Showing papers in "Health Physics in 1983"
TL;DR: Uranium is found in ground and surface waters due to its natural occurrence as discussed by the authors, and its presence is due to human activities such as mining and milling uranium, thus it is also found in drinking water.
Abstract: Uranium is found in ground and surface waters due to its natural occurrence. In some cases, its presence is due to human activities such as mining and milling uranium. Thus, it is also found in drinking water. The range of concentrations existing in drinking water supplies in the U.S. is tab
180 citations
TL;DR: This paper summarizes the results of the background measurements made as part of the ORNL program of radiological surveillance at inactive uranium mills and sites formerly utilized during Manhattan Engineer District and early Atomic Energy Commission projects, and provides a brief analysis of regional differences and similarities in data values.
Abstract: Background radionuclide concentrations in surface soil across the U.S. have been measured by the Remedial Action Survey and Certification Activities Group of the Health and Safety Research Division at Oak Ridge National Laboratory (ORNL). These measurements have been made as part of the ORNL
169 citations
TL;DR: Indoor atmospheric radon concentrations are found to vary with time of day, geographic location and story above ground, and it is estimated that the mean value for normal areas of the contiguous United States lies in the range of 100-400 pCi/m3 and is probably about 250 pCis3.
Abstract: The sources of outdoor and indoor atmospheric radon are examined. The variation of outdoor atmospheric radon with time of day, time of year, altitude and geographic location is quantitatively assessed. Average values of outdoor atmospheric radon concentrations are examined and it is estimate
142 citations
TL;DR: The theory of radon adsorption from air by a charcoal bed is developed, giving numerical estimates at all stages, and simple methods for determining the diffusion constant for the charcoal being used, and for optimizing the depth of the charcoal bed, are presented.
Abstract: Because of interest in charcoal adsorption as an inexpensive radon monitoring technique that may be suitable for mass data collection, the theory of radon adsorption from air by a charcoal bed is developed, giving numerical estimates at all stages. The method is practical down to air concent
103 citations
TL;DR: In damage tests conducted on rabbit and monkey eyes, the threshold values for retinal damage resulting from different laser radiation were determined and probit analysis showed a very precise determination of the thresholdvalues based on ophthalmoscopical visibility.
Abstract: In damage tests conducted on rabbit and monkey eyes, the threshold values for retinal damage resulting from different laser radiation were determined. The reproduction of the “worst-case” situation was ensured by the test apparatus. All physical parameters, such as power/energy, exposure tim
99 citations
TL;DR: Average 222Rn levels in domestic water supplies for each of the 16 counties were found to be significantly correlated with rates for all cancers combined and rates for lung and reproductive cancers in the counties, although numerous factors other than cancer induction by indoor daughter exposures may be responsible for the observed correlations.
Abstract: The distribution of 222Rn has been measured in the sixteen counties of Maine, U.S.A. by liquid scintillation counting of water samples from more than two thousand public and private wells. Three hundred and fifty of these wells have been characterized for geology and hydrology. Airborne radon has been measured in seventy houses with grab samples and in eighteen houses for 5-7 days each with continuously recording diffusion-electrostatic radon detectors. Concentrations of radon in water ranged from 20 to 180,000 pCi/l. Granite areas yielded the highest average levels (mean = 22,100 pCi/l.; n = 136), with considerable intra-granite variation. Metasedimentary rocks yielded levels characteristic of the lithology for metamorphic grades ranging from chlorite to andalusite. Sillimanite and higher-grade rocks yielded higher 222Rn levels, probably due to the intrusion of uranium-bearing pegmatites in these terranes. Airborne 222Rn in homes ranged from 0.05 to 210 pCi/l. At the high end of this range, doses will exceed recommended industrial limits. In some homes only a small fraction of the airborne 222Rn was due to the water supply. Average 222Rn levels in domestic water supplies for each of the 16 counties, calculated by areally averaging rock types and their associated 222Rn levels, were found to be significantly correlated with rates for all cancers combined and rates for lung and reproductive cancers in the counties. Although numerous factors other than cancer induction by indoor daughter exposures may be responsible for the observed correlations, these have not been investigated in detail.
