Association between temporary employment and current smoking and change in smoking behaviors: A prospective cohort study from South Korea (2009-2018).

Background Previous studies have suggested that employment insecurity is associated with adverse health outcomes. We explored the association between temporary employment and smoking behaviors.Methods We analyzed 11,795 workers (51,867 observations) from the Korea Health Panel Study (2009-2018). Employment types were categorized as regular, fixed-term, or daily, based on the duration of labor contract. The outcomes were current smoking status and changes in smoking behavior (initiation or cessation) in the following year. Generalized estimating equations were used to estimate odds ratio (OR) and 95% confidence interval (CI).Results The proportions of fixed-term and daily workers were 41.2% and 16.4% for women and 23.6% and 12.4% for men, respectively. Temporary employment was associated with increased odds of current smoking, while also demonstrating prospective associations with changes in smoking behaviors. For instance, in prospective analyses, male workers with fixed-term and daily employments were associated with a decreased likelihood of smoking cessation (OR:0.77; 95% CI:0.65-0.91 for fixed-term employment and OR:0.66; 95% CI:0.52-0.83 for daily employment) in the following year compared to those with regular employment. Moreover, those experiencing consecutive temporary employment was most inversely associated with smoking cessation in both men (OR:0.56; 95% CI:0.44-0.71) and women (OR:0.37; 95% CI:0.16-0.85) compared to those experiencing consecutive regular employment. However, no clear association between temporary employment and smoking initiation was observed in both men and women.Conclusions Temporary employment is directly associated with current smoking and inversely associated with smoking cessation. Policies are needed to improve job insecurity among temporary employees.

Relationship between long working hours and smoking behaviors: Evidence from population-based cohort studies in Korea.

OBJECTIVES: Long working hours and overwork are growing public health concerns in the Western-Pacific region. We explored the relationship between working hours and smoking behaviors of Korean workers. METHODS: This study included 284 782 observations (50 508 workers) from four nationwide cohort studies in Korea. Using generalized estimating equations, we estimated the associations of working hours with current smoking status, smoking initiation, and smoking cessation within each cohort. Cohort-specific estimates were combined through random-effect meta-analysis. Effect sizes were presented as odds ratios (OR) and 95 confidence intervals (CI). RESULTS: The overall smoking prevalence was 26.8% within the cohorts. The adjusted OR (95% CI) of the association between working hours and current smoking were 1.01 (0.94-1.08) for <35 hours/week, 1.04 (1.01-1.09) for 41-48 hours/week, 1.06 (1.01-1.10) for 49-54 hours/week, and 1.07 (1.04-1.10) for ≥55 hours/week compared with 35-40 hours/week. The adjusted OR (95% CI) of the association between working hours and smoking cessation in the follow-up were 0.93 (0.85-1.02) for <35 hours/week, 0.89 (0.83-0.96) for 41-48 hours/week, 0.87 (0.81-0.95) for 48-54 hours/week, and 0.91 (0.85-0.98) for ≥55 hours/week compared with 35-40 hours/week. No clear associations were observed between working hours and smoking initiation. CONCLUSION: Long working hours are associated with high current smoking risk and reduced likelihood of smoking cessation among Korean workers. Policy interventions are required to promote smoking cessation and reduce excess overwork for individuals experiencing long working hours.

Association between long working hours and engagement in preventive healthcare services in Korean workers: Findings from the Korean National Health and Nutrition Examination Survey.

BACKGROUND: Engagement in preventive healthcare services is crucial for preventing diseases. We explored how working hours are associated with engagement in preventive healthcare services, with a focus on gender differences. METHODS: This cross-sectional study used data from the 2007-2012 Korean National Health and Nutrition Examination Survey. The dependent variable was engagement in each of the five preventive healthcare services (health check-ups, influenza vaccination, and stomach, breast, and cervical cancer screenings). We estimated the prevalence ratios (PRs) and 95% confidence intervals (CIs) using robust Poisson regression. RESULTS: The study analyzed 19,819 workers (9119 women). The adjusted PRs (95% CI) of the association between working ≥55 h per week and engagement in preventive healthcare services among men were 0.95 (0.90-1.00) for health check-ups, 0.86 (0.77-0.96) for influenza vaccination, and 0.95 (0.87-1.03) for stomach cancer screening compared to working 35-40 h per week. Among women, the adjusted PRs (95% CI) of the association between working ≥55 h per week and engagement in preventive healthcare services were 0.84 (0.78-0.91) for health check-ups, 0.82 (0.73-0.92) for influenza vaccination, and 0.88 (0.80-0.97) for stomach, 0.85 (0.78-0.94) for breast, and 0.82 (0.74-0.91) for cervical cancer screenings. CONCLUSION: Long working hours were negatively associated with engagement in preventive healthcare services, and the association was pronounced among female workers. Efforts to promote preventive healthcare participation among individuals with long working hours are necessary, and it is essential to consider the unique vulnerabilities of women when developing such policies.

