1958. radiation Flashcards by Ellie Atkinson | Brainscape However, calcium is ubiquitous in the human body, so small amounts of radium may accumulate in other tissues, causing toxicity. Although this city draws its water from Lake Michigan, where the radium concentration is reported as 0.03 pCi/liter, the age- and sex-adjusted osteosarcoma mortality rate was 6.3/million/yr, which is larger than that found for the towns with elevated radium levels in their water. Regardless of the functions selected as envelope boundaries, however, the percent uncertainty in the risk cannot be materially reduced. These authors concluded that there was no relationship between radium level and the occurrence of leukemia. 1972. The analysis shows that the minimum appearance time varies irregularly with intake (or dose) and that the rate of tumor occurrence increases sharply at about 38 yr after first exposure for intakes of greater than 470 Ci and may increase at about 48 yr after first exposure for intakes of less than 260 Ci. This type of analysis was used by Evans15 in several publications, some of which employed epidemiological suitability classifications to control for case selection bias. Five of these cases of leukemia were found in a group of approximately 250 workers from radium-dial painting plants in Illinois. 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. 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. Spiess, H., H. Poppe, and H. Schoen. The poorest fit, and one that is unacceptable according to a chi-squared criterion, was obtained for I = C + D2. i 2 for D For the percent of exposed persons with bone sarcomas, Mays and Lloyd44 give 0.0046% D 1969. Calcium Beyond the Bones - Harvard Health -kx), and a threshold function. ; Volume 35, Issue 1, of Health Physics; the Supplement to Volume 44 of Health Physics; and publications of the Center for Human Radiobiology at Argonne National Laboratory, the Radioactivity Center at the Massachusetts Institute of Technology, the New Jersey Radium Research Project, the Radiobiology Laboratory at the University of California, Davis, and the Radiobiology Division at the University of Utah. 1978. Schlenker74 presented a series of analyses of the 226,228Ra tumor data in the low range of intakes at which no tumors were observed but to which substantial numbers of subjects were exposed. The cause of paranasal sinus and mastoid air cell carcinomas has been the subject of comment since the first published report,43 when it was postulated that they arise ''. For 224Ra, 226Ra, and 228Ra the best-available relationships are based on different measures of exposure: absorbed skeletal dose for 224Ra and systemic intake for 226Ra and 228Ra. For exposure at environmental levels, the distinction between hot spots and diffuse radioactivity is reduced or removed altogether. (a), Mays and Lloyd (b), and Rowland et al. When the time dependence of bone tumor appearance following 224Ra exposure is considered an essential component of the analysis, then an approximate modification of the dose-response relationship can be made by taking the product of the dose-response equation and an exponential function of time to represent the rate of tumor appearance: where F(D) is the lifetime risk, as specified by the analyses of Spiess and Mays85 and r is a coefficient based on the time of tumor appearance for juveniles and adults in the 224Ra data analyses. When an excess has occurred, there exist confounding variables. Various radiation effects have been attributed to radium, but the only noncontroversial ones are those associated with the deposition of radium in hard tissues. With life-long continuous intake of dietary radium, the distinction between hot spot and diffuse activity concentrations is diminished; if dietary intake maintains a constant radium specific activity in the blood, the distinction should disappear altogether because blood and bone will always be in equilibrium with one another, yielding a uniform radium specific activity throughout the entire mineralized skeleton. The probability of such a difference occurring by chance was 51%. The increase of diffuse activity relative to hot-spot activity, which is suggested by Marshall and Groer38 to occur during prolonged intake, has a strong theoretical justification. In people with radium burdens of many years' duration, only 2% of the excreted radium exits through the kidneys. Below this dose level, the chance of developing a radium-induced tumor would be very small, or zero, as the word threshold implies. PDF EPA Facts about Radium The outcome of the analyses of Rowland and colleagues was the same whether intake or average skeletal dose was employed, and for comparison with the work of Evans and Mays and their coworkers, analyses based on average skeletal dose will be used for illustration. Rowland, R. E., A. T. Keane, and P. M. Failla. This is the first report of an explicit test of linearity that has resulted in rejection. D . A necessary first step for the estimation of risk from any route of intake other than injection is therefore to apply these models. If radium is ingested or inhaled, the radiation emitted by the radionuclide can interact with cells and damage them. The success achieved in fitting dose-response functions to the data, both as a function of intake and of dose, indicates that the outcome is not sensitive to assumptions about tumor rate. 