Transformation mechanism of carbon tetrachloride and the associated micro-ecology in landfill cover, a typical functional layer zone / 生物工程学报

Landfill is one of the important sources of carbon tetrachloride (CT) pollution, and it is important to understand the degradation mechanism of CT in landfill cover for better control. In this study, a simulated landfill cover system was set up, and the biotransformation mechanism of CT and the associated micro-ecology were investigated. The results showed that three stable functional zones along the depth, i.e., aerobic zone (0-15 cm), anoxic zone (15-45 cm) and anaerobic zone (> 45 cm), were generated because of long-term biological oxidation in landfill cover. There were significant differences in redox condition and microbial community structure in each zone, which provided microbial resources and favorable conditions for CT degradation. The results of biodegradation indicated that dechlorination of CT produced chloroform (CF), dichloromethane (DCM) and Cl- in anaerobic and anoxic zones. The highest concentration of dechlorination products occurred at 30 cm, which were degraded rapidly in aerobic zone. In addition, CT degradation rate was 13.2-103.6 μg/(m2·d), which decreased with the increase of landfill gas flux. The analysis of diversity sequencing revealed that Mesorhizobium, Thiobacillus and Intrasporangium were potential CT-degraders in aerobic, anaerobic and anoxic zone, respectively. Moreover, six species of dechlorination bacteria and eighteen species of methanotrophs were also responsible for anaerobic transformation of CT and aerobic degradation of CF and DCM, respectively. Interestingly, anaerobic dechlorination and aerobic transformation occurred simultaneously in the anoxic zone in landfill cover. Furthermore, analysis of degradation mechanism suggested that generation of stable anaerobic-anoxic-aerobic zone by regulation was very important for the harmless removal of full halogenated hydrocarbon in vadose zone, and the increase of anoxic zone scale enhanced their removal. These results provide theoretical guidance for the removal of chlorinated pollutants in landfills.

Clinicopathological Studies on Rats Exposed to Municipal Landfill Gaseous and Particulate Emissions

The study assessed the Clinicopathological changes of Wistar rats exposed to municipal landfill gaseous particulate emissions. Four groups of Wistar rats were exposed to the different sites of landfill emission with use of filters for filtering landfill gaseous emission while the control group was not exposed. Performance of the animals was evaluated weekly, blood and lung, liver, kidney and heart tissues were taken for haematological and histopatholgical examinations. At the end of six weeks exposure, the peak weight was recorded as 108.96±0.45 of Group B as compared to 126.352±0.88 of the Control Group, as well as the decrease in the body weight of Group A-D compared to the Control Group. There was leucocytosis, lymphocytosis and neutrophilia in the rats that were exposed to landfill emission. There were pulmonary, hepatic, and renal lesions while the heart was spared. Changes were observed on the use of filters for filtering landfill gaseous emission. The 3M 6001 CN Gas Mask Carnister Cartridge which filters 50% of landfill emission together with black polythene nylon restricting external air into the filtered cage was not sufficient to reduce the effect of landfill gaseous emission at the end of the exposure period. The screening with PM2.5 material which filters 100% of PM2.5 emission was only able to screen PM2.5 emission but could not screen other landfill gaseous emission. This indicates that landfill gaseous emission is capable of inducing respiratory problems and tissue damage on dumpsite workers if there is sufficient and continuous exposure to landfill gaseous emissions. To prevent the hazard that may arose from dumpsite activities; gas nose mask respirator is recommended for an individual who works as scavengers and landfill workers before entering the dumpsite environment..

Treatment of livestock carcasses in soil using Corynebacterium glutamicum and lysosomal application to livestock burial

A method of rapidly decaying livestock carcasses is sought through Corine glutamicum, and furthermore, lysosomes are used to remove toxic microorganisms from livestock carcasses. The landfill was constructed on a laboratory scale. Optimized growth conditions of C. glutamicum that could quickly decay livestock carcasses were determined. Lysosomes were extracted from egg whites and used to treat contaminated soil to confirm their antimicrobial activities. Condition of C. glutamicum was activated, regardless both anaerobic and aerobic conditions, soil exists and, to be close to the optimum conditions as possible temperatures, moisture content was about 1/10 of the culture. Lysosomes were found to be effective in clearing soil contamination. C. glutamicum can accelerate the decay of livestock carcasses. A combination of C. glutamicum and lysomes could be used to treat soil contamination caused by decomposition of livestock.

