Ecological effects of the war in Vietnam. Effects of defoliation, bombing, and other military activities on the ecology of Vietnam are described.
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AIMS: To seek clues in the Vietnam study of 30 years ago that might shed light on which previous users of heroin are at special risk of relapsing and, among relapsers, to identify those likely to begin or return to injecting heroin. DESIGN: To analyse information in military records and in two interviews given in the first 3 years after return from Vietnam to find predictors of post-Vietnam injection by soldiers who had used heroin while in Vietnam in 1970-71. PARTICIPANTS: A total of 374 Vietnam veterans who had used heroin while in Vietnam and had been interviewed twice since their return from Vietnam. MEASUREMENTS: Post-Vietnam heroin injection was determined in either of two post-Vietnam interviews. Possible predictors came from interviews and military records and describe pre-Service and in-Vietnam status and behavior. Included are region of residence, race, antisocial behavior, type and level of drug use and association with illicit drug users. Possible post-Vietnam correlates of heroin injection were no job or school enrollment, alcohol problems, depression, absent or transient marriage, association with illicit drug users and other Vietnam veterans. FINDINGS: Only a minority of those who used heroin in Vietnam had ever injected it there. Most smoked or snorted it. After their return, most of the men who had used heroin in Vietnam used it very occasionally or not at all. Among those who did use heroin more than five times after their return, most had tried injecting it. Significant predictors of post-Vietnam injection included living on the east or west coast, deviant behavior both before and in Vietnam, opiate use before Vietnam, serious involvement with heroin in Vietnam, use of non-opiate drugs before and in Vietnam, and associating with drug users before Service. The variables that increased significantly the probability of injection among men who relapsed to heroin use after return to the United States were living on the east or west coast and having a history of using non-opiate illegal drugs before they entered Service. Blacks who returned to heroin use after return were less likely to inject than were non-blacks. CONCLUSIONS: These results suggest that a high-risk group for intervention to prevent future injection would consist of people with a history of past heroin use who are currently either in remission or using without injection and who reside on either coast, have a history of antisocial behavior and have used a variety of illicit drugs other than heroin.
BACKGROUND: During the 1980s, the postservice mortality component of the Vietnam Experience Study was conducted to examine the health effects of the Vietnam experience. This study was limited by the relatively short follow-up and the young age of the veterans. Thus, a follow-up mortality investigation on this cohort was undertaken to further assess the impact of the Vietnam experience on chronic conditions. METHODS: Vital status and underlying cause-of-death data on the Vietnam Experience Study cohort (18 313 male US Army veterans) were retrospectively ascertained from the end of the original study through 2000. Cox proportional hazards regression was used to calculate crude and adjusted rate ratios (RRs) for all-cause and cause-specific mortality, comparing Vietnam and non-Vietnam veterans. RESULTS: All-cause mortality was 7% higher in Vietnam vs non-Vietnam veterans during 30-year follow-up (95% confidence interval [CI], 0.97-1.18). The excess mortality among Vietnam veterans was isolated to the first 5 years after discharge from active duty and resulted from an increase in external causes of death (RR, 1.62; 95% CI, 1.16-2.26). Cause-specific analyses revealed no difference in disease-related mortality. Vietnam veterans, however, experienced excess unintentional poisoning (RR, 2.26; 95% CI, 1.12-4.57) and drug-related (RR, 1.70; 95% CI, 1.01-2.86) deaths throughout follow-up. CONCLUSIONS: Vietnam veterans continued to experience higher mortality than non-Vietnam veterans from unintentional poisonings and drug-related causes. Death rates from disease-related chronic conditions, including cancers and circulatory system diseases, did not differ between Vietnam veterans and their peers, despite the increasing age of the cohort (mean age, 53 years) and the longer follow-up (average, 30 years).
