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Response to Commentary: Post-Vietnam military herbicide exposures in UC-123 Agent Orange spray aircraft
Environmental Research 131 (2014) 215–216
Contents lists available at ScienceDirect
Environmental Research journal homepage: www.elsevier.com/locate/envres
Response to Commentary: Post-Vietnam military herbicide exposures in UC-123 Agent Orange spray aircraft Peter A. Lurker a, Fred Berman b, Richard W. Clapp c, Jeanne Stellman d a
Germantown Consultants, LLC, Germantown, OH, USA The Center for Research on Occupational and Environmental Toxicology, Oregon Health and Science University, Portland, OR, USA c Boston University School of Public Health, Boston, MA, USA d Department of Health Policy & Management, Mailman School of Public Health, Columbia University, 600 West 168th Street, 6th floor, New York, NY, USA b
We are grateful that Karl Nieman applauds our ability to carry out difficult modeling of dioxin exposures using sparse historical data from the 34 UC-123 aircraft used in Vietnam to spray some 20 million gallons of herbicides. These aircraft were returned to service in the United States without effective decontamination (Lurker et al., 2014). We, however, reject Nieman's contention that we failed to consider all available data and his implication that we rummaged through the data to cherry-pick those that exaggerated exposures. Nieman contends that 1994 Air Force surface wipe data of the spray aircraft nicknamed “Patches” (Weisman and Porter, 1994) should not have been used to model dermal-oral exposure. He quotes the authors' statement that “[the samples] were likely to be representative of other locations of limited traffic near the agent orange [sic] spraying equipment… from locations somewhat protective of routine crew movement and routine historical maintenance… [and] are most likely not indicative of the surface contamination throughout the entire cargo area of the aircraft.” First, both the survey and the author statement were not made with regard to past exposures in UC-123 Air Force Reserve crew and maintenance staff, but were directed at ensuring that the Museum restoration staff should not be exposed to dioxins still present in Patches. Exposure scenarios for these groups will differ markedly. Further, it turns out the Weisman and Porter conjecture that the samples were “most likely not indicative of surface contamination throughout the aircraft” was found NOT to be the case. In 2009 dioxin contamination was measured throughout UC-123 spray planes (other than Patches) in each of 16 areas swiped (Table B-1, USAF, 2009). Further, our analysis did not only use these three data points. We combined the 1994 data with the sixteen points measured in 2009 from other mothballed spray aircraft (Table B-1, USAF, 2009). Environmental Protection Agency (2014) analytical software yielded a log-normal distribution, giving us confidence in the appropriateness of aggregating the data. All the surface wipes were taken some 25–40 years post-Vietnam. The great majority of points came from aircraft stored for decades in the hot desert environment. We contend that not only are the three Weisman
DOI of original article: http://dx.doi.org/10.1016/j.envres.2014.03.022 http://dx.doi.org/10.1016/j.envres.2014.03.037 0013-9351/& 2014 Elsevier Inc. All rights reserved.
samples valid, they, in fact, better represent the surface concentrations of the aircraft in the post-Vietnam period than do the 16 surface interior samples of 2009 because of the thermal and UV degradation that occurred from 1994 to 2009. Nonetheless, we chose to include the degraded and more aged wipes in order to be very conservative in our modeling. Our conservative approach also included using the smallest number (3) for hand-to-mouth transfer events in the scenarios for dermal-oral route of entry. May et al. (2002), whose work is the basis for the US Army dermal-oral exposure models (USACHPPM, 2009), used 3–24 events. The Environmental Protection Agency (1997) uses 0–24 events for general industrial workers. Our models did not entail the profligate use of biased data designed to show overexposure, and, most important, despite our conservative approach, the dermal-oral model still produced exposures well above accepted standards for maintainers and crew. Nieman would also have it appear that the rear area sampled by Weisman and Porter (1994) was remote. In fact, it was heavily utilized by cargo and flight crews. The aircraft was equipped with a ramp in the rear for loading and unloading large cargo, such as medical transport patients, a major use of the contaminated UC-123s. Further, the 1000 gallon spray tank, compressor and manifold with three lines to spray nozzles under each wing on and beneath the centerline of the aircraft, were located in the front compartment and were major sources of contamination through spills and leaks. One of us (P.A.L.) personally inspected Patches in 2011 and observed that the front compartment floor slopes downward to a 3/4-in. gap completely crossing the cargo compartment. The bilge is below the cargo compartment gap. The rear cargo compartment slopes upward. Thus, it would be expected that the major concentration of contamination would have been in the front of the aircraft and would not have transferred up the rear ramp. Nieman asserts that we purposefully neglected to use 49 high quality samples in our analyses. Our exhaustive review of available data did not identify such a dataset. These data were not cited nor relied upon by the Air Force in its “Consultative Letter” on potential exposures in the UC-123s (Smallwood, 2012). The Veterans Administration does not cite it among the documents it lists for scientific support of its position on this issue (DVA, 2014).
