| 1. |
- Eriksson, Mats, et al.
(författare)
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U, Pu, and Am nuclear signatures of the Thule hydrogen bomb debris
- 2008
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Ingår i: Environmental Science & Technology. - : American Chemical Society (ACS). - 1520-5851 .- 0013-936X. ; 42:13, s. 4717-4722
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Tidskriftsartikel (refereegranskat)abstract
- This study concerns an arctic marine environment that was contaminated by actinide elements after a nuclear accident in 1968, the so-called Thule accident. In this study we have analyzed five isolated hot particles as well as sediment samples containing particles from the weapon material for the determination of the nuclear fingerprint of the accident. We report that the fissile material in the hydrogen weapons involved in the Thule accident was a mixture of highly enriched uranium and weapon-grade plutonium and that the main fissile material was U-235 (about 4 times more than the mass of Pu-239). In the five hot particles examined, the measured uranium atomic ratio was U-235/U-238 = 1.02 +/- 0.16 and the Pu-isotopic ratios were as follows: Pu-240/Pu-239 0.0551 +/- 0.0008 (atom ratio), Pu-238/Pu239+240 = 0.0161 +/- 0.0005 (activity ratio), Pu-241/Pu239+240 = 0.87 +/- 0.12 (activity ratio), and Am-241/Pu239+240 = 0.169 +/- 0.005 (activity ratio) (reference date 2001-10-01). From the activity ratios of Pu-241/Am-241, we estimated the time of production of this weapon material to be from the late 1950s to the early 1960s. The results from reanalyzed bulk sediment samples showed the presence of more than one Pu source involved in the accident, confirming earlier studies. The Pu-238/Pu239+240 activity ratio and the Pu-240/Pu-239 atomic ratio were divided into at least two Pu-isotopic ratio groups. For both Pu-isotopic ratios, one ratio group had identical ratios as the five hot particles described above and for the other groups the Pu isotopic ratios were lower (Pu-238/Pu239+240 activity ratio similar to 0.01 and the Pu-240/Pu-239 atomic ratio 0.03). On the studied particles we observed that the U/Pu ratio decreased as a function of the time these particles were present in the sediment. We hypothesis that the decrease in the ratio is due to a preferential leaching of U relative to Pu from the particle matrix.
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| 2. |
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| 3. |
- Hansson, Edvin, 1987-, et al.
(författare)
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Particle Size-dependent Dissolution of Uranium Aerosols in Simulated Lung Fluid : A Case Study in a Nuclear Fuel Fabrication Plant
- 2022
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Ingår i: Health Physics. - : Lippincott, Williams & Wilkins. - 0017-9078 .- 1538-5159. ; 123:1, s. 11-27
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Tidskriftsartikel (refereegranskat)abstract
- Inhalation exposure to uranium aerosols can be a concern in nuclear fuel fabrication. The ICRP provides default absorption parameters for various uranium compounds but also recommends determination of material-specific absorption parameters to improve dose calculations for individuals exposed to airborne radioactivity. Aerosol particle size influences internal dosimetry calculations in two potentially significant ways: the efficiency of particle deposition in the various regions of the respiratory tract is dependent on aerodynamic particle size, and the dissolution rate of deposited materials can vary according to particle size, shape, and porosity because smaller particles tend to have higher surface-to-volume ratios than larger particles. However, the ICRP model assumes that deposited particles of a given material dissolve at the same rate regardless of size and that uptake to blood of dissolved material normally occurs instantaneously in all parts of the lung (except the anterior portion of the nasal region, where zero absorption is assumed). In the present work, the effect of particle size on dissolution in simulated lung fluid was studied for uranium aerosols collected at the plant, and its influence on internal dosimetry calculations was evaluated. Size fractionated uranium aerosols were sampled at a nuclear fuel fabrication plant using portable cascade impactors. Absorption parameters, describing dissolution of material according to the ICRP Human Respiratory Tract Model, were determined in vitro for different size fractions using simulated lung fluid. Samples were collected at 16 time-points over a 100-d