Efficacy of Chlorine Dioxide as an Endodontic Irrigant for Pulp Dissolution in vitro

Determine the efficacy of 5 % chlorine dioxide as an endodontic irrigant for pulp dissolution. Thirty five samples of human dental pulp were obtained, previously weighed and immersed in three solutions= 5 % ClO 2, 5.25 % NaOCl and saline (control group), for 10 minutes at 32 ºC; they were dried and reweighed. Then the weight loss was compared to the original weight and analyzed statistically. 5.25 % NaOCl and 5 % ClO 2 dissolved the dental pulp samples more effectively than saline (p> 0.001). No statistically significant difference was found between the tissue dissolving proper ties of 5.25 % NaOCl and 5 % ClO2 (p=0.893). 5 % ClO2 is effective in dissolving human dental pulp tissue.

El objetivo de este estudio fue determinar la eficacia del dióxido de cloro al 5 % como irrigante endodóntico para la disolución pulpar. Se obtuvieron 35 muestras de pulpa dental humana, se pesaron previamente y se sumergieron en tres soluciones= 5 % ClO2, 5.25 % NaOCl y suero fisiológico (grupo control), durante 10 minutos a 32ºC; se secaron y se pesaron de nuevo. Luego se comparó la pérdida de peso del peso original y se analizó estadísticamente. NaOCl al 5.25 % y ClO2 al 5 % disolvieron las muestras de pulpa dental con más eficacia que el suero fisiológico (p> 0.001). No se encontró diferencias estadísticamente significativas entre las propiedades de disolución de tejido de NaOCl al 5.25 % y ClO2 al 5 % (p=0.893) ClO2 al 5 % es eficaz para disolver tejido de pulpa dental humana.

Dióxido de cloro: la verdad toxicológica y el riesgo de las noticias falsas

El dióxido de cloro es una sustancia que se ha usado como desinfectante para tratar el agua de consumo humano. A las dosis usadas en este escenario no se han asociado compromisos toxicológicos para el ser humano. Químicamente, el dióxido de cloro se caracteriza por reaccionar con diversas moléculas y generar estrés oxidativo en los microorganismos y en las células. A pesar de no ser un medicamento ni estar aprobado por las agencias reguladoras, se ha promovido su uso como una solución milagrosa; sin embargo, no hay ninguna evidencia científica que lo respalde. De otro lado, sí hay evidencia de que puede generar toxicidad aguda, y posiblemente crónica, para el ser humano.

Summary Chlorine dioxide has been used as a disinfectant to treat water for human consumption, at the doses used in this scenario, human poisoning has not been described. Chemically, chlorine dioxide is characterized by reacting with various molecules, and generating oxidative stress in microorganisms, and in human cells. Chlorine dioxide is not a medicine, and it is not approved by regulatory agencies. Chlorine dioxide has been promoted as a miracle solution, yet there is no scientific evidence to back it up. On the other hand, there is evidence, that it can generate acute poisoning and possibly chronic poisoning in humans.

Could polyhexanide and chlorine dioxide be used as an alternative to chlorhexidine? A systematic review

ABSTRACT BACKGROUND: Maintenance of oral microbiota balance is the simplest way to prevent infectious oral diseases, through controlling dental biofilm. Combined use of mouthwash and mechanical removal has been shown to be a very effective way for this. OBJECTIVES: To identify clinical studies comparing the antimicrobial effect and possible adverse effects and/or side effects of chlorhexidine-based mouthwashes with those of mouthwashes containing chlorine dioxide and/or polyhexanide, for controlling oral microbiota. DESIGN AND SETTING: Systematic review designed by the stomatology sector of postgraduation in applied dental sciences of Bauru Dentistry School, University of São Paulo, Brazil. METHODS: A systematic review was conducted using online databases (PubMed, Embase, Web of Science and Science Direct) up to April 8, 2020. The search was conducted using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. RESULTS: The studies included comprised eight articles published between 2001 and 2017. A total of 295 young adults, adults and elderly people were evaluated (males 44.75% and females 55.25%). Three articles compared polyhexanide with chlorhexidine and five articles compared chlorine dioxide with chlorhexidine. No studies comparing all three mouthwashes were found. The concentrations of the study solutions were quite varied, and all rinses had an antimicrobial effect. In four studies, it was stated that no side effects or adverse effects had been found. Three studies did not address these results and only one study addressed side effects and/or adverse effects. CONCLUSION: Mouthwashes containing chlorine dioxide and polyhexanide are viable alternatives to chlorhexidine, since they reduce oral biofilm and have little or no reported side or adverse effects.

