RRVA AMIC Working Cancer Hypothesis

The RRVA Aviator Medical Issues Committee

Introduction.  In late 2019, the Red River Valley Fighter Pilot Association (RRVA) organized its Aviator Medical Issues Committee (AMIC). The AMIC is composed of RRVA members at large that include a group of retired and practicing medical professionals, each with deep aerospace medicine training, knowledge, and experience. The mission of the AMIC is to address health issues of vital interest to RRVA membership and all military aviators. To date, the AMIC is focusing its analytic and advocacy effort on two issues. Of those two issue areas, the one discussed in this statement is our work addressing the incidence and causes of cancers that seem to disproportionately afflict US military aviators.

 

Background.  RRVA members know of numerous squadron mates and flying partners diagnosed with cancer at a rate that seemed to exceed average cancer incidence rates in the US general population.[1] Consequently, in Fall 2019 RRVA conducted an informal survey of its 3,400+ members.[2] The AMIC processed 894 survey responses for a return rate of 26% (2019 membership level). Of the 894 responses, 500 (56%) disclosed respondent personal cancer incidence; 13% of this group indicated multiple personal cancer diagnoses. The majority of respondents (RRVA members only) knew one or more fellow military aviators stricken with cancer. The survey’s most frequently reported cancer was melanoma; second was prostate cancer. The 2019 RRVA pilot cancer survey was not a classic scientific study that utilized rigorous design norms and methodologies.

 

In May 2021, the US Air Force School of Aerospace Medicine (USAFSAM) at Wright-Patterson AFB, OH, reported findings of its Air Force aviator retrospective cohort study.[3] This study assessed Air Force fighter aviators relative to other Air Force officers and the U.S. general population with multiple control groups. The study cohort included 34,976 active duty fighter aviators who served from 1 June 1970 to 31 December 2004 contrasted to a control group of 386,190 Air Force officers that served 1970-2004.[4] The USAFSAM study indicated prostate cancer had a significantly higher incidence among fighter aviators than both of the study’s control groups.[5] Other cancers with higher occurrence among fighter aviators included melanoma. These two USAFAM study outcomes corroborated RRVA’s 2019 Pilot Cancer Survey findings. Other cancers identified by the USAFSAM May 2021 study with higher incidence/mortality rates among Air Force aviators rates were thyroid, testicular, and non-Hodgkin lymphoma. The study is praiseworthy for its synoptic discussion of potential military operating causal factor attribution including cohort study biases.

 

Other Studies.  The RRVA AMIC is grateful to the Air Force for its willingness to conduct its first-ever cohort study regarding cancer incidence and mortality. Of note, the Defense Health Agency of the Department of Defense is conducting the U.S. military’s first-ever multi-service aviator and aviation support personnel study.[6] The DHA is under Congressional mandate to report the findings of this study in 2022.[7]

 

Discussion. The RRVA AMIC’s working hypothesis of cancers in U.S. military aviators is: that a likely complicated, not entirely understood, nor fully researched chronic occupational exposures to ionizing radiation (IoR) and non-ionizing radiation (NIoR) coalesce with factors potentially unique to military operating environments to elevate cancer incidence/mortality among U.S. military aviators. The operationalization of this hypothesis may account for elevated aviator cancer incidence/mortality documented by a recent U.S. Air Force aviator cancer study.[8]

 

 

Within that hypothesis are other notions about how Airmen, Sailor, and Marine aviators operate their aircraft that plays a central role in significantly higher rates of cancer incidence/mortality than non-flying military members and the U.S. general population. For example, present commercial aviation IoR exposures  focus on the operating altitude envelopes of airline aircraft. In contrast, military aircraft may operate in that same altitude band, but in the case of high-performance fighter aircraft, operate up to and beyond 50,000 feet. As depicted in Figure 1., IoR is principally composed of four distinct types of particles with a range of penetration/absorption properties that may impact human health.

