The Relationship of Liver Function Tests to Mixed Exposure to Lead and Organic Solvents

OBJECTIVE: This study aims to compare liver function indices (aspartate aminotransferase [AST], alanine aminotransferase [ALT], and gamma glutamyl transferase [GGT]) among males who work with lead, organic solvents, or both lead and organic solvents, under the permissible exposure limit (PEL). METHODS: A total of 593 (out of 2,218) male workers who agreed to share their personal health information for medical research were selected for this study. Those excluded were hepatitis B carriers, individuals exposed to occupational risk factors other than lead and organic solvents, and individuals without liver function results. The 593 were divided into five groups: a lead-exposed group, an organic solvent-exposed group exposed to trichloroethylene (TCE co-exposed solvent group), an organic solvent-exposed group not exposed to trichloroethylene (TCE non-exposed solvent group), a lead and organic solvent-exposed group (mixed exposure group), and a non-exposed group (control group). We performed a one way-analysis of variance (one way-ANOVA) test to compare the geometric means of liver function indices among the groups, using a general linear model (GLM) to adjust for age, work duration, body mass index (BMI), smoking, and alcohol intake. In addition, we performed a binary logistic regression analysis to compare the odds ratios among groups with an abnormal liver function index, according to a cut-off value. RESULTS: The ALT and AST of the mixed exposure group were higher than those of the other groups. The GGT of the mixed exposure group was higher than the TCE co-exposed solvent group, but there was no difference among the control group, TCE non-exposed solvent group, lead-exposed group, and mixed exposure group. The same result was evident after adjusting by GLM for age, work duration, BMI, smoking, and alcohol intake, except that ALT from the mixed exposure group showed no difference from the TCE co-exposed solvent group. When the cut-off values of the AST, ALT, and GGT were 40 IU/L, 42 IU/L, and 63 IU/L, respectively, a logistic regression analysis showed no differences in the odds ratios of those who had an abnormal liver function index among the groups. However, if the cut-off values of the AST, ALT, and GGT were 30 IU/L, 30 IU/L, and 40 IU/L, respectively, the odds ratio of the AST in the mixed exposure group was 4.39 (95% CI 1.86-10.40) times higher than the control. CONCLUSION: This study indicates that a mixed exposure to lead and organic solvents is dangerous, even if each single exposure is safe under the permissible exposure limit. Therefore, to ensure occupational health and safety in industry, a continuous efforts to study the effects from exposure to mixed chemicals is needed.

Relationship of Aircraft-noise and the Result of Audiological Evaluation Among Residents Near U.S. Military Airbases in Pyeongtaek City / 대한산업의학회지

Objective: To investigate the relationship between aircraft noise and the results of audiological evaluation on tinnitus and hearing loss among residents near United States military air-bases in Pyeongtaek city. METHODS: Residents (n=492) exposed to aircraft noise were selected from eight villages near U.S. military air-bases (K-55 and K-6) in Pyeongtaek city. Residents (n=200) from five villages located at least 10 km away from the air-base were selected for the control group. All participants completed a questionnaire on tinnitus and audiological evaluations included pure tone audiometry (PTA) and distortion product otoacoustic emissions (DPOAE). Statistical analyses involved a general linear model and multiple logistic regression stratified by gender and data was adjusted by age, educational level, stress response index and noise type (i.e. military, agricultural and occupational). RESULTS: The equivalent noise levels (Leq) in the vicinity of the air-field were 73.4~81.5 dB (A). Tinnitus prevalence was 47.3% and odds ratio (OR) was 2.06 (95% confidence interval (CI): 1.09~3.88) among noise-exposed males. Tinnitus prevalence was 50.8% and OR was 1.97(95% CI: 1.17~3.30) among noise-exposed females. Tinnitus handicap scores among exposed group were significantly higher in functional, emotional, and catastrophic subclasses (p<0.001). PTA revealed hearing thresholds among the exposed group of 0.5 and 1 kHz (male right ear), 0.5 and 1 kHz (female left ear) and 0.5, 1, 2, 3, 4 and 6 kHz on female right ear that were significantly higher than those of the unexposed group. No significant difference in DPOAE was observed among noise-exposed males. However, significant differences were evident for noise-exposed females at 3175 and 4007 Hz. ORs of right female ears 3175 and 4007 Hz were 1.73(95% CI: 1.01~2.99) and 1.78(95% CI: 1.01~3.15). ORs of left female ears at 3175 Hz and 4007 Hz were 1.92(95% CI: 1.10~3.36) and 2.71(95% CI: 1.49~4.91) CONCLUSIONS: Aircraft noise may adversely affect hearing function and tinnitus.

