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PubMedDate not supplied

The application and adaptation of ICRP internal dosimetry models to the calculation of bone marrow tissue doses from 90Sr for epidemiological studies of Techa River populations.

The operation of the Mayak Production Association in the Southern Urals region of Russia, resulted in releases of large amounts of radioactive effluent into the Techa River during the period 1949-1956. The residents of the riverside communities were thus exposed to both external radiation, and internal radiation following ingestion of contaminated water and foodstuffs. One of the most important radionuclides for internal exposure was 90Sr. This paper gives a brief overview of the models provided by International Commission on Radiological Protection (ICRP), which are of interest for assessing internal doses from 90Sr. The application of these models to the calculation of red bone marrow doses for the fetus and infant from 90Sr intakes by the mother and the infant is illustrated by an example. A hypothetical individual born in 1951 is used as an example for dose calculations. The following doses due to intakes of 90Sr are taken into account: received in utero due to maternal intakes during pregnancy; received after birth from 90Sr accumulated by the fetus in utero; from intakes in breast milk; from intakes in the infant's diet after weaning. It is shown that doses to the fetus following maternal ingestion and subsequent transfer to the fetus via the placenta dominate the doses received for this particular individual for the first two years of life. Doses to the infant from intakes in breast milk are substantially lower but do make significant contributions to total doses in the first two years after birth. By about the age of two years residual 90Sr from placental transfer still contributes about the same dose as do intakes by the infant, but in later years doses from intakes by the infant dominate.

Bone Marrow↗
PubMed1992

Investigations of radiocaesium in the natural terrestrial environment in Norway following the Chernobyl accident.

Radioactive fallout from the Chernobyl accident affected parts of central Norway to a considerable extent, in particular the 134Cs+137Cs deposition had a significant impact on the natural environment. When this became apparent, a comprehensive radioecological research programme was initiated in order to study the behaviour of radiocaesium in boreal and alpine ecosystems, with emphasis on food-chains leading to exposure of species used for human consumption, i.e., reindeer and freshwater fish. In this paper results from the terrestrial part of this research programme during the period 1986-1990 are presented. The work was mainly confined to the mountain areas of Dovre and Rondane. Parallel studies were performed in eutrophic and strongly oligotrophic communities. The influence of local variations in topography and microclimate on the observed radiocaesium levels in topsoils, lichens and vascular plants was studied in detail. Currently a significant re-distribution of radiocaesium from the originally strongly exposed surfaces to those that were less exposed is observed. In the soil, radiocaesium is strongly retained in the litter and raw humus layers. Current levels in lichens are 1-2 orders of magnitude higher than in vascular plants. This strongly affects the seasonal variation of radiocaesium in reindeer, showing winter maxima of about 5 times higher than the August levels. The radiocaesium levels in reindeer showed a decline of approximately a factor of 3 during the period 1987-1990. Other animal species studied in the programme exhibited substantially lower radiocaesium levels than reindeer, but a considerable interspecies variation was observed.

Accidents↗
PubMed1997

Radiation doses to critical groups since the early 1950s due to discharges of liquid radioactive waste from Sellafield.

First, some of the early work is reviewed on exposure pathways in connection with proposed and early liquid radioactive waste discharges from Sellafield. The main historical features of these discharges, affected by relevant plant operations, are then briefly described. The important radiological exposure pathways resulting from the discharges and people's consumption and occupancy habits are considered. To place the changing scenario onto a consistent basis using present-day methodology, a reconstruction of exposures has been carried out using environmental monitoring data and models. The three major pathways are examined of Porphyra/laverbread consumption in South Wales, fish and shellfish consumption near Sellafield, and external exposure over local and more distant sediments. The results show that over the period 1952 to about 1970 the laverbread pathway was probably critical, taking a cautious approach. Effective dose rates fluctuated at around 1 mSv y(-1) from about 1956 to 1971. From about 1970 to 1985, the fish and shellfish pathway was likely to have been critical, with effective dose rates peaking at about 2 mSv y(-1) in 1975-1976. External exposure was likely to have been of lesser importance than the other two pathways until about 1985, when with the retention of previously-released radiocesium on sediments it has become dominant. This phenomenon applies particularly further afield where radiocesium concentrations have been slower to decline; in the Ribble estuary, houseboat dwellers have been the critical group from about 1985. Effective doses have been at about 0.3 mSv y(-1) and declining; they are due to the effects of radiocesium discharges in earlier years. Dose rates have remained within contemporary ICRP dose limits.

