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PubMed1994

Risk of testicular cancer associated with surrogate measures of Agent Orange exposure among Vietnam veterans on the Agent Orange Registry.

A case-control analysis was undertaken to examine the association between various surrogate measures of Agent Orange exposure and testicular cancer among Vietnam veterans. Study subjects were selected from the Department of Veterans Affairs Agent Orange Registry. The case patients consisted of 97 veterans with a diagnosis of testicular cancer, and 311 veterans without any clinical diagnosis served as a comparison group. The surrogate measures were branch of service, type of duty, corps area, and location of the individual's unit in relation to recorded Agent Orange spray tracts. Only Navy veterans had a statistically significant increased risk of testicular cancer (odds ratio (OR) = 2.60; 95% confidence interval (CI), 1.08 to 6.24). Risk of testicular cancer was not significantly increased for ground troops (OR = 0.46; 95% CI, 0.25 to 0.86), for combat duty (OR = 0.91; 95% CI, 0.52 to 1.58), for service in the III Corps area (OR = 1.10; 95% CI, 0.66 to 1.84), and for being close to spray tracts within 90 days/8 km (OR = 0.99; 95% CI, 0.54 to 1.84) or 3 days/2 km (OR = 1.39; 95% CI, 0.50 to 3.80). The study results are not consistent with the hypothesis that Agent Orange may be a risk factor for testicular cancer among Vietnam veterans.

2,4,5-Trichlorophenoxyacetic Acid↗

PubMed2001

Prostate cancer detection in veterans with a history of Agent Orange exposure.

PURPOSE: Agent Orange, a chemical that was widely used in the Vietnam War as a defoliant, is widely accepted as a health hazard but its potential causative role in prostate cancer has been controversial. We evaluated the rate of prostate cancer in veterans referred for prostate biopsy who reported a history of Agent Orange exposure compared to the rate in veterans who denied such exposure. MATERIALS AND METHODS: A total of 400 consecutive veterans referred for prostate needle biopsy in a 30-month period completed a survey regarding Agent Orange exposure. Of these 400 patients 32 (8%) reported previous exposure to Agent Orange. From the remaining 368 patients who denied Agent Orange exposure 3 consecutive age matched controls were selected per each patient reporting exposure for a total of 96 age matched controls. Prostate specific antigen, prostate cancer, cancer grade and length of cancer in the biopsy cores were compared in Agent Orange exposed patients and unexposed controls. To determine whether the patient population referred for biopsy was skewed by proportionally more exposed and referred than unexposed patients those referred for biopsy were compared to the overall adult male veteran population followed at the outpatient clinics at our facility. RESULTS: Of the 32 Agent Orange exposed patients 13 (41%) had prostate cancer, while 33 of the 96 controls (34.4%) had cancer. There was no correlation of Agent Orange exposure with cancer (r = 0.06). There was also no statistically significant difference in the 2 groups in regard to PSA (p = 0.90), cancer (p = 0.15), proportion of well differentiated cancers (p = 0.41) or length of cancer in the biopsy cores (p = 0.34). Compared with the total adult male veteran population followed on an outpatient basis at our facility an average of 1.07% of those with a history of Agent Orange exposure were referred for prostate biopsy yearly versus 1.33% of unexposed patients. CONCLUSIONS: Agent Orange may have a role in the causation of some types of cancer but we identified no significant relationship of prostate cancer with Agent Orange exposure in patients referred for prostate biopsy.

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PubMed1988

Collective judicial management of mass toxic tort controversies: lessons and issues from the Agent Orange litigation.

Viewing the Agent Orange litigation as a case study, this article explores the feasibility and desirability of strengthening the powers of the courts to manage toxic tort controversies en masse. The Agent Orange lawsuit, brought on behalf of potentially millions of Vietnam War veterans and family members, charged that herbicides used for military purposes during the war caused a wide range of health problems. This article first reviews the current national debate over how mass toxic tort controversies should be handled, including key legislative reform options, and describes how attention is increasingly focused on ways that the court system might better cope with mass toxic torts. The principal events of the Agent Orange litigation are then summarized, by which the litigation was consolidated into a massive class action, the class action was settled, and a streamlined plan for distributing the settlement fund was adopted. The article evaluates the outcome of the litigation, and discusses whether the solution there can and should be broadly applied to other mass toxic tort cases. This question depends, in part, on a series of complex legal and practical issues, but the author suggests that the question will also depend on what institutional role we expect the judiciary to play within society.