Relationship of Aircraft-noise and the Result of Audiological Evaluation Among Residents Near U.S. Military Airbases in Pyeongtaek City / 대한산업의학회지

Objective: To investigate the relationship between aircraft noise and the results of audiological evaluation on tinnitus and hearing loss among residents near United States military air-bases in Pyeongtaek city. METHODS: Residents (n=492) exposed to aircraft noise were selected from eight villages near U.S. military air-bases (K-55 and K-6) in Pyeongtaek city. Residents (n=200) from five villages located at least 10 km away from the air-base were selected for the control group. All participants completed a questionnaire on tinnitus and audiological evaluations included pure tone audiometry (PTA) and distortion product otoacoustic emissions (DPOAE). Statistical analyses involved a general linear model and multiple logistic regression stratified by gender and data was adjusted by age, educational level, stress response index and noise type (i.e. military, agricultural and occupational). RESULTS: The equivalent noise levels (Leq) in the vicinity of the air-field were 73.4~81.5 dB (A). Tinnitus prevalence was 47.3% and odds ratio (OR) was 2.06 (95% confidence interval (CI): 1.09~3.88) among noise-exposed males. Tinnitus prevalence was 50.8% and OR was 1.97(95% CI: 1.17~3.30) among noise-exposed females. Tinnitus handicap scores among exposed group were significantly higher in functional, emotional, and catastrophic subclasses (p<0.001). PTA revealed hearing thresholds among the exposed group of 0.5 and 1 kHz (male right ear), 0.5 and 1 kHz (female left ear) and 0.5, 1, 2, 3, 4 and 6 kHz on female right ear that were significantly higher than those of the unexposed group. No significant difference in DPOAE was observed among noise-exposed males. However, significant differences were evident for noise-exposed females at 3175 and 4007 Hz. ORs of right female ears 3175 and 4007 Hz were 1.73(95% CI: 1.01~2.99) and 1.78(95% CI: 1.01~3.15). ORs of left female ears at 3175 Hz and 4007 Hz were 1.92(95% CI: 1.10~3.36) and 2.71(95% CI: 1.49~4.91) CONCLUSIONS: Aircraft noise may adversely affect hearing function and tinnitus.

Effects of Cardiovascular Risk Factors on Hearing Loss / 대한산업의학회지

OBJECTIVE: To investigate the effects of cardiovascular risk factors on hearing loss by vascular damage, such as in atherosclerosis. METHOD: This study was conducted as a part of a study for the health effects of air-craft noise from 13 July 2005 to 13 January 2006. In this study 810 residents were selected from 13 villages in Pyeongteck City. Participants in this study were stratified by gender. Individuals, who had conductive hearing loss, were excluded form this investigation. Cardiovascular risk factors were divided into medical risk factors (mean arterial pressure (MAP), blood glucose, triglyceride) and behavioral risk factors (smoking, alcohol). The degree of atherosclerosis was determined by aPWV. Pure tone air conduction hearing thresholds were obtained at frequencies of 1000 and 4000 Hz. As for statistic data analysis, multiple linear regression models were used to evaluate the relationship between factors on hearing loss and aortic pulse wave velocity. Structural Equation Modeling was used to analyze the relationship between factors. RESULTS: According to multiple linear regression models among males, age, aircraft noise, aPWV were associated with hearing loss. In females, age and aircraft noise were associated with hearing loss. Thus cardiovascular risk factors were not directly involved in hearing loss. However, cardiovascular risk factors such as alcohol, MAP in males and MAP, blood glucose in females were statistically significant (p<0.05) on aPWV according to multiple linear regression modeling. According to analysis of structural equation modeling, an indirect relationship was observed between cardiovascular risk factors and hearing loss by atherosclerosis, which was measured by aPWV. In males, medical risk factors were significantly associated with atherosclerosis (beta+/-SE: 0.07+/-0.03, p=0.03). Atherosclerosis was also associated with hearing loss (beta+/-SE: 2.01+/-0.89, p=0.03). In females, medial risk factors was significantly associated with atherosclerosis (beta+/-SE: 0.08+/-0.02, p=0.00), but atherosclerosis was not significantly associated with hearing loss. CONCLUSION: Although noise exposure is a known major threat to hearing loss, understanding of cardiovascular risk factors associated with hearing loss also take a significant role in preventing hearing loss. Therefore, scrutinization of the etiologic factors for hearing disability may introduce a detailed strategy to abate the prevalence of hearing loss.

