Post-Vietnam Dioxin Exposure in Agent Orange-Contaminated C-123 Aircraft (2015) / Chapter Skim
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3 Air Force Use of the C-123 Provider: Background and Sampling Data
3 Air Force Use of the C-123 Provider: Background and Sampling Data
Pages 27-46
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From page 27... ...
Designed by the Chase Aircraft Company in New Jersey and built by Fairchild Industries in Hagerstown, Maryland, the C-123 was utilized in Vietnam for a range of tactical missions including transportation of military personnel and equipment, evacuation of wounded soldiers, and supply operations for advanced combat positions. This chapter provides background information about the use of C-123 Provider aircraft to spray herbicides in Vietnam and their subsequent use by the AF Reserve personnel in the United States.
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From page 28... ...
Operation Ranch Hand Historically, the approximately 1,300 AF personnel involved in the UC-123 fixed-wing aircraft spray activities in Vietnam between 1962 and 1971 (codenamed TABLE 3-1 Military Use of Herbicides in Vietnam (1961–1971) Code Name Chemical Constituentsa Formulations with TCDD Contamination Pink 60% n-butyl ester, 40% isobutyl ester of 2,4,5-T Green n-butyl ester of 2,4,5-T Purple 50% n-butyl ester of 2,4-D, 30% n-butyl ester of 2,4,5-T, 20% isobutyl ester of 2,4,5-T Orange 50% n-butyl ester of 2,4-D, 50% n-butyl ester of 2,4,5-T Orange II 50% n-butyl ester of 2,4-D, 50% isooctyl ester of 2,4,5-T Formulations Without TCDD Contamination White Acid weight basis: 21.2% triisopropanolamine salts of 2,4-D, 5.7% picloram Blue powder Cacodylic acid (dimethylarsinic acid)
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From page 29... ...
Defoliation spray missions were carried out by highly-trained three-person crews of male Ranch Hand (RH) personnel consisting of a pilot, copilot/navigator, and a spray equipment console operator.
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From page 30... ...
ORH crews had the potential for exposure when flying with the cockpit windows or rear cargo door open, flying through previously sprayed airspace, or by exposure to broken or malfunctioning spray lines or spillage from storage tanks. The extent of exposure of ORH ground crews or C-123 flight personnel in Vietnam has not been documented, but estimates of exposure based on days of exposure, percentage of skin exposed, the concentration of herbicide formulations, and serum TCDD concentrations, show that this population had the potential for even higher exposures than flight crews (Michalek et al., 1995)
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From page 31... ...
The C-123s transferred to TAGs or TASs were used between 1972 and 1982 by AF Reserve personnel for military airlifts, medical transport, and cargo transport in the United States and internationally. Thirteen former ORH C-123s were sold through the Military Assistance Program to other countries, including El Salvador, Korea, Laos, the Philippines, South Vietnam, and Thailand (detailed information is included in Table B-1 in Appendix B)
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From page 32... ...
During routine flight operations, flight crews sat on the floor, reclined, kneeled, sat on bucket seats, or crawled while completing their duties or doing maintenance work. Crew members routinely touched
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From page 33... ...
CONCERNS ARISE ABOUT EXPOSURE TO HERBICIDES Air Force Health Study In 1979, a commitment was made by the AF to study potential adverse health effects in ORH personnel (AFHS, 1982)
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From page 34... ...
This Institute of Medicine (IOM) committee is charged with examining the potential exposure of AF Reserve personnel who worked and trained aboard C-123 aircraft that were used by ORH personnel for herbicide spray operations in Vietnam.
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From page 35... ...
The potential exposures for AF Reserve personnel were evaluated strictly on that basis by this committee, not by direct extrapolation from the health experience of ORH personnel. RESIDUAL CHEMICALS IN FORMER ORH AIRCRAFT Existing Sampling Data "Patches" Sampling Data (1975, 1979)
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From page 36... ...
. The AF reported that the test results were low enough to "indicate no health hazard." TABLE 3-2 Interior Sampling for Phenoxy Herbicides of C-123 Planes Used in Operation Ranch Hand C-123 Tail Source Number 2,4,5-T 2,4-D Location Herbicide Air Samples (mg/m3)
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From page 37... ...
390 450 Interior rear frame 55-4571 490 540 Interior floor-1 100 110 Interior floor-2 360 520 Interior floor-3 310 250 Interior floor-4 260 180 Front bulkhead wall 600 1,600 Interior ceiling (between wings) 720 100 Interior rear frame-1 840 780 Interior rear frame-2 980 1,200 Interior rear frame-3 a The air sampling methods used on these two occasions differed, so results are not fully comparable.
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From page 38... ...
(see Table 3-3) , and were determined to likely "be representative of other locations of limited traffic near the agent orange spraying equipment," but not considered to be "indicative of the surface contamination throughout the entire cargo area of the aircraft" (USAF, 1994)
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From page 39... ...
13 Interior rear frame 55-4571 18 Interior floor-1 27 Interior floor-2 21 Interior floor-3 4.3 Interior floor-4 7.1 Front bulkhead wall 1.0 Interior ceiling (between wings) 9.3 Interior rear frame-1 32 Interior rear frame-2 10 Interior rear frame-3 a Itmight have been preferable to consider TCDD results in terms of Toxicity Equivalency uotients Q (TEQs)
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From page 40... ...
provides a record of all 40 ORH aircraft that have been identified. In May 1996, two wipe samples were gathered from the top of the auxiliary power unit and from the metal railing on top of the tank from one or two planes (no specification of aircraft tail number specified)
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From page 41... ...
. TCDD concentrations in surface wipe samples collected in C-123s between 1994 and 2009 ranged from 1,440 ng/m2 in 1994 down to 1 ng/m2 in 2009.
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From page 42... ...
These variations lead to uncertainty in estimating the actual exposures of the AF Reservists, but confirm that TCDD exposure would be expected. While some samples were collected in areas that are suggested to have had little traffic, the work patterns of the AF Reservists and the different configurations of equipment and personnel used in flight assignments led to the committee's judgment that contact with these surfaces carried a risk, though not quantifiable, of harmful exposure to the AF Reservists.
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From page 43... ...
. In addition to these TCDD wipe samples, air samples were collected in 2009 and analyzed for TCDD, all of which were non-detects, and samples from various media were collected and analyzed for 2,4-D and 2,4,5-T in 1979 and 2009 (see Table 3-2)
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From page 44... ...
Air Samples Air sampling methodologies vary depending upon whether the target compounds are expected to be present in the vapor or particle-bound phase. Particles are typically captured using filters that lack sorption capacity for vapor phase compounds.
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From page 45... ...
Two of the three samples revealed air concentrations of 2,4-D and 2,4,5-T that were near or above estimated vapor saturation concentrations of the acid moieties. However, the 2,4-D and 2,4,5-T esters have higher vapor pressures than the acids, and analysis of a scrape sample did reveal the presence of ester forms.
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From page 46... ...
These samples were collected to assess whether there was a significant exposure risk to personnel who were going to be involved in the destruction and recycling of the aircraft over a short period of time, rather than for exposures continuing over years, as was the situation for the AF Reservists. Also, given the low vapor pressure of TCDD, the unknown sampling temperature (vapor pressure declines with temperature)
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