BACKGROUND: Potential exposure of ground troops in Vietnam to Agent Orange and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) remains controversial despite the passage of 30 years since the Vietnam War. Because of uncertainty over the serum dioxin levels in ground troops at the end of their service in Vietnam, attempts have been made to develop a methodology for characterizing exposure of ground troops in Vietnam to Agent Orange and other herbicides based upon historical reconstruction from military records. Historical information is often useful in evaluating and modeling exposure, but such information should be reasonably accurate, complete, and reliable. METHODS: This paper reviews the procedures and supporting historical information related to the spraying of herbicides in Vietnam. The historical information is classified into two categories: procedural information and operational information. Procedural information covered the process and procedures followed in spraying herbicides from US Air Force fixed wing aircraft (Operation RANCH HAND) in Vietnam, and included approval procedures for spray missions, the criteria required to conduct a mission, the control exercised by the Forward Air Controller and the Tactical Air Control Center and the characteristics of the equipment used to apply the herbicides. Operational information includes data from the RANCH HAND Daily Air Activities Reports, which included geographic locations of specific spray missions, the amount of herbicide sprayed by a specific mission, reports of battle damage to spray aircraft, reports of fighter aircraft support for aerial spray missions, and any comments, such as reasons for canceling a mission. RESULTS: Historical information demonstrates that herbicide spray missions were carefully planned and that spraying only occurred when friendly forces were not located in the target area. RANCH HAND spray missions were either not approved or cancelled if approved when there were friendly forces in the area designated for spraying. Stringent criteria had to be met before spray missions could be approved. The operational information shows that spray missions for both defoliation and crop destruction were conducted in an extremely hostile environment. Heavy 'fighter suppression' with antipersonnel ordnance was used to minimize the impact of hostile ground fire on RANCH HAND aircraft. Procedures were in place that prohibited movement of troops into sprayed areas immediately after a mission due to the possible presence of unexploded ordnance delivered by fighter aircraft supporting RANCH HAND missions. The optimal nature of the spray equipment and application procedures minimized the possibility of significant spray drift. Conclusions. Few friendly troops were sprayed by fixed wing aircraft during Operation RANCH HAND, which delivered 95% of all defoliants used in Vietnam. Similarly, few troops were sprayed during helicopter or surface-based spray operations, which constituted the remaining 5% of defoliants. Detailed policies and procedures for approval and execution of spray missions ensured that friendly forces were not located in the areas targeted for spraying. Fighter aircraft assigned to accompany each spray mission frequently suppressed much of the hostile fire with bombs and other ordnance. Confirmed clearance of the target area was necessary to avoid friendly casualties. Historical records establish that these policies and procedures were strictly followed. Exposure of troops whether from direct spraying or movement through areas recently sprayed was very unlikely. The wartime military records of troop positions and herbicide operations are valuable for some purposes, but have specific limitations in exposure reconstruction. The completeness and accuracy of the geographic data (maps used by RANCH HAND and military ground units) were dependent upon the inherent precision of the map, the accuracy with which it depicted surface features, and the completeness and accuracy of the information on which it is based. Navigation by the crew using visual orientation and reference to the map was the only means that aircrew on spray missions had for establishing their locations. A Forward Air Controller independent of Operation RANCH HAND was present at the location of each spray target immediately before and during spraying operations to verify the target location and ensure that friendly forces were clear of the target area. Anecdotal reports of direct spraying of troops in Vietnam likely reflect the RANCH HAND missions spraying insecticide for mosquito control at regular intervals from March 1967 through February 1972. Outlook. The distribution and levels of serum dioxin in RANCH HAND veterans and the US Army Chemical Corps Vietnam veterans (the unit responsible for helicopter and ground-based spray operations) are distinguishable from typical levels in the population decades after the Vietnam conflict. An exposure model similar to that proposed in the 2003 report of the Institute of Medicine's Committee on 'Characterizing Exposure of Veterans to Agent Orange and Other Herbicides Used in Vietnam' was tested in 1988 by the Centers for Disease Control and Prevention and found to be a poor predictor of absorbed dose of TCDD. Military records during the Vietnam War lack the precision to determine that troops were directly sprayed with herbicides during Operation RANCH HAND, especially given the procedures in place to ensure clearance of friendly forces from the target area and the lack of elevated serum levels of TCDD in ground troops judged to have operated in heavily sprayed areas.
