Disposition of the Air Force Health Study (2006) / Chapter Skim
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2 Background
2 Background
Pages 20-67
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The early history of the Agent Orange controversy is then reviewed along with the first studies of Vietnam veterans' health. A detailed description of the Air Force Health Study (AFHS)
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.3 In the 1950s, the British military effectively used aerially disseminated herbicides,4 a fact that did not go unnoticed by U.S. military planners and the State Department as the situation grew more volatile in Southeast Asia (SEA)
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. The organic acid mixture used at Camp Drum was only one herbicidal candidate of more than 1,000 compounds tested during and after WWII at the Army Chemical Corps laboratories at Fort Detrick, Maryland (Midwest Research Institute, 1967)
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. Defoliant operations in a much-reduced capacity also targeted agricultural concerns considered to be potential food sources for enemy troops.10 Although the Army Corps of Chemical Engineers and the Navy were also involved in defoliant missions,11 the bulk of defoliation efforts in Operation Trail Dust12 were undertaken by a largely volunteer group of Air Force personnel who eventually became known as the Ranch Hands.
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By June 1962, the Ranch Hands were ready to fly their first tactical missions. In 1968 the Special Aerial Spray Flight received the new unit designation of 12th Special Operations Squadron (McConnell, 1970)
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. 18In a class action lawsuit initiated in 2004, more than 30 Agent Orange manufacturers are named (de Sola, 2004)
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. Other conditions under which Ranch Hands were subject to herbicide exposure included the use of herbicides as hand cleaners (efficient for grease and oil removal)
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eThere were two Agent Orange formulas used in Vietnam. The original formula was a 50:50 mix ture of 2,4-D and the n-butyl ester of 2,4,5-T.
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In response to these results, as well as increasing media reports implicating Agent Orange as a causative agent for myriad health problems, the use of 2,4,5-T was domestically restricted on April 15, 1970, and the DOD concomitantly suspended 2,4,5-T's military use (Butler, 2005)
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non-Vietnam veterans. This resulted in pressure on the VA to shift from a study of the health effects of Agent Orange to a study of the Vietnam experience.
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for measuring serum 2,3,7,8-TCDD levels -- hereafter referred to as simply serum TCDD -- which presumably could serve as a biomarker of Agent Orange exposure. With the advent of the serum TCDD assay, the CDC conducted the Agent Orange Validation Study to determine the feasibility of an Agent Orange study using both military records and serum TCDD levels as surrogates of in-theater herbicide exposure (VA, 2003)
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, it does mark the beginning of the Academy's association with the USAF's Agent Orange study. In December of 1979, the NAS Panel on the Proposed Air Force Study of Herbicide Orange convened to review the proposed protocol, and their final report was issued on May 6, 1980 (NRC, 1980)
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, which called for a 20-year follow-up of the cohort and up to six physical examination cycles, was completed in January 1982 (AFHS, 1982)
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Ranch Hand II Study -- had been given its present name: the Air Force Health Study (AFHS)
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They were assumed to be similar to Ranch Hand subjects regarding lifestyle, training profiles, and socioeconomic factors. Comparison subjects were matched to Ranch Hand subjects on age, race,32 and military occupation at a ratio as high as 1:10.33 Military occupation was divided into five categories: officer/pilot, officer/navigator, officer/ other, enlisted/flight engineer, and enlisted/other (AFHS, 1984a)
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Retrospective health data were collected for deceased (noncombat related) Ranch Hand subjects and comparison subjects through first-order next-of-kin interviews.
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tour number of airmen w / subject's duties during i th tour The TCDD weighting factor equaled 1 for post–July 1, 1965 duty and 24 for pre–July 1, 1965 duty. The rationale for it was that the herbicides used in the earlier time period (Agents Pink, Green, Purple, and early batches of Agent Orange)
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. Eventually, sera samples were collected from 150 Ranch Hand subjects and 50 comparison subjects independent of the 1987 Cycle 3 follow-up physical exam; sera were collected at Red Cross Centers in Atlanta, Cleveland, Los Angeles, and Tulsa (CDC, 1988)
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and serum TCDD level -- initial or current values. Data Collection Data from both the questionnaires and the physical examinations were collected by contracted personnel41 who were blinded to participant exposure status (AFHS, 1982, 1984a, 2005)
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. Baseline questionnaires were administered to these replacement comparison subjects by USAF personnel at the physical examination site (AFHS, 1984a)
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. Generally, earlier analyses performed sought to identify differences between Ranch Hand subjects and comparison subjects relating to both subjective and objective endpoints by group and exposure opportunity (AFHS, 1987)
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SOURCE: M Yeager, Science Applications International Corporation (SAIC)
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Category Current TCDD Body Burden Ranch Hand Subjects Unknown ≤ 10 ppt Low 15 ppt < TCDD ≤ 33.3 ppt High > 33.3 ppt Comparison Subjects ≤ 10 ppt SOURCE: AFHS, 1991b.
