Évaluation du risque toxique lié à la prévalence de trihalométhanes dans l'eau utilisée pour la dialyse

L'hémodialyse est une thérapeutique réservée aux sujets insuffisants rénaux en attente d'une greffe. Elle permet de recueillir dans un soluté aqueux les déchets que l'organisme ne peut plus évacuer par voie rénale. L'eau nécessaire à la préparation de ce dialysat représente un volume de 90 à 200 litres par séance et par sujet. Elle est obtenue en faisant subir à l'eau du réseau de distribution un traitement complémentaire. Celui-ci comporte en milieu spécialisé une chloration, un adoucissement par résines cationiques, une filtration sur colonne de charbon actif en grains et une osmose inverse.Les trihalométhanes sont probablement les sous-produits de chloration les plus répandus dans les eaux distribuées. Certains parmi eux sont cancérigènes chez l'animal et mutagènes in vitro. Chez l'homme, leurs effets à faibles doses et à long terme restent discutés. Compte tenu des importants volumes d'eau nécessaires à la pratique de l'hémodialyse, il nous a paru intéressant d'observer l'efflcacité du circuit de pré-traitement sur ces composés et d'évaluer les doses auxquelles sont exposés les patients qui bénéficient de cette thérapeutique.Des prélèvements ont été réalisés aux différentes étapes du pré-traitement, de façon hebdomadaire dans deux installations identiques, à la recherche de trihalométhanes. Ils permettent de constater que du chloroforme à une concentration moyenne de 10,5 llgA est encore présent en bout de chaîne. En tenant compte des volumes d'eau utilisés pour chaque séance, ceci signifie que les patients dialysés sont exposés, selon leur âge, à des doses pouvant atteindre jusqu'à dix fois la valeur préconisée dans l'eau potable par l'OMS. La moitié de ce chloroforme est susceptible de passer dans la circulation sanguine et d'exercer un effet toxique. Cette situation peut être corrigée par le choix d'une ressource en eau à charge organique faible, par un renouvellement fréquent du charbon actif et par l'utilisation de membranes en polyamides dans les modules d'osmose inverse. Ces résultats doivent amener à une réflexion plus générale sur la présenoe de sous-produits de la chloration et de micropolluants dans l'eau utilisée en dialyse. Ils doivent également inciter les cliniciens à rechercher, chez les dialysés les plus exposés, d'éventuels effets délétères liés à ces produits.Hemodialysis is an indispensable therapy for patients with chronic renal failure. Two or three times a week and over several years, their blood is dialyzed in an artificial kidney against a dialysis fluid called dialysate.Each time, 90 to 200 liters of this fluid will flow through the apparatus. Before being mixed with the dialysis concentrate, the water will be treated in order to eliminate harmful substances such as aluminum or endotoxins.Trihalomethanes (THM) are probably the most widespread chlorination byproducts of tap water. Most of them are known as carcinogens for animals and mutagens in vitro. Although their hepatotoxicity and nephrotoxicity are obvious after acute intoxication, their effects at low doses on human health have still not been clearly demonstrated.Considering the great amount of water required by hemodialysis patients, we found interested in determining wether the control of these substances by the hospital water treatment plant was efficient. We decided then to analyze weekly and during two months, the tap water of two hemodialysis departments for THM, before and after various forms of treatment. The treatment in both departments was the same and made up of four important stages: chlorination, softening, charcoal filtering and reverse osmosis.THM determinations were conducted using the headspace technique with a gas chromatograph equipped with a split injector and an [sup]63Ni electron capture detector.Our results show that chloroform and dichlorobromomethane were present in tap water. Their respective mean concentration in both department came to 56 µg/l and 5 µg/l. After chlorination and water softening, these figures had moderately but significantly increased. In the first department, thanks to new granular activated carbon, a large part of THM (especially dichlorobromomethane) had been removed. However after seven weeks, this treatment was no longer efficient and only 7% of the influent chloroform and 50% of the dichlorobromomethane could be removed. In the second department, the charcoal filter had already been working for more than one year at the beginning of our study. No decrease of the chloroform concentration had been observed and dichlorobromomethane had significantly increased. 80 to 90% of influent THM were removed after the double stage of reverse osmosis using polyamide membranes. With new granular activated carbon, the dialysis fluid only contains 1 µg/l of chloroform. But after seven weeks or more, it will reach an average of 10.5 g/l of chloroform and 1 µg/l of dichlorobromomethane. These figures are probably underestimated as our study was performed in winter and THM concentrations are less important during that season.These results mean that during a single session, 0.9 to 2.1 mg of chloroform will reach the artificial kidney. Depending on the weight of the patients, this exposure will be equivalent up to 10 times the value recommended by the World Health Organization (WHO) for drinking water.The last part of our study monitored the chloroform concentration in dialysate coming out the artificial kidney during an hemodialysis period. A significant decrease, reaching up to 45% of the influent amount, was observed. This result suggests that some of the chloroform must have crossed the dialysis membrane.According to all these results, we think that it would be of great interest to explore the metabolism of chloroform on hemodialysis patients and to search for eventual toxic effects. Practical advices to people in charge of water treatment plants in hemodialysis department would be to use raw water with low concentrations of humic materials, in order to restrict THM formation. The charcoal filter should be changed more often (probably after 6 or 7 weeks). Alternatively, ways could be found for rapid regeneration of charcoal for THM removal. Finally and according to previous studies, a polyamide membrane should be systematically used for reverse osmosis.Our study could eventually be completed by searching in the dialysis fluid any other chlorination by-products which are responsible to a large extent for tap water mutagenicity

