Program of the 1998 Annual Meeting,Cosmic Radiation Exposure of Airline Crews, Passengers and Astronauts
April 1-2, 1998
Setting the Framework
Lawrence W. Townsend, Chairman
Program Overview
Lawrence W. Townsend,
University of Tennessee
Overview of Radiation Environments and Human Exposure
John W. Wilson,
NASA Langley Research Center
Human exposures to ionizing radiation have been vastly altered by developing technology in the last century. This has been most obvious in the development of radiation generating devices and the utilization of nuclear energy. But even air travel has had its impact on human exposure. Human exposure increases with advancing aircraft technology as a result of the higher operating altitudes reducing the protective cover provided by the Earth’s atmosphere from extraterrestrial radiations. This increase in operating altitudes is taken to a limit by human operations in space. Less obvious is the changing character of the radiations at higher altitudes. The associated health risks are less understood with increasing altitude due to the increasing complexity and new field components found in high altitude and space operations.
Biological Effects of Cosmic Radiation: Deterministic and Stochastic
Eleanor A. Blakely,
Lawrence Berkeley National Laboratory
Our basic understanding of the biological responses to cosmic radiations comes in large part from an international series of ground-based laboratory studies, where accelerators have provided the source of representative charged particle radiations. Most of the experimental studies have been performed using acute exposures to a single radiation type at relatively high doses and dose rates. However, most exposures in flight occur from low doses of mixed radiation fields at low-dose rates. This session will provide an overview of existing pertinent data and its limitations.
Radiation Exposure Assessment: Space and High Altitude Aircraft
Stanley Curtis,
Chairman
Radiation Measurements in Low-Earth Orbit: U.S. and Russian Results
Gautam D. Badhwar,
NASA Johnson Research Center
Space radiation presents a serious short- and long-term threat to the health of low-Earth orbiting crew members. The long-term health risk arises from the increased probability of cancer incidence after radiation exposure. The short-term risk arises from exposure to a sudden burst of particles from the sun that can effect the mission. We review the measurements of radiation dose due to trapped belt particles, galactic cosmic radiation, and solar energetic particles as observed by the United States and Russian human missions, and discuss the implications of more recent measurements, jointly made by the United States and Russia during the last six NASA Mir missions, on expected exposures for crew of the International Space Station.
Radiation Exposure for Human Mars Exploration
Lisa Simonsen &
John W. Wilson,
NASA Langley Research Center
An overview of radiation exposure estimates resulting from past Mars exploration mission analyses will be presented. Limitations on those analyses are improved environmental models, improved computational procedures, and uncertainties in risk estimation procedures. The impact of future improvements on astronaut risk estimates and limitation will be discussed.
Overview of Aircraft Radiation Exposure and Recent ER-2 Measurements
Paul Goldhagen,
U.S. Department of Energy
Crews working on present-day jet aircraft are estimated to receive one of the highest average equivalent doses of any occupationally exposed group in the United States. Crews of future high-speed commercial aircraft flying at higher altitudes may be even more exposed. Present calculations of such exposures are uncertain because knowledge of important components of the radiation field comes only from theoretical predictions. To help reduce these uncertainties for high-altitude flight, NASA and the U.S. Department of Energy started the Atmospheric Ionizing Radiation (AIR) project. The measurement part of the AIR project is an international collaboration of 12 laboratories placing 14 instruments on multiple flights of a NASA ER-2 aircraft. The AIR ER-2 measurements will be described and some preliminary results will be presented.
British Airways Measurement of Cosmic Radiation Exposure on Concorde Supersonic Transport
Michael Bagshaw,
British Airways
Monitoring equipment for ionizing radiation is installed in the Concorde supersonic transport aircraft, which flies at altitudes around 18 km (59,000 feet). British Airways has been measuring and monitoring cosmic radiation exposure of flight crew since the aircraft entered service in 1969 and much data has been derived. Techniques for measuring the cosmic radiation field continue to be developed and British Airways works closely with the U.K. National Radiological Protection Board in refining estimates of crew exposure. Examining data for October 1996, the average dose rate measured by the aircraft equipment was 14.1 µSv h-1 against the estimate from CARI-3Q of 9.5 µSv h-1. Using passive dosimeters to measure non-neutron and neutron components separately, the rate was 12.8 µSv h-1. The apparent underestimation of the effective dose by CARI-3Q by about a third is also seen in our studies of high-latitude ultra-long haul routes flown by the Boeing 747-400 between London and Tokyo. In this case, passive dosimetry gives effective dose rates in the order of 6 µSv h-1 against the estimate for a typical profile of 3.7 µSv h-1. Nonetheless, no British Airways flight crew approach the control level or dose limit recommended by the International Commission on Radiological Protection.