period. Uranium content of samples was determined using inductively coupled plasma mass spectrometry and alpha spectrometry. In addition, supplementary experiments to study the effect of pH drift and uranium adsorption on filter holders were conducted as they could potentially influence the derived absorption parameters. The undissolved fraction over time was observed to vary with impaction stage cut-point at the four main workshops at the plant. A larger fraction of the particle activity tended to dissolve for small cut-points, but exceptions were noted. Absorption parameters (rapid fraction, rapid rate, and slow rate), derived from the undissolved fraction over time, were generally in fair agreement with the ICRP default recommendations for uranium compounds. Differences in absorption parameters were noted across the four main workshops at the plant (i.e., where the aerosol characteristics are expected to vary). The pelletizing workshop was associated with the most insoluble material and the conversion workshop with the most soluble material. The correlation between derived lung absorption parameters and aerodynamic particle size (impactor stage cut-point) was weak. For example, the mean absorption parameters derived from impaction stages with low (taken to be <5 mu m) and large (>= 5 mu m) cut-points did not differ significantly. Drift of pH and adsorption on filter holders appeared to be of secondary importance, but it was found that particle leakage can occur. Undissolved fractions and to some degree derived lung absorption parameters were observed to vary depending on the aerodynamic size fraction studied, suggesting that size fractionation (e.g., using cascade impactors) is appropriate prior to conducting in vitro dissolution rate experiments. The 0.01-0.02 mu m and 1-2 mu m size ranges are of particular interest as they correspond to alveolar deposition maxima in the Human Respiratory Tract Model (HRTM). In the present work, however, the dependency on aerodynamic size appeared to be of minor importance, but it cannot be ruled out that particle bounce obscured the results for late impaction stages. In addition, it was noted that the time over which simulated lung fluid samples are collected (100 d in our case) influences the curve-fitting procedure used to determine the lung absorption parameters, in particular the slow rate that increased if fewer samples were considered.
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| 4. |
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| 5. |
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| 6. |
- Lindahl, Patric, et al.
(författare)
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Performance and optimisation of triple quadrupole ICP-MS for accurate measurement of uranium isotopic ratios
- 2021
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Ingår i: Journal of Analytical Atomic Spectrometry. - : Royal Society of Chemistry. - 0267-9477 .- 1364-5544. ; 36:10, s. 2164-2172
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Tidskriftsartikel (refereegranskat)abstract
- The performance characteristics of the Agilent 8900 triple quadrupole inductively coupled plasma mass spectrometry (ICP-MS/MS) system were evaluated and optimised concerning stability in measurements of uranium isotopic ratios. Multiple measurement parameters were evaluated for the determination of U isotopic ratios in certified standard solutions containing U-233, U-235 and U-238. Large irregular biases during repeated measurements of U isotopic ratios were observed using two identical ICP-MS/MS instruments. Depending on the mass filter resolution settings, the accuracy of U isotopic ratios can deviate up to 100% from the certified reference value. These variations in U isotopic ratios are primarily recognised as irregular drifts in the mass calibration of the two mass filters. This mass calibration drift is dependent on the isotope mass with a more pronounced drift for heavier isotopes. In order to solve the problem the resolution settings were optimised for both mass filters, which resulted in considerable improvement in precision and accuracy. A precision of 0.07% (relative standard deviation) for long-term measurement of U-233/U-235 ratios was achieved. Mass bias corrected U isotopic ratios agree very well with certified reference values with overall relative deviations from reference values of 0.005% and 0.17% for the SQ mode and MS/MS mode, respectively. The impact of the first mass filter in the MS/MS mode has a significant effect on the mass bias discrimination process and hence the accuracy of U isotopic ratios.