Tendencias de búsqueda en Internet sobre dióxido de cloro en ocho países de Latinoamérica durante la pandemia por COVID-19 / Trends of Internet search about chlorine dioxide in eight Latin American countries during the COVID-19 pandemic

La infodemiología e infovigilancia son métodos informáticos para el análisis y seguimiento de los datos de Internet, y permiten tomar conciencia de las situaciones y crear políticas sanitarias. Este estudio se propuso analizar las tendencias de búsqueda de dióxido de cloro y términos equivalentes en Internet (chlorine dioxide solution, CDS; miracle mineral solution, MMS), en relación con la morbilidad y mortalidad por COVID-19 en ocho países de Latinoamérica. Para ello se utilizó Google Trends; el período examinado fue del 1ro de marzo al 25 de noviembre de 2020. Se calculó la media móvil por 7 días para el volumen relativo de búsqueda (VRB), la tasa de morbilidad y mortalidad. Para la asociación de las variables cuantitativas, se utilizó el coeficiente de correlación de Spearman con un nivel de significancia p < 0,05. El país con mayor interés de búsqueda fue Bolivia; el de menor interés, Brasil. El análisis del VRB con la tasa de morbilidad y mortalidad fue diferente entre países. Los picos máximos de VRB de Colombia y Chile, en abril, y de México, Ecuador y Bolivia, en julio, coincidieron con la emisión de alertas sanitarias sobre dióxido de cloro. La mayoría mostró una correlación significativa moderada y baja entre el VRB y el número de casos confirmados y muertes diarias por COVID-19. El comportamiento de las búsquedas, diferenciado entre países, podría indicar mayor interés por el tema dióxido de cloro en pandemia; lo cual se explicaría por la difusión de alertas sanitarias de organismos de salud internacionales, regionales y locales(AU)

Infodemiology and infovigilance are computer methods for the analysis and monitoring of Internet data, and allow awareness of situations and creation of health policies. This study aimed to analyze the search trends for chlorine dioxide and equivalent terms on the Internet (chlorine dioxide solution, CDS; miracle mineral solution, MMS), in relation to COVID-19 morbidity and mortality in eight Latin American countries. Google Trends was used for this purpose; the period reviewed was from March 1st to November 25th 2020. The 7-day moving average for relative search volume (VRB), morbidity and mortality rate were calculated. For the association of quantitative variables, the Spearman correlation coefficient was used with a significance level p < 0.05. The country with the highest search interest was Bolivia; the one with the least interest, Brazil. The analysis of the VRB with the morbidity and mortality rate was different between countries. The maximum VRB peaks of Colombia and Chile, in April, and of Mexico, Ecuador and Bolivia, in July, coincided with the issuance of health alerts on chlorine dioxide. Most showed a moderate and low significant correlation between VRB and the number of confirmed cases and daily deaths from COVID-19. The behavior of the searches, differentiated between countries, could indicate greater interest in the topic of chlorine dioxide during the pandemic; this would be explained by the dissemination of health alerts from international, regional and local health agencies(AU)

Guía de actuación y abordaje frente a intoxicación por dióxido de cloro/clorito de sodio, a partir de la experiencia de los CIAT de América Latina / Guidelines for action and approach to chlorine dioxide/sodium chlorite poisoning based on the experience of the CIATs in Latin America

Resumen El 11 de marzo de 2020, la Organización Mundial de la Salud, declaró la pandemia a nivel mundial por la COVID-19. Ante este escenario, los centros de información y asesoramiento toxicológico (CIAT) de América Latina comenzaron a recibir consultas por exposición/intoxicación a dióxido de cloro/clorito de sodio y sus compuestos relacionados, por desvío de uso, destinado a la prevención y/o tratamiento de la COVID-19 sin aval científico alguno ni contar con registro sanitario para ese fin. A través de la Red de Toxicología de América Latina y el Caribe (RETOXLAC), se comprobó que no eran hechos aislados, sino que se estaba produ ciendo el mismo fenómeno en toda la región y que existían antecedentes de intoxicaciones con dichos productos y alertas desde hace más de una década, con indicaciones no aprobadas, para el tratamiento de distintas patologías como SIDA, cáncer, esclerosis lateral amiotrófica ELA, malaria, autismo, entre otras, sin evidencia. Ante esta realidad, los CIAT presentan una revisión de los signos y síntomas observados según la vía de ingreso, basados en la comunicación de riesgo en salud; proponiéndose pruebas de apoyo al diagnóstico, algoritmo de tratamiento para las intoxicaciones y modelo de ficha clínica para la vigilancia epidemiológica de los casos atendidos. Recomendamos a las autoridades y organismos responsables, reforzar las acciones tendientes a la vigilancia, control y prevención de este tipo de intoxicaciones, producto del mal uso de un desinfectante no autorizado para fines terapéuticos/médicos.

Abstract On March 11th, 2020, the World Health Organization declared a global pandemic due to COVID-19. Faced with this sce- nario, the Poison Control Centers (CIATs for its initials in spanish) in Latin America began to receive consultations for exposure/poi- soning to chlorine dioxide/sodium chlorite and its related compounds for their use aimed to prevent or treat COVID-19 without any scientific endorsement or having a sanitary registry for that purpose. It was found through the Toxicology Network of Latin America and the Caribbean (RETOXLAC) that they were not isolated events but rather that the same phenomenon was occurring throughout the region and that there has been a history of poisoning and alerts with these products for more than a decade with unapproved indications for the treatment of different pathologies such as AIDS, cancer, amyotrophic lateral sclerosis (ALS), malaria, autism, among others, without evidence. In the light of this situation, the CIATs present a review of the signs and symptoms observed ac- cording to the route of exposure based on health risk communication; proposing tests to support the diagnosis, an algorithm for poisoning treatment, and a model of a clinical record for the epidemiological surveillance of the assisted cases. We recommend to the authorities and responsible organisms reinforce the actions aimed at surveillance, control, and prevention of this type of poisoning due to the misuse of an unauthorized disinfectant for therapeutic or medical purposes.

