The impact of long working hours on daily sodium intake.

Background: Long working hours are associated with an increased risk of cardiovascular disease, yet the underlying mechanism(s) remain unclear. The study examines how occupational factors like working hours, shift work, and employment status correlate with dietary choices and sodium intake, impacting hypertension risk. Methods: This study used data from the Korea National Health and Nutrition Examination Survey conducted between 2013 and 2020. The dataset included 8,471 respondents, all of whom were wage workers aged 20 or older and reported working at least 36 hours per week. Individuals who have been previously diagnosed with or are currently diagnosed with hypertension, diabetes, or dyslipidemia were excluded. The average daily sodium intake was assessed via a 24-hour dietary recall method. Average weekly working hours were categorized into 3 groups: 36-40 hours, 41-52 hours, and over 52 hours. Multiple logistic regression models were used. Results: Study findings revealed that 83.7% of participants exceeded the recommended daily sodium intake of 2 g set by the World Health Organization. After adjusting for confounding factors, a positive correlation was observed between average working hours and daily sodium intake. Among males, statistical significance was found in the group with average weekly working hours of 41-52 hours (prevalence ratio [PR]: 1.17; 95% confidence interval [CI]: 1.05-1.30) and the group exceeding 52 hours (PR: 1.22; 95% CI: 1.09-1.38) when comparing the fourth quartile of daily sodium intake to the combined quartiles of Q1, Q2, and Q3. Among females, no significance was noted. Conclusions: Long working hours were associated with increased sodium intake, primarily among male workers. This connection is likely attributed to having less time for home-cooked meals, resulting in higher fast food consumption and dining out. A workplace intervention promoting healthy eating and reducing stress is essential to lower sodium consumption and mitigate hypertension risk.

Differences of nutritional intake habits and Dietary Inflammatory Index score between occupational classifications in the Korean working population.

Background: Human nutrient intake is closely related to the conditions of their workplace. Methods: This study used data from the Korean National Health and Nutritional Examination Survey (KNHANES) conducted between 2016 and 2020. The study population comprised individuals aged 19 to 65 years who were engaged in paid work, excluding soldiers (total = 12,201, male = 5,872, female = 6,329). The primary outcome of interest was the Dietary Inflammatory Index (DII) score, which was calculated using dietary intake data. Generalized linear models were used for statistical analyses. Results: Pink-collar workers had higher DII scores, indicating a potentially higher inflammatory diet than white-collar workers (mean: 2.18 vs. 1.89, p < 0.001). Green and blue-collar workers displayed lower levels of dietary inflammation (green: 1.64 vs. 1.89, p = 0.019, blue: 1.79 vs. 1.89, p = 0.022). After adjusting for sex, age, income, education, and energy intake, the sole trend that persisted was the comparison between white-collar and pink-collar workers. Conclusions: DII scores and dietary patterns differed among occupational groups and genders.

Association between long working hours and unmet dental needs in wage workers.

BACKGROUND: Many previous studies on the reasons behind unmet dental needs focus on economic issues. However, in this research, we aimed to investigate the relationship between long working hours and unmet dental needs while considering the influence of occupational factors in wage workers. METHODS: This study used data from the Korea National Health and Nutrition Examination Survey (2012-2018) and analyzed a sample of 12,104 wage workers. Unmet dental needs were defined as cases in which individuals did not receive dental care, despite their need for examination or treatment, within the last year. Long working hours were defined as exceeding 52 h per week, based on the standard working hours stipulated by the Labor Standards Act. A binomial model was applied to calculate the prevalence ratio through multivariate logistic regression analysis. RESULTS: The prevalence of unmet dental needs was observed in 3,948 cases (32.5%), among which 1,478 attributed their presence to lack of time. The prevalence of unmet dental needs showed an inverse relationship with the education level and household income. The wage workers who worked long hours had the highest prevalence of unmet dental needs. Long working hours were found to be 1.18 times (95% CI 1.07-1.29) more likely to result in unmet dental care compared to working less than 40 h. The relationship between long working hours and unmet dental needs were statistically significant only in men (PR 1.24, 95% CI 1.07-1.43). However, the relationship between long working hours and unmet dental needs owing to time were in both men and women (men: PR 1.59, 95% CI 1.20-2.11, women: PR 1.90, 95% CI 1.48-2.43). CONCLUSIONS: This study confirmed that long working hours and unmet dental needs are related when occupational factors are taken into consideration, despite the absence of oral health indicators. Using this study as a reference, further research is necessary to identify the underlying causes of unmet dental care and to improve access to dental services in the future.

