Assessment of the indoor Rn contribution of Swiss building materials.
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Air Pollutants, Radioactive↗
Biomedical subjects
W Burkart
Publications and source records attributed to W Burkart.
Adaptive response to 2 low doses of X-rays in human blood lymphocytes.
Human peripheral blood lymphocytes exposed to a single adaptive dose of 1 cGy X-rays or 2 adaptive doses, each of 1 cGy, were found to be equally resistant to the induction of chromosome damage by subsequent challenge with a high dose of 1 Gy X-rays, as compared to cells that were not pre-exposed. They responded with a significantly reduced incidence of chromatid and isochromatid breaks. These results indicate the presence of an inducible chromosomal repair mechanism in human blood lymphocytes and confirm the observations made by earlier investigators. The incidence of chromosome damage was found to be similar in the lymphocytes pre-exposed to a single or 2 adaptive doses, suggesting that, under the conditions tested, the second adaptive dose did not offer any additional protection against the chromosome damage induced by the challenge dose.
Adult↗
Radiation biology of the lung. Recent progress in understanding cancer induction and non-stochastic effects of inhaled radon daughters, hot particles and other radionuclides.
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Animals↗
Resistance and cross-resistance to chromosome damage in human blood lymphocytes adapted to bleomycin.
Human peripheral blood lymphocytes cultured in the presence of low concentrations of bleomycin (BLM), 0.01-0.1 microgram/ml, for 48 h and then treated with a high concentration (1.5 microgram/ml) of the same agent or with 1.5 Gy X-rays, became significantly less sensitive to the induction of chromosomal damage than those which did not receive the pre-treatment with BLM. They responded with lower frequencies of chromatid and isochromatid breaks. These results lend further support to the operation of an adaptive repair system in lymphocytes which offers resistance and cross-resistance to the induction of chromosomal damage by the same or similar DNA-damaging agents.
Adult↗
[Menarche, menstrual cycle and fertility in diabetic patients].
From observations of female type I diabetics, we collected data on menarche, menstrual cycle and fertility. 337 women answered our questionnaire which had been published in journals for diabetic patients. The data were correlated with age, diabetes duration, and the onset of diabetes. The mean age at menarche was inversely correlated with the age of the patients; in diabetics it was 0.8-2 years higher than in the population in which diabetes developed after menarche. As compared to a population of non-diabetics we observed an increase in mean age at menarche of 0.4-1.3 years. The increase was most pronounced if diabetes developed between the age of 3-8 years. The prevalence of primary amenorrhoea in diabetics was 3.6%, in the controls and in diabetics with late onset 1.5%. Irregularities of the menstrual cycle were observed more often in diabetics than in the controls. The prevalences of oligomenorrhoea and secondary amenorrhoea were 14 and 7% in the group of patients with diabetes onset before menarche. In the group with late onset of diabetes the prevalence of secondary amenorrhoea was 12%. Irregularities of the menstrual cycle were found more frequently at the time of diabetes onset, although 76% of the patients had not remarked any change in the frequency of menstrual bleedings. With increasing diabetes duration, the frequency of bleedings normalized. 70.5% of the patients aged 35 or more had spontaneous conceptions, 2.1% were sterile. Both values are not significantly different from the data of the control group.(ABSTRACT TRUNCATED AT 250 WORDS)
Adolescent↗
Effect of 3-aminobenzamide on chromosome damage in human blood lymphocytes adapted to bleomycin.
Human blood lymphocytes, pre-treated with very low (adaptation) concentrations of bleomycin for 48 h and then exposed to a high (challenge) dose of the same agent or X-rays, became significantly less sensitive to the induction of chromosome damage than those which did not receive the pre-treatment, indicating an induction of 'adaptive repair' process. This repair process was negated when 3-amino-benzamide, an inhibitor of poly (ADP) polymerase, was added to the cultures immediately after the challenge treatment. The magnitude of negation in the adaptation response was greater in the case of lymphocytes challenged with X-rays as compared with those challenged with bleomycin.
