Search

Pollutants of pharmaceutical origin present in water are poorly removed by conventional treatments. In this context, membrane processes are efficient and clean alternative techniques for water depollution. The objective of this thesis was to evaluate the performance of different membrane techniques: nanofiltration (NF), reverse osmosis (RO) and forward osmosis (FO) for the removal of pharmaceutical pollutants (Naproxen, Diclofenac). The three membranes used are made of polyamide of different natures: aromatic for RO and FO membranes and semi-aromatic in the case of the NF membrane. Moreover, for the FO membrane, the active layer of the membrane also contained aquaporins. The evaluation of the new membranes performance showed a much lower rejection rate of naproxen for the NF membrane than for the RO and FO membranes. In addition, during their use, polyamide membranes can be accidentally exposed to sodium hypochlorite used during the cleaning/disinfection steps of the installations. The impact of this exposure on the properties of the membrane materials and their removal performance was evaluated in the case of FO and RO membranes. The membranes were exposed to sodium hypochlorite (NaOCl) solutions at different concentrations, different pH and for different contact times. Surface characterization of the membranes (zeta potential, ATR-FTIR, contact angles) showed a modification of their properties after exposure to NaOCl solutions. Thus, it was highlighted that the contact with NaOCl can lead not only to the modification of the chemical nature of the membrane material but also to the modification of the intermolecular hydrogen bonds network within the polyamide, thus impacting the structure of the membrane material and the retention performances. Nevertheless, depending on the type of membrane (and polyamide), different types of variations have been observed. Finally, it was shown by XPS that, in the case of biomimetic FO membranes, the presence of polymersomes incorporating aquaporins within the polyamide was not impacted by the contact with NaOCl. Thus, the FO membrane retains a good rejection capacity for the molecules studied despite an increase in reverse salt flux.; Les polluants d’origines pharmaceutiques présents dans les eaux présentent une élimination limitée par les traitements conventionnels. Dans ce contexte, les procédés membranaires sont des techniques alternatives de dépollution des eaux efficaces et propres. L’objectif de cette thèse était d’évaluer les performances différentes techniques membranaires : la nanofiltration (NF), l’osmose inverse (RO) et l’osmose directe (FO) pour l’élimination de polluants pharmaceutiques (Naproxène, Diclofénac). Les trois membranes utilisées sont constituées de polyamides de différentes natures : aromatique dans le cas de la RO et la FO et semi-aromatique dans le cas de la NF. De plus, dans le cas de la membrane de FO, la couche active des membranes contenait également des aquaporines. La caractérisation des performances des membranes neuves ont mis en évidence un taux de rejet du naproxène par la membrane de NF bien inférieur à celles des membranes de RO et FO. De plus, lors de leur utilisation, les membranes en polyamide peuvent être exposées accidentellement à l’hypochlorite de sodium utilisé lors de phases de nettoyage/désinfection des installations. L’impact de cette exposition sur les propriétés des matériaux membranaires et leurs performances d’élimination a été évalué dans le cas des membranes de FO et de RO. Les membranes ont été exposées à des solutions d’hypochlorite de sodium (NaOCl) à différentes concentrations, différents pH et pour différents temps de contact. Les caractérisations de surface des membranes (potentiel zêta, ATR-FTIR, angles de contact) ont alors montré une modification de leurs propriétés après exposition aux solutions d’NaOCl. Ainsi, il a été mis en évidence que le contact avec NaOCl peut conduire non seulement à la modification de la nature chimique du matériau membranaire mais également à la modification du réseau de liaisons Hydrogène intermoléculaires au sein du polyamide impactant alors la structure du matériau membranaire et les performances de rétention. Néanmoins, selon le type de membranes (et de polyamide), différents types de variations ont été observées. Enfin, il a été montré par XPS que, dans le cas des membranes biomimétiques de FO, la présence des polymersomes incorporant les aquaporines au sein du polyamide n’était pas impactée par le contact avec NaOCl. Ainsi, la membrane de FO conserve une bonne capacité de rejet des molécules étudiées malgré une augmentation du flux de sel inverse.