Radiation Exposure Assessment: Commercial Aircraft
Keran O’Brien,
Chairman
Potential Radiation Doses to Passengers and Crew of Supersonic Transports
Alexander Chee,
The Boeing Company
A tissue equivalent proportional counter (TEPC) flown at 65,000 to 70,000 feet between latitudes 18 degrees north to 60 degrees north and between longitudes 122 degrees west to 100 degrees west recorded ionizing radiation dose and lineal-energy spectra including neutron effects. Neutron dose equivalents which were calculated based on ICRP Publication 60 recommendations showed that radiation dose from neutrons was a significant but highly variable contributor to total dose equivalent. The variation in the dose equivalent was due mainly to a small number of high lineal-energy events produced by high-energy neutrons and not to a large number of lower-energy neutrons. For purposes of personnel dose monitoring, this indicates that whereas short-term doses from individual flights must be measured with personal dosimeters, long-term doses from many flights may be estimated using computer code calculations. Radiation dose equivalent calculations using the FAA’s CARI-4 computer code are made for several city pairs. Combining the TEPC results and the CARI-4 calculations, a range of potential doses is estimated.
NIOSH/FAA Measurements
Martha Waters,
National Institute of Occupational Safety and Health
The National Institute for Occupational Safety and Heath, in collaboration with the Federal Aviation Administration, is conducting several studies of aircraft cabin exposures and health outcomes among female flight attendants. Cosmic radiation is being measured on 32 commercial aircraft flights using a tissue-equivalent proportional counter. Results are presented from the first eight flights, with doses ranging from 5 to 33 µSv per flight. The NIOSH studies in progress will be briefly described.
Factors Affecting Cosmic Ray Exposures in Civil Aviation
Gerry Kendall,
National Radiological Protection Board, United Kingdom
Primary cosmic rays are exotic particles. Many are from sources at immense distances and their energies can be far greater than those generated in man-made accelerators. A complex series of interactions, starting far beyond the Earth’s atmosphere determine the way in which cosmic rays are transformed into the particles which deliver doses to passengers and crew in civil aircraft. These doses are determined by altitude, latitude and by solar activity.
European Measurements of Air Crew Exposure to Cosmic Radiation
Hans-Georg Menzel,
European Commission, Belgium
For more than 5 y, the European Commission has been supporting research into scientific and technical aspects of cosmic-ray dosimetry at flight altitudes in civil radiation. This is in response to increased public interest and concern and in anticipation of European and forthcoming national legislation to regard exposure of aircraft crew as occupational exposure, following the recommendations of ICRP Publication 60. The ongoing work within a total of three multipartner research contracts is based on a comprehensive approach including measurements with dosimetric and spectrometric instruments during flights, at high mountain altitudes and in the field of a high-energy radiation reference field at CERN as well as cosmic-ray transport calculations. The paper will present an overview on results obtained. It will demonstrate that the knowledge on radiation fields and on exposure data has been substantially consolidated and that the available data provide an adequate basis for dose assessments of aircrew.
Canadian Measurements of Air Crew Radiation Exposures
Pamela Tume,
Royal Military College of Canada
During flight, jet aircrews are exposed to a complex mixed radiation field producing higher dose and dose equivalent rates than typically encountered on the ground. Owing to a revision of the risk estimates for neutron radiation exposure, worldwide research interest has focused upon assessing the health consequences and conducting limited in-flight radiation dosimetry. This study is the first comprehensive investigation of the in-flight radiation field on Canadian-based routes and of the annual exposure of Canadian-based commercial aircrew. The current data indicate that most Canadian-based domestic and international aircrew will exceed the 1 mSv recommended annual ICRP public limit and are well below the proposed ICRP occupational limit of 20 mSv y-1.
