Cohort study for the effect of chronic noise exposure on blood pressure among male workers in Busan, Korea.

OBJECTIVE: It has not yet been established whether exposure to chronic noise induces an increase in blood pressure or an increase in the development of hypertension. Therefore, a cohort study was performed to identify the effects of chronic noise exposure on blood pressure. METHODS: Five hundred thirty male workers at a metal manufacturing factory in Busan, Korea, were enrolled in the study. They were monitored with an annual health check-ups for nine consecutive years from 1991 to 1999. The subjects were divided into four groups which were determined by noise level categories (NLCs) according to the exposure of noise intensity; NLC-I: office workers who were exposed to <60 dBA at work; NLC-II: worksite technical supporters or inspectors who were intermittently exposed to noise and were not using hearing protection devices; NLC-III: worksite workers exposed to a noise below 85 dBA (TWA) and used one type of hearing protection device, earplug or earmuff; NLC-IV: worksite workers who were exposed to a noise level of 85 dBA or higher in average and used both earplug and earmuff. RESULTS: After controlling the possible confounders, such as baseline age, smoking, alcohol intake, exercise, family history of hypertension, systolic blood pressure (SBP), or diastolic blood pressure (DBP), and changes in body mass index (BMI), we determined that the mean values for the SBP over the duration of this study were 3.8, 2.0, and 1.7 mmHg higher in groups NLC-IV, NLC-III, and NLC-II, respectively, in comparison to that of the NLC-I group. There was no significant difference in DBP among the groups. CONCLUSION: This study suggests that chronic noise exposure increases SBP independently, among male workers.

High pallidal T1 signal is rarely observed in obstructive jaundice, but is frequently observed in liver cirrhosis.

Although high signal intensities in the globus pallidus are frequently observed in T1-weighted magnetic resonance images (MRI) of patients with liver cirrhosis, it is unclear whether these increases are due to portal-systemic shunt or obstruction of biliary excretion. We therefore studied pallidal signals in 18 cancer patients with bile duct obstruction and marked jaundice (>10 mg/dl). Patients who had fever, leukocytosis or liver cirrhosis were excluded to ensure that jaundice was due to bile duct obstruction. All patients showed a dilated intrahepatic duct on computed tomography (CT) scan. A high pallidal signal was observed in one of 18 biliary obstructive patients whereas high signals were highly prevalent in liver cirrhosis. A portal-systemic shunt rather than an obstruction of biliary excretion may be responsible for the increased blood manganese concentrations and pallidal T1 signals in chronic liver diseases.