Journal of Preventive Medicine and Public Health

Volume 34(2); May 2001

Original Articles

Health Effects of Ambient Particulate Pollutants.: Yun Chul Hong, Soo Hun Cho; Korean J Prev Med. 2001;34(2):103-108.

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Abstract PDF: Recently, numerous studies have focused on the health effects of ambient particulate pollutants. Compared to earlier studies that focused on severe air pollution episodes, recent studies are more relevant to understanding the health effects of air pollution at levels common to contemporary cities. We reviewed recent epidemiologic studies that evaluated health effects of particulate air pollution and concluded that respirable particulate air pollution is an important contributing factor to acute mortality and morbidity. We observed increased respiratory and cardiovascular deaths, increased hospital admissions and visits, and decreased lung function. We also observed increased mortality and morbidity in a Korean population. Theses health effects were observed at levels below the current Ambient Air Quality Standard for particulate air pollution.; Summary

Issues in Air Pollution Epidemiologic Studies.: Eun Hee Ha, Ho Jang Kwon; Korean J Prev Med. 2001;34(2):109-118.

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Abstract PDF: The purpose of this review is to discuss the debate concerning the interpretation of epidemiologic studies on particles and health effects. Study of the 1952 air pollution disaster in London established that very high levels of particulate-based smog can cause dramatic increases in daily mortality. However, recent epidemiologic studies have reported statistically significant health effects and mortality due to low levels of air pollution. The statistical significance does not prove causation in observational studies; therefore it is necessary to evaluate these associations. There are arguments for and against each of the numerous studies using Hill's criteria, however the body of accepted evidence supports the causal association. In particular, a high level of consistency in the estimated effect of PM10 has been observed across studies worldwide. The mechanism of the relationship between air pollution and health effects is not obvious. The mechanism of particle-induced injury may involve the production of an inflammatory response by the particulate. The harvesting and the threshold effect are also major concerns regarding the health effects of air pollution. However, current epidemiologic findings indicate that linear models lacking a threshold are appropriate for assessing the effect of particulate air pollution on daily mortality even at current levels.; Summary

Epidemiologic Methods and Study Designs for Investigating Adverse Health Effects of Ambient Air Pollution.: Jong Tae Lee, Ho Kim; Korean J Prev Med. 2001;34(2):119-126.

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Abstract PDF: Air pollution epidemiologic studies are intrinsically difficult because the expected effect size at general environmental levels is small, exposure and misclassification of exposure are common, and exposure is not selective to a specific pollutant. In this review paper, epidemiologic study designs and analytic methods are described, and two nationwide projects on air pollution epidemiology are introduced. This paper also demonstrates that possible confounding issues in time-series analysis can be resolved and the impact on the use of data from ambient monitoring stations may not be critical. In this paper we provide a basic understanding of the types of air pollution epidemiologic study designs that be subdivided by the mode of air pollution effects on human health (acute or chronic). With the improvements in the area of air pollution epidemiologic studies, we should emphasize that elaborate models and statistical techniques cannot compensate for inadequate study design or poor data collection.; Summary

Separate and Combined Effect of Cadmium and Nickel on Blood Pressure in Rats.: Seung Jun Wang, Bong Suk Cha; Korean J Prev Med. 2001;34(2):127-130.

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Abstract PDF: OBJECTIVE
To verify the separate and combined effects of cadmium and nickel on blood pressure in rats. METHODS: Following the daily administration of cadmium chloride(CdCl2) and nickel chloride(NiCl2) to rats both individually and in combination with intraperitoneal injection method for one week, systolic blood pressure of the tail was measured at 1 day and 5, 10, 20, 30 days after administration. Each substance was injected into the rats with 0.1 mg/kg bw and 1.0 mg/kg bw concentration. RESULTS: After 0.1 mg/kg bw CdCl2 was injected, a statistically significant difference was found as compared with the control group(only saline) after 1, 5 and 10 days. After 0.1 mg/kg bw NiCl2 was injected, a statistically significant difference was not found compared with the control group. After 0.1 mg/kg bw CdCl2 and 0.1 mg/kg bw NiCl2 were injected simultaneously, a statistically significant difference was found as compared with the control group after 1, 5 and 10 days and compared with 0.1 mg/kg bw CdCl2 group after 5 days and as compared with 0.1 mg/kg bw NiCl2 group after 5 and 10 days. After 1.0 mg/kg bw CdCl2 was injected, a statistically significant difference was found as compared with the control group after 1, 5, 10 and 20 days. After 1.0 mg/kg bw NiCl2 was injected, a statistically significant difference was found as compared with the control group after 1 day and 5 days. After 1.0 mg/kg bw CdCl2 and 1.0 mg/kg bw NiCl2 were injected in combination, a statistically significant difference was found after 1, 5, 10, 20 and 30 days as compared with 1.0 mg/kg bw CdCl2 after 10, 20 and 30 days and as compared with 1.0 mg/kg bw NiCl2 after 5, 10, 20 and 30 days. CONCLUSION: It was found that the effect of CdCl2 on blood pressure was much more than NiCl2 and a high concentration CdCl2 and NiCl2 in combination delayed the recovery of blood pressure.; Summary

