Suitsiid ja muud surmapõhjused Eestist pärit Tšernobõli veteranide hulgas 1986–2020: ajakohastatud andmed

Eesti Arst 2023; 102(8):41

Cancer mortality in a Texas county with prior uranium mining and milling activities, 1950-2001

Abstract Uranium was discovered in Karnes County, Texas, in 1954 and the first uranium mill began operating in 1961 near Falls City. Uranium milling and surface and in situ mining continued in Karnes County until the early 1990s. Remediation of uranium tailings ponds was completed in the 1990s. There were three mills and over 40 mines operating in Karnes County over these years and potential exposure to the population was from possible environmental releases into the air and ground water. From time to time concerns have been raised in Karnes County about potential increased cancer risk from these uranium mining and milling activities. To evaluate the possibility of increased cancer deaths associated with these uranium operations, a mortality survey was conducted. The numbers and rates of cancer deaths were determined for Karnes County and for comparison for four 'control' counties in the same region with similar age, race, urbanisation and socioeconomic distributions reported in the 1990 US Census. Comparisons were also made with US and Texas general population rates. Following similar methods to those used by the National Cancer Institute, standardised mortality ratios (SMRs) were computed as the ratio of observed numbers of cancers in the study and control counties compared to the expected number derived from general population rates for the United States. Relative risks (RRs) were computed as the ratios of the SMRs for the study and the control counties. Overall, 1223 cancer deaths occurred in the population residing in Karnes County from 1950 to 2001 compared with 1392 expected based on general population rates for the US. There were 3857 cancer deaths in the four control counties during the same 52 year period compared with 4389 expected. There was no difference between the total cancer mortality rates in 3 Author to whom any correspondence should be addressed. Karnes County and those in the control counties (RR = 1.0; 95% confidence interval 0.9-1.1). There were no significant increases in Karnes County for any cancer when comparisons were made with either the US population, the State of Texas or the control counties. In particular, deaths due to cancers of the lung, bone, liver and kidney were not more frequent in Karnes County than in the control counties. These are the cancers of a priori interest given that uranium might be expected to concentrate more in these tissues than in others. Further, any radium intake would deposit primarily in the bone and radon progeny primarily in the lung. Deaths from all cancers combined also were not increased in Karnes County and the RRs of cancer mortality in Karnes County before and in the early years of operations , shortly after the uranium activities began and in two later time periods (1990)(1991)(1992)(1993)(1994)(1995)(1996)(1997)(1998)(1999)(2000)(2001) were similar, 1.0, 0.9, 1.1 and 1.0, respectively. No unusual patterns of cancer mortality could be seen in Karnes County over a period of 50 years, suggesting that the uranium mining and milling operations had not increased cancer rates among residents

Comprehensive dosimetry for seven exposure sources at the earliest US uranium processing facility

Mallinckrodt Chemical Works (MCW) was the earliest uranium processing facility in the United States, beginning in 1942. The 2,514 workers included in the epidemiologic study were exposed to external gamma radiation, medical x-rays, internal radiation from intakes of pitchblende ore and its extracted radionuclides (mainly uranium isotopes and radium-226), and ambient levels of radon and its progeny [1]

Thyroid nodularity after childhood irradiation for lymphoid hyperplasia: a comparison of questionnaire and clinical findings

Ionizing radiation is a well-established cause of thyroid cancer and modularity, however, important questions relating to the magnitude of the risk following low-dose medical exposures remain unresolved. To address these issues, we conducted a follow-up study of 1590 individuals treated between 1938 and 1969 with X-rays for childhood lymphoid hyperplasia (av. thyroid DOSE = 24 cGy) and 1499 individuals treated with surgery only. Thyroid nodularity was determined from self-administered questionnaires completed by 1195 irradiated and 1063 surgically-treated subjects and from clinical examinations of 602 irradiated and 457 non-irradiated subjects. A much higher relative risk (RR) for radiation-induced thyroid nodules was estimated from the questionnaire than from the clinical examination data, 15.8 and 2.7, respectively. (The corresponding estimates of excess RR per cGy were 64 and 7%). Analysis of the examination data revealed a strong dose-response relationship, similar excess RR/cGy for males and females, and an inverse relationship with age at exposure. Although the thyroid gland is one of the most sensitive organs to the neoplastic effects of radiation, the radiation-induced risk of thyroid nodularity reported from questionnaire studies may over-estimate the true risk.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/28887/1/0000723.pd

The Science of Sungrazers, Sunskirters, and Other Near-Sun Comets

This review addresses our current understanding of comets that venture close to the Sun, and are hence exposed to much more extreme conditions than comets that are typically studied from Earth. The extreme solar heating and plasma environments that these objects encounter change many aspects of their behaviour, thus yielding valuable information on both the comets themselves that complements other data we have on primitive solar system bodies, as well as on the near-solar environment which they traverse. We propose clear definitions for these comets: We use the term near-Sun comets to encompass all objects that pass sunward of the perihelion distance of planet Mercury (0.307 AU). Sunskirters are defined as objects that pass within 33 solar radii of the Sun’s centre, equal to half of Mercury’s perihelion distance, and the commonly-used phrase sungrazers to be objects that reach perihelion within 3.45 solar radii, i.e. the fluid Roche limit. Finally, comets with orbits that intersect the solar photosphere are termed sundivers. We summarize past studies of these objects, as well as the instruments and facilities used to study them, including space-based platforms that have led to a recent revolution in the quantity and quality of relevant observations. Relevant comet populations are described, including the Kreutz, Marsden, Kracht, and Meyer groups, near-Sun asteroids, and a brief discussion of their origins. The importance of light curves and the clues they provide on cometary composition are emphasized, together with what information has been gleaned about nucleus parameters, including the sizes and masses of objects and their families, and their tensile strengths. The physical processes occurring at these objects are considered in some detail, including the disruption of nuclei, sublimation, and ionisation, and we consider the mass, momentum, and energy loss of comets in the corona and those that venture to lower altitudes. The different components of comae and tails are described, including dust, neutral and ionised gases, their chemical reactions, and their contributions to the near-Sun environment. Comet-solar wind interactions are discussed, including the use of comets as probes of solar wind and coronal conditions in their vicinities. We address the relevance of work on comets near the Sun to similar objects orbiting other stars, and conclude with a discussion of future directions for the field and the planned ground- and space-based facilities that will allow us to address those science topics

Comprehensive dosimetry for seven exposure sources at the earliest US uranium processing facility

Mallinckrodt Chemical Works (MCW) was the earliest uranium processing facility in the United States, beginning in 1942. The 2,514 workers included in the epidemiologic study were exposed to external gamma radiation, medical x-rays, internal radiation from intakes of pitchblende ore and its extracted radionuclides (mainly uranium isotopes and radium-226), and ambient levels of radon and its progeny [