The degradation of water resources by the presence of organic matter (OM) and micropollutants requires the implementation of robust drinking water production processes. In this context, many French municipalities such as Saint Cloud and Angers have decided to set up a powdered activated carbon adsorption process coupled to ultrafiltration (PAC/UF). PAC is used upstream of membranes to remove traces of micropollutants while UF membranes provide excellent and constant water quality over time. However, the feedback reveals a degradation of the separation performances related in particular to an aging of the membrane materials and a vulnerability of the process towards some emerging micropollutants such as polar organic compounds (PMOCs).The work carried out during this thesis aims to better understand the consequences of the chemical aging of the membranes used in these processes and to evaluate the micropollutants removal efficiency in order to propose optimization ways. More particularly it has been shown that the main cause of aging is the chlorine exposure of the membranes during washing phases modifying the properties of the materials. In fact, the numerous characterization tools used have made it possible to demonstrate a correlation between the degradation of the hydrophilic agent of the membranes and the increase in the permeability during exposure to chlorine. The study of the membrane performances revealed an alteration of the resistance to fouling towards OM for membranes exposed to chlorine. However, the results obtained to evaluate the selectivity performance of the membranes with respect to viruses have not underlined any major alterations. Adsorption tests have demonstrated the limited efficiency of PAC for PMOCs removal. Indeed, among the molecules tested, the most hydrophobic and aromatic molecules are effectively adsorbed on PAC while the more polar ones are slightly adsorbed. Finally, the use of nanofiltration or low-pressure reverse osmosis, with average rejection rates over 90%, makes them the technological solutions of choice for the removal of PMOCs.; La dégradation des ressources en eaux par la présence de matières organiques (MO) et de micropolluants nécessite la mise en œuvre de procédés de production d’eau potable robustes. Dans ce contexte, de nombreuses municipalités françaises comme Saint Cloud et Angers ont décidé d’implanter un procédé d’adsorption sur charbon actif en poudre couplé à l’ultrafiltration (CAP/UF). Le CAP est utilisé en amont des membranes afin d’éliminer les traces de micropolluants tandis que les membranes d’UF assurent une qualité d’eau produite excellente et constante au cours du temps. Cependant, les retours d’expérience montrent une dégradation des performances de séparation liée notamment à un vieillissement des matériaux membranaires ainsi qu’une vulnérabilité du procédé vis-à-vis de certains micropolluants émergents tels que les composés organiques polaires (PMOCs). Les travaux réalisés au cours de cette thèse visent à mieux comprendre les conséquences du vieillissement chimique des membranes utilisées dans ces procédés et d’évaluer l’efficacité d’élimination de micropolluants afin de proposer des voies d’optimisation. Plus particulièrement il a été montré que la cause principale de vieillissement est l’exposition au chlore des membranes durant les phases de lavage modifiant les propriétés des matériaux. En effet, les nombreux outils de caractérisation utilisés ont permis de mettre en évidence une corrélation entre la dégradation de l’agent hydrophile des membranes et l'augmentation de la perméabilité lors de l'exposition au chlore. L’étude des performances membranaires a mis en évidence une altération de la résistance au colmatage vis-à-vis de la MO pour les membranes exposées au chlore. Cependant les résultats obtenus pour évaluer les performances de sélectivité des membranes vis-à-vis de virus n’ont pas souligné d’altérations majeures. Les essais d’adsorption ont démontré l’efficacité limitée du CAP pour la rétention des PMOCs. En effet, parmi les molécules testées, les molécules aromatiques les plus hydrophobes sont efficacement adsorbées par le CAP tandis que les plus polaires sont peu éliminées. Finalement, l’utilisation de la nanofiltration ou l’osmose basse pression, présentant des taux de rétention en moyenne supérieurs à 90%, en font des solutions techniques de choix pour l’élimination des PMOCs.

Several decontamination technologies exist, however bacterial spores and biofilms remain a concern in a lot of fields, like hospital, alimentary and military. A new foam containing a biocide (sodium hypochlorite or hydrogen peroxide) and a stabilizing agent (Xanthan) has been studied to answer this problematic. This foam can be used in different ways on the field following contaminations: grounds’ spraying, walls’ covering and spraying, full pieces’ filling (walls and ground). The goal of this thesis is to evaluate the biocide efficiency of these foams on spores and biofilms. We optimized experimental protocols in order to study mechanisms of foams’ action on spores and biofilms based on theirs future applications (horizontal, vertical and filling) and depending on different environmental factors which may impact foam decontamination efficiencies (materials, temperatures, soil, …). This thesis work enabled to highlight the Xanthan foam containing 5% NaOCl from the one including 12% H2O2 in military sector. This foam allows a rapid decontamination, about 7 logs of spores in 30 minutes, for each of the three ways of use at 20°C. Moreover, the destruction of biofilms containing 107 logs of bacteria/cm² was achieved in 1 hour on a horizontal support by filling. This NaOCl foam is ready to be used for industrials.; Il existe de nombreuses technologies de décontamination, néanmoins les spores et les biofilms bactériens demeurent une préoccupation majeure dans de nombreux domaines, tels que le secteur hospitalier, alimentaire et de la biodéfense car elles sont résistantes. Une mousse novatrice contenant un biocide (l’hypochlorite de sodium ou le peroxyde d’hydrogène) et un agent stabilisant (le Xanthane) a été étudiée pour répondre à ce besoin. Cette mousse a la capacité d’être mise en oeuvre de différentes façons sur le terrain par : pulvérisation au sol ; talochage et pulvérisation sur les murs ; remplissage de pièces entières (murs et sols). Le travail de thèse est d’évaluer les modes d’action biocide de ces mousses sur les spores et les biofilms. Afin d’étudier le mode d’action de ces mousses des protocoles expérimentaux ont été mis au point sur les spores et les biofilms suivant leurs futures mises en oeuvre (horizontale, verticale et remplissage) et suivant différents facteurs environnementaux pouvant influencer leur efficacité de décontamination (températures, salissures, matériaux, …). L’ensemble de ce travail de thèse a permis de distinguer l’intérêt de la mousse au Xanthane contenant NaOCl 5% par rapport à celle H2O2 12% pour répondre aux besoins spécifiques de la décontamination des agents de la menace biologique. Cette mousse permet une décontamination rapide de 7 logs de spores en 30 minutes pour chacune des trois voies de mise en oeuvre à 20°C. De plus, elle permet la destruction de biofilms contenant 107 de bactéries/cm² en 1 heure maximum sur un support horizontal et par remplissage. Cette mousse NaOCl est suffisamment mature pour pouvoir réaliser un futur transfert industriel.

