Working Hours and Cardiovascular Disease in Korean Workers: A Case‐control Study: Inchul JEONG, et al. Graduate School of Public Health, Yonsei University, Republic of Korea—Objectives: Long working hours can negatively impact a worker's health. The objective of this study was to examine the association between working hours and cardiovascular diseases (CVDs) and compare the degree of risk based on CVD subtypes in Korean workers.Methods: This study was a case‐control study of the patients registered in the Occupational Cardiovascular Diseases Surveillance 2010. The cases included 348 patients diagnosed with a CVD (123 cerebral infarction, 69 intracerebral hemorrhage, 57 subarachnoid hemorrhage, 99 acute myocardial infarction). Controls were 769 participants with no history of CVDs matched for gender, age, type of occupation, and region. Participants' working hours in the previous week and the average working hours over the past three months were assessed to examine short‐term and long‐term effects.Results: After adjusting for confounding factors, the odds ratios (ORs) for CVDs in the short‐term were 2.66 (95% Confidence interval (CI) :1.78−3.99) for working ≤40 hours, 1.85 (95% CI: 1.22−2.81) for working 50.1−60 hours and 4.23 (95% CI: 2.81−6.39) for working >60 hours compared with the 40.1−50‐hour working group. The ORs in the long‐term were 2.90 (95% CI: 1.86−4.52) for working ≤40 hours, 1.73 (95% CI: 1.03−2.90) for working 48.1−52 hours and 3.46 (95% CI: 2.38−5.03) for working >52 hours compared with the 40.1−48‐hour working group.Conclusions: Long working hours are related to an increased risk of CVDs, and the degree of risk differs based on CVD subtype. Short working hours are also related to an increased risk for CVDs. More prospective studies targeting specific disease risks are required.

Park J, et al. Ann Occup Environ Med. 2019 Oct;31(1):e27. https://doi.org/10.35371/aoem.2019.31.e27

While exposure to sunlight is a well-documented primary source of vitamin D supply, factors leading to vitamin D deficiency vary according to population characteristics. Using nationwide data from the Korea National Health and Nutrition Examination Survey (KNHANES), we aimed to investigate a diverse range of potential factors in association with vitamin D deficiency. Overall, 21,208 participants aged ≥20 years were selected from KNHANES conducted between 2010 and 2014. The associations between various environmental and occupational factors and vitamin D deficiency (defined as serum 25-hydroxyvitamin D [25(OH)D] < 20 ng/mL) were evaluated in logistic regression models after controlling for potential covariates and also after stratification for age and sex. Under given criteria, 15,138 (71.4%) participants were vitamin D deficient. Significant associations were observed between vitamin D deficiency and average environmental temperature and radiation, weekly walking frequency, type of occupation, and shift work. When participants were stratified by age and sex, we observed greater associations of vitamin D deficiency with walking frequency among young males (odds ratio [OR] and 95% confidence interval [95% CI]: 1.24 [1.05–1.47] for those walking <5 times per week compared to those walking ≥5 times per week) and shift work (OR [95% CI]: 1.40 [1.10–1.78] for those working at night compared to those working during the day). We also observed a significant association of vitamin D deficiency with educational attainment (OR [95% CI]: 1.43 [1.09–1.89] for those with ≤middle school compared to those with ≥high school) among older group of females. This study suggests that vitamin D deficiency is related to geographical conditions and subpopulation characteristics. The age and sex-specific associations may urge the effective promotion of vitamin D supply recommendations.

Peripheral neuritis caused by acrylamide is well-known, and many Korean grouting workers are frequently exposed to acrylamide in grouting agents that are injected into cracked concrete. We recently encountered two cases of dermal and neural toxicity in Korean grouting workers with exposure to grouting agents that contained a high concentration of acrylamide. The first case involved a 44-year-old man with 8 years of waterproofing experience. The patient developed peeling skin on both hands while grouting, which progressed to systemic neurological symptoms, such as reduced sensory function and strength. The patient was diagnosed with peripheral neuropathy caused by acrylamide exposure, and fully recovered after conservative treatment and withdrawal of exposure to the grouting agent. The second case involved a 34-year-old man with 10 years of grouting experience. The patient initially experienced weakness in both legs, which progressed to weakness in his arms and uncontrolled phonation. After being hospitalized, he was diagnosed with cerebellar ataxia and peripheral neuropathy caused by acrylamide exposure, and was discharged after conservative treatment. Our follow-up investigation revealed that both workers were recently exposed to grouting agents that contained higher concentrations of acrylamide, compared to the agents that they had previously been using. Both workers had workplace acrylamide exposure through dermal contact plus inhalation of dust and vapor, which led to the neural toxicity and dermatitis. Therefore, government studies are needed to investigate the current status of workplace acrylamide use, and to protect workers from the hazardous effects of using acrylamide-containing grouting agents.

This study aimed to identify work-related risk factors, including long working hours and night/shift work, for unmet health care need using data of a representative panel of Korean adults. Associations between work-related factors and unmet health care need were analyzed using data of 3,440 participants (10,320 observations) from the 2011-2013 Korean Health Panel Study. A generalized estimating equation was used for the analysis of repeated measures. The prevalence of unmet health care was 16.6%. After adjusting sex, age, socioeconomic status, work characteristics, and working more than 60 hours per week (odds ratio [OR]: 1.43, 95% confidence interval [CI]: 1.23–1.65) or 50–59 hours per week (OR: 1.26, 95% CI: 1.08–1.46) instead of 40–49 hours per week and night/shift work (OR: 1.27, 95% CI: 1.06–1.51) were associated with unmet health care need. Long working hours and night/shift work are risk factors for unmet health care need among the Korean working population.

Kim I, et al. J Korean Med Sci. 2012 May;27(Suppl):S47-S54. http://dx.doi.org/10.3346/jkms.2012.27.S.S47