AhR transcriptional activity in serum of Inuits across Greenlandic districts

<p>Abstract</p> <p>Background</p> <p>Human exposure to lipophilic persistent organic pollutants (POPs) including polychlorinated dibenzo-<it>p</it>-dioxins/furans (PCDDs/PCDFs), polychlorinated biphenyls (PCBs) and organochlorine pesticide is ubiquitous. The individual is exposed to a complex mixture of POPs being life-long beginning during critical developmental windows. Exposure to POPs elicits a number of species- and tissue-specific toxic responses, many of which involve the aryl hydrocarbon receptor (AhR). The aim of this study was to compare the actual level of integrated AhR transcriptional activity in the lipophilic serum fraction containing the actual POP mixture among Inuits from different districts in Greenland, and to evaluate whether the AhR transactivity is correlated to the bio-accumulated POPs and/or lifestyle factors.</p> <p>Methods</p> <p>The study included 357 serum samples from the Greenlandic districts: Nuuk and Sisimiut (South West Coast), Qaanaaq (North Coast) and Tasiilaq (East Coast). The bio-accumulated serum POPs were extracted by ethanol: hexane and clean-up on Florisil columns. Effects of the serum extract on the AhR transactivity was determined using the Hepa 1.12cR mouse hepatoma cell line carrying an AhR-luciferase reporter gene, and the data was evaluated for possible association to the serum levels of 14 PCB congeners, 10 organochlorine pesticide residues and/or lifestyle factors.</p> <p>Results</p> <p>In total 85% of the Inuit samples elicited agonistic AhR transactivity in a district dependent pattern. The median level of the AhR-TCDD equivalent (AhR-TEQ) of the separate genders was similar in the different districts. For the combined data the order of the median AhR-TEQ was Tasiilaq > Nuuk ≥ Sisimiut > Qaanaaq possibly being related to the different composition of POPs. In overall, the AhR transactivity was inversely correlated to the levels of sum POPs, age and/or intake of marine food.</p> <p>Conclusion</p> <p>i) We observed that the proportion of dioxin like (DL) compounds in the POP mixture was the dominating factor affecting the level of serum AhR transcriptional activity even at very high level of non DL-PCBs; ii) The inverse association between the integrated serum AhR transactivity and sum of POPs might be explained by the higher level of compounds antagonizing the AhR function probably due to selective POP bioaccumulation in the food chain.</p

Étude du gonflement des sols pour des projets de tunnels

Cette communication porte sur l’étude du gonflement d’une marne « intacte » réalisée à l’aide d’un œdomètre flexible. Le dispositif utilisé autorise une certaine déformation latérale de l’éprouvette lors du gonflement et permet la mesure de la pression de gonflement exercée dans cette direction. La variation de la rigidité de l’œdomètre flexible permet d’étudier l’influence de la déformation du sol sur le gonflement et de reproduire les conditions rencontrées lors de la construction de tunnels flexibles dans des sols gonflants. Les essais réalisés montrent que la rigidité de l’anneau œdométrique ainsi que la stratification de l’éprouvette affectent sensiblement le gonflement

Analysis of PCDD/Fs in human blood plasma using CALUX bioassay and GC-HRMS: a comparison

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Dioxin body burden among blood donors before and after the Belgian dioxin/PCB incident.

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Validation of the CALUX bioassay for PCDD/F analyses in human blood plasma and comparison with GC-HRMS

Following the dioxin crisis of 1999, several studies were conducted to assess the impact of this crisis on the dioxin body burden in the Belgian population. The Scientific Institute of Public Health identified a population from whom plasma samples were available and from whom, during the follow up survey, plasma samples were obtained in 2000. In total, 496 samples were collected for GC-HRMS and CALUX analyses to verify statistical assessment conclusions. This study was seen as an opportunity to validate the CALUX bioassay for biological sample analysis and to compare toxic equivalency (TEQ) values obtained by the reference GC-HRMS technique and by the screening method. This article focuses on the validation results of the CALUX bioassay for the analyses of the dioxin fractions of blood plasma. The sample preparation is based on a liquid-liquid extraction, followed by an acid silica in series with an activated carbon clean-up. A good recovery (82%) and reproducibility (coefficient of variation less than 25%) were found for this method. Based on 341 plasma samples, a significant correlation was established between the bioassay and chemical method (R = 0.64). However, a proportional systematic error was observed when the results obtained with the CALUX bioassay were regressed with the results from the GC-HRMS analyses. The limit of quantification (LOQ) used to calculate TEQ values from the GC-HRMS determinations, the use of the relative potency values instead of the toxic equivalent factor and the potential of CALUX bioassay to measure all compounds with affinity for the AhR may partly explain this proportional systematic error. Nevertheless, the present results suggest that the CALUX bioassay could be a promising valid screening method for human blood plasma analyses. (C) 2004 Elsevier B.V. All rights reserved

Reproduction of European eel jeopardised by high levels of dioxins and dioxin-like PCBs

ioxins, furans and dioxin-like polychlorinated biphenyls (PCBs) were analysed in muscle tissue from yellow phased European eel (Anguilla anguilla) from 38 sites in Belgium. Dioxin concentrations in eel vary considerably between sampling locations, indicating that yellow eel is a good indicator of local pollution levels. Measured levels of dioxin-like PCBs are much higher than those of the dioxins and furans. In the majority of the sites, eel has levels considered to be detrimental for their reproduction. Field levels of dioxin and dioxin-like PCBs are therefore suggested as an additional causal factor contributing to the decline of the European eel. 42% of the sampling sites show especially dioxin-like PCB levels exceeding the European consumption level (with a factor 3 on average). Human consumption of eel, especially in these highly contaminated sites, seems unjustified

Validation and interpretation of CALUX as a tool for the estimation of dioxin-like activity in marine biological matrixes.

Among the different analytical tools proposed as an alternative to the very expensive gas chromatography high-resolution mass spectrometry (GC-HRMS) analyses of polychlorodibenzo-p-dioxin and polychlorodibenzofurans, Chemically Activated LUciferase gene eXpression (CALUX) in vitro cell bioassay is very promising. It allows the analyses of a high number of samples since it is relatively fast, inexpensive, and sensitive. However, this technique is not yet widely applied for screening or environmental monitoring. The main reasons are probably the lack of validation and the difficulty in interpreting the global biological response of the bioassay. In this paper, the strict quality control criteria set up for the validation of CALUX are described. The validation has shown good repeatability (relative standard deviation (RSD) = 9%) and good within-lab reproducibility (RSD = 15%) of the results. The quantification limit, in the conditions applied in this paper, is 1.25 pg CALUX-TEQ/g fat. Comparison of CALUX and GC-HRMS analysis was made for various marine matrixes (fishes, mussels, starfishes, sea birds, and marine mammals). Good correlations are usually observed, but there are systematic differences between the results. Attempts are made to identify the origin of the discrepancy between the two methods