The General Characteristics and Results of the Cold Provocation Test in the Risk Group of HAVS / 대한산업의학회지

OBJECTIVES: The cold provocation test for diagnosing the vascular component in hand-arm vibration syndrome (HAVS) is likely to be accepted as an objective test, and a few studies have been performed. However, controversy has continued regarding the diagnostic performance of this method. Although objective methods such as plethysmography and laser doppler flowmetry have been studied, they have not received as much attention as other diagnostic methods. Therefore, our study aim was to spread the awareness of HAVS by reporting the results of the cold provocation test in a hand-transmitted vibration exposure group. METHODS: The study subjects were 549 workers who had been exposed to hand-transmitted vibrations and reported symptoms in their hands. While the subject immersed both their hands in 10degrees C water for 10 minutes, the skin temperature of 10 fingers was recorded from pre-immersion time to 20 minute postimmersion including 10 minutes immersion time. The recovery rates were calculated from the recorded skin temperatures. The 'decreased recovery rate' criteria were less than 30% at 5 minutes post-immersion and 60% at 10 minute post-immersion. RESULTS: Of the subjects, 69.1% and 30.9% had more severe symptoms in the right and left hands, respectively. The mean finger skin temperature of the right hand after cold-water immersion for 10 minutes was approximately 10degrees C, which increased gradually with time, but they did not reach the baseline temperature at 20 minutes post-immersion. The deviations of the skin temperature in the subjects were higher in the recovery phase than in the baseline and cold immersion phase. The 3rd finger of both hands showed the lowest 5-minute recovery rate among the fingers examined, and the left 4th finger and right 3rd finger showed the lowest 10-minute recovery rate. Of the subjects, 37.6% and 10.4% of subjects showed a lower recovery rate at 5 and 10 minutes in at least one finger, respectively, while 10.2% showed a lower recovery rate at both 5 and 10 minutes simultaneously in at least one finger. CONCLUSIONS: The larger deviations in the recovery phase than in the other phases indicated that interindividual differences are more prominent in the recovery phase. There might be no benefit in observing the finger skin temperature for an additional 10 minutes after 10 minutes post-immersion. Overall, approximately 10% of the subjects in the HAVS risk group had HAVS.

Effect of Hand Transmitted Vibration on the Auditory System / 대한산업의학회지

OBJECTIVES: This study was undertaken to estimate the effect of hand transmitted vibration exposure for long time period on the auditory system in shipyard grinder workers. METHODS: From 2006 to 2009, the study was carried out on 87 grinder workers for hand transmitted vibration exposure group, with 81 welders who were served as the control group. All subjects were male; at baseline, none of the participants had ear disease or diabetes mellitus. Auditory threshold at different frequencies ranged from 0.25 kHz to 8 kHz for both ear was recorded; the following were also collected from the subjects: age, exposure duration, noise exposure level of investigation year, total cholesterol, systolic/diastolic blood pressure, and smoking history. RESULTS: In comparison of two groups, mean of age, exposure duration, noise level, total cholesterol, systolic/diastolic blood pressure, smoking rate were not significantly different between the groups. Auditory thresholds of 0.25, 0.5 kHz frequencies in both ear, 1 kHz frequency in right ear, and 8 kHz frequency in left ear were higher in hand-transmitted vibration exposure group than that in the control group at a statistically significant level. After stratification by age 50 years, there were no significant differences between the two groups in less than 50-years old age group, but auditory threshold of 0.25, 0.5, 1 and 8 kHz frequency were significantly different between the two groups in above 50-years old age group. The differences between two groups ranged from 0.4 dB(HL) to 6.7 dB(HL). Multiple linear regression analysis showed that hand transmitted vibration exposure was significant only in 0.25, 0.5 kHz frequency and the regression coefficients of vibration exposure ranged from 3.826 to 5.028 in those frequencies. CONCLUSIONS: The differences of hearing threshold between two groups only in the 50-years old group were possibly owing to changed peripheral vascular system with autonomic nervous system, and significances only in low frequencies such as 0.25, 0.5 kHz probably mean that hand vibration exposure have been transmitted to auditory organ over long term. Collectively, older people can be more susceptible to hearing loss in the presence of hand transmitted vibration exposure and auditory threshold at low frequency may be more affected by the hand transmitted vibration exposure than high frequency.

Two Case of Erythroleukemia and Myelodysplastic Syndrome in a Non-Destructive Inspector / 대한산업의학회지

BACKGROUND: Ionizing radiation is a group 1 carcinogen according to the IARC(International Agency for Research on Cancer) classification. With the development of the radiation related industry, the number of radiation exposed workers has been increasing. There have been several reports on AML(Acute Myeloid Leukemia) on exposure to ionizing radiation; however, there are no reports of occupational malignant lymphohematopoietic disease related to non-destructive inspection. CASE REPORT 1: A 35-years-old male, who had worked for 10 years in non-destructive inspection, was diagnosed with myelodysplastic syndrome. He worked 8 hours a day, for three weeks per months, where he was exposed to 192Ir and 60Co radiation sources. Because he had not worn a film badge for monitoring his radiation exposure dose, the accurate exposure dose was not reported. The estimate exposure dose calculated via a chromosomal study was 1.20 Gy, which exceed the dose limits of Korean radiation dose standards, which are 50 and 100 mSv annually and quinquennially respectively. CASE REPORT 2: A 26-years-old male, who had worked for 2.5 years in the same company was also diagnosed with myelodysplastic syndrome. CONCLUSION: Non-destructive inspection is the main source of ionizing radiation in the workplace, which could be the cause of malignant lymphohematopoietic diseases. Therefore, more practical plans and guidelines are needed to prevent non-destructive inspectors from workplace radiation exposure.

Seroprevalence of Hepatitis A in a Manufacture Workplace / 대한산업의학회지

OBJECTIVES: The prevalence of hepatitis A decreases with improved hygiene and changing lifestyle. However, hepatitis A remains a global problem causing sporadic food-borne infections. Over the past 5 years, hepatitis A incidence has increased, and 15 deaths were reported in 2009 in Korea. Concerns about hepatitis A infection have increased. We checked hepatitis A virus antibody (HAV anti-IgG) in a large manufacturing company, so that the results could be a guideline for workplace preventive plan and health policy for hepatitis A. METHODS: We investigated the seroprevalence of HAV anti-IgG and the demographic characteristics of employee volunteer, in a company in Ulsan. In addition, we estimated those factors that affected seroprevalence of HAV anti-IgG. RESULTS: A total of 2,719 employee volunteers were enrolled into the study. The seropositive rate of HAV anti-IgG was 69.8% (n=1,899) and, the seronegative rate was 30.2% (n=820). There were no enrolled employees under age 24 years who tested positive for HAV anti-IgG; in this group, the seropositive rate was 0.0% (n=0); in 25~29 years the rate was 3.9% (n=12) and 26.5% (n=118) in 30~34 years olds. In the 35-39 ears, 61.1% (n=203) tested HAV anti-IgG positive and 86.8% (n=256) of 40~44 years tested positive. Other group tested as follows: 96.5% (n=335) in 45~49 year olds, 98.7% (n=593) in 50~54 year olds, and 100% (n=382) in over 55 years. There was a significantly increasing tendency to test HAV anti-IgG positive according to age group. In the 34-35 year olds, the seropositive rate exceeded the seronegative rate. CONCLUSIONS: HAV anti-IgG seropositive rate increased according to age. The result can used for guideline recommendationsand establishing hepatitis A policies.