Association of paternal cadmium and other heavy metal exposure to birth outcomes using propensity score matching.

BACKGROUND: Human exposure to cadmium has various effects on health, especially on male reproductive organs. Although it is widely known that prenatal maternal cadmium exposure can affect birth outcomes, the effect of paternal exposure to cadmium remains unclear. OBJECTIVES: This study aimed to evaluate the effect of paternal cadmium exposure on fetal growth by considering maternal cadmium exposure and exposure to other heavy metals, namely mercury and lead. METHODS: The Mothers and Children's Environmental Health (MOCEH) study is a prospective birth cohort study in Korea. Overall, 1313 families (father-mother-child triple) without child abnormalities and who completed paternal whole blood cadmium assessments were included in this study. Families were divided into two subgroups based on the blood sampling periods, namely early and late pregnancy. Subjects were selected as follows: one family triple with a high level of paternal cadmium and two triples with low levels of paternal cadmium, using the method of propensity score matching. And linear regression analyses were performed. RESULTS: The group with high paternal cadmium exposure (80% or more; 1.93 µg/L) had lower birth weight infants compared to the group with low cadmium concentrations (ß(se) = -0.21(0.10); p-value = 0.0283). After stratification by infant sex, prenatal paternal cadmium exposure significantly reduced the birth weight of females in subgroups of different sampling times, namely early pregnancy (ß(se) = -0.52 (0.22); p-value = 0.0170) and late pregnancy (ß(se) = -0.43 (0.18); p-value = 0.0160). Finally, after performing propensity score matching in the early pregnancy measurement group, it was found that the prenatal exposure of father to cadmium significantly reduced birth weight in females (ß(se) = -0.72(0.25); p-value = 0.0047). CONCLUSION: This study assessed the effect of paternal cadmium exposure on birth outcomes in family units consisting of a father, mother, and child. Prenatal paternal cadmium exposure negatively affected birth weight, especially that of female, considering covariates and other heavy metals exposure, namely mercury and lead.

Health Effects Associated With Humidifier Disinfectant Use: A Systematic Review for Exploration.

BACKGROUND: It has been 10 years since the outbreak of lung disease caused by humidifier disinfectants in Korea, but the health effects have not yet been summarized. Therefore, this study aims to systematically examine the health effects of humidifier disinfectants that have been discovered so far. METHODS: All literature with humidifier disinfectants and their representative components as the main words were collected based on the web, including PubMed, Research Information Sharing Service, and government publication reports. A total of 902 studies were searched, of which 196 were selected. They were divided into four groups: published human studies (group 1), published animal and cytotoxicology studies (group 2), technical reports (group 3), and gray literature (group 4). RESULTS: Out of the 196 studies, 97 (49.5%) were published in peer-reviewed journals as original research. Group 1 consisted of 49 articles (50.5%), while group 2 consisted of 48 articles (49.5%). Overall, respiratory diseases such as humidifier disinfectant associated lung injury, interstitial lung disease, and asthma have a clear correlation, but other effects such as liver, heart, thymus, thyroid, fetal growth, metabolic abnormalities, and eyes are observed in toxicological experimental studies, but have not yet been identified in epidemiologic studies. CONCLUSION: The current level of evidence does not completely rule out the effects of humidifier disinfectants on extrapulmonary disease. Based on the toxicological evidence so far, it is required to monitor the population of humidifier disinfectant exposure continuously to see if similar damage occurs.

The combined effect of long working hours and individual risk factors on cardiovascular disease: An interaction analysis.