98 citations
TL;DR: A series of nomograms that simplify determination of diagnostic X-ray shielding requirements with lead are presented, eliminating the over-shielding inherent in the "add one HVL" approximation and allowing a variety of more cost effective materials to be considered for secondary barriers.
Abstract: A series of nomograms that simplify determination of diagnostic X-ray shielding requirements with lead are presented. All recommendations of the NCRP, except that to "add one half value layer" in determining secondary barriers, were followed in the production of these curves. For secondary barriers, the shielding required to reduce the weekly exposure to the applicable MPD has been determined. This eliminates the over-shielding inherent in the "add one HVL" approximation and allows a variety of more cost effective materials to be considered for secondary barriers.
96 citations
TL;DR: The results of this survey suggest that concrete and other building materials commonly used in the U.S. are not the primary source of radon in typical U.s. houses.
Abstract: Building materials commonly used in the U.S. were surveyed for both radionuclide content and radon emanation rate. Particular emphasis was placed on concrete, for which samples from ten major metropolitan areas were measured. Gamma-ray spectroscopy techniques, as well as direct radon emanation measurements, were employed in this study. The results of this survey suggest that these materials are not the primary source of radon in typical U.S. houses.
75 citations
TL;DR: The length of time that a therapeutically useful amount of DTPA is retained in the body is approximately twice that following intravenous injection.
Abstract: This study in human volunteers was designed to compare the retention of diethylenetriaminepentaacetic acid (DTPA) in the body after intravenous (i.v.) injection with that following inhalation by using a 14C labelled tracer. After i.v. injection retention in the blood could be described by three exponential components with half-times of about 1.4 min (approximately 60%) 14.3 min (approximately 20%) and 95 min (approximately 20%). By 24 hr more than 99% of the 14C-DTPA had been excreted in the urine and less than 0.5% remained in the plasma. After inhalation of 14C-DTPA retention in the lungs could be represented by a single component with a half time of about 75 min. As a consequence the length of time that a therapeutically useful amount of DTPA is retained in the body is approximately twice that following intravenous injection.
73 citations
TL;DR: In this article, the authors examined the variability of the environmental half-time (Tw) measured in the literature for various radionuclides and methods of deposition and found that the variability is related in part to the physicochemical form of the depositing substance, vegetation type and growth form, climate, season and experimental procedure.
Abstract: After radionuclides are deposited on vegetation, environmental removal processes combine with radioactive decay to reduce the quantity of initial contamination. The time in which one-half of the radioactivity is removed from vegetation by environmental processes alone is referred to as the environmental half-time, Tw. For long-lived radionuclides, the dose to man via ingestion of contaminated terrestrial foods may be directly influenced by values of Tw, provided that environmental removal processes dominate root uptake and time is sufficiently long between initial exposure of vegetation and harvest. Values of Tw reported in the literature for various radionuclides and methods of deposition are examined. Factors affecting the variability of Tw are related in part to the physicochemical form of the depositing substance, vegetation type and growth form, climate, season, and experimental procedure. For growing vegetation, values of Tw are generally lower than those reported for dormant vegetation. Values of Tw for iodine vapor and iodine particulate are less than values of Tw reported for particulates of other elements. Values of Tw determined on a per unit vegetation mass basis are also less than values of Tw determined on a per unit ground area basis, the differences being attributable to the effects of growth dilution. Although an assessor has a range from which to select a value of Tw for the purpose of estimating contamination by long-lived radionuclides, the variability in Tw is small in comparison to many other parameters used in environmental radiological assessments.
68 citations
TL;DR: In vitro solubility tests were useful, simple and easily applied to individual materials potentially inhaled by humans and suggested the dominant role of mechanical processes in PuO2 clearance from the lung.