Comparative Epidemiologic Survey of Measles in Two Primary Schools.: Sue Kyung Park, Jee Hee Kim, Joo Yeon Lee, Byoung Kuk Na, Woo Joo Kim, Hae Kwan Cheong; Korean J Prev Med. 2001;34(2):131-140.

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Abstract PDF: OBJECTIVES
During March-May, 2000, a measles outbreak occurred at Youngduk, Korea. This county is divided into two areas with different historical and socioeconomic background. The outbreak occurred in one of these areas. We conducted a comparative epidemiologic study on the two areas in order to evaluate the factors related to the epidemic. MATERIALS AND METHODS: We selected two groups, grades 3 and 5 in a primary schools in each area. We investigated outbreak-related factors using parent-questionnaires, the vaccination history from the students health record and the records concerning the recent measles-outbreak from the local health center. Serologic test on measles-IgG and -IgM antibody was done. RESULTS: The infection rate was 31.6% for the epidemic area and 3.7% for non-the epidemic area according to clinical or serological criteria (p<0.001). No difference was seen in the measles vaccination rate, residence at the time of vaccination or past measles infection history between the two areas. In the epidemic area, the attack rate for the 4-6 year-old MMR booster group(20.5%) was higher than the non-booster group(32.4%), but was not found significantly. Vaccine efficacy was 29.6% in the epidemic area and 87.0% in the non-epidemic area (p<0.001). The IgG level and positive rate were significantly different between the two areas (median 10727 IU/ml, 98.9% in epidemic area; median 346 IU/ml, 85.9% in the non-epidemic area, p<0.001). However, the IgG level and positive rate between the measles-cases and non-cases were not significantly different. CONCLUSIONS: This outbreak took place in mostly vaccinated children. These results suggest that a reduction of herd immunity for immunity failure after vaccination may be one of the feasible factors related to the outbreak pattern in the two areas. The results of the IgG level and positive rate suggest that re-establishment of a normal value for IgG level and of a qualitative method for IgG are needed.; Summary

Job Stress and Its Related Factors in South Korean Doctors.: Yune Sik Kang, Sin Kam, Sang Won Lee, Byung Yeol Chun, Min Hae Yeh; Korean J Prev Med. 2001;34(2):141-148.

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Abstract PDF: OBJECTIVE
To investigate the sources, extent and related factors in South Korean doctors. METHODS: The study subjects were 934 doctors in Taegu, Kyungpook Province, Korea(540 independent practitioners, 105 employed at hospitals and 289 residents in training). Information concerning job stress was obtained using a 9-item questionnaire. Information regarding related factors such as demographic characteristics(age, sex, marital status), perceptions on the socioeconomic status of doctors and working conditions(work time, on-call days per week) was also obtained by self-administered questionnaire during April and May, 2000. RESULTS: Major sources of job stress included clnical responsibility/judgement factor, patient factor and work loading factor. The job stress score of residents was the highest among three groups. The score was lower in older doctors. The score was low among those who thought doctors socioeconomic status was not good. The longer the work time, the higher the job stress score was. Multiple regression analysis was conducted to control for the mutual influence of independent variables. In regression analysis, the score of residents was higher than practitioners. Work time and socioeconomic status perception had negative effects on job stress score. CONCLUSION: The average job stress score of the doctors was high. Age, work type, working conditions and perceptions of socioeconomic status were found to besignificantly related to job stress score. Although the job stress of doctors is somewhat inevitable due to the nature of the doctor's job, control of work time, development of coping tools and other intervention methods are needed to reduce job stress of doctors. Further studies are required to understand the characteristics of job stress and reduce the job stress of doctors.; Summary

A Nested Case Control Study on Risk Factors for Coronary Heart Disease in Korean.: Ki Soon Kim, So Yeon Ryu, Jong Park, Jong Ku Park, Chun Bae Kim, Byung Yeol Chun, Tae Yong Lee, Kang Sook Lee, Duk Hee Lee, Kwang Wook Koh, Sun Ha Jee, Il Suh; Korean J Prev Med. 2001;34(2):149-156.

