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Biomedical subjects

P Stegnar

Publications and source records attributed to P Stegnar.

16 recordsLinked to original sources
PubMed2000

Mercury, selenium, and cadmium in human autopsy samples from Idrija residents and mercury mine workers.

Total Hg and Se concentrations were determined in autopsy samples of retired Idrija mercury mine workers, Idrija residents living in a Hg-contaminated environment, and a control group with no known Hg exposure from the environment. In selected samples we also checked the presence of MeHg. The highest Hg concentrations were found in endocrine glands and kidney cortex, regardless of the group. MeHg contributed only to a negligible degree to the total mercury concentrations in all analyzed samples. In the Hg-exposed groups the coaccumulation and retention of mercury and selenium was confirmed. Selenium coaccumulation with a Hg/Se molar ratio near 1 or higher was notable only in those tissue samples (thyroid, pituitary, kidney cortex, nucleus dentatus) where the mercury concentrations were >1 microg/g. After tissue separation of such samples the majority of these elements were found in the cell pellet. Because the general population is continuously exposed to Cd and possibly also to Pb from water, food, and/or air, in some samples the levels of these elements were also followed. In all examined control tissue samples the average values of Cd (kidney cortex, thyroid, hippocampus, cortex cerebellum, nucleus dentatus) and Pb (thyroid, hippocampus) exceeded the average values of Hg. Cd concentrations were the highest, particularly in kidney cortex and thyroids (microg/g), but no relationship between Cd and Se concentration was evident at the tissue level. Regarding the results in the control group, it is debatable which element is the more hazardous for the general population as concerns neurotoxicity.

Adult↗
PubMed1996

The evaluation of waste, surface and ground water quality using the Allium test procedure.

The bulbs of Allium cepa were grown in test liquids of various pollution levels as follows: undiluted industrial and municipal waste water; biological treatment plant output water; water from the Drava river upstream and downstream of the city of Maribor; and non-chlorinated drinking water as a negative control test. The paper presents the response of the Allium cepa genetic material to the presence of potential cytotoxic and genotoxic substances in test liquids and the suitability of the Allium cepa testing procedure as a method for short-term determination of water pollution level. The suitability of the Allium test procedure as a system for environmental monitoring is presented. The influence of water pollution on macroscopic and cytologic parameters of the common onion by application of the biological testing method was examined. The macroscopic parameter was inhibition of root growth. The cytological parameters were: aberrant cells in metaphase and anaphase, index of micronuclei appearance and inhibition of cell division. The possibility of categorization the different polluted test liquids into quality classes is presented according to the influence of the test liquids on macroscopic and cytologic parameters. Test liquids are divided into 8 quality classes: the first class is the least polluted surface waters, the second and the third classes are more polluted surface water, the fourth and the fifth classes are biological treatment plant output waters, the sixth till the eighth quality classes are untreated waste waters. The most polluted test liquids (untreated industrial and municipal waste waters) caused sublethal and even lethal effects. The most polluted tested liquids cause the inhibition of root growth over 50% (even up to 74%), decrease of mitotic index over 36% (even up to 66%), increase of presence of interphase cells with micronuclei over 3% and increase of presence of aberrant cells for more than 10 times in comparison to control test.

Allium↗
PubMed1995

Dietary mercury intake and human exposure in an Adriatic population.

A study was conducted to examine human exposure to mercury through dietary mercury intake in a population living in an industrially non-polluted area of the Adriatic Sea. The results have shown that approximately 20% of the subjects had a weekly dietary mercury intake above the provisional tolerable weekly intake (PTWI), primarily those consuming fish and other seafood > 6 times/week. The estimated seafood consumption corresponding to a mean intake of PTWI of 300 micrograms total mercury was 1559 g, and 1365 g for a PTWI of 200 micrograms methylmercury. However, the total mercury content in hair in individuals consuming total mercury above the PTWI was in the range of 1.3-12.9 micrograms/g, whereas the methylmercury content in hair in subjects consuming methylmercury above the PTWI was between 1.1-10.8 micrograms. Thus, the mercury content in hair did not reach the critical level at which toxic effects of mercury could be expected. The results, particularly those related to methylmercury exposure, did not differ significantly from data reported earlier from an industrially polluted area, thus indicating that the mercury content of fish and consequent human exposure to mercury reflects primarily the general ecological characteristics of the Adriatic, rather than the impact upon a specific local pollution.