Enfoque de tratamiento integral del paciente intoxicado por dióxido de cloro y derivados del cloro / Comprehensive therapy approach for patients affected by chloride dioxide and chlorine derivative poisoning

RESUMEN Durante la emergencia sanitaria debida al SARS-CoV-2 y ante la ausencia de una terapéutica específica surgieron tratamientos sin evidencia científica, conllevando a un contexto de infodemia sobre el uso de dióxido de cloro y derivados del cloro, cuyas medidas de elaboración, distribución y administración no son reguladas, exponiendo a un gran número de personas a dicho producto pudiendo llevar a contextos de intoxicación y muerte. En este escenario el artículo presentado tiene el objetivo de brindar al personal de salud, un enfoque de tratamiento integral del paciente intoxicado por estos productos a nivel prehospitalario, que consiste en realizar un protocolo donde se valore el escenario de la exposición del paciente (uso de equipo de protección personal, triaje, descontaminación, entre otros), se realice la evaluación primaria y una evaluación secundaria (revaloración continua del paciente) y a nivel hospitalario (evaluación sistemática del paciente, identificación de la vía de exposición y aplicación de uso de antídoto en escenarios específicos); así como medidas de prevención tanto para el personal de salud como para la población general.

ABSTRACT During the sanitary emergency due to SARS-CoV-2, and considering the absence of specific therapy against this condition, many therapy approaches with no underlying scientific evidence appeared, leading to infodemics with many publications about the use of chloride dioxide and chlorine derivatives, without any regulation on manufacturing, distribution, and administration of such products; and so many people developed multiple symptoms, leading to intoxication and death. In this context, this paper aims to offer healthcare personnel, a comprehensive pre-hospital therapy approach for patients affected by the aforementioned compounds. The idea is to perform a protocol where the scenario for patients' exposure is determined (use of personal protective equipment, triage, decontamination, and the like), primary and secondary assessments are to be performed (continuously reassessing the affected patient). Later, hospital management is to be performed (systematic patient's assessment, identifying the exposure route and use of an antidote when necessary for specific cases); and establishing prevention measures for both healthcare personnel and the general population.

Dióxido de cloro y su repercusión en las tendencias de búsquedas en internet durante la pandemia por la COVID-19 / Chlorine dioxide: its impact on internet search trends in times of COVID-19 / Dióxido de cloro e seu impacto nas tendências de pesquisa da Internet durante a pandemia de COVID-19

RESUMEN Introducción: El creciente número de casos de COVID-19 a nivel mundial han dado paso al deterioro de la de salud mental y la investigación de nuevos tratamientos; esto ha dado lugar a una explosión de búsquedas en internet de palabras clave. Objetivo: En esta investigación se ha descrito el uso de Google Trends para medir las búsquedas en internet de términos asociados a la pandemia por COVID-19 en distintas regiones de Perú y su potencial para realizar investigaciones en salud. Método: Se midió la tendencia de búsquedas en internet del término "dioxido de cloro" en el período entre el 3 de junio al 3 de septiembre de 2020. Se utilizaron los datos de Google Trends sobre una fracción de las búsquedas de las palabras clave, y se analizaron los resultados de acuerdo con una ubicación geográfica dada y un período definido. Resultados: Se encontró que los países que presentaron mayor nivel de búsqueda para dicho término fueron Bolivia, Perú, Ecuador, Argentina y México. Se encontró correlación positiva alta entre el nivel de búsqueda en Argentina y el número de casos en este país, a comparación de Perú, Ecuador y México, donde la correlación fue positiva muy baja. En el caso de Bolivia, se presentó una correlación negativa muy baja. Google Trends podría, además, definir potencialmente el momento y la ubicación adecuada para practicar estrategias de comunicación de riesgos a las poblaciones afectadas. Conclusiones: Existe correlación entre en número de casos y las búsquedas de dióxido de cloro como medida médica contra la COVID-19.

ABSTRACT Introduction: The increasing worldwide number of cases of COVID-19 has led to the deterioration of mental health and researches of new treatments; this has resulted in an explosion of keyword searches on Internet. Objective: This research has described the use of Google Trends to measure the search queries in internet for terms associated with the COVID-19 pandemic in different regions of Peru as well as its potential to conduct research on health aspects. Method: It was measured the search trends in internet for the term "chlorine dioxide" in the period from June 3 to September 3, 2020. Google trends data were used on a fraction of the keyword searches, and the outcomes were analyzed according to the geographic location and defined period. Results: It was found a higher tendency of searching related terms in Bolivia, Perú, Ecuador, Argentina, and México. A high positive correlation was found between the level of search in Argentina and the number of COVID-19 cases in this country, unlike Peru, Ecuador and Mexico, where the correlation was very low. Instead, in Bolivia there was a very low negative correlation. Google Trends could also potentially define the appropriate time and location to practice risk communication strategies to affected populations. Conclusions: An appropriate risk communication could help to prevent the excessive information intakes, which often causes concern or panic in different populations.

