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R A Kleinerman

Publications and source records attributed to R A Kleinerman.

At least 37 records · Page 2Linked to original sources
PubMed1997

Residential exposure to magnetic fields and acute lymphoblastic leukemia in children.

BACKGROUND: Previous studies found associations between childhood leukemia and surrogate indicators of exposure to magnetic fields (the power-line classification since known as "wire coding"), but not between childhood leukemia and measurements of 60-Hz residential magnetic fields. METHODS: We enrolled 638 children with acute lymphoblastic leukemia (ALL) who were under 15 years of age and were registered with the Children's Cancer Group and 620 controls in a study of residential exposure to magnetic fields generated by nearby power lines. In the subjects' current and former homes, data collectors measured magnetic fields for 24 hours in the child's bedroom and for 30 seconds in three or four other rooms and outside the front door. A computer algorithm assigned wire-code categories; based on the distance and configuration of nearby power lines, to the subjects' main residences (for 416 case patients and 416 controls) and to those where the family had lived during the mother's pregnancy with the subject (for 230 case patients and 230 controls). RESULTS: The risk of childhood ALL was not linked to summary time-weighted average residential magnetic-field levels, categorized according to a priori criteria. The odds ratio for ALL was 1.24 (95 percent confidence interval, 0.86 to 1.79) at exposures of 0.200 mu T or greater as compared with less than 0.065 mu T. The risk of ALL was not increased among children whose main residences were in the highest wire-code category (odds ratio as compared with the lowest category, 0.88; 95 percent confidence interval, 0.48 to 1.63). Furthermore, the risk was not significantly associated with either residential magnetic-field levels or the wire codes of the homes mothers resided in when pregnant with the subjects. CONCLUSIONS: Our results provide little evidence that living in homes characterized by high measured time-weighted average magnetic-field levels or by the highest wire-code category increases the risk of ALL in children.

Case-Control Studies↗
PubMed1997

Magnetic field exposure assessment in a case-control study of childhood leukemia.

Epidemiologic evaluation of the relation between magnetic field exposures and cancer depends critically on study design, particularly the methods used for exposure assessment. We incorporated a complex magnetic field exposure assessment protocol into a large incident case-control study of childhood leukemia. We measured residential magnetic fields using a standard protocol in current and former homes of 638 cases and 620 controls and determined wire codes for 414 case-control pairs. We chose a time-weighted average of magnetic field measurements in each eligible home, weighted by the time the subject lived in each home as the main exposure metric for each subject. We found that 24-hour bedroom magnetic field measurements adequately characterize children's residential exposure and that measuring other rooms contributes only slightly to the estimate of average residential exposure to magnetic fields. Front door measured fields provide useful exposure information when interior measurements are missing. If feasible, measuring multiple homes in which the subject has resided is preferable to measuring a single home. A similar distribution of wire codes for controls agreeing or refusing to participate in our study implies that risk estimates derived from wire code data will not be influenced by response bias.

Adolescent↗
PubMed1996

Childhood exposure to magnetic fields: residential area measurements compared to personal dosimetry.

We examined the relation between area measurements of residential magnetic fields and personal dosimetry measurements among 64 control children age 2-14 years from the National Cancer Institute-Children's Cancer Group's nine-state case-control study of childhood leukemia. During a typical weekday, an activity diary was completed, and a 24-hour measurement was obtained in each child's bedroom. According to the activity diaries, children spent more than 40% of the 24 hours in their bedrooms, and 68% of their time at home. We found that at-home personal dosimetry levels were highly correlated with total personal dosimetry levels in children under 9 years (Spearman correlation coefficient, R = 0.94), whereas the correlation was lower in older children (R = 0.59). For all children combined, bedroom 24-hour measurements correlated well with at-home personal dosimetry levels (R = 0.76). The 24-hour bedroom measurement was a useful predictor of both at-home and total personal dosimetry measurements. Particularly for younger children, our data suggest that in-home area measurements predict both current residential and current total magnetic field exposures. This information will be valuable for assessing the validity of exposure assessment in previous and ongoing studies and for developing measurement protocols for future studies.

Adolescent↗
PubMed1995

Second primary cancer after treatment for cervical cancer. An international cancer registries study.

