Correspondence DO WE REALLY NEED A PROGRAM TO COMPENSATE AVIATION CREWMEMBERS FOR RADIATION-INDUCED CANCER? Dear Editors: IN “RADIATION Exposure of Aviation Crewmembers and Cancer,” Bramlitt and Shonka (2015) recommend a worker’s compensation program specific to aviation crew members. The basis for this recommendation includes: • The worst-case dose to crewmembers from a terrestrial gamma ray flash of approximately 30 mSv exceeds the 20 mSv average annual limit adopted by the FAA and ICRP; • The use of the Interactive Radio-epidemiological Program (IREP) program in the compensation program developed by the National Institute for Occupational Safety and Health (NIOSH) set up to compensate former DOE nuclear weapons facility workers establishes a precedent for this type of program • Crewmembers are occupationally exposed to radiation and some of them get cancer; and • IREP results to hypothetical crewmembers indicate a 50% probability of causation at the 99th percentile of acute myeloid leukemia at 1.67 mSv and 40 mSv for females and males, respectively.
Should dose to crewmembers be more accurately measured as the authors suggest? Absolutely. Is it a topic worthy of future study? Absolutely. However, the existence of an occupational dose and causing disease are not the same. Exceeding a dose limit established by an agency such as the FAA, NRC, ICRP, etc., in no way proves or even suggests that a radiogenic disease is likely to occur. Occupational hazards are not typically regulated at levels just beneath those that are likely to produce disease; rather, large safety factors are built in such that limits are established at dose levels much lower than those likely to result in disease. That the IREP code produces the results cited in no way supports the conclusion that 1.67 or 40 mSv results in acute myeloid leukemia, or any other leukemia or cancer, in anybody. NIOSH uses the IREP code as part of a public policy program established by Congress and signed into law by President Clinton; it has very little in common with science-based radiation dosimetry or radiation risk projection. Finally, the authors suggest that their recommendations are more likely to draw a favorable response if fostered by 0017-9078/15/0 Copyright © 2015 Health Physics Society DOI: 10.1097/HP.0000000000000286
the health physics community. The last thing we should be doing is promoting more radiation-phobia by encouraging former aviation crewmembers with cancer to be compensated as victims based on the linear non-threshold (LNT) model of radiation carcinogenesis, a model which consistently fails to accurately portray the impact of low radiation doses on human populations. Fostering this type of approach to radiation safety and related policy has resulted in approximately 1,600 evacuation-related fatalities following Fukushima and causes doctors to withhold CT scans and other useful medical procedures from patients, all in the name of avoiding low radiation doses that are benign at worst or hormetic at best. The author declares no conflicts of interest. ALAN FELLMAN
3758 Carrisa Lane Olney, MD 20832 [email protected]
REFERENCE Bramlitt ET, Shonka JJ. Radiation exposure of aviation crewmembers and cancer. Health Phys 108:76–86; 2015.
RESPONSE TO FELLMAN Dear Editors: FELLMAN BELIEVES we claim, in short: 1) over-limit doses cause radiogenic diseases, 2) a 1.67 mSv dose causes cancer, and 3) compensation for aircraft crewmembers (ACM) should be based on the LNT model. We made no such claims. We counter them below to earn his support and that of other readers for our principal claim: ACM dosimetry is warranted. But first, some background. In 1986, the FAA decided against ACM dosimetry based on quarterly dose from galactic cosmic rays (GCR) not being likely to exceed 3.12 mSv, a level requiring dosimetry under NRC regulations. The FAA has never altered that decision, even though it later classified ACM as radiation workers and set dose limits. In 1990, the FAA advised ACM to track their exposures considering dose for 32 representative flights. Since 1993, it offers online programs to calculate dose for specific flights. The programs give good estimates for GCR alone, but they are seldom used as the
www.health-physics.com
631
Copyright © 2015 Health Physics Society. Unauthorized reproduction of this article is prohibited.