RESUMO Introdução: O crescente número de casos de COVID-19 em todo o mundo tem dado lugar à deterioração da saúde mental e à investigação de novos tratamentos; Isso levou a uma explosão de pesquisas de palavras-chave na Internet. Objetivo: Esta pesquisa descreveu o uso do Google Trends para medir buscas na internet por termos associados à pandemia COVID-19 em diferentes regiões do Peru e seu potencial para a realização de pesquisas em saúde. Método: A tendência das pesquisas na internet do termo "dióxido de cloro" foi medida no período entre 3 de junho e 3 de setembro de 2020. Os dados do Google Trends foram usados ​​em uma fração das pesquisas pelas palavras-chave, e os resultados foram analisados ​​de acordo com uma determinada localização geográfica e um período definido. Resultados: Constatou-se que os países com maior nível de busca por esse termo foram Bolívia, Peru, Equador, Argentina e México. Foi encontrada uma alta correlação positiva entre o nível de pesquisa na Argentina e o número de casos neste país, em comparação com Peru, Equador e México, onde a correlação foi muito baixa positiva. No caso da Bolívia, houve uma correlação negativa muito baixa. O Google Trends também pode definir o momento e o local certos para praticar estratégias de comunicação de risco para as populações afetadas. Conclusões: Há correlação entre o número de casos e as pesquisas de dióxido de cloro como medida médica contra o COVID-19.

Dióxido de cloro y derivados del cloro para prevenir o tratar la COVID-19: revisión sistemática / Chlorine dioxide and chlorine derivatives for the prevention or treatment of COVID-19: a systematic review

RESUMEN Objetivos: Realizar una revisión sistemática acerca de la efectividad y seguridad del uso de dióxido de cloro y derivados del cloro, en la prevención o el tratamiento de la COVID-19. Materiales y métodos: Se siguieron las pautas internacionales de elaboración de revisiones sistemáticas de PRISMA y el Manual Cochrane para revisiones sistemáticas de intervenciones. La estrategia de búsqueda la desarrolló un bibliotecario y la revisaron dos de los autores. Se complementó la búsqueda electrónica con una búsqueda manual. Se incluyeron ensayos clínicos aleatorizados, estudios cuasiexperimentales, estudios de cohorte, estudios de casos y controles, estudios de corte transversal y reportes de casos; y se excluyeron estudios in vitro o realizados en animales. Dos revisores, de forma independiente, seleccionaron los estudios según los criterios de elegibilidad definidos, usando el aplicativo web Rayyan, en caso de discordancia se hizo partícipe a un tercer revisor. El protocolo de la revisión sistemática se registró en PROSPERO (CRD42020200641). Resultados: No se identificó ningún estudio publicado ni en proceso de publicación que haya evaluado el uso del dióxido de cloro o derivados del cloro, administrado por vía inhalatoria, oral o parenteral en humanos, como agente preventivo o terapéutico de la COVID-19 o en infecciones por otros coronavirus. Solo se identificó el registro de un único estudio catalogado como observacional que hasta ahora no tiene resultados. Conclusiones: A la fecha, no existe evidencia científica que apoye el uso del dióxido de cloro o derivados del cloro para prevenir o tratar la COVID-19.

ABSTRACT Objectives: To systematically review the effectiveness and safety of chlorine dioxide solution and chlorine derivatives used in the prevention or treatment of COVID-19. Methods: This review adheres to the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) and follows the guidelines provided in the Cochrane Handbook for Systematic Reviews of Interventions. A librarian developed and executed the search strategy; it was further reviewed by two of the authors and complemented by manual search. Randomized clinical trials, quasi-experimental studies, cohort studies, case-control studies, cross-sectional studies, and case reports were included; in vitro or animal studies were excluded. Abstract and full-text screening according to pre-defined eligibility criteria were performed by two reviewers independently using web application Rayyan QCRI. Disagreements on study selection were resolved by a third reviewer. The systematic review protocol was registered in PROSPERO (CRD42020200641). Results: Neither published nor pre-print studies evaluating the use of chlorine dioxide or derivatives on SARS-CoV-2 infection were identified. The only finding was an unpublished observational study registry which has no results released yet. Conclusions: To date, there are no scientific evidence to uphold the use of chlorine dioxide or derivatives as preventive or therapeutic agents against COVID-19.

Caracterización epidemiológica de las exposiciones a dióxido de cloro/clorito de sodio en el contexto de la pandemia COVID-19: Reporte de los centros toxicológicos de América Latina / Epidemiological characterization of exposures to chlorine dioxide/ sodium chlorite in the context of the COVID-19 pandemic: Report of Poison Control Centers in Latin America

Resumen Los centros de información y asesoramiento toxicológico CIATs de América Latina, en el contexto de la pandemia de COVID-19, recibieron una serie de llamadas para consultas y asesoramientos relacionados con el uso de dióxido de cloro/clorito de sodio, que se estaban empleando en el tratamiento o prevención de dicha enfermedad. Dentro de la legislación vigente en los países de América Latina, no se contemplan productos farmacéuticos registrados para uso en humanos, ni se tiene evidencia de registros sanitarios en Europa, Canadá o Estados Unidos para tal fin, que contengan dióxido de cloro o clorito de sodio. Esta publicación, compila la información registrada como parte de la estadística del trabajo de ocho CIATs correspondientes a igual número de países de América Latina. Se identificó sexo, edad, sintomatología, circunstancia y grado de severidad de los 56 casos de pacientes intoxicados con dióxido de cloro/clorito de sodio registrados en el período del 15 de marzo al 30 de septiembre de 2020 en estos ocho países. Los resultados obtenidos confirman que la causa más común fue por mal uso, y el lugar de ocurrencia fue el hogar o sus alrededores, siendo el mayor porcentaje adultos jóvenes comprendidos entre 30 y 49 años. Los síntomas de intoxicación más frecuentemente encontrados fueron gastrointestinales, seguidos de cardiovasculares y respiratorios. La vía de ingreso al organismo en la mayoría de los casos fue por vía oral, reportándose algunos casos por vía inhalatoria, y en el 50% de los casos se constituyeron casos de severidad moderada, severa o fatal (3 fallecimientos). Este estudio contribuye a generar información relevante para las diferentes autoridades sanitarias, los ministerios de salud, las entidades encargadas de inspección, vigilancia y control de los países en los que se comercializan estos productos de manera ilegal por medio de redes sociales y promoviéndolos para uso en humanos para prevenir o curar COVID-19.