 

U.S. military aviators likely exceed by significant margins what are considered safe annual aerial IoR exposure.[9] IoR exposure levels are proven to increase as altitude increases, with IoR exposure doses at 50,000+ feet several times higher than flight at/near sea level. While Air Force, Navy, and Marine Corps aviators may experience numerous other toxic exposures, RRVA’s working hypothesis focuses on the extensive IoR literature and the absence of a similar body of NIoR exposure scientific and medical scholarship. There is extensive human health and safety IoR literature. In contrast there is a paucity of NIoR exposure research. Here, the U.S. atomic weapon attacks of World War II cast a long shadow over atomic science and radiation medicine.[10] The long established Life Span Study (LSS) documents and researches at scale the multi-generational health effects of Japanese civilians exposed to acute and chronic radiation effects in those attacks.[11]

 

To return to the AMIC working hypothesis, there is another important aspect of IoR that IoR and so far only IoR has the properties sufficient to cause chemical changes at the cellular level to provoke the formation of cancer cells in humans. The literature extensively documents the cellular activities and interactions of human tissues with decaying radioactive particles that pass through those tissues.[12] Figure 2 is a simplified depiction of the complex direct and indirect impacts of radioactive particles as they decay and interact with cellular DNA. At the cellular level, this is the origin story of IoR established by the literature that demonstrates how IoR exposure can and does cause cancer.

 

 

Zooming out to another element of the working hypothesis, the RRVA AMIC takes no position on the diversity of literature that describes low dose/low dose rate state of art medical and scientific thought.[13] However, the AMIC notes a lack of broad scientific/medical consensus on the implications of lifelong chronic low dose/low dose rate IoR exposure.[14] The reasons for this lack of consensus are varied. However, it is noteworthy that in the literature, researchers frequently opine that improved understanding of low dose/low dose rate exposures requires larger study populations.[15] The population size of military aviators stretching back 40+ years not only makes for study cohorts with a helpfully large “n” (study population) but that n is the also the exposure cohort whose health effects need to be better understood to ascertain cancer cause/effect linkages in U.S. military aviators.[16]

 

Next, foreign regulators used studies and implemented measures to minimize foreign airline aircrew exposures today.[17] Foreign regulators hold that foreign aircrews receive annual IoR dosages that put them into the category of personnel occupationally exposed to ionizing radiation.[18] Interestingly, U.S. military aviators routinely operate at altitudes and block hour levels that exceed those documented in previous studies and by foreign regulation.[19] Some of these studies are mentioned in the USAFSAM May 2021 study. This points to another concern, that of IoR dosimetry. For example, select aerial IoR exposure data can be found in FAA Advisory Circular 120-61B.[20] Additionally, the FAA’s web-based Civil Aviation Research Institute (CARI) 7/7A exposure planning tool offers a more robust aircrew exposure planning baseline. Elsewhere in the world, airline companies are required to track crew exposure.[21] No such exposure tracking occurs among U.S. military aviators who face the same environmental hazards.[22] Meanwhile, many U.S. military aviator aircrews accumulate at least the same, perhaps more IoR exposure as foreign airline crews. Neither the CARI model or FAA data should be construed as authoritative predictions of aircrew cancer incidence and/or mortality. In the U.S., radiation exposure mitigation across the federal government is regulated by the Environmental Protection Agency.[23] The FAA and the U.S. military do not track aviator annual IoR exposure nor do they impose annual exposure limitations.[24]

 

Pivoting toward NIoR, the other component of the AMIC’s working hypothesis, Figure 3 illustrates the energy spectrum that depicts the relationship of NIoR to IoR. Unlike the substantial body of medical and scientific knowledge associated with IoR, NIoR research is limited and lacks rigor.  

 

The AMIC’s working hypothesis contains another premise: under-studied NIoR may constitute undocumented radiation exposure. If validated by research, NIoR energy levels may be another causal path for DNA damage at the cellular that elevates cancer risk in aviators with chronic NIoR exposure. The most common sources of concentrated NIoR energy in the military operating environments are termed high-power emitters (HPEs). HPEs are ubiquitous in military operating environments since the mid-1960s.  Within the AMIC’s working hypothesis, aircraft RADARs and aircraft onboard jamming equipment constitute the bulk of the hypothesized NIoR exposure path.[25] Data which measures exposure levels from the HPE equipment that is common throughout military operating environments does not exist. Measurement and study of HPE radiation output effects as discussed here on cellular function and DNA will be new research. Until that research is conducted, absence of NIoR HPE exposure and dosage effects evidence should not be construed as evidence of absence of potential NIoR harm. 