Long working hours and increased risks of lean non-alcoholic fatty liver disease among Korean men and women.

Despite the increasing prevalence of lean nonalcoholic fatty liver disease (NAFLD), its risk factors are not well established. We examined the association between long working hours and incident NAFLD in lean Korean workers with emphasis on sex-based effect modification. This cohort study involved 46,113 non-overweight (BMI < 23 kg/m2) and NAFLD-free Korean workers (mean age, 35.5 years). Working hours were categorized into 35-40 (reference), 41-52, and ≥ 53 h. The presence of fatty liver and its severity were determined using ultrasonography and NAFLD fibrosis score (NFS), respectively. Hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated using parametric proportional hazards models. Incident cases of 5901 lean NAFLD developed over a median follow-up of 3.8 years. The incidence of lean NAFLD increased with increasing working hours with a stronger association in men than in women (P for interaction < 0.001). For men, multivariable-adjusted HRs (95% CIs) for lean NAFLD in time-dependent models comparing working hours of 41-52 and ≥ 53 h compared to the reference category were 1.17 (1.07-1.28) and 1.25 (1.12-1.39), respectively. The excess relative risk of developing lean NAFLD with intermediate/high NFS was observed in working hours of 41-52 and ≥ 53 h with a corresponding HR of 1.66 (1.13-2.43) and 1.54 (0.94-2.51), respectively. Conversely, no significant associations were found between working hours and incidence of lean NAFLD in women. In conclusion, long working hours were significantly associated with an increased incidence of lean NAFLD and its severe form in men but not in women.

Comparison of Work-Related Stress in Cluster of Workers' Suicides in Korea: Analysis of Industrial Accident Compensation Insurance, 2010-2017.

BACKGROUND: There is limited research on the heterogeneity of worker suicides. We compared differences in workers' suicides by clustering suicide deaths. METHODS: From 2010 to 2017, 353 suicide deaths were claimed in the Industrial Accident Compensation Insurance; variables were coded using a standardized methodology. A two-step cluster analysis classified the clusters based on demographic and employment conditions. Details of the suicide, clinical variables, personal stresses, and work-related stresses were compared using the chi-square test and one-way analysis of variance. RESULTS: We identified five clusters and they differed particularly in work-related stress. "Responsibility-burdened type" experienced excessive responsibility as managers; "role-changed type" experienced a sudden and unpredictable role change as clerks or sales workers; "risk-exposed type" experienced physical risk factors at work (working alone, outdoors, and in shifts) as machine operating and assembling workers, or craft and related trades workers; "job-insecurity type" experienced unstable employment (irregular, nonpermanent) as elementary or service workers; "workplace-violence type" was mainly unmarried women who lived alone, and experienced interpersonal conflict and violence as professionals and related workers. There were no differences between clusters in clinical variables (except problem drinking) and personal stresses. CONCLUSION: Interventions to alleviate work-related stress in worker clusters are needed to prevent suicide in workers.

The effect of first- and third-generation prophylactic antibiotics on hospitalization and medical expenditures for cardiac surgery.

