Person: Konietzka, Rainer
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Veröffentlichung Gastrointestinal absorption of uranium compounds A review(2015) Konietzka, RainerUranium occurs naturally in soil and rocks, and therefore where it is present in water-soluble form it also occurs naturally in groundwater as well as in drinking water obtained from groundwater. Animal studies suggest that the toxicity of uranium is mainly due to its damage to kidney tubular cells following exposure to soluble uranium compounds. The assessments of the absorption of uranium via the gastrointestinal tract vary, and this has consequences for regulation, in particular the derivation of e.g. drinking water limit values. Absorption rates vary according to the nature and solubility of the compound in which uranium is presented to the test animals and depending on the animal species used in the test. No differences for sex have been observed for absorption in either animals or humans. However, human biomonitoring data do show that boys excrete significantly more uranium than girls. In animal studies neonates took up more uranium than adults or older children. Nutritional status, and in particular the iron content of the diet, have a marked influence on absorption, and higher uranium levels in food intake also appear to increase the absorption rate. If the pointers to an absorption mechanism competing with iron are correct, these mechanisms could also explain the relatively high concentration and chemical toxicity of uranium in the kidneys. It is here (and in the duodenum) that divalent metal transporter 1 (DMT1), which is primarily responsible for the passage of iron (or uranium?) through the cell membranes, is most strongly expressed.Quelle: http://www.sciencedirect.comVeröffentlichung Significance thresholds for the assessment of contaminated groundwater: perfluorinated and polyfluorinated chemicals(2018) von der Trenck, Karl Theo; Biegel-Engler, Annegret; Konietzka, RainerBackground Per- and polyfluorinated chemicals (PFC) do not occur naturally in the environment and are, therefore, of anthropogenic origin. As a consequence of their wide range of everyday applications and their extreme persistence in the environment, PFC have become ubiquitous in nature and can, therefore, be detected in groundwater as well as in many other environmental matrices. The German States' Water and Soil Consortia have compiled 'significance thresholds' (GFS) to assess groundwater contaminated with PFC. The GFS serve as criteria for the decision whether actions to remediate polluted groundwater are necessary. Thirteen of these PFC had been detected in groundwater at levels above their limit of quantitation and were assigned first priority. Results The data regarding human health effects were sufficient to derive guide values according to the criteria of the German Drinking Water Ordinance for 7 of the 13 first-priority PFC. With regard to available ecotoxicological data, predicted no-effect concentration values from official risk assessments existed for 2 of the 13 first-priority PFC. A predicted no-effect concentration for protection of the aquatic biocenosis could be derived for eight more substances. Conclusions After evaluation of data from available literature regarding both human health and ecotoxicological effects, significance thresholds ranging from 0.06 to 10.0 ng/L could be derived for 7 of the 13 priority PFC in groundwater. As a practical guide valid solely for human health-based values, a summation rule was proposed for exposures to mixtures of these seven PFC.Veröffentlichung Rund um das Trinkwasser(2016) Bartel, Hartmut; Dieter, Hermann H.; Feuerpfeil, Irmgard; Grummt, Hans-Jürgen; Grummt, Tamara; Hummel, Annette; Konietzka, Rainer; Rapp, Thomas; Rechenberg, Jörg; Schaefer, Benedikt; Vigelahn, Lothar; Deutschland. UmweltbundesamtVeröffentlichung Dioxine und dioxinähnliche PCB in Umwelt und Nahrungsketten(2013) Behnke, Anja; Blondzik, Katrin; Böhnhardt, Anna; Bussian, Bernd