A retrospective cohort mortality study was conducted to examine health effects of US military service in Vietnam on women veterans who served there between July 4, 1965 and March 28, 1973. About 4,600 women Vietnam veterans and 5,300 women veterans who had never served in Vietnam were identified from military records and followed for vital status on December 31, 1987. Mortality rates for all causes of death combined and for all cancers among Vietnam veterans were similar to those among non-Vietnam veterans (relative risk (RR) = 0.93). There was a slight excess of mortality from external causes among women Vietnam veterans compared with non-Vietnam veterans (RR = 1.33), primarily due to an excess of motor vehicle accidents (RR = 3.19). Suicide rates were nearly the same in both cohorts (RR = 0.96). Vietnam veterans had twofold increases in mortality from cancers of the pancreas and uterine corpus compared with non-Vietnam veterans. Women Vietnam veterans and non-Vietnam veterans had lower-than-expected mortality from all causes of death combined (standardized mortality ratio (SMR) = 0.82 and 0.88, respectively), based on rates for US women, due to significant deficits of deaths from circulatory diseases. Compared with rates for US women, mortality from cancers of the pancreas (five deaths, SMR = 3.27) and uterine corpus (four deaths, SMR = 4.05) was significantly elevated among Vietnam veteran nurses.
As part of an epidemiologic study of the health status of a randomly selected group of Vietnam veterans, we measured the semen characteristics of 324 Vietnam veterans and compared them with a similar group of 247 veterans who did not serve in Vietnam. The participation rate was 81% in both groups. Measurements of sperm concentration, movement characteristics, and head dimensions were performed, using the Cellsoft computer-assisted semen analysis system. We found that Vietnam veterans had significantly (p less than 0.05) lowered mean sperm concentrations (64.8 x 10(6) sperm/mL for Vietnam veterans vs 79.8 x 10(6) sperm/mL for non-Vietnam veterans), and Vietnam veterans were twice as likely to have sperm concentrations less than or equal to 20 million/mL (odds ratio = 2.7, 95% confidence interval = 1.3-5.7). Vietnam veterans also had a significantly lowered mean proportion of morphologically normal sperm heads (57.9% vs 60.8%), with significantly longer mean major axis length and head circumference. The proportion of motile cells, velocity, linearity, amplitude of lateral head displacement, and beat frequency were not different between the two groups. Despite differences in sperm characteristics, Vietnam and non-Vietnam veterans reported fathering similar numbers of children.
The long-term health consequences of exposure to phenoxyherbicides used in Vietnam has been a great concern to the veterans. In addition to the Air Force Ranch Hand personnel, Army Chemical Corps personnel who served in Vietnam are thought to have had some of the highest herbicide exposures. The Department of Veterans Affairs commenced a study of veterans who served in Vietnam as members of the Army Chemical Corps and a comparison cohort of Army Chemical Corps personnel who served elsewhere. A total of 2872 Vietnam veterans and 2737 non-Vietnam veterans who served in the Army Chemical Corps were identified for inclusion in a telephone health interview survey with a random 20% sample of veterans receiving serum dioxin and other congeners assessments. In a feasibility study which included 284 Vietnam veterans and 281 non-Vietnam veterans, 100 serum assessments were conducted of which 95 were included in the analysis. Vietnam veterans with a history of spraying herbicides were found to have a statistically significant elevation in their current serum 2,3,7,8-TCDD concentrations compared to non-Vietnam veterans without a spray history (P = 0.05). Other 2,3,7,8-substituted dioxins levels were comparable to the levels found in the non-Vietnam veterans. This feasibility study demonstrated that serum dioxin concentrations from a sample of the study participants can be used to identify exposure variables in the health survey that can serve as a surrogate measure of phenoxyherbicide exposure.