The Derivation of Transfer Parameters in the Assessment of Radiological Impacts on Arctic Marine Biota

The initial stage of an environmental impact assessment requires quantification of radionuclide transfer in the study area. This paper evaluates the robustness of the concentration factor (CF) approach in assessing radiological impact on reference Arctic marine biota. By comparing region-specific data sets with recommended generic values for CFs, we tested the hypothesis that transfers to Arctic biota differ from transfers observed in temperate areas for 90Sr, 137Cs, 239, 240Pu and 99Tc. Despite the general paucity of data and great uncertainty regarding radionuclide CFs in reference biota, we conclude that the use of Arctic-specific CFs for Sr and Pu can be justified in some cases where differences from generic CFs seem apparent. Where CF data are absent, a biokinetic modelling approach with allometric considerations might be used to bridge data gaps. Such an approach has been used here to estimate the trophic transfer of 137Cs and 239Pu in a marine food chain consisting of four trophic levels. For the simulation concerning 137Cs, the preliminary results suggest that it takes more than five years to attain equilibrium for higher trophic levels (polar cod and harp seal). Biomagnification appears to occur at the lower trophic levels, but not at the highest (seal). For 239Pu, transfer to successively higher trophic levels is low: there is a fall of several orders of magnitude between primary producers, represented by phytoplankton, and polar cod, representing trophic levels 3 and 4. However, the model predicts that this decreasing trend in activity concentrations along the food chain is reversed for the highest trophic level, represented by seal. The simulated results for seal display equilibrium activity concentrations about two orders of magnitude higher than those observed for polar cod (one of its prey species). However, equilibrium (165 years) is not reached during the life span of a seal. The equilibrium 137Cs CFs are approximately 50 l/kg for zooplankton, 130l/kg for polar cod, and 70 l/kg for seal. The predicted equilibrium 239Pu CFs are 2.5·10³ l/kg for zooplankton and 25 l/kg for polar cod. For seal, following a one-year equilibration period, a CF of approximately 75 l/kg is predicted.Le stade initial d'une étude d'impact environnemental nécessite une évaluation quantitative du transfert de radionucléides dans la zone d'étude. Cet article évalue la robustesse de la méthode du facteur de concentration (FC) pour déterminer l'impact radiologique sur un biote marin arctique de référence. En comparant des ensembles de données spécifiques à une région avec des valeurs génériques recommandées pour les facteurs de concentration, on a testé l'hypothèse selon laquelle les transferts au biote arctique diffèrent des transferts observés dans des régions tempérées pour 90Sr, 137Cs, 239,240Pu et 99Tc. Malgré la pénurie générale de données et un haut niveau d'incertitude concernant les FC des radionucléides dans le biote de référence, on conclut que l'utilisation de FC spécifiques à l'Arctique pour Sr et Pu peut être justifiée dans certains cas où les différences d'avec les FC génériques semblent apparentes. Là où il n'existe pas de données sur les FC, on peut recourir à la modélisation biocinétique tenant compte des éléments allométriques afin de combler les lacunes dans les données. C'est cette approche que l'on a utilisée ici pour estimer le transfert trophique de 137Cs et de 239Pu dans une chaîne alimentaire marine comprenant quatre niveaux trophiques. Pour la simulation relative à 137Cs, les résultats préliminaires suggèrent qu'il faut plus de cinq ans pour atteindre l'équilibre aux niveaux trophiques supérieurs (morue polaire et phoque annelé). La bioamplification semble se produire aux niveaux trophiques inférieurs, mais pas au plus élevé (phoque). Pour 239Pu, le transfert aux niveaux trophiques supérieurs est faible: on constate une baisse de plusieurs ordres de grandeur entre les producteurs primaires, représentés par le phytoplancton, et la morue polaire, qui représente les niveaux trophiques 3 et 4. Le modèle prédit toutefois que cette tendance à la baisse dans l'activité volumique le long de la chaîne alimentaire s'inverse au niveau trophique le plus élevé, représenté par le phoque. Les résultats simulés pour le phoque affichent des activités volumiques à l'équilibre environ deux ordres de grandeur plus élevées que celles observées chez la morue polaire (l'une des espèces-proies du phoque). L'équilibre (165 ans) n'est cependant pas atteint durant la durée de vie du phoque. Les FC de 137Cs à l'équilibre sont environ de 50 l/kg pour le zooplancton, de 130 l/kg pour la morue polaire et de 70 l/kg pour le phoque. Les FC de 239Pu projetés à l'équilibre sont de 2,5·10³ l/kg pour le zooplancton et de 25 l/kg pour la morue polaire. Pour le phoque, après une période d'équilibre d'une année, on prédit un FC d'environ 75 l/kg

