Evaluation of Temporal Trends of Lead Exposure in Korean Workers Using Workplace Monitoring Data

Background@#Lead, which is widely used in various industrial settings, is a major health hazard for manufacturing workers. Therefore, control of lead exposure has been implemented in an effort to prevent lead-related health problems. In this study, our aim was to evaluate temporal trends in occupational lead exposure in Korean lead workers using data from monitoring of workplace exposure. @*Methods@#A nationwide work environment monitoring database, data from a work environment monitoring institution, and data extracted from a review paper were utilized. Different versions of standard industrial classification codes were aligned with the 10th Korean Standard Industrial Classification, which is generally consistent with the 4th revision of the International Standard Industrial Classification. The multiple data sources were combined and temporal trends over the period from 1994–2021 were estimated. In addition, separate estimation of temporal trends in the storage battery manufacturing industry over the period from 1987–2021 was also performed. @*Results@#A total of 444,296 personal airborne lead measurements were used for the estimation process. The temporal trends in occupational exposure to lead declined by −6% annually over the study period. In particular, levels of lead exposure in the storage battery manufacturing industry showed a steeper decline of −12% annually. @*Conclusions@#Findings of our study showed that occupational exposure to lead declined over the period from 1994 to 2021 in Korea. However, adverse effects of exposure to lead on health should be regarded with caution. The results will be useful in conduct of epidemiological studies examining lead-related effects on health.

Cohort Study Protocol: A Cohort of Korean Atomic Bomb Survivors and Their Offspring / 예방의학회지

In 1945, atomic bombs were dropped on Hiroshima and Nagasaki. Approximately 70 000 Koreans are estimated to have been exposed to radiation from atomic bombs at that time. After Korea’s Liberation Day, approximately 23 000 of these people returned to Korea. To investigate the long-term health and hereditary effects of atomic bomb exposure on the offspring, cohort studies have been conducted on atomic bomb survivors in Japan. This study is an ongoing cohort study to determine the health status of Korean atomic bomb survivors and investigate whether any health effects were inherited by their offspring. Atomic bomb survivors are defined by the Special Act On the Support for Korean Atomic Bomb Victims, and their offspring are identified by participating atomic bomb survivors. As of 2024, we plan to recruit 1500 atomic bomb survivors and their offspring, including 200 trios with more than 300 people. Questionnaires regarding socio-demographic factors, health behaviors, past medical history, laboratory tests, and pedigree information comprise the data collected to minimize survival bias. For the 200 trios, whole-genome analysis is planned to identify de novo mutations in atomic bomb survivors and to compare the prevalence of de novo mutations with trios in the general population. Active follow-up based on telephone surveys and passive follow-up with linkage to the Korean Red Cross, National Health Insurance Service, death registry, and Korea Central Cancer Registry data are ongoing. By combining pedigree information with the findings of trio-based whole-genome analysis, the results will elucidate the hereditary health effects of atomic bomb exposure.

Comparison of Proportional Mortality Between Korean Atomic Bomb Survivors and the General Population During 1992–2019

Background@#Atomic bombs dropped on Hiroshima and Nagasaki in Japan in August 1945 were estimated to have killed approximately 70,000 Koreans. In Japan, studies on the health status and mortality of atomic bomb survivors compared with the non-exposed population have been conducted. However, there have been no studies related to the mortality of Korean atomic bomb survivors. Therefore, we aimed to study the cause of death of atomic bomb survivors compared to that of the general population. @*Methods@#Of 2,299 atomic bomb survivors registered with the Korean Red Cross, 2,176 were included in the study. In the general population, the number of deaths by age group was calculated from 1992 to 2019, and 6,377,781 individuals were assessed. Causes of death were categorized according to the Korean Standard Classification of Diseases. To compare the proportional mortality between the two groups, the P value for the ratio test was confirmed, and the Cochran-Armitage trend test and χ 2 test were performed to determine the cause of death according to the distance from the hypocenter. @*Results@#Diseases of the circulatory system were the most common cause of death (25.4%), followed by neoplasms (25.1%) and diseases of the respiratory system (10.6%) in atomic bomb survivors who died between 1992 and 2019. The proportional mortality associated with respiratory diseases, nervous system diseases, and other diseases among atomic bomb survivors was higher than that of the general population. Of the dead people between 1992 and 2019, the age at death of survivors who were exposed at a close distance was younger than those who were exposed at a greater distance. @*Conclusion@#Overall, proportional mortality of respiratory diseases and nervous system diseases was high in atomic bomb survivors, compared with the general population. Further studies on the health status of Korean atomic bomb survivors are needed.