Plasma membrane redox system in the erythrocytes of rowers: Pilot study

The oxidative stress results from a change in the physiological balance between oxidant and antioxidant species. This type of stress is a chemical change in the redox state of cells. The increased production of reactive species is related to an excessive metabolic activation, for example, from an intense physical exercise or an excessive caloric intake (1). In physiological conditions, muscle fibers are provided with an antioxidant system able to keep under control the excessive production of Reactive Oxygen Species (ROS)

Vitamin D in cancer chemoprevention

Context: There is increasing evidence that Vitamin D (Vit D) and its metabolites, besides their well-known calcium-related functions, may also exert antiproliferative, pro-differentiating, and immune modulatory effects on tumor cells in vitro and may also delay tumor growth in vivo. Objective: The aim of this review is to provide fresh insight into the most recent advances on the role of Vit D and its analogues as chemopreventive drugs in cancer therapy. Methods: A systematic review of experimental and clinical studies on Vit D and cancer was undertaken by using the major electronic health database including ISI Web of Science, Medline, PubMed, Scopus and Google Scholar. Results and conclusion: Experimental and clinical observations suggest that Vit D and its analogues may be effective in preventing the malignant transformation and/or the progression of various types of human tumors including breast cancer, prostate cancer, colorectal cancer, and some hematological malignances. These findings suggest the possibility of the clinical use of these molecules as novel potential chemopreventive and anticancer agent

Development of an Integrated Set of Indicators to Measure the Quality of the Whole Traveller Experience

AbstractThe EU project METPEX is developing a measurement tool for the perceived quality of the whole journey experience. Special emphasis is given on the contribution to the overall quality perception from different phases of such experience, from pre-trip information acquisition to the eventual joint use of different services, especially for multimodal trips. Differences among travel means and user groups are investigated as well. Rather than exclusively focusing on public transport, the project also investigates quality issues dealing with other modes, especially walk and bike. Within such framework, the paper presents some sets of indicators distilled through Principal Component Analysis that could be used in different assessment exercises, shortly discusses how such indicators are showing us the different facets of the “quality of transport” concept and identifies future research directions for the project

Red and golden tomato administration improves fat diet-induced hepatic steatosis in rats by modulating HNF4α, Lepr, and GK expression

Introduction: Nonalcoholic fatty liver disease (NAFLD), characterized by lipid accumulation within hepatocytes exceeding 5% of liver weight, is strongly related to metabolic disorders, obesity, and diabetes and represents a health emergency worldwide. There is no standard therapy available for NAFLD. Lifestyle intervention, including phytonutrient intake, is key in preventing NAFLD development and progression. Methods: We used a rat model of NAFLD to evaluate the effect of dietary supplementation with red tomato (RT) and golden tomato (GT)—a patented mix of fruit with varying degrees of ripeness and particularly rich in naringenin and chlorogenic acid—after steatosis development. We assessed the effects on body weight, metabolic profile, and hepatic steatosis. Results and discussion: We found a correlation between the amelioration of all the parameters and the liver gene expression. Our results showed that, together with the reversion of steatosis, the consumption of RT and GT can cause a significant reduction in triglycerides, low-density lipoprotein-cholesterol, fasting glucose, and homeostasis model assessment index. Meanwhile, we observed an increase in high-density lipoprotein-cholesterol according to the amelioration of the general lipidic profile. Regarding hepatic gene expression, we found the upregulation of Gk and Hnf4α involved in metabolic homeostasis, Lepr involved in adipokine signaling, and Il6 and Tnf involved in inflammatory response. Taken together, our results suggest that dietary intake of red and golden tomatoes, as a nutraceutical approach, has potential in preventing and therapeutics of NAFLD

Lineage tracing in the adult mouse corneal epithelium supports the limbal epithelial stem cell hypothesis with intermittent periods of stem cell quiescence

We thank Drs Kevin Painter (Heriot-Watt University), Steven Morley and Richard Mort for their helpful discussion. We also thank Mr Ronnie Grant for his help with the figures, staff at BRR, University of Edinburgh, for their specialised technical services and Drs Bettina Wilm (Liverpool University), Peter Hohenstein, Richard Mort and Alison Mackinnon for kindly providing founder mice. This work was supported by the UK Biotechnology and Biological Sciences Research Council (grants BB/J015172/1 and BB/J015237/1).Peer reviewedPublisher PD

Meta-analysis of non-tumour doses for radiation-induced cancer on the basis of dose-rate

Purpose: Quantitative analysis of cancer risk of ionising radiation as a function of dose-rate