The high frequency of iatrogenic incidents during endodontic treatment is a source of stress for the practitioner. These incidents may occur during the different steps of a root canal treatment. During irrigation, extrusion of sodium hypochlorite beyond the apex is a rare but impressive accident. Sodium hypochlorite, is the most common irrigant used in modern endodontics, but when it comes in contact with the periapical tissue, it can cause complications ranging from mild discomfort to serious tissue damage such as the hematoma and hemato-emphysema. The aims of this article are to discuss through the presentation of two clinical cases: Etiological and predisposing factors; Signs guiding to suspicion of accidental injection of sodium hypochlorite. In this work, we focused on clinical keys that help the practitioner in better understanding this accident in order to prevent it or to manage it well when it occurs.

Endodontic infections are characterized by their microbial polymorphism with the presence of pathogenic agents such as bacteria. The aim of this study was to investigate the presence of yeast in the root canals of teeth with pulp necrotic with or without apical periodontitis and to study the sensibility of these at disinfection at sodium hypochlorite to 2.5 %.Root canal samples, taken with paper points before and after disinfection with sodium hypochlorite dosed at 2.5 % on 50 single rooted teeth in 38 patients, were seeded in petri dishes containing Sabouraud Chloramphenicol (SC) (Conda Laboratories, Madrid). These stains were incubated in an incubator at 37°C for 48hours. The presence of yeast was confirmed by white colonies on the entire circumference of the tip paper. The identification of species was done by macroscopic and microscopic examinations associated with Blastese test.The yeast colonies were isolated from 7 teeth (14 %) out of 50. All positive samples were from teeth with an open necrotic pulp (P0.001). The only species found was Candida albicans. Immediate disinfection with sodium hypochlorite at 2.5 % did not show a complete elimination of yeasts.The results of this study show that the canal of necrotic teeth with or without apical periodontitis may shelter yeasts even after immediate disinfection with sodium hypochlorite 2.5 %.

The cleaning processes, especially the use of chlorine solutions, may cause the untimely degradation of the water filtration membranes. While the market for PVDF membrane-based treatment technologies is rapidly expending, only few works deal with the study of their ageing on a long-term basis. In this context, this project focuses on the study of the ageing of two PVDF filtration membranes. Samples are immersed in a sodium hypochlorite solution and the effect of the chlorine solution pH is investigated. The properties of the membranes are characterized throughout the study by tensile tests, hydrophilicity, hydraulic performances and porosity analysis. The evolution of properties is related to the chemical structure of the membranes at a molecular, a macromolecular and a supramolecular scale. Until now, this approach has never been used in the case of PVDF membranes under chlorine conditions. The size exclusion chromatography analyses revealed the most important modifications. The degradation occurs mainly by chain scissions of the PVDF and crosslinking phenomenon in lesser extent. The main modifications occurred at pH less than 10 proving the joint action of OH•, ClO• and Cl• radicals. The ageing of the PVDF membrane containing additives showed at the same time the PVDF degradation and the elimination of the additives. Whereas the properties of the additive-free PVDF membrane were preserved, the elimination of additives led to a modification of the porosity and an increased fouling. However, even if the PVDF degradation is proved, the using properties of the PVDF membranes remain acceptable taking into consideration extreme conditions of ageing studied., Les processus de lavage, et plus particulièrement l'utilisation de solutions chlorées, peuvent engendrer une dégradation prématurée des membranes de filtration d'eau. Alors que le marché des technologies membranaires en PVDF est en pleine expansion, peu de travaux portent sur l'étude de leur dégradation sur le long terme. Dans ce contexte, la thèse a porté sur l'étude du vieillissement de membranes de filtration commercialisées en PVDF. Les échantillons sont immergés dans une solution d'hypochlorite de sodium et l'effet du pH sur leur dégradation est approfondi. Les propriétés mécaniques, d'hydrophilie, les performances hydrauliques ainsi que la porosité sont étudiées. L'évolution des propriétés est mise en relation avec la structure chimique étudiée à différentes échelles : moléculaire, macromoléculaire et supramoléculaire. Cette approche n'a à ce jour jamais été utilisée dans le cas des membranes fibres creuses en PVDF. Les analyses en chromatographie d'exclusion stérique révèlent les modifications les plus importantes. La dégradation du PVDF des membranes se traduit par un phénomène prédominant de coupures de la chaîne principale du PVDF accompagné, dans une moindre mesure, d'un phénomène de réticulation. Les principales modifications sont constatées à des pHs inférieurs à 10 révélant la possible action conjointe des radicaux OH•, ClO• et Cl•. Le vieillissement d'une membrane PVDF additivée montre à la fois une dégradation du PVDF et une élimination des additifs. Alors que la membrane sans additif conserve une stabilité de ses propriétés, l'élimination des additifs entraine une évolution de la porosité et une propension au colmatage plus importante. Cependant, les membranes PVDF conservent des propriétés d'utilisation acceptables au regard des conditions extrêmes de vieillissement étudiées.

