Showing papers by "Norwegian Radiation Protection Authority published in 1996"

Relationship Between Intestinal Fibrosis and Histopathologic and Morphometric Changes in Consequential and Late Radiation Enteropathy

Abstract: Intestinal fibrosis is a marked feature of late radiation enteropathy. This study assessed the time dose fractionation relationships of radiation-induced fibrosis in order to elucidate possible pathogenetic mechanisms. In 290 male Sprague-Dawley rats, a loop of small bowel was transposed to the left side of the scrotum. Three weeks later, the transposed segment was irradiated with either single dose or various fractionated regimens. The animals were observed for radiation-induced intestinal complications and killed in groups, 2 and 26 weeks after completion of irradiation. A semiquantitative histopathologic radiation injury score, morphometry of the submucosa, submucosal arterioles, intestinal surface area, and relative collagen content were used as endpoints. Fibrosis, measured by collagen assay and radiation injury score, increased with total dose, increasing fraction size and reduction in overall treatment time. This paralleled the results of morphometric assessment of mucosal surface area. Differences in vascular morphometry were only statistically significant in response to changes in total dose and fraction size and not with changes in overall treatment time. We conclude that fibrosis increases with increasing observation time, increasing fraction size, increasing total dose, and reduction of interfraction interval. Consequential injury, occurring as a result of disruption of mucosal integrity, seems to be an important mechanism for development of intestinal fibrosis. In contrast, vascular injury is relatively independent of this mechanism.

Chromosome analysis of peripheral lymphocytes from persons exposed to radioactive fallout in Norway from the Chernobyl accident.

Abstract: Chromosome analysis of peripheral lymphocytes from two Norwegian populations (44 reindeer herding South samis from Roros and Snasa, 12 sheep farmers from Valdres) exposed to fallout from the Chernobyl accident were made. The doses from caesium through the years 1987–1991 were calculated based on whole-body measurement of 134 Cs and 137 Cs giving a total cumulative mean internal dose of 5.54 mSv for the total group of 56 persons. Chromosome aberrations were within the normal range when compared with historical controls with the exception of dicentrics (0.3% per cell, which is a 10-fold increase) and rings (0.07% per cell). A dose-dependent increase in dicentrics and rings based on caesium exposure was not observed.

Absence of relation between sick leave caused by musculoskeletal disorders and exposure to magnetic fields in an aluminum plant

Abstract: This is a study of the relationship between occupational exposure to magnetic fields in pot rooms and occurrence of sick leave caused by musculoskeletal disorders. The average exposure to static magnetic fields was 8 mT in the pot rooms. Ripple fields were recorded as well. A cohort of 342 exposed workers and 222 unexposed workers from the same electrolysis plant was retrospectively followed for 5 years. The reference group has a type of work similar to the exposed group except for the expose to magnetic fields. The occurrence of sick leave and the diagnoses causing the sick leave were obtained from the Occupational Health Care Unit: these data were stored in their computer files. The data were complete. No relationship between the occurrence of sick leave caused by musculoskeletal disorders and exposure to magnetic fields was found. This was the case for both the annual number of periods of sick leave and the total number of days with sick leave. The results must be interpreted with caution due to limitations in the design and available data. Also, static magnetic fields constituted the major exposure, and the results may be different when related to work in other types of magnetic-field exposure.

Norwegian Concerns Regarding Nuclear Submarine Decommission Activities

Abstract: Spent nuclear fuel and high level nuclear waste in interim storage on “floating bases” (ships) and on land at the Kola Peninsula, are a concern to authorities and population of Norway. The concern is more related to risk and consequences of major accidents than near term leakage of radioactive materials and present levels of radioactive contamination in air, on land, or in the sea. Interim storage for spent nuclear fuel for ship reactors in the area are reported to contain nearly 20,000 fuel assemblies. An equal amount of spent fuel is said to remain in nuclear submarines waiting to be decommissioned at naval bases and in shipyards.