Atypical Dysphagia in an Anti-Hu Positive Non-Small-Cell Lung Cancer Patient / 대한연하장애학회지

Anti-Hu antibodies usually present in small cell lung cancer are associated with encephalomyelitis, encephalitis, cerebellitis, and neuropathies. However, to our knowledge, non-small-cell lung cancer (NSCLC) related anti-Hu syndrome presenting acute exacerbation of dysphagia has not been reported. Herein, we report a rare case of atypical dysphagia in an anti-Hu positive NSCLC patient resulting in a fatal outcome. A 73-year-old Korean male went through surgical interventions for recurrent tongue cancer and NSCLC. After the surgery, he resumed full oral feeding with a regular diet. However, four weeks later, he developed a sudden difficulty in swallowing. Neck computed tomography angiography, brain magnetic resonance imaging, brain positron emission tomography, computed tomography and electromyography all showed nonspecific findings. A paraneoplastic antibody test was positive for anti-Hu antibodies. His dysphagia worsened and eventually, he expired due to malignant pleural effusion. Our case shows that anti-Hu antibodies can be expressed in NSCLC and when associated with dysphagia, the outcome can be fatal.

Unusual Lower Back Pain on the Non-Articulated Side in Patient with Bertolotti’s Syndrome

Bertolotti’s syndrome (BS) refers to chronic low back pain (LBP) associated with lumbosacral transitional vertebrae (LSTV). Many studies suggest that the anomalous articulation alters biomechanics, resulting in discomfort on the ipsilateral side. Herein, we present an unusual case of BS presenting pain on the non-articulated side. A 46-year-old man visited our clinic with history of chronic LBP, refractory to treatment of analgesics, modalities and manual therapies. Electrodiagnostic studies showed no evidence of lumbosacral radiculopathy. Radiographies noted unilateral pseudoarticulation of L5∼S1 vertebrae, on the contralateral side of his pain. The pain improved dramatically after sacroiliac joint block and facet joint block with iliolumbar ligament infiltration on the non-articulated side. Clinicians should be cautious that the unaffected joint in BS may serve an important role in altered lumbopelvic biomechanism, since it might eventually lead to intractable chronic LBP when overlooked.

Association between Relative Preference for Vegetables and Meat and Cancer Incidence in Korean Adults: A Nationwide Population-based Retrospective Cohort Study / 대한지역사회영양학회지

Objectives@#We aimed to examine the association between the relative preference for vegetables and meat and cancer incidence, in a population-based retrospective cohort in Korea. @*Methods@#We included 10,148,131 participants (5,794,124 men; 4,354,007 women) who underwent national health screening between 2004 and 2005 from the National Health Information Database of the National Health Insurance Service (NHIS-NHID). Participants were asked whether they preferred consuming 1) vegetables more often, 2) both vegetables and meat or 3) meat more often. Participants were followed up to Dec. 31, 2017. All cancer and eighteen common cancer cases were identified through the code from the International Classification of Diseases, 10th revision. We estimated sexspecific relative risks and 95% confidence intervals, adjusting for age, body mass index, alcohol consumption, smoking, physical activity, and income level. @*Results@#During an average follow-up of 12.4 years, 714,170 cancer cases were documented. In men, consuming meat more often was associated with lower risk of esophageal, liver, and stomach cancers, but higher risk of lung and kidney cancers. Consuming both vegetables and meat was associated with higher risk of prostate cancer, but with lower risk of esophageal, liver, and stomach cancers in men. In women, consuming meat more often was associated with a higher risk of colorectal cancer and breast, endometrial, and cervical cancers diagnosed before the age of 50. Consuming both vegetables and meat was associated with lower risk of liver cancer in women. @*Conclusions@#Our study suggests a potential link between vegetable and meat intake and cancer incidence in the Korean population. Further investigation on the association between the intake of specific types of vegetables and meat and cancer risk in Korean prospective cohort studies is needed.

