Uptake by foods of tetrachloroethylene, trichloroethylene, toluene, and benzene from air

Summary Transition rates from air into foods as well as equilibrium concentrations in air and critical foods were determined for tetrachloroethylene, trichloroethylene, benzene and toluene. From these data, maximum concentrations of the four substances in air were estimated that keep contamination of critical foods at an acceptable level. A simple and rapid method allowed us to determine the risk of food contamination from the air, e.g. in shops and kitchens, by the analysis of the air. Estimations showed that concentrations in the air of shops should not exceed 1 mg/m³ if tetrachloroethylene concentrations in foods are limited to 100 g/kg (slightly higher concentrations can be accepted for the other three compounds); in kitchens of restaurants and households, even 0.3 mg/m³ cause the target concentration to be exceeded rather frequently. If the limit in foods is 50 g/kg, recommended maximum concentrations in air are 0.5 and 0.15 mg/m³. The data also shows that the recommended limits for concentrations in air conflict with the accepted emission limits: If emission at the accepted limit occurs near shops or households, contamination of foods far exceeds that considered as tolerable.

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Übergang von Tri- und Tetrachlorethylen, Benzol und Toluol aus der Luft in Lebensmittel

Zusammenfassung Für Tri- und Tetrachlorethylen, Benzol und Toluol wurden Übergangsgeschwindigkeiten aus der Luft in Lebensmittel sowie Gleichgewichtskonzentrationen in Luft und kritischen Lebensmitteln bestimmt. Aus diesen Daten ließen sich maximale Konzentrationen in der Luft abschätzen, welche die Verunreinigung kritischer Lebensmittel in akzeptablen Grenzen halten. Das erlaubt uns, das Risiko von Lebensmittelverunreinigung aus der Luft, z. B. in Läden und Küchen, durch Luftanalyse zu bestimmen, wofür eine einfache Methode benutzt wird. Unter der Annahme einer maximalen Tetrachlorethylen-Konzentration in Lebensmitteln von 100 g/kg (z. B. deutsche Höchstmengenverordnung) wird abgeschätzt, daß Konzentrationen in Läden 1 mg/m³ nicht überschreiten dürfen (die Gehalte der anderen drei Substanzen dürfen leicht höher sein). In Küchen von Gaststätten oder Haushalten wird die Zielkonzentration in Lebensmitteln bereits bei 0,3 mg/m³ ziemlich häufig überschritten. Für die Schweiz (50 g/kg für Lebensmittel) werden 0,5 und 0,15 mg/m³ vorgeschlagen. Die Resultate zeigen aber auch, daß die empfohlenen Maximalkonzentrationen in der Luft leicht mit den Emissionsgrenzwerten in Konflikt geraten: Bei legalen Emissionen in der Nähe von Läden oder Haushalten kann die Lebensmittelkontamination die Grenzwerte bei weitem übersteigen.

     

Is recycled newspaper suitable for food contact materials? Technical grade mineral oils from printing inks

Recycled paper and board used in food packaging materials (boxes, paper bags) often cause migration of mineral oil into food at levels which are unacceptable according to present toxicological assessments. When foods in recycled board are densely packed into larger boxes or onto pallets, most of the hydrocarbons up to n-C₂₀ may migrate into the packed food within a few weeks, those up to n-C₂₈ at a decreasing rate. Unprinted recycled board contained 300–1,000 mg/kg mineral oil <n-C₂₈. The main sources are the inks used for printing newspapers: newspapers contained roughly 3,000 mg/kg mineral oil <n-C₂₈. These mineral oils fall into classes for which JECFA established a tolerable daily intake of 0.01 mg/kg body weight. Using standard assumptions for calculating specific migration limits, a maximum tolerable concentration in food of 0.6 mg/kg is derived. This evaluation assumes highly refined white oils, whereas the oils found in recycled board are of technical quality and contain 15–25% aromatic compounds, predominantly with 1–3 aromatic rings, as shown by comprehensive GC × GC. This finding precipitates authorities into a dilemma: recycling is supported for the sustainable use of materials, but on the basis of present toxicological assessments the migration is often far beyond acceptable.     

Conductivity for soot sensing: possibilities and limitations

In this study we summarize the possibilities and limitations of a conductometric measurement principle for soot sensing. The electrical conductivity of different carbon blacks (FW 200, lamp black 101, Printex 30, Printex U, Printex XE2, special black 4, and special black 6), spark discharge soot (GfG), and graphite powder was measured by a van der Pauw arrangement. Additionally the influence of inorganic admixtures on the conductivity of carbonaceous materials was proven to follow the percolation theory. Structural and oxidation characteristics obtained with Raman microspectroscopy and temperature programmed oxidation, respectively, were correlated with the electrical conductivity data. Moreover, a thermophoretic precipitator has been applied to deposit soot particles from the exhaust stream between interdigital electrodes. This combines a controlled and size independent particle collection method with the conductivity measurement principle. A test vehicle was equipped with the AVL Micro Soot Sensor (photoacoustic soot sensor) to prove the conductometric sensor principle with an independent and reliable technique. Our results demonstrate promising potential of the conductometric sensor for on-board particle diagnostic. Furthermore this sensor can be applied as a simple, rapid, and cheap analytical tool for characterization of soot structure.     