BACKGROUND: This study investigated the efficacy of first-generation (cefazolin) and third-generation (ceftizoxime) prophylactic antibiotics in patients undergoing cardiac surgery and the incidence of surgical site infections, hospitalizations, and medical costs. METHODS: All adult patients (≥ 20 years) undergoing cardiac surgery at one hospital from January 01, 2009, to December 31, 2016, were included in this study. A single prophylactic antibiotic was administered at a dose of 1 g within one hour of the surgical incision and for three days after surgery at eight-hour intervals. After propensity score matching, 194 patients in each antibiotic prophylaxis group (first-generation vs third-generation) were analyzed. Among the 388 patients, the incidence of surgical site infections was compared according to the type of prophylactic antibiotic, and risk factors were evaluated by chi-squared tests followed by multivariate logistic regression analysis. RESULTS: The incidence of deep surgical site infections was significantly lower in the first-generation group (5.7%) than in the third-generation group (16.5%). The pathogens isolated from the surgical infection sites were similarly distributed in both groups. However, the prevalence of highly infectious gram-positive bacteria was more than that of gram-negative bacteria (67% vs 23%). The preoperative hospitalization duration, mean operation time, and ventilator use time were similar in both groups, but the postoperative hospitalization duration was significantly shorter in the first-generation group (25.5 days) than in the third-generation group (29.8 days). In addition, the medical costs were lower in the first-generation group (20,594 USD) than in the third-generation group (26,488 USD). CONCLUSION: In conclusion, the first-generation prophylactic antibiotic was better than the third-generation in reducing surgical site infection rates, hospitalization length, and medical expenditures.

Pregnancy loss and Income in the Republic of Korea using National Health Insurance Service Data, 2008-2014.

BACKGROUND: Although unintentional pregnancy loss is common, national representative statistics are lacking in high-income East Asian countries undergoing rapid demographic changes. It is necessary to confirm the income inequality of pregnancy loss even in universal national health insurance. METHOD: Using National Health Insurance Service data between 2008 and 2014, the annual prevalence of pregnancy loss was enumerated, and differences in pregnancy loss according to age and income levels were assessed by multivariable Poisson regression. Joint-point regression was used to examine the trend of pregnancy loss. RESULT: On average, there was a 15.0% annual pregnancy loss among 3,941,020 pregnancy cases from 2008 to 2014. Pregnancy loss inequality increased stepwise with income levels except for the highest income group. After adjusting for income levels, the annual percent change of age-standardized prevalence significantly increased by 2.6% every year since 2011. CONCLUSION: Even in high-income countries with universal national health insurance, income inequality in pregnancy loss is observed. Further appraisal is needed to explain the increasing trend of pregnancy loss between 2011 and 2014 even after adjusting income.

Socio-demographic factors and lifestyle associated with symptomatic hemorrhoids: Big data analysis using the National Health insurance Service-National Health screening cohort (NHIS-HEALS) database in Korea.

OBJECTIVE: The prevalence of hemorrhoids has been reported to be 7-14%. However, there have been no large-scale studies. This study aims to investigate the incidence of hemorrhoids in Korea by analyzing big data and to find the associated risk factors. METHODS: This was a retrospective analysis using the Health Insurance Cohort database of the National Health Insurance Corporation of Korea in 2002-2015. The study was divided into two models: the diagnostic (DM) and surgical model (SM). Socio-demographic and lifestyle behavioral characteristics were analyzed as risk factors. RESULTS: Overall, 467,567 participants were included. The incidence density of hemorrhoids was 13.9 and 5.7 per 1000 person-years in the DM and SM, respectively. Hemorrhoids occurred more frequently in men and metropolitan areas in both models. The incidence was highest in the 40s. The incidence rates were highest in the high income, smoking, alcohol and the exercise group of 1-4 times a week in both models. The adjusted hazard ratio (HR) was higher in men and decreased with increasing age. It was higher in the metropolitan area. The high-income level and alcohol consumption were risk factors in the DM and SM, respectively. The HR of the exercise group was higher than that of the non-exercise group in both models. CONCLUSIONS: The diagnostic and surgical incidence density was 13.9 and 5.7 per 1000 person-years, respectively. Hemorrhoids occurred most frequently in men in their 40s. The metropolitan area, high income level and alcohol consumption were associated with an increased frequency of hemorrhoids.

Parkinson's disease in a worker exposed to insecticides at a greenhouse.