Abstract The Poison Control Centers in Latin America, in the context of COVID-19 pandemic, received a series of calls for consultations and recommendations related to the use of chlorine dioxide/sodium chlorite, in the treatment or prevention of CO-VID-19. Under current legislation in Latin America, no pharmaceutical products are registered for use in humans that contain chlorine dioxide or sodium chlorite, nor is there evidence of sanitary registries in Europe, Canada, or the United States for this purpose. This publication compiles the information registered by eight Poison Control Centers that correspond to the same number of Latin American countries. Sex, age, symptoms, circumstance, and degree of severity of the 56 cases of patients poisoned with chlorine dioxide/ sodium chlorite registered in the period from March 15th to September 30th, 2020 were identified. The results obtained confirm that the most common cause of poisoning was unintentional misuse, all of which occurred at home or its surroundings, with the highest percentage of registered cases being young adults between 30 and 49 years old. The most frequent symptoms of intoxication were gastrointestinal, followed by cardiovascular and respiratory. The route of exposure in most cases was oral, with some cases reported by inhalation; 48.2% of the cases were of moderate, severe, or fatal (3 deaths). This study contributes to the generation of relevant information for different health authorities, ministries of health, entities in charge of inspection, surveillance, and control in countries where these products are illegally marketed through social networks and promoted for use in humans to prevent or cure COVID-19.

A Comparison of the Bleaching Effectiveness of Chlorine Dioxide and Hydrogen Peroxide on Dental Composite

This study was carried out to verify if composites could be bleached using chlorine dioxide as compared with hydrogen peroxide. 3M ESPE Filtek Z350 Universal Restorative discs were prepared (n=40), with dimensions 5 mm diameter x 2 mm thickness. The discs were divided into 4 groups of 10 discs each. Color assessment was performed by CIEDE2000. The discs were stained with coffee, tea, wine and distilled water (control) solutions for 14 days, 5 hours daily. Color assessment was repeated on stained discs and followed by bleaching of 5 discs from each group using chlorine dioxide and hydrogen peroxide in-office systems. Finally, a last color assessment was performed and compared statistically. DE2000 after bleaching was very close to baseline for both the bleaching agents, although chlorine dioxide showed better results than hydrogen peroxide. After staining, there was a clinically significant discoloration (∆E2000≥3.43) for the tea, coffee and wine groups, and discoloration (∆E2000) was seen more in the wine group as compared to tea and coffee. Overall, the control group (distilled water) had the least color change in the three intervals. After bleaching, the color in all specimens returned close to the baseline. The color differences between bleaching and baseline were less than 3.43 for all groups. The obtained results show that chlorine dioxide is slightly superior to hydrogen peroxide in the bleaching of composites, while maintaining the shade of the composite close to the baseline.

Este estudo foi realizado para verificar se resinas compostas podem ser clareadas com uso do dióxido de cloro, em comparação com peróxido de hidrogênio. Foram preparados discos com resina restauradora Filtek Z350 3M ESPE (n=40), com dimensões 5 mm de diâmetro × 2 mm de espessura. Os discos foram divididos em 4 grupos de 10 discos cada. A avaliação da cor foi realizada por meio do CIEDE2000. Os discos foram manchados com soluções de café, chá, vinho e água destilada (controle) por 5 h diárias durante 14 dias. A avaliação da cor foi repetida nos discos manchados e seguida por clareamento de 5 discos de cada grupo, utilizando dióxido de cloro ou peróxido de hidrogênio pela técnica de consultório. Finalmente, uma última avaliação da cor foi realizada e as técnicas comparadas estatisticamente. DE2000 após o clareamento foi muito próxima ao baseline, para ambos os agentes clareadores, embora o dióxido de cloro tenha mostrado melhores resultados do que o peróxido de hidrogênio. Após o manchamento, houve uma descoloração clinicamente significativa (ΔE2000≥3,43) para os grupos de chá, café e vinho, sendo que o clareamento (ΔE2000) foi melhor obtido com o grupo do vinho, em comparação com chá e café. No geral, o grupo controle (água destilada) teve a menor mudança de cor nos três intervalos. Após o clareamento, a cor em todos os espécimes voltou próxima ao baseline. As diferenças de cor entre o clareamento e o baseline foram inferiores a 3,43 para todos os grupos. Os resultados indicam que o dióxido de cloro é ligeiramente superior ao peróxido de hidrogênio no clareamento de resinas compostas, mantendo a cor próxima à escala do baseline.