 

 

Referring to Figure 3 and another premise of the AMIC’s NIoR working hypothesis is the region of the energy spectrum where ultraviolet light is located.[26] While science documents the effects of ultraviolet light exposure on the ground on humans, there likely is an incomplete understanding of measured effect data as to the ultraviolet protection properties of most military aircraft windshields; specifically, those with large bubble-type canopies common to U.S. fighter aircraft.[27] The statistically higher occurrence of melanoma in the RRVA Pilot Cancer Survey and USAFSAM May 21 aviator cancer study may be linked to these unmeasured effects and their partially understood effects on Airmen, Sailors, and Marines that operate under those aircraft canopies. Some researchers assert melanoma cancer outcomes are actually driven by lifestyle and not aviation factors. Research does not yet rule in/out lifestyle among aviation exposure.[28]

 

Beyond IoR and NIoR, there could be numerous other causes for higher cancer incidence/mortality among military aviators in the varied military operating environments.[29] The RRVA AMIC takes no position on the weighting of any confounding factors in specific studies, but we do acknowledge the role and presence of these factors among military aviators. In a larger sense, confounding factor variation does not prefigure for analytic disregard; rather, it begs for numerous vertical cause/effect studies. Consequently, the burden of proof for lack of toxic health effect or demonstration of health and safety does not lie with military aviators.

 

Legislative Priorities.  The USAFSAM May 2021 study is the first study at scale among military aviators and other control groups that may provide certain Veterans stricken with prostate cancer, melanoma, non-Hodgkin lymphoma as a means to obtain Veterans Administration service connection awarded for their cancer. The crux is that cancer seldom manifests during military service or in the year that follows separation and/or retirement. Absent any tool such as the USAFSAM May 2021 study, Veteran military aviators are at significant disadvantage in proving up on the claim for disability and compensation. Meanwhile, military aviators who suffer with cancers other than prostate, melanoma, and non-Hodgkin lymphoma which they perceive is connected to military service, are left to confront numerous and perhaps insurmountable case development challenges in constructing a fully developed case that successfully yields service connection.

 

The U.S. Air Force, DOD’s largest and most diverse aviation service studied aviator cancers and determined that yes, Air Force aviators suffer cancers at rates of incidence and mortality higher than their non-rated service peers and the U.S. general population. On this basis alone, DOD should direct the Defense Health Agency to undertake numerous aviator cancer nexus studies. However, if as empowered by Section 750 of the FY21 NDAA Secretary of Defense Austin does not direct the conduct of nexus studies, RRVA will advocate for legislation that requires DOD to conduct nexus studies in military aviators. Military aviator cancer nexus studies should examine sources of known and/or unknown carcinogens that are unique to, or found exclusively in military operating environments.

 

Elsewhere, rather than a narrow strategy that seeks to assist each Veteran aviator with his/her direct service connection, RRVA is proposing a broader strategy that yields a presumptive class.[30] This presumptive class, a proposed Military Aviators Cancers presumptive class would be Congressionally enacted for a group of cancers identified by DOD as caused by exposure to carcinogens in the military operating environment.

 

Conclusion.  Nexus research of carcinogens in military operating environments will not discourage aviators from military flying. Rather, research will reinforce existing notions of care for the aviator forces of the Air Force, Navy, and Marine Corps. Importantly, data-driven approaches will enable Veterans to obtain the health monitoring, ongoing care, and connection that are products of their service and which they need to assist them in early cancer diagnosis and treatments to improve outcomes. RRVA is committed to those results. RRVA asks Congress, Department of Defense, and Veteran’s Administration to equally commit to delivery of military aviator cancer care and where appropriate, VA claim service connection.

 

Questions concerning this article, efforts of the RRVA AMIC, or assistance filing a VA claim for a cancer with military aviator service connection, email medical@river-rats.org or email the RRVA AMIC Director at vince.alcazar@river-rats.org.

 



[1] Amplification: A reference to annual cancer incidence data collected and published by the US National Institutes of Health, Washington, D.C. in its report(s).

