Cancer mortality and morbidity among plutonium workers at the Sellafield plant of British Nuclear Fuels.
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The mortality of all 14 319 workers employed at the Sellafield plant of British Nuclear Fuels between 1947 and 1975 was studied up to the end of 1992, and cancer incidence was examined from 1971 to 1986, in relation to their exposures to plutonium and to external radiation. The cancer mortality rate was 5% lower than that of England and Wales and 3% less than that of Cumbria. The significant excesses of deaths from cancer of the pleura and thyroid found in an earlier study persist with further follow-up (14 observed, 4.0 expected for pleura; 6 observed, 2.2 expected for thyroid). All of the deaths from pleural cancer were among radiation workers. For neither site was there a significant association between the risk of the cancer and accumulated radiation dose. There were significant deficits of deaths from cancers of mouth and pharynx, liver and gall bladder, and larynx and leukaemia when compared with the national rates. Among all radiation workers, there was a significant positive association between accumulated external radiation dose and mortality from cancers of ill-defined and secondary sites (10-year lag, P = 0.04), leukaemia (no lag, P = 0.03; 2-year lag, P = 0.05), multiple myeloma (20-year lag, P = 0.02), all lymphatic and haematopoietic cancers (20-year lag, P= 0.03) and all causes of death combined (20-year lag, P= 0.008). Among plutonium workers, there were significant excesses of deaths from cancer of the breast (6 observed, 2.6 expected) and ill-defined and secondary cancers (29 observed, 20.1 expected). No significant positive trends were observed between the risk of deaths from cancers of any specific site, or all cancers combined, and cumulative plutonium and external radiation doses. For no cancer site was there a significant excess of cancer registrations compared with rates for England and Wales. Analysis of trends in cancer incidence showed significant increases in risk with cumulative plutonium plus external radiation doses for all lymphatic and haematopoietic neoplasms for 0-, 10- and 20-year lag periods. Taken as a whole, our findings do not suggest that workers at Sellafield who have been exposed to plutonium are at an overall significantly increased risk of cancer compared with other radiation workers. (+info)
Retention, excretion and translocation of 239Pu in rats following inhalation of 239PuO2 calcined at 1150 and 400 degrees C.
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Wistar rats inhaled 239PuO2 particles prepared by the calcination of 239Pu hydroxide at 1150 and 400 degrees C. Lung retention, fecal and urinary excretion, and translocation of 239Pu were compared between the two calcination temperatures. The clearance of 239Pu from the lungs was significantly faster in the rats exposed to 239PuO2 calcined at 400 degrees C (low-temperature group) than those exposed to 239PuO2 calcined at 1150 degrees C (high-temperature group). Both the fecal excretion of 239Pu and the ratio of fecal excretion to urinary excretion was greater in the low-temperature group than in high-temperature group. The amounts of 239Pu translocated from the lungs to the other organs were very small. Even in the liver, which accumulated the largest amount of 239Pu except for the lungs, only 0.13-0.20% of the initial lung burden was retained 1 year after inhalation. The amount of 239Pu deposited in the liver was greater in the high-temperature group than in the low-temperature group both at 1 month and 1 year after the inhalation. These findings clearly suggest that the lung retention of 239Pu in rats is significantly affected by the calcination temperature of 239PuO2. (+info)
Radiographic features of bone in several strains of laboratory mice and of their tumours induced by bone-seeking radionuclides.
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The natural radiographic appearance of the various bones of the skeleton are described for several strains of laboratory mice. The Harwell substrains of CBA, A and 101 are generally similar and become osteoporotic on ageing. Harwell C57BL have similar, but more delicately chiseled, bones. Harwell C3H mice have bones with stouter cortices and may show osteosclerosis on ageing. CF1 females (donated by Dr M. Finkel) showed osteosclerosis and osteophytic outgrowths when aged. NMRI mice (donated by Dr A. Luz) appeared larger than the pure-strain Harwell mice. In general, mouse bones are simple tubular structures with an ivory cortex and a marrow cavity. Cancellous trabecular bone is scanty, even in vertebrae, flat bones and the metaphyses of long bones. Bone-seeking radionuclides administered to mice lead to skeletal tumours: (a) osteosarcomata, which are commonly radio-opaque to a variable degree owing to calcified tumour bone, but which may be osteolytic, (b) primitive mesenchymal (angio-) sarcomata which are non-osteogenic and osteolytic, (c) fibrosarcomata--which also are osteolytic--and to local or general lymphomata from irradiation of parental cells in bone marrow, but no special radiological features have been found associated with these last-named tumours. (+info)
Risks to the public from historical releases of radionuclides and chemicals at the Rocky Flats Environmental Technology Site.
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This paper summarizes the methods and results of estimating risks of cancer incidence resulting from plutonium, carbon tetrachloride, and beryllium releases from operations at the Rocky Flats Environmental Technology Site, near Denver, Colorado, from 1953 through 1989. The key findings show that people who lived near the facility were exposed to plutonium mainly through inhalation during routine operations, from a major fire in 1957, and from plutonium resuspended from contaminated soil from an outdoor drum storage area, called the 903 Area. Results were presented for five exposure scenarios that were location-independent. Individuals described by the laborer scenario received the highest risk of all scenarios considered. Upper bound (95th percentile) incremental lifetime cancer incidence risks for the laborer scenario were in about the 10(-4) range (1 chance in 10,000) for developing cancer from Rocky Flats plutonium releases during a lifetime. At the 5th percentile level, the maximum cancer risk was about 10(-7) (1 chance in 10 million) for developing cancer during a lifetime. Estimated cancer risks at the 95th percentile level are within the range of for acceptable risks established by the US Environmental Protection Agency of 10(-6) to 10(-4). Carbon tetrachloride was found to be the chemical that presented the highest risk to the public. The 5th and 95th percentile risk values for exposure to carbon tetrachloride were 9.2x10(-7) and 2.5x10(-5), respectively. (+info)
Influence of various factors on individual radiation exposure from the Chernobyl disaster.