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| 7. |
- Lindahl, Patric
(författare)
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Studies of Long-lived Radionuclides in the Environment - with Emphasis on 99Tc, 237Np and Pu Isotopes
- 2003
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Studies of the long-lived anthropogenic radionuclides 99Tc, 237Np, 239Pu and 240Pu were performed in marine and terrestrial areas contaminated by different accidental and controlled releases of radioactive materials. The three main sources discussed in this thesis are nuclear weapons tests, nuclear reprocessing plants and the Chernobyl accident. Results are mainly based on measurements of environmental samples collected in different parts of Sweden. An analytical method for trace analysis of plutonium and neptunium in environmental samples using ICP-MS (Inductively Coupled Plasma Mass Spectrometry) is described, and the results compared with those from conventional alpha spectrometry. The use of activated carbon filters for the separation of 99Tc from marine waters, with an adsorption efficiency in the range of 70%, is described. During 1991, 1995 and 2001 brown seaweed samples were collected at several stations along the Swedish west coast. In addition to these locations, a well-defined site (Särdal; 56.76 °N, 12.63 °E) was included from which 99Tc data were collected from 1967 to 2000. The effect of discharges from the Sellafield EARP (Enhanced Actinide Removal Plant) from 1995-1996 was observed in brown seaweed from the Swedish west coast 4-5 years later, with a ten-fold increase in 99Tc activity concentration. An inverse correlation between 99Tc and 137Cs concentrations in seaweed was observed due to continuous mixing of high-Tc-low-Cs (Atlantic Sea) and low-Tc-high-Cs (Baltic Sea) waters. Radioactive materials from the Chernobyl accident contaminated various part of Sweden and by analysing lichen samples from different areas an estimate of the deposited 237Np density could be made. Through the determination of 240Pu/239Pu and 237Np/239Pu atomic ratios, source identification could be made in Swedish lichen samples. In the areas most contaminated by the Chernobyl accident in Sweden, the Chernobyl-derived 237Np contribution was up to 30% of the total concentration. However, the plutonium contributions from Chernobyl in the same samples were as high as 85%. Sellafield-derived 237Np was found in brown seaweed samples from the Swedish west coast, indicating greater mobility in the marine environment than that of Pu.
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| 8. |
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| 9. |
- Lindahl, Patric, et al.
(författare)
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Total dissolution of environmental samples for the determination of uranium and thorium by ICP-MS and alpha-particle spectrometry
- 2022
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Ingår i: Applied Radiation and Isotopes. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0969-8043 .- 1872-9800. ; 181
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Tidskriftsartikel (refereegranskat)abstract
- A low-cost total dissolution method for accurate determination of uranium and thorium isotopes in environmental samples (soil and sediment) was introduced, optimised and validated. The method included alkaline fusion based on sodium hydroxide (NaOH) and sodium peroxide (Na2O2), followed by sequential extraction chromatography separation and measurements with ICP-MS or alpha-particle spectrometry. The overall chemical recoveries for U and Th for the entire procedure were about 80% and 90%, respectively. The U-238 contribution from partial dissolution of the nickel crucibles accounted for about 80% of the total background activity.
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| 10. |
- Olszewski, Grzegorz, et al.
(författare)
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Development of Gd-148 analysis method using stable Gd
- 2021
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Ingår i: Talanta. - : Elsevier. - 0039-9140 .- 1873-3573. ; 229
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Tidskriftsartikel (refereegranskat)abstract
- The analytical method of Gd determination was developed with the aim to analyse Gd-148 in environmental and bioassay samples. It involves the use of anion exchange resin, extraction chromatography, and cation exchange resin. Alkaline fusion and calcium oxalate co-precipitation are used for solid samples dissolution and liquid samples preconcentration, respectively. Total method recovery was tested with natural Gd (Gd-157) using ICP-QQQ-MS. A maximum total recovery of 75 % was obtained.
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| 11. |
- Olszewski, Grzegorz, et al.