2,4,5-Trichlorophenoxyacetic Acid↗

PubMed2005

Natural selection for 2,4,5-trichlorophenoxyacetic acid mineralizing bacteria in agent orange contaminated soil.

Agent Orange contaminated soils were utilized in direct enrichment culture studies to isolate 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) and 2,4-dichlorophenoxyacetic acid (2,4-D) mineralizing bacteria. Two bacterial cultures able to grow at the expense of 2,4,5-T and/or 2,4-D were isolated. The 2,4,5-T degrading culture was a mixed culture containing two bacteria, Burkholderia species strain JR7B2 and Burkholderia species strain JR7B3. JR7B3 was able to metabolize 2,4,5-T as the sole source of carbon and energy, and demonstrated the ability to affect metabolism of 2,4-D to a lesser degree. Strain JR7B3 was able to mineralize 2,4,5-T in pure culture and utilized 2,4,5-T in the presence of 0.01% yeast extract. Subsequent characterization of the 2,4-D degrading culture showed that one bacterium, Burkholderia species strain JRB1, was able to utilize 2,4-D as a sole carbon and energy source in pure culture. Polymerase chain reaction (PCR) experiments utilizing known genetic sequences from other 2,4-D and 2,4,5-T degrading bacteria demonstrated that these organisms contain gene sequences similar to tfdA, B, C, E, and R (Strain JRB1) and the tftA, C, and E genes (Strain JR7B3). Expression analysis confirmed that tftA, C, and E and tfdA, B, and C were transcribed during 2,4,5-T and 2,4-D dependent growth, respectively. The results indicate a strong selective pressure for 2,4,5-T utilizing strains under field condition.

2,4,5-Trichlorophenoxyacetic Acid↗

PubMed1984

Does Agent Orange cause birth defects?

Large quantities of the defoliant, Agent Orange, were sprayed in Vietnam during the war. Agent Orange was composed of two herbicides: 2,4-D and 2,4,5-T, the latter contaminated by small amounts of a highly toxic dioxin (TCDD). The constituents of Agent Orange are capable of producing gene mutations and chromosomal aberrations, at least in some experimental circumstances. TCDD and 2,4,5-T are teratogenic in mice and perhaps in other mammals, but the teratogenicity of these chemicals has not been convincingly demonstrated in humans. There is currently no scientific evidence which indicates that men who were previously exposed to Agent Orange are at increased risk of having children with birth defects, but available data are inadequate to assess this possibility critically.

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PubMed1985

Evaluation of chromosomal damage in males exposed to agent orange and their families.

Agent Orange (AO), a phenoxyherbicide, and dioxin, an impurity found in AO, are considered clastogens, mutagens, and teratogens in plants and animals. AO has come under suspicion in humans following claims that it causes chromosome damage and birth defects in offspring of exposed individuals. No well-designed epidemiological studies are available to support this conclusion. Of ten exposed individuals studied for chromosome breaks and sister chromatid exchange frequencies, eight were ascertained because they had children with congenital defects. No consistent pattern of anomalies was observed. Five children had neurologic deficit, one child had a central nervous system anomaly, and one child was affected with glaucoma. Although all individuals studied had normal karyotypes, a statistically significant increase in chromosome breakage was observed in exposed males compared to their unexposed wives and children; sister chromatid exchange frequency was not increased.

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PubMed2001

Recent dioxin contamination from Agent Orange in residents of a southern Vietnam city.