632
Health Physics
needed input data and computer resources are unavailable to most ACM on the job. The FAA consistently says GCR is the only source that contributes significantly to ACM dose. We discussed other sources: solar proton events (SPE), solar neutron events (SNE), and solar gamma rays (SGE) and terrestrial gamma ray flashes (TGF). The FAA says SPE occasionally add dose to some higher latitude flights, but the amount does not significantly alter GCR dose. We reported that SPE frequency by U.S. satellites is seven times greater than assumed by FAA; further, the frequency of transpolar flights has increased exponentially since 2001. We reported SNE and SGE have been detected at Earth, and their intensities are greatest at lower latitude flight levels in daylight, but doses from them are unknown. We reported ACM and passengers can get up to 100 mSv from a TGF. They can get 0.54 mSv from a terrestrial neutron flash (TNF). Thundercloud gamma ray events (TGE) are as energetic as TGF but last much longer, and doses from them are unknown. Counterclaim #1: We wrote that 100 mSv is over the 20 mSv limit adopted by FAA, but we never wrote that it is a cause of radiogenic disease. It is 32 the 3.12 mSv level FAA used in 1986 to deny ACM dosimetry. It is 200 the 0.5 mSv limit FAA adopts for pregnant women. We wrote of sources for which there is no dose estimate. We wrote five recommendations for FAA, and three of them relate to ACM dosimetry. We say doses over limits are a reason for ACM dosimetry, not a cause for disease. Counterclaim #2: The 1.67 mSv dose comes from IREP, which was created to compensate DOE workers. There is uncertainty with dose effects and uncertainty with doses the DOE workers received; thus, IREP gives the benefit of doubt to those workers. IREP is available online for use by anyone. We tried it on two hypothetical ACM with radiogenic cancers that are seen in excess in ACM, and IREP returned 1.67 mSv as the lowest annual dose over 30 y necessary for one of the ACM to qualify for compensation, had the ACM been a DOE worker. IREP decisions granting compensation do not mean a particular cancer was caused by radiation exposure. IREP is extremely liberal in the favor of workers by requiring 50% POC at or above the 1% upper bound. Counterclaim #3: Nowhere do we mention the LNT model. We recommended an IREP-type program be applied
June 2015, Volume 108, Number 6
to ACM, as they have been denied dosimetry by the FAA. Some ACM get additional dose from the intermittent sources during their careers. We believe a program comparable to IREP is more justifiable for FAA workers than for DOE workers. The complaint of “promoting more radiation phobia” should be directed to the agencies responsible for IREP. However, IREP was reviewed by many experts. Their approval was sufficient for 30% of the DOE workers to receive Federal compensation for their work. In closing, our Note quotes from the 1985 HPJ: “Valid dosimetry data should be obtained and recorded now to avoid the need to reconstruct doses” (Bramlitt 1985). Three decades later, there still is no requirement for dosimetry, even though all ACM are exposed to GCR and a few are also exposed to radiation from the sun by SPE, SNE, and SGE and from thunderstorms by TGF, TNF, and TGE. The probability of dose by an intermittent source is likely to be small, but when one occurs, it impacts passengers as well as the ACM. For a quantitative measure of significance, the worldwide collective dose for ACM by GCR exposure alone and for nuclear fuel cycle workers was 2,200 person-Sv in 1992 with 36% due to ACM; it decreased to 1,560 person-Sv in 2001, but the ACM role jumped to 58%. The collective dose for ACM continues to increase even without including the intermittent sources. As a final claim, dosimetry is primarily needed for ACM, and secondarily for society as it may lead to a better understanding of the consequences of radiation exposures. The authors declare no conflicts of interest. EDWARD T. BRAMLITT JOSEPH J. SHONKA
Albuquerque, NM [email protected]
REFERENCE Bramlitt ET. Commercial aviation crewmember radiation doses. Health Phys 49(5):945–948; 1985.
www.health-physics.com
Copyright © 2015 Health Physics Society. Unauthorized reproduction of this article is prohibited.
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Should dose to crewmembers be more accurately measured as the authors suggest? Absolutely. Is it a topic worthy of future study? Absolutely. However, the existence of an occupational dose and causing disease are not the same. Exceeding a dose limit established by an agency such as the FAA, NRC, ICRP, etc., in no way proves or even suggests that a radiogenic disease is likely to occur. Occupational hazards are not typically regulated at levels just beneath those that are likely to produce disease; rather, large safety factors are built in such that limits are established at dose levels much lower than those likely to result in disease. That the IREP code produces the results cited in no way supports the conclusion that 1.67 or 40 mSv results in acute myeloid leukemia, or any other leukemia or cancer, in anybody. NIOSH uses the IREP code as part of a public policy program established by Congress and signed into law by President Clinton; it has very little in common with science-based radiation dosimetry or radiation risk projection. Finally, the authors suggest that their recommendations are more likely to draw a favorable response if fostered by 0017-9078/15/0 Copyright © 2015 Health Physics Society DOI: 10.1097/HP.0000000000000286
the health physics community. The last thing we should be doing is promoting more radiation-phobia by encouraging former aviation crewmembers with cancer to be compensated as victims based on the linear non-threshold (LNT) model of radiation carcinogenesis, a model which consistently fails to accurately portray the impact of low radiation doses on human populations. Fostering this type of approach to radiation safety and related policy has resulted in approximately 1,600 evacuation-related fatalities following Fukushima and causes doctors to withhold CT scans and other useful medical procedures from patients, all in the name of avoiding low radiation doses that are benign at worst or hormetic at best. The author declares no conflicts of interest. ALAN FELLMAN
3758 Carrisa Lane Olney, MD 20832 [email protected]
REFERENCE Bramlitt ET, Shonka JJ. Radiation exposure of aviation crewmembers and cancer. Health Phys 108:76–86; 2015.
