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. Also, mortality statistics as they now exist include the effect of environmental exposures to radium isotopes. If it is inhaled or swallowed, radium is dangerous because there is no shielding inside the body. Knowing the death rate as a function of time for each starting age then allows the impact of radiation exposure to be calculated for each age group and to be summed for the whole population. For comparison with the values given previously for juveniles and adults separately, this is 2.0% incidence per 100 rad, which is somewhat higher than either of the previous values. When examined in this fashion, questions arise. 4, Radium. An internally deposited radioactive element may concentrate in, and thus irradiate, certain organs more than others. 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. Littman et al.31 have presented a list of symptoms in tabular form gleaned from a study of the medical records of 32 subjects who developed carcinoma of the paranasal sinuses or mastoid air cells following exposure to 226,228Ra. Error bars on the points vary in size, and are all less than about 6% cumulative incidence (Figure 4-4). A total of almost 908,000 residents constituted the exposed population; the mean level of radium in their water was 4.7 pCi/liter. Finkel, A. J., C. E. Miller, and R. J. Hasterlik. Because CLL is not considered to be induced by radiation, the latter case was assumed to be unrelated to the radium exposure. The individual cells range from 0.1 to more than 1 cm across and are too numerous to be counted. For t less than 5 yr, M(D,t) is essentially 0 because of the minimum latent period. 's analysis, the 228Ra dose was given a weight 1.5 times that of 226Ra. This population has now been followed for 34 yr; the average follow-up for the exposed group is about 16 yr. A total of 433 members of the exposed group have died, leaving more than 1,000 still alive. It later appears in the urine and feces, with the majority of excretion occurring by the fecal route. s is the average skeletal dose in gray (1 Gy is 100 rad). s is 226Ra skeletal dose. 1978. The results of this series of studies of bone sarcoma incidence among 224Ra-exposed subjects extending over a period of 15 yr underscore the importance of repeated scrutiny of unique sets of data. The risk envelopes defined by these analyses are not unique. Following entry into the circulatory system from the gut or lungs, radium is quickly distributed to body tissues, and a rapid decrease in its content in blood occurs. These results are in marked contrast to those of Kolenkow30 and Littman et al.31 Under Schlenker's73 assumptions, the airspace is the predominant source of dose, with the exception noted, whether or not the airspace is ventilated. Ventilation of the mastoid air cells occurs through the eustachian tube which normally allows little air to move. Hindmarsh, M., M. Owen, and J. Vaughan. This change had no effect on the fitted value of , the free parameter in the linear dose-response function. To circumvent this problem, two strategies have been developed: (1) classification of the cases according to their epidemiological suitability, on a scale of 1 to 5, with 5 representing the least suitable and therefore the most likely to cause bias and 1 representing the most suitable and therefore the least likely to cause bias; and (2) definition of subgroups of the whole population according to objective criteria presumably unrelated to tumor risk, for example, by year of first exposure and type of exposure. Correspondingly, relatively simple and complete dose-response functions have been developed that permit numerical estimates of the lifetime risk, that is, about 2 10-2/person-Gy for bone sarcoma following well-protracted exposure. 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. Thus, most data analyses have presented cancer-risk information in terms of dose-response graphs or functions in which the dependent variable represents some measure of risk and the independent variable represents some measure of insult. For 31 of the tumors, estimates of skeletal dose can and have been made. Carcinomas of the Paranasal Sinuses and Mastoid Air Cells among Persons Exposed to 226,228Ra and Currently Under Study at Argonne National Laboratory. Otherwise, the retention in bone is estimated by models. At D In the latter analysis,69 the only acceptable fit based on year of entry into the study is: where I and D In people with radium burdens of many years' duration, only 2% of the excreted radium exits through the kidneys. . The remaining two cases were aplastic anemias; these latter two cases and one of the CML cases were not available for study, and hence no measurements of radium content in the workers' bodies were available. Combining this information with results observed with 224Ra may lead to the development of a general model for bone cancer induction due to alpha-particle emitters. The sinus and mastoid carcinomas in persons exposed to. i = 0.5 Ci, the lower boundary of the lowest intake cohort used when fitting functions to the data. Why does radium accumulate in bones?