Cervical HIVD Related to Long-Term Whole Body Vibration and Awkward Posture / 대한산업의학회지

BACKGROUND: The relationship between whole body vibration and awkward neck posture to cervical herniated intervertebral disc (HIVD) has been rarely reported. In this report, we present the case of an overhead crane operator, that had no known history of neck injury, but had long-term exposure to whole body vibration and improper neck posture, who developed cervical HIVD, which raises concerns over the possibility of occupational causation. CASE: A patient, operating an overhead crane since Dec 26th 1986, began to suffer from a neck pain and developed cervical HIVD in 1998. He had been frequently treated in an outpatient clinic, but the symptom was not improve. Eventually, he got HIVD surgery in Sep 6th 2007, and then the symptom was relieved. There were 4 groups and 3 shift system in the patient's overhead crane operation. He worked eight hours a day and 5 days a week. Actual crane work time was about 6 hours a day. The crane was located at 20 meters above the work field so that the crane operator had to look downward and the neck was bent by more than 20degrees for nearly the entire working day. Daily vibration exposure was expressed in terms of an 8-hour energy-equivalent frequency-weighted acceleration magnitude (A(8)) and vibration dose value (VDV). The daily A(8) was measured to be 0.23 m/s2 and the daily VDV was 7.4 m/s(1.75). Although these levels were below the action level recommended by the International Organization for Standardization (ISO) and European Commission (EC), it cannot be ignored that whole body vibration in addition to an awkward neck posture may be related to an increased risk for neck disease. A long-term awkward posture can adversely impact the prevalence of neck disease. In addition, occupational exposure to whole body vibration along with an awkward neck posture seems to exacerbate these effects. CONCLUSION: An overhead crane operator may have acquired cervical HIVD due to an occupational causation. Therefore, to elucidate the causal relationship of an improper neck posture and whole body vibration to neck diseases, further investigations need to be conducted for lager sample of overhead crane operators that were exposed to a long-term awkward neck posture and whole body vibration.

Clinical Review of Acute Mesenteric Ischemia

PURPOSE: The purpose of this study was to review our clinical experiences of acute mesenteric ischemic disease at the Masan Samsung hospital. METHOD: Retrospectively reviewed the medical records of 20 patients with acute mesenteric ischemic disease from 1998 through 2003 in terms of clinical characteristics, image findings, management and results. RESULT: The mean age of patients was 63.5 years and the male female ratio was 1.5:1. Coexisting diseases were atrial fibrillation (n=10), hypertension (n=9), myocardial infarction (n=2), DM (n=4). The clinical manifestations were abdominal pain, abdominal distension, peritoneal irritation signs, vomiting and melena. The presenting signs were nonspecific. Laboratory findings were nonspecific and not helpful for diagnosis of acute mesenteric ischemia. Abdominal CT and SMA angiography were accurate and sensitive diagnostic tools. Seventeen cases were SMA occlusion (1 case: SMA dissection) and 3 cases were SMV occlusion. Operative procedures were resection of bowel (12 cases) and thromboembolectomy (5 cases). Non operative procedure was anticoagulation (3 cases). One patient refused surgery. CONCLUSION: Both clinical and laboratory data were non-specific and delayed diagnosis was the main cause of the overall mortality rate of 35% (7 cases). The mortality rate for patients undergoing surgery for acute mesenteric ischemic disease was high, but early diagnosis and intensive care may be reduced mortality.