Treatment of livestock carcasses in soil using Corynebacterium glutamicum and lysosomal application to livestock burial

A method of rapidly decaying livestock carcasses is sought through Corine glutamicum, and furthermore, lysosomes are used to remove toxic microorganisms from livestock carcasses. The landfill was constructed on a laboratory scale. Optimized growth conditions of C. glutamicum that could quickly decay livestock carcasses were determined. Lysosomes were extracted from egg whites and used to treat contaminated soil to confirm their antimicrobial activities. Condition of C. glutamicum was activated, regardless both anaerobic and aerobic conditions, soil exists and, to be close to the optimum conditions as possible temperatures, moisture content was about 1/10 of the culture. Lysosomes were found to be effective in clearing soil contamination. C. glutamicum can accelerate the decay of livestock carcasses. A combination of C. glutamicum and lysomes could be used to treat soil contamination caused by decomposition of livestock.

Feasibility Of Landfill Establishment In Khomeynishahr City Of Isfahan Using Gis, Mce And Boolean Logic

@#Land filling is the most common disposal method in most parts of the world and landfill site has always been the final destination in solid waste management hierarchy. Thus, the selection of landfill site is always an essential part in the management of solid waste. Selecting an appropriate site for landfill minimizes any unwarranted ecological and socio-economic effects. Hence, landfill site selection requires a detailed analysis of the area that must be able to meet the local authority requirement and criteria. The present study presents a feasibility assessment of landfill establishment for Khomeynishahr city in Isfahan, applying a multi criteria evaluation (MCE) method using GIS technique. Information layers related to topography, soil, water table, sensitive habitats, land use and geology maps were prepared and superposed using Boolean logic in GIS environment. Essential analysis and regulation, criteria and site selection assessment showed that because of many limitations khomeynishahr city doesn’t have adequate conditions for landfill site establishment. Khomeynishahr city has a dense population and limited area and is not suitable for landfill establishment. In this case consideration of adjacent cities and finding a common landfill site between two or more cities could be a viable solution of solving this problem.

Modificação do conhecimento sobre acidentes de trabalho entre escolares residentes de uma área impactada por aterro sanitário / Modification of knowledge on occupational accidents among schoolchildren who resided in a landfill impacted area

RESUMO: Introdução: A prevalência de acidentes de trabalho no Brasil é elevada, tendo impactos no sistema de saúde e na Previdência Social e requerem ações de prevenção, as quais devem ser iniciadas com estudantes da Educação Básica. Objetivo: Foi estimado o conhecimento sobre acidentes de trabalho, antes e depois de atividades de educação para a saúde, entre escolares que residem em área impactada por um aterro sanitário. Métodos: Foi realizado em 2013 um estudo transversal que incluiu a aplicação de um mesmo questionário entre alunos matriculados numa escola da rede municipal de Cuiabá-MT, Brasil, antes e depois de atividades de educação para a saúde voltadas para a definição dos acidentes de trabalho. Procedeu-se análise univariada de frequências absolutas e relativas e análise bivariada utilizando o Teste do χ2 e o Teste Exato de Fisher, com nível de 0,05 de significância e IC95%. Resultado: Verificou-se aumento estatisticamente significativo do conhecimento sobre acidente de trabalho de uma fase para outra do programa (p < 0,05). Conclusão: As atividades desenvolvidas evidenciaram a escola como espaço privilegiado para a valorização e a sistematização de saberes advindo da realidade dos escolares.

ABSTRACT: Introduction: The prevalence of occupational accidents is very high in Brazil, having impacts on the health system and social security. This requires prevention, which must start with students of the Basic Education. Objectives: The knowledge on this kind of accidents among children and adolescents studying in an area near a sanitary landfill was evaluated, before and after the development of activities on health education. Methods: A cross-sectional study was conducted in 2013 and included the application of the same questionnaire among students from a school in Cuiabá-MT, Brazil, before and after educational health activities related to the definition of occupational accidents. Univariate analyses of absolute and relative frequencies and bivariate analyses using the χ2 Test and Fisher's Exact Test were performed with a significance level of 0.05 and 95%CI. Results: There was a statistically significant increase of the knowledge on these types of accidents after the educational activities (p < 0.05). Conclusion: The activities carried out indicate that schools are important for the development and systematization of knowledge arising from reality.