Marked elevation of dioxin associated with the herbicide Agent Orange was recently found in 19 of 20 blood samples from persons living in Bien Hoa, a large city in southern Vietnam. This city is located near an air base that was used for Agent Orange spray missions between 1962 and 1970. A spill of Agent Orange occurred at this air base more than 30 years before blood samples were collected in 1999. Samples were collected, frozen, and sent to a World Health Organization--certified dioxin laboratory for congener-specific analysis as part of a Vietnam Red Cross project. Previous analyses of more than 2200 pooled blood samples collected in the 1990s identified Bien Hoa as one of several southern Vietnam areas with persons having elevated blood dioxin levels from exposure to Agent Orange. In sharp contrast to this study, our previous research showed decreasing tissue dioxin levels over time since 1970. Only the dioxin that contaminated Agent Orange, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), was elevated in the blood of 19 of 20 persons sampled from Bien Hoa. A comparison, pooled sample from 100 residents of Hanoi, where Agent Orange was not used, measured blood TCDD levels of 2 parts per trillion (ppt). TCDD levels of up to 271 ppt, a 135-fold increase, were found in Bien Hoa residents. TCDD contamination was also found in some nearby soil and sediment samples. Persons new to this region and children born after Agent Orange spraying ended also had elevated TCDD levels. This TCDD uptake was recent and occurred decades after spraying ended. We hypothesize that a major route of current and past exposures is from the movement of dioxin from soil into river sediment, then into fish, and from fish consumption into people.

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PubMed2004

Association between Agent Orange and prostate cancer: a pilot case-control study.

OBJECTIVES: To estimate in a pilot study the risk of being diagnosed with prostate cancer after exposure to Agent Orange in a clinical population of military veterans. Prostate cancer is the most common cancer diagnosed in American men and the second leading cause of cancer deaths. An association between Agent Orange and prostate cancer has been suggested by epidemiologic studies. METHODS: A case-control study was conducted at the Department of Veterans Affairs Medical Center in Ann Arbor, Michigan. Cases of pathologically diagnosed prostate cancer were identified and age matched in a 1:3 ratio with controls. Exposure to Agent Orange was assessed by reviewing the administrative portion of the computerized medical records. A subanalysis of the cases was conducted to examine the clinical features of prostate cancer in men reporting exposure to Agent Orange versus those who did not report exposure. RESULTS: A total of 47 military veterans with prostate cancer and 142 control men without prostate cancer were selected. After adjusting for age and race, men with prostate cancer were approximately two times more likely to report previous exposure to Agent Orange (odds ratio 2.06; 95% confidence interval 0.81 to 5.23). CONCLUSIONS: The results from this pilot study suggest exposure to Agent Orange is associated with an increased risk of prostate cancer. Additional study in larger populations is necessary to confirm and to quantify this association more accurately.

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PubMed2003

Impact of Agent Orange exposure among Korean Vietnam veterans.

In order to determine whether Agent Orange exposure was associated with increased frequency of medical problems, we conducted a cross-sectional epidemiologic study of Korean veterans during 1995-1996. 1,224 Vietnam and 154 non-Vietnam veterans were included in the study. Exposure to Agent Orange was assessed by structured in-depth interview on the participants' history of service in Vietnam. Health outcomes were assessed by a standardized comprehensive clinical investigation by a group of clinical specialists. The differences in the prevalence of various medical diagnoses were assessed by Cochran-Mantel-Haenszel chi-square tests comparing the exposure levels of Vietnam veterans, adjusting for age. Multiple logistic regression was performed to estimate the effect of "service in Vietnam" adjusting for age, smoking, alcohol, body mass index, education, and marital status. Vietnam veterans had an increased frequency of eczema (odds ratio [OR] = 6.54), radiculopathy (OR = 3.98), diabetes (OR = 2.69), peripheral neuropathy (OR = 2.39), and hypertension (OR = 2.29), compared to non-Vietnam veterans, adjusting for potential confounders. In addition, higher levels of exposure among Vietnam veterans were associated with increased frequency of ischemic heart disease (p < 0.01), valvular heart disease (p < 0.01), and retinopathy (p < 0.01). We conclude that exposure to Agent Orange is associated with various health impacts in Korean Vietnam veterans.

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PubMed2003

Are Vietnamese food exports contaminated with dioxin from Agent Orange?