Unusual Lower Back Pain on the Non-Articulated Side in Patient with Bertolotti’s Syndrome

Bertolotti’s syndrome (BS) refers to chronic low back pain (LBP) associated with lumbosacral transitional vertebrae (LSTV). Many studies suggest that the anomalous articulation alters biomechanics, resulting in discomfort on the ipsilateral side. Herein, we present an unusual case of BS presenting pain on the non-articulated side. A 46-year-old man visited our clinic with history of chronic LBP, refractory to treatment of analgesics, modalities and manual therapies. Electrodiagnostic studies showed no evidence of lumbosacral radiculopathy. Radiographies noted unilateral pseudoarticulation of L5∼S1 vertebrae, on the contralateral side of his pain. The pain improved dramatically after sacroiliac joint block and facet joint block with iliolumbar ligament infiltration on the non-articulated side. Clinicians should be cautious that the unaffected joint in BS may serve an important role in altered lumbopelvic biomechanism, since it might eventually lead to intractable chronic LBP when overlooked.

Estimation of Lead Exposure Intensity by Industry Using Nationwide Exposure Databases in Korea

Background@#In a previous study, we estimated exposure prevalence and the number of workers exposed to carcinogens by industry in Korea. The present study aimed to evaluate the optimal exposure intensity indicators of airborne lead exposure by comparing to blood lead measurements for the future development of the carcinogen exposure intensity database. @*Methods@#Data concerning airborne lead measurements and blood lead levels were collected from nationwide occupational exposure databases, compiled between 2015 and 2016. Summary statistics, including the arithmetic mean (AM), geometric mean (GM), and 95th percentile level (X95) were calculated by industry both for airborne lead and blood lead measurements. Since many measurements were below the limits of detection (LODs), the simple replacement with half of the LOD and maximum likelihood estimation (MLE) methods were used for statistical analysis. For examining the optimal exposure indicator of airborne lead exposure, blood lead levels were used as reference data for subsequent rank correlation analyses. @*Results@#A total of 19,637 airborne lead measurements and 32,848 blood lead measurements were used. In general, simple replacement showed a higher correlation than MLE. The results showed that AM and X95 using simple replacement could be used as optimal exposure intensity indicators, while X95 showed better correlations than AM in industries with 20 or more measurements. @*Conclusion@#Our results showed that AM or X95 could be potential candidates for exposure intensity indicators in the Korean carcinogen exposure database. Especially, X95 is an optimal indicator where there are enough measurements to compute X95 values.

Increased risk of gastric cancer in workers with occupational dust exposure

Background/Aims@#Workers who are exposed to dust in the workplace tend to show a higher incidence of gastric cancer. Nevertheless, scientific evidence to support an association between dust exposure and the risk of gastric cancer is inadequate. This study aimed to investigate whether or not occupational dust exposure influences the risk of gastric cancer. @*Methods@#We collected the electronic data from the Pneumoconiosis Health Examination (PHE) program, provided by the Ministry of Employment and Labor and the Korea Workers’ Compensation and Welfare Service from 2002 to 2017. The PHE database was linked to the National Health Insurances databases. The age-standardized incidence ratio (SIR) and 95% confidence intervals (CIs) of the risk of gastric cancers were evaluated in workers with occupational dust exposure, and the results were compared to those in the general population. @*Results@#From 2004 to 2015, 1,543 cases of gastric cancer were observed in the male participants, as compared with 1,174 of expected cases, which yielded an SIR of 1.314 (95% CI, 1.249 to 1.380). Under dust exposure, the risk of gastric cancer was increased 23.9% in the male participants (95% CI, 19.9 to 27.5), and the degree of impairment of lung function was inversely related to the risk of gastric cancer. @*Conclusions@#Workers with occupational dust exposure were at higher risk of developing gastric cancer than the general population. Thus, future efforts for the prevention of gastric cancer are necessary for dust exposed workers.