Management of “SHARPS” Wastes in Manila Hospitals (Part 3) Off -Site Management of Hazardous Healthcare Wastes in Six Tertiary Hospitals in South Manila, Philippines

@#<p style="text-align: justify;"><strong>OBJECTIVE:</strong> The aim of this study was to determine if the collection, treatment and final disposal of hospital hazardous wastes conform to the rules and regulations and standards set by the Philippine Government and the World Health Organization (WHO). <br /><strong>METHODS:</strong> Three private and three government tertiary hospitals located in South Manila were randomly chosen and the companies that provides them with hospital waste disposal services were asked to participate in the study to validate their conformity to the national and international hazardous waste disposal standards. Validation was done through the use of observer checklists and photographs.<br /><strong>RESULTS:</strong> Results of the study showed that there were four companies who services 6 selected hospitals included in the study. All of these conformed to the standards of the World Health Organization, and to rules and regulations as set by the Philippine government. All of the companies conformed as to standards for Legal Permits, Off-site Transport, Personal Protective Devices and Off-Site Waste Disposal.<br /><strong>CONCLUSION:</strong> All of the companies servicing the 6 selected hospitals conformed to the standards set by WHO and the Philippine government.</p>

Mulheres catadoras de materiais recicláveis: condições de vida, trabalho e saúde / Mujeres seleccionadoras de materiales reciclables: condiciones de vida, trabajo y salud / Women waste pickers: living conditions, work, and health

RESUMO Objetivo Conhecer elementos relacionados às condições de vida, ao trabalho e à saúde de mulheres catadoras de materiais recicláveis, cooperativadas em um município do estado do Rio Grande do Sul, Brasil. Método Estudo qualitativo, exploratório-descritivo, com sete catadoras de uma cooperativa de reciclagem. A produção de dados incluiu observação participante, entrevistas semiestruturadas e grupo focal, de julho a agosto de 2013. Utilizou-se a análise de conteúdo. Resultados Emergiram as seguintes categorias temáticas: Trabalho feminino, informalidade e precariedade; Vivências de satisfação no trabalho; e Condições de trabalho e saúde: as experiências com acidentes, adoecimento e serviços de saúde. Conclusão Evidenciou-se a precariedade que caracteriza a atividade laboral das catadoras de materiais recicláveis, as quais estão expostas a riscos potenciais à saúde como sobrecarga de trabalho, acidentes, adoecimento e inseguridade social, bem como o papel da enfermagem no sentido de promover ações em prol da saúde e inclusão dessas trabalhadoras.

RESUMEN Objetivo Conocer los elementos relacionados con las condiciones de vida, trabajo y salud de mujeres recolectora de materiales reciclables, cooperativitas en una ciudad de Rio Grande do Sul, Brasil. Método Estudio cualitativo, exploratorio-descriptivo, con siete sujeto de una cooperativa de reciclaje.. La recolección de datos incluyó observación participante, entrevistas semiestructuradas y grupo focal, de julio a agosto de 2013. Para análisis, se utilizó el análisis de contenido. Resultados Surgieron las siguientes categorías temáticas: Trabajo femenino, informalidad y precariedad; Experiencias de satisfacción en el trabajo; y condiciones de trabajo y salud: las experiencias con accidentes, enfermedad y los servicios de salud. Conclusión Se mostró la precariedad que caracteriza la actividad laboral de los recolectores de materiales reciclables, quienes están expuestas a los riesgos potenciales para la salud, tales como la sobrecarga de trabajo, los accidentes, las enfermedades y la inseguridad social, así como el papel de la enfermería con el fin de promover acciones para la salud y la inclusión de estas trabajadoras.

ABSTRACT Objective To know the elements of work, health, and living conditions of women who pick recyclable waste and are members of a waste cooperative in a town of the state of Rio Grande do Sul, Brazil. Method This is a qualitative, exploratory and descriptive study with seven subjects. Data were collected through participative observation, semi structured interview, and a focus group from July to August of 2013. The data were subjected to content analysis. Results The following thematic categories emerged: Women's work, informality and precariousness; Experiences of job satisfaction; and Working conditions and health: experiences with accidents, illness and health services. Conclusion It was concluded that the women who collect recyclable material are exposed to precarious work conditions and potential health risks, such as work overload, accidents, illness, and social insecurity, and that nurses are responsible for promoting actions that ensure the health and inclusion of these workers.