In this study the levels of dioxins and dioxinlike compounds, dibenzofurans, and polychlorinated biphenyls (PCBs) were measured in food exported from Vietnam to the United States. In the past, some Vietnamese fish was found to be contaminated with dioxin, 2,3,7,8-TCDD, or TCDD, from Agent Orange. U.S. commercial catfish farmers recently claimed that exported Vietnamese food, especially catfish, was contaminated with dioxin from Agent Orange and was thus a matter of concern to the U.S. Congress. In 2001, twenty-two exported Vietnamese food samples (mostly fish) were purchased in the United States and Laos to evaluate possible contamination with dioxin from Agent Orange. Dioxin, dibenzofuran, and coplanar PCB congeners were measured by high-resolution gas chromatography-high-resolution mass spectrometry by laboratories in Germany and Canada certified for dioxin analysis by the World Health Organization (WHO). In the current study, only low levels of dioxins and dioxinlike compounds were present in all exported Vietnamese food analyzed, despite recent findings of elevated levels of one dioxin, 2,3,7,8-TCDD, from Agent Orange exposure in some Vietnamese individuals, presumably due to food consumption. It appears unlikely that exported Vietnamese food is, in general, contaminated with large amounts of dioxin (TCDD) from Agent Orange or other sources. Further food sampling from areas of heavy Agent Orange spraying in Vietnam is warranted to map out where the source of TCDD contamination of food may be originating.

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PubMed2006

Association between Agent Orange and birth defects: systematic review and meta-analysis.

BACKGROUND: The association between parental exposure to Agent Orange or dioxin and birth defects is controversial, due to inconsistent findings in the literature. The principal aim of this study was to conduct a meta-analysis of relevant epidemiological studies that examined this association and to assess the heterogeneity among studies. METHODS: Relevant studies were identified through a computerized literature search of Medline and Embase from 1966 to 2002; reviewing the reference list of retrieved articles and conference proceedings; and contacting researchers for unpublished studies. A specified protocol was followed to extract data on study details and outcomes. Both fixed-effects and random-effects models were used to synthesize the results of individual studies. The Cochrane Q test and index of heterogeneity (I2) were used to evaluate heterogeneity, and a funnel plot and Egger's test were used to evaluate publication bias. RESULTS: In total, 22 studies including 13 Vietnamese and nine non-Vietnamese studies were identified. The summary relative risk (RR) of birth defects associated with exposure to Agent Orange was 1.95 [95% confidence interval (95% CI) 1.59-2.39], with substantial heterogeneity across studies. Vietnamese studies showed a higher summary RR (RR = 3.00; 95% CI 2.19-4.12) than non-Vietnamese studies (RR = 1.29; 95% CI 1.04-1.59). Sub-group analyses found that the magnitude of association tended to increase with greater degrees of exposure to Agent Orange, rated on intensity and duration of exposure and dioxin concentrations measured in affected populations. CONCLUSION: Parental exposure to Agent Orange appears to be associated with an increased risk of birth defects.

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PubMed2006

Agent Orange, dioxins, and other chemicals of concern in Vietnam: update 2006.

OBJECTIVE: The objective of this study was to find sites in Vietnam where there was human exposure from Agent Orange herbicide sprayed between 1962 and 1971, as determined by congener-specific measurement of dioxins, including 2,3,7,8-tetrachlorodibenzodioxin (TCDD), the dioxin that contaminated Agent Orange, in blood. METHODS: Blood was collected from residents of eight heavily sprayed regions in the south of Vietnam and analyzed for TCDD and in some cases the dioxin-like dibenzofurans and dioxin-like PCBs. RESULTS: Six of the eight newly studied sites did not show substantial or any elevated TCDD in blood. Marked elevation of TCDD in Vietnamese blood was found in one new location with a suggestion of slightly elevated TCDD in a second location. CONCLUSIONS: In newly studied locations in Vietnam, we found some persons with elevation of TCDD consistent with exposure to dioxin from Agent Orange. In our previous studies, we found PCBs, PCDDs, and PCDFs as well as pesticides in human milk, blood, or in food. Health effects from Agent Orange need to be differentiated from effects caused by chemicals other than TCDD from Agent Orange.

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PubMedDate not supplied

Agent Orange: management of patients exposed in Vietnam.

Since the Vietnam War ended in 1975, numerous studies have been conducted to determine if an association exists between Agent Orange exposure and certain disabling conditions specifically cancer. Although a definite causal relationship has not yet been established, sufficient data associate Agent Orange with certain conditions. Because of their advancing age similar to other baby boomers, Vietnam veterans are at a higher risk of developing malignancies. However, their exposure to Agent Orange also may increase their risk for cancer and other associated diseases. This article examines the latest findings of scientific research sponsored by the Department of Veterans Affairs and discusses the importance of well-informed oncology nurses when providing care for patients with cancer exposed to Agent Orange.

