Agent Orange Exposure and Prevalence of Self-reported Diseases in Korean Vietnam Veterans

Abstract

ObjectivesThe aim of this study was to evaluate the association between Agent Orange exposure and self-reported diseases in Korean Vietnam veterans.MethodsA 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.ResultsThe 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.ConclusionsKorean 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.

A critical review of the epidemiology of Agent Orange or 2,3,7,8-tetrachlorodibenzo-p-dioxin and lymphoid malignancies

“…Both the studies are also undermined by untrustworthy exposure data [126,127]. Among 102 South Korean veterans of the Vietnam War in 2007, serum TCDD levels were not significantly correlated with self-reported perceived exposure to Agent Orange (r 2 ¼ 0.129), division-or brigade-level proximity-based exposure (r 2 ¼ 0.073), or battalion-or company-level proximity-based exposure (r 2 ¼ 0.159) [129].…”

“…In the cross-sectional analysis [126], self-perceived Agent Orange exposure was significantly associated with the prevalence of all three of the lymphoid malignancies, including NHL (OR for high vs. no exposure ¼ 2. 93 Table 2).…”

“…The most recent group in which associations have been estimated between Agent Orange exposure and risk of NHL, HL, and MM is the cohort of South Korean veterans of the Vietnam War [126,127]. Studies in this group include a cross-sectional analysis of self-reported cancer prevalence based on a postal survey completed by 114,562 veterans [126] and a retrospective cohort study of cancer incidence among 180,251 veterans linked to the national cancer incidence database [127].…”

“…Although statistically strengthened by large numbers [126], the cross-sectional analysis is limited by unreliable outcome data. Self-reported cancer diagnoses were not validated based on medical records, and the fact that the frequency of self-reported MM was roughly 10 times that of self-reported NHL in this study suggests that outcome data were highly misclassified, given that the true incidence and prevalence rates of NHL in South Korean males aged 50 to 69 years are approximately triple those for MM [25].…”

“…Studies in this group include a cross-sectional analysis of self-reported cancer prevalence based on a postal survey completed by 114,562 veterans [126] and a retrospective cohort study of cancer incidence among 180,251 veterans linked to the national cancer incidence database [127]. Potential exposure to Agent Orange was evaluated based on the proximity of the respondent's division or brigade (and, in the cross-sectional study, based on the proximity of the respondent's self-reported battalion or company) to sprayed areas, using the Agent Orange Exposure Opportunity Index model E4 developed by Stellman et al [128].…”