Abstract: Dissolution characteristics of mixed-oxide nuclear fuels are important considerations for prediction of biological behavior of inhaled particles. Four representative industrial mixed-oxide powders were obtained from fuel fabrication enclosures. Studies of the dissolution of Pu, Am and U from aerosol particles of these materials in a serum simulant solution and in 0.1M HCl showed: (1) dissolution occurred at a rapid rate initially and slowed at longer times, (2) greater percentages of U dissolved than Pu or Am: with the dissolution rates of U and Pu generally reflecting the physical nature of the UO2-PuO2 matrix, (3) the temperature history of industrial mixed-oxides could not be reliably related to Pu dissolution except for a 3-5% increase when incorporated into a solid solution by sintering at 1750 degrees C, and (4) dissolution in the serum simulant agreed with the in vivo UO2 dissolution rate and suggested the dominant role of mechanical processes in PuO2 clearance from the lung. The rapid initial dissolution rate was shown to be related, in part, to an altered surface layer. The advantages and uses of in vitro solubility data for estimation of biological behavior of inhaled industrial mixed oxides, such as assessing the use of chelation therapy and interpretation of urinary excretion data, are discussed. It was concluded that in vitro solubility tests were useful, simple and easily applied to individual materials potentially inhaled by humans.
TL;DR: In this article, the authors derived effective dose-rate factors for external exposure to photons and electrons using the revised DOSFACTER computer code (Ko81a) for three exposure modes, i.e., immersion in contaminated air and water, and irradiation at a height of 1 m above a contaminated ground surface.
Abstract: Dose-rate conversion factors for external exposure to photons and electrons have been calculated for approx. 500 radionuclides of potential importance in environmental radiological assessments. The three exposure modes considered are immersion in contaminated air, immersion in contaminated water, and irradiation at a height of 1 m above a contaminated ground surface. For each exposure mode, the source region is assumed to be effectively semi-infinite or infinite in extent with uniform radionuclide concentration. The dose-rate factors then give external dose-equivalent rates per unit radionuclide concentration in air, in water or on the ground surface. The results are tabulated in this paper in the form of effective dose-rate factors based on the definition of the effective dose equivalent given in ICRP Publication 26 (ICRP77). The effective dose-rate factors are obtained from photon dose-rate factors for 23 separate body organs and electron dose-rate factors for skin calculated with the revised DOSFACTER computer code (Ko81a). In addition to presenting the dose-rate factor equations and the tabulated results, this paper emphasizes the assumptions underlying the calculations for each exposure mode, differences between the organ dose-rate factors for photons used here and those used previously with the original version of the DOSFACTER code (Ko80a), and limitations inherent in application of the idealized external dose-rate factors to realistic environmental radiological assessments.
TL;DR: A study of gardens contaminated by uranium processing wastes was carried out in the town of Port Hope, Ontario, during the summer of 1976 as discussed by the authors, where concentrations of 226Ra, 210Pb, and total uranium were measured in soils and in garden produce.
Abstract: A study of gardens contaminated by uranium processing wastes was carried out in the town of Port Hope, Ontario, during the summer of 1976. Concentrations of 226Ra, 210Pb, and total uranium were measured in soils and in garden produce. Highest concentrations were found in root and stem vegetables and, for radium, also in leafy vegetables. Fruit generally showed the lowest values. Uptake was consistent with a linear dependence on soil concentration. Mean concentration factors of 1.1 X 10(-3), 0.37 X 10(-3), and 0.075 X 10(-3) were obtained for 226Ra, 210Pb, and uranium, respectively. The highest estimated dose to an individual who ingested produce from a contaminated garden was 68 mrem/yr to bone surface from 226Ra. The implications of these findings for other communities affected by nuclear fuel-cycle operations are discussed.
TL;DR: Dose calculations suggest that fly ash will contribute to a reduction in effective dose equivalent due to the reduced radon-exhalation rate in concrete containing fly ash.
Abstract: The radiological consequences of using fly ash as a component of cement are discussed. Measurements of the activity concentrations of the fly ash and cement are reported together with measurements of emanation coefficients and exhalation rates. The radon-exhalation rate was found to be signi
TL;DR: Measurements of radon, radon daughters and air exchange rates have been carried out in 225 dwellings in Sweden and the F-factors have been compared with the theoretical model described by Wicke, taking into account the wall effect.