(författare)
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On the distribution and inventories of radionuclides in dated sediments around the Swedish coast
- 2018
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Ingår i: Journal of Environmental Radioactivity. - : ELSEVIER SCI LTD. - 0265-931X .- 1879-1700. ; 186, s. 142-151
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Tidskriftsartikel (refereegranskat)abstract
- The activity concentrations and distribution of Cs-137, 238pu (239)I(-240)pu, Am-241,and Pb-210 was determined by the analysis of six sediment cores from the Baltic Sea and Kattegat. The chronology of the sediment cores has been used to evaluate the origin and time trend of the radionuclide sources in these sediments. The sediment cores were dated with a Pb-210 model and the results were validated with fallout peaks, assumed to originate from the global nuclear weapons testing and the Chernobyl accident. Source identification, using the isotopic and radionuclide activity ratios, showed that the Chernobyl accident is the main source of Cs-137 in the Baltic Sea; for Pu239+24 and Am-241 the dominant source was shown to be fallout from nuclear weapons tests. For (PU)-P-238 and 2(41)Am the Chernobyl accident had a significant impact on the direct fallout into the Baltic Proper, with up to a 65% contribution in the sediment slices dated to 1986. In these sediment slices the maximum activity ratios of (238)pu/(239+240)pu and (241)Am(/2394-240)pu were 0.314 +/- 0.008 and 1.29 +/- 0.06, respectively. The ratios clearly deviate from the corresponding ratios for global nuclear weapons fallout (around 0.028 and 0.54, respectively). Calculated inventories were 63 (175)Bq-m(-2) for 239+240PII, 2.8-7.8 for Pu-238 Bq-m(-2) and 0.92-44.4 kBq-m(-2) for Cs-137. Different fallout patterns for Cs-137 and plutonium isotopes from the Chernobyl accident were confirmed through depth profiles analyses. The maximum inventory of 137Cs was observed in the Bothnian Sea, while Chernobyl derived plutonium was found to be mostly present in Northern Baltic Proper. The radionuclides distribution in the depth profiles shows how contaminated water affects the sediment as it passes sampling stations according to the current circulation pattern in the Baltic Sea. Additionally, the effect of increased activity concentrations from of river discharges in the most contaminated area in the Bothnian Sea was observed. (C) 2017 Elsevier Ltd. All rights reserved.
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| 12. |
- Synnergren, Jane, 1967, et al.
(författare)
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Cardiomyogenic gene expression profiling of differentiating human embryonic stem cells.
- 2008
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Ingår i: Journal of biotechnology. - : Elsevier BV. - 0168-1656 .- 1873-4863. ; 134:1-2, s. 162-70
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Tidskriftsartikel (refereegranskat)abstract
- Human embryonic stem cells (hESCs) can differentiate into a variety of specialized cell types. Thus, they provide a model system for embryonic development to investigate the molecular processes of cell differentiation and lineage commitment. The development of the cardiac lineage is easily detected in mixed cultures by the appearance of spontaneously contracting areas of cells. We performed gene expression profiling of undifferentiated and differentiating hESCs and monitored 468 genes expressed during cardiac development and/or in cardiac tissue. Their transcription during early differentiation of hESCs through embryoid bodies (EBs) was investigated and compared with spontaneously differentiating hESCs maintained on feeders in culture without passaging (high-density (HD) protocol). We observed a larger variation in the gene expression between cells from a single cell line that were differentiated using two different protocols than in cells from different cell lines that were cultured according to the same protocol. Notably, the EB protocol resulted in more reproducible transcription profiles than the HD protocol. The results presented here provide new information about gene regulation during early differentiation of hESCs with emphasis on the cardiomyogenic program. In addition, we also identified regulatory elements that could prove critical for the development of the cardiomyocyte lineage.
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| 13. |
- Synnergren, Jane, 1967, et al.
(författare)
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Differentiating human embryonic stem cells express a unique housekeeping gene signature.