BACKGROUND: The pattern of second cancers after treatment for cervical cancer provides important information on the risk of radiation-induced malignancies. Large numbers of women survive many years and can be studied for late effects. METHODS: Incident second cancers in 86,193 patients with cervical cancer reported to 13 population-based cancer registries in 5 countries were evaluated to estimate the risk of second cancer among very long term survivors. RESULTS: Overall, 7543 second cancers were observed versus 6015 cancers expected based on population rates (observed/expected = 1.2). Lung cancer accounted for nearly half of the excess cancers. Among the 49,828 women treated with radiation, 3750 survived 30 or more years and a two-fold risk of cancers of heavily irradiated organs was seen. Most of the excess cancers were of the rectum, vagina, vulva, ovary, and bladder. Patterns of risk over time since treatment were consistent with a radiation etiology. Significant increases of nonchronic lymphocytic leukemia and cancers of the bone and kidney were also linked to radiotherapy. Women treated surgically were also at significant risk of second cancers, in all likelihood related to cigarette smoking and risk factors similar to those of cervical cancer. CONCLUSIONS: Curative therapy for cervical cancer results in large numbers of long term survivors who develop second cancers very late in life. Radiation is an important cause of this increase and there is no evidence that risk returns to normal levels.

Europe↗
PubMed1994

Cancer following radiotherapy for peptic ulcer.

BACKGROUND: Radiotherapy for peptic ulcer was used between 1937 and 1965 to control excessive gastric acid secretions (mean dose, 14.8 Gy). Patients with this benign condition live many years after treatment and are at risk for late effects. PURPOSE: Our purpose was to investigate the risk of death from cancer following radiotherapy for peptic ulcer. METHODS: A mortality study was conducted of 3609 patients with peptic ulcer; 1831 were treated with radiation and 1778 were treated by other means. Extensive methods were used to trace patients. Radiation doses to specific organs were reconstructed from the original radiotherapy records. RESULTS: Nearly 70% of patients were found to have died. The average period of observation was 21.5 years (maximum 51 years). Compared with the general population, patients treated with or without radiation were at significantly increased risk of dying of cancer and non-malignant diseases of the digestive system. Risk of death due to heart disease was slightly higher following radiotherapy. Cancers of the stomach, pancreas, lung, and prostate were increased in both irradiated and nonirradiated patients. Radiotherapy was linked to significantly high relative risks (RRs) for all cancers combined (RR = 1.53; 95% confidence interval [CI] = 1.3-1.8), for cancers of the stomach (RR = 2.77; 95% CI = 1.6-4.8), pancreas (RR = 1.87; 95% CI = 1.0-3.4), and lung (RR = 1.70; 95% CI = 1.2-2.4), and for leukemia (RR = 3.28; 95% CI = 1.0-10.6). Radiation combined with surgery, or given to treat gastric ulcer, appeared to increase the risk of stomach cancer 10-fold, which was greater than the sum of individual effects. Patients with gastric ulcers were at higher risk for stomach cancer than patients with duodenal ulcers. CONCLUSIONS: Patients with peptic ulcer are at increased risk of dying of cancer, related in part to lifestyle factors and treatment. Radiotherapy and surgery together appear to induce carcinogenic processes that greatly enhance the development of stomach cancer. The risk of radiation-induced stomach cancer was 0.25 extra deaths per 10,000 persons per year per Gy, somewhat lower than reported in other studies. High-dose radiation may have increased the risk of pancreatic cancer, a condition rarely found elevated in irradiated populations, but misclassified death notices may have contributed to the excess. Cancer mortality remained high for up to 50 years, indicating that radiation damage may persist to the end of life.

Aged↗
PubMed1994

Chromosome aberrations in lymphocytes from women irradiated for benign and malignant gynecological disease.

Excess leukemias have occurred after partial-body radiotherapy for cervical cancer and benign gynecological disease (BGD). However, the level of risk is nearly the same in both groups, about twofold, despite a tenfold difference in average dose to active bone marrow (8 Gy vs 0.7 Gy, respectively). High-dose cell killing has been postulated as one explanation for this apparent inconsistency. To examine whether chromosome aberration rates observed in lymphocytes many years after exposure might serve as population markers of cancer risk, blood samples were taken from 60 women treated for BGD (34 with radiation) and cytogenetic data compared with previous results from 96 women irradiated for cervical cancer. Remarkably, the rate of stable aberrations, which reflects nonlethal damage in surviving stem cells, was only slightly higher among the cancer patients. Thus the lower-dose regimens to treat benign disorders resulted in much higher aberration yields per unit dose than those for cervical cancer. Assuming that the fraction of cytogenetically aberrant stem cells that survive radiotherapy contributes to the leukemogenic process, these data are then consistent with the epidemiological observations of comparable overall leukemia risks seen in these two irradiated populations. Accordingly, for patient populations given partial-body radiotherapy, stable aberrations at a long time after exposure appear to serve as biomarkers of effective risk rather than as biomarkers of radiation dose received.

