Analyses of combined mortality data on workers at the Hanford Site, Oak Ridge National Laboratory, and Rocky Flats Nuclear Weapons Plant

An important objective of studies of workers exposed occupationally to chronic low doses of ionizing radiation is to provide a direct assessment of health risks resulting from this exposure. This objective is most effectively accomplished by conducting combined analyses that allow evaluation of the totality of evidence from all study populations. In this paper, combined analyses of mortality in workers at the Hanford Site, Oak Ridge National Laboratory, and Rocky Flats Nuclear Weapons Plant are presented. These combined analyses provide no evidence of a correlation between radiation exposure and mortality from all cancer or from leukemia. Of 11 other specific types of cancer analyzed, multiple myeloma was the only cancer found to exhibit a statistically significant correlation with radiation exposure. Estimates of the excess risk of all cancer and of leukemia, based on the combined data, were negative. Upper confidence limits based on the combined data were lower than for any single population, and were similar to estimates obtained from recent analyses of A-bomb survivor data. These results strengthen support for the conclusion that estimates obtained through extrapolation from high-dose data do not seriously underestimate risks of low-dose exposure, but leave open the possibility that extrapolation may overestimate risks.     

Radiological Benchmarks for Effects on Aquatic Biota at the Oak Ridge Reservation

Radiological benchmarks for aquatic biota were developed for use at the U.S. Department of Energy's Oak Ridge Reservation as screening values to determine the spatial extent of potential ecological effects and to identify the need for additional site-specific investigation. The Point Source Dose Distribution approach was used to calculate water and sediment activities for selected radionuclides that result in a total dose rate to small and large fish of 1 Rad d^?1, which is the National Council on Radiation Protection and Measurements recommended acceptable dose rate to natural populations of aquatic biota. These screening values incorporate internal and external exposures from parent isotopes and all short-lived daughter products. They also include exposures from all major alpha, beta, and gamma emissions for each isotope. Unlike exposures to chemicals, exposures to radionuclides are expressed as the dose rate received by the organism. Dose rates that account for the biological effects to the organism are additive. If the total dose rate from all radionuclides and pathways exceeds a recommended acceptable dose rate, further analysis is needed to determine the hazards posed by radionuclides. If, however, the total dose rate falls below an acceptable dose rate, radionuclides may be eliminated from further study.     

An Oak Ridge legacy: the specific locus test and its role in mouse mutagenesis.

Mutations in the genes encoding single-strand DNA-specific exonucleases (ssExos) of Escherichia coli were examined for effects on mutation avoidance, UV repair, and conjugational recombination. Our results indicate complex and partially redundant roles for ssExos in these processes. Although biochemical experiments have implicated RecJ exonuclease, Exonuclease I (ExoI), and Exonuclease VII (ExoVII) in the methyl-directed mismatch repair pathway, the RecJ- ExoI- ExoVII- mutant did not exhibit a mutator phenotype in several assays for base substitution mutations. If these exonucleases do participate in mismatch excision, other exonucleases in E. coli can compensate for their loss. Frameshift mutations, however, were stimulated in the RecJ- ExoI- ExoVII- mutant. For acridine-induced frameshifts, this mutator effect was due to a synergistic effect of ExoI- and ExoVII- mutations, implicating both ExoI and ExoVII in avoidance of frameshift mutations. Although no single exonuclease mutant was especially sensitive to UV irradiation, the RecJ- ExoVII- double mutant was extremely sensitive. The addition of an ExoI- mutation augmented this sensitivity, suggesting that all three exonucleases play partially redundant roles in DNA repair. The ability to inherit genetic markers by conjugation was reduced modestly in the ExoI- RecJ- mutant, implying that the function of either ExoI or RecJ exonucleases enhances RecBCD-dependent homologous recombination.     

Governing the Interplay between Industrial Ecosystems and Environmental Regulation

Many scholars of industrial ecology have focused on the institutional and organizational challenges of building and maintaining regional industrial symbiosis through the synergistic integration of material and energy flows. Despite the promise that these intellectual developments hold for the future dematerialization of industrial production, they rarely address the actual regulatory obstacles of turning wastes into raw materials. In this article we introduce a potential future industrial symbiosis around the Gulf of Bothnia between Finland and Sweden, and assess the regulatory bottlenecks related to waste by‐product consideration. We find that although the Gulf of Bothnia region has technological and economic potential for industrial symbiosis, the regulatory support for this is insufficient. We suggest a common pool resource‐based governance system that could utilize market and regulatory mechanisms in a regional‐level cross‐border system of governance. Importantly, the suggested governance system would protect the users of potential raw materials from unpredictable waste regulation, market risks related to large‐scale material flows, and societal risks of hazardous waste treatment.     

Mercury uptake and translocation in Impatiens walleriana plants grown in the contaminated soil from Oak Ridge

Mercury (Hg) contaminated soils from Oak Ridge, Tennessee were investigated for phytoavailability of mercury as measured by degree of Hg translocation in aboveground biomass of Impatiens walleriana plants grown in the soils. After 90 days of incubation, results revealed a higher concentration of total Hg in the leaves than in the flowers or the stems. Plants that were grown in the soils with higher Hg concentrations showed significantly higher Hg uptake and translocation in the aboveground plant-biomass, and the correlation with the initial soil-Hg was significant for the leaves and the stems in the plants that were tested. On an average, only 4.06 microg of Hg could be found in the above ground plant biomass of all the plants, compared to an average 3673.50 microg of initial total Hg concentrations in these soils. Statistical analysis revealed a greater affinity of Hg for the soil carbon, which supported the finding of this study on low soil Hg bioavailability.     

Antarctic Stream Ecosystems: Variability in Environmental Properties and Algal Community Structure

The variability in physical, chemical and biological properties was examined for a number of glacier melt streams in south Victoria Land, Antarctica. Streams flowed for between one and two months. Stream water temperatures (range = 0–11°C) varied over short (hr) time scales whilst discharges varied considerably between streams (range 0.001–15 m³s⁻¹) and over diel cycles. Solar radiation and air temperature were major determinants of stream discharge. Variability in discharge was reflected in variability in nutrient chemistry and sediment load. Nitrogen and phosphorus varied considerably between streams; the meltwaters early in summer contained 10–20 times higher levels of dissolved N and P than later in the season. Within stream nutrient levels were modified by dense algal growths and penguin rookeries. Epilithic algal communities were made up predominantly of cyanophyceae which formed mats and crusts. Longitudinal and horizontal variability of species in the communities in selected streams is described. Analyses of algal cover and biomass (chlorophyll a) show that substrate type and flow rates are of greater importance than nutrients in influencing algal abundance and biomass. In some streams biomass values of over 20 μg Ch. a cm⁻² were recorded, much of which remains viable but inactive over the antarctic winter.