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. However, 80% of the bone tumors in the this series, for which histologic type is known, are osteosarcomas, while fibrosarcomas and reticulum cell sarcomas each represent only about 2% of the total, and multiple myeloma was not observed at all. 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 an earlier summary for 24 224Ra-induced osteosarcomas,90 21% occurred in the axial skeleton. The average dose for the exposed group, based on patients for whom there were extant records of treatment level, was 65 rad. Restated in more modern terms, the residual range from bone volume seekers (226Ra and 228Ra) is too small for alpha particles to reach the mucosal epithelium, but the range may be great enough for bone surface seekers (228Th), whose alpha particles suffer no significant energy loss in bone mineral;78 long-range beta particles and most gamma rays emitted from adjacent bone can reach the mucosal cells, and free radon may play a role in the tumor-induction process. 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. Petersen, N. J., L. D. Samuels, H. F. Lucas, and S. P. Abrahams. Thus, the spectrum of tumor types appears to be shifted from the naturally occurring spectrum when the tumors are induced by radium. The data have been normalized to the frequency for osteosarcoma and limited to the three principal radiogenic types: osteosarcoma, chondrosarcoma, and fibrosarcoma. The principal factors that have been considered are the nonuniformity of deposition within bone and its implications for cancer induction and the implications for fibrotic tissue adjacent to bone surfaces. It is not known whether the similarity in appearance time distribution for the two tumor types under similar conditions of irradiation of bone marrow is due to a common origin. Rowland et al. employed a log-normal dose-rate, time-response model that was fitted to the data and that could be used to determine bone-cancer incidence, measured as a percentage of those at risk, versus absorbed skeletal radiation dose. This yielded a dose rate of 0.0039 rad/day for humans and a cumulative dose of 80 rads to the skeleton.61. i = 0.5 Ci, the lower boundary of the lowest intake cohort used when fitting functions to the data. The radium, once ingested, behaves chemically like calcium and, therefore, deposits in significant quantities in bone mineral, where it is retained for a very long time. 1985. i Kolenkow's work30 illustrated many of the complexities of sinus dosimetry and emphasized the rapid decrease of dose with depth in the mucous membrane. The heavy curve represents the new model. Whole-body radium retention in humans. i = 0.5 Ci. It shows no signs of significant secretory activity but is always moist. Your comment on the increased blood flow is certainly part of the process, especially for acute (recent) injuries. As revealed by animal experiments and clearly detailed by metabolic models, alkaline earth elements deposit first on bone surfaces and then within the volume of bone. This is evidenced by the fact that bone tumor incidence rises to 100% with increasing dose. He emphasized that current recommendations of the ICRP make no clear distinction between the locations of epithelial and endosteal cells and leave the impression that both cell types lie within 10 m of the bone surface; this leads to large overestimates of the dose to epithelial cells from bone. 1986. Included in the above summary are four cases of chronic lymphocytic or chronic lymphatic leukemia. D For five subjects on whom he had autoradiographic data for the 226Ra specific activity in bone adjacent to the mastoid air cells, the dose rate at death from 222Rn and its daughters in the airspaces exceeded the dose rate from 226Ra and its daughters in bone. At high radiation doses, whole-body retention is dose dependent. Such negative values follow logically from the mathematical models used to fit the data and underscore the inaccuracy and uncertainty associated with evaluating the risk far below the range of exposures at which tumors have been observed. This may lead to negative values at low exposures. In spite of these differences, 224Ra has been found to be an efficient inducer of bone cancer. When radiogenic risk is determined by setting the natural tumor rate equal to 0 in the expressions for total risk and by eliminating the natural tumor rate (10-5/yr) from the denominator in Equation 4-14, the value of the ratio increases more slowly, reaching 470 at D These estimates are based on retention integrals74 and relative distribution factors40 that originate from retention and dosimetry models. A. Egsston. The purpose of this chapter is to review the information on cancer induced by these three isotopes in humans and estimate the risks associated with their internal deposition. Stebbings et al.89 published results of a mortality study of the U.S. female radium-dial workers using a much larger data base. The dose is delivered continuously over the balance of a person's lifetime, with ample opportunity for the remodeling of bone tissues and the development of biological damage to modulate the dose to critical cells. Spiers, F. W., H. F. Lucas, J. Rundo, and G. A. Anast. 