This work was devoted to the study of the impact that chemical cleaning with sodium hypochlorite (NaOCl) has on polyethersulfone (PES)/polyvinylpyrrolidone (PVP) (95%/5%) membranes, commonly used for water and milk filtration processes. In onsite plants, chemical cleanings are widely used to maintain membranes filtration properties. The aim of this thesis is to determine the degradation mechanisms of these two polymers in contact with NaOCl and to correlate this information with the evolution of the macroscopic properties of the membrane through a multi scale analysis. Firstly, the study of NaOCl impact on both PVP and PES, treated separately as “model polymers”, showed us that dissolved PVP is oxidised, whereas PES film remains stable. Thanks to the identification of PVP oxidation products, a radical degradation mechanism by means of hydroxyl radicals from NaOCl solution has been proposed. Secondly, in order to overcome membrane heterogeneities, several films with different PES/PVP ratios were prepared by varying the amount of PVP. The immersion of these films in NaOCl solutions provoked the oxidation of both PVP and PES, allowing us to clearly identify the degrading effect that PVP has in PES oxidation. Thirdly, the evolution of PVP chemical structure was correlated with the loss of the membrane mechanical properties, demonstrating that PVP, used as an additive (5%), is the weak point of PES/PVP membranes. The monitoring of PVP oxidation in membranes in contact with NaOCl was proposed as a molecular marker of ageing., Ce travail est consacré à l’étude de l’impact des lavages chimiques à l’hypochlorite de sodium (NaOCl) effectués sur des membranes polymères polyéthersulfone (PES)/polyvinylpyrolidonne (PVP) (95%/5%) utilisées pour la filtration de l’eau ou du lait. Sur les sites d’exploitation les lavages chimiques sont nécessaires pour maintenir les propriétés de filtration des membranes qui se colmatent au cours de leur utilisation. L’objectif de cette étude est de déterminer les mécanismes de dégradation de ces deux polymères au contact de l’agent nettoyant, puis de corréler ces évolutions aux changements de propriétés macroscopiques des membranes en réalisant une analyse multi-échelle. Dans un premier temps, l’étude de l’impact de NaOCl sur des polymères modèles, le PES d’une part et la PVP d’autre part, a montré que la PVP s’oxyde lorsqu’elle est dissoute dans NaOCl ce qui n’est pas le cas de films de PES. A partir de l’identification des produits d’oxydation, un mécanisme d’oxydation radicalaire de la PVP mettant en jeu les radicaux hydroxyles provenant de la solution de NaOCl a été proposé. Dans un deuxième temps, afin de s’affranchir de l’hétérogénéité des membranes PES/PVP, des films de mélanges modèles PES/PVP à différents pourcentages de PVP ont été préparés. Leur immersion dans une solution de NaOCl provoque non seulement l’oxydation de la PVP mais aussi celle du PES montrant sans ambiguïté l’effet pro-dégradant de la PVP sur le PES. Dans un troisième temps, il a été montré que le vieillissement des membranes PES/PVP peut être explicité à partir des résultats obtenus sur les mélanges modèles, et que l’évolution de la structure chimique de la PVP pouvait être corrélée avec la perte des propriétés mécaniques des membranes permettant de faire le lien entre l’évolution de la structure chimique et la perte des propriétés macroscopiques. Il apparait donc au final que l’additif ajouté au PES pour rendre les membranes hydrophiles est le talon d’Achille de la structure. Le suivi de l’oxydation de la PVP contenue dans les membranes exposées à NaOCl a été proposé pour servir de marqueur moléculaire de vieillissement.