Association between Relative Preference for Vegetables and Meat and Cancer Incidence in Korean Adults: A Nationwide Population-based Retrospective Cohort Study / 대한지역사회영양학회지

Objectives@#We aimed to examine the association between the relative preference for vegetables and meat and cancer incidence, in a population-based retrospective cohort in Korea. @*Methods@#We included 10,148,131 participants (5,794,124 men; 4,354,007 women) who underwent national health screening between 2004 and 2005 from the National Health Information Database of the National Health Insurance Service (NHIS-NHID). Participants were asked whether they preferred consuming 1) vegetables more often, 2) both vegetables and meat or 3) meat more often. Participants were followed up to Dec. 31, 2017. All cancer and eighteen common cancer cases were identified through the code from the International Classification of Diseases, 10th revision. We estimated sexspecific relative risks and 95% confidence intervals, adjusting for age, body mass index, alcohol consumption, smoking, physical activity, and income level. @*Results@#During an average follow-up of 12.4 years, 714,170 cancer cases were documented. In men, consuming meat more often was associated with lower risk of esophageal, liver, and stomach cancers, but higher risk of lung and kidney cancers. Consuming both vegetables and meat was associated with higher risk of prostate cancer, but with lower risk of esophageal, liver, and stomach cancers in men. In women, consuming meat more often was associated with a higher risk of colorectal cancer and breast, endometrial, and cervical cancers diagnosed before the age of 50. Consuming both vegetables and meat was associated with lower risk of liver cancer in women. @*Conclusions@#Our study suggests a potential link between vegetable and meat intake and cancer incidence in the Korean population. Further investigation on the association between the intake of specific types of vegetables and meat and cancer risk in Korean prospective cohort studies is needed.

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

Cancer incidence according to the National Health Information Database in Korean patients withend-stage renal disease receiving hemodialysis

Background/Aims@#The aim of this study was to investigate incidence, survival, and risk factors of cancer in end-stage renal disease (ESRD) patients with hemodialysis using information from the National Health Information Database (NHID). @*Methods@#Using the NHID, we identified ESRD patients who started maintenance hemodialysis between 2003 and 2005 in Korea. Patients were followed from initiation of hemodialysis to renal transplantation, death, or December 31, 2016, whichever came first. We calculated the incidence, survival, and risk factors of cancer. @*Results@#Of the total 14,382 ESRD patients, 1,124 (7.82%; men:women, 728:396) werediagnosed with cancer during follow-up. The mean duration from the start of hemodialysis to new cancer identification was 64.40 ± 41.81 months. Significant risk factors for the development of new cancer were old age, male sex, and liver disease. Conversely, patients with diabetes showed low risk for new cancer. The colorectum (17.31%) was the most common primary site of cancer in men, followed by the liver (15.8%), stomach (14.29%), lung (13.6%), and kidney (10.3%). In women, the colorectum (14.65%) was also the most common primary site of cancer, followed by the breast (12.88%), thyroid (12.63%), stomach (10.86%), and lung (8.08%). According to the primary site of cancer, breast cancer showed the longest median survival duration (130.93 months), followed by thyroid, kidney, colorectum, bladder,stomach, liver, and lung cancer. On multivariate analyses, overall survival was affected by age and diabetes. @*Conclusions@#The cancer incidence of chronic hemodialysis patients was relatively high. Thus, careful monitoring and a specific cancer screening program are needed for chronic hemodialysis patients.

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.