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. 1957. If the survival adjacent to the diffuse component were 37%, as might occur for endosteal doses of 50 to 150 rad, the hot-spot survival would be 0.09%. They based their selection on the point of intersection between the line representing the human lifetime and "a cancer risk that occurs three geometric standard deviations earlier than the median." The best fit was obtained for the functional form I =(C + D) exp(-D), an unacceptable fit was obtained for I = C + D2, and all other forms provided acceptable fits. He also estimated dose rates for situations where there were no available autoradiographic data. Once radium-223 reaches bone, it emits alpha-particle radiation, which induces double stranded breaks in DNA, causing a local cytotoxic effect [ 6, 8 ]. The time course for development of fibrosis and whether it is a threshold phenomenon that occurs only at higher doses are unknown. A significant role for free radon and the possibly insignificant role for bone volume seekers is not universally acknowledged; the ICRP lumps the sinus and mastoid mucosal tissues together with the endosteal bone tissues and considers that the dose to the first 10 m of tissue from radionuclides deposited in or on bone is the carcinogenically significant dose, thus ignoring trapped radon altogether and taking no account of the epithelial cell locations which are known to be farther from bone than 10 m. In the case of the longer-half-life radium isotopes, the interpretation of the cancer response in terms of estimated dose is less clear. Such cells could accumulate average doses in the range of 100300 rad, which is known to induce transformation in cell systems in vitro. Schlenker and Smith80 also reported incomplete retention for 212Pb and concluded that the actual endosteal dose rate 24 h after injection varied between about one-third and one-half of the equilibrium dose rate for their experimental animals. 1972. Stebbings, J. H., H. F. Lucas, and A. F. Stehney. Individuals may be exposed to higher levels of radium if they live in an area where there are higher levels of radium in rock and soil. There is little evidence for an age or sex dependence of the cancer risk from radium isotopes, provided that the age dependence of dose that accompanies changes in body and tissue masses is taken into account. For t less than 5 yr, M(D,t) is essentially 0 because of the minimum latent period. Nevertheless, the time that bone and adjacent tissues were irradiated was quite short in comparison to the irradiation following incorporation of 226Ra and 228Ra by radium-dial workers. The above results, based on observations of several thousand individuals over periods now ranging well over 50 yr, make the recent report by Lyman et al.35 on an association between radium in the groundwater of Florida and the occurrence of leukemia very difficult to evaluate. It should be noted that if tumor rate were constant for a given dose, it could not be constant for a given intake because the dose produced by a given intake is itself a function of time; therefore, the tumor rate would be time dependent. 1981. As the practical concerns of radiation protection have shifted and knowledge has accumulated, there has been an evolution in the design and objectives of experimental animal studies and in the methods of collection, analysis, and presentation of human health effects data. The weight of available evidence suggests that bone sarcomas arise from cells that accumulate their dose while within an alpha-particle range. Also, mortality statistics as they now exist include the effect of environmental exposures to radium isotopes. Direct observation in vivo of retention in these three compartments is not possible, and what has been learned about them has been inferred from postmortem observations and modeling studies. Evans, R. D., A. T. Keane, and M. M. Shanahan. He took into account the dose rate from 226Ra or 228Ra in bone, the dose rate from 222Rn or 220Rn in the airspaces, the impact of ventilation and blood flow on the residence times of these gases in the airspaces, measured values for the radioactivity concentrations in the bones of certain radium-exposed patients, and determined expected values for radon gas concentrations in the airspaces. The loss is more rapid from soft than hard tissues, so there is a gradual shift in the distribution of body radium toward hard tissue, and ultimately, bone becomes the principal repository for radium in the body. Mays et al.50 reported on the follow-up of 899 children and adults who received weekly or twice-weekly intravenous injections of 224Ra, mainly for the treatment of tuberculosis and ankylosing spondylitis. With a lifetime natural tumor risk of 0.1%, the radiogenic risk would be -0.0977%. It does, however, deposit in soft tissue and there is a potential for radiation effects in these tissues. Phosphorites are rocks that are made of apatite, a mineral with the formula C a X 5 ( P O X 4) X 3 ( F, C l, O H). The type of dose used is stated for each set of data discussed. Higher doses of radium have been shown to cause effects on the blood (anemia), eyes (cataracts), teeth (broken teeth), and bones (reduced bone growth). 