BACKGROUND: Parkinson's disease (PD) is a rare, neurodegenerative disease with various occupational and environmental risk factors. Exposure to specific pesticides contributes significantly to the incidence of PD. However, it is difficult to measure the level of pesticide exposure in workers. This study presents the first case recognized the work-relatedness between PD and pesticide exposure. CASE PRESENTATION: A 68-year-old male was diagnosed with PD after working with pesticides at a tomato greenhouse for 12 years and 5 months. From the results of a field study, it was reasonable to assume that the patient had been exposed to a significant level of various insecticides. In the present report, we described the first accepted case of work-relatedness between PD and exposure to pesticides. The evaluation was conducted using the following steps: we ruled out other possible risk factors including additional occupational history and personal risk factors, we assessed the work environment, surveyed possible exposures, found proper epidemiological evidence, and calculated the probability of causation. The work-relatedness was determined through the review of epidemiological evidence and estimation of exposure situation and level, and biological plausibility. We also decided work-relatedness based on the exposure of PD related pesticides with identified biologically plausible and the presumption that the exposure level would be high due to the working process. CONCLUSIONS: In this case, the field study and epidemiological results supported the work-relatedness of PD and exposure to pesticides. Moreover, the results of previous studies have confirmed a causal relationship between exposure to pesticides and PD.

Occupation, work-related stress, and personal characteristics among suicide deaths with occupation-related compensation claims in Korea.

OBJECTIVES: This study compared differences in age-standardized suicide mortality rates, personal characteristics (demographics, employment conditions, and details of suicide), and work-related stress by gender and occupation among workers who had committed suicide in Korea. METHODS: Data comprised 413 suicide death claims lodged with the Industrial Accident Compensation Insurance (IACI) from 2010 to 2018, which were coded. We calculated age-standardized suicide mortality rates by gender and occupation. The chi-square test, Fisher's exact test, and t-test were conducted to examine gender differences. Frequency and percentage distribution by gender and occupation were calculated using descriptive statistics. RESULTS: Regardless of gender, age-standardized suicide mortality rate was highest among "Managers." Women who died by suicide were significantly younger and more likely to be unmarried, live alone, and have fewer years of continuous employment than men. "Managers," "Professionals and Related Workers," and "Clerks" experienced similar work-related stresses, including "Difficult work to achieve," "Fail to achieve allocation workload," and "Change of job contents or workload." "Skilled Agricultural, Forestry and Fishery Workers," "Craft and Related Trades Workers," and "Equipment, Machine Operating and Assembling Workers" had higher work-related stress related to "Severe disease/injury" or "Causing a serious accident" compared with other workers. CONCLUSIONS: Work-related stress related to suicide deaths differed by gender and occupation. The gender gap of labor market participation in Korea may affect gender differences in terms of demographics and employment conditions among workers who died by suicide. Our study suggests that gender- and occupation-specific strategies and policies to reduce work-related stress can prevent suicide among workers.

Clinical effects of slim-diet, with lifestyle modification for childhood obesity in community-based healthcare program: A case series.

RATIONALE: Although there are several reports on the effect of herbal medicine on weight loss in adults, evidence supporting its efficacy and safety in obese pediatrics is insufficient. Herein, we clinically investigated the preliminary experience of community-based healthcare program in cases of childhood obesity treated with an herbal complex, Slim-diet (SD), along with lifestyle modification. PATIENT CONCERNS: Seventeen subjects with childhood obesity participated in a community-based healthcare program, which consisted of twice-a-week play type physical activity and dietary counseling program with simultaneous twice-a-day administration of SD for 4 weeks. DIAGNOSES: The data of 13 obese pediatrics (body mass index [BMI] ≥ the 95th percentile for children of the same age and sex) in their 3rd to 6th grade who finally completed at least 6 visits out of a total of 8 visits of the program including baseline and endpoint assessments were analyzed. INTERVENTIONS: Participants received 20 g of SD daily. Simultaneously, play-type physical activity program with an exercise therapist and dietary counseling with a dietitian for lifestyle modification were conducted at every visit. Body composition, blood chemistry, the Korean Youth Physical Activity Questionnaire (KYPAQ) score, and the preference for salt density and sugar content were assessed at baseline and endpoint. OUTCOMES: After SD administration, body mass index decreased from 26.74 ±â€Š2.11 kg/m to 26.50 ±â€Š2.20 kg/m (P < .05) with statistically significant increases in height, weight, and skeletal muscle mass. The results of blood chemistry and the KYPAQ score showed no significant change. The preferences for salt density were improved in 8, maintained in 2, and worsened in 3 participants and those for sugar content were improved in 6 and maintained in 7 participants with no worsening. LESSONS: In the present study, we showed the clinical effects of SD with lifestyle modification in patients with childhood obesity who participated in community-based healthcare program. Further clinical studies investigating the effects of SD are required.

