Twenty-six white male workers who did the original plutonium research and development work at Los Alamos have been examined periodically over the past 50 y to identify possible health effects from internal plutonium depositions. Their effective doses range from 0.1 to 7.2 Sv with a median value of 1.25 Sv. As of the end of 1994, 7 individuals have died compared with an expected 16 deaths based on mortality rates of U.S. white males in the general population. The standardized mortality ratio (SMR) is 0.43. When compared with 876 unexposed Los Alamos workers of the same period, the plutonium worker's mortality rate was also not elevated (SMR = 0.77). The 19 living persons have diseases and physical changes characteristic of a male population with a median age of 72 y (range = 69 to 86 y). Eight of the twenty-six workers have been diagnosed as having one or more cancers, which is within the expected range. The underlying cause of death in three of the seven deceased persons was from cancer, namely cancer of prostate, lung, and bone. Mortality from all cancers was not statistically elevated. The effective doses from plutonium to these individuals are compared with current radiation protection guidelines.
Twenty-six white male subjects, who worked with plutonium (239Pu) during World War II at Los Alamos, have been given medical examinations periodically over a period of 42 y to identify potential health effects. Inhalation was the primary mode of Pu exposures. The latest examinations, including urine bioassay and in-vivo measurements for radioactivity, were performed in late 1986 and 1987. The average age of the 22 living subjects in 1986 was 66 y. The diseases and physical changes noted in these persons are characteristic of a male population in their 60s. Estimates of individual Pu depositions, including lung burdens, as of 1987 or at time of death range from 52 to 3180 Bq (1.4 to 86 nCi) with a median value of 500 Bq (13.5 nCi). Four persons from the original group had died as of 1987. The causes of death were lung cancer, myocardial infarction, accidental injury, and respiratory failure due to pneumonia/congestive heart failure. Expected deaths based on U.S. death rates of white males, adjusted for age and calendar year, are 9.2 based on U.S. rates (standardized mortality ratio = 0.41). Subsequent to 1987, three additional deaths occurred from atherosclerotic heart disease, lung cancer, and osteogenic sarcoma. The bone sarcoma case is discussed in terms of Pu exposure, the natural incidence of this disease, anatomical location of the tumor, and bone tumors observed in Pu-exposed dogs. Plutonium deposition in this man is estimated to have been below current radiation protection guidelines.
The present paper presents an historical account of th.: Los Alamos Scientific Laboratory's industrial medical experience with exposure of personnel to Observations cover the period from the beginning of the Manhattan Project through 1960. In the early days, exposures were of an acute or semiacute nature. Improved industrial hygiene and engineering methods have changed the problem to one of chronic low-level exposure, largely via inhalation. Consideration of the Laboratory's experience during the past 17 years suggests that the present problem areas are: (1) the diagnosis of body burden under chronic exposure conditions and with little or no specific index of exposure other than a persistent low-level urinary excretion rate, and (2) the choice ofthe critical organ when exposure is largely via chronic low-level inhalation.
Twenty-six male subjects who worked with plutonium during World War I1 under extraordinarily crude conditions have been followed medically for a period of 32 yr. Inhalation was the primary mode of plutonium exposure. Current estimates of the systemic plutonium depositions in these individuals range from 7 to 230nCi. Eleven individuals have depositions greater than 40 nCi, the current maximum permissible body burden for workers. Two individuals in the group have died: one due to myocardial infarction and the other due to injuries sustained in an automobile-pedestrian accident. This mortality rate is about 50% of expected deaths based on United States white male rates. All 24 living subjects were re-examined in the period of 1975-78. No cases of cancer were diagnosed in the group except for two skin cancers that have no history or basis that relate them to plutonium exposure. The diseases and physical changes noted in the group are characteristic of a male population in their 50s and 60s. This study yields no evidence suggesting that adverse health effects have resulted from the 32 yr of exposure to the internally deposited plutonium.
Calculations based on a two-parameter description of a uniformly charged liquid drop are reported. Results include fission-barrier energy and other saddle-point properties. The electrostatic energy of the drop was computed by a novel and highly accurate method. The saddle-point properties and corresponding drop shapes are compared with calculations that use nine parameters. Agreement is best for fissionability parameters greater than 0.70, suggesting that these calculations may provide a few-parameter basis for dynamical calculations of adequate precision at the larger fissionability parameters.
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