Adaptation, Biological↗
Influence of subsoil geology and construction technique on indoor air 222Rn levels in 80 houses of the central Swiss Alps.
The indoor 222Rn level depends mainly on the subsoil geology, the cellar floor permeability, the cellar aeration, the air-tightness of the homes, and the aeration habits of the occupants. These five parameters and the 222Rn levels in the cellar and in the living room on the ground floor were compiled in 80 one- or two-family houses of the central Swiss Alps. The 222Rn levels were measured with passive alpha track detectors. Houses located on a granite, ortho-gneiss or verrucano subsoil have a cellar 222Rn level that is on the average 4.4 times higher than houses which are built on grey-schist or sediments. The cellar level is on the average 5.4 times higher if the cellar has partially a gravel or earth floor than if the whole cellar surface is covered with a concrete floor. Energy-efficient, highly air-tightened homes have a living room level that is on the average 1.8 times higher than normally insulated conventional homes. In the cellars and the living rooms of the 80 houses considered, arithmetic mean 222Rn levels of 724 Bq m-3 (20 pCi L-1) and 178 Bq m-3 (4.8 pCi L-1), respectively, were found. In the central Swiss Alps 222Rn and 222Rn decay products lead to an estimated mean exposure of 5.3 mSv effective dose equivalent per year.
Air Pollutants↗
Indoor Rn levels in different geological areas in Switzerland.
The distribution of indoor Rn concentrations in different geological areas in Switzerland was studied using passive alpha-track detectors. Measurements involving a sample of 400 single-family homes were made in the cellar, on the ground floor and the first floor, respectively. On the basis of a pilot survey, the country was divided into four zones in which the Rn distribution in houses was analyzed separately. The indoor exposure to Rn and Rn decay products is quite variable from region to region. The geology of the different areas was found to be an important factor in determining the mean value Rn levels. In the basin north of the Alps, where the population centers are located, a median Rn gas level of 47 Bq m-3 for the living area was found. The arithmetic mean value of 60 Bq m-3 in this region leads to an annual effective dose equivalent of about 1.8 mSv. For the population living in alpine areas, an arithmetic mean value exceeding 200 Bq m-3 will lead to an annual effective dose equivalent in the range of 6 mSv. The estimated exposure to Rn and Rn decay products for the upper one-percentile of the homes in the most affected alpine region even exceeds the annual limit of 50 mSv effective dose equivalent for occupational exposure.
Air Pollutants↗
Increased indoor Rn levels due to actinide containing mineral collections displayed in living areas.
Collection of crystals ranging from quartz to U or Th containing minerals is a widespread spare time activity in Switzerland. Radon emanation from stones displayed in showcases in the living area may contribute considerably to elevated Rn levels in the indoor air. Time-averaged Rn gas measurements in 35 homes of subscribers to a journal for mineral collectors showed an unexpected statistically significant increase of 98 Bq m-3 in the Rn level of the room containing the collections compared to the levels measured in a control room on the same floor. Using ICRP Publication 50 conversion factors for indoor exposure to Rn decay products, the additional effective dose equivalent contracted was estimated to amount to an average of 2.7 mSv y-1. Although the 220Rn emanation rate, as measured in the display cases, was considerable in several cases, the dose from 220Rn decay products in the living area remained always a small fraction of the Rn dose. Remedial actions for crystal collections containing considerable amounts of U- or Th-based minerals are suggested.
Air Pollutants↗
Correlation among the terrestrial gamma radiation, the indoor air 222Rn, and the tap water 222Rn in Switzerland.