Epidemiology
Jerome S. Puskin,
Chairman
Epidemiology Studies of Commercial Aircraft Crews
John D. Boice, Jr.,
International Epidemiology Institute
Few epidemiologic studies have been conducted of pilots and air crews. Potential occupational hazards facing personnel who travel frequently at high altitudes include exposure to increased levels of cosmic rays (which may reach 3 to 6 mSv y-1), airplane fuel (and components such as benzene), passive smoking, and other factors associated with the aircraft industry. In addition, traveling across time zones disrupts sleep patterns and biological rhythms. Slight increases in breast cancer reported among flight attendants, for example, might be related to homonal disruption or delayed pregnancy. Ongoing studies in the Nordic countries and in Germany will be discussed. Statistical issues related to the power of low dose studies to provide meaningful data on potential risks will also be covered.
Twenty-Second Lauriston S. Taylor Lecture on Radiation Protection and Measurements
Introduction of the Lecturer, Sarah Donaldson
From Chimney Sweeps to Astronauts: Cancer Risks in the Workplace, Eric J. Hall
Current Regulatory Programs
R.J. Michael Fry,
Chairman
Dose Limits for Astronauts
Warren K. Sinclair,
National Council on Radiation Protection and Measurements
Radiation exposures to individuals in space can greatly exceed natural radiation exposure on earth and possibly normal occupational radiation exposures as well. Consequently, procedures limiting exposures would be necessary. Limitations were proposed by the Radiobiological Advisory Panel of the National Academy of Sciences/National Research Council in 1970. This panel recommended short term limits to avoid deterministic effects and a single career limit (of 4 Sv) based on a doubling of the cancer risk in men aged 35 to 55. Later, when risk estimates for cancer had increased and were recognized to be age and sex dependent, the NCRP, in its report 98 in 1989, recommended a range of career limits based on age and sex from 1 to 4 Sv. NCRP is again in the process of revising recommendations for astronaut exposure. Partly because risk estimates have increased further and partly to recognize trends in limiting radiation exposure occupationally on the ground. The result of these considerations is likely to be similar short-term limits for deterministic effects but modified career limits.
Cosmic Radiation Exposure During Air Travel: Guidance Provided by the Federal Aviation Administration
Wallace Friedberg,
Federal Aviation Administration
Air carrier crew members are occupationally exposed to ionization radiation, principally from galactic cosmic radiation. In an Environmental Protection Agency document, “Radiation Protection Guidance to Federal Agencies for Occupational Exposure” (Federal Register V.52, No.17, January 1987), it is recommended that individuals occupationally exposed to radiation and managers of activities involving radiation should be instructed on the basic risks to health from ionizing radiation and on basic radiation protection principles. The presentation will be a review of instructional material provided by the Federal Aviation Administration concerning in-flight radiation exposure and current estimates of effective radiation doses received on air carrier flights.
Regulatory Control of Air Crew Exposure to Cosmic Radiation: The European Approach
Ian R. McAulay,
Trinity College, Dublin
It has been known for many years that exposure to cosmic radiation increases as height above the Earth’s surface increases and that this exposure is responsible for a radiation dose to the crew and passengers of aircraft. The International Commission on Radiological Protection has recommended that attention be paid to the need for radiological protection of civil air crew of jet aircraft because of their occupational exposure to cosmic radiation. The most recent European Directive on Basic Standards of Radiation Protection for workers and the public sets out the requirement for member states of the European Union to assess and regulate the exposure of air crew to cosmic radiation where it may be a source of significant radiation doses, particularly in the case of pregnant female crew. This paper will look in detail at the requirements of the Directive as they pertain to air crew and will set out the methods by which Member States of the European Union will be required to implement the Directive when it becomes legally binding in the year 2000.
Perspectives of Those Impacted:
Flight Attendant’s Perspective,
Emily Carter,
Association of Professional Flight Attendants
Airline Pilot’s Perspective, Gary Butler
An Airline’s Perspective, Michael Bagshaw,
British Airways
Panel Discussion
Robert Barish, Chairman
Michael Bagshaw
Gary Butler
Emily Carter
Wallace Friedberg
Ian R. McAuley
Warren K. Sinclair
Summary of Presentations
Exposure to Cosmic Radiation–Where Do We Go from Here?
Roger Clarke,
National Radiological Protection Board, United Kingdom
The Program Committee
Lawrence W. Townsend, Chairman
Robert J. Barish
R.J. Michael Fry
Ian R. McAulay
Jerome S. Puskin
Walter Schimmerling
Martha Waters
John W. Wilson
News & Events