Evaluation of phytotoxicity of municipal landfill leachate before and after biological treatment / Avaliação da fitotoxicidade de chorume de aterro sanitário antes e após tratamento biológico

In the present study, leachate toxicity of a municipal solid waste landfill located in the Sinos River Valley region (southern Brazil) was evaluated using plant bioassays. Leachate toxicity was assessed by analysis of seed germination and root elongation of lettuce (Lactuca sativa L.) and rocket plant (Eruca sativa Mill.) and root elongation of onions (Allium cepa L.). Bioassays were performed by exposing the seeds of L. sativa and E. sativa and the roots of A. cepa to raw leachate, treated leachate (biological treatment) and negative control (tap water). The levels of metals detected in both samples of leachate were low, and raw leachate showed high values for ammoniacal nitrogen and total Kjeldahl nitrogen. There is a reduction in the values of several physicochemical parameters, which demonstrates the efficiency of the treatment. Both L. sativa and A. cepashowed a phytotoxic response to landfill leachate, showing reduced root elongation. However, the responses of these two plant species were different. Root elongation was significantly lower in A. cepa exposed to treated leachate, when compared to negative control, but did not show any difference when compared to raw leachate. In L. sativa, seeds exposed to the raw leachate showed significant reduction in root elongation, when compared to treated leachate and negative control. Seed germination showed no difference across the treatments. The results of the study show that plant species respond differently and that municipal solid waste landfill leachate show phytotoxicity, even after biological treatment.

No presente trabalho, a toxicidade do lixiviado (chorume) de um aterro sanitário municipal, localizado na região do Vale do Rio dos Sinos, foi avaliada utilizando bioensaios em plantas. A toxicidade do chorume foi analisada pelo teste de germinação e crescimento radicular de alface (Lactuca sativa L.) e rúcula (Eruca sativa Mill.) e pelo teste de crescimento radicular em cebola (Allium cepa L.). Os bioensaios foram realizados com a exposição de sementes de L. sativa e E. sativa e raízes de A. cepa a amostras de chorume bruto, tratado por processo biológico e controle negativo (água de abastecimento público). Os níveis de metais detectados nas amostras de chorume foram baixos, e o chorume bruto apresentou valores elevados de nitrogênio amoniacal e nitrogênio Kjeldahl total. Ocorreu redução nos valores de vários parâmetros físico-químicos, demonstrando a eficiência do tratamento biológico. Os resultados indicam fitotoxicidade do chorume em L. sativa e A. cepa, evidenciada pela redução do crescimento radicular. Entretanto, as respostas destas duas espécies diferiram. O crescimento radicular foi significativamente inferior em A. cepa exposta ao chorume tratado quando comparado ao controle negativo, mas não apresentou diferença quando comparado ao chorume bruto. Em L. sativa, a exposição das sementes ao chorume bruto causou redução no crescimento radicular quando comparado com o chorume tratado e controle negativo. Não foram observadas diferenças entre os tratamentos para o parâmetro germinação de sementes. Os resultados deste trabalho indicam que as espécies de plantas estudadas são diferentes em suas respostas e que o chorume apresenta toxicidade, mesmo após o tratamento biológico.

Nanowastes treatment in environmental media

OBJECTIVES: This paper tried to review a recent research trend for the environmental exposure of engineered nanomaterials (ENMs) and its removal efficiency in the nanowaste treatment plants. METHODS: The studies on the predicted environmental concentrations (PEC) of ENMs obtained by exposure modeling and treatment (or removal) efficiency in nanowaste treatment facilities, such as wastewater treatment plant (WTP) and waste incineration plant (WIP) were investigated. The studies on the landfill of nanowastes also were investigated. RESULTS: The Swiss Federal Laboratories for Materials Science and Technology group has led the way in developing methods for estimating ENM production and emissions. The PEC values are available for surface water, wastewater treatment plant effluents, biosolids, sediments, soils, and air. Based on the PEC modeling, the major routes for the environmental exposure of the ENMs were found as WTP effluents/sludge. The ENMs entered in the WTP were 90-99% removed and accumulated in the activated sludge and sludge cake. Additionally, the waste ash released from the WIP contain ENMs. Ultimately, landfills are the likely final destination of the disposed sludge or discarded ENMs products. CONCLUSIONS: Although the removal efficiency of the ENMs using nanowaste treatment facilities is acceptable, the ENMs were accumulated on the sludge and then finally moved to the landfill. Therefore, the monitoring for the ENMs in the environment where the WTP effluent is discharged or biomass disposed is required to increase our knowledge on the fate and transport of the ENMs and to prevent the unintentional exposure (release) in the environment.