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Initial TCDD body burden was the basis for Model 2 and body fat percentage50 was considered a covariate. In Model 3, variation in health outcomes were evaluated for both Ranch Hand subjects and comparison subjects by lipid-adjusted initial TCDD body burden51 category (Table 2-5)
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The singular change in Model 4 for Cycle 6 was the use of the 7.6-year TCDD half-life value to extrapolate to 1987 serum TCDD levels (AFHS, 2005)
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Model 3 applied to the reproductive outcomes of both Ranch Hand subjects and comparison subjects based on current TCDD ranking (Table 2-7)
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. The 1986 update provided summary counts and death rates for Ranch Hand subjects and comparison subjects stratified by race and military occupation (AFHS, 1986)
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Selected papers produced by the investigators are addressed in the section entitled AFHS Research and the Institute of Medicine's Veterans and Agent Orange Reports. Morbidity and Mortality Study Results Participation in the Cycle 1 evaluation was on a volunteer basis even for personnel on active duty -- 15 percent of both Ranch Hand subjects and matched comparison subjects were on active duty59 at the time the Cycle 1 study was implemented, and 17 percent of Ranch Hand subjects and 19 percent of matched comparison subjects held Federal Aviation Administration Certificates indicating active participation in the aviation sector (AFHS, 1984a)
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were also not observed to be more prevalent among Ranch Hand subjects. Many of the differences observed between Ranch Hand subjects and comparison subjects were based on self-reported measures (e.g., more Ranch Hand subjects perceived their health to be poor)
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. Trends in mortality were associated with age: Ranch Hand officers born between 1905 and 1935 were found to have a better mortality experience than comparison subjects and a worse mortality experience than comparison subjects for those Ranch Hand subjects born after 1935 (AFHS, 1984b)
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of verified and suspected neoplasms. Ranch Hand subjects were found to be experiencing more coordination abnormalities than comparison subjects, and after controlling for insecticide exposure, a significant increasing trend was observed for coordination abnormalities among enlisted Ranch Hand subjects.
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Cycle 4 analyses indicated that Ranch Hand subjects perceived their health status to be poorer than that of comparison subjects. Investigators noted that this result may have been biased as subjects were aware of TCDD body burden results and thus those with higher levels (Ranch Hand subjects)
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Ranch Hand subjects were also more likely than comparison subjects to require insulin control of their diabetes. Time to diabetes onset was directly associated with current serum TCDD levels among Ranch Hand subjects.
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. Mean TSH was significantly higher for Ranch Hand subjects versus comparison subjects as was luteinizing hormone for Ranch Hand officers only versus comparison subjects (Model 1)
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Results for unadjusted cause-specific analyses indicated that Ranch Hand subjects did not differ significantly from comparison subjects. After adjusting for rank and military occupation -- there were too few non-Caucasian subjects to adjust for race -- there were still no significant trends 71Three of four neural tube defects identified were cases of spina bifida (IOM, 1996)
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However, this finding was not statistically significant and was not suggestive of an herbicide effect -- the majority resulted from alcoholic liver disease. In view of the data collected between 1979 and December of 1993, AFHS investigators concluded that there were no significant differences between Ranch Hand subjects and comparison subjects for overall all-cause mortality, nor were any differences in group mortality (officer/enlisted or flyer/nonflyer)
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SOURCES: M Blancas, Air Force Health Study, personal communication, No vember 4, 2005; DTIC, 2000, 2001, 2002, 2003, 2004, 2005.
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A total of $1,612,000 is assigned to these and other data analysis and support tasks.74 The documentation and organization activities were apparently planned as a routine part of the study's shutdown and were not related to the Veterans and Agent Orange–series report recommendations concerning the AFHS discussed in the Chapter 1. In Chapters 3 and 4, the committee offers several recommendations regarding how the data assets should be documented and organized.
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L 102-4 required the VA to contract with the NAS to independently review all available scientific data pertaining to the health effects of herbicides used during the Vietnam War (not limited to Agent Orange)
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Fourteen of the 230 studies were related to the Air Force Health Study. Thirty-two outcomes or categories of outcomes were identified.
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The previously reviewed (IOM, 1994) AFHS 1990 report of increased risk of nonmelanomic skin cancer among Ranch Hand subjects contributed to the category change of skin cancer from limited or suggestive evidence of no association to inadequate or insufficient evidence to determine whether an association exists.
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. These indicated an increased prevalence of and a decreased time to onset of type 2 diabetes was associated with dioxin exposure among Ranch Hand subjects.
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Additional information on, and reviews of, the AFHS reports and papers may be found in the text of the Veterans and Agent Orange reports referenced in the Appendix. In the period since the Agent Orange Act of 1991 was passed, the AFHS has contributed to the establishment of a presumptive service connection82 for type 2 diabetes in Vietnam veterans and for spina bifida in their offspring.
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2001. Serum dioxin and cognitive functioning among veterans of Operation Ranch Hand.
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1994. Risk of testicular cancer associated with surrogate measures of Agent Orange exposure among Vietnam veterans on the Agent Orange Registry.
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1999. Agent Orange: Actions Needed to Improve Communica tions of Air Force Ranch Hand Study Data and Results.
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PowerPoint presentation before the Committee on the Disposition of the Air Force Health Study, Washing ton, DC. Michalek JE, Tripathi RC.
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Cabin John, MD: Seven Locks Press. Wolfe WH, Principal Investigator, Air Force Health Study.
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