Biological effects of cosmic radiation.
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Animals↗
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Genetic and physiological damage induced by cosmic radiation on dry plant seeds during space flight.
Total evaluation of cosmic radiation effect with or without discrimination of individualized HZE-ion effects in dry Arabidopsis seeds flown for 10 days on STS-9, yielded significant evidence for radiation damage in space. They depend on the biological criteria tested (seed germination, morphogenesis, embryo lethality, mutation rate) which stand for early, physiological and late genetic effects. They are also related to the radiation shielding environment in the space shuttle. Proceeding from these results three direct questions can be posed for present (LDEF-1) and future (ERA-1, D-2) experiments in space: What is the influence of cosmic radiation on cytogenetic repair and ontogenetic restitution processes? Does microgravity disorder the morphogenesis (i.e. growth and cell differentiation)? Is there an interaction between the effects of cosmic radiation and microgravity in eukaryotic plant systems?
Arabidopsis↗
British Airways measurement of cosmic radiation exposure on Concorde supersonic transport.
The galactic cosmic radiation field at aircraft operating altitudes is complex, with a large energy range and the presence of all particle types. The calculation of the complex radiation fields is difficult, as is the measurement. British Airways continues to cooperate with the U.K. National Radiological Protection Board in measuring cosmic radiation doses on supersonic and subsonic aircraft using a range of devices.
Aircraft↗
Cosmic radiation and evolution of life on earth: roles of environment, adaptation and selection.
The role of ionizing radiation in general, and cosmic radiation in particular, in the evolution of organisms on the earth by adaptation and natural selection is considered in a series of questions: (1) Are there times during the evolution of the earth and of life when genetic material could be exposed to heavy ion radiation? (2) Throughout the course of chemical and biological evolution on the earth, what fraction of environmental mutagenesis could be attributable to cosmic and/or solar ionizing radiation? (3) Is ionizing radiation an agent of adaptation or selection, or both? (4) What can the cladistics of the evolution of genetic repair tell us about the global history of genotoxic selection pressures? (5) How much genetic diversity can be attributed to the selection of radiation-damage repair processes?
Animals↗
Estimated individual annual cosmic radiation doses for flight crews.
INTRODUCTION: Individual annual cosmic radiation doses for fulltime airline crewmembers were calculated for 12 consecutive months using data from flight profiles and previously reported cosmic radiation intensity measurements at various altitudes. METHODS: Every flight of each crewmember was analyzed using block time and aircraft flight profiles. Actual flight time at various flight levels was first calculated, then cumulative total body radiation doses were calculated for each flight phase and altitude. RESULTS: Cabin crewmembers averaged 673 block hours (range 906-273 h) and pilots 568 block hours (range 833-168 h). Average annual cosmic ray dose for cabin crews was 2.27 mSv x a(-1) (range between 3.1 - 0.72 mSv x a(-1)). Long-distance MD11 flight captains received the highest annual doses of 2.19 mSv x a(-1) (2.83 - 1.08 mSv x a(-1)). M.D.80 pilots who also fly long high-altitude sectors in Europe received 1.94 mSv x a(-1) (2.37 - 1.12) and other aircraft type cockpit crews averaged between 1.49 - 1.26 mSv x a(-1). CONCLUSION: The calculated individual doses reflect the type of aircraft flown and the amount of flight time. The calculated doses are lower than those received by simply assuming constant radiation exposure at all altitudes during flight. Annual individual doses are well below the maximum 5 mSv x a(-1) allowed by the national laws.
Aircraft↗
[A simple method for estimating cosmic radiation effective dose rate].
OBJECTIVE: To study a simple method for estimating cosmic radiation effective dose rate for aircrew. METHOD: Using a new program by written in Object Pascal language on PC in Windows operation system on the basis of an algorithm designed in this paper, cosmic radiation effective dose rates at various altitudes and latitudes were calculated and compared with those obtained by using CARI-6 and FLUKA. RESULT: The calculated results by using the simple method agree remarkably with those calculated by using CARI-6 and FLUKA, in three groups of data compared with CARI-6, differences are within 25% for 76%, 71% and 100% of the data respectively; in the group of data compared with FLUKA, differences are all within 20%. CONCLUSION: The simple method is applicable in estimating cosmic radiation effective dose rate for flight altitude of 7000 to 20,000 m.