Avaliação de impactos do efluente do tratamento combinado de lixiviado de aterro de resíduos sólidos urbanos e esgoto doméstico sobre a biota aquática / Assessment of impacts of combined treatment of solid urban waste landfill leachate and sewage on aquatic biota

Foi monitorado o impacto do tratamento combinado de lixiviado e esgoto doméstico de uma estação de tratamento operando em escala piloto por processo de lodos ativados, sobre peixes do gênero Tilapia: Biomarcadores de toxicidade (concentração de metalotioneínas, atividade da acetilcolinesterase, metábolitos de HPA e presença de micronúcleos) foram utilizados na avaliação dos riscos de danos aos organismos aquáticos devido à interação com poluentes contidos nos efluentes pós-tratamento. A concentração de metalotioneínas não apresentou variação significativa entre os grupos expostos e de controle. A atividade da enzima acetilcolinesterase foi inibida em apenas um dos grupos expostos, indicando possível presença de agentes inibidores no efluente tratado. A avaliação dos metabólitos dos HPA naftaleno, pireno, benzo(a)pireno e 1-hidroxipireno sinalizou a provável presença desses compostos em ao menos um dos afluentes do tratamento combinado. As frequências de micronúcleos e outras anormalidade nucleares eritrocitárias também apontam para maior incidência de danos genotóxicos em células dos organismos expostos do que nos controles. O uso de biomarcadores mostrou-se importante para possibilitar uma avaliação de danos subletais presentes em organismos expostos à fonte de poluição estudada.

The impact on tilapia fish of combined treatment of landfill leachate and domestic sewage was monitored in a waste treatment plant that operated on a pilot scale using the activated sludge process. Biomarkers of sub-lethal toxicity were used to indicate the possibility of damage to organisms due to interaction with pollutants. The concentration of metallothioneins did not indicate the increased presence of metals in fish exposed than in control groups. Acetylcholinesterase enzyme activity was inhibited in only one of the exposed groups, indicating the possible presence of organophosphate and/or carbamate pesticides in treated effluent. The PAHs used as biomarkers (naphthalene, pyrene, benzo(a)pyrene and 1-hydroxypyrene) indicated that exposed fish had a greater absorption of PAHs than control groups of fish, indicating the likely presence of these compounds in at least one of the combined treatment effluents. The frequencies of micronuclei and other erythrocytic nuclear abnormalities also indicate greater genotoxic damage in cells of organisms exposed than in control groups. The use of biomarkers proved to be important to permit an evaluation of sub-lethal damage present in organisms exposed to the pollution source studied.

Ameliorating topsoil conditions by biosolid application for a waste landfill landscape

Sanitary landfills, created for the disposal of solid waste, usually are developed into parks after they are closed. However, soil amelioration with organic matter is usually needed to restore fertility and promote revegetation. Sewage sludge creates a massive waste disposal problem. The use of composted sewage sludge [biosolid] as a soil conditioner might restore the soil fertility at landfill sites and simultaneously alleviate the need for sewage sludge disposal. We applied biosolid to waste landfill soil and evaluated its effects on soil properties and tree growth in a field experiment. Biosolid improved soil characteristics including moisture, organic matter, and nitrogen content and also increased tree height and diameter at breast height. Physiological measures, such as chlorophyll content and photosynthetic rate, showed positive responses in trees grown in biosolid treatments. Heavy metal concentrations in soil and tree leaves after applying compost did not differ from concentrations measured at control sites. Therefore, we conclude that the use of biosolid in waste landfills would be an efficient, environmentally beneficial, and cost-effective method to restore the conditions of landfill soil for plants

Comparison the efficacy of fenton and "nZVI + H[2]O[2]" processes in municipal solid waste landfill leachate treatment [case study: Hamadan landfill leachate]