Alternative sanitization methods for minimally processed lettuce in comparison to sodium hypochlorite

Lettuce is a leafy vegetable widely used in industry for minimally processed products, in which the step of sanitization is the crucial moment for ensuring a safe food for consumption. Chlorinated compounds, mainly sodium hypochlorite, are the most used in Brazil, but the formation of trihalomethanes from this sanitizer is a drawback. Then, the search for alternative methods to sodium hypochlorite has been emerging as a matter of great interest. The suitability of chlorine dioxide (60 mg L-1/10 min), peracetic acid (100 mg L-1/15 min) and ozonated water (1.2 mg L-1 /1 min) as alternative sanitizers to sodium hypochlorite (150 mg L-1 free chlorine/15 min) were evaluated. Minimally processed lettuce washed with tap water for 1 min was used as a control. Microbiological analyses were performed in triplicate, before and after sanitization, and at 3, 6, 9 and 12 days of storage at 2 ± 1 ºC with the product packaged on LDPE bags of 60 µm. It was evaluated total coliforms, Escherichia coli, Salmonella spp., psicrotrophic and mesophilic bacteria, yeasts and molds. All samples of minimally processed lettuce showed absence of E. coli and Salmonella spp. The treatments of chlorine dioxide, peracetic acid and ozonated water promoted reduction of 2.5, 1.1 and 0.7 log cycle, respectively, on count of microbial load of minimally processed product and can be used as substitutes for sodium hypochlorite. These alternative compounds promoted a shelf-life of six days to minimally processed lettuce, while the shelf-life with sodium hypochlorite was 12 days.

Pré-oxidação e adsorção em carvão ativado granular para remoção dos herbicidas Diuron e Hexazinona de água subterrânea / Preoxidation and adsorption in granular activated carbon for the removal of Diuron and Hexazinone from groundwater

O cultivo da cana-de-açúcar exige a utilização de herbicidas, destacando-se o Diuron e a Hexazinona. Alguns dos poços de abastecimento de Ribeirão Preto (SP) construídos no Aquífero Guarani estão situados em pontos de recarga, e a presença de solo de textura arenosa nessas áreas aumenta a vulnerabilidade da água subterrânea à contaminação por herbicidas. Neste trabalho foram monitorados alguns poços localizados na área de recarga e estudou-se a remoção de Diuron e Hexazinona por meio da adsorção em carvão ativado granular (CAG) e da pré-oxidação com cloro e dióxido de cloro em uma instalação piloto de escoamento contínuo. Verificou-se que o tempo de saturação do CAG no ensaio com a pré-oxidação foi inferior ao obtido no ensaio sem a pré-oxidação com ambos os oxidantes, possivelmente pela formação de subprodutos que competiram com a adsorção dos herbicidas.

The cultivation of sugarcane demands the use of herbicides such as Diuron and Hexazinone. Some supply wells from Ribeirão Preto, SP, Brazil, built in the Guarani Aquifer are located in recharge points, and the presence of sandy Quartzarenic Neosol in these areas increases the vulnerability of the groundwater to contamination from herbicides This paper reports the water quality monitored in some wells located in the recharge area and the removal of Diuron and Hexazinone by means of adsorption in granular activated carbon (GAC), preceded or not by preoxidation with chlorine and chlorine dioxide in a pilot plant. The results indicated that Diuron was more strongly adsorbed than Hexazinone and that the saturation time of the GAC in the test with preoxidation was shorter than in the test without preoxidation, which may have occurred mainly due to the formation of by-products that competed with the adsorption of the herbicides.

Evaluation of A Chlorine Dioxide Disinfectant for Dental Unit Waterlines / 中华医院感染学杂志

OBJECTIVE To investigate the use of a chlorine dioxide-based dental unit waterline(DUWL) treatment to reduce the colonization and growth of heterotrophic bacteria.METHODS Twenty-two dental units with self-contained water systems were randomly selected.Three of the units and tap water served as controls.Twenty-three water samples were taken at baseline and once a week for five weeks.They were serially diluted,spread-plated in duplicate onto R2A agar plates and incubated at 37 ℃ for 7 days.RESULTS At baseline,the 3 control DUWLs had a median count of 8440 colony-forming units/milliliter(CFU/ml) and the 19 treated DUWLs had a median count of 9160 CFU/ml.By week 1,18 of the 19 treated DUWLs had counts of less than 200 CFU/ml,and by week 4,the median count for all of the treated DUWLs was 0 CFU/ml.The measurement at week 5 showed that the reduction to below 200 CFU/ml had been maintained.Scanning electron examination revealed a similar results,with biofilm accumulation more evident in the untreated control specimens.CONCLUSIONS Using a chlorine dioxide-based disinfectant in DUWLs can achieve the American Dental Association(ADA) goal of less than 200 CFU/ml of heterotrophic bacteria per milliliter of unfiltered output water.