Aircraft↗
Characteristics of biological effects of cosmic radiation, model investigations.
In view of the probability of the influence of ionizing radiation on crewmen and the appropriate problem of creating adequate anti-radiation protection, it is necessary to investigate the peculiarities of biological effects of cosmic radiation. Under actual space flight conditions, cosmic radiation will affect the human organism in the complex along with other factors. Full imitation of cosmic radiation on the ground is impossible but it can exert influence on the human radiosensibilty. In this connection, the successful solution of the problem of obtaining appropriate information can be made by a reasonable combination of both ground radiobiological and medical-hygienic investigations and those carried out by using artificial earth satellites. The available experience in carrying out such research and its results are given in this report. Information on investigating the peculiarities of biological effects of protons in the wide spectrum of energy is also included. The report contains the data of observing immediate and later effects of radiation influence on higher animals and also on many biological objects arranged in various levels of evolution and biological organizations. The values of the RBE for protons are given.
Amniotic Fluid↗
Cosmic radiation and magnetic field exposure to airline flight crews.
BACKGROUND: Flight crews are exposed to elevated levels of cosmic radiation and to magnetic fields generated by the aircraft's electrical system. The purpose of this study was to quantify these two occupational exposures. METHODS: Magnetic fields were measured during 37 flights (23 in the cockpit and 14 in the cabin) using an Emdex Lite personal dosimeter. All cockpit measurements were taken on the B737/200. Cabin measurements were taken in several aircraft types, including the B737, B757, DC9, and L1011. Cosmic radiation was computer estimated for 206 flights using the Federal Aviation Administration's program CARI-3C. RESULTS: Magnetic field levels in the cockpit had a mean value of approximately 17 milliGauss (mG), while cabin measurements were lower (mean values of approximately 3 or less in economy, 6 in first class, 8 in front serving areas). Cosmic radiation equivalent dose rates to bone marrow and skeletal tissue ranged from 0.3 to 5.7 microsieverts per hour. CONCLUSIONS: Elevated magnetic field levels in front serving areas and the cockpit suggest the need for further study to evaluate long-term exposure to flight crew members who work in these areas. Cosmic radiation levels are well below occupational limits for adults, but may require some pregnant flight crew members to adjust their flying time or routes.
Aerospace Medicine↗
Evaluation of exposure to cosmic radiation of flight crews of Lithuanian airlines.
BACKGROUND: In Lithuania the average annual effective dose due to cosmic radiation at the sea level is 0.38 mSv. The dose rate caused by cosmic radiation increases with altitude due to the decrease in attenuation of cosmic radiation by atmosphere. Dose rates at altitudes of commercial flights are tens times higher than those at the sea level. For this reason people who frequently fly receive higher doses which might even be subject to legal regulations. The European Council Directive (96/29/Euratom) on basic radiation safety standards requires that doses of aircrews members be assessed and the appropriate measures taken, depending on the assessment results. OBJECTIVES: The aim of this study was to evaluate potential doses, which can be received by members of aircrews of Lithuanian Airlines. The assessment was done by performing measurements and calculations. METHODS: Measurements were performed in flying aircrafts by thermoluminescent detectors, Geiger Muller counters and neutron rem counter. Such an approach lead to evaluation of doses due to directly ionizing particles and neutrons. Calculations were done with the help of the code CARI-6M. Such parameters as flight route, solar activity, duration and altitudes of flight were taken into account. Doses received during different flights and in different aircrafts were assessed. The results of measurements and calculations were compared and differences discussed. The results were also compared with the data obtained in other similar studies. RESULTS: It was found that the highest doses are received in flights to Paris, London, Amsterdam, and Frankfurt by aircraft B737. A number of flights causing annual doses higher than 1 mSv was estimated. CONCLUSIONS: Despite the fact that only European flights are operated by Lithuanian Airlines the dose of 1 mSv may be exceeded under some circumstances. If it happens some radiation protection measures shall be taken. These measures are also discussed.
Aerospace Medicine↗
Exposure of airline pilots and cabin crew to cosmic radiation during flight--what's the fuss?