OBJECTIVES: We examined whether the effect of long working hours on the risk of developing cardiovascular disease (CVD) differs depending on individual risk factors. METHODS: Seven-year follow-up data were extracted from the 2009 to 2016 waves of the Korea Health Panel Survey. Physician's diagnosis or medication for hypertension, diabetes, dyslipidemia, and obesity were included as chronic disease status. Smoking, drinking alcohol, and exercise levels were considered as lifestyle behavior. Hazard ratios were calculated using the Cox regression models to evaluate the risk of CVD related to chronic diseases and unhealthy behavior, based on working hour groups, after adjusting for other covariates. The interactive effects of long working hours with or without chronic diseases and unhealthy behavior on CVD were assessed using the relative excess risk due to interaction and attributable proportion measures. RESULTS: There was a statistically significant interaction between long working hours and chronic diseases within the population, especially among male participants (P-value for interaction <.01 and .03, respectively). There were no significant interactions between unhealthy behavior and long working hours. CONCLUSIONS: Long working hours and chronic disease have a synergistic negative effect on the risk of CVD.

Occupational physical activity, not leisure-time physical activity, is associated with increased high-sensitivity C reactive protein levels.

OBJECTIVE: This study aims to explore the association between physical activity and high-sensitivity C reactive protein, based on different types of physical activity-occupational and leisure time. METHODS: Using cross-sectional data from the Korea National Health and Nutrition Examination Survey 2015-2018, we explored the association between different types of self-reported physical activity and high levels of high-sensitivity C reactive protein (>3 mg/L). We estimated the ORs for high-level high-sensitivity C reactive protein using multiple logistic regression models after adjusting for covariates from 12 970 eligible subjects (mean age 44.8). RESULTS: Compared with subjects who did not engage in moderate-to-vigorous level of occupational physical activity (OPA), the group that engaged in moderate-to-vigorous level of OPA showed a significantly high OR (1.32, 95% CI (1.03 to 1.69)), whereas the group that engaged in moderate-to-vigorous level of leisure-time physical activity (LPA) yielded a low OR (0.84, 95% CI (0.69 to 1.01)). The group that engaged in moderate-to-vigorous level of OPA but not LPA showed a significantly high OR (1.76, 95% CI (1.27 to 2.45)) compared with subjects who engaged in moderate-to-vigorous level of LPA but not in OPA. CONCLUSIONS: OPA is directly associated with high C reactive protein levels, suggesting that it increases the risk of inflammation.

Inhaled corticosteroids in COPD and the risk for coronary heart disease: a nationwide cohort study.

Inhaled corticosteroids (ICS) might lower the risk of coronary heart disease (CHD) in patients with chronic obstructive pulmonary disease (COPD). This study aimed to assess the association of ICS with the development of CHD in COPD patients by using data from the Korean Nationwide study. Patients who were newly diagnosed with COPD between 2004 and 2013 and who were not diagnosed with coronary heart disease before their diagnosis of COPD were included. Exposure of ICS was incorporated into multivariable Cox regression models using time-dependent methods. To accurately estimate ICS-exposure accumulation, a washout period of 2 years from 2002 to 2003 was applied. Among a total of 4,400 newly diagnosed COPD patients, 771 patients were diagnosed as CHD incident cases during a median follow-up of one year (interquartile range 0.1-2.9). The cumulative dose of ICS was associated with a reduced risk of CHD (adjusted hazard ratio [aHR], 0.68; 95% confidence interval [CI], 0.52-0.89). When the cumulative exposure dose of ICS was divided into quartiles, the aHR for CHD incidence was 0.70 (95% CI, 0.55-0.88) in the highest quartile ICS dose use. The effect of ICS on reducing CHD incidence was pronounced in adults over 55 years, men under 55 years, and former smokers. Our findings demonstrate the role of ICS for the prevention of CHD in COPD patients without a history of CHD. Further research is needed to determine whether a certain amount of ICS exposure in COPD patients is protective against CHD.

Effects of PM10 on mortality in pure COPD and asthma-COPD overlap: difference in exposure duration, gender, and smoking status.