In dentistry, residual infection remains a major cause of failure after endodontic treatment; many of these infections involve Enterococcus faecalis. In the current study, we explored the possibility that blue light activated photosensitizers could be used, in principle, to inactivate this microbe as an adjunct disinfection strategy for endodontic therapy. Three blue light absorbing photosensitizers, eosin-Y, rose bengal, and curcumin, were tested on E. faecalis grown in planktonic suspensions or biofilms. Photosensitizers were incubated for 30 min with bacteria then exposed to blue light (450-500 nm) for 240 s. Sodium hypochlorite (3%) was used as a control. After 48 h, the viability of E. faecalis was estimated by measuring colony-forming units post-exposure vs. untreated controls (CFU/mL). Blue light irradiation alone did not alter E. faecalis viability. For planktonic cultures, blue light activated eosin-Y (5 μM), rose bengal (1 μM), or curcumin (5 μM) significantly (p

Hot water quality control inside buildings is assured by thermal or/and chemical disinfection treatments. These disinfection treatments could have an impact on the material degradation. The influence of the addition of sodium hypochlorite and the increase in temperature on the degradation of copper, galvanized steel, PERT/Al/PERT and cPVC pipes was studied. Accelerated ageing tests were conducted under static and dynamic conditions. To carry out the tests under dynamic conditions a scale 1 pilot was designed and built.The chemistry of sodium hypochlorite solutions at temperatures higher than 50°C is complex. Therefore, the species repartition as a function of pH and the decomposition kinetic of sodium hypochlorite solutions had also been studied. This study revealed that, at a given pH, an increase in temperature from 50°C to 70°C produce a significant decrease in concentration of hypochlorous acid. In addition, the decomposition of sodium hypochlorite in chlorates is accelerated by the presence of copper. The chlorates concentration can become significant at 50°C in presence of copper.The results of the ageing test performed on pipes revealed that the addition of sodium hypochlorite increase the degradation rate of copper, galvanized steel and PERT/Al/PERT. However, the degradation rate of cPVC does not seem to be affected by the addition of sodium hypochlorite. An increase in temperature from 50°C to 70°C slightly accelerated degradation of PERT /Al/PERT and cPVC. Concerning copper, at 70°C corrosion is uniform while at 50°C corrosion is by pitting.The conclusions of this study can be useful for the design and the maintenance of hot water systems., Afin de maitriser la qualité d'eau dans les réseaux d'eau chaude sanitaire, des traitements de désinfection thermiques et chimiques sont utilisés. Ces traitements de désinfection peuvent avoir un impact sur la dégradation des canalisations. L'influence de l'addition d'hypochlorite de sodium et de l'augmentation de la température sur la vitesse et le mode de dégradation des canalisations en cuivre, acier galvanisé, PERT/Al/PERT et PVCc a été étudiée. Pour ceci, des essais de vieillissement accéléré ont été réalisés en conditions statiques et dynamiques. Afin de réaliser les essais en conditions dynamiques, un banc d'essais à échelle 1 a été conçu et construit.La chimie des solutions d'hypochlorite de sodium à des températures élevées (>50°C) est complexe, ceci a motivé la réalisation d'une étude complémentaire sur les espèces présentes en fonction du pH et la cinétique de décomposition des solutions d'hypochlorite de sodium. Cette étude a révélé que l'augmentation de la température de 50°C à 70°C à une valeur de pH donnée produit une diminution significative de la concentration en acide hypochloreux. De plus, la décomposition de l'hypochlorite de sodium en chlorates est accélérée par la présence de cuivre et elle peut devenir significative à partir de 50°C.Les essais de vieillissement réalisés sur les canalisations ont révélé que l'addition d'hypochlorite de sodium est pénalisante par rapport à la vitesse de dégradation du cuivre, acier galvanisé et PERT/Al/PERT. Cependant, la dégradation du PVCc ne semble pas se voir affectée par l'addition d'hypochlorite de sodium. L'élévation de la température de 50°C à 70°C paraît accélérer légèrement la dégradation du PERT/Al/PERT et du PVCc. En revanche, avec une chloration de 25 ppm en hypochlorite de sodium, le mode de corrosion du cuivre est uniforme à 70°C tandis qu'il est localisé à 50°C.Les conclusions de ces résultats peuvent être d'utilité pour la conception et la maintenance des réseaux d'eau chaude sanitaire.

