor, in relation to dietary factors using a data representing the Korean general population. METHODS: This study was performed on 5402 adults aged 19 years and older based on the Second Korean National Environmental Health Survey (KoNEHS 2012-2014). The data analyzed urinary BPA concentration in relation to socio-demographic variables, health behavior-related variables, and dietary factor-related variables. Odds ratio (OR) was calculated through a logistic regression analysis after dividing the participants into high BPA exposure group and low BPA exposure group based on the top 75 percentile concentration. The logistic regression analysis was carried out considering the appropriate sample weight, stratification, and clustering of the second KoNEHS sample design. RESULTS: The group drinking bottled water at home and the group using zip-top bags/plastic bags showed significantly higher urinary BPA concentration in female. OR tends to increase as the intake frequency of frozen food increased and OR of frozen food consumption of more than once a week was 1.48 (95% confidence interval (CI) 1.02-2.24) for male and the group drinking bottled water showed significantly higher OR of 1.45 (95% CI 1.06-2.17) after adjusting the related factors for female. CONCLUSIONS: BPA levels were high in female using bottled water and in male consuming frozen food, and therefore bottled water and frozen food need to be avoided to reduce BPA levels.

The relationship between spontaneous abortion and female workers in the semiconductor industry.

BACKGROUND: This study investigated the relationship between job type and the risk for spontaneous abortion to assess the reproductive toxicity of female workers in the semiconductor industry. METHODS: A questionnaire survey was administered to current female workers of two semiconductor manufacturing plants in Korea. We included female workers who became pregnant at least 6 months after the start of their employment with the company. The pregnancy outcomes of 2,242 female workers who experienced 4,037 pregnancies were investigated. Personnel records were used to assign the subjects to one of three groups: fabrication process workers, packaging process workers, and clerical workers. To adjust for within-person correlations between pregnancies, a generalized estimating equation was used. The logistic regression analysis was limited to the first pregnancy after joining the company to satisfy the assumption of independence among pregnancies. Moreover, we stratified the analysis by time period (pregnancy in the years prior to 2008 vs. after 2009) to reflect differences in occupational exposure based on semiconductor production periods. RESULTS: The risk for spontaneous abortion in female semiconductor workers was not significantly higher for fabrication and packaging process workers than for clerical workers. However, when we stratified by time period, the odds ratio for spontaneous abortion was significantly higher for packaging process workers who became pregnant prior to 2008 when compared with clerical workers (odds ratio: 2.21; 95% confidence interval: 1.01-4.81). CONCLUSIONS: When examining the pregnancies of female semiconductor workers that occurred prior to 2008, packaging process workers showed a significantly higher risk for spontaneous abortions than did clerical workers. The two semiconductor production periods in our study (prior to 2008 vs. after 2009) had different automated processes, chemical exposure levels, and working environments. Thus, the conditions prior to 2008 may have increased the risk for spontaneous abortions in packaging process workers in the semiconductor industry.

Environmental Tobacco Smoke Exposure at Home and High-Sensitivity C-Reactive Protein Levels in Three-to-Five-Year-Old Children.

Exposure to harmful environmental factors is particularly detrimental to younger children. We investigated the relationship between environmental tobacco smoke (ETS) exposure in pre-schoolers at home and the level of high-sensitivity C-reactive protein (hs-CRP), a predictive factor for cardiovascular disease. This study was conducted in 2014 and was based on the data of preschool children from the Korean Environmental Health Survey in Children and Adolescents (2012 to 2014), a nationally representative sample. Of 577 children, aged three to five years, 482 were eventually selected for the analysis after excluding those with missing variables, or whose hs-CRP level exceeded the reference value. The proportion of pre-school children exposed to ETS at home was 14.8%. The odd ratios (OR)s of hs-CRP > 1mg/L were 4.90 (95% Confidence Interval (CI) = 1.04-23.17) and 11.66 (95% CI = 1.90-71.65) in the groups exposed to ETS 3-4 times and ≥5 times daily, respectively, compared to the non-exposed group. The risk of elevated levels of hs-CRP showed an increasing trend proportionally to the increase in ETS exposure frequency (p for trend = 0.03). Anti-smoking educational programs for parents and guardians may be helpful to reduce ETS exposure at home.

