Auftreten von PCDD/PCDF in Brandfällen

Over the last years, polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/PCDF) have been identified in the soot of various accidental fires at concentrations which have made an extensive reconstruction of the buildings necessary. In these cases, dioxin precursors like polychlorinated biphenyls (PCB) or large amounts of other halogenated organic compounds like PCV cable coatings were involved. Dependent on the circumstances of the fire and the materials burnt, the levels of contamination and the congener pattern of the PCDD/PCDF in the soot were different. The analytical results from various accidental fires were evaluated and compared with laboratory data. A hierarchical cluster analysis supports the interpretation of the data and shows that the contamination of the soot from the fire in the Düsseldorf Airport in April 1996 was a mixed contamination primarily caused by PCB and PVC.     

Challenges in non-invasive prenatal screening for sub-chromosomal copy number variations using cell-free DNA

Non-invasive prenatal screening (NIPS) has revolutionized the approach to prenatal fetal aneuploidy screening. Many commercial providers now offer analyses for sub-chromosomal copy number variations (CNVs). Here, we review the use of NIPS in the context of screening for microdeletions and microduplications, issues surrounding the choice of disorders tested for, and the advantages and disadvantages associated with the inclusion of microdeletions to current NIPS. Several studies have claimed benefits; however, we suggest that microdeletions have not demonstrated a low enough false positive rate to be deemed practical or ethically acceptable, especially considering their low positive predictive values. Because a positive NIPS result should be confirmed using diagnostic techniques, and false positive rates are as high as 90% for some microdeletions, diagnostic testing seems preferable when the goal is to maximize the detection of microdeletion or microduplication syndromes.     

An Edge Effect Caused by Adult Corn-Rootworm Beetles on Sunflowers in Tallgrass Prairie Remnants

Abstract: The once-extensive tallgrass prairie community of North America has been reduced to small remnants, many of which are surrounded by intensive corn (   Zea mays ) agriculture. We investigated adult corn-rootworm beetles (Chrysomelidae : Diabrotica spp.), important pests of corn, on sunflowers (Asteraceae : Helianthus spp . ) in prairie remnants in southeast Minnesota. Large numbers of beetles invaded the prairie from surrounding corn fields in late summer. D. barberi and D. virgifera were captured on sticky traps in all locations in the prairie, but abundance was much greater near the edge adjacent to corn. We observed D. barberi ( but not D. virgifera ) feeding extensively on sunflower pollen and occasionally on other flower parts, such as petals. Sunflowers located nearer corn fields sustained more floral damage than those farther from corn. To determine the effect of beetle damage on seed set, we enclosed sunflower heads in bags with either zero, two, or four D. barberi adults. Seed set was reduced in heads enclosed with D. barberi . Thus, this agricultural pest may interfere with the successful reproduction of sunflowers and possibly other prairie composites that flower in late summer. Given the small size of most prairie remnants and the abundance of this flower-feeding beetle in landscapes dominated by corn agriculture, D. barberi may affect the sustainability of prairie plant populations.     

Hydrological and geochemical factors affecting leachate composition in municipal solid waste incinerator bottom ash: Part I: The hydrology of Landfill Lostorf, Switzerland

The objective of the investigation of the municipal solid waste incinerator (MSWI) bottom ash landfill, Landfill Lostorf, was to determine the residence time of water in the landfill and the flow paths through the landfill. Over a period of 22 months, measurements of rainfall, landfill discharge and leachate electrical conductivity were recorded and tracer experiments made. Over the yearly period 1995, approximately 50% of the incident rainfall was measured in the discharge. An analysis of single rain events showed that in winter, 90–100% of rainfall was expressed in the landfill discharge, whereas in summer months, the value was between 9 and 40% depending on the intensity of the rain event. The response to rainfall was rapid. Within 30–100 h, approximately 50% of water discharged in response to a rain event had left the landfill. The discharge was less than 4 l/min for approximately 50% of the measurement periods. Qualitative tracer studies with fluorescein, pyranine and iodide clearly showed the existence of preferential flow paths. This was further substantiated by quantitative tracer studies of single rain events using / ratios and electrical conductivity measurements. The proportion of rainwater passing directly through the landfill was found to be between 20 and 80% in summer months and around 10% in winter months. The difference has been ascribed to the water content in the landfill. The average residence time of the water within the landfill has been estimated to be roughly 3 years and this water is the predominant component in the discharge over a yearly period.     

Elimination kinetics of perfluorohexanoic acid in humans and comparison with mouse,rat and monkey

Major fluorinated chemical manufacturers have developed new short-chain per- and polyfluorinated substances with more favorable environmental, health and safety profiles. This study provides the first evaluation of the elimination half-life of perfluorohexanoic acid (PFHxA) from the blood of humans. PFHxA biomonitoring data were obtained from a recently published study of professional ski wax technicians. These data were analyzed to provide estimates of the apparent half-life of PFHxA from humans, and comparisons were made with kinetic studies of PFHxA elimination from mice, rats and monkeys. The apparent elimination half-life of PFHxA in highly exposed humans ranged between 14 and 49 d with a geomean of 32 d. The half-lives of PFHxA in mice, rats, monkeys and humans were proportional to body weight with no differences observed between genders, indicating similar volumes of distribution and similar elimination mechanisms among mammalian species. Compared to long-chain perfluoroalkyl acid analogs, PFHxA is rapidly cleared from biota. The consistent weight-normalized elimination half-lives for PFHxA in mammalian species indicates that results obtained from animal models are suitable for establishment of PFHxA benchmark dose and reference dose hazard endpoints for use in human risk assessments.     

Implementing the UNCCD: Participatory challenges

The United Nations Convention to Combat Desertification (UNCCD) emphasizes the need for public participation in land degradation assessment and rehabilitation. While participatory approaches are supported by a growing body of research and practice, meaningfully involving the people affected by land degradation is far from straightforward. This paper investigates the challenge of using the UNCCD as a guide to influence community participation in policy‐making and practice at national and local levels by analyzing experiences from three southern African countries. We show that the UNCCD represents a useful normative framework for addressing degradation problems, but that the participatory ethos is difficult to enact at the national level. Whilst there is increasing evidence that combining local and scientific knowledge using participatory mechanisms can deliver the benefits that the Convention strives to achieve, communication between researchers and practitioners, and those involved in implementing the UNCCD at the national level needs to be strengthened. Broad lessons and best practices in incorporating participatory practices into policy development are elucidated. Our case studies show that a range of mixed‐method, interdisciplinary approaches can enable policy‐makers and practitioners to meaningfully engage those who are affected by land degradation in its definition, assessment and rehabilitation.