Aged↗
PubMed1993

Leukemia, lymphoma, and multiple myeloma after pelvic radiotherapy for benign disease.

The relationship between exposure to sparsely ionizing radiation and mortality due to cancers of hematopoietic and lymphopoietic tissues was studied among 12,955 women treated for benign gynecological disorders at any of 17 hospitals in New England or New York State and followed for an average of 25 years; 9770 women were treated by radiation (intracavitary 226Ra, external-beam X rays), while 3185 were treated by other methods, including curettage, surgery, and hormones. The average age at treatment was 46.5 years, and the mean dose to active bone marrow among irradiated women was 119 cGy. Forty deaths due to acute, myelocytic, or monocytic leukemia were observed among irradiated women. This number was 70% higher than expected based on U.S. mortality rates [standardized mortality ratio (SMR) = 1.7; 90% confidence interval (CI) 1.3-2.3]. A deficit was recorded among nonirradiated women, based on three observed deaths (SMR = 0.5; 90% CI 0.1-1.2). A well-defined gradient in the SMR with dose among exposed women was not detected. The SMR was highest within 5 years after irradiation but remained elevated even after 30 years. The temporal pattern differed by subtype of leukemia: excess mortality due to chronic myelocytic leukemia occurred almost exclusively within the first 15 years, whereas the SMR for acute leukemia, though also elevated, varied little over time. Cancers of lymphoreticular tissue occurred more often than expected based on U.S. mortality rates, but not appreciably differently for irradiated and nonirradiated women. There was little or no evidence of effects attributable to radiotherapy for chronic lymphocytic leukemia [relative risk (RR) = 1.1; 90% CI 0.5-3.0], Hodgkin's disease (RR = 0.9; 90% CI 0.3-3.2), non-Hodgkin's lymphoma (RR = 0.9; 90% CI 0.6-1.6), or multiple myeloma (RR = 0.6; 90% CI 0.3-1.4). These results corroborate previous findings indicating that acute and myelocytic leukemias are the most prominent malignancies after exposure to sparsely ionizing radiation, occurring in excess shortly after irradiation, and that lymphomas are either not caused by radiation or are induced only rarely.

Bone Marrow↗
PubMed1991

Familial nonmedullary thyroid cancer.

A 5-fold excess risk of nonmedullary thyroid cancer among close relatives of affected patients was detected in a population-based case-control study of thyroid cancer in Connecticut. The 2 familial cases with early onset and multiple foci suggest genetic susceptibility, whereas the 2 cases with late onset may be related to a common environmental exposure.

Adult↗
PubMed1990

Cancer mortality following radium treatment for uterine bleeding.

Cancer mortality in relation to radiation dose was evaluated among 4153 women treated with intrauterine radium (226Ra) capsules for benign gynecologic bleeding disorders between 1925 and 1965. Average follow up was 26.5 years (maximum = 59.9 years). Overall, 2763 deaths were observed versus 2687 expected based on U.S. mortality rates [standardized mortality ratio (SMR) = 1.03]. Deaths due to cancer, however, were increased (SMR = 1.30), especially cancers of organs close to the radiation source. For organs receiving greater than 5 Gy, excess mortality of 100 to 110% was noted for cancers of the uterus and bladder 10 or more years following irradiation, while a deficit was seen for cancer of the cervix, one of the few malignancies not previously shown to be caused by ionizing radiation. Part of the excess of uterine cancer, however, may have been due to the underlying gynecologic disorders being treated. Among cancers of organs receiving average or local doses of 1 to 4 Gy, excesses of 30 to 100% were found for leukemia and cancers of the colon and genital organs other than uterus; no excess was seen for rectal or bone cancer. Among organs typically receiving 0.1 to 0.3 Gy, a deficit was recorded for cancers of the liver, gall bladder, and bile ducts combined, death due to stomach cancer occurred at close to the expected rate, a 30% excess was noted for kidney cancer (based on eight deaths), and there was a 60% excess of pancreatic cancer among 10-year survivors, but little evidence of dose-response. Estimates of the excess relative risk per Gray were 0.006 for uterus, 0.4 for other genital organs, 0.5 for colon, 0.2 for bladder, and 1.9 for leukemia. Contrary to findings for other populations treated by pelvic irradiation, a deficit of breast cancer was not observed (SMR = 1.0). Dose to the ovaries (median, 2.3 Gy) may have been insufficient to protect against breast cancer. For organs receiving greater than 1 Gy, cancer mortality remained elevated for more than 30 years, supporting the notion that radiation damage persists for many years after exposure.

