Neurology in the Vietnam War.

Between December 1965 and December 1971, the United States maintained armed forces in Vietnam never less than 180,000 men and women in support of the war. At one time, this commitment exceeded half a million soldiers, sailors, and airmen from both the United States and its allies. Such forces required an extensive medical presence, including 19 neurologists. All but two of the neurologists had been drafted for a 2-year tour of duty after deferment for residency training. They were assigned to Vietnam for one of those 2 years in two Army Medical Units and one Air Force facility providing neurological care for American and allied forces, as well as many civilians. Their practice included exposure to unfamiliar disorders including cerebral malaria, Japanese B encephalitis, sleep deprivation seizures, and toxic encephalitis caused by injection or inhalation of C-4 explosive. They and neurologists at facilities in the United States published studies on all of these entities both during and after the war. These publications spawned the Defense and Veterans Head Injury Study, which was conceived during the Korean War and continues today as the Defense and Veterans Head Injury Center. It initially focused on post-traumatic epilepsy and later on all effects of brain injury. The Agent Orange controversy arose after the war; during the war, it was not perceived as a threat by medical personnel. Although soldiers in previous wars had developed serious psychological impairments, post-traumatic stress disorder was formally recognized in the servicemen returning from Vietnam.

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.

Long overlooked historical information on Agent Orange and TCDD following massive applications of 2,4,5-T-containing herbicides, Eglin Air Force Base, Florida.

BACKGROUND: From 1961-1971, The Air Development Test Center, Eglin Air Force Base (AFB), Florida, developed, tested, and calibrated the aerial spray systems used in support of Operation RANCH HAND and the US Army Chemical Corps in Vietnam. Twenty major test and evaluation projects of aerial spray equipment were conducted on four fully instrumented test grids, each uniquely arrayed to match the needs of fixed-wing, helicopter, or jet aircraft. Each of the grids was established within the boundary of Test Area 52A of the Eglin Reservation. METHODS: The tests, conducted under climatic and environmental conditions similar to those in Vietnam, included the use of the military herbicides (Agents) Orange, Purple, White, and Blue. Approximately 75,000 kg of 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) and 76,000 kg of 2,4-dichlorophenoxyacetic acid (2,4-D) were aerially disseminated on an area of less than 3 km2 during the period 1962-1970. Data from the analysis of archived samples suggested that an estimated 3.1 kg of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), present as a contaminant, were aerially released in the test area. Because most of the vegetation had been removed before establishing the test site in 1961, there was an opportunity to follow ground-based residues independent of canopy interception, and the resulting high solar exposure of initial residues. Studies of the soils, fauna, flora, and aquatic ecosystems of the test grids and associated perimeters of Test Area C-52A (an area totally more than 8 km2) were initiated in 1969 and concluded in 1984. RESULTS AND DISCUSSION: Data from soil samples collected from 1974 through 1984 suggested that less than one percent of the TCDD that was present in soil when sampling began persisted through the ten-year period of sampling. More than 340 species of organisms were observed and identified within the test area. More than 300 biological samples were analyzed for TCDD and detectable residues were found in 16 of 45 species examined. Examination of the ecological niches of the species containing TCDD residues suggested each was in close contact with contaminated soil. Indepth field studies, including anatomical, histological and ultrastructural examinations, spanning more than 50 generations of the Beachmouse, Peromyscus polionotus, demonstrated that continual exposure to soil concentrations of 0.1 to 1.5 parts-per-billion (ng/g) of TCDD, had minimal effects upon the health and reproduction of this species. CONCLUSIONS: Since Agent Orange with its associated TCDD contaminant was aerially disseminated on the test grids, Test Area C-52A provided a 'field laboratory' for what may have happened in Vietnam, had there been no intercepting forest cover. However, in Vietnam a 'typical' mission would have disseminated 14.8 kg of 2,4,5-T/ha, most of which was intercepted by the forest canopy, versus the 876 kg 2,4,5-T/ha on the test grid at Eglin. Moreover, each hectare on the Eglin test grid received at least 1,300 times more TCDD than a hectare sprayed with Agent Orange in Vietnam. The disappearance or persistence of TCDD is dependent upon how it enters the ecosystem. Spray equipment test and evaluations missions at Eglin were generally scheduled and conducted with environmental conditions that were optimal for spray operations. This suggests that conditions favorable for dissemination of herbicide were the same conditions favorable for photodegradation of TCDD. It was likely that 99 percent of the TCDD never persisted beyond the day of application. No long-term adverse ecological effects were documented in these studies despite the massive quantities of herbicides and TCDD that were applied to the site. Reviews by the US Environmental Protection Agency and the National Academy of Sciences' Institute of Medicine did not address the fate of Agent Orange and TCDD as described in these studies from Eglin AFB, Florida.