Descriptive analysis of prevalence and medical expenses of cancer, cardio-cerebrovascular disease, psychiatric disease, and musculoskeletal disease in Korean firefighters.

BACKGROUND: Firefighters are exposed to many dangerous working conditions. Many studies have identified the risk of disease for firefighters, but only a few studies have addressed the medical expenses of firefighters, which represents a concrete scale of disease. Our purpose in this study was to determine the medical expenditures of firefighters to assess the overall scale of disease in Korea. We focused on cancer, mental disorders, cardio-cerebrovascular disease, and musculoskeletal disease, the prevalence of which was expected to be high in firefighters. METHODS: This study utilized National Health Insurance Service data. We targeted firefighters, police officers, and government officials. We classified disease based on the 10th revision of the International Statistical Classification of Diseases and Related Health Problems codes. We compared prevalence by the age-standardized prevalence rate, considering standard distribution of the population. Medical expenditure of disease was defined as outpatient fees, hospitalization fees, and drug costs. Total medical expenditures were calculated by the sum of those 3 categories. RESULTS: The age-standardized prevalence of cancer, mental disorders, and cardiovascular disease in firefighters was slightly higher than or similar to that of government officials and police officers (no significant difference). However, medical expenditures for stomach cancer, mental disorders, and most cardio-cerebrovascular diseases were higher in firefighters than in others. In particular, firefighters spent 12 times more money for ischemic heart disease than did government officials. Of musculoskeletal diseases, lumbar disc disorder had the highest expenditures among firefighters. CONCLUSIONS: The age-standardized prevalence of most of diseases of firefighters was not as high as in the other groups, but the medical expenses of firefighters were much higher than those of government officials and police officers.

A case of acute organic solvent poisoning during epoxy coating.

BACKGROUND: In the construction industry, maintaining health and safety of workers often challenging. Among the workers at construction sites, painters are at particular risk of respiratory diseases and neurotoxicity. However, in Korea there is weak enforcement of workers' health and safety practices in the construction industry in Korea. Poisonings frequently occur at (semi)closed construction sites. In this study, we report a case of acute organic solvent poisoning during construction site painting. CASE PRESENTATION: A 71-year-old man was found unconscious at a construction site and immediately transferred to the emergency room. The consciousness level was 'stupor state' and the body temperature was hypothermic, at 32 degrees (Celsius). There were no acute brain or cardiac lesions that would have accounted for the faintness. In addition, blood and urine tests did not indicate a cause of loss of consciousness. He had been painting epoxy to waterproof the basement floor before fainting. According to exposure simulation, the patient was overexposed to various organic solvents, such as approximately 316-624 ppm toluene during the work before fainting. Considering the ventilation status of the workplace and the status of no protection, it is considered that exposure through the respiratory tract was considerable. CONCLUSIONS: The patient in this case lost consciousness during the epoxy coating in a semi-enclosed space. It can be judged as a result of acute poisoning caused by organic solvent exposure and considered to be highly related to work environment.

The relationship between hormone replacement therapy and periodontal disease in postmenopausal women: a cross-sectional study the Korea National Health and Nutrition Examination Survey from 2007 to 2012.