Abstract: Consideration of the equilibrium factor F between the concentration of the radon daughters and the concentration of radon is a part of the evaluation of the measurements of radon daughter concentrations in dwellings when applying limits. Measurements of radon, radon daughters and air exchange rates have been carried out in 225 dwellings in Sweden. The F-factors have been compared with the theoretical model described by Wicke, taking into account the wall effect. The parameters of the model are discussed. The situation of the dwelling and the habits of the occupants can be expected to have the greatest importance for the F-factors although the ventilation rate is usually the most important modifying factor. For low air exchange rates (l less than 0.30 hr-1) the probability that the F-factors were between 0.28 and 0.74 was 95% calculated according to the t-distribution. The arithmetical mean was found to be 0.51. For air exchange rates close to the average rate (0.30 less than l less than 0.60 hr-1), the F-factors were between 0.21 and 0.66 with a mean of 0.43, and for high air exchange rates (l greater than 0.60 hr-1) the F-factors were between 0.21 and 0.47 with a mean value of 0.33.
TL;DR: The function I = (C + ..beta..D/sup 2/)e/sup -..gamma ..D/ was used to predict the number of bonemore sarcomas in all other pre-1950 radium cases (medical, laboratory, and other exposure); fewer were actually observed than the fit of this function to the female dial workers predicted.
Abstract: The incidence of bone sarcomas among 3055 female radium-dial workers who entered the dial industry before 1950 was used to determine dose-response relationships for the induction of bone sarcomas by radium. Two subpopulations were analyzed: all measured cases who survived at last five years after the start of employment and all cases who survived at least two years after first measurement. The first constituted a group based on year of entry; it contained 1468 women who experienced 42 bone sarcomas; the expected number was 0.4. The second comprised a group based on first measurement; it contained 1257 women who experienced 13 bone sarcomas; the expected number was 0.2. The dose-response function, I = (C + ..cap alpha..D + ..beta..D/sup 2/)e/sup -..gamma..D/, and simplifications of this general form, were fit to each data set. Two functions, I = (C + ..cap alpha..D + ..beta..D/sup 2/)e/sup -..gamma..D/ and I = (C + ..beta..D/sup 2/)e/sup -..gamma..D/, fit the data for year of entry (p greater than or equal to 0.05); both these functions and I = (C + ..cap alpha..D) fit the data for first measurement. The function I = (C + ..beta..D/sup 2/)e/sup -..gamma..D/ was used to predict the number of bonemore » sarcomas in all other pre-1950 radium cases (medical, laboratory, and other exposure); fewer were actually observed than the fit of this function to the female dial workers predicted.« less
TL;DR: It appears that the major cause of the observed differences in222Rn concentration is variation from one house to another in the rate at which 222Rn enters houses from its sources.
Abstract: To elucidate any connection between high radon concentrations and low-infiltration houses, we have concurrently measured the 222Rn concentration and the infiltration rate in U.S. houses. Three housing surveys have been undertaken: one in "energy-efficient" houses located throughout the U.S. and two in "conventional" houses in the San Francisco area and in Maryland. In each of the groups surveyed, no clear correlation was observed between 222Rn concentrations and infiltration rate, although each parameter varied over a wide range. Infiltration rates for the entire sample, numbering 98 houses, ranged between 0.02 and 1.6 air changes per hr, and 222Rn concentrations ranged from 0.1 to 27 pCi/l. It appears that the major cause of the observed differences in 222Rn concentration is variation from one house to another in the rate at which 222Rn enters houses from its sources.
TL;DR: The phosphor Li2B4O7: Cu (0.03% by weight) has an effective atomic number of 7.3, which is very similar to that of tissue, which suggests that the phosphor should have excellent properties for thermoluminescent dosimetry.