- 2007
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Ingår i: Stem cells (Dayton, Ohio). - : Oxford University Press (OUP). - 1066-5099 .- 1549-4918. ; 25:2, s. 473-80
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Tidskriftsartikel (refereegranskat)abstract
- Housekeeping genes (HKGs) are involved in basic functions needed for the sustenance of the cell and are assumed to be constitutively expressed at a constant level. Based on these features, HKGs are frequently used for normalization of gene expression data. In the present study, we used the CodeLink Gene Expression Bioarray system to interrogate changes in gene expression occurring during differentiation of human ESCs (hESCs). Notably, in the three hESC lines used for the study, we observed that the RNA levels of 56 frequently used HKGs varied to a degree that rendered them inappropriate as reference genes. Therefore, we defined a novel set of HKGs specifically for hESCs. Here we present a comprehensive list of 292 genes that are stably expressed (coefficient of variation <20%) in differentiating hESCs. These genes were further grouped into high-, medium-, and low-expressed genes. The expression patterns of these novel HKGs show very little overlap with results obtained from somatic cells and tissues. We further explored the stability of this novel set of HKGs in independent, publicly available gene expression data from hESCs and observed substantial similarities with our results. Gene expression was confirmed by real-time quantitative polymerase chain reaction analysis. Taken together, these results suggest that differentiating hESCs have a unique HKG signature and underscore the necessity to validate the expression profiles of putative HKGs. In addition, this novel set of HKGs can preferentially be used as controls in gene expression analyses of differentiating hESCs.
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| 14. |
- Synnergren, Jane, et al.
(författare)
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Differentiating human embryonic stem cells express a unique housekeeping gene signature
- 2006
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Ingår i: 4th ISSCR Annual Meeting.
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Konferensbidrag (refereegranskat)abstract
- Human embryonic stem cells (hESCs) represent populations of pluripotent undifferentiated cells with unlimited replication capacity which can be coaxed to differentiate into a variety of specialized cells. As a result, there is great hope that hESCs will be extremely useful by providing platforms for various in vitro applications (e.g. in drug discovery) as well as for future use of hESCs and their differentiated progeny in cell replacement therapies. In order to realize the potential of hESCs, it is necessary to gain much deeper knowledge about the processes that govern differentiation of these cells.In recent years, significant progress towards understanding cellular differentiation has been fuelled, in part, by studying gene expression using microarrays. In this large scale studies, statistical methods are used to normalize the gene expression data and render comparisons between different samples. In lower throughput analyses, RNA levels in hESCs are also measured using RT-PCR requiring normalization of the gene expression data to adequately correct for inter-sample variation. In general, investigators have used the traditional housekeeping genes (HKGs) (e.g. GAPDH, b-tubulin, b-actin) in studies of hESCs. HKGs are involved in basic functions needed for the sustenance of the cell and are assumed to be constitutively expressed at a constant level. Based on these features, HKGs are frequently used for normalization of gene expression data. However, it is well known that the expression of several of these genes vary considerably in adult tissues and their suitability as HKGs in hESCs remains to be proven. In this regard, the RNA levels of HPRT and b-tubulin were shown to vary substantially in differentiating mouse ESCs.In the present study, we used the CodeLinkTM Gene Expression Bioarray system to interrogate changes in gene expression occurring during differentiation of hESCs. Notably, in the three hESC lines used for the study, we observed that the RNA levels of 56 frequently used HKGs varied to a degree that rendered them inappropriate as reference genes. Therefore, we defined a novel set of HKGs specifically for hESCs. Here we present a comprehensive list of 292 genes that are stably expressed (coefficient of variation<20%) in differentiating hESCs. These genes were further grouped into high, medium, and low expressed genes. The expression patterns of these novel HKGs show very little overlap with results obtained from somatic cells and tissues. We further explored the stability of this novel set of HKGs in independent, publicly available gene expression data from hESCs and observed substantial similarities in terms of stably expressed genes. Taken together, these results suggest that hESCs have a unique HKG signature and underscore the necessity to validate the expression profiles of putative HKGs. In addition, the novel set of identified HKGs can preferentially be used as controls in gene expression analyses of differentiating hESCs.