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Abstract PDF: OBJECTIVE
To elucidate risk factors for coronary heart diseases among Korean males. METHODS: A nested case control study was conducted among a Korea Medical Insurance Cooperation(KMIC) cohort composed of 108,802 males. The cases included 246 male patients who were admitted to hospital due to coronary heart diseases from 1993 to 1997 (I20-25 by ICD) and whose diagnosis was confirmed by the protocol by WHO MONICA Project(1994). The control group was composed of 483 patients selected by frequency matching considering age and resident area from an inpatient care group without coronary heart disease during the same period. For study cases and the controls, the results of a health check-up in 1990 and a questionnaire on life style in 1992 were received through the KMIC. Some additional information was collected by telephone interviews during October 1999. RESULTS: Multiple logistic regression analysis showed that the odds ratio(OR) of coronary heart diseases among past smokers and current smokers as compared to non-smokers were 1.94(95% CI : 1.14-3.31) and 2.20(95% CI : 1.35-3.59), respectively. The OR among persons who drank 4 cups or more of caffeinated beverages such as coffee or tea daily as compared to persons who drank one cup for 2-3 days was 2.56(95% CI : 1.07-6.12). The OR among persons with high normal BP and stage 3 hypertension against normotension were 2.51(95% CI : 1.44-4.37) and 5.08(95% CI : 2.38-10.84). The OR among persons whose blood cholesterol were 240 mg/dL or more against lower than 200mg/dL was 2.24(95% CI : 1.43-3.49). CONCLUSION: Smoking, drinking of excessive caffeinated beverages, hypertension and high blood cholesterol were proven to be significant risk factors for coronary heart diseases among Korean males.; Summary

Risk Factors for Cerebrovascular Disorders in Koreans.: Jong Ku Park, Ki Soon Kim, Chun Bae Kim, Tae Yong Lee, Duk Hee Lee, Kwang Wook Koh, Kang Sook Lee, Sun Ha Jee, Il Suh, So Yeon Ryu, Kee Ho Park; Korean J Prev Med. 2001;34(2):157-165.

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Abstract PDF: OBJECTIVES
To identify the risk factors of cerebrovascular disorders(CVD) in Koreans using a nested case-control study. METHODS: The cohort consisted of beneficiaries who had taken health examinations of the Korea Medical Insurance Corporation (KMIC cohort: 115,600 persons) in 1990 and 1992 consecutively. Four hundred and twenty five (425) cases were selected following the validation of diagnosis among 2,026 reported CVD (I60-I68) inpatients during the year from 1993 to 1997. Controls were matched (1:1) with age and gender of the cases among inpatients without CVD during the same period. The source of data in this study were the files of the 1990 health examinations and the 1992 health questionnaires, as well as an additional telephone survey undertaken from March to November 1999. RESULTS: In a bivariate analysis and multiple logistic regression analysis, risk factors for total CVD were hyperglycemia and hypertension. Unrespectively, the odds ratio of ex-smoker was significantly lower than that of those who had never smoked. The risk factors for ischemic CVD also were hyperglycemia and hypertension. However, only blood pressure was found to be a risk factor for hemorrhagic CVD. Hypercholesterolemia was not a risk factor for total CVD, ischemic CVD, and hemorrhagic CVD. CONCLUSION: We concluded that the most important risk factor for CVD (including subtype) in Koreans was hypertension.; Summary

Trend of the Changes in the Level of Blood Lead, Urinary Arsenic and Urinary Cadmium of Children in Ulsan: 3-year Follow-up Study.: Choong Ryeol Lee, Cheol In Yoo, Ji Ho Lee, Hun Lee, Yangho Kim; Korean J Prev Med. 2001;34(2):166-174.