Abstract: The phosphor Li2B4O7: Cu (0.03% by weight) has an effective atomic number of 7.3, which is very similar to that of tissue (7.4). This suggests that the phosphor should have excellent properties for thermoluminescent dosimetry. The phosphor prepared by a sintering method shows two glow peaks composed of a dosimetric peak at 205 degrees C and a shoulder at 120 degrees C, and a broad emission band peaking at 368 nm. The material based on the stoichiometric compound of Li2O . 2B2O3 has a good moisture resistant property. The dosimetric characteristics are as follows: (1) The sensitivity of gamma rays is about 20 times higher than that of Li2B4O2: Mn prepared by the conventional melting method. (2) The dosimetry peak of 205 degrees C fades less than 9% in intensity at 25 degrees C after 60 days in dark. (3) The TL output is linear with exposure to about 10(5) R, becoming sublinear above it. (4) The sensitivity loss caused by humidity is about 10-25% after 2-6 months of storage in air of 90% relative humidity at 25 degrees C. (5) The energy dependence of TL output for photons is flat within the limit of 10% from 40 keV to 7 MeV. (6) The light induced fading is 10% after 3 h room lighting at 1000 lux.
TL;DR: Increased repair capability for DNA lesions inflicted by a second insult after protracted low-dose irradiation after in vitro UV irradiation is indicated.
Abstract: Unscheduled DNA synthesis induced by in vitro UV irradiation was investigated in lymphocytes of persons occupationally exposed to low doses of ionizing radiation (maximum registered radiation dose: 98 mrad/month). For radiation exposures greater than 14 mrad/month above background level, increased rates of UDS after in vitro UV irradiation of lymphocytes were found. The bromodeoxyuridine differential chromatid labeling technique was applied to the examination of spontaneous and Mitomycin C (MMC)-induced sister chromatid exchanges (SCE) in the same population. No statistically significant difference could be determined in spontaneously occurring SCEs, while MMC induced SCEs were significantly reduced in persons exposed to radiation doses greater than 14 mrad/month, thus indicating increased repair capability for DNA lesions inflicted by a second insult after protracted low-dose irradiation.
TL;DR: It is demonstrated that the initial part of the activity growth curve determines the total free exhalation rate of the sample used, independently of container leakage and back diffusion.
Abstract: The exhalation of radon from porous materials like mining wastes and building materials can be determined by studying the growth of radon activity in vessels containing samples of the materials. It is demonstrated that the initial part of the activity growth curve determines the total free exhalation rate of the sample used, independently of container leakage and back diffusion. It is furthermore shown that a specific area exhalation rate adequately describes the exhalation process, when the exhalation is restricted to take place in one direction only, and when the dimension in the exhaling direction is greater than approx. 2 times the diffusion length. A determination of the free surface exhalation rate as a function of the sample thickness also yields information on the diffusion length, as well as the radon production rate per unit volume of material. In case of sample dimensions smaller than about half the diffusion length, the total exhalation rate is shown to be proportional to the mass or volume of the sample.
TL;DR: The indoor environment is successfully described by the model and that plate-out of radon decay products on surfaces is much less than previous work has suggested, and the model provides a plausible explanation of the effectiveness of a variety of techniques that remove radon Decay products from the air.
Abstract: Where it is not feasible to reduce radon levels in houses, exposure to radon decay products may still be reduced through air filtration or other air treatment techniques. A model which accurately describes the behavior of decay products indoors would be helpful to development or improvement of such air treatment techniques. We use a minor modification of a well-known model to describe the behavior and fate of radon decay products in the average indoor environment, and examine the adequacy of the model to predict the impact of a variety of air treatment techniques on indoor radon decay product levels. We find that the indoor environment is successfully described by the model and that plate-out of radon decay products on surfaces is much less than previous work has suggested. We also find that the model provides a plausible explanation of the effectiveness of a variety of techniques that remove radon decay products from the air.
TL;DR: The objectives of this study were to compare the effects of technetium and uranium on the yield and uptake, and to identify the organ of accumulation, of an edible leafy vegetable growing in sandy and peaty soils.
Abstract: The objectives of this study were to compare the effects of technetium and uranium on the yield and uptake, and to identify the organ of accumulation, of an edible leafy vegetable growing in sandy and peaty soils. In sand, where the soil's sorption capacity is negligible, technetium uptake is four orders of magnitude higher than from peat, suggesting no plant mediation of uptake and thus a constant concentration factor (greater than 50) in an oxidizing environment where technetium is continuously supplied. The technetium is predominantly translocated to the shoots. When soil fixation occurs, as in peat, this becomes the controlling factor in the plant uptake of technetium. In the case of uranium, plant mediation is more significant. Uranium uptake by Swiss chard is up to 80 times higher from sand than from peat. The uranium is restricted to the root system and may only be precipitated on the outer root membrane and may not accumulate in the roots.