Chlorine dioxide against bacteria and yeasts from the alcoholic fermentation / Dióxido de cloro contra bactérias e leveduras da fermentação alcoólica

The ethanol production in Brazil is carried out by fed-batch or continuous process with cell recycle, in such way that bacterial contaminants are also recycled and may be troublesome due to the substrate competition. Addition of sulphuric acid when inoculum cells are washed can control the bacterial growth or alternatively biocides are used. This work aimed to verify the effect of chlorine dioxide, a well-known biocide for bacterial decontamination of water and equipments, against contaminant bacteria (Bacillus subtilis, Lactobacillus plantarum, Lactobacillus fermentum and Leuconostoc mesenteroides) from alcoholic fermentation, through the method of minimum inhibitory concentration (MIC), as well as its effect on the industrial yeast inoculum. Lower MIC was found for B. subtilis (10 ppm) and Leuconostoc mesenteroides (50 ppm) than for Lactobacillus fermentum (75 ppm) and Lactobacillus plantarum (125 ppm). Additionally, these concentrations of chlorine dioxide had similar effects on bacteria as 3 ppm of Kamoran® (recommended dosage for fermentation tanks), exception for B. subtilis, which could not be controlled at this Kamoran® dosage. The growth of industrial yeasts was affected when the concentration of chlorine dioxide was higher than 50 ppm, but the effect was slightly dependent on the type of yeast strain. Smooth yeast colonies (dispersed cells) seemed to be more sensitive than wrinkled yeast colonies (clustered cells/pseudohyphal growth), both isolated from an alcohol-producing unit during the 2006/2007 sugar cane harvest. The main advantage in the usage of chlorine dioxide that it can replace antibiotics, avoiding the selection of resistant populations of microorganisms.

A produção de etanol no Brasil é atualmente realizada pelo processo de fermentação em batelada alimentada ou contínuo, com reciclo de células de leveduras, de forma que contaminantes bacterianos são também reciclados e podem causar problemas devido à competição pelo mesmo substrato. O controle bacteriano é feito pela adição de ácido sulfúrico na lavagem das células do fermento ou utilizando-se biocidas. O objetivo do trabalho foi verificar o efeito do dióxido de cloro, um biocida muito utilizado para a descontaminação da água e equipamentos, contra bactérias contaminantes da fermentação alcoólica (Bacillus subtilis, Lactobacillus plantarum, Lactobacillus fermentum e Leuconostoc mesenteroides), através do método da concentração inibitória mínima (CIM), assim como seu efeito sobre o fermento industrial. Valores menores de CIM foram encontrados para Bacillus subtilis (10 ppm) e Leuconostoc mesenteroides (50 ppm) do que para Lactobacillus fermentum (75 ppm) e Lactobacillus plantarum (125 ppm). Estas concentrações tiveram o mesmo efeito inibidor que 3 ppm de Kamoran®, com exceção de B. subtilis, no qual não se observou inibição de crescimento à esta concentração. As leveduras industriais apresentaram inibição no crescimento em concentrações superiores a 50 ppm, porém esta pareceu ser dependente do tipo de linhagem de levedura. Colônias cremosas (células dispersas) foram ligeiramente mais sensíveis que as colônias rugosas (células agrupadas/pseudohifas), ambas isoladas de uma unidade produtora de álcool durante a safra de cana-de-açúcar 2006/2007. A principal vantagem na utilização deste produto está na eliminação do uso de antibióticos, evitando a geração de populações resistentes de microrganismos.

Avaliação de tecnologias avançadas para o reúso de água em indústria metal-mecânica / Evaluation of advanced technologies for water reuse in mechanical industry

Com o objetivo de reduzir o consumo de água e o descarte do efluente tratado de uma indústria metal-mecânica foi proposta a avaliação técnica e econômica de cinco tecnologias de tratamento que pudessem proporcionar a reutilização do efluente. Foram levantados quatro locais para reúso e sugeridos critérios para cada um deles. Foi constatado que na adsor-ção com carvão ativado e na osmose reversa o efluente tratado por estes processos poderia ser reutilizado nos locais propostos e, com vazão de reúso de 2,5m³/h, os custos ficaram em US$ 1,14/m³ e US$ 1,70/m³ respectivamente. Para o ozônio e o dióxido de cloro, mesmo desinfetando o efluente, obteve-se apenas resultados satisfatórios, com custo de US$ 0,54/m³ e US$ 0,71/m³ respectivamente. Na coagulação/floculação todos os parâmetros analisados atenderam a dois locais de reúso, com exceção dos SDT e se obteve custo de US$ 1,57/m³

With the objective to reduce the water consumption and the discharge of effluents in a metal industry, a technical and economical evaluation of five treatment technologies was proposed in order to reuse the effluents. Four sites for water reuse were chosen and for each of them criteria were suggested. It was evidenced that in the adsorption with activated carbon and reverse osmosis the effluent treated by these processes could be reused and, with the flowrate projected of 2.5m³/h, the cost attained US$ 1.14/m³ and US$ 1.70/m³ respectively. For the ozone and chlorine dioxide, even so the effluent was disinfected, gave only satisfactory results and the cost attained US$ 0.54/m³ and US$ 0.71/m³ respectively. For the treatment with coagulation/flocculation, all the analyzed parameters were successful in two reuse places, with exception of the TDS. The cost for this technology attained US$ 1.57/m³