We investigated the effects of particulate matter (PM) on mortality in patients diagnosed with asthma-COPD overlap (ACO) or 'pure COPD'. Subjects from the National Health Insurance Service-National Sample Cohort of Korea, who were aged 40 years or above and had newly diagnosed COPD since 2009 were selected. Finally, 6,313 patients were enrolled and divided into 'pure COPD' and ACO groups. Average PM10 exposure data were obtained using Kriging interpolation from 2001 to 2013. Hazard ratios(HR) were estimated using a time-varying Cox regression model. Exposure to PM10 for 1, 3, and 6 months was associated with an increase in non-accidental mortality in the entire COPD group, especially the ACO group. When a stratified analysis of 3-month exposure was performed by sex, the highest HR was found in women with ACO (HR = 1.153; 95% confidence intervals [CI]: 1.121, 1.185). A stratified analysis according to smoking status showed that ACO patients had the highest HR among never smokers (HR = 1.151; 95% CI; 1.124, 1.178). Average exposure to PM10 was associated with non-accidental mortality in patients with COPD, especially those diagnosed with ACO. In addition, the adverse effects of PM10 exposure are more severe in women and never-smokers.

Association between cadmium and anti-Mullerian hormone in premenopausal women at particular ages.

BACKGROUND: Anti-Mullerian hormone (AMH) in women is secreted by granulosa cells of antral follicles. AMH appears to be a very stable marker for ovarian function. It may be used to diagnosis cases of premature ovarian failure, polycystic ovary syndrome (PCOS), and ovarian tumors. It has been suggested that cadmium exposure can reduce female fecundity. The purpose of this study was to investigate whether environmental exposure to cadmium was associated with alterations in AMH with regards to age. METHODS: In a cross-sectional study, the data of premenopausal women living in Seoul, ranging from 30 to 45 of age was collected. The study included a total of 283 women who completed serum AMH and whole blood cadmium assessments. Linear regression analyses were used in order to examine the association between cadmium and AMH. Given that age was the strongest confounder in both cadmium and AMH concentrations, we stratified subjects by 5 years old and analyzed their data. RESULTS: Geometric mean concentrations of blood cadmium and AMH were 0.97 µg/L and 3.02 ng/ml, respectively. Total association between cadmium and AMH was statistically significant (adjusted coefficient = - 0.34 (0.15), p = 0.02). After stratification, the only age group with a negative association between cadmium and AMH were the women raging between 30 and 35 years (adjusted coefficient = - 0.43 (0.18), p = 0.01). CONCLUSIONS: The results of this study suggest that environmental exposure to cadmium may alter the AMH level of premenopausal women, depending on their age group.

Inhaled corticosteroids in COPD and the risk of lung cancer.

Inhaled corticosteroids (ICS) might reduce the risk of lung cancer by controlling airway inflammation in patients with chronic obstructive pulmonary disease (COPD) because both are associated with chronic inflammation. The objective was to assess the impact of ICS on lung cancer risk reduction in COPD patients. We performed a nested case-control study based on the database of the National Health Insurance Service-National Sample Cohort, a nationally representative cohort of 1,125,691 participants in Korea followed over 11 years. The eligible population was patients aged 30-89 years who were newly diagnosed with COPD and initiated inhaled medications after diagnosis. Cases were defined as individuals diagnosed with lung cancer after the initiation of inhaled medications and were matched with controls by propensity score at a 1:4 ratio. We identified 265 individuals with lung cancer, matched with 1,060 controls. Use of ICS was associated with reduced risk of lung cancer (adjusted hazard ratio [aHR] 0.74, 95% CI 0.57-0.96). The high cumulative ICS dose group, defined as those above the third quartile of ICS dose distribution, had a lower risk of lung cancer than the low cumulative dose group (aHR 0.51, 95% CI 0.34-0.75). The effect of ICS on lung cancer risk reduction was more remarkable in former smokers than current smokers. Additionally, the result was consistent in men regardless of the classification according to ICS use, while it was not significant in women. ICS, particularly at high cumulative dose, might be associated with decreased risk of lung cancer in patients with COPD. Severe COPD frequently warrants treatment with inhaled corticosteroids, which exert immunomodulatory and antiproliferative effects. Despite an association between COPD and increased lung cancer risk, patients on ICS appear to have a reduced likelihood of developing lung cancer. Here, analyzing data from the National Health Insurance Service-National Sample Cohort in Korea, the authors show that ICS use is associated with decreased lung cancer risk in COPD patients. An inverse dose-response relationship was detected, whereby increasing cumulative ICS dose was associated with decreasing lung cancer risk. The effect was most pronounced in men and former smokers.