TL;DR: In this paper, the present level of plutonium in human tissues of people in the F.R.G., due solely to fallout from weapons testing, 30 sets of tissues and bones from Munich residents were obtained at autopsy.
Abstract: To determine the present level of plutonium in human tissues of people in the F.R.G., due solely to fallout from weapons testing, 30 sets of tissues and bones from Munich residents were obtained at autopsy. Each set of tissues consisted of the entire lung, the entire liver, 300 g vertebrae, 300 g ribs and the lymph nodes. All subjects were males, born before 1940. Wet ashing, followed by solvent extraction, electrodeposition, and alpha-spectrometry were used to isolate and quantitate the plutonium isotopes present. The median concentrations of 239/240Pu (in fCi/kg wet weight) observed were: livers (530), vertebrae (92), ribs (73), lymph nodes (58) and lungs (28). The ratio of 238Pu/239/240Pu (in %) was livers 3.5, lungs 5.6, ribs 4.0 and vertebrae 3.2. Age trends for the plutonium concentration in livers, lungs, vertebrae and ribs were not observable. Possible correlations between the plutonium concentrations in livers, lungs and bones are discussed. The results are in many respects similar to observations in the U.S.A. and Southern Finland.
TL;DR: In this paper, the intensity of the magnetic field and the frequency spectrum of the emissions at extremely low frequencies (ELF) (5-500 Hz) were measured for a few VDTs and compared with the background field intensities and emissions from other devices.
Abstract: Video display terminals (VDTs) are in widespread use and can be found in practically every modern office. Assessment of possible health effects of electromagnetic emissions from these devices is necessary. The intensity of the magnetic field and the frequency spectrum of the emissions at extremely low frequencies (ELF) (5-500 Hz) were measured for a few VDTs and compared with the background field intensities and emissions from other devices. The emissions in the frequency range investigated are of such low intensities that they are very unlikely to have any biological effects, let alone represent a health hazard.
TL;DR: Fish from lakes affected by an operating uranium mine and mill had radionuclide levels one to two orders of magnitude above levels in fish from an uncontaminated control lake, but did not vary with fish sex or age.
Abstract: Radionuclide levels in fish from the Beaverlodge Lake area, Saskatchewan, Canada, varied significantly among lakes, species and tissues, but did not vary with fish sex or age. Fish from lakes affected by an operating uranium mine and mill had radionuclide levels one to two orders of magnitude above levels in fish from an uncontaminated control lake. Concentrations were greatest in white suckers, intermediate in lake whitefish, and low in lake trout. Skin and bone contained the highest radionuclide levels; levels in flesh were much lower. The mean ash-weight concentration of 226Ra in non-control, eviscerated, whole fish was 9.3, 1.8 and 0.8 pCi X g-1 in white suckers, lake whitefish and lake trout respectively. Mean 210Pb levels for those species were 4.0, 1.4 and 0.5 pCi X g-1, while U content was 96.8, 28.2 and 5.8 micrograms X g-1, respectively. Radium-226 content in forage fish ranged from 9.7-70 pCi X g-1. Lead-210 levels ranged from 3.9-55.0 pCi X g-1, while U levels ranged from 15-119 micrograms X g-1. Bioconcentration factors varied among sites, species and tissues. The primary radionuclide transfer pathway appears to be via sediments, either through direct contact or through food organisms. Bottom-feeding species had the highest radionuclide levels while piscivorous fish had the lowest levels. The internal dose rate to non-control fish are comparatively low; any effects are likely to occur at the genetic level.
TL;DR: In this article, the authors proposed a health effects guidance level of 10 pCi/l (0.37 Bq/l) for uranium in drinking water, which is the highest level known to be safe for humans.