Adolescent↗
PubMed1990

Leukemia following radiotherapy for uterine bleeding.

Mortality due to leukemia among 4483 women treated with radiation to control uterine bleeding between 1925 and 1965 was twice as high as expected based on U.S. population rates (standardized mortality ratio (SMR) = 2.0; 95% confidence interval (CI): 1.4 to 2.8). Women were followed for an average of 26.4 years. Relative risk was highest 2 to 5 years after treatment (SMR = 8.1) and among women over 55 years at irradiation (SMR = 5.8). The usual method of treatment was intrauterine radium. Average radiation dose to active bone marrow was estimated on the basis of original radiotherapy records (median, 53 cGy). A linear dose-response model provided an adequate fit to the data. The average excess relative risk was 1.9% per cGy (95% CI: 0.8 to 3.2), and the average absolute risk was 2.6 excess leukemia deaths per million women per year per cGy (95% CI: 0.9 to 4.8). Chronic myeloid leukemia predominated during the first 15 years following exposure, whereas acute leukemias and chronic lymphatic leukemia were most common thereafter. The radiation doses experienced during treatment of benign gynecologic disease appear to result in greater leukemia risk per cGy average marrow dose than the considerably higher doses used to treat malignant disease, perhaps because of a decreased likelihood of killing potentially leukemic cells.

Adolescent↗
PubMed1990

Chromosome aberrations in relation to radiation dose following partial-body exposures in three populations.

Structural chromosome aberrations were evaluated in peripheral blood samples obtained from three populations exposed to partial-body irradiation. These included 143 persons who received radiotherapy for enlarged thymus glands during infancy and 50 sibling controls; 79 persons irradiated for enlarged tonsils and 81 persons surgically treated for the same condition during childhood; and 77 women frequently exposed as young adults to fluoroscopic chest X rays during lung collapse treatment for tuberculosis (TB) and 66 women of similar ages treated for TB with other therapies. Radiation exposures occurred 30 and more years before blood was drawn. Doses to active bone marrow averaged over the entire body were 21, 6, and 14 cGy for the exposed thymic, tonsil, and TB subjects, respectively. Two hundred metaphases were scored for each subject, and the frequencies of symmetrical (stable) and asymmetrical (unstable) chromosome aberrations were quantified in 97,200 metaphases. Cells with stable aberrations were detected with greater frequency in the irradiated subjects compared with nonirradiated subjects in all three populations, and an overall test for an association between stable aberrations and partial-body ionizing radiation was highly significant (P less than 0.001). We found no evidence that radiation-induced aberrations varied by age at exposure. These data show that exposure of children or young adults to partial-body fractionated radiation can result in detectable increased frequencies of stable chromosome aberrations in circulating lymphocytes 30 years later, and that these aberrations appear to be informative as biological markers of population exposure.

Chromosome Aberrations↗
PubMed1989

Radiation dose and breast cancer risk in patients treated for cancer of the cervix.