Industrial production of two high added value compounds called pelargonic acid and azelaic acid is made possible by the ozonolysis reaction of oleic acid. However, this method has numerous disadvantages in term of ecological impact. In this dissertation, we present an alternative to the current industrial process in order to lower direct or indirect negative environmental impacts when synthetizing azelaic and pelargonic acids. At first we demonstrate that a two-step oxidative cleavage may be preferable to a one-step cleavage. Then we present in details a novel synthesis method which starts with the dihydroxylation of the fatty acids double bond using a well known method, followed by the oxidative cleavage in presence of sodium hypochlorite. One notes that this original fabrication process developed in our laboratory does not require to use transition metals nor organic solvents. As a complement to this work, we have subsequently studied the sodium hypochlorite to determine its role and operating mode in the vicinal diols cleavage reaction, Au niveau industriel, l'accès aux acides azélaïque et pélargonique, composés à forte valeur ajoutée, est possible grâce à une réaction d'ozonolyse de l'acide oléïque. Cependant, cette méthode présente certains désavantages sur le plan écologique. Le but de cette étude a donc été de développer une méthode alternative à ce procédé industriel, visant à limiter autant que possible les impacts écologiques, directs ou indirects, lors de la synthèse des acides azélaïque et pélargonique. Nous avons ainsi montré qu'un clivage en deux étapes peut être préférable à un clivage oxydant en une étape. Notre procédé propose ainsi, dans un premier temps, une dihydroxylation de la double liaison d'acides gras par une méthode connue, laquelle est suivie par un clivage oxydant en présence d'hypochlorite de sodium. Ce nouveau procédé mis au point au sein du laboratoire présente l'avantage de ne nécessiter l'emploi ni de métaux de transition, ni de solvant organique. Nous avons par la suite étudié l'hypochlorite de sodium afin de déterminer son rôle et son mode d'action dans la réaction de clivage de diols vicinaux

To assess the impact of the sputum samples treatment by sodium hypochloride (NaOCl) 5% on the acid-fast bacilli (AFB) gradations in the tuberculosis diagnosis, 516 sputum samples were collected in 244 patients. The sputum smears made before and after expectorations treatment with NaOCl 5%, were stained by Ziehl-Neelsen hot method. The values obtained from the two microscopic readings were compared by using the chi2 test of McNemar. The statistical significance was set at p0.05. The results obtained before using NaOCl 5% showed that 357 samples were negative, while 41 were AFB scanty (gradation 1-9), 28, 40 and 50 were positive 1+, 2+ and 3+. After treatment, among 357 AFB negative expectorations, 14 (3.9%) were AFB-positive, while the AFB gradation increased for 77 (48.4%) in the 159 positive specimens. The two microscopic readings differ significantly (p = 0.001). The application of the process on a routine basis in the laboratory will require a reorganization of the tasks in order to give back the results to the patients in time. It is necessary to take into account the aspect of the samples.

We report two cases of squamous cell carcinoma (SCC) in two black women (phenotype VI) using bleaching compounds for cosmetic purposes over a period of 15 years.Two women (aged 45 and 47 years) with a long history of cosmetic use of bleaching compounds consulted at a dermatology unit for skin tumours. A diagnosis of SCC was confirmed by histological examination of tumour biopsies. One patient was HIV-positive. Surgical treatment was performed in both cases: simple postoperative complications were seen in one patient but the other died at home following recurrence of carcinoma in the year following diagnosis.To our knowledge, theses two cases represent the first description of SCC occurring after prolonged cosmetic use of bleaching compounds. Carcinoma occurred in both cases in skin exposed to sun. In our patients, the mechanism of carcinogenesis may have involved melanin destruction, solar exposure and corticosteroid-induced immunosuppression. A direct carcinogenic effect of hydroquinone or other unidentified compounds is another possibility; the carcinogenicity of hydroquinone is well established in rodents. While these observations do not provide formal proof of any implication of depigmentation products in SCC, they emphasize the need for monitoring of dark-skinned women using skin lighteners.

The aim of this study was to evaluate the antibacterial effectiveness of 2.5% sodium hypochlorite on endocanal bacteria related to the time contact Within root canal.110 teeth were prepared and inoculated with Enterococcus feacalis. All teeth were irrigated with a same volume and exposed a period ranging 1 to 10 min. Canals were sampled before and after time contact.All time reduced the number of bacterial cells within the root canal (p0.05). There was no significant difference after the time contact of 3 min (p0.05). Lack of effectiveness might be caused by irrigant to reach microorganism in dentinal tubules.

Calcium hydroxide has found its use in endodontic treatments. On the other hand, chlorhexidine is more and more proposedfor uses in clinical endodontics. Could chlorhexidine surpass calcium hydroxide and what are the benefits of chlorhexidine? This literature overview concludes that both medications are useful and that further studies are necessary before chosing one above the other.