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PubMed2004

Environmental fate and bioavailability of Agent Orange and its associated dioxin during the Vietnam War.

BACKGROUND: In 1996, the Committee on the Assessment of Wartime Exposure to Herbicides in Vietnam of the National Academy of Sciences' Institute of Medicine (IOM) issued a report on an exposure model for use in epidemiological studies of Vietnam veterans. This exposure model would consider troop locations based on military records; aerial spray mission data; estimated ground spraying activity; estimated exposure opportunity factors; military indications for herbicide use; and considerations of the composition and environmental fate of herbicides, including changes in the TCDD content of the herbicides over time, the persistence of TCDD and herbicides in the environment, and the degree of likely penetration of the herbicides into the ground. When the final report of the IOM Committee was released in October 2003, several components of the exposure model envisioned by the Committee were not addressed. These components included the environmental fate of the herbicides, including changes in the TCDD content over time, the persistence of TCDD and herbicides in the environment, and the degree of likely penetration of herbicides into the ground. This paper is intended to help investigators understand better the fate and transport of herbicides and TCDD from spray missions, particularly in performing epidemiological studies. METHODS: This paper reviews the published scientific literature related to the environmental fate of Agent Orange and the contaminant, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), and discusses how this affected the potential exposure to TCDD of ground troops in Vietnam. Specifically, the mechanisms of dissipation and degradation as they relate to environmental distribution and bioavailability are addressed. RESULTS: The evaluation of the spray systems used to disseminate herbicides in Vietnam showed that they were capable of highly precise applications both in terms of concentrations sprayed and area treated. Research on tropical forest canopies with leaf area indices (a measure of foliage density) from 2 to 5 indicated that the amount of herbicide and associated TCDD reaching the forest floor would have been between 1 and 6% of the total aerial spray. Studies of the properties of plant surface waxes of the cuticle layer suggested that Agent Orange, including the TCDD, would have dried (i.e., be absorbed into the wax layer of the plant cuticle) upon spraying within minutes and could not be physically dislodged. Studies of Agent Orange and the associated TCDD on both leaf and soil surface have demonstrated that photolysis by sunlight would have rapidly decreased the concentration of TCDD, and this process continued in shade. Studies of 'dislodgeable foliar residues' (DFR, the fraction of a substance that is available for cutaneous uptake from the plant leaves) showed that only 8% of the DFR was present 1 hr after application. This dropped to 1% of the total 24 hrs after application. Studies with human volunteers confirmed that after 2 hrs of saturated contact with bare skin, only 0.15-0.46% of 2,4,5-T, one of the phenoxy acetic acid compounds that was an active ingredient of Agent Orange, entered the body and was eliminated in the urine. CONCLUSIONS: The prospect of exposure to TCDD from Agent Orange in ground troops in Vietnam seems unlikely in light of the environmental dissipation of TCDD, little bioavailability, and the properties of the herbicides and circumstances of application that occurred. Photochemical degradation of TCDD and limited bioavailability of any residual TCDD present in soil or on vegetation suggest that dioxin concentrations in ground troops who served in Vietnam would have been small and indistinguishable from background levels even if they had been in recently treated areas. Laboratory and field data reported in the literature provide compelling evidence on the fate and dislodgeability of herbicide and TCDD in the environment. This evidence of the environmental fate and poor bioavailability of TCDD from Agent Orange is consistent with the observation of little or no exposure in the veterans who served in Vietnam. Appreciable accumulation of TCDD in veterans would have required repeated long-term direct skin contact of the type experienced by United States (US) Air Force RANCH HAND and US Army Chemical Corps personnel who handled or otherwise had direct contact with liquid herbicide, not from incidental exposure under field conditions where Agent Orange had been sprayed.

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PubMed2001

Impact of chemical warfare with agent orange on women's reproductive lives in Vietnam: a pilot study.