1982. For the analyses based on intake, the equation that gives an acceptable fit is: where I is bone sarcomas per person-year at risk, and D 1978. The radium concentration in this layer was 50 to 75 times the mean concentration for the whole skeleton. The other 98% passes out through the bowel. For the sinuses alone, the distribution of types is 40% epidermoid, 40% mucoepidermoid, and 20% adenocarcinoma, compared with 37, 0, and 24%, respectively, of naturally occurring carcinomas in the ethmoid, frontal, and sphenoid sinuses.4 Among all microscopically confirmed carcinomas with known specific cell type in the nasal cavities, sinuses and ear listed in the National Cancer Institute SEER report,52 75% were epidermoid, 1.6% were mucoepidermoid, and 7% were adenocarcinoma. Incident Leukemia in Located Radium Workers. Internal radiation therapy has been used in Europe for more than 40 yr for the treatment of various diseases. 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. What I can't discover is why our body prefers these higher atomic weight compounds than the lower weight Calcium. During the first few days after intake, radium concentrates heavily on bone surfaces and then gradually shifts its primary deposition site to bone volume. In Table 4-1 note the low tumor yield of the axial compared with the appendicular skeleton. 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 These 28 towns had a total population of 63,689 people in 1970. 1969. PDF Health Effects of Lead Exposure Introduction - Oregon Radiation Safety Flashcards | Quizlet We make safe shipping arrangements for your convenience from Baton Rouge, Louisiana. a. A common reaction to intense radiation is the development of fibrotic tissue. Research should continue on the cells at risk for bone-cancer induction, on cell behavior over time, including where the cells are located in the radiation field at various stages of their life cycles, on tissue modifications which may reduce the radiation dose to the cells, and on the time behavior and distribution of radioactivity in bone. Effects of radiation on bone - PubMed Whether the practical threshold represents a dose below which the tumor risk is zero, or merely tiny, depends on whether the minimum tumor appearance time is an absolute boundary below which no tumors can occur or merely an apparent boundary below which no tumors have been observed to occur in the population of about 2,500 people for whom radium doses are known. i If forms with negative coefficients are eliminated, as postulated by the model, then only (C + D) exp(-D) from this latter group provided an acceptable fit, but it had a chi-squared probability (0.06) close to the rejection level (0.05). These body burden estimates presumably include contributions from both 226Ra and 228Ra. 1983. Bean, J. s, where D 1959. International Commission on Radiological Protection (ICRP). Working from various radium-exposed patient data bases, several authors have observed that carcinomas of the paranasal sinuses and mastoid air cells begin to occur later than bone tumors.16,18,66,71 In the latest tabulation of tumor cases,1 the first bone tumor appeared 5 yr after first exposure, and the first carcinoma of the paranasal sinuses or mastoid air cells appeared 19 yr after first exposure; among persons for whom there was an estimate of skeletal radiation dose, the first tumors appeared at 7 and 19 yr, respectively. When one considers that endosteal doses from the diffuse component among persons exposed to 226,228Ra who developed bone cancer ranged between about 250 and 25,000 rad, it becomes clear that the chance for cell survival in the vicinity of the typical hot spot was infinitesimal. They also presented an equation for depth dose from radon and its daughters in the airspace for the case of a well-ventilated sinus, in which the radon concentration was equal to the radon concentration in exhaled breath. Direct observations of the lamina propria indicate that the thickness lies between 14 and 541 m.21. Error bars on the points vary in size, and are all less than about 6% cumulative incidence (Figure 4-4). 1986. The ratio of the 95% confidence interval range, for radiogenic risk, to the central value. The frequencies for different bone groups are axial skeleton-skull (3), mandible (1), ribs (2), sternebrae (1), vertebrae (1), appendicular skeleton-scapulae (2), humeri (6), radii (2), ulnae (1), pelvis (10), femora (22), tibiae (7), fibulae (1), legs (2; bones unspecified), feet and hands (5; bones unspecified). 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. u - 0.7 10-5) and (I The excess death rate due to bone cancer for t > 5 yr is computed from: Effect of Single Skeletal Dose of 1 rad from 224Ra Received by 1,000,000 U.S. White Males at Age 40. When combined with the mean value for diffuse to average concentration of about 0.5,65,77 this indicates that the hot-spot concentration is typically about 7 times the diffuse concentration and that typical hot-spot doses would be roughly an order of magnitude greater than typical diffuse doses. Another difference between the analyses done by Rowland et al. The 9% envelope was obtained by allowing the parameters in the function to vary by 2 standard errors on either side of the mean and emphasizes that the standard errors obtained by least-square fitting underestimate the uncertainty at low doses.