Methods for Components in Chlorine Dioxide Disinfectant / 环境与健康杂志

Objective In order to evaluate the quality and performance of chlorine dioxide disinfectant,it is necessary to develop a set of methods to determine the components in chlorine dioxide disinfectant.Methods Iodometry,malonic acid iodometry,improved malonic acid iodometry and five-step iodometry were employed to determine the components including ClO_2, Cl_2,ClO_2~-,and ClO_3~-in chlorine dioxide disinfectant,the advantages and disadvantages of the test methods were compared.Results Using iodometry,the liquid stabilized chlorine dioxide products activated by hydrochloric acid,the content of ClO_2 was 20.23 mg/ml that was accord with the content which was marked in the product label.Using malonic acid iodometriy,the liquid stabilized chlorine dioxide contents of ClO_2 was 19.99 mg/ml,Cl_2 was 0.35 mg/ml,in which a little chlorine was detected.Using improved malonate iodometry and five-step iodometry,the activation rates of the liquid stabilized chlorine dioxide products were 88.0% and 75.6% respectively,ClO_2 and ClO_2~-in the liquid stabilized chlorine dioxide products could be distinguished.Conclusion Active chlorine dioxide and residual ClO_2~-can be detected by using iodometriy and improved malonic acid iodometry,but iodometriy and malonic acid iodometry can not.

Investigation on the Performance of Chlorine Dioxide Generators for Drinking Water Disinfection / 环境与健康杂志

Objective To preliminarily investigate the conditions of the performance of chlorine dioxide generator for drinking water disinfection and know the overall situation of the industry.Methods From 2007 to 2008,6 companies'products were chosen for this investigation according to certain rules,and their performance indicators,such as chlorine dioxide output and conversion rate were tested by using the Five-step iodimetry method.Results On-site generating technology was commonly used,and the average conversion rate of the compound type generator was 57.06%,and the pure type generator was 84.78%.Conclusion The conversion rate of the pure type generator is better than the compound type,and the newly invented pure type generator has much better performance and lower disinfection cost.

Priliminary Study on Chlorite Pollution of Drinking Water Disinfected by Chlorine Dioxide / 环境与健康杂志

[Objective] To explore the status of chlorite pollution in drinking water due to chlorine dioxide , aswell as its causes and counter measures. [Methods]A water plant collecting surface water as raw water slightly pol-luted by organic compounds and B water plant collecting ground water without organic compounds pollution wereselected as observed objectives. Chlorine dioxide generators were used in both of A and B water plants, their rawmaterials was chlorite for A plant and chlorate for B plant. The levels of chlorite in treated water from these twowater plants were determined by amperometric titration. [Results]The levels of chlorite in treated water of A waterplant ranged 0.530～0.760 mg/L, 2.6～3.8 times of the standard value, with a over standard rate of 100％, thelevels of B water plant range 0.257～0.733 mg/L, 1.3～3.7 times of the standard value, with a over standard rateof 83.3％. [Conclusion] The treated water of A and B water plants presented higher pollution by chlorite, the by-product of chlorine dioxide disinfection.

Air Disinfection with Chlorine Dioxide in Saps / 环境与健康杂志

Objective To observe the effect of air disinfection with chlorine dioxide(ClO2)in the saps and determine the concentration change in order to ensure the safety for people to enter the saps.Methods The disinfection was done at the concentration of 1 000 mg/L and the spray dose of 10 ml/m3 and then to count the total bacteria and fungi with the cascade impactors in the saps before and after air disinfection and to monitor the concentration of ClO2 with the air ClO2 monitor(iTX).Results The 94.6% of the total bacteria and 92.1% of the fungi died in 30 minutes after disinfection.The concentration of ClO2 in the air decreased from 10 mg/m3 to 0.8 mg/m3 81 minutes later and to 0.3 mg/m3 96 minutes later,after 120 minutes,it was 0 mg/m3.Conclusion The air disinfection effect of ClO2 used at the dose of 10 ml/m3 and the concentration of 1 000 mg/L is satisfactory.96 minutes after disinfection,the concentration of ClO2 is safe for human health.

Disinfection of Waste water of Hospital by Chlorine Dioxide / 环境与健康杂志

Objective To explore the concentration of required residual available chlorine dioxide(ClO 2 )and optimun contact time for ClO 2 disinfection in order to ensure the microbiological indexes of waste water of hospital disinfected by ClO 2 qualified.Meth ods The waste water samples collected from hospital,to which were aritificially added with predetermined con-centrations of bacteria,were disinfected by various concentrations of ClO 2 (2?4?6?8?10?12mg /L)with various contact time (5?10?30?60?90min).After disinfection,the concentration of residual ClO 2 and the contents of microorganism in waste water samples were determined.Re sults After30-min disinfection by10.0mg /L ClO 2 ,the waste water sample originally containing1.52?10 2 /L E.coli showed a bactericidal rate of99.99%and a concentration of residual ClO 2 at2.5mg /L.After10-min disin-fection by10.0mg /L ClO 2 ,the waste water samples originally containing1.12?10 10 /L Salmonella showed a bactericidal rate of100%and a concentration of residual ClO 2 at2mg /L.After5-min disinfection by10.0mg /L ClO 2 ,the waste water samples o-riginally containing M.tu berculosis at concentration of++++showed a negative result and a concentration of residual ClO 2 at3.5mg/L.Conclusion After the primary treatment,ClO 2 disinfection with contact time of30minutes and a residual concentration of ClO 2 at2.5mg /L could ensure the germicidal effect for E.coli,Salmonella and M.tu berculosis in waste water of hospital qualified.