The relationship between breast cancer and radiation treatment for cervical cancer was evaluated in an international study of 953 women who subsequently developed breast cancer and 1,806 matched controls. Radiation doses to the breast (average 0.31 Gy) and ovaries (average 32 Gy) were reconstructed for exposed subjects on the basis of their original radiotherapy records. Overall, 88% of the breast cancer cases and 89% of the controls received radiation treatment [relative risk (RR) = 0.88; 95% confidence interval (CI) = 0.7-1.2]. Among women with intact ovaries (561 cases, 1,037 controls), radiotherapy was linked to a significant 35% reduction in breast cancer risk, attributable in all likelihood to the cessation of ovarian function. Ovarian doses of 6 Gy were sufficient to reduce breast cancer risk but larger doses did not reduce risk further. This saturation-type response is probably due to the killing of a critical number of ovarian cells. Cervical cancer patients without ovaries (145 cases, 284 controls) were analyzed separately because such women are at especially low natural risk for breast cancer development. In theory, any effect of low-dose breast exposure, received incidentally during treatment for cervical cancer, should be more readily detectable. Among women without ovaries, there was a slight increase in breast cancer risk (RR = 1.07; 95% CI = 0.6-2.0), and a suggestion of a dose response with the RR being 1.0, 0.7, 1.5 and 3.1 for breast doses of 0, 0.01-0.24, 0.25-0.49 and 0.50+ Gy, respectively. However, this trend of increasing RR was not statistically significant. If low-dose radiation increases the risk of breast cancer among women over age 40 years, it appears that the risk is much lower than would be predicted from studies of younger women exposed to higher doses.

Adult↗
PubMed1989

Chromosome aberrations in peripheral lymphocytes and radiation dose to active bone marrow in patients treated for cancer of the cervix.

An international study of cervical cancer patients reported a doubling of the risk for leukemia following radiotherapy. To evaluate the extent of residual chromosome damage in circulating T-cell lymphocytes in this population, approximately 200 metaphases were examined from each of 96 irradiated and 26 nonirradiated cervical cancer patients treated more than 17 years ago (average 23 years). Radiation dose averaged over the total red bone marrow was estimated to be 8.1 Gy. The type and frequency of stable and unstable chromosome aberrations were quantified in 24,117 metaphases. Unstable aberrations did not differ significantly between irradiated and nonirradiated patients (P greater than 0.5). Stable aberrations (i.e., translocations, inversions, or chromosomes with deleted segments), however, were significantly higher among irradiated (2.8 per 100 cells) compared to nonirradiated (0.7 per 100 cells) women (P less than 10(4). The frequency of these stable aberrations was found to increase significantly with increasing dose to the bone marrow. These data indicate that a direct relationship between radiation dose and extent of damage to somatic cells persists in populations and can be detected many years after partial-body radiation exposure. The stable aberration rate in irradiated cervical cancer patients was 50 to 75% lower than those observed 25 years or more after radiation exposure in atomic bomb survivors and in ankylosing spondylitis patients treated with radiotherapy. The average marrow dose was only 1 Gy in the examined atomic bomb survivors and 3.5 Gy in the ankylosing spondylitis patients. It appears, then, that a very high dose delivered to the pelvic cavity in fractionated doses resulted in far fewer persistent stable aberrations than lower doses delivered either in acute whole-body exposure or in fractionated doses to the spinal column and sacroiliac joints. The higher radiation dose and the concentration of that dose in a smaller area of the body appear to be responsible for the lower rate of persistent aberrations observed in cervical cancer patients.

Bone Marrow↗
PubMed1988

Radiation dose and second cancer risk in patients treated for cancer of the cervix.

The risk of cancer associated with a broad range of organ doses was estimated in an international study of women with cervical cancer. Among 150,000 patients reported to one of 19 population-based cancer registries or treated in any of 20 oncology clinics, 4188 women with second cancers and 6880 matched controls were selected for detailed study. Radiation doses for selected organs were reconstructed for each patient on the basis of her original radiotherapy records. Very high doses, on the order of several hundred gray, were found to increase the risk of cancers of the bladder [relative risk (RR) = 4.0], rectum (RR = 1.8), vagina (RR = 2.7), and possibly bone (RR = 1.3), uterine corpus (RR = 1.3), cecum (RR = 1.5), and non-Hodgkin's lymphoma (RR = 2.5). For all female genital cancers taken together, a sharp dose-response gradient was observed, reaching fivefold for doses more than 150 Gy. Several gray increased the risk of stomach cancer (RR = 2.1) and leukemia (RR = 2.0). Although cancer of the pancreas was elevated, there was no evidence of a dose-dependent risk. Cancer of the kidney was significantly increased among 15-year survivors. A nonsignificant twofold risk of radiogenic thyroid cancer was observed following an average dose of only 0.11 Gy. Breast cancer was not increased overall, despite an average dose of 0.31 Gy and 953 cases available for evaluation (RR = 0.9); there was, however, a weak suggestion of a dose response among women whose ovaries had been surgically removed. Doses greater than 6 Gy to the ovaries reduced breast cancer risk by 44%. A significant deficit of ovarian cancer was observed within 5 years of radiotherapy; in contrast, a dose response was suggested among 10-year survivors. Radiation was not found to increase the overall risk of cancers of the small intestine, colon, ovary, vulva, connective tissue, breast, Hodgkin's disease, multiple myeloma, or chronic lymphocytic leukemia. For most cancers associated with radiation, risks were highest among long-term survivors and appeared concentrated among women irradiated at relatively younger ages.