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| 15. |
- Yndigegn, T., et al.
(författare)
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Beta-Blockers after Myocardial Infarction and Preserved Ejection Fraction
- 2024
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Ingår i: New England Journal of Medicine. - : MASSACHUSETTS MEDICAL SOC. - 0028-4793 .- 1533-4406.
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Tidskriftsartikel (refereegranskat)abstract
- Background Most trials that have shown a benefit of beta-blocker treatment after myocardial infarction included patients with large myocardial infarctions and were conducted in an era before modern biomarker-based diagnosis of myocardial infarction and treatment with percutaneous coronary intervention, antithrombotic agents, high-intensity statins, and renin-angiotensin-aldosterone system antagonists.Methods In a parallel-group, open-label trial performed at 45 centers in Sweden, Estonia, and New Zealand, we randomly assigned patients with an acute myocardial infarction who had undergone coronary angiography and had a left ventricular ejection fraction of at least 50% to receive either long-term treatment with a beta-blocker (metoprolol or bisoprolol) or no beta-blocker treatment. The primary end point was a composite of death from any cause or new myocardial infarction.Results From September 2017 through May 2023, a total of 5020 patients were enrolled (95.4% of whom were from Sweden). The median follow-up was 3.5 years (interquartile range, 2.2 to 4.7). A primary end-point event occurred in 199 of 2508 patients (7.9%) in the beta-blocker group and in 208 of 2512 patients (8.3%) in the no-beta-blocker group (hazard ratio, 0.96; 95% confidence interval, 0.79 to 1.16; P=0.64). Beta-blocker treatment did not appear to lead to a lower cumulative incidence of the secondary end points (death from any cause, 3.9% in the beta-blocker group and 4.1% in the no-beta-blocker group; death from cardiovascular causes, 1.5% and 1.3%, respectively; myocardial infarction, 4.5% and 4.7%; hospitalization for atrial fibrillation, 1.1% and 1.4%; and hospitalization for heart failure, 0.8% and 0.9%). With regard to safety end points, hospitalization for bradycardia, second- or third-degree atrioventricular block, hypotension, syncope, or implantation of a pacemaker occurred in 3.4% of the patients in the beta-blocker group and in 3.2% of those in the no-beta-blocker group; hospitalization for asthma or chronic obstructive pulmonary disease in 0.6% and 0.6%, respectively; and hospitalization for stroke in 1.4% and 1.8%.Conclusions Among patients with acute myocardial infarction who underwent early coronary angiography and had a preserved left ventricular ejection fraction (>= 50%), long-term beta-blocker treatment did not lead to a lower risk of the composite primary end point of death from any cause or new myocardial infarction than no beta-blocker use. (Funded by the Swedish Research Council and others; REDUCE-AMI ClinicalTrials.gov number, NCT03278509.) Hospitalized patients with acute myocardial infarction and preserved EF were assigned to receive open-label long-term beta-blocker therapy or not. Beta-blockers did not lead to a lower risk of death or MI.
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| 16. |
- Yndigegn, Troels, et al.