The association between long working hours and hearing impairment in noise unexposed workers: data from the 5th Korea National Health and Nutrition Examination Survey (KNHANES 2010-2012).

BACKGROUND: This study is aimed at finding out the relationship between long working hours, one of major job stress elements, and hearing impairment in unexposed workers to occupational and environmental noise. METHODS: This study was performed on 1628 regular, full-time wage workers between the age of 25-64 who indicated in the survey of having no experience of exposure to noise, normal otoscopic findings, and not suffering from diabetes based on the data from the fifth Korea National Health and Nutrition Examination Survey (KNHANES 2010-2012). The average working hours per week was categorized into 40 h and lower group, more than 40 to 48 h group, more than 48 to 60 h group, and more than 60 h group. The groups were defined as suffering from low or high frequencies hearing impairment if the average hearing threshold for 0.5, 1, 2 kHz or 3, 4, 6 kHz in both ears exceeds 25 dB based on the pure tone audiometry. The association between average weekly working hours and hearing impairment was analyzed using logistic regression after gender stratification. RESULTS: The prevalences of low and high frequencies hearing impairment in male workers were 4.3 and 28.6 %, respectively, which were much higher than female's prevalence of 2.7 and 11.1 %. For male workers, no significant association was found between average weekly working hours and low and high frequencies hearing impairment. For female workers, odds ratios (OR) of low and high frequencies hearing impairment were 4.22 (95 % confidence interval (CI) 1.09-16.27) and 4.49 (95 % CI 1.73-11.67), respectively, after controlling for several related factors, such as, age, Body Mass Index (BMI), socio-economic status, health-related behavioral, and occupational characteristics variables, in the final model in the group working more than 60 h compared to the group working 40 h and lower. In addition, a dose-response relationship was observed that ORs of low and high frequencies hearing impairment were increased according to increasing average weekly working hours. CONCLUSIONS: The association between long working hours and hearing impairment in both low and high frequencies was significant in Korean female workers with a dose-response relationship. Therefore, the law to change the culture of long working hours should be enacted in order to protect the workers' health and improve the quality of life in Korean workers.

The relationship between night work and involuntary weight change: data from the fifth Korea National Health and Nutrition Examination Survey (KNHANES 2010-2012).

BACKGROUND: Previous studies on the association between shift or night work and weight change have been focused on finding the risk of weight gain caused by shift or night work. In this study, we aimed to reveal the risk of weight gain and weight loss associated with night work by using a nationwide representative data. METHODS: This study was performed on 1605 full-time wage workers between the age of 20 and 69 based on the fifth Korea National Health and Nutrition Examination Survey (KNHANES 2010-2012). The association between night work and involuntary weight change in the previous year was divided into the categories of weight gain and weight loss and studied with modifications in socio-demographic variables, health behavior-related variables, and occupational characteristic variables. RESULTS: The participants working in night work accounted for 10.6 % of total study participants (male; 11.9 %, female 7.4 %). Workers who worked more than 48 hours per week on average accounted for 41.6 % of the total study participants (male; 46.3 %, female 29.1 %). Odds ratio (OR) of weight loss associated with night work in male workers was 0.34 (95 % confidence interval (CI) 0.16-0.76) after controlling for several related factors. OR of weight loss associated with night work in female workers with long working hours was 1.95 (95 % CI 0.47-80.86) and that of weight gain was 2.83 (95 % CI 0.12-69.83) after adjusting associated factors. CONCLUSIONS: In this cross-sectional study with national representative sample, night work may lower the risk of weight loss in male workers and induce weight change (weight loss or weight gain) in female workers with long working hours. Therefore, future studies with cohort study design for night workers are needed to reveal the mechanisms and health effects of weight change associated with night work and establish proper management solutions with health and labor policies for Korean night workers.