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BACKGROUND: The explosion at the Chernobyl Nuclear Power Plant was one of the greatest known nuclear disasters of the 20th century. To reduce individual exposure to ionizing radiation the Soviet Union government introduced a number of counter-measures. This article presents a description of how historical events conspired to disrupt these efforts and affect residents in exposed areas. METHODS: This study employed an extensive review of data on radionuclide deposition, contamination patterns and lifestyle characteristics. Data were obtained from the Ukraine Ministry of Health and the Ukraine Research Center for Radiation Medicine. RESULTS: Data are presented on annual contamination rates in selected locales as well as data on local food consumption patterns. Historical factors including economic and political circumstances are also highlighted. Results show the diminution of individual doses between 1987 and 1991 and then an increase between 1991 and 1994 and the relationship between this increase and changes in the lifestyle of the local population. CONCLUSION: A number of factors played direct and indirect roles in contributing to the populace's cumulative radiation exposure. Future post-contamination studies need to consider these factors when estimating individual exposures. (+info)
Immunohistochemical study on cellular origins of rat lung tumors induced by inhalation exposures to plutonium dioxide aerosols as compared to those by X-ray irradiation.
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Immunohistochemical examinations were performed on rat pulmonary tumors induced by inhalation exposures to 239PuO2 aerosols, or by X-ray-irradiation to identify and compare cellular origins or, in turn, target cells at risk for radiation carcinogenesis. Both plutonium-induced and X-ray-induced pulmonary tumors appeared to occur from the lower respiratory tract epithelium through bronchioles into alveoli, and were histopathologically diagnosed as adenoma, adenocarcinoma, adenosquamous carcinoma, and squamous cell carcinoma. Immunohistochemical staining of neoplastic lesions using rabbit polyclonal antibodies to rat surfactant apoprotein A specific for alveolar type II pneumocytes, and Clara cell antigen specific for nonciliated bronchiolar Clara cells, showed that most of the adenomatous and adenocarcinomatous lesions from plutonium-exposed or X-irradiated rats were positive for either or both antigens, while, in contrast, adenosquamous and squamous lesions were mostly negative for both antigens. Even though there were some differences in the proportions and distributions of immunoreactive cells between plutonium- and X-ray-induced tumors and among neoplastic lesions, the results indicate that radiation-induced pulmonary adenomas and adenocarcinomas mostly originate from either alveolar type II pneumocytes or bronchiolar Clara cells, while adenosquamous and squamous carcinomas may be derived from the other epithelial cell components, or might have lost specific antigenicity during their transforming differentiation. (+info)
The relationship between internally deposited alpha-particle radiation and subsite-specific liver cancer and liver cirrhosis: an analysis of published data.
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Chronic exposure to high LET radiation has been shown to cause liver cancer in humans based on studies of patients who received Thorotrast, a colloidal suspension of thorium dioxide formerly used as a radiological contrast agent, and on studies of Russian nuclear weapons workers exposed to internally ingested plutonium. Risk estimates for these exposures and specific subtypes of liver cancer have not been previously reported. Combining published data with tumor registry data pertinent to the Thorotrast cohorts in Germany, Denmark, Portugal, and Japan and to Russian workers, we generally found significantly elevated risks of three major histologic types of liver tumors: hepatocellular carcinoma (HCC), cholangiocarcinoma (CC), and hemangiosarcoma (HS) for Thorotrast exposures. In contrast, HS was the only liver tumor significantly associated with the lower alpha-particle doses experienced by the Russian workers. Excess cases per 1,000 persons exposed to Thorotrast were similar for the three liver cancer subtypes but lower for plutonium exposure. Odds ratios (OR) of HS and CC for Thorotrast were from 26 to 789 and from 1 to 31 times higher than those for HCC, respectively. ORs of liver cirrhosis for Thorotrast exposure ranged from 2.7 (95% confidence interval (CI): 2.2-3.4) to 6.7 (5.1-8.7). (+info)
Past exposure to densely ionizing radiation leaves a unique permanent signature in the genome.
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Speculation has long surrounded the question of whether past exposure to ionizing radiation leaves a unique permanent signature in the genome. Intrachromosomal rearrangements or deletions are produced much more efficiently by densely ionizing radiation than by chemical mutagens, x-rays, or endogenous aging processes. Until recently, such stable intrachromosomal aberrations have been very hard to detect, but a new chromosome band painting technique has made their detection practical. We report the detection and quantification of stable intrachromosomal aberrations in lymphocytes of healthy former nuclear-weapons workers who were exposed to plutonium many years ago. Even many years after occupational exposure, more than half the blood cells of the healthy plutonium workers contain large (>6 Mb) intrachromosomal rearrangements. The yield of these aberrations was highly correlated with plutonium dose to the bone marrow. The control groups contained very few such intrachromosomal aberrations. Quantification of this large-scale chromosomal damage in human populations exposed many years earlier will lead to new insights into the mechanisms and risks of cytogenetic damage. (+info)