Abstract: The interim regulations for radioactivity in drinking water were promulgated in 1976 (Federal Register, Friday, 9 July, 1976, p. 28402). These regulations specifically excluded uranium because of uncertainties concerning its toxicology, treatment technology and occurrence. At this time, EPA's Office of Drinking Water is considering proposing a health effects guidance level of 10 pCi/l. (0.37 Bq/l.) for uranium in drinking water. This paper describes the approach that EPAs Office of Drinking Water is considering in developing the guidance level. This value has not yet been officially determined to be EPA's formal guidance, but is presented as a working hypothesis for review and comments. Included here is a discussion of occurrence, pharmacokinetics and health effects. The calculation of doses uses the ICRP 30 model and the risk determination uses EPA's newly developed life table approach. The risk level from ingesting drinking water with a uranium content of 10 pCi/l. is estimated to be about 3 X 10(-5) excess cancers/lifetime.
TL;DR: By a linear programming procedure, the Jacobi room model is optimized to fit data on the partitioning of radon daughters between air and wall surfaces (plateout), obtained at high radon concentrations in a small chamber, and yielded estimates that compared well with plateout data obtained at lower concentrations at a room-sized chamber.
Abstract: By a linear programming procedure, we have optimized the Jacobi room model to fit our data on the partitioning of radon daughters between air and wall surfaces (plateout), obtained at high radon concentrations in a small chamber. Subsequently, the optimized model yielded estimates that compared well with plateout data obtained at lower concentrations in a room-sized chamber. (The experimental work is described separately.) The major change made in the Jacobi model was to reduce the deposition velocity of free airborne radon daughters from 1 to 0.05 cm/sec. This value was obtained by using a fast algorithm to solve the linear programming to arrive at the "best fit". Lesser changes were made in other parameters.
TL;DR: A mathematical model is offered that describes the general shape of certain dose-response functions when radiation hormesis at low-level exposure is taken into consideration along with the well-known detrimental effects of high-level radiation.
Abstract: Public policy affecting public health regarding effects of low-level ionizing radiations has been, and is being, determined by effects estimates based on linear or other monotonic extrapolation from high-level radiation dose-response data to presumed ecologically realistic low-level exposure effects. Such predictive, unmeasured estimates are very possibly in serious error; they are incompatible with observed low-level dose-response data that indicate a negative correlation between low-level radiation data and health effects, such as cancer mortality rates. Observed negative correlations with low-level radiation data are to be expected on the basis of evidence supporting the validity of the hormesis phenomenon. Hormesis theory, derived in part from evolutionary biology, asserts that while high levels of exposure to an agent such as ionizing radiation are indeed hazardous, ecologically realistic low levels can be stimulatory and largely beneficial. Stimulation of activities of DNA and other repair mechanisms may be involved. Although evidence of the reality of radiation hormesis has been reported in about 1000 scientific publications over the last century, this effect has been largely unrecognized. Moreover, this widespread non-acceptance of hormesis as a real-world phenomenon is usually but not always present in the case of chemical hormesis; the oversight appears systematic. The ignoring of the hormesis phenomenon seems to constitute a very serious error in modern biomedical science and in preventive medicine. A mathematical model is offered that describes the general shape of certain dose-response functions when radiation hormesis at low-level exposure is taken into consideration along with the well-known detrimental effects of high-level radiation.
TL;DR: On 2 September, 1982, one of the employees of the gamma-irradiation facility at The Institute for Energy and Technology (Kjeller, Norway) entered the irradiation cell with a 65.7-kCi 60Co source in unshielded position and died after 13 days.
Abstract: On 2 September, 1982, one of the employees of the gamma-irradiation facility at The Institute for Energy and Technology (Kjeller, Norway) entered the irradiation cell with a 65.7-kCi 60Co source in unshielded position. The victim received an unknown radiation dose and died after 13 days. Using electron-spin resonance spectroscopy (ESR), the radiation dose in this accident was subsequently determined based on the production of long-lived free radicals in nitroglycerol tablets carried by the operator during accident. He used nitroglycerol for heart problems and free radicals are easily formed and trapped in sugar which is the main component of the tablets. Calibration experiments were carried out and the dose given to the tablets during the accident was determined to be 39 Gy. Phantom experiments based on this result indicate an average whole-body dose in the accident of 22.5 Gy.
Journal Article•