The external gamma radiation and the indoor air Rn (222Rn) concentration were measured in 55 houses of the South East Grisons, the Urseren valley, and the Upper Rhine valley (crystalline subsoils) and in 39 houses of the Molasse basin and the Helvetic nappes (sedimentary subsoils). In homes located on a crystalline subsoil, a mean cellar gamma level of 1.40 mGy y-1 was measured, which is twice the mean gamma level of 0.70 mGy y-1 found in homes built on a sedimentary subsoil. The cellar 222Rn gas concentration is about six times higher in houses with a crystalline subsoil (1232 Bq m-3) than in houses with a sedimentary subsoil (201 Bq m-3). Although a weak correlation is observed between the mean gamma radiation levels and mean cellar 222Rn gas concentrations for the five subregions investigated, the gamma levels and the 222Rn gas concentrations do not correlate for single homes. For the population living on the ground floor of a house with a crystalline subsoil, the gamma radiation and the indoor air 222Rn lead to estimated mean exposures of 1.16 mSv and 9.44 mSv effective dose equivalent per year, respectively. In houses with a sedimentary subsoil, these mean exposures lead to 0.68 mSv y-1 and 3.22 mSv y-1, respectively. A mean tap water 222Rn content of 38.3 Bq L-1 and 10.4 Bq L-1 was measured in 31 villages with a crystalline subsoil and 73 villages with a sedimentary subsoil, respectively. Radon-222 degasing from the tap water into the indoor air leads to an additional exposure of about 0.11 mSv y-1 and 0.03 mSv y-1 in homes with a crystalline subsoil and homes with a sedimentary subsoil, respectively.
Air Pollutants↗
Complications and fetal outcome in diabetic pregnancy. Intensified conventional versus insulin pump therapy.
From 1978 to 1986 a total of 189 pregnant diabetic women gave birth at our hospital. In this randomized prospective study the influence of maternal diabetes treatment in normoglycemic patients, continuous subcutaneous insulin infusion (n = 48) versus intensified conventional treatment (n = 41), is evaluated. These two groups of patients are further compared to patients (n = 28) who underwent conventional diabetes treatment during pregnancy. It can be shown from our data that the rate of complications such as preeclampsia, intrauterine growth retardation, premature labor and premature delivery can be reduced by intensified conventional and insulin pump treatment as compared to conventionally treated patients with late onset of pregnancy care. As expected, in the groups of CSII and ICT patients no difference in the rate of pregnancy complications nor in fetal outcome could be demonstrated. Among CSII pregnancies 12/48 were complicated, in the ICT population the respective figure was 13/41 (CT: 20/28). The mean gestational age at the time of delivery ranged between 38 and 40 weeks, depending on the severity of maternal diabetes. CT patients were delivered earlier in all White classes. Fetal morbidity was nearly equal in CSII and ICT children, in CT patients it was greatly enhanced. Also the mortality (perinatal and neonatal) was considerably larger in CT patients (6/28), again, in the CSII and ICT population the mortality was nearly identical (2/48 and 3/41). We conclude, from our prospective information, that insulin pump therapy during pregnancy is indicated if intensified conventional treatment does not lead to normoglycemia.(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
Radon and its decay products in the indoor environment: radiation exposure and risk estimation.
Radon, a member of the uranium decay chains, enters the indoor environment from the building subsoil, walls and the drinking water. In areas with high radium content of rocks and soil, considerable indoor levels of radon are measured. A sample of 32 conventional homes in Southeastern Switzerland, an area with generally high uranium concentrations in the subsoil, showed an arithmetic mean radon concentration in living quarters and cellars of 307 Bq/m3 (8.3 pCi/l) and 1410 Bq/m3 (38.1 pCi/l), respectively. Using UNSCEAR82 conversion factors, the annual effective dose equivalent in this area amounts to 9 mSv (900 mrem). The corresponding dose to the stem cells of the tracheobronchial tissue is about 100 mSv/a (10 rem/a). Life time exposure in such dwellings is in the range of occupational doses collected in modern uranium mines and leading to a significant increase in the lung cancer risk.
Air Pollutants↗
Hot particles in the environment: assessment of dose and health detriment.