-Radium accumulates in bones because radium essentially masks itself as calcium. For nonstochastic effects, apparent threshold doses vary with health endpoint. 1969. Radium is highly radioactive. 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. A three- or four-inch pipe pulls radon from underneath the house and vents it outside. The upper curve of the 68% envelope is nearly coincident with the upper boundary of the shaded envelope. Recall that the preceding discussion of tumor appearance time and rate of tumor appearance indicated that tumor rate increases with time for some intake bands, verifying a suggestion by Rowland et al.67 made in their analysis of the carcinoma data. The increase of median tumor appearance time with decreasing dose rate strengthens the case for a practical threshold. There were three cases of chronic myeloid leukemia (CML) and one of chronic lymphocytic leukemia (CLL). 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. When the average exposure period is several hundred days, as it was for humans exposed to 226,228Ra, there will be only a minor reduction of hot-spot dose rate because the blood level is maintained at a high average level for the whole period of formation of most hot spots.67 Autoradiographs from radium cases with extended exposures such as those published by Rowland and Marshall65 bear this out and form a sharp contrast to autoradiographs of animal bone following single injection36 on which the model of hot-spot burial was based. 1984. Batsakis, J. G., and J. J. Sciubba. Dose is used here as a generic term for the variety of dosimetric variables that have been used in the presentation of cancer incidence data. However, the change was not so great as to alter the basic conclusion that the data have too little statistical strength to distinguish between various mathematical expressions for the dose-response curve. In the subject with carcinoma, he observed a hot layer of bone beginning about 2 m from the surface and extending inward a distance greater than the alpha-particle range. For animals given a single injection, hot spots probably played a role similar to that played by diffuse radioactivity. The eustachian tube provides ventilation for the middle ear and pneumatized portions of the temporal bone. These estimates are based on retention integrals74 and relative distribution factors40 that originate from retention and dosimetry models. . This emphasizes that there is no unique way to specify the uncertainty in risk at low exposures when the shape of the dose-response curve is unknown. 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. Wick et al.95 reported on another study of Germans exposed to 224Ra. Committee on the Biological Effects of Ionizing Radiations (BEIR). It emits alpha, beta, and gamma radiation. Lloyd and Henning33 described a fibrotic layer adjacent to the endosteal surface and the types and locations of cells within it in a radium-dial painter who had died with fibrosarcoma 58 yr after the cessation of work and who had developed an average skeletal dose of 6,590 rad, roughly the median value among persons who developed radium-induced bone cancer. Based on a suggestion by Muller drawn from his observations of mice, Speiss and Mays86 reanalyzed their 224Ra data in an effort to determine whether there was an association between dose protraction and tumor yield. One of these was panmyelosis, and the other was aplastic anemia; the radium measurements for these two cases showed body contents of 10.5 and 10.7 Ci, respectively. For tumors of known histologic type, 56% are epidermoid, 34% are mucoepidermoid, and 10% are adenocarcinomas. These were plotted against a variety of dose variables, including absorbed dose to the skeleton from 226Ra and 228Ra, pure radium equivalent, and time-weighted absorbed dose, referred to as cumulative rad years. The case for a dose rate or dose-protraction effect rests on the observation of an association of the linear dose-response slope with dose rate in humans and the unequivocal appearance of a dose-protraction effect in mice and rats. The second, which used the deep-well data from the prior study, examined cancer incidence as a function of radium content of the water. Hindmarsh, M., M. Owen, J. Vaughan, L. F. Lamerton, and F. W. Spiers. This is the first report of an explicit test of linearity that has resulted in rejection. Figure 4-5 shows the results of this analysis, and Table 4-3 gives the equations for the envelope boundaries. In an additional group of 37 patients who were treated with radium by their personal physicians, two blood dyscrasias were found. These relationships have important dosimetric implications. Subnormal excretion rate can be linked with the apparent subnormal remodeling rates in high-dose radium cases.77.