why does radium accumulate in bones?

Decay series for radium-228, a beta-particle emitter, and radium-224, an alpha-particle emitter, showing the principal isotopes present, the primary radiations emitted (, , or both), and the half-lives (s = second, m = minute, h (more). 67,68 based on dose, equations that give an acceptable fit are: where the risk coefficient I equals the number of bone sarcomas per person-year at risk that begin to appear after a 5 yr latent period, and D i are as defined above. As of December 1982, the average followup time was 16 yr for patients injected after 1951 with lower doses of 224Ra for the treatment of ankylosing spondylitis.93 Of 1,426 patients who had been traced, the vital status for 1,095 of them was known. 's work,17 the data were plotted against the logarithm of dose so that the low-dose region was not obscured. The analysis of Marshall and Groer38 is noteworthy, not only because it provides a good fit to the data but also because it links dose and events at the cellular level to epidemiological data, an essential step if the results of experimental research at the cellular level are to play a serious role in the estimation of tumor risk at low doses. Occasionally, data from several studies have been analyzed by the same method, and this has helped to illuminate similarities and differences in response among 224Ra, 226Ra, and 228Ra. The take and release of activity into and out of the surface compartment was studied quantitatively in animals and was found to be closely related to the time dependence of activity in the blood.65 Mathematical analysis of the relationship showed that bone surfaces behaved as a single compartment in constant exchange with the blood.37 This model for the kinetics of bone surface retention in animals was adopted for man and integrated into the ICRP model for alkaline earth metabolism, in which it became the basis for distinguishing between retention in bone volume and at bone surfaces. In communities where wells are used, drinking water can be an important source of ingested radium. Schlenker74 examined the uncertainties in risk estimates for bone tumor induction at low intakes and found it to be much greater than would be determined from the standard deviations in fitted risk coefficients. For example, the central value of total risk, including that from natural causes, is I = (10-5 + 6.8 10-8 The rarity of naturally occurring mucoepidermoid carcinoma, contrasted with its frequency among 226,228Ra-exposed subjects, suggests that alpha-particle radiation is capable of significantly altering the distribution of histologic types. If cell survival is an exponential function of alpha-particle dose in vivo as it is in vitro, then the survival adjacent to the typical hot spot, assuming the hot-spot-to-diffuse ratio of 7 derived above, would be the 7th power of the survival adjacent to the typical diffuse concentration. The radium concentration in this layer was 50 to 75 times the mean concentration for the whole skeleton. i between 0.5 and 100 Ci. 1978. i is IN (t - 10) for t Locations of Bone Sarcomas among Persons Exposed to 224 Ra and 226,228Ra for Whom Skeletal Dose Estimates Are Available. The mastoid air cells, like the ethmoid sinuses, are groups of interconnecting air cavities located bilaterally in the left and right temporal bones. Concurrently, Mays and Lloyd44 analyzed the data on bone tumor induction by using Evans' measures of tumor incidence and dosage without correction for selection bias and presented the results in a graphic form that leaves a strong visual impression of linearity, but which, when subjected to statistical analysis, is shown to be nonlinear with high probability. When the sinus becomes unventilated due to ostial closure, the gas composition of the sinus cavity changes and slight overpressure or underpressure may occur.13 When radioactive gases (radon) are present, as with persons exposed to 226,228Ra, there is the potential for a much higher concentration of those gases in the air of the sinus when unventilated than when ventilated. Before concern developed over environmental exposure, attention was devoted primarily to exposure in the workplace, where the potential exists for the accidental uptake of radium at levels known to be harmful to a significant fraction of exposed individuals. No fitted value is given for doses below 1,000 rad, but all data points in this range are at zero incidence. For humans and some species of animals, an abundance of data is available on some of the observable quantities, but in no case have all the necessary data been collected. The best-fit function, however, does contain a linear term, in contrast to the best-fit functions for the data on 226,228Ra. Junho 16, 2022 yardistry gazebo 12x10 yardistry gazebo 12x10 Spiess, H., H. Poppe, and H. Schoen. The use of a table for each starting age group provides a good accounting system for the calculation. s. The analysis also yields good fits to the data. Internal radiation therapy has been used in Europe for more than 40 yr for the treatment of various diseases. In discussing these cases, Wick and Gssner93 noted that three cases of bone cancer were within the range expected for naturally occurring tumors and also within the range expected from a linear extrapolation downward to lower doses from the Spiess et al.88 series. Thurman, G. B., C. W. Mays, G. N. Taylor, A. T. Keane, and H. A. Sissons. With the