M.; Dauert, Ute; Gärtner, Philipp; Giese, Evelyn; Juhrich, Kristina; Knetsch, Gerlinde; Konietzka, Rainer; Minkos, Andrea; Plickert, Sebastian; Rappolder, Marianne; Schmidt, Simone; Schröter-Kermani, Christa; Utermann, Jens; Deutschland. UmweltbundesamtVeröffentlichung Dioxine und dioxinähnliche PCB in Umwelt und Nahrungsketten(2017) Behnke, Anja; Blondzik, Katrin; Böhnhardt, Anna; Bussian, Bernd M.; Dauert, Ute; Fettig, Ina; Gärtner, Philipp; Giese, Evelyn; Juhrich, Kristina; Knetsch, Gerlinde; Konietzka, Rainer; Koschorreck, Jan; Markard, Christiane; Minkos, Andrea; Moriske, Heinz-Jörn; Plickert, Sebastian; Rappolder, Marianne; Schmidt, Simone; Schröter-Kermani, Christa; Utermann, Jens; Deutschland. UmweltbundesamtDioxine und dioxinähnliche polychlorierte Biphenyle (dl-PCB) gehören zu den gefährlichsten Umweltgiften. Obwohl die Dioxin-Emissionen seit 1990 in Deutschland und Europa deutlich verringert und der Einsatz von PCB 1989 verboten wurde, kommen Dioxine und PCB aufgrund ihrer Langlebigkeit noch immer in der Luft, im Boden oder in Gewässersedimenten vor und gelangen so in die Nahrungskette von Tier und Mensch. Um das zu vermeiden, ist es notwendig, alle Quellen aufzuspüren und die Belastungen der Umwelt weiter zu minimieren. Das aktualisierte Hintergrundpapier des Umweltbundesamtes informiert ausführlich über die Zusammenhänge zwischen der Belastung von Umwelt und tierischen Nahrungsmitteln durch Dioxine und dl-PCB - von der Entstehung über den Transfer in die Nahrungsketten bis zu den Wirkungen auf den Menschen. Quelle: https://www.umweltbundesamt.deVeröffentlichung Dioxine und dioxinähnliche PCB in Umwelt und Nahrungsketten(2013) Behnke, Anja; Blondzik, Katrin; Böhnhardt, Anna; Bussian, Bernd M.; Dauert, Ute; Gärtner, Philipp; Giese, Evelyn; Juhrich, Kristina; Knetsch, Gerlinde; Konietzka, Rainer; Minkos, Andrea; Plickert, Sebastian; Rappolder, Marianne; Schmidt, Simone; Schröter-Kermani, Christa; Utermann, Jens; Deutschland. UmweltbundesamtVeröffentlichung The ex-vivo intestinal absorption rate of uranium is a two-phase function of supply(2014) Konietzka, RainerThe concentration-dependent absorption behaviour of uranium was investigated with surviving intestinal segments of rat jejunums, using an ex-vivo model. The results showed a monotonic slightly nonlinear increase in absorption as uranium concentrations increased. This trend was observed over the entire concentration range tested. In the lower concentration range a slower linear ascent was observed while a steeper linear ascent was found for the higher concentration range. Statistical fit was only slightly poorer for an exponential function in the range of lower values and a logarithmic function in the range of higher values. The proportion of uranium absorbed expressed as percent of uranium concentrations in the perfusion solutions followed a monotonically increasing trend from 20 to around 200 ìg/l uranium in the perfusion solutions, which thereafter appears to reach a plateau, as further increase towards concentrations around 400 ìg/l is not substantial. The uranium concentration administered had no effect on the vitality and consequently the functionality of the intestinal segments, measured in terms of active glucose transport. The results imply that uranium concentrations of more than 20 ìg/l in drinking water, for example, could lead to elevated absorption rates and thus to higher internal exposures to consider when setting of Guideline values in this concentration range.Quelle: http://www.sciencedirect.comVeröffentlichung Rund um das Trinkwasser(2016) Bartel, Hartmut; Dieter, Hermann H.; Feuerpfeil, Irmgard; Grummt, Hans-Jürgen; Grummt, Tamara; Hummel, Annette; Konietzka, Rainer; Rapp, Thomas; Rechenberg, Jörg; Schaefer, Benedikt; Vigelahn, Lothar; Deutschland. UmweltbundesamtWelche Qualität hat das Leitungswasser in Deutschland? Wie wird es kontrolliert? Wie sieht es mit Nitrat, Blei oder Krankheitserregern aus? Was ist bei den Trinkwasserinstallationen im eigenen Haus zu beachten? All das und mehr erfahren Sie in unserem Ratgeber. Quelle: Umweltbundesamt