Actinoid Series Elements↗
PubMed1989

An assessment of soil-to-plant concentration ratios for some natural analogues of the transuranic elements.

A field study was conducted in an area of enhanced, natural radioactivity to assess the soil to edible vegetable concentration ratios (CR = concentration in dry vegetable/concentration in dry soil) of 232Th, 230Th, 226Ra, 228Ra, and the light rare earth elements (REE's) La, Ce and Nd. Twenty-nine soil and 42 vegetable samples consisting of relatively equal numbers of seven varieties were obtained from 11 farms on the Pocos de Caldas Plateau in the state of Minas Gerais, Brazil. This region is the site of a major natural analogue study to assess the mobilization and retardation processes affecting Th and the REE's at the Morro do Ferro ore body and U series radionuclides at a nearby open pit U mine. Thorium (IV) serves as a chemical analogue for quadrivalent Pu and the light REE's (III) as chemical analogues for trivalent Am and Cm. The geometric mean CR's (all times 10(-4] decreased as 228Ra (148) greater than 226Ra (76) greater than La (5.4) greater than Nd (3.0) = Ce (2.6) greater than 232Th (0.6), or simply as M (II) greater than M (III) greater than M (IV). These differences may reflect the relative availability of these metals for plant uptake. Significant differences were found in the CR's (for any given analyte) among many of the vegetables sampled. The CR's for the different analytes were also highly correlated. The reasons for the correlations in CR's seen among elements with such diverse chemistries as Ra-REE or Ra-Th are not clear but are apparently related to the essential mineral requirements or mineral status of the different vegetables sampled. This conclusion is based on the significant correlations obtained between the Ca content of the dried vegetables and the CR's for all of the elements studied.

Background Radiation↗
PubMed2004

The combined impact on doses to man of multiple, authorized, radionuclide discharges for the year 1999 reaching the upper river thames, uk.

Before issuing a new or revised authorization to discharge liquid radioactive waste to a river, past and current practice has been to assess the impact of each discharge on a site-by-site basis. This paper reports an assessment of the combined impact of all the (year 1999) authorized discharges in the upper River Thames (UK) catchment. A modification of the PC-CREAM model, using parameters specific to the upper River Thames, was used to estimate "potential doses" to the population, using the authorized discharge activity for each of the discharges as the main driving variable. The main purpose of this study was to investigate the difference in doses between single and multiple discharges in the Thames. A partial validation of the model against measurements was also carried out as a secondary investigation. The source term of the upper Thames consisted of 90 authorized discharges for 86 sites, made up of three nuclear licensed sites, 36 industrial discharges, 25 research organizations, 20 hospitals and two miscellaneous organizations. Of the authorized discharges, nuclear sites constituted 67% of the total activity in authorizations to discharge; hospitals 16%, research organizations 13%, and industry only 3%. Three radionuclides made up 96% of the total authorized discharge activity: tritium-74%; Tc-15%, and C-7%. No other single radionuclide constituted more than 1.5% of the total activity. All of the discharges from non-nuclear sites were via a sewage works so that, in total, only 39 discrete discharges to the river were included in the model. For the purposes of the assessments, it was assumed that all discharges were at the authorized limits (rather than using actual discharge). Even with this maximizing assumption, all the calculated potential doses from the combined source terms were significantly less than the radiation dose limit of 1 mSv y for a member of the public. The highest estimated potential doses were investigated further to identify the major pathways. Ingestion of fish was the main pathway in several river stretches and in the highest case constituted 97% of the dose. In a few stretches, external irradiation from the riverbank or ingestion of drinking water were the main pathways, but the potential contribution was a very small percentage (<1%) of the dose limit for members of the public. An investigation of the reasons for the relatively high potential doses resulting from fish showed that the radionuclide with the largest contribution was P. Three factors had a major effect on potential dose estimations in these circumstances: the fish consumption rate, the P concentration factor and the use of P in some cases to represent radionuclides authorized for discharge as "any other radionuclide, except alpha emitters." Using the precautionary principle, all authorized activity in the latter designation was modeled as the radionuclide which would produce the highest dose to humans.