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Abstract PDF: OBJECTIVES
To obtain basic data on blood lead level and urinary level of arsenic and cadmium of children living near a petrochemical estate and a suburban area in Ulsan, Korea and to observe the trend of the changes in the level of these metals in these children. METHODS: The study subjects comprised 626 children living near a petrochemical estate and 299 children living in a suburban area of Ulsan. We analyzed the level of lead, arsenic and cadmium using atomic absorption spectrometer. RESULTS: The mean levels of blood lead in children living near the petrochemical estate were 5.25 microgram/dl, 5.24 microgram/dl, and 7.24 microgram/dl in the years 1997, 1999, and 2000, respectively, whereas those of children living in the suburban area were 3.81 microgram/dl, 4.75 microgram/dl, and 7.19 microgram/dl respectively. The mean levels of urinary arsenic in children living near the petrochemical estate were 4.57 microgram/g creatinine, 4.78 microgram/g creatinine, and 6.02 microgram /g creatinine in the year 1997, 1999, and 2000 respectively, whereas those of children living in suburban area were 2.35 microgram/g creatinine, 4.75 microgram/g creatinine, and 7.07 microgram/g creatinine, respectively. The mean levels of urinary cadmium in children living near the petrochemical estate were 1.15 microgram/g creatinine, 1.05 microgram/g creatinine, and 1.71 microgram/g creatinine in the year 1997, 1999, and 2000, respectively, whereas those of the children living in the suburban area were 0.74 microgram/g creatinine, 1.29 microgram/g creatinine, and 1.48 microgram/g creatinine, respectively. There were increasing trends in the level of blood lead, urinary arsenic and cadmium of children in Ulsan, and the differences in the level of these metals were disappearing between the children living in other areas year by year. CONCLUSIONS: These results suggest that the amount of exposure to lead, arsenic, and cadmium is increasing from year to year, and there is a need for periodic biological and atmospheric monitoring of these metals in Ulsan.; Summary

Time Series Observations of Outcome Variables and the Factors Associated with the Improvement in the Patient Outcomes of Cataract Surgery.: Han Joong Kim, Eun Cheol Park, Yoon Jung Choi, Hyung Gon Kang; Korean J Prev Med. 2001;34(2):175-181.

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Abstract PDF: OBJECTIVES
To compare the multiple outcomes of patients with cataract surgery at perioperative time, 3-4 months and 12 months after surgery and to assess patient outcomes associated with visual improvement(visual acuity of operated eye, visual function-14(VF-14), symptom score). METHODS: For this assessment, a prospective study was conducted with 389 patients who had undergone cataract surgery for either one eye or both eyes. The surgery was performed by 20 ophthalmologists who were practicing at university hospitals and general hospitals. Patients were interviewed and clinical data were obtained. Doctors were questioned with self-reported questionnaire forms. Medical records were examined in order to measure variables related to the surgical process such as surgical methods and ocular comorbidity. The survey was conducted at 4 stages : preoperative time(389 cases), perioperative time(344 cases, 88.4%), postoperative 3-4 months (343 cases, 88.2%), and postoperative 12 months (281 cases, 72.2%). After excluding cases with incomplete data, 198 cases were enrolled in the study. Patient outcomes was measured for any improvement in the functional outcomes(visual acuity of operated eye, visual function, symptom score) at postoperative 3-4 months. RESULTS: The visual acuity(operated, weighted average), symptom score, VF-14 score, satisfaction with vision, and subjective health status were shown to be improved at the perioperative time, postoperative 3-4 months and 12 months. An improvement in the Snellen visual acuity score was observed in 190 patients(96.0%), whereas improvements of the VF-14 score and cataract symptom score were observed in 151 patients(76.3%) and 179 patients(90.4%), respectively. All three outcome measures demonstrated improvement in 137 patients(69.2%). The improvement of the three functional outcomes at 3-4 months after receiving surgery was associated with a lower level of visual function and a higher level of cataract symptom score at perioperative time, as well as a greater experience level of the surgeon. CONCLUSIONS: In this study, the estimates of the proportion of patients benefiting from cataract surgery varied with the outcome measure of benefit. Preoperative VF-14 score, a measure of functional impairment related to vision, and symptom score may be better measures of the benefit derived from cataract surgery than the change in visual acuity.; Summary

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