The International Commission on Radiological Protection (ICRP) had in 1990 recommended that civilian aircrew be classified as being occupationally exposed to low-dose ionizing radiation, in view of their increased exposure to cosmic rays at altitude. In 2000, the European Union had gone ahead with legislation which requires all European airlines to monitor cosmic radiation levels during flight and to inform aircrew of the possible health risks. However, the evidence for a causal link between cosmic radiation exposure and health risks remains elusive despite recent findings of increased cancer incidence among airline pilots and cabin crew. The inconclusiveness of the evidence notwithstanding, there are compelling reasons for adopting a prudent and precautionary stance.
Aerospace Medicine↗
Dosimetry for occupational exposure to cosmic radiation.
In the course of their work, aircraft crew and frequent flyers are exposed to elevated levels of cosmic radiation of galactic and solar origin and secondary radiation produced in the atmosphere, aircraft structure, etc. This has been recognised for some time and estimates of the exposure of aircraft crew have been made previously and included in, for example, UNSCEAR (United Nations Scientific Committee on the Effects of Atomic Radiation) publications. The recent increased interest has been brought about by several factors--the consideration that the relative biological effectiveness of the neutron component as being underestimated; the trend towards higher cruising altitudes for subsonic commercial aircraft and business jet aircraft; and, most importantly, the recommendations of the International Commission on Radiological Protection (ICRP) in Publication 60, and the revision of the Euratom Basic Safety Standards Directive (BSS). In 1992, the European Dosimetry Group (EURADOS) established a Working Group to consider the exposure to cosmic radiation of aircraft crew, and the scientific and technical problems associated with radiation protection dosimetry for this occupational group. The Working Group was composed of fifteen scientists (plus a corresponding member) involved in this field of study and with knowledge of radiation measurement at aviation altitudes. This paper is based on the findings of this Working Group. Where arrangements are made to take account of the exposure of aircraft crew to cosmic radiation, dose estimation procedures will not be necessary for persons for whom total annual doses are not liable to exceed 1 mSv, and therefore, in general, for crew on aircraft not routinely flying above 8 km. Where estimates of effective dose and, in the case of female staff who are pregnant, equivalent dose to the embryo or fetus, are required (for regulatory or other purposes), it was concluded that the preferred procedure was to determine route doses and fold these with data on staff rostering.
Aircraft↗
Assessing exposure to cosmic radiation during long-haul flights.
The assessment of exposure to cosmic radiation on board aircraft is one of the concerns of organizations responsible for radiation protection. Cosmic-particle flux increases with altitude and latitude and depends on solar activity. To illustrate the effect of these parameters, exposure has been estimated on several airlines operating subsonic and supersonic aircraft on transatlantic, Siberian and transequatorial routes. Measurements have been made with a tissue-equivalent proportional counter using the microdosimetric technique. This type of system provides the absorbed dose, the ambient dose equivalent, the mean quality factor, and the dose distribution as a function of lineal energy. Data were collected at maximum solar activity in 1991-1992 and at minimum activity in 1996-1998. The lowest mean dose rate measured was 3 microSv h(-1) during a Paris-Buenos Aires flight in 1991. The highest rates were 6.6 microSv h(-1) during a Paris-Tokyo flight on a Siberian route and 9.7 microSv h(-1) on Concorde in 1996-1997. The mean quality factor is around 1.8. The corresponding annual effective dose, based on 700 h of flight for subsonic aircraft and 300 h for Concorde, can be estimated at between 2 mSv for the least-exposed routes and 5 mSv for the more-exposed routes.
Aviation↗
Regulatory control of air crew exposure to cosmic radiation: the European approach.
The current European Directive on radiation protection requires that exposure of air crew to cosmic radiation should be assessed if it is likely to exceed 1 milliSievert per year. The approach to this problem in the European Union is described and the relative merits of experimental measurement and computer based assessment are discussed. The particular importance of protection against cosmic radiation exposure in the case of female air crew during pregnancy is described.
Aircraft↗
Linear energy transfer spectra of cosmic radiation aboard the Cosmos-1129 satellite.
The most important characteristic of the hazard due to cosmic radiation is the spectrum of linear energy transfer (LET), which enables one to estimate the dose equivalent. This has prompted us to study LET spectra of cosmic radiation aboard Cosmos-1129 using nuclear emulsions as a threshold detector.