Adult↗
PubMed1994

Comprehensive RNAA of cadmium, cobalt, nickel, and copper using 109Cd, 57Co, and reactor-produced 67Cu as radioisotopic yield monitors.

An existing radiochemical NAA procedure for Cd, Co, and Cu was improved to allow determination of individual radiochemical yields by the radioisotopic tracer technique, thus eliminating errors owing to variable recovery. 109Cd was used as tracer for Cd determination via 115Cd/115mIn, 57Co for Co via 60Co, and potentially for Ni via 58Co, whereas as a novelty 67Cu, produced by reactor irradiation of ZnO of natural isotopic composition (by the 67Zn [n,p] 67Cu reaction) was used for Cu via the indicator nuclide 64Cu. The simple production and purification of 67Cu by anion exchange is described. Results for biological RMs are given and discussed.

Animals↗
PubMed1978

The movement of plutonium, americium, and curium through the food chain.

The actinides, plutonium, americium and curium, are being produced in increasing quantites as the nuclear programme is expanded. As these alpha-particle-emitting elements are hazardous to man there is considerable concern about the movement of these elements through the environment; The uptake of these elements from soil into the plants is low, as is the gastrointestinal concentration factor. Although there are complexing agents in the environment which have been shown to complex these elements there is no evidence that these complexing agents might bring about a concentration of actinides in the food chain of man.

Actinoid Series Elements↗
PubMed1989

[Thorium in soil, vegetables, cereals and fruit].

Thorium contents (alpha-activities of the naturally occurring isotopes Th-228, Th-230, and Th-232) were determined in soils, vegetables, cereals, and fruits. The thorium content of plants depends on the degree of contamination by soil resuspension and thus on the specific surface of the plants. The activity of the isotope Th-230 is almost the same as that of the main isotope Th-232. Th-228, with about the same activity as Th-232 in soil, increases to about 10-fold the activity in vegetables, 29-fold in sweet chestnuts and 740-fold in Brazil nuts. Thorium concentration factors from the soil to these vegetable products are calculated; they include the total concentration, not only the soluble portion of thorium.

Edible Grain↗
PubMed1989

[The transfer of 137Cs and 90Sr into flour, bran and straw from wheat, rye, barley and oats in the years 1982, 1986 (reactor accident in Chernobyl) and 1987 in field studies].

The specific activity of 137Cs and 90Sr from the global fallout, as well as from the fallout after the reactor accident at Chernobyl, was determined in flour, bran and straw from wheat, rye, barley and oats as well in the corresponding soils (Cambisol). The results show that the activity of 137Cs, but not of 90Sr, in the plant material was considerably higher in 1986, and still to some extent in 1987, compared to 1982. For 137Cs an 90Sr, as well as for most cereal samples, the activity in the bran and straw was significantly higher than in the flour. Determination of stable potassium and calcium in all samples revealed that this enrichment is, to a large extent, the result of a comparable enrichment of these elements in brans and straw. The plant/soil concentration ratios, averaged over all cereals, were for 137Cs (1982 and 1987): flour 0.026 +/- 0.018; bran 0.079 +/- 0.042; straw 0.055 +/- 0.027. For 90Sr (1982, 1986, and 1987): flour 0.19 +/- 0.095; bran 0.70 +/- 0.23; straw 2.35 +/- 0.82.

Accidents↗
PubMed1990

[Cesium 134 and 137 contamination of game killed in Hesse].

The amount of caesium 134 and 137 in Hessian game hunted for food (556 animals) after the reactor accident at Chernobyl was investigated. Comparisons have been made before and after the accident. Although there was only a very low level of contamination, the contamination rate of different species varied; on average, the Red Deer showed the highest activity (130 Bq/kg). The level of caesium contamination was mostly influenced by the permanent habitat of the animals. The main influence was due to regional, geographical and meteorological conditions. The influence of age or sex could not be determined. The contamination rate was shown to decrease with time.

Accidents↗
PubMed1992

[Thorium amd uranium in food of animal origin].