[2] The RRVA 2019 Pilot Cancer Survey Report is available via email request to: medical@river-rats.org.

[3] Amplification: RRVA AMIC did not collaborate with the Air Force in this study. To obtain a copy of the study titled “Cancer Incidence and Mortality among Fighter Aviators who Served on Active Duty in the U.S Air Force between 1970 and 2004: A Comparison to Other Officers and the General U.S. Population,” contact the 711 Human Performance Wing, Epidemiology Consult Service Division, 2510 5th Street, Building 840, WPAFB, OH 45433, or under the Medical Tab of the RRVA home page.

[4] Author Note: Not included in the study were all other Air Force training, bomber, tanker, transport, helicopter, and rescue aviators. A population count of this large unstudied aviator group likely exceeds 100,000. Also unstudied were cancer incidence and mortality outcomes for fighter aviators that served in the Air National Guard and Air Force Reserve. Former Air Force fighter aviators who separated from active duty but sought care for cancer diagnosis and treatment in private care are uncounted. The study’s cohort begins in 1970, decades prior to the establishment of Veterans’ Administration and  Department of Defense cancer registries and active cancer diagnosis tracking programs. The cumulative effect of the above considerations creates the potential for a significant Air Force aviator cancer undercount. Unstudied were Air Force aviators in the post-9/11 generation after 2004 to 2021. Study authors did utilize other methods to broaden their analytic reach.

[5] Clarification: The other control group within the USAFSAM May 2021 study was U.S. general population cancer incidence/mortality data.

[6] Amplification: Titled Section 750 of the Fiscal Year 2021 National Defense Authorization Act (FY21 NDAA).

[7] Author Note: A key provision within the Section 750 FY21 NDAA enactment is that after a review of the CY2021 DHA multi-service aviator cancer study, the Secretary of Defense may direct follow-on next study(s) to identify underlying environmental cancer-cause relationships.

[8] Cancer Incidence and Mortality among Fighter Aviators who Served on Active Duty in the U.S Air Force between 1970 and 2004: A Comparison to Other Officers and the General U.S. Population, May 21, 2021, 711 Human Performance Wing, U.S. Air Force School of Aerospace Medicine (USAFSAM), Wright-Patterson AFB, Dayton, OH.

[9] Explanation: this statement is not supported by data. However, this is the field operations use case that ought to be the focus of concerted scientific and medical analysis to map IoR exposure levels. In essence, this is the root of RRVA’s advocacy for environmental study and cancer nexus research among U.S. military aviators.

[10] Long Term Radiation-Related Health Effects in a Unique Human Population: Lessons Learned from the Atomic Bomb Survivors of Hiroshima and Nagasaki, by Douple, et. al., Journal of Disaster Medicine and Public Health Preparedness, Vol. 5, Suppl. 1, pgs. S122-S132.

[11] An Evaluation of Theories Concerning The Health Effects of Low Dose Radiation Exposures, Massachusetts Institute of Technology student paper, June 2021, by Elizabeth Wei, pgs. 40-49.

[12] Nonlinearity of Radiation Health Effects, Myron Pollycove, U.S. Nuclear Regulatory Commission, Washington, D.C., Journal of Environmental Health Perspectives, Vol. 106, Suppl. 1, February 1998, pgs. 363-368.

[13] A Critical  Shift In Low-Dose Radiation Research and Communication, by Susan Gallier, Nuclear News, July 2021, American Nuclear Society, pgs. 55-59.

[14] Ibid., Elizabeth Wei.

[15] Cancer in Fighters, unpublished manuscript/working papers, Dr. Charles Shurlow, USAF, pgs. 1-45.

[16] Amplification: Readers may recall America’s two atomic weapon detonations in WWII and ask how is that some aspect of radiation exposure is still not well understood. Space here does not permit a sweeping tour of the literature and explanation for this apparent paradox. Suffice to say that the actual population of exposures of the full spectrum of radionuclides is not as large as a layman might assume; this is its own sort of blessing. While the associated science is hardly stagnant, advances mainly in cellular biology suggest exposure measurement technology and study biases may be larger than low dose exposure effects. This does not mean there is no harm at the lose dose end of the overall exposure spectrum. Instead, it suggests the inherent noise of some research tools and methods may drown out the underlying exposure risk signal.

