Rapid breakthrough of 131I in an in vitro human epidermis model.

Skin contamination with radionuclides may cause local radiation damage, but also systemic distribution if the nuclides penetrate the epidermal membrane. Detailed information of the skin absorption of radionuclides is of importance for e.g. dose estimations and development of decontamination strategies. In the present study, penetration of 131I through human epidermis was studied using an in vitro flow through diffusion chamber. Epidermis was exposed to a Na131I-solution, used in nuclear medicine, and the potential concentration-dependency of skin penetration was examined by including two concentrations of non-radioactive NaI. Penetration of 131I occurred after a few minutes of exposure and steady state penetration rate was obtained after about 50-70min independently of the iodine concentration and receptor solution used. The two receptor solutions evaluated; phosphate buffered saline solution and an ethanol and water-mixture (1:1), resulted in significantly higher penetration rate of 131I using the ethanol and water-mixture. The penetration of iodine was calculated to be concentration-dependent independently of the receptor solution utilized. In addition, radioactive iodine did not accumulate in epidermis in the in vitro-model used. In conclusion, the present study provides detailed information on the rapid iodine penetration at the early phase of radionuclide exposure, defined as the first 30min of the experiment, and is clearly suitable for decontamination studies. In addition, methodological aspects, e.g. impact of the receptor solution, should carefully be considered in studies of radionuclide skin penetration using in vitro-techniques.

Handling interferences in 89Sr and 9°Sr measurements of reactor coolant water: a method based on strontium separation chemistry.

Measurements for determining the activity of (89)Sr and (90)Sr in reactor coolant water are associated with limitations due to interferences from radionuclides with similar chemical properties and ß(-)-energies. From a measurement bias point-of-view these interferences would result mainly in an overestimated activity concentration of (90)Sr. In order to address the interference problem, a common and well-known method was used in order to show the need for sufficient decontamination. An improvement was achieved by taking the sample through two initial strontium separations in order to increase the decontamination factor. This method determines the activity concentration of (89)Sr and (90)Sr, via its daughter nuclide (90)Y, by Cherenkov counting. This work is primarily based on theoretical calculations of strontium-, yttrium- and other potential interfering radionuclide ratios after instant fission. The work done to confirm the theoretical calculations were carried through on spiked strontium standard solutions and fresh reactor coolant water. The reactor coolant water was known to contain interferences at a composition resembling that of instant fission. The detection limit for double separation was calculated to 0.17 Bq/kg for (90)Sr and 0.38 Bq/kg for (89)Sr. When using methods that solely rely on strontium resins, this paper shows that the decontamination factor (DF) is significantly higher when using double separation than that of a single separation. The paper also shows that the DF of an initial double strontium separation is as effective when it comes to removing high ratio interferences as separations done with both Sr- and Ln-resin (EiChrom Technologies, Inc., 2003; Tovedal et al., 2009b). However, 'old' samples, where e.g. (140)Ba and (89)Sr has decayed, does not benefit from double separation. Furthermore, samples with low ratios of interfering radionuclides does not benefit from using this method either, seeing as this is a more time consuming method due to the double separations.

240Pu/239Pu mass ratio in environmental samples in Finland.

The (240)Pu/(239)Pu mass ratio was determined with SF-ICP-MS in lichen, peat, grass, air filter, and hot particle samples obtained in Finland. The main part of the air filters were sampled in northern Finland in 1963, whereas all the other samples were collected in southern and central Finland immediately after the Chernobyl accident in 1986. The (240)Pu/(239)Pu mass ratio varied between 0.13 ± 0.01 and 0.53 ± 0.03 in the environmental samples analyzed. The values for the (240)Pu/(239)Pu ratio confirm previous estimations, based on the (238)Pu/(239+240)Pu alpha activity ratio in the same samples, that global fallout from nuclear weapons testing and deposition from the Chernobyl accident have been the main Pu contamination sources in the environment in Finland.

Reasons among older Swedish women of not participating in a food survey.

OBJECTIVES: To (a) examine participation rate as a function of municipality, age group and living status; and (b) investigate the main reasons for exclusion and declining as stated by the women themselves. DESIGN: Analysis of participation rate and content analysis of statements given in phone calls explaining exclusion or declination from a project in which 24 h recalls and food-diaries were used. SUBJECTS: Self-managing Swedish women (n=505) were systematically selected from a stratified random sample covering single living and cohabiting women aged 64-68, 74-78 and 84-88 y living in three municipalities. RESULTS: No significant differences were found among included and declining women when municipalities and living status was analysed, but significantly more women in the oldest group were excluded (P>0.01). Among those in their 80s living at home, the usual reasons for exclusion were illness, disability or dementia, and many lived in institutions for old people. The four most used explanations to decline participation were 'lack of time', 'tired, fragile, sick or having bad memory', 'not willing to participate in scientific studies' and 'too old and nothing to contribute'. CONCLUSIONS: The participation rate was, compared with other food surveys in the older generation, fairly good, especially among those in their 80s. However, the most active and the very ill and disabled did not participate. SPONSORSHIP: The Swedish Council for Social Research, the Swedish Council for Forestry and Agricultural Research, the Swedish Foundation for Health and Care Sciences and Allergy Research and Uppsala University.

Qualitative analysis of the questions raised by patients with gynecologic cancers and their relatives in an educational support group.

BACKGROUND: People's knowledge of cancer is generally inadequate to help them cope with a diagnosis of cancer. Educational support groups may allow cancer patients to receive information they want that is normally not covered in the individual clinical encounter. It was desired to identify the content of such information as reflected in the questions asked by cancer patients and their relatives in such support groups. METHOD: The 329 questions asked by 41 patients and 11 of their relatives in 40 group sessions were analyzed and categorized. RESULTS: The categories found are described. Almost 100 questions could be allocated to the category "the illness," of which the most common was, "Is cancer hereditary?" The questions made it clear that the patients had a wish and a need to understand cancer. CONCLUSION: An educational support group provides a complement to, and not a substitute for, the clinical provision of medical information.

A hydrological tracer study of water uptake depth in a Scots pine forest under two different water regimes.

Little is known about the vertical distribution of water uptake by trees under different water supply regimes, the subject of this study, conducted in a Scots pine stand on sandy loam in northern Sweden. The objective was to determine the water uptake distribution in pines under two different water regimes, desiccation (no precipitation) and irrigation (2 mm day-1 in July and 1 mm day-1 in August), and to relate the uptake to water content, root and soil texture distributions. The natural 18O gradient in soil water was exploited, in combination with two added tracers, 2H at 10 cm and 3H at 20 cm depth. Extraction of xylem sap and water from the soil profile then enabled evaluation of relative water uptake from four different soil depths (humus layer, 0-10, 10-25 and 25-55 cm) in each of two 50-m2 plots per treatment. In addition, water content, root biomass and soil texture were determined. There were differences in vertical water uptake distribution between treatments. In July, the pines at the irrigated and desiccated plots took up 50% and 30%, respectively, of their water from the upper layers, down to 25 cm depth. In August, the pines on the irrigated plots took up a greater proportion of their water from layers below 25 cm deep than they did in July. In a linear regression, the mean hydraulic conductivity for each mineral soil horizon explained a large part of the variation in relative water uptake. No systematic variation in the residual water uptake correlated to the root distribution. It was therefore concluded that the distribution of water uptake by the pines at Åheden was not a function of root density in the mineral soil, but was largely determined by the unsaturated hydraulic conductivity.