Hot particles, highly radioactive particles made up of fission products or actinides and being small enough to become airborne, defy many of the dose models and risk concepts in use by the health physics community. At environmental exposures, both on the level of populations and tissues, dose distributions become very skewed; only few persons or tissue cells being exposed at correspondingly higher levels. Fallout from Chernobyl showed a numerically small subfraction of the aerosol particles containing activities of up to 10 kBq 103-ruthenium or up to 0.3 Bq 242-curium in single particles. The implications of these hot particles on the dosimetry after uptake are great since the locally accumulated dose, for example in the pulmonary region, may reach up to 10 MSv. For inhalation as well as for ingestion, theoretical considerations predict a decrease in the effectiveness of particulate radioactivity as compared to monomeric activity. This hypothesis is also supported by experimental and epidemiological evidence from the examination of the radiation effects of particulate alpha-emitters deposited in the lung.
Accidents↗
Failure of the tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) to inhibit cell-cell coupling in newborn mouse epidermal cells and Chinese hamster V79 cells under non-standard culture conditions.
The function of the skin tumor promoter 12-O-tetradecanoyl-phorbol-13-acetate (TPA) during two-stage carcinogenesis in mice remains obscure because of TPA's numerous phenotypic effects. In vitro studies under established conditions have generated substantial interest in TPA's ability to inhibit, although transiently in some cases, direct cell-cell coupling in several permanent cell lines, by analogy allowing latent 'initiated cells' to escape homeostatic controls in vivo. Using different culture conditions designed to improve the growth of newborn mouse epidermal cells, we examined dye coupling in these cells, and metabolic co-operation in V79 cells, finding no effect of TPA on coupling. It appears that this effect of TPA is overly sensitive to in vitro conditions. Since a corresponding physiological effect has not yet been demonstrated in vivo, future studies should be directed to establish that coupling inhibition by TPA actually does occur and plays some role during tumor promotion in vivo, and is not merely a characteristic of certain culture systems.
Animals↗
Severe coughing during captopril and enalapril therapy.
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Captopril↗
[Radiation exposure and risk of radon in the room air of Swiss houses].
The radioactive noble gas radon, a member of the natural decay chains of uranium and thorium, enters the indoor environment in regionally highly diverging amounts. Subsoil of dwellings, building materials and drinking water are the main sources. In Switzerland and in many other countries, exposure of the lung tissue to the short lived radon decay products is the most important component of the radiation dose of the general public. Annual doses in areas with crystalline rock of high uranium content may reach the limits set up for occupational exposure. However, a clear link between cumulative exposure to radon daughters and elevation of the lung cancer incidence exists only for underground miners. The majority of human epidemiological studies point to a linear dose effect relationship. The indoor radon levels are determined by geology, building materials and techniques, climate and behaviour of the occupants. Experiences from Scandinavia and the Northern parts of America clearly indicate the possibility of cost-efficient remedial measures to reduce indoor radon levels.
Air Pollution, Radioactive↗
Effects of alloxan-induced diabetes mellitus on the metabolism of the rat placenta.
Biochemical changes in the placenta were studied using alloxan-induced diabetes mellitus in the female rat. In comparison with a control group (n = 13) the placentas of the diabetic animals (n = 12) had significantly higher glucose, glycogen and protein levels. It was, however, shown that this supply of substrate was inadequately utilised for energy, as ATP/ADP quotient was lower and the ADP content was significantly higher. Metabolism still appeared to take place under aerobic conditions, as evidenced by the unchanged lactate levels. In terms of the protein content of the placentas, the activity of the enzymes we investigated (GOT, GPT, LDH, G-6-PDH, MDH, ICDH) was lowered by 25-44%. These results support the idea of global placental insufficiency in diabetics.
Adenosine Diphosphate↗
Antenatal assessment of fetal outcome in pregnant diabetics.
The predictive value of three parameters (amniotic fluid insulin and C-peptide, and HbA1) in prognosticating major neonatal symptomatology was investigated in 57 pregnancies of diabetic women. The prediction of a healthy neonate can be achieved with a 90% accuracy by measurement of the amniotic fluid insulin alone. The correct prognosis for a child with major neonatal problems due to maternal diabetes can be made with 70% certainty using the same method. All other parameters can be judged less valuable based on our results. By using more than one of those parameters mentioned, the prediction of a healthy child can be made more correctly with a certainty of almost 100%. The accuracy in predicting a child with major symptoms cannot be increased any further.
Amniotic Fluid↗