In recent years, an important innovation in the field of dentistry has been the introduction of nickel-titanium alloy instruments. Superelasticity and shape memory are the main mechanical properties of this alloy which prompted its use in endodontics. Due to these characteristics, NiTi instruments have been demonstrated to preserve the original anatomy, the shape and position in space of the apical foramen. This literature review of mechanical properties of NiTi endodontic instruments aims to provide clinicians with a better understanding of their advantages and limits.

Location of the apical foramen using an electronic apex locator to determine working length is more accurate than using radiographs alone. The Neosono Co-pilote is not adversely affected by the presence of sodium hypochlorite and gives us acceptable results in dry canals. Hence, it is today possible to realize endodontic treatment without X ray determination.

The aim of this monocentric, randomized, comparative, open study was to evaluate the safety of Amukine 0.06% solution (an isotonic hypochloride sodium solution) versus a 5% povidone iodine solution (Bétadine 5% solution for ocular irrigation) in antisepsis before cataract surgery.One hundred and thirteen patients, aged between 49 and 90 years, were included and split, after randomization, into two groups: one testing Amukine 0.06%, the other testing a 5% povidone iodine solution. For each group, after local anesthesia, the antiseptic procedure consisted of an antisepsis of periocular teguments followed by an eye antisepsis through the instillation of two drops of the tested product in the conjunctival fornices. The safety evaluation was performed by grading superficial punctate keratitis 24 hours after surgery (slit lamp examination after fluorescein instillation). Conjunctival hyperemia scores by examination of the bulbar conjunctiva before the first instillation, immediately before surgery, and 24 hours after surgery were also compared.One hundred and seven reports were analyzed. Concerning the presence of corneal superficial punctate keratitis 24 hours after surgery, mean scores were not different (0.27 for the Amukine 0.06% group and 0.38 for the povidone iodine group; p=0.27 Mann Whitney test). The observations did not show a different progression of conjunctival hyperemia depending on the treatment group (p=0.65 (immediately after application) and p=0.52 (after 24 hours); Mann Whitney test).In this study, the ocular safety of Amukine 0.06% solution was not different from a 5% povidone iodine solution. Therefore, Amukine 0.06% is a new interesting approach to surgical antisepsis in ophthalmology and an alternative in case of iodine allergy.

Since our last review, there have been new developments in several jurisdictions in the area of HIV/AIDS and prisons. This column reviews some important developments in Canada and in the US: the results of the evaluation of HIV/AIDS harm-reduction measures in the Canadian federal prison system; another Canadian inmate's fight for methadone maintenance treatment in prison; an important article on health care in Canadian prisons which states that there is little evidence that the federal prison system "is making any serious effort to provide treatment to any drug users"; the US Supreme Court's refusal to review a lower court's ruling permitting Alabama prisons to segregate HIV-positive inmates; an important ruling stating that inmates are entitled to receive medications in jail without interruption; and research showing that women inmates in the US are 23 times more likely to have AIDS than women in the general population.

A U.S. study of WF10, a mixture of Hydrogen Peroxide and bleach, suggested that WF10 improves the function of macrophages, damages HIV once WF10 is released by an infected cell, enhances resistance to infections, and does not interfere with AZT or ddI activity. WF10 does not show any toxicity in the liver, bone marrow, or kidneys; side effects were mild and temporary. WF10 is available from Canada through Health Canada's Special Access Programme and costs approximately $1,200 to $1,600 per cycle.

Caustic products are responsible for the most serious cases of poisoning, which are always emergency cases. Application of current intervention procedures has decreased both morbidity and mortality. Water-diluted bleach, the ingestion of which remains extremely frequent, is a moderate irritant rather than a caustic product. Emission of gas produced when mixing bleach with other agents can be responsible for choking gas poisoning. Anionic and nonionic detergents are mostly dangerous because of their foam-producing properties. Mercury vapours and methanol are other potentially hazardous products.

A sodium hypochlorite solution (NaClO) containing 0.5% w/v of available chlorine (0.5% Cl2 or 5000 ppm) is a good and cheap solution for disinfecting material used to medical care. It is effective against bacteria, fungi and viruses. It is easy to prepare. It can be a good solution for antisepsis and disinfection in dispensaries in developing countries. However, it is not always easy to keep it in adequate conditions. That's the reason why we have evaluated the durability of such a solution of NaClO exposed to disadvantageous factors, specially daylight and air, and its antibacterial effectiveness. In this study, after exposure of NaClO containing 4350 ppm of available chlorine to these adverse conditions, the final concentration of NaClO was 2300 ppm of available chlorine and was found effective for decontamination of medical material. A protocol for conservation and use of a sodium hypochlorite solution (0.5% Cl2) in dispensaries of developing countries is proposed.