[17] Radiation Exposure, by Mario Pierobon, Flight Safety International paper, February 27, 2019, accessed online November 9, 2021 at https://flightsafety.org/asw-article/radiation-exposure

[18] Effects of Cosmic Radiation In Aircraft: A Discussion About Aircrew Over South America, Journal of Aerospace Technology Management, Vol. 4, No. 2, pgs. 220-221, April-June 2013, by Federico, et. al.,

[19] Amplification: in U.S. military aviation, there are no published block flying hour annual limitations. Aircraft operating altitudes are dictated by individual aircraft operating manual, field, fleet, service, mission-specific guidance, or some/all of the above. In commercial aviation, operating altitudes are dictated by company daily flight planning. Commercial pilot annual flying time is governed across the world by associated national rules informed as flying hour maximums for rest and fatigue mitigation.

[21] United Nations Scientific Committee of the Effects of Atomic Radiation, 2008 Report Volume 1, United Nations, New York, New York ,pg. 228, para. 53. Detail: During periods of lower solar radiation, exposure risks actually rise due to an offsetting increase in galactic radiation exposure to neutron particle decay, most pronounced at the highest altitudes of aircraft travel and across the polar regions.

[22] See unpublished manuscript, Advances in Atmospheric Radiation Measurements and Modeling Needed To Improve International Air Safety, submitted to the Space Weather Journal December, 2014, by Tobiska et. al., pgs. 4-5.

[23] It Is Time to Move Beyond the Linear No-Threshold Theory For Low Dose Radiation Protection by John Cardelli II and Brant Ulsh, Dose-Response International Journal, July-September 2018, pg. 1.

[24] Author note: biological harm associated with IoR exposure regarding tissue effect is measured by Sieverts. See CDC online radiation term dictionary: https://www.cdc.gov/nceh/radiation/emergencies/glossary.htm

[25] Amplification: The reader may succeed in locating studies performed in the last 40 years on military RADAR and civilian workers. Owing to the their small study population, lack of provision for confounding (variations in gender, age, overall health, childhood exposures, etc.) factors, and questionable data processing methods, most NIoR studies that exist today cannot form any credible exposure to health correlation foundation. For further discussion see Epidemiology of Health Effects of Radiofrequency Exposure, International Commission for Non-Ionizing Radiation Protection Standing Committee on Epidemiology, by Ahlbom, et. al., Environmental Medicine Vol 112, Number 17, December 2004pgs. 1743-1746.

[26] Incidence of Cancer Among Licensed Commercial Pilots Flying North Atlantic Routes by Gudmundsdottir, Hrafnkelsson, and Rafnsson, Journal of Environmental Health, Volume 16, Issue 86, 2017. Author Note: In this paper, ultraviolet “A” (UV-A) and ultraviolet “B” (UV-B) are grouped together. However, some research suggests that much of UV-B is attenuated by engineered windshield/canopy material while approximately 50% of UV-A passes through windshield/canopy glass and aircrew uniforms. See also,  The Risk of Melanoma in Airline Pilots and Cabin Crew, Journal of the American Medical Association at: https://jamanetwork.com/journals/jamadermatology/fullarticle/1899248

[27] The Risk of Melanoma in Airline Pilots and Cabin Crew, Journal of the American Medical Association accessed online November 9, 2021 at: https://jamanetwork.com/journals/jamadermatology/fullarticle/1899248

[28] Ibid., Gudmundsdottir, Hrafnkelsson, and Rafnsson.

[29] New Information on Radiogenic Cancer Risks Since BEIR VII by David Pawel, Radiation Protection Division, U.S. Environmental Protection Agency, ISCORS Conference presentation, November 9, 2015 accessed November 8, 2021 at: http://www.iscors.org/doc/david-pawel-11-9-2015.pdf

[30] Author Note: This approach would assist Veterans in satisfying the VA service connection requirements found in 38CFR, § 3.302, 3.303, 3.304, and more importantly, presumptive class requirements as stipulated in § 3.309 presumptive class service connection.


 
 

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