The thorium and uranium contents (alpha-activities of the natural isotopes Th-228, Th-230, Th-232, U-234, and U-238) in several samples of the meat of domestic animals, venison, and cold-blooded animals are reported. The activity of thorium and of uranium was surprisingly constant in lean meat of all the animals tested. The average activity of the main isotope of thorium was 1-2 mBq Th-232/kg fresh meat (FM) and of uranium 21-34 mBq U-238/kg FM. The lowest and highest values observed were 0.4 and 2.7 mBq Th-232/kg FM, and 9 and 41 mBq U-238/kg FM, respectively. In some internal organs distinctly higher values were obtained: 8.6 mBq Th-232/kg in cattle bones, and 51 mBq U-238/kg in hog kidneys. The highest content of U-238, 84 mBq/kg, was observed in cuttlefish (whole animal). In lean meat, the activity of the daughter isotope Th-228 was on average (by factor) two to four times higher than that of the parent isotope Th-232. In cattle bones, and in fish samples including bones, the factor was 20 and 26, respectively. The activity of the isotope Th-230 ranged between Th-232 and Th-228. In all samples investigated, the daughter isotope U-234 showed an excess activity of 19 +/- 7% as compared to the parent isotope U-238. The above nuclides were determined alpha-spectrometrically using Th-229 for thorium, and U-232 for uranium as internal standard.

Animals↗
PubMed1996

Development and testing of a revised dynamic model of radiocaesium transfer to sheep tissues.

The model of radiocaesium transfer to sheep presented by Galer et al. provides reliable predictions only for sheep of a similar body weight to those used in the development of the model (approximately 30 kg). To extend the applicability of the model, it was necessary to re-parameterise it in terms of activity concentrations in tissues rather than total activities within them (although for gut compartments the use of activity has been retained). The rate coefficients for the new model have been estimated by fitting the model to the data used by Galer et al. which was derived from a single "calibration" experiment. The new model was found to account for 94% of the observed variation in the data (n = 42), a result similar to that obtained by Galer et al. The model has also been tested against data not used in its development but obtained from four separate experiments undertaken by three different laboratories. Good agreement between the predictions of the new model and observations was found for most circumstances and for several breeds of sheep with different body weights. It is concluded that the new model provides a useful dynamic description of radiocaesium transfers to the tissues of sheep of different breeds and under different contamination scenarios.

Administration, Oral↗
PubMed1980

Lead-210 content of food samples in India.

The paper presents results of measurements made on cereals and composite meal samples collected from Bombay market for their lead-210 content. The details of sampling and analytical chemistry procedures are also given. The Pb210 contents of most of these samples were in the range of 1--5 pCi/kg of cereals samples. The concentrations in composite meal samples were mostly in the range of 1--3.5 pCi of 210Pb per composite meal. The assessment of daily intake of this isotope through food-stuffs has been made.

Edible Grain↗
PubMedDate not supplied

Whole body content and turnover of Cs and K.

In persons who had accumulated radiocesium from the fallout of the Chernobyl nuclear reactor accident, the amount of radiocesium and radiopotassium was measured in the total body and in urine. The stable Cs content in the urine was determined at the same time by instrumental nuclear activation analysis. From the data obtained, the total body Cs pool was calculated to be 1500 micrograms, that of K 110 g. The Cs turnover rate was found to be 0.64%/d for men and 0.81 for women; the K turnover 2.4 and 2.7, respectively. The Cs:K ratio in the total body was 4 times higher than that in urine, demonstrating that, in relation to the intake, the body is able to accumulate more Cs than K.

Accidents↗
PubMed2002

Non-medical exposure to radioiodines and thyroid cancer.

The Chernobyl accident, which occurred 32 years after the accidental exposure of Marshall islanders, resulted in the exposure of neighbouring populations to a mixture of iodine isotopes and in an increased incidence of thyroid cancer. The highest thyroid doses were received by the youngest age groups. This review describes the existing evidence, and examines factors that may have increased the risk. It also stresses problems with contemporary thyroid measurements, and the lack of information on the sensitivity of the thyroid to short-lived iodine isotopes and iodine-131. Practical considerations for nuclear physicians, epidemiologists and thyroidologists are discussed in the light of this major accident.

Accidents↗