Half-lives of tetra-, penta-, hexa-, hepta-, and octachlorodibenzo-p-dioxin in rats,monkeys, and humans--a critical review

The elimination half-lives (t1/2) in Sprague-Dawley rats for 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), 1,2, 3,7,8-pentachlorodibenzo-p-dioxin (PeCDD), 1,2,3,4,7,8-hexachlorodibenzo-p-dioxin (HxCDD), 1,2,3,4,6,7,8-heptachlorodibenzo-p-dioxin (HpCDD) and 1,2,3,4,6,7,8,9-octachlorodibenzo-p-dioxin (OCDD) were estimated in long-term studies by Schlatter, Poiger and others. Furthermore, there are some published half-lives of TCDD in adult humans. The average half-life of TCDD in adult humans is approximately 2840 days, while in Sprague-Dawley rats the average t1/2 of TCDD is 19 days. The t1/2 of TCDD in humans is about 150 times that of rats. This factor was used to calculate the t1/2 values of the other polychlorinated dibenzo-p-dioxins (PCDDs) in humans from the rat data. Furthermore, the terminal t1/2 values of PCDDs in adult humans were calculated from the regression equation: logt1/2H = 1.34 logt1/2R + 1.25 which was recently established for 50 xenobiotics (t1/2H = terminal half-lives in days for humans, t1/2R = terminal half-lives in days for rats). The following terminal half-lives in adult humans were obtained: 12.6 years for 1,2,3,7,8-PeCDD, 26-45 years for 1,2,3,4,7,8-HxCDD, 80-102 years for 1,2,3,4,6,7,8-HpCDD and ca. 112-132 years for OCDD. These half-lives of PCDDs are critically compared with measured t1/2 values of PCDDs and other persistent organic pollutants in rats, monkeys and humans.     

An online platform supporting the analysis of water adaptation measures in the Alps

Climate change may result in reduced water supply from the Alps – an important water resource for Europe. This paper presents a multilingual platform that combines spatial and multi-criteria decision-support tools to facilitate stakeholder collaboration in the analysis of water management adaptation options. The platform has an interactive map interface that allows participants to select a location of their interest within the Alpine Arc. By utilising the decision-support tool, stakeholders can identify suitable adaptation solutions for different geographical units, according to their experience and preference. The platform was used to involve experts across Alpine borders, domains and decision-making levels, as well as a group of university students. The experts favoured the planning instruments for saving water, while the students inclined towards the measures that would improve water conservation. The initial results confirmed the suitability of the platform for future involvement of decision-makers in spatio-temporal analyses of adaptation pathways in the Alps.     

The effect of larval and early adult experience on behavioural plasticity of the aphid parasitoid <Emphasis Type="Italic">Aphidius ervi</Emphasis> (Hymenoptera,Braconidae, Aphidiinae)

The relevance of the integration of preimaginal and eclosion experiences on the subsequent habitat preferences and mate finding by the adult has been rarely tested in holometabolous insects. In this work, the effect of larval and early adult experiences on the behavioural responses of adult males of the aphid parasitoid, Aphidius ervi, towards volatiles from the host–plant complex (HPC) and from conspecific females were evaluated. Two experience factors were considered: host diet (normal diet=ND; artificial diet=AD), and eclosion, i.e. extraction or non-extraction of the parasitoid larva from the parasitised aphid (extracted=EX; non-extracted=NE). Thus, four treatments were set up: ND/NE, ND/EX, AD/NE and AD/EX. Glass Y-tube olfactometers were used to investigate the responses of adult A. ervi males to the odour sources used. Males from the ND/NE treatment showed a shorter latency to the first choice of olfactometer arms, displayed a marked preference towards the HPC olfactometer arm, and spent more time in the HPC arm than males from the other treatments. Only the interaction of host diet and eclosion experiences proved to be relevant in explaining the differences in latency to first choice, time spent in olfactometers arms, and behaviours displayed in the olfactometer arms. These results show the importance of the integration of larval and eclosion experiences in the development of stereotyped responses of the adults. This process may involve memory retention from the preimaginal and emergence period, but further research is needed to disentangle the contribution of each stage. The response to conspecific females was much less affected by the treatments in relation to first arm choice and times in olfactometer arms, suggesting a pheromone-mediated behaviour, even though a prompter and more intense wing fanning courtship behaviour was registered in the ND/NE males compared to males from the AD/NE treatment. These results show that sexual behaviours are less affected by early experiences than behaviours related with finding a HPC for foraging or oviposition. Taken together, our results demonstrate for first time that larval and eclosion experiences affect in a differential way the early responses of the adult towards environment-derived cues and mate related cues.     