present state of knowledge, a single dose-response relationship for the whole population according to isotope provides as much accuracy as possible. National Academies Press (US), Washington (DC). Since radium is present at relatively low levels in Low-level endpoints have not been examined with the same thoroughness as cancer. Simple prescriptions for the skeletal dose from 224Ra as a function of injection level have been given by Spiess and Mays85 and can be used to estimate skeletal dose from estimated systemic intake. in the expiratory air . Sarcomas of the bones and joints comprise only 0.24% of microscopically confirmed malignancies reported by the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) program.52 The chance of contracting bone sarcoma during a lifetime is less than 0.1%. Hoecker and Roofe28 determined the dose rate produced by the highest concentrations of radium in microscopic volumes of bone from two former radium-dial painters, one who died in 1927 with an estimated terminal radium burden of 50 g 7 yr after leaving the dial-painting industry, and one who died in 1931 with an estimated terminal burden of 8 g 10 yr after last employment as a dial painter. Hasterlik22 and Hasterlik et al.23 further elucidated the role of radon by postulating that it can diffuse from bone into the essentially closed airspaces of the mastoid air cells and paranasal sinuses and decay there with its daughters, adding an additional dose to the epithelial cells. concluded that linear dose-response function was incapable of describing the data over the full range of doses. In effect, essentially all the 220 Rn that diffuses into the pneumatized air space decays there Before it can be cleared, but essentially all the 222Rn that reaches the pneumatized air space is cleared before it can decay. 1986. For example, if D For the functions of Rowland et al. Autoradiographic studies37 of alkaline earth uptake by bone soon after the alkaline earth was injected into animals revealed the existence of two distinct compartments in bone (see Figure 4-3), a short-term compartment associated with surface deposition, and a long-term compartment associated with volume deposition. They reported that about 50% of the Haversian systems in the os pubis were hot spots, while hot spots constituted only about 2% of the Haversian systems in the femur shaft. Therefore, the minimum observed tumor appearance time is not an absolute lower bound, and there is a small nonzero chance for tumors to occur at doses less than the practical threshold. why does radium accumulate in bones? The first attempts at quantitative dosimetry were those of Kolenkow30 who presented a detailed discussion of frontal sinus dosimetry for two subjects, one with and one without frontal sinus carcinoma. In summary, the evidence indicates that acquisition of very high levels of radium, leading to long-term body contents of the order of 5 Ci or more, equivalent to systemic intakes of the order of several hundred microcuries, resulted in severe anemias and aleukemias. These 28 towns had a total population of 63,689 people in 1970. For the presentation of empirical data, two-dimensional representations are the most convenient and easiest to visualize. This, plus the high level of cell death that would occur in the vicinity of forming hot spots relative to that of cell death in the vicinity of diffuse radioactivity and the increase of diffuse concentration relative to hot-spot concentration that occurs during periods of prolonged exposure led them to postulate that it is the endosteal dose from the diffuse radioactivity that is the predominant cause of osteosarcoma induction. The first explicit description of the structure of the sinus and mastoid mucosa in the radium literature is probably that of Hasterlik,22 who described it as "thin wisps of connective tissue," overlying which "is a single layer of epithelial cells. why does radium accumulate in bones? The alternative is to reanalyze all of the data on tumor induction for 224Ra by using the new algorithm before it is applied it to dose calculations for risk estimation in a population group different from the subjects in the study by Spiess and Mays.85. Adults and juveniles were treated separately. as result of the local effects of the radon . A third compartment, which is not a repository for radium itself but which is relevant to the induction of health effects, consists of the pneumatized portions of the skull bones, that is, the paranasal sinuses and the air cells of the temporal bone (primarily the mastoid air cells), where radon and its progeny, the gaseous decay products of radium, accumulate. However, no mention of such cases appear in his report. Table 4-7 illustrates the effect, assuming that one million U.S. white males receive an excess skeletal dose of 1 rad from 224Ra at age 40. This study was aimed at the role, if any, of trihalomethanes resulting from the disinfection of water by chlorination. A mechanistic model for alkaline earth metabolism29 was developed by the ICRP to describe the retention of calcium, strontium, barium, and radium in the human body and in human soft tissue, bone volume, bone surfaces, and blood. Tumor frequencies for axial and appendicular skeleton are shown in Table 4-1. emergency sirens spiritual meaning junio 29, 2022. cotton patch gospel quotes 10:06 am 10:06 am Commenting on the mucosal thickness data of Ash and Raum,2 Littman et al.31 