BACKGROUND: The purpose of this study was to investigate the relationship between hormone replacement therapy (HRT) and periodontal disease in postmenopausal women using data from the 4th and 5th Korea National Health and Nutrition Examination Survey (KNHANES). METHODS: The study included data from 5,482 postmenopausal women aged 45-74 years in the 2007-2012 KNHANES. The use of female HRT for at least one month was reclassified as HRT+/HRT-. The Community Periodontal Index of Treatment Needs (CPITN) was used to assess periodontal status. Propensity score matching (PSM) was used to control selection bias, and factors affecting education, family income, and age of menopause were used as covariates in PSM. A chi-square test was used to confirm the bivariate relationship between the variables. Binary logistic regression analysis was used to adjust for confounders (age, education, family income, body mass index, age of menopause, alcohol, smoking, dental clinic visits in the past one year, use of oral care products and frequency of tooth brushing per day). RESULTS: After adjusting for all covariates, HRT was associated with periodontal disease (OR: 0.79; 95% CI: 0.66-0.94). In particular, the relationship between HRT and periodontal disease was more evident in those with menopause under 45 years of age disease (OR: 0.55; 95% CI: 0.35-0.87). CONCLUSIONS: The results of this study supported that it is important that hormone therapy be actively considered in the policy towards postmenopausal women. Especially, health programs such as hormone replacement therapy, non-smoking, and use of oral care products are needed for women who undergo premature menopause.

Overwork-related disorders and recent improvement of national policy in South Korea.

OBJECTIVES: Recently, overwork-related disorders have become a major public health concern in Korea. This study investigated the current trends of working hours, causes of death in the working population, and compensation rates. METHODS: We reviewed the current trends of working hours, cause of death statistics in the working population, industrial accident compensation insurance (IACI) statistics, issues of compensation and prevention of work-related cerebro-cardio vascular diseases (CCVDs), mental disorders, and suicide. RESULTS: Although weekly working hours and the proportion of long working days have decreased, workers in small companies with fewer than five employees and those in the service sector continue to work long hours. The age standardized mortality due to CCVD and suicide was highest among those with managerial roles. In total, 589 CCVD cases and 104 mental disorder or suicide cases were compensated as occupational diseases in 2017. Between 2016 and 2017, 61% of 59 compensated suicides were related to overwork, specifically: long working hours, increased responsibility, or increased workload. The Korean government has introduced various policies to reduce working hours and to increase compensation approval rate for overwork-related CCVDs. Stakeholders have called for the introduction of independent laws to prevent overwork-related disorders, change organizational culture, and address the blind spots of the IACI Act and Labor Standard Act. CONCLUSIONS: Prevention and compensation policies have improved working conditions in Korea, but there remains much to be done. This review significantly contributes to the understanding of the overall policies and research to prevent overwork-related disorders in Korea.

The Fourth Industrial Revolution and Its Impact on Occupational Health and Safety, Worker's Compensation and Labor Conditions.

The "fourth industrial revolution" (FIR) is an age of advanced technology based on information and communication. FIR has a more powerful impact on the economy than in the past. However, the prospects for the labor environment are uncertain. The purpose of this study is to anticipate and prepare for occupational health and safety (OHS) issues. In FIR, nonstandard employment will be common. As a result, it is difficult to receive OHS services and compensation. Excessive trust in new technologies can lead to large-scale or new forms of accidents. Global business networks will cause destruction of workers' biorhythms, some cancers, overwork, and task complexity. The social disconnection because of an independent work will be a risk for worker's mental health. The union bonds will weaken, and it will be difficult to apply standardized OHS regulations to multinational enterprises. To cope with the new OHS issues, we need to establish new concepts of "decent work" and standardize regulations, which apply to enterprises in each country, develop public health as an OHS service, monitor emerging OHS events and networks among independent workers, and nurture experts who are responsible for new OHS issues.

Risk of olfactory dysfunction of the workers in the automobile repair, printing, shoemaking and plating industries in Korea: a cross-sectional study.