Leachate contains large amounts of pollutants, including organic and inorganic materials as well as the types of pathogens. This study was performed with the aim of determining the efficiency of Fenton and" nZVI[nanoparticles of zero valent iron] + H[2]O[2]" processes for reducing chemical oxygen demand [COD], 5-day biological oxygen demand [BOD[5]], total solids [TS]and color of Hamadan city landfill leachate. Experiments were performed in batch reactor and main affected factors; pH, reaction time, concentration of iron and H[2]O[2] were investigated. Also the efficiency of processes was analyzed using One-Way ANOVA statistical test and SPSS-13 software. The highest removal efficiencies obtained with "nZVI + H[2]O[2]" process [48.67%, 52%, 10.44% and 53% for COD, BOD[5], TS and color, respectively in 2.5 g/L iron nanoparticles concentration, 29137 mg/L H[2]O[2], pH = 2.5 and 60 min reaction time]. Based on the results, the nZVI + H[2]O[2] process can be applied as Hamadan city landfill leachate treatment to correct the BOD[5]/COD ratio to increase the biodegrability of this type of wastewater

Hospital waste management; practices in different hospitals of Distt. Peshawar

Hospital waste is a special type of waste which carries high potential of infection and injury. This study was conducted to examine Medical Waste Management Practices in different hospitals of Peshawar. Simple observational, cross-sectional study was conducted with a case study approach. Aug-Sep 2011, with selection of 15 hospitals. The data was collected through a pre-designed questionnaire with a checklist. The study showed that 80% of the hospital personnel knew hospital waste and its management. There was waste management plan present in 30% of hospitals. Although hospitals did not quantified waste amounts but on average the amount of waste generated daily was 0.5-1 kg/bed/day. Segregation into risk and non risk waste was done in 93.3% of hospitals. For non risk waste, disposal through Municipal Corporation was conducted in 86.67% of the hospitals, while in 13.3%, it was burnt. For risk waste, either it was buried or burnt. Proper incineration was carried out in only 33.3% of the hospitals. Discussion: Hospital waste generation, segregation, collection, transportation and disposal practices were not in accordance with standard guidelines. The average waste generation in most of the hospitals was almost equivalent to other under developed countries but less than that of developed countries. The hospital waste in the majority of hospitals of Peshawar was mismanaged. No proper hospital waste management plan existed except at few hospitals

Health Assessment for Glass Fibre Landfill at Gozan-dong, Inchon / 예방의학회지

In September 1994, residents of Gozan-dong, Incheon City, made a petition to the government about their health problems which might be caused by previous glass fibre landfill nearby "H" company. In February 1995, at regular academic meeting of occupational and environmental medicine, a research team of "D" University presented that they had found glass fibres in groundwater of the area through their survey. They were suspicious of probable association between ingestion of groundwater contaminated with glass fibres and skin tumors among residents. A joint research team was formed and carried out the survey of environment concerning groundwater and its glass fibre existence, and health assessment of residents in the area and industrial workers of "H" company during May to November, 1995. Analysis of groundwater flow system indicates that the flow lines from the glass fibre landfill pass through or terminate at the 6 houses around the landfill. This means that the groundwater of the 6 houses around the glass fibre landfill could be affected by some possible contaminants from the landfill, but the groundwater quality of the other houses was irrelevant to the landfill. The qualitative and quatitative analyses for glass fibres in 54 groundwater samples including those from the nearby 6 houses, were carried out using SEM equipped with EDS, resulting in no evidence for the presence of glass fibres in the waters. Major precipitates, formed in waters while boiling, were identified as calcium carbonates, in particulary, aragonites in needle form. The results of health assessments of 889 residents in Gozan-dong, participated in this study, showed statistically significant differences in past medical histories of skin tumor and respiratory disease between the exposed group (31 persons who inhabited in 6 houses around the landfill) and the control group, but no significant differences in past medical histories of other diseases, such as cancer mortality, current gastroscopic findings, current skin diseases and respiratory diseases, etc. Also, we could not prove any glass fibres in excised specimens of 9 skin tumors in both groups and there were no health problems possibly associated with glass fibres in employees of the "H" company. After all, we could not authenticate the association, raised by prior investigators, between groundwater streams, assumedly contaminated with glass fibres or not, and specific disease morbidities or common disease/symptom prevalences. That is, we could not find any glass fibres in groundwater as the only exposure factor of this study hypothesis, and there were not enough certain evidences such as increasing disease prevalences, for examples, skin, respiratory and gastrointestinal diseases etc, possibly related to glass fibre exposure, in exposed group. As a matter of course, the conditions for confirming causal association, for example, strength of the association, consistency of the association, specificity of the association, temporality of the association and dose-response relationship etc, have not been satisfied. In conclusion, we were not able to certify the hypothesis that contamination of groundwater with glass fibres might cause any hazardous health effects in human who used it for drinking.