Adolescent↗
PubMed1994

Mercury toxicokinetics in Wistar rats exposed to elemental mercury vapour: modeling and computer simulation.

The kinetics of total mercury (Hg) absorption, distribution and elimination in Wistar rats exposed for long periods to elemental mercury vapour (Hg zero) in the Idrija mercury mine were studied. From the experimental data base a compartmental model was built as a framework for experimental data interpretation and prediction of organ mercury levels under different conditions. Using the model the exposures of rats under conditions comparable to those of professionally exposed workers (mercury miners, workers in the chloralkali industry) and individuals with amalgam fillings were simulated.

Animals↗
PubMed1994

Systematic indoor radon and gamma measurements in kindergartens and play schools in Slovenia.

Systematic measurements of indoor radon concentrations and gamma dose rates were carried out in the 730 kindergartens and play schools in Slovenia that, together, care for 65,600 children. The main method for indoor radon measurement was direct sampling in alpha scintillation cells, but in cases with an increased instantaneous radon concentration, the additional methods of track-etch detectors and alpha spectroscopy were applied. In 528 kindergartens and play schools (72%), radon concentrations were below 100 Bq m-3, with a geometric mean of 58 Bq m-3. In 16 kindergartens and play schools (2.2%), radon concentrations exceeded 800 Bq m-3. In all cases, the main reason for a high indoor radon concentration was the geological structure of the soil. Gamma dose rates were measured with a portable scintillation counter, but in the Ljubljana region thermoluminescence dosimeters were also exposed. The results ranged from 30 to 295 nGy h-1, with a geometric mean of 88 nGy h-1.

Air Pollution, Indoor↗
PubMed1993

Interactions of mercury in rat brain.

In order to study the metabolism of mercury (Hg), its affinity to metallothionein (MT), and its influence on levels of the essential metals copper and zinc in the brain tissue of rats exposed to elemental mercury (HgO) vapor was investigated. The major findings were: 1. After long-term exposure, about 40% of mercury was found in the brain water-soluble phase (supernatant); 2. In brain supernatant, about 80% of Hg was found in the range of low-molecular-weight proteins; the MT-like protein Hg-Cu-Zn-thionein was isolated and partially characterized; 3. HgO vapor exposure resulted in increased tissue levels of essential Cu and Zn in addition to exogenous Hg; and 4. Experiments showed that HgO vapor exposure can induce the stimulation of rat brain MT synthesis.

Animals↗
PubMed1992

A survey of lymphocyte chromosomal damage in Slovenian workers exposed to occupational clastogens.

Assays for sister-chromatid exchanges (SCE), unstable chromosome and chromatid aberrations and micronuclei were performed on blood lymphocytes from persons exposed protractedly to radiation or chemical hazards in the workplace. There was a general tendency with all endpoints examined for the yields to increase with years of working in the industry. This was especially marked for SCE. By comparison with a control group of administrative workers the levels of damage were higher, usually significantly so, in the occupational groups. These comprised workers at a nuclear research reactor, a hospital diagnostic X-ray department, a coal mine and a mercury ore mine.

Adult↗
PubMed1992

Rapid radiochemical neutron activation analysis for iodine in urine by different separation techniques.

In the present work on radiochemical neutron activation analysis for the determination of iodine in urine samples, the performance of three different radiochemical separation techniques, namely, direct extraction, use of an iodinated ion-exchange resin column and Schöniger combustion, were intercompared and validated. The practical advantages of the iodinated-resin technique make it most suitable for the rapid routine determination of iodine in urine. It was further verified by participation in an international intercomparison run of urine analysis, and used in a pilot study on iodine determination in the urine of 171 Slovenian schoolchildren, where it gave results in good agreement with the catalytic method.