OBJECTIVES: The present study was performed to investigate the prevalence of olfactory dysfunction in workers exposed to hazardous substances in a variety of occupations in Korea. METHODS: We designed a cross-sectional study. The exposed group (n=296) consisted of Korean workers in the automobile repair, printing, shoemaking and plating industries and was compared with office workers (non-exposed group, n=99). A self-report questionnaire was administered to the subjects for demographic characteristics. In addition, olfactory function was evaluated using the Korean version of Sniffin's Stick (KVSS) I and II test, which has been reported to be valid and reliable in Korean subjects. KVSS I score ≥7 or KVSS II score ≥30 was classified as normal, KVSS I score <7 or KVSS II score <30 was classified as oflactory dysfunction. The statistical analyses were performed with olfactory dysfunction as a dependent variable to calculate prevalence ratio (PR) of the exposed group. RESULTS: The prevalence of olfactory dysfunction was 21.2% in office, 45.1% in automobile repair, 69.7% in printing and 88.9% in shoemaking and plating workers. The adjusted PR was highest in plating (3.589, 95% CI 1.957 to 6.583), followed by shoemaking (3.136, 95% CI 1.763 to 5.579), printing (2.669, 95% CI 1.610 to 4.424) and automobile repair (1.914, 95% CI 1.105 to 3.317) workers. CONCLUSIONS: In comparison with office workers, the prevalence of olfactory dysfunction and the PR of olfactory dysfunction were very high in the four occupational groups. This finding could be an important basis for establishing the olfactory dysfunction prevention policy for workers who are exposed to hazardous substances or work in high-risk occupations.

Correction to: Guidelines for recognition of occupational cancers in Korea: the results of scientific review by Korean Society of Occupational and Environmental Medicine (2013-2016).

[This corrects the article DOI: 10.1186/s40557-018-0223-2.].

Does formaldehyde have a causal association with nasopharyngeal cancer and leukaemia?

BACKGROUND: The South Korean criteria for occupational diseases were amended in July 2013. These criteria included formaldehyde as a newly defined occupational carcinogen, based on cases of "leukemia or nasopharyngeal cancer caused by formaldehyde exposure". This inclusion was based on the Internal Agency for Research on Cancer classification, which classified formaldehyde as definite human carcinogen for nasopharyngeal cancer in 2004 and leukemia in 2012. METHODS: We reviewed reports regarding the causal relationship between occupational exposure to formaldehyde in Korea and the development of these cancers, in order to determine whether these cases were work-related. RESULTS: Previous reports regarding excess mortality from nasopharyngeal cancer caused by formaldehyde exposure seemed to be influenced by excess mortality from a single plant. The recent meta-risk for nasopharyngeal cancer was significantly increased in case-control studies, but was null for cohort studies (excluding unexplained clusters of nasopharyngeal cancers). A recent analysis of the largest industrial cohort revealed elevated risks of both leukemia and Hodgkin lymphoma at the peak formaldehyde exposure, and both cancers exhibited significant dose-response relationships. A nested case-control study of embalmers revealed that mortality from myeloid leukemia increased significantly with increasing numbers of embalms and with increasing formaldehyde exposure. The recent meta-risks for all leukemia and myeloid leukemia increased significantly. In South Korea, a few cases were considered occupational cancers as a result of mixed exposures to various chemicals (e.g., benzene), although no cases were compensated for formaldehyde exposure. The peak formaldehyde exposure levels in Korea were 2.70-14.8 ppm in a small number of specialized studies, which considered anatomy students, endoscopy employees who handled biopsy specimens, and manufacturing workers who were exposed to high temperatures. CONCLUSION: Additional evidence is needed to confirm the relationship between formaldehyde exposure and nasopharyngeal cancer. All lymphohematopoietic malignancies, including leukemia, should be considered in cases with occupational formaldehyde exposure.

The relationship between night work and breast cancer.

BACKGROUND: Since the International Agency for Research on Cancer classified shift work that involves circadian disruption as "probably carcinogenic to humans," there has been growing concern on the relationship between night work and breast cancer. In Korea, about 10-15% of workers are engaged in night-shift work, and breast cancer is one of the most common cancers in women. The purpose of this study was to review epidemiologic evidence on the relationship between night work and breast cancer. METHODS: We reviewed 21 original articles and 5 meta analyses on relationship between nightwork and breast cancer, and investigated the compensation criteria of Denmark. RESULTS: The association between breast cancer and night work has been reported by numerous epidemiologic studies, including cohort studies, case-control studies, and meta-analysis. However, a dose-response relationship has not clearly emerged among workers exposed to less than 20 years of night work. CONCLUSION: Although there are some limitations to the epidemiological studies so far, further consideration of breast cancer cases in patients with high exposure to night work is needed to assess breast cancer as a work-related disease.