CDMA/HDR: a bandwidth efficient high speed wireless data servicefor nomadic users

This article presents an approach to providing very high-data-rate downstream Internet access by nomadic users within the current CDMA physical layer architecture. A means for considerably increasing the throughput by optimizing packet data protocols and by other network and coding techniques are presented and supported by simulations and laboratory measurements. The network architecture, based on Internet protocols adapted to the mobile environment, is described, followed by a discussion of economic considerations in comparison to cable and DSL services     

Mineral oil polyaromatic hydrocarbons in foods, e.g. from jute bags, by on-line LC-solvent evaporation (SE)-LC-GC-FID

 On-line and automated LC-SE-LC-GC-FID was used for the analysis of polyaromatic hydrocarbons in foods contaminated with mineral oil products. The detection limit for a fraction was around 1 mg/kg. Batching oil from jute bags introduces two-ring and three-ring aromatic compounds into foods (shown for rice), and environmental contamination of fish introduces primarily two-ring compounds. For other foods containing mineral oil material from unknown sources, the analysis provided important information about the type of oil involved (shown for a sample of linseed oil, a safflower oil and a chocolate). Received: 26 February 1996 / Revised version: 3 June 1996     

Human bone cells stimulate the growth of human breast carcinoma cells

Human breast cancer cells were cultured together with their metastatic target, bone tissue, to analyze possible growth promotion effects. The coculture of human osteosarcoma cells (TE-85) with human mammary carcinoma cells (ZR-75.1) resulted in up to 8.4-fold stimulation of proliferation of the breast tumor cells. Cell contact of the two cultures was permitted through the channels of Nuclepore filters. However, physical contact turned out not to be necessary, since the proliferative stimulus was also mediated by a bone-derived diffusible factor. Conditioned medium (CM), collected from human primary bone cultures, enhanced the rate of proliferation of several breast tissue cell lines (ZR-75.1, BT-20, HBL-100), while some lines were not affected by osteoblast CM. Breast tissue lines responding to bone CM express low to intermediate levels of the c-erbB-2 gene, in contrast to nonstimulated lines, which overexpress the gene. Recent observations of metastatic spread in breast cancer patients suggest a distinctive pattern of secondary tumor distribution in association with c-erbB-2 protein expression. Bone tissue seems to be a preferential target for metastases of c-erbB-2-negative breast tumors.     

Cutaneous diphtheria in returning vacationers--mirror of inappropriate vaccination practice?

The causative agent for diphtheria is Corynebacterium diphtheriae, which is transmitted from person to person from the throat of carriers or from patients with active cutaneous diphtheria. The disease occurs in preexisting ulcers, but it may also appear on apparently normal skin. Although primary cutaneous diphtheria starts as a vesicle or pustule, most patients feature a reddish ulcer with undermined borders. The lesion is tender but hypesthesia develops after 2 weeks. The clinical diagnosis is based on the history of travelling in endemic regions and bacteriological studies. The current increase of diphtheria in the Western world is partly caused by rising tourism and a decline of booster vaccination in adults. After trauma with ulcerations of the skin we suggest to perform a booster vaccination not only for tetanus but also for diphtheria. In addition, persons travelling to endemic regions should receive a booster vaccination for tetanus and diphtheria, which is available as a combined preparation.     

Indirect immobilization of recombinant proteins to a solid phase using the albumin binding domain of streptococcal protein G and immobilized albumin

Gradient elution reversed-phase high-performance liquid chromatographic and capillary electrophoretic separations were optimised to separate substance P (SP) and twelve of its fragments. The methods were applied to a study of the in vivo metabolism of substance P in the rat after intrastriatal injection of the peptide (10 nmol). SP and significant amounts of its N-terminal fragments, SP(1-7) and SP(1-4), were detected but no major C-terminal fragments could be identified. At the concentration studied, the metabolism of SP was shown to follow zero order elimination kinetics with a rate of decay of 0.2 nmol/min. As we have shown that SP(1-4) and SP(1-7) can be produced in vivo in the striatum in relatively large amounts, it is conceivable that these fragments contribute to the overall pharmacological pattern of activity of the parent peptide.     

Performance enhancement of diindenoperylene-based organic photovoltaic cells by nanocolumn-arrays

Crystalline and uniform nanocolumns of the organic semiconductor diindenoperylene (DIP) were fabricated by glancing-angle deposition and employed in organic photovoltaic cells (OPVCs) forming an interdigitated donor/acceptor heterojunction, with fullerene as electron acceptor. In comparison to reference bilayer devices the nanocolumn-based solar cells exhibit increased power conversion efficiency. Based on a comprehensive structural and morphological analysis, we identify three advantages of the interdigitated nanocolumn structures: (i) The active donor/acceptor interface area, crucial for exciton dissociation, is increased and the column diameter is in the range of the exciton diffusion length. (ii) The molecular orientation of DIP is such in the nanocolumns that light absorption is enhanced. (iii) The ubiquitous presence of vertical interfaces throughout nanocolumn-based devices is further beneficial to light absorption, as it fully compensates wavelength-dependent interference effects within the device structure. This work shows how the benefits of nanocolumns can go beyond simple interface area enlargement to improve the efficiency of OPVCs.