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P.A. Lurker et al. / Environmental Research 131 (2014) 215–216
These data were not provided as evidence in a lawsuit brought against the government for reneging on its contracted sale of the UC-123s because of contamination (General Service Administration, 2000). They are not included in the electronic datasets that accompany the 2009 Air Force report on the planes (Appendix I, USAF, 2009). The only reference we could find to a 45 ng/m2 surface wipe contamination level was as the result of a composite sample taken in 1995 (p. 12–13, USAF, 2009). That document also lists two other samples, taken in 1996, but provides only mass and not surface area of contaminant. Thus none of these samples provided sufficient information to be utilizable in our analysis. Further, P.A.L. expended a good deal of due diligence while a civil service employee of the Air Force working on this issue to gather all available data and this dataset was not made available then. Nieman questions our modeling of airborne dioxin. He considers it “noteworthy” that we failed to mention that one of the three air samples taken in 1979 at Westover Air Force Base yielded a non-detect value. Why is one non-detect noteworthy? It does not negate positive detection in two different areas of the aircraft. Our model used the two measured values of 2,4,5-T to extrapolate the corresponding concentration of dioxin likely to have been present, based on known contamination levels. We did not average our findings, but presented a range and that range exceeded the only available standard (Lurker et al., 2014). What is noteworthy is that these samples were drawn nearly a decade post-spraying and were still positive for the parent herbicides! Nieman is correct that we ought to have mentioned that 2009 air samples drawn in the interior of the sun-baked aircraft were negative for dioxin. We did mention that exterior wipe samples were negative, as expected, and should have, for completeness, cited the expected negative air samples as well. Temperatures inside the aircraft were extremely high and there was ultraviolet leakage into the interior. When P.A.L. was an industrial hygienist at Davis-Monthan Air Force Base, Arizona, he measured skin temperature of the stored aircraft in 1984 as high as 160 1F and observed light entering the interior of the stored aircraft. There is
no reason to expect low levels of dust-adsorbed dioxin to be detected in air samples under those conditions. In sum, Nieman, an Air Force contractor, has expressed doubts about our data sources that are unsupported by the available facts. We maintain that post-Vietnam UC-123 crews were indeed likely to have been exposed to dioxin, especially since our exposure models did not include models for either dermal absorption or inhalation, two other important routes-of-entry for toxic substances. Current Veterans Administration policy needs to be revised to recognize, medically treat and compensate those harmed by this exposure, just as the Vietnam veterans who served in Vietnam itself.
References Board of Contract Appeals, General Services Administration, 2000. Western Aviation Maintenance, Inc. v. General Services Administration. Washington, DC. Retrieved from: 〈http://www.gsbca.gsa.gov/appeals/w1416522.txt〉. Lurker, P.A., Berman, F., Clapp, R.W., Stellman, J.M., 2014. Post-Vietnam military herbicide exposures in UC-123 Agent Orange spray aircraft. Environ. Res. 130, 34–42, http: //dx.doi.org/10.1016/j.envres.2014.02.004. May, L.M., Gaborek, B., Pitrat, T., Peters, L., 2002. Derivation of risk based wipe surface screening levels for industrial scenarios. Sci. Total Environ. 288, 65–80. Smallwood, M.E., 2012. UC-123 Agent Orange Exposure Assessment, Post-Vietnam (1972–1982). USAF School of Aerospace Medicine, Wright-Patterson AFB, OH U.S. Army Center for Health Promotion and Preventive Medicine (USACHPPM), 2009. Technical Guide 312 Health Risk Assessment Methods and Screening Levels for Evaluating Office Worker Exposures to Contaminants on Indoor Surfaces Using Surface Wipe Data. Aberdeen Proving Ground, Maryland. U.S. Department of the Air Force (USAF), 2009. Final – Dioxin and Herbicide Characterization of UC-123K Aircraft – Phase I. Select Engineering Services, Hill Air Force Base, Utah. U.S. Environmental Protection Agency, 1997. Region III, Guidance for Assessing Wipe Samples, July 9, 1997. U.S. Environmental Protection Agency (EPA), 2014. ProUCL Software. Available at: 〈http://www.epa.gov/osp/hstl/tsc/software.htm〉 (retrieved 15.03.14). U.S. Department of Veterans Affairs (DVA), 2014. Scientific Review of Agent Orange in C-123 Aircraft. 〈http://www.publichealth.va.gov/exposures/agentorange/loca tions/residue-c123-aircraft/scientific-review.asp〉 (retrieved 13.03.14). Weisman, W.H. and Porter, R.C., 1994. Review of Dioxin Sampling Results from C-123 Aircraft: U.S. Department of the Air Force. Consultative Letter. Brooks Air Force Base, Texas.