Alpha Particles↗
Determination of dose distribution of cosmic radiation behind different shielding thicknesses.
Investigations are described for the determination of dose distributions of cosmic radiation behind different shielding thicknesses. For this purpose, ultra-thin thermoluminescent detectors on a base of CaF2-polytetrafluorethylene (PTFE) were prepared and arranged in a stack at the outer wall of the biosatellite Cosmos 1887. During the 13 days of flight in a near-Earth orbit, the detectors were exposed to the unshielded cosmic radiation. After the flight, the dose distribution in the stack was determined by successive evaluations of the CaF2-PTFE discs. In the upper layers of the detector arrangement, dose values up to 100 Gy were observed. The strong decrease of the dose within a few mm demonstrates that weak particle radiation is dominant in the radiation field under investigation.
Calcium Fluoride↗
[Estimates of the statistical characteristics of solar flares of cosmic radiation in the 20th and 21st cycles of solar activity].
This paper presents the principal characteristics of solar cosmic radiation events in the 20th and 21st cycles of solar activity. A uniform row of data concerning solar cosmic radiation has been obtained. An analysis of large-scale variations of the proton intensity time profile has demonstrated that the variations are associated with the structure of the interplanetary magnetic field which depends on interplanetary shock waves. The relative "proton" geoeffectiveness of the Sun southern hemisphere is significantly lower than of the northern hemisphere in both the 20th and the 21st cycles. Empirical distributions of standard characteristics of the SCR proton intensity profile and regression relations have been derived. They can be used to predict radiation parameters of SCR events.
Cosmic Radiation↗
Cytogenetic analysis in human lymphocytes after exposure to simulated cosmic radiation which reflects the inflight radiation environment.
PURPOSE: To determine the relative biological effectiveness (RBE) of a mixed neutron-gamma-radiation field and its high LET component on the induction of chromosome aberrations in human lymphocytes. MATERIALS AND METHODS: Human lymphocyte cultures were exposed in vitro to low doses of simulated cosmic radiation (2.39-5.81 mGy) at low dose rates (0.04-0.15 mGy/h). Chromosome aberrations, micronuclei, and sister chromatid exchanges (SCE) were analysed. The RBE for dicentric chromosomes was given in comparison to 60Co gamma-rays. RESULTS: For the induction of dicentric chromosomes by simulated cosmic radiation the RBE was up to 64, and up to 113 when calculating only the high LET component. The investigation of micronuclei and SCE showed no significant differences between controls and irradiated samples. CONCLUSIONS: Preliminary data indicate a high biological effectiveness of cosmic radiation and its neutron component in comparison with 60Co gamma-radiation.
Aerospace Medicine↗
Influence of cosmic radiation and/or microgravity on development of Carausius morosus.
Eggs of Carausius morosus were exposed to spaceflight conditions in two spaceflight missions, the German 7 day Spacelab Mission D1 and the Soviet 12.56 day Biosatellite Mission "COSMOS 1887". During spaceflight the eggs continued their development. Eggs of five different ages representing different sensitivity to radiation and different capacity to regeneration were used to investigate the influence of cosmic radiation and/or microgravity on insect development. Using the Biostack concept--eggs in monolayers sandwiched between nuclear track detectors--and the 1 g reference centrifuge of BIORACK in D1 we were able to separate effects of heavy ions of the cosmic radiation from microgravity effects and also from combined effects of these two factors in space. After retrieval, hatching rates, embryonic and larval growth kinetics and anomaly frequencies were determined. Microgravity leads to a reduced hatching rate of eggs exposed in the early stages of development. Hatching was normal in eggs which were exposed on the 1 g reference centrifuge. Hits by heavy ions caused body anomalies. The combined action of heavy ions and microgravity resulted in an unexpectedly high frequency of anomalies. These results obtained from the Spacelab Mission D1, were confirmed in an experiment onboard of COSMOS 1887. In addition to the previous analysis, embryonic development before hatching was followed which showed no major difference between flight and the ground control specimens. Since a reconfirmation of reduced hatching rates was observed in COSMOS 1887, too, the above results suggest some microgravity induced functional impairment of the hatching activity, rather than blockage in embryonic development.
Abnormalities, Radiation-Induced↗