RESPONSE TO FELLMAN Dear Editors: FELLMAN BELIEVES we claim, in short: 1) over-limit doses cause radiogenic diseases, 2) a 1.67 mSv dose causes cancer, and 3) compensation for aircraft crewmembers (ACM) should be based on the LNT model. We made no such claims. We counter them below to earn his support and that of other readers for our principal claim: ACM dosimetry is warranted. But first, some background. In 1986, the FAA decided against ACM dosimetry based on quarterly dose from galactic cosmic rays (GCR) not being likely to exceed 3.12 mSv, a level requiring dosimetry under NRC regulations. The FAA has never altered that decision, even though it later classified ACM as radiation workers and set dose limits. In 1990, the FAA advised ACM to track their exposures considering dose for 32 representative flights. Since 1993, it offers online programs to calculate dose for specific flights. The programs give good estimates for GCR alone, but they are seldom used as the
www.health-physics.com
631
Copyright © 2015 Health Physics Society. Unauthorized reproduction of this article is prohibited.
632
Health Physics
needed input data and computer resources are unavailable to most ACM on the job. The FAA consistently says GCR is the only source that contributes significantly to ACM dose. We discussed other sources: solar proton events (SPE), solar neutron events (SNE), and solar gamma rays (SGE) and terrestrial gamma ray flashes (TGF). The FAA says SPE occasionally add dose to some higher latitude flights, but the amount does not significantly alter GCR dose. We reported that SPE frequency by U.S. satellites is seven times greater than assumed by FAA; further, the frequency of transpolar flights has increased exponentially since 2001. We reported SNE and SGE have been detected at Earth, and their intensities are greatest at lower latitude flight levels in daylight, but doses from them are unknown. We reported ACM and passengers can get up to 100 mSv from a TGF. They can get 0.54 mSv from a terrestrial neutron flash (TNF). Thundercloud gamma ray events (TGE) are as energetic as TGF but last much longer, and doses from them are unknown. Counterclaim #1: We wrote that 100 mSv is over the 20 mSv limit adopted by FAA, but we never wrote that it is a cause of radiogenic disease. It is 32 the 3.12 mSv level FAA used in 1986 to deny ACM dosimetry. It is 200 the 0.5 mSv limit FAA adopts for pregnant women. We wrote of sources for which there is no dose estimate. We wrote five recommendations for FAA, and three of them relate to ACM dosimetry. We say doses over limits are a reason for ACM dosimetry, not a cause for disease. Counterclaim #2: The 1.67 mSv dose comes from IREP, which was created to compensate DOE workers. There is uncertainty with dose effects and uncertainty with doses the DOE workers received; thus, IREP gives the benefit of doubt to those workers. IREP is available online for use by anyone. We tried it on two hypothetical ACM with radiogenic cancers that are seen in excess in ACM, and IREP returned 1.67 mSv as the lowest annual dose over 30 y necessary for one of the ACM to qualify for compensation, had the ACM been a DOE worker. IREP decisions granting compensation do not mean a particular cancer was caused by radiation exposure. IREP is extremely liberal in the favor of workers by requiring 50% POC at or above the 1% upper bound. Counterclaim #3: Nowhere do we mention the LNT model. We recommended an IREP-type program be applied
June 2015, Volume 108, Number 6
to ACM, as they have been denied dosimetry by the FAA. Some ACM get additional dose from the intermittent sources during their careers. We believe a program comparable to IREP is more justifiable for FAA workers than for DOE workers. The complaint of “promoting more radiation phobia” should be directed to the agencies responsible for IREP. However, IREP was reviewed by many experts. Their approval was sufficient for 30% of the DOE workers to receive Federal compensation for their work. In closing, our Note quotes from the 1985 HPJ: “Valid dosimetry data should be obtained and recorded now to avoid the need to reconstruct doses” (Bramlitt 1985). Three decades later, there still is no requirement for dosimetry, even though all ACM are exposed to GCR and a few are also exposed to radiation from the sun by SPE, SNE, and SGE and from thunderstorms by TGF, TNF, and TGE. The probability of dose by an intermittent source is likely to be small, but when one occurs, it impacts passengers as well as the ACM. For a quantitative measure of significance, the worldwide collective dose for ACM by GCR exposure alone and for nuclear fuel cycle workers was 2,200 person-Sv in 1992 with 36% due to ACM; it decreased to 1,560 person-Sv in 2001, but the ACM role jumped to 58%. The collective dose for ACM continues to increase even without including the intermittent sources. As a final claim, dosimetry is primarily needed for ACM, and secondarily for society as it may lead to a better understanding of the consequences of radiation exposures. The authors declare no conflicts of interest. EDWARD T. BRAMLITT JOSEPH J. SHONKA
Albuquerque, NM [email protected]
REFERENCE Bramlitt ET. Commercial aviation crewmember radiation doses. Health Phys 49(5):945–948; 1985.
www.health-physics.com
Copyright © 2015 Health Physics Society. Unauthorized reproduction of this article is prohibited.
■■
