OBJECTIVES: To propose a feasible, valid and appropriate study designs and epidemiologic methods for evaluating the adverse health effects of Agent Orange-chemical defoliants used in Vietnam- in Korea. METHODS: A literature study was performed on Agent Orange, herbicides, pesticides and dioxins. The study subjects, study design, exposure assessment and health outcomes assessment were examined in each study. The potential data sources for the study subjects, study design, exposure assessment and health outcomes assessment in Korea were investigated. RESULTS AND CONCLUSION: In earlier Korean studies, research subjects for studying the effects of Agent Orange were identified from the patients or persons who claimed to have Agent Orange-related diseases due to the difficulties in identifying the entire population of Vietnam veterans in Korea. In this study, an attempt was made to identify the total number of Vietnam veterans in Korea. As a result, the addresses of 20,000 Vietnam veterans were obtained. It is proposed that a retrospective cohort design on a sample of the total number of Vietnam veterans is a feasible and appropriate study design. Self report questionnaires and military records were proposed to assess the exposure level. It is believed that measuring the plasma or tissue TCDD should be used only for a validation study assessing the level of exposure. For the health outcomes assessment, it is possible to obtain the mortality, cancer frequency, physical examination, screening and medical insurance record data.
Citrus sinensis* ; Cohort Studies ; Data Collection ; Defoliants, Chemical ; Dioxins ; Epidemiologic Methods ; Herbicides ; Humans ; Insurance ; Korea ; Mass Screening ; Military Personnel ; Mortality ; Outcome Assessment (Health Care) ; Pesticides ; Physical Examination ; Plasma ; Questionnaires ; Research Subjects ; Retrospective Studies ; Self Report ; Tetrachlorodibenzodioxin ; Veterans* ; Vietnam*

OBJECTIVES: The aim of this study was to examine the levels of serum 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and evaluate their association with age, body mass index, smoking, military record-based variables, and estimated exposure to Agent Orange in Korean Vietnam veterans. METHODS: Serum levels of TCDD were analyzed in 102 Vietnam veterans. Information on age, body mass index, and smoking status were obtained from a self-reported questionnaire. The perceived exposure was assessed by a 6-item questionnaire. Two proximity-based exposures were constructed by division/brigade level and battalion/company level unit information using the Stellman exposure opportunity index model. RESULTS: The mean and median of serum TCDD levels was 1.2 parts per trillion (ppt) and 0.9 ppt, respectively. Only 2 Vietnam veterans had elevated levels of TCDD (>10 ppt). The levels of TCDD did not tend to increase with the likelihood of exposure to Agent Orange, as estimated from either proximity-based exposure or perceived self-reported exposure. The serum TCDD levels were not significantly different according to military unit, year of first deployment, duration of deployment, military rank, age, body mass index, and smoking status. CONCLUSIONS: The average serum TCDD levels in the Korean Vietnam veterans were lower than those reported for other occupationally or environmentally exposed groups and US Vietnam veterans, and their use as an objective marker of Agent Orange exposure may have some limitations. The unit of deployment, duration of deployment, year of first deployment, military rank, perceived self-reported exposure, and proximity-based exposure to Agent Orange were not associated with TCDD levels in Korean Vietnam veterans. Age, body mass index and smoking also were not associated with TCDD levels.
2,4,5-Trichlorophenoxyacetic Acid/*poisoning ; 2,4-Dichlorophenoxyacetic Acid/*poisoning ; Adult ; Age Factors ; *Body Mass Index ; Defoliants, Chemical/*poisoning ; Humans ; Male ; Middle Aged ; Questionnaires ; Regression Analysis ; Republic of Korea/epidemiology ; Self Report ; Smoking/*blood ; Tetrachlorodibenzodioxin/*blood/poisoning ; Time Factors ; Veterans/*statistics & numerical data ; Vietnam Conflict ; Young Adult

OBJECTIVES: The aim of this study was to evaluate the association between Agent Orange exposure and self-reported diseases in Korean Vietnam veterans. METHODS: A postal survey of 114 562 Vietnam veterans was conducted. The perceived exposure to Agent Orange was assessed by a 6-item questionnaire. Two proximity-based Agent Orange exposure indices were constructed using division/brigade-level and battalion/company-level unit information. Adjusted odds ratios (ORs) for age and other confounders were calculated using a logistic regression model. RESULTS: The prevalence of all self-reported diseases showed monotonically increasing trends as the levels of perceived self-reported exposure increased. The ORs for colon cancer (OR, 1.13), leukemia (OR, 1.56), hypertension (OR, 1.03), peripheral vasculopathy (OR, 1.07), enterocolitis (OR, 1.07), peripheral neuropathy (OR, 1.07), multiple nerve palsy (OR, 1.14), multiple sclerosis (OR, 1.24), skin diseases (OR, 1.05), psychotic diseases (OR, 1.07) and lipidemia (OR, 1.05) were significantly elevated for the high exposure group in the division/brigade-level proximity-based exposure analysis, compared to the low exposure group. The ORs for cerebral infarction (OR, 1.08), chronic bronchitis (OR, 1.05), multiple nerve palsy (OR, 1.07), multiple sclerosis (OR, 1.16), skin diseases (OR, 1.05), and lipidemia (OR, 1.05) were significantly elevated for the high exposure group in the battalion/company-level analysis. CONCLUSIONS: Korean Vietnam veterans with high exposure to Agent Orange experienced a higher prevalence of several self-reported chronic diseases compared to those with low exposure by proximity-based exposure assessment. The strong positive associations between perceived self-reported exposure and all self-reported diseases should be evaluated with discretion because the likelihood of reporting diseases was directly related to the perceived intensity of Agent Orange exposure.
2,4,5-Trichlorophenoxyacetic Acid/*poisoning ; 2,4-Dichlorophenoxyacetic Acid/*poisoning ; Cardiovascular Diseases/epidemiology/etiology ; Defoliants, Chemical/*poisoning ; Endocrine System Diseases/epidemiology/etiology ; Gastrointestinal Diseases/epidemiology/etiology ; Humans ; Logistic Models ; Male ; Middle Aged ; Neoplasms/epidemiology/etiology ; Neuromuscular Diseases/epidemiology/etiology ; Odds Ratio ; Prevalence ; Republic of Korea/epidemiology ; Respiratory Tract Diseases/epidemiology/etiology ; *Self Report ; Tetrachlorodibenzodioxin/*poisoning ; *Veterans ; Vietnam Conflict