The effectiveness of ultrasonic and sonic instrumentation in eliminating the smear layer from instrumented root channels. The results were examined with S.E.M. and the effective areas of dental diffusion were calculated using the computerized image analyzer. The agents used: citric acid at concentrations of 10, 25 and 50% as well as 15% EDTA, proved their efficiency with both types of mechanical instrumentation. However, the area of diffusion found was always greater using the ultrasonic instrumentation technique as opposed to the sonic instrumentation technique. 1, 2.5 and 5.25% sodium hypochlorite, as well as 10 volume hydrogen peroxide were not effective in eliminating the smear layer using both types of instrumentation.

The authors are discussing the interest of promoting the use of bleach as a powerful disinfectant among drug users. Following the researches conducted in the United States of America, the use of bleach has been introduced on an experimental basis in Paris. This action-research allowed to meet 1500 drug users who have received bleach and prevention materials. The evaluation of the action was conducted on a sample of 478 subjects. It was found that bleach could be used by addicts for syringe decontamination. The communication strategy implies a direct personal contact and a non judgmental message. Syringes must be carefully cleaned and rinsed at least twice with bleach in order to allow a one minute contact. In the absence of a new syringe the use of bleach provides a reasonable means of risk reduction if detoxification cannot be achieved.

During canal preparation, the repeated passage of instruments provokes the formation of smear on the surface of the dentin. It is advisable to eliminate that, so as to increase antisepsis and filling impermeability. This is obtained by means of an irrigation, using a chelate compound of 6% citric acid for 60 seconds, at the end of the preparation.

Accidental bleach ingestion is frequent in children but there is no agreement on its management. The results of a survey among 11 French poison centres about their recommendations in this intoxication are reported. Most of the centres adapt their guidelines according to the quantity and the concentration of the ingested bleach. In case of diluted bleach, no centre recommends an hospitalization when the quantity is smaller than 100 ml, whereas four of the 11 centres recommend it when the quantity is greater than 100 ml. In case of concentrate bleach ingestion nine of the 11 centres recommend an hospitalization whatever the amount, eight of them performing an emergency upper gastro intestinal (GI) endoscopy if clinical signs are present. In case of large ingestion of concentrate bleach ten centres recommend the hospitalization, eight perform an upper GI endoscopy between 6 and 8 hours post ingestion according to clinical signs, and two perform a systematic emergency upper GI endoscopy. Tablets and new bleach are considered as concentrate bleach. From these informations and a review of the literature, the authors emphasize the importance of the clinical signs as criteria for prediction of GI lesions regardless of the quantity or the concentration of ingested bleach.

Sanitary U bends are very contaminated places from a microbiological point of view. They may even be dangerous for immunocompromised patients. Although daily chloride disinfection of U-bends is ineffective, it seems to work when performed after each use of sanitary devices. On line disinfection reduces not only U-bend bacteriological contamination but also all surrounding surfaces.

The present study was not about the interest of the association of ultrasonic instrumentation with irrigation in the root canal therapy, but about the wear of the K files themselves. The results showed with the assistance of the sono-synergistic system, files are almost as clean as the sterile are. This is important for the prevention of possible contamination.

The authors reviewed 125 cases of accidental ingestion of caustic substances admitted to a general pediatrics department over the last four years. L'eau de Javel (bleaching agent with sodium hypochloride) was the most frequently encountered caustic substance (89%). Esophagogastric fibroscopy was performed in 100 cases and esophageal lesions were classified according to tree grades of severity. In 46 cases, fibroscopy was normal, while severe esophagogastric lesions (grades 2 and 3) were found in 26 cases. On follow-up, six patients developed esophageal stricture, three of them after concentrated, eau de Javel ingestion. Stricture was severe in four cases, and required colonoplasty of the esophagus; it was limited in two cases and required endoscopic dilatation only. The authors emphasize the frequency and the severity of lesions caused by chloride bleach (eau de Javel) and recommend that fibroscopy be carried out in all children following ingestion of any caustic substance, even in the absence of oropharyngeal burns.

Sodium hypochlorite is still today the most popular irrigating solution used in endodontics. History, chemical and bactericidal properties, effect on periapical tissue, dissolution of pulp tissue, removal of debris and depth of penetration and attempts to improve its activity are discussed in this article.

Adenocarcinoma of the esophagus is found almost exclusively at the level of the cardia. It is exceptional to find it in the middle part of the esophagus in the absence of involvement of the cardia. In the long term, caustic burns of the esophagus may favour malignant degeneration. The latter is always squamous cell carcinoma. In our patient, a 28 year old man, a cylindrical carcinoma of the thoracic esophagus was detected four years after the ingestion of concentrated sodium hypochlorite. The caustic burn followed by carcinoma were of special significance in this case owing to the development of an adenocarcinoma.

Sodium hypochlorite was used to suppress diacetoxyscirpenol cutaneous toxicity; mice skin can be decontaminated with "Eau de Javel" (1 p. 100 free chlorine) if application is performed less than 15 min. after contact with toxin.