(författare)
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Design and rationale of randomized evaluation of decreased usage of beta-blockers after acute myocardial infarction (REDUCE-AMI)
- 2022
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Ingår i: European Heart Journal - Cardiovascular Pharmacotherapy. - : Oxford University Press. - 2055-6837 .- 2055-6845. ; 9:2, s. 192-197
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Most trials showing benefit of beta-blocker treatment after myocardial infarction (MI) included patients with large MIs and are from an era before modern biomarker-based MI diagnosis and reperfusion treatment. The aim of the Randomized Evaluation of Decreased Usage of betabloCkErs after Acute Myocardial Infarction (REDUCE-AMI) trial is to determine whether long-term oral beta-blockade in patients with an acute MI and preserved left ventricular ejection fraction (EF) reduces the composite endpoint of death of any cause or recurrent MI.METHODS: It is a registry-based, randomized, parallel, open-label, multicenter trial performed at 38 centers in Sweden, one center in Estonia and six centers in New Zealand. About 5000 patients with an acute MI who have undergone coronary angiography and with EF ≥ 50% will be randomized to long-term treatment with beta-blockade or not. The primary endpoint is the composite endpoint of death of any cause or new non-fatal MI. There are several secondary endpoints, including all-cause death, cardiovascular death, new MI, readmission because of heart failure and atrial fibrillation, symptoms, functional status, health related quality of life after 6-10 weeks and after 1 year of treatment. Safety endpoints are bradycardia, AV-block II-III, hypotension, syncope or need for pacemaker, asthma or chronic obstructive pulmonary disease and stroke.CONCLUSION: The results from REDUCE-AMI will add important evidence regarding the effect of beta-blockers in patients with MI and preserved EF and may change guidelines and clinical practice.
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| 17. |
- Yusuf, Ibtisam, et al.
(författare)
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Particle Size Dependent Dissolution of Uranium Aerosols in Simulated Gastrointestinal Fluids
- 2023
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Ingår i: Health Physics. - : LIPPINCOTT WILLIAMS & WILKINS. - 0017-9078 .- 1538-5159. ; 124:4, s. 285-300
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Tidskriftsartikel (refereegranskat)abstract
- Uranium aerosol exposure can be a health risk factor for workers in the nuclear fuel industry. Good knowledge about aerosol dissolution and absorption characteristics in the gastrointestinal tract is imperative for solid dose assessments and risk management. In this study, an in vitro dissolution model of the GI tract was used to experimentally study solubility of size-fractionated aerosols. The aerosols were collected from four major workshops in a nuclear fuel fabrication plant where uranium compounds such as uranium hexafluoride (UF6), uranium dioxide (UO2), ammonium uranyl carbonate, AUC [UO2CO3 center dot 2(NH4)(2)CO3] and triuranium octoxide (U3O8) are present. The alimentary tract transfer factor, f(A), was estimated for the aerosols sampled in the study. The transfer factor was derived from the dissolution in the small intestine in combination with data on absorption of soluble uranium. Results from the conversion workshop indicated a f(A) in line with what is recommended (0.004) by the ICRP for inhalation exposure to Type M materials. Obtained transfer factors, f(A), for the powder preparation and pelletizing workshops where UO2 and U3O8 are handled are lower for inhalation and much lower for ingestion than those recommended by the ICRP for Type M/S materials f(A) = 0.00029 and 0.00016 vs. 0.0006 and 0.002, respectively. The results for ingestion and inhalation f(A) indicate that ICRPs conservative recommendation of f(A) for inhalation exposure is applicable to both ingestion and inhalation of insoluble material in this study. The dissolution- and subsequent absorption-dependence on particle size showed correlation only for one of the workshops (pelletizing). The absence of correlation at the other workshops may be an effect of multiple chemical compounds with different size distribution and/or the reported presence of agglomerated particles at higher cut points having more impact on the dissolution than particle size. The impact on dose coefficients [committed effective dose (CED) per Bq] of using experimental f(A) vs. using default f(A) recommended by the ICRP for the uranium compounds of interest for inhalation exposure was not significant for any of the workshops. However, a significant impact on CED for ingestion exposure was observed for all workshops when comparing with CED estimated for insoluble material using ICRP default f(A). This indicates that the use of experimentally derived site-specific f(A) can improve dose assessments. It is essential to acquire site-specific estimates of the dissolution and absorption of uranium aerosols as this provides more realistic and accurate dose- and risk-estimates of worker exposure. In this study, the results indicate that ICRPs recommendations for ingestion of insoluble material might overestimate absorption and that the lower f(A) found for inhalation could be more realistic for both inhalation and ingestion of insoluble material.
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