Distribution of working position among workers with varicose veins based on the National Health Insurance and National Employment Insurance data

Background@#This study aimed to determine the effect of specific working postures on the development of varicose veins (VV). By using Korea's National Health Insurance (NHI) and National Employment Insurance (NEI) data, we analyzed the general characteristic and difference in proportions of VV cases according to occupational working posture. @*Methods@#From the NEI and NHI data, participant demographics, such as gender, age, body mass index, and number of workers in specific occupations or industries were obtained.We classified the 240 occupations into blue-collar (BC) and white-collar (WC) occupations and subdivided them into standing, sitting, and walking groups according to the dominant working posture. @*Results@#The number of VV patients per 100,000 individuals increased with age, with a higher number of women than men and a higher number of patients in the BC than WC groups. For the BC group, the proportion of VV cases was the highest in the standing group, followed by the walking and sitting groups, but there was no significant difference between standing and walking groups in man. For the WC group, the standing group had a higher proportion of VV cases than the sitting group, but there was no significant difference between the standing and sitting group in man. In the BC group, the proportion of VV cases was the highest among medical and welfare-related elementary workers, bakers and cookie makers, automobile assemblers, cleaning and guarding-related elemental workers, and nurses and dental hygienists. In the WC group, the proportion of VV cases was the highest among food/ lodging/tourism/entertainment/sports-related managers, environment/cleaning/protective services-related managers, finance and insurance clerks, accounting book-keeping clerks, and social welfare and counseling professionals. @*Conclusions@#This study was performed to determine the characteristics of VV with different working posture among Korean workers. It is expected to be the basis of further studies on occupational musculoskeletal diseases.

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.

Distribution of working position among workers with varicose veins based on the National Health Insurance and National Employment Insurance data

Background@#This study aimed to determine the effect of specific working postures on the development of varicose veins (VV). By using Korea's National Health Insurance (NHI) and National Employment Insurance (NEI) data, we analyzed the general characteristic and difference in proportions of VV cases according to occupational working posture. @*Methods@#From the NEI and NHI data, participant demographics, such as gender, age, body mass index, and number of workers in specific occupations or industries were obtained.We classified the 240 occupations into blue-collar (BC) and white-collar (WC) occupations and subdivided them into standing, sitting, and walking groups according to the dominant working posture. @*Results@#The number of VV patients per 100,000 individuals increased with age, with a higher number of women than men and a higher number of patients in the BC than WC groups. For the BC group, the proportion of VV cases was the highest in the standing group, followed by the walking and sitting groups, but there was no significant difference between standing and walking groups in man. For the WC group, the standing group had a higher proportion of VV cases than the sitting group, but there was no significant difference between the standing and sitting group in man. In the BC group, the proportion of VV cases was the highest among medical and welfare-related elementary workers, bakers and cookie makers, automobile assemblers, cleaning and guarding-related elemental workers, and nurses and dental hygienists. In the WC group, the proportion of VV cases was the highest among food/ lodging/tourism/entertainment/sports-related managers, environment/cleaning/protective services-related managers, finance and insurance clerks, accounting book-keeping clerks, and social welfare and counseling professionals. @*Conclusions@#This study was performed to determine the characteristics of VV with different working posture among Korean workers. It is expected to be the basis of further studies on occupational musculoskeletal diseases.

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.

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.

Job Stress-attributable Burden of Disease in Korea

BACKGROUND: As job stress is associated with various diseases and psychiatric conditions, we aimed to estimate the job stress-attributable burden of disease in Korea based on the concept of disability-adjusted life years (DALY). METHODS: We selected ischemic heart disease (IHD), stroke, major depressive disorder (MDD), and suicide as health outcomes from job stress, because of the ease of access to data estimating burdens and of important meaning of them in Korean occupational background. RESULTS: Our findings demonstrated that approximately 21% of Korean workers were exposed to high job strain, which was attributable for approximately 6.7% of IHDs, 6.9% of strokes, 13.6% of MDDs, and 4% of suicides. In terms of job stress-attributable DALY, the burdens of disease per 100,000 people were 38 for IHD, 72 for stroke, 168 for MDDs, and 44 for suicides. CONCLUSION: The present findings suggested that one-fifth of Korean workers were suffering from high job strain. Although the figures may not be accurate due to several assumptions, job stress is an important risk factor for health in working environment in Korea.

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.