observed: "If the dimensions of the sinus walls are applicable to the radium cases, it would appear that only a relatively sparse population of epithelial cells in the submucosal glands of the paranasal sinuses would receive significant dose from alpha particles originating in bone.". The distribution of histologic types for radium-induced tumors is compared in Table 4-2 with that reported for naturally occurring bone tumors.11 The data have been divided into two groups according to age of record for the tumor. The normally functioning sinus is ventilated; that is, its ostium or ostia are open, permitting the free exchange of gases between the sinus and nasal cavities. Radium deposited in bone irradiates the cells of that tissue, eventually causing sarcomas in a large fraction of subjects exposed to high doses. The data have been normalized to the frequency for osteosarcoma and limited to the three principal radiogenic types: osteosarcoma, chondrosarcoma, and fibrosarcoma. Annual Report No. Fact Sheet #29 Radium-226 ( 226Ra) Page 3 of 3 Direct observations of the lamina propria indicate that the thickness lies between 14 and 541 m.21. If radium is ingested or inhaled, the radiation emitted by the radionuclide can interact with cells and damage them. Raabe, O. G., S. A. The primary sources of information on the health effects and dosimetry of radium isotopes come from extensive studies of 224Ra, 226Ra, and 228Ra in humans and experimental animals. Some of the lead can stay in the bones for decades; however, some lead can leave the bones and reenter the blood and organs under certain circumstances, for example, during pregnancy and periods of breast-feeding, after a bone demonstrated an increase of median tumor appearance time with decreasing average skeletal dose rate for a subset of radium-induced bone tumors in humans61 and for bone tumors induced in experimental animals by a variety of radionuclides.60 The validity of the analysis of mouse data has been challenged,62 but not the analysis of human and dog data. Based on this, the chance of randomly selecting three tumors from the this distribution and coming up with no osteosarcomas is about (0.2)3 = 0.008, throwing the weight of evidence in favor of a nonradiogenic origin for the three bone cancers found in this study.93,94 However, this could occur if there were a dramatic change in the distribution of histologic types for tumors induced by 224Ra at doses below about 90 rad, which is approximately the lower limit for tumor induction in the Spiess et al.88 series. A recent examination of data on whole-body radium retention in humans revealed that the excretion rate diminished with increasing body burden.70 Absolute retention could not be studied, because the initial intake was unknown, but the data imply the existence of a dose-dependent retention similar to that observed in animals. This type of analysis updates the one originally conducted for this group of subjects in which juvenile radiosensitivity was reported to be a factor of 2 higher than adult radiosensitivity. The second analysis is that of Marshall and Groer,38 in which a carefully constructed theoretical model was fitted to bone-cancer incidence data. Parks. where 3 10-5 is the natural risk adapted here. The linear relationship that provided the best fit to the data predicted a tumor rate lower than the rate that had been observed recently, and led the authors to suggest that the incidence at long times after first exposure may be greater than the average rate observed thus far. All members of the world's population are presumably at risk, because each absorbs radium from food and water; as a working hypothesis, radiation is assumed to be carcinogenic even at the lowest dose levels, although there is no unequivocal evidence to support this hypothesis. The most inclusive and definitive study of leukemia in the U.S. radium-dial workers was published by Spiers et al.83 By including all the dial workers, male and female, who entered the industry before 1970, a total of 2,940 persons who could be located, they were able to document a total of 10 cases of leukemia. For 228Ra the dose rate from the airspace to the mastoid epithelium was about 45% of the dose rate from bone. Groer and Marshall20 estimated the minimum time for osteosarcoma appearance in persons exposed to high doses of 226Ra and 228Ra. National Research Council (US) Committee on the Biological Effects of Ionizing Radiations. This is the first report of an explicit test of linearity that has resulted in rejection. These are supplemented by postmortem measurements of skeletal and soft-tissue content, observations of radium distribution within bone on a microscale, and measurements of radon gas content in the mastoid air cells. why does radium accumulate in bones? 1975. Radium is highly radioactive. For each of the seven intake groupings in this range (e.g., 0.51, 12.5, 2.55), there was about a 5% chance that the true tumor rate exceeded 10-3 bone sarcomas per person-year when no tumors were observed, and there was a 48% chance that the true tumor rate, summed over all seven intake groups exceeded the rate predicted by the best-fit function I = (10-5 + 6.8 10-8 The expected number, however, is only 1.31. Cells with a fibroblastic appearance similar to that of the cells lining normal bone were an average distance of 14.9 m from the bone surface compared with an average distance of 1.98 m for normal bone.