Child↗
PubMed1992

Investigation of mercury speciation in lichens.

Epiphytic lichens have long been considered to be reliable bioindicators of air pollution. In the present study only one lichen species, Hypogymnia physodes (L.) Nyl., was chosen; this species is very often used for biomonitoring in Europe. Total mercury and methylmercury were determined in lichens taken from various polluted and unpolluted locations in Slovenia, including a mercury mining area around Idrija. Additionally, total gaseous mercury in air was also determined at several sampling points.

Air Pollutants↗
PubMed1991

Chromosome aberrations induced in human lymphocytes by U-235 fission neutrons: I. Irradiation of human blood samples in the "dry cell" of the TRIGA Mark II nuclear reactor.

A set-up for irradiation of biological samples in the TRIGA Mark II research reactor in Ljubljana is described. Threshold activation detectors were used for characterisation of the neutron flux, and the accompanying gamma dose was measured by TLDs. Human peripheral blood samples were irradiated "in vitro" and biological effects evaluated according to the unstable chromosomal aberrations induced. Biological effects of two types of cultivation of irradiated blood samples, the first immediately after irradiation and the second after 96 h storage, were studied. A significant difference in the incidence of chromosomal aberrations between these two types of samples was obtained, while our dose-response curve fitting coefficients alpha 1 = (7.71 +/- 0.09) x 10(-2) Gy-1 (immediate cultivation) and alpha 2 = (11.03 +/- 0.08) x 10(-2) Gy-1 (96 h delayed cultivation) are in both cases lower than could be found in the literature.

Chromosome Aberrations↗
PubMed1988

Atmospheric radon concentrations in dwellings in Slovenia, Yugoslavia.

About 120 homes in Slovenia, Yugoslavia, were selected in urban areas, in a uranium rain and mill region, around coal-fired plants and around a phosphate mill. Radon-222 in air was determined using alpha scintillation cells and the gamma dose rate measured with thermoluminescent dosimeters. The levels obtained were explained by differences in building materials and ventilation rates of homes, as well as by the influence of man-made radioactivity sources. The results show that in the same region radon concentration, expressed as geometric mean, can be up to eight times higher in winter than in the autumn (Pohorje) or nine times higher in one region relative to another (Zirovski vrh-Zasavje).

Air Pollutants↗
PubMed1975

The occurrence of mercury in amphibia.

Studies have been made of the distribution of mercury and its occurrence as methylmercury in the organs of amphibia collected from different sites mainly in Slovenia, Yugoslavia, including the area around the mercury mine at Idrija. Liver accumulates the highest amounts of mercury, up to 2 ppm in apparent background areas, with values up to 0.5 ppm in muscle, where virtually all mercury is present in the methyl form. Results are reported for some other trace elements in liver. Amphibia may provide useful monitors of the occurrence and spread of mercury contamination.

Amphibians↗
PubMedDate not supplied

Chromium-induced micronuclei in fish.

An investigation of the cytogenetic effects of chromium (Cr(VI) and Cr(III)) in Prussian carp (Carassius auratus gibelio) was made. For detecting cytogenetic damage, micronuclei induction in fish erythrocyte cells was employed. Fish were investigated 100 m above and 400 m below the discharge of leather waste products into the river Ljubljanica, and by exposing fish to three doses of chromium (Cr(VI) and Cr(III)) in the laboratory. The exposure of fish to various concentration levels (sub-lethal) of chromium under laboratory and field conditions caused an increase in the frequency of micronuclei compared with the control groups.

Animals↗
PubMedDate not supplied

Determination of trace elements in standard reference materials by the ko-standardization method.

The ko-standardization method is suitable for routine multielement determinations by reactor neutron activation analysis (NAA). Investigation of NIST standard reference materials SRM 1571 Orchard Leaves, SRM 1572 Citrus Leaves, and SRM 1573 Tomato Leaves showed the systematic error of 12 certified elements determined to be less than 8%. Thirty-four elements were determined in NIST proposed SRM 1515 Apple Leaves.

Neutron Activation Analysis↗