Female↗
PubMed1987

A population-based case-control study of thyroid cancer.

A population-based case-control interview study of thyroid cancer (159 cases and 285 controls) was conducted in Connecticut. Prior radiotherapy to the head or neck was reported by 12% of the cases and 4% of the controls [odds ratio (OR) = 2.8; 95% confidence interval = 1.2-6.9]. Risk was inversely related to age at irradiation and was highest among children exposed under age 10. Few persons born after 1945 received prior radiotherapy, consistent with the declining use of radiation to treat benign conditions in the 1950's. Among females the radiogenic risk appeared to be potentiated by the number of subsequent live-births. Other significant risk factors included a history of benign thyroid nodules (OR = 33) or goiter (OR = 5.6). Miscarriage and multiparity increased risk but only among women who developed thyroid cancer before age 35 years. Consumption of shellfish (a rich source of iodine) seemed to increase the risk of follicular thyroid cancer, whereas consumption of goitrogen-containing vegetables appeared to reduce risk of total thyroid cancer, possibly because of their cruciferous nature. A significantly low risk was observed among persons of English descent, whereas Italian ancestry appeared to increase risk. No significant associations were found with a number of suspected risk factors: diagnostic x-rays, radioactive isotope scans, occupational radiation exposure, tonsillectomy, Jewish ethnicity, alcohol intake, cigarette smoking, oral contraceptives, lactation suppressants, menopausal estrogens, most other common medications, and water source. New associations were suggested for obesity among females (OR = 1.5), surgically treated benign breast disease (OR = 1.6), use of spironolactone (OR = 4.3) or vitamin D supplements (OR = 1.8), and a family history of thyroid cancer (OR = 5.2). About 9% of the incident thyroid cancers could be attributed to prior head and neck irradiation, 4% to goiter, and 17% to thyroid nodular disease, leaving the etiology of most thyroid cancers yet to be explained.

Adult↗
PubMed1987

Radiation dose and leukemia risk in patients treated for cancer of the cervix.

To quantify the risk of radiation-induced leukemia and provide further information on the nature of the relationship between dose and response, a case-control study was undertaken in a cohort of over 150,000 women with invasive cancer of the uterine cervix. The cases either were reported to one of 17 population-based cancer registries or were treated in any of 16 oncologic clinics in Canada, Europe, and the United States. Four controls were individually matched to each of 195 cases of leukemia on the basis of age and calendar year when diagnosed with cervical cancer and survival time. Leukemia diagnoses were verified by one hematologist. Radiation dose to active bone marrow was estimated by medical physicists on the basis of the original radiotherapy records of study subjects. The risk of chronic lymphocytic leukemia, one of the few malignancies without evidence for an association with ionizing radiation, was not increased [relative risk (RR) = 1.03; n = 52]. However, for all other forms of leukemia taken together (n = 143), a twofold risk was evident (RR = 2.0; 90% confidence interval = 1.0-4.2). Risk increased with increasing radiation dose until average doses of about 400 rad (4 Gy) were reached and then decreased at higher doses. This pattern is consistent with experimental data for which the down-turn in risk at high doses has been interpreted as due to killing of potentially leukemic cells. The dose-response information was modeled with various RR functions, accounting for the nonhomogeneous distribution of radiation dose during radiotherapy. The local radiation doses to each of 14 bone marrow compartments for each patient were incorporated in the models, and the corresponding risks were summed. A good fit to the observed data was obtained with a linear-exponential function, which included a positive linear induction term and a negative exponential term. The estimate of the excess RR per rad was 0.9%, and the estimated RR at 100 rad (1 Gy) was 1.7. The model proposed in this study of risk proportional to mass exposed and of risk to an individual given by the sum of incremental risks to anatomic sites appears to be applicable to a wide range of dose distributions. Furthermore, the pattern of leukemia incidence associated with different levels of radiation dose is consistent with a model postulating increasing risk with increasing exposure, modified at high doses by increased frequency of cell death, which reduces risk.

Adult↗