Contents lists available at ScienceDirect
Environmental Research journal homepage: www.elsevier.com/locate/envres
Response to Commentary: Post-Vietnam military herbicide exposures in UC-123 Agent Orange spray aircraft Peter A. Lurker a, Fred Berman b, Richard W. Clapp c, Jeanne Stellman d a
Germantown Consultants, LLC, Germantown, OH, USA The Center for Research on Occupational and Environmental Toxicology, Oregon Health and Science University, Portland, OR, USA c Boston University School of Public Health, Boston, MA, USA d Department of Health Policy & Management, Mailman School of Public Health, Columbia University, 600 West 168th Street, 6th floor, New York, NY, USA b
We are grateful that Karl Nieman applauds our ability to carry out difficult modeling of dioxin exposures using sparse historical data from the 34 UC-123 aircraft used in Vietnam to spray some 20 million gallons of herbicides. These aircraft were returned to service in the United States without effective decontamination (Lurker et al., 2014). We, however, reject Nieman's contention that we failed to consider all available data and his implication that we rummaged through the data to cherry-pick those that exaggerated exposures. Nieman contends that 1994 Air Force surface wipe data of the spray aircraft nicknamed “Patches” (Weisman and Porter, 1994) should not have been used to model dermal-oral exposure. He quotes the authors' statement that “[the samples] were likely to be representative of other locations of limited traffic near the agent orange [sic] spraying equipment… from locations somewhat protective of routine crew movement and routine historical maintenance… [and] are most likely not indicative of the surface contamination throughout the entire cargo area of the aircraft.” First, both the survey and the author statement were not made with regard to past exposures in UC-123 Air Force Reserve crew and maintenance staff, but were directed at ensuring that the Museum restoration staff should not be exposed to dioxins still present in Patches. Exposure scenarios for these groups will differ markedly. Further, it turns out the Weisman and Porter conjecture that the samples were “most likely not indicative of surface contamination throughout the aircraft” was found NOT to be the case. In 2009 dioxin contamination was measured throughout UC-123 spray planes (other than Patches) in each of 16 areas swiped (Table B-1, USAF, 2009). Further, our analysis did not only use these three data points. We combined the 1994 data with the sixteen points measured in 2009 from other mothballed spray aircraft (Table B-1, USAF, 2009). Environmental Protection Agency (2014) analytical software yielded a log-normal distribution, giving us confidence in the appropriateness of aggregating the data. All the surface wipes were taken some 25–40 years post-Vietnam. The great majority of points came from aircraft stored for decades in the hot desert environment. We contend that not only are the three Weisman
DOI of original article: http://dx.doi.org/10.1016/j.envres.2014.03.022 http://dx.doi.org/10.1016/j.envres.2014.03.037 0013-9351/& 2014 Elsevier Inc. All rights reserved.
samples valid, they, in fact, better represent the surface concentrations of the aircraft in the post-Vietnam period than do the 16 surface interior samples of 2009 because of the thermal and UV degradation that occurred from 1994 to 2009. Nonetheless, we chose to include the degraded and more aged wipes in order to be very conservative in our modeling. Our conservative approach also included using the smallest number (3) for hand-to-mouth transfer events in the scenarios for dermal-oral route of entry. May et al. (2002), whose work is the basis for the US Army dermal-oral exposure models (USACHPPM, 2009), used 3–24 events. The Environmental Protection Agency (1997) uses 0–24 events for general industrial workers. Our models did not entail the profligate use of biased data designed to show overexposure, and, most important, despite our conservative approach, the dermal-oral model still produced exposures well above accepted standards for maintainers and crew. Nieman would also have it appear that the rear area sampled by Weisman and Porter (1994) was remote. In fact, it was heavily utilized by cargo and flight crews. The aircraft was equipped with a ramp in the rear for loading and unloading large cargo, such as medical transport patients, a major use of the contaminated UC-123s. Further, the 1000 gallon spray tank, compressor and manifold with three lines to spray nozzles under each wing on and beneath the centerline of the aircraft, were located in the front compartment and were major sources of contamination through spills and leaks. One of us (P.A.L.) personally inspected Patches in 2011 and observed that the front compartment floor slopes downward to a 3/4-in. gap completely crossing the cargo compartment. The bilge is below the cargo compartment gap. The rear cargo compartment slopes upward. Thus, it would be expected that the major concentration of contamination would have been in the front of the aircraft and would not have transferred up the rear ramp. Nieman asserts that we purposefully neglected to use 49 high quality samples in our analyses. Our exhaustive review of available data did not identify such a dataset. These data were not cited nor relied upon by the Air Force in its “Consultative Letter” on potential exposures in the UC-123s (Smallwood, 2012). The Veterans Administration does not cite it among the documents it lists for scientific support of its position on this issue (DVA, 2014).