During the American war in Vietnam, huge quantities of the highly toxic herbicide dioxin ('Agent Orange'), were sprayed over large areas of central and south Vietnam. In addition to polluting the environment and causing cancers and other diseases in those directly exposed to it, dioxin has caused high rates of pregnancy loss, congenital birth defects and other health problems in their children. This paper reports the findings of a pilot study in the year 2000 among 30 Vietnamese women whose husbands and/or who themselves were exposed to Agent Orange. The aim was to develop research in order to explore the impact of chemical warfare on people's lives. Using the reproductive lifeline and semi-structured interviews, information was gathered on both partners' periods of exposure to Agent Orange, pregnancy outcomes, perceived health problems of children and experiences of living with handicapped children. The women had had a high number of miscarriages and premature births. About two-thirds of their children had congenital malformations or developed disabilities within the first years of life. Most of the families were poor, aggravated by impaired health in the men, the burden of caring for disabled children, and feelings of guilt and inferiority. The plight of 'Agent Orange families' is special and should be placed in its historical and political context.

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PubMed1998

Exposure to Agent Orange and occurrence of soft-tissue sarcomas or non-Hodgkin lymphomas: an ongoing study in Vietnam.

Agent Orange was the most common herbicide used in the Second Indochina War in the course of military operations in the former South Vietnam. Agent Orange is contaminated by the carcinogen 2,3,7,8-tetrachlorodibenzo-para-dioxin (TCDD) in mean concentrations of 2 mg/kg. After much dispute of a causal association between exposure to herbicides containing TCDD and occurrence of soft-tissue sarcoma and non-Hodgkin lymphoma, two simultaneous case-control studies were set up in Vietnam to examine possible relationships. Subject recruitment is ongoing, with target numbers of 150 cases of soft-tissue sarcoma and 150 cases of non-Hodgkin lymphoma and diagnoses at the Cancer Center at Ho Chi Minh City, Vietnam. Two hospital controls are matched to each case. As in other studies of cancer in persons occupationally or otherwise exposed to herbicides and their contaminants, evaluation of past exposure of the recruited subjects is among the most complicated issues. Because accurate records are usually unavailable, surrogate measures of likely exposure are often calculated. As a first approach in our studies we used the Stellman and Stellman exposure index. The index is based on matching subjects' history of residence and the information on times and locations of Agent Orange spraying recorded on HERBS tape by the U.S. Army and taking into account the distance from the spraying as well as environmental and biologic half-life of TCDD. The exposure index is calculated in two centers, New York and Hanoi, with slightly different assumptions. In addition, samples of body tissues from the subjects (20 ml blood, 2 g adipose tissue, and tumor sections in paraffin blocks) are taken and stored. Their future analysis will provide additional source of exposure assessment. Strengths and weaknesses of both exposure measures are discussed in this paper.

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PubMed2004

Assessing possible exposures of ground troops to Agent Orange during the Vietnam War: the use of contemporary military records.

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.

2,4,5-Trichlorophenoxyacetic Acid↗

PubMed1995

Agent Orange and the Vietnamese: the persistence of elevated dioxin levels in human tissues.

OBJECTIVES: The largest known dioxin contamination occurred between 1962 and 1970, when 12 million gallons of Agent Orange, a defoliant mixture contaminated with a form of the most toxic dioxin, were sprayed over southern and central Vietnam. Studies were performed to determine if elevated dioxin levels persist in Vietnamese living in the south of Vietnam. METHODS: With gas chromatography and mass spectroscopy, human milk, adipose tissue, and blood from Vietnamese living in sprayed and unsprayed areas were analyzed, some individually and some pooled, for dioxins and the closely related dibenzofurans. RESULTS: One hundred sixty dioxin analyses of tissue from 3243 persons were performed. Elevated 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) levels as high as 1832 ppt were found in milk lipid collected from southern Vietnam in 1970, and levels up to 103 ppt were found in adipose tissue in the 1980s. Pooled blood collected from southern Vietnam in 1991/92 also showed elevated TCDD up to 33 ppt, whereas tissue from northern Vietnam (where Agent Orange was not used) revealed TCDD levels at or below 2.9 ppt. CONCLUSIONS: Although most Agent Orange studies have focused on American veterans, many Vietnamese had greater exposure. Because health consequences of dioxin contamination are more likely to be found in Vietnamese living in Vietnam than in any other populations, Vietnam provides a unique setting for dioxin studies.

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