Geographical variation in radiological services: a nationwide survey

BACKGROUND: Geographical variation in health care services challenges the basic principle of fair allocation of health care resources. This study aimed to investigate geographical variation in the use of X-ray, CT, MRI and Ultrasound examinations in Norway, the contribution from public and private institutions, and the impact of accessibility and socioeconomic factors on variation in examination rates. METHODS: A nationwide survey of activity in all radiological institutions for the year 2002 was used to compare the rates per thousand of examinations in the counties. The data format was files/printouts where the examinations were recorded according to a code system. RESULTS: Overall rates per thousand of radiological examinations varied by a factor of 2.4. The use of MRI varied from 170 to 2, and CT from 216 to 56 examinations per 1000 inhabitants. Single MRI examinations (knee, cervical spine and head/brain) ranged high in variation, as did certain other spine examinations. For examination of specific organs, the counties' use of one modality was positively correlated with the use of other modalities. Private institutions accounted for 28% of all examinations, and tended towards performing a higher proportion of single examinations with high variability. Indicators of accessibility correlated positively to variation in examination rates, partly due to the figures from the county of Oslo. Correlations between examination rates and socioeconomic factors were also highly influenced by the figures from this county. CONCLUSION: The counties use of radiological services varied substantially, especially CT and MRI examinations. A likely cause of the variation is differences in accessibility. The coexistence of public and private institutions may be a source of variability, along with socioeconomic factors. The findings represent a challenge to the objective of equality in access to health care services, and indicate a potential for better allocation of overall health care resources. PREVIOUS PUBLICATION: The data applied in this article was originally published in Norwegian in: Børretzen I, Lysdahl KB, Olerud HM: Radiologi i Noreg – undersøkingsfrekvens per 2002, tidstrendar, geografisk variasjon og befolkningsdose. StrålevernRapport 2006:6. Østerås: The Norwegian Radiation Protection Authority. The Norwegian Radiation Protection Authority has given the authors permission to republish the data

Magnetic resonance imaging of the knee in Norway 2002–2004 (national survey): rapid increase, older patients, large geographic differences

<p>Abstract</p> <p>Background</p> <p>Magnetic resonance imaging (MRI) of the knee is the second most common MRI examination in Norway after head/brain MRI. Little has been published internationally on trends in the use of knee MRI after 1999. This study aimed to describe levels and trends in ambulant knee MRI utilisation in Norway 2002–2004 in relation to type of radiology service, geographic regions, number of MRI-scanners, patient age and gender, and type of referring health care provider.</p> <p>Methods</p> <p>We analysed administrative data on all claims for reimbursement of ambulant knee MRI performed in Norway in 2002, 2003 and 2004 and noted nominal reimbursement. We also recorded the referring health care provider from clinical requests of ambulant knee MRI done consecutively during two months in 2004 at one private institute and three hospitals. Number of MRI-scanners was given by manufacturers and radiology services.</p> <p>Results</p> <p>In Norway, the rate of knee MRI claims for 2004 was 15.6 per 1000 persons. This rate was 74% higher in East than in North region (18.4 vs. 10.6), slightly higher for men than women (16.4 vs. 14.7) and highest for ages 50–59 years (29.0) and 60–69 years (21.2). Most claims (76% for 2004) came from private radiology services. In 2004, the referring health care provider was a general practitioner in 63% of claims (unspecified in 24%) and in 83.5% (394/472) of clinical requests. From 2002 to 2004, the rate of knee MRI claims increased 64%. In the age group 50 years or above the increase was 86%. Rate of MRI-scanners increased 43% to 21 scanners per million persons in 2004. Reimbursement for knee MRI claims (nominal value) increased 80% to 70 million Norwegian kroner in 2004.</p> <p>Conclusion</p> <p>Ambulant knee MRI utilisation in Norway increases rapidly especially for patients over 50, and shows large geographic differences. Evaluation of clinical outcomes of this activity is needed together with clinical guidelines for use of knee MRI.</p

The ERICA Tool

The ERICA Tool is a computerised, flexible software system that has a structure based upon the ERICA Integrated Approach to assessing the radiological risk to biota. The Tool guides the user through the assessment process, recording information and decisions and allowing the necessary calculations to be performed to estimate risks to selected animals and plants. Tier 1 assessments are media concentration based and use pre-calculated environmental media concentration limits to estimate risk quotients. Tier 2 calculates dose rates but allows the user to examine and edit most of the parameters used in the calculation including concentration ratios, distribution coefficients, percentage dry weight soil or sediment, dose conversion coefficients, radiation weighting factors and occupancy factors. Tier 3 offers the same flexibility as Tier 2 but allows the option to run the assessment probabilistically if the underling parameter probability distribution functions are defined. Results from the Tool can be put into context using incorporated data on dose–effects relationships and background dose rates

Rheumatoid factors in primary Sjögren's syndrome (pSS) use diverse VH region genes, the majority of which show no evidence of somatic hypermutation

Rheumatoid factor (RF) is the most common autoantibody found in patients with Sjögren's syndrome (SS). To study the genetic origin and the mechanisms acting behind its generation we have characterized and sequenced the immunoglobulin VH genes used by 10 IgM RF MoAbs derived from peripheral blood of six female patients with pSS. We compared the structure of the RF immunoglobulin VH genes with those obtained previously from rheumatoid arthritis (RA) patients and healthy immunized donors (HID). VH1 and VH4 were each used by four RF clones, one clone was encoded by VH3 family gene and one by VH2 family gene. This distribution frequency was different from that observed in RA, where VH3 was the dominant family, followed by VH1. Eight different germ-line (GL) genes encoded the clones and all of these genes were seen previously in RA and/or HID RF. Five clones rearranged to JH6, four rearranged to JH4 and one to JH5, in contrast to RF from RA and HID, where JH4 was most frequently used. D segment use and CDR3 structure were diverse. Interestingly, three out of four VH4 clones used the GL gene DP-79 that was seen frequently in RA RF. The degree of somatic mutation in the pSS RF was very much lower than seen in RA and HID RF. All the pSS RF clones except three were in or very close to GL configuration. This indicates that there is little role for somatic hypermutation and a germinal centre reaction in the generation of RF from peripheral blood in pSS