216
P.A. Lurker et al. / Environmental Research 131 (2014) 215–216
These data were not provided as evidence in a lawsuit brought against the government for reneging on its contracted sale of the UC-123s because of contamination (General Service Administration, 2000). They are not included in the electronic datasets that accompany the 2009 Air Force report on the planes (Appendix I, USAF, 2009). The only reference we could find to a 45 ng/m2 surface wipe contamination level was as the result of a composite sample taken in 1995 (p. 12–13, USAF, 2009). That document also lists two other samples, taken in 1996, but provides only mass and not surface area of contaminant. Thus none of these samples provided sufficient information to be utilizable in our analysis. Further, P.A.L. expended a good deal of due diligence while a civil service employee of the Air Force working on this issue to gather all available data and this dataset was not made available then. Nieman questions our modeling of airborne dioxin. He considers it “noteworthy” that we failed to mention that one of the three air samples taken in 1979 at Westover Air Force Base yielded a non-detect value. Why is one non-detect noteworthy? It does not negate positive detection in two different areas of the aircraft. Our model used the two measured values of 2,4,5-T to extrapolate the corresponding concentration of dioxin likely to have been present, based on known contamination levels. We did not average our findings, but presented a range and that range exceeded the only available standard (Lurker et al., 2014). What is noteworthy is that these samples were drawn nearly a decade post-spraying and were still positive for the parent herbicides! Nieman is correct that we ought to have mentioned that 2009 air samples drawn in the interior of the sun-baked aircraft were negative for dioxin. We did mention that exterior wipe samples were negative, as expected, and should have, for completeness, cited the expected negative air samples as well. Temperatures inside the aircraft were extremely high and there was ultraviolet leakage into the interior. When P.A.L. was an industrial hygienist at Davis-Monthan Air Force Base, Arizona, he measured skin temperature of the stored aircraft in 1984 as high as 160 1F and observed light entering the interior of the stored aircraft. There is
no reason to expect low levels of dust-adsorbed dioxin to be detected in air samples under those conditions. In sum, Nieman, an Air Force contractor, has expressed doubts about our data sources that are unsupported by the available facts. We maintain that post-Vietnam UC-123 crews were indeed likely to have been exposed to dioxin, especially since our exposure models did not include models for either dermal absorption or inhalation, two other important routes-of-entry for toxic substances. Current Veterans Administration policy needs to be revised to recognize, medically treat and compensate those harmed by this exposure, just as the Vietnam veterans who served in Vietnam itself.
References Board of Contract Appeals, General Services Administration, 2000. Western Aviation Maintenance, Inc. v. General Services Administration. Washington, DC. Retrieved from: 〈http://www.gsbca.gsa.gov/appeals/w1416522.txt〉. Lurker, P.A., Berman, F., Clapp, R.W., Stellman, J.M., 2014. Post-Vietnam military herbicide exposures in UC-123 Agent Orange spray aircraft. Environ. Res. 130, 34–42, http: //dx.doi.org/10.1016/j.envres.2014.02.004. May, L.M., Gaborek, B., Pitrat, T., Peters, L., 2002. Derivation of risk based wipe surface screening levels for industrial scenarios. Sci. Total Environ. 288, 65–80. Smallwood, M.E., 2012. UC-123 Agent Orange Exposure Assessment, Post-Vietnam (1972–1982). USAF School of Aerospace Medicine, Wright-Patterson AFB, OH U.S. Army Center for Health Promotion and Preventive Medicine (USACHPPM), 2009. Technical Guide 312 Health Risk Assessment Methods and Screening Levels for Evaluating Office Worker Exposures to Contaminants on Indoor Surfaces Using Surface Wipe Data. Aberdeen Proving Ground, Maryland. U.S. Department of the Air Force (USAF), 2009. Final – Dioxin and Herbicide Characterization of UC-123K Aircraft – Phase I. Select Engineering Services, Hill Air Force Base, Utah. U.S. Environmental Protection Agency, 1997. Region III, Guidance for Assessing Wipe Samples, July 9, 1997. U.S. Environmental Protection Agency (EPA), 2014. ProUCL Software. Available at: 〈http://www.epa.gov/osp/hstl/tsc/software.htm〉 (retrieved 15.03.14). U.S. Department of Veterans Affairs (DVA), 2014. Scientific Review of Agent Orange in C-123 Aircraft. 〈http://www.publichealth.va.gov/exposures/agentorange/loca tions/residue-c123-aircraft/scientific-review.asp〉 (retrieved 13.03.14). Weisman, W.H. and Porter, R.C., 1994. Review of Dioxin Sampling Results from C-123 Aircraft: U.S. Department of the Air Force. Consultative Letter. Brooks Air Force Base, Texas.