Ersatz oder Erg?nzung? Schnittstellen zwischen REACH und produktbezogenen Regelungen am Beispiel von Bauprodukten

Hintergrund und Ziel Seit Juni 2007 ist in der EU die neue europ?ische Chemikalienverordnung REACH gültig. Wesentlicher Inhalt der neuen Regelung ist die Einführung eines einheitlichen Systems zur Registrierung, Bewertung, Zulassung und Beschr?nkung von Chemikalien. Die Hersteller/Importeure von Chemikalien müssen wesentliche Angaben zu den inh?renten Stoffeigenschaften vorlegen und die Bedingungen für eine sichere Verwendung der Stoffe über den gesamten Lebenszyklus nennen, d. h. für die Herstellung, Verarbeitung, Nutzung und Entsorgung der Stoffe. Damit birgt REACH das Potenzial von Schnittstellen zu produktbezogenen Regelungen, sofern bei diesen ebenfalls eine Bewertung der enthaltenen oder emittierten Chemikalien erfolgt.     

Beurteilung von Gefahren aus militärischen Altlasten in Einzugsgebieten von Trinkwassergewinnungsanlagen auf der Basis eines Kriterienkataloges

To include consequences emanating from former military sites on the drinking water supply, a catalog of criteria has been developed which permits the determination and assessment of the hazards in general and their impact on human health in particular. The assessment criteria correspond to the special requirements and standards for drinking water hygiene and protection in Germany. The criterion catalog is a completion module to the usual praxis and existing conceptions, and has proved its practical value in the initial assessment of military sites in the new federal states of Germany. The scheme is a control instrument suitable for obtaining an assessment concerning the extent to which drinking-water resources are and will be affected by former waste disposal and other contaminated sites at the present and in the future.     

Release of methane from aerobic soil: an indication of a novel chemical natural process?

Methane (CH₄) formation under aerobic conditions has been intensely debated, especially since the discovery of CH₄ generation by both dried plant material and living plants. In this study we test the hypothesis that non-microbial CH₄ formation also occurs in soils. All lyophilised soil samples investigated under aerobic conditions released CH₄ at temperatures ranging from 30 to 70 °C exceeding that allowing normal enzymatic activity to proceed. No emissions were observed for single mineral soil components such as quartz sand, clay mineral and iron oxide. Methane release rates from the soils investigated were found to increase both with increasing temperature and higher organic carbon content. Addition of water to dried soils increased CH₄ release rates up to 8-fold those observed with the dried material. Our results suggest the existence of a chemical process in soils that produces CH₄ under aerobic conditions, a finding which has not been hitherto reported.     

Metallophyte status of violets of the section Melanium

Violets from metal-enriched soils have controversially been described as both heavy-metal accumulators and excluders in the literature. The present study solves the issue for violets of the section Melanium (zinc violets, Viola lutea ssp. calaminaria and V. lutea ssp. westfalica; hartsease or wild pansy, Viola tricolor; and mountain pansy, V. lutea). The aims were to determine the concentrations of heavy metals in the soil and in the roots and shoots of field-collected plants, to evaluate the potential impact of colonisation by arbuscular mycorrhizal fungi on heavy-metal concentrations in the plant tissues, and to quantitatively define the localisation of the elements in root cross-sections. When these violets grow in low-metal soils, higher concentrations of the heavy metals were found in the roots and shoots than in the soil, whereas the opposite was seen in samples from high-metal soils. Under all field conditions examined, the roots of all of these species were colonised by arbuscular mycorrhizal fungi. However, V. tricolor was marginally colonised when the concentrations of Zn and P were higher in the soil. Determination of the spatial distribution of the elements in root cross-sections of these violets indicates tissue-specific deposition of elements within the vascular tissue, the cortex, and the rhizodermis. These data indicate that violets of the section Melanium are heavy-metal excluders.