The Relationship between Shift Work and Work-related Injuries among Korean Workers / 대한산업의학회지

OBJECTIVES: The aim of this study was to evaluate the relationship between shift work and work-related injuries in a representative sample of Korean workers. METHODS: We used data from the Korean Working Condition Survey of 2006. The participants were 7,075 Korean workers 15 to 64 years of age. Logistic regression was employed to estimate the relationship between shift work and work-related injury using the SAS version 9.2 program. RESULTS: Shift work was significantly related to work-related injuries compared to non-shift workers(OR 2.40, 95% CI=1.65~3.48). When personal and occupational risk factors were accounted for, shift work had a statistically meaningful relationship with work-related injuries compared to non-shift work(OR 1.79, 95% CI=1.20~2.66). CONCLUSIONS: In this study, shift workers appear to have a higher risk of work-related injuries compared to non-shift workers. Work-related injuries in shift workers could be attributed to circadian rhythm disorder and sleep problems. Suitable arrangements that ensure flexible working times are needed for shift workers. Further study will be needed to identify and mitigate work-related injuries among shift workers.

Relationship between Workplace Physical and Chemical Hazard Exposures and Mental Health Problems in Korea / 대한산업의학회지

OBJECTIVES: Mental health and work efficiency are adversely affected by exposure to physical and chemical hazards in the workplace. This study is the first large scale evaluation of the relationship between physical and chemical hazard exposure in the workplace in relation to the mental health of Korean workers. METHODS: A national survey of a random sample of workers (n=10,043) was conducted between June and September 2006 in Korea. Physical and chemical hazards in the workplace were considered if exposure occurred over more than a quarter of the time spent at work. Mental health problems were defined as work-related depression, anxiety or insomnia. We analyzed whether physical and chemical hazards were independent risk factors for work-related mental health problems by multiple logistic regression analysis after adjusting for age, gender, employment type, education, occupation, duty schedule, work hours, smoking, and alcohol consumption. RESULTS: The mean age of surveyed workers was 42 years and 58% were male. A total of 7.8% of workers had work-related mental health problems. Exposure to high temperature, mist, fumes, dust, chemicals, and radiation were associated with an increased risk of work-related mental health problems. CONCLUSIONS: This study reaffirmed that physical and chemical hazard exposure in the workplace significantly elevates the risk of work-related mental health problems.

The Health Effects of Mercury on the Cardiac Autonomic Activity According to the Heart Rate Variability / 대한산업의학회지

OBJECTIVES: The effect of mercury on the cardiovascular system has recently been reported on, but the mechanisms as well as its nature of this effect still need to be confirmed. In this study, the mercury in the hair of a community population was analyzed in relation to the cardiac autonomic activity. METHODS: A hair sample was obtained from the occiput area and the mercury in the hair was analyzed by using a Direct Mercury Analyzer. We measured the cardiovascular risk factors, including total cholesterol, triglyceride, blood pressure, and the body mass index (BMI). Heart rate variability was assessed for 5 minutes, in the time and frequency domain, by using SA-3000P from the Medi-core(R). company. The association between the mercury in the hair and heart rate variability was assessed after controlling for the other cardiovascular risk factors. RESULTS: The mean age of the 671 total subjects was 36 years. The geometric mean of the hair mercury was 0.90 ppm. The hair mercury level was elevated in males, adults, smokers and drinkers. Hair mercury and age, the systolic and diastolic blood pressure, total cholesterol, triglyceride, LDL cholesterol and BMI were all positively correlated. However, hair mercury and heart rate, HDL cholesterol, standard deviation of the NN intervals (SDNN), total power (TP), low-frequency (LF), high- frequency (HF) were negatively correlated. In the higher mercury group, heart rate, SDNN, LF and HF indices were significantly lower compared with those of the lower mercury group. Heart rate was decreased 2.6 beats/min, Ln (HF) was decreased 0.131 msec2 and HF norm was decreased 2.550 with a 1 ppm increase of Ln (Hg), according to multiple linear regression analysis after controlling for age, gender and other cardiovascular risk factors. CONCLUSION: This cross-sectional study showed that mercury may affect the cardiac autonomic activity through parasympathetic dysfunction.