<p>To assess the performance of both treatment on reducing the infection risk, this study developed the Indoor Air Quality (IAQ) model that simulates the dynamics of airborne infective SARS-CoV-2 in a 500 m3 with or without mechanical ventilation and UV system. Then this model was linked to a quantitative microbial risk assessment (QMRA) to allow for estimation of the risk of disease transmission for a given treatment condition.</p>

The impact of climate change on drinking water is one of the fastest-growing challenges within the water sector. Microbial contamination of drinking water has been a serious issue for decades now and will exacerbate in the coming future. Until recently the impact of climate change was only evaluated qualitatively and there has been a growing need for a quantitative risk assessment. This review covers different ways of incorporating the effects of climate change into the risk assessment framework. A comprehensive search through two databases was conducted resulting in 596 citations being screened for relevance, of which 23 were confirmed as relevant. Ten risk assessment frameworks and 3 tools obtained from this review were used for the comparative study with the Swedish QMRA tool. Data from multiple frameworks and tools were extracted to identify potential additions required for the improvement of the Swedish tool. Two approaches, i.e. data-driven and process-based, were identified and the foundation for a new framework was set up. Two pathways to implement these approaches were laid out with the first being the addition of new modules to the existing tool and the second being the use of hydrodynamic and water quality models to predict the impact of climate change on infection risks.

Drinking water is produced from raw water and is either from groundwater or surface water. This thesis aims to find out if the cleaning process of raw water is sufficiently effective. This is important because consumers are otherwise at risk of waterborne infection caused by pathogens. There are three groups of pathogens; bacteria, virus and parasite. These have different characteristics which mean that they require different water treatment to be separated. In addition to normal operation, a number of scenarios were examined. This is to investigate how water treatment would do if they became a reality. The thesis has examined Borg´s waterworks operated by Norrköping Vatten AB. It was defined to cover the distance from water source to the consumer. In the work, the model Quantitative Microbial Risk Assessment (QMRA) was used to perform risk analysis by simulating the normal operation and different scenarios of the water purification process. Thus, knowledge can be obtained about the effectiveness of separation by bacteria, viruses and parasites. However, the QMRA-model is considered to contain some flaws and for that reason the Norwegian model called Good Disinfection Practice (GDP) was also used. GDP is a theoretical model which is based on formulas and tables. The model takes into account the raw water quality and also provides deductions for various measures that the water plant possesses to ensure a good supply of water. The results obtained with both models were similar and showed that the water treatment is sufficient for the bacteria, but not viruses and parasites. Both models were considered to be reliable but viruses and parasites are very difficult to analyze, which has resulted in uncertain literature values and hence in the results. The result also showed that neither viruses nor parasites exceeded the limit by so much that more hygienic barriers to the reduction of them are necessary. The conclusion which may be drawn from the fact that no parasites have been detected in the raw water is that the water treatment still might be sufficient. To determine the effects that an exclusion of various barriers may give, the normal operation was simulated and a purification step at a time was excluded. The result showed that the purification steps which are most important to maintain the treatment process are chemical precipitation followed by rapid filtration, slow filtration and disinfection with chlorine. If any of these cleaning steps were to fail, this introduces a large increase in the risk of waterborne disease. The results showed that the chemical precipitation step gave the greatest separation effect on the virus but also on the parasites. However, the slow filtration gave the largest separation of the parasites. Free chlorine had the greatest effect on bacteria. The investigated scenarios were assumed to be wastewater discharges, sewage discharges in relation to flood the nearby pastures, and sewage overflows due to heavy rainfall. The results of the simulated scenarios were the same when it was only bacteria that in all cases produced a result within the limits of the daily infection probability. Both viruses and parasites exceeded both values. However, there were few studies on these and thus literature values needed to be implemented in the QMRA-model. Hence, the uncertainty of the results was great. The QMRA-model also contained deficiencies in the simulation of the discharge of effluents, where the amount of virus was about 1000-10000 times too much. If this problem as well as more specific data for the investigated area, and more Swedish studies were available, a more credible simulation of the scenarios could be implemented.

The effectiveness of Boil Water Advisories (BWAs) as a public health risk management tool is increasingly being questioned. Newfoundland and Labrador's zero-risk policy for issuing BWAs on public drinking water systems has resulted in over 210 active BWAs annually, the majority classified as long-term BWAs. BWAs are more likely to occur on small systems, in communities with low economic capacity, and in communities without a certified operator. No relationship was found relating confirmed cases of water-related illness to BWAs. Quantifiable health risk associated with BWAs was evaluated using Quantitative Microbial Risk Assessment (QMRA). Data on source water pathogen concentrations and epidemiological data was used to evaluate and calibrate the QMRA Model. The study demonstrated the application of QMRA in determining whether health risk warranted issuing a BWA. Eleven recommendations were made on how the province could adopt QMRA in establishing an alternative drinking water risk management and advisory framework.

Less than 10% of the world’s domestic wastewater is disinfected prior to discharge into surface waters; therefore, human exposure to diverse wastewater-related pathogens results in millions of cases of illness each year. Among the enteric pathogens, viruses represent an important group of emerging pathogens and are frequently the cause of food- and water-borne outbreaks of illness. Although the World Health Organization and many government agencies mandate the use of bacterial indicators to identify poor microbial water quality, it is well known that these indicators poorly correlate with fecal pollution contamination events and risk of disease. The field of public health-related environmental microbiology has made significant advances over the last twenty years; however, there is still a need for improved methods to identify poor microbial water quality and manage health risks associated with water-related activities (e.g., recreation, shellfish harvesting, irrigation). Furthermore, it is imperative to effectively detect fecal pollution in the environment as well as determine the extent of pathogen removal during (waste)water treatment to meet the Sustainable Development Goals associated with water and food security as well as the water reuse recommendations by the U.S. National Research Council. This dissertation directly addressed the need to identify an improved viral indicator by exploring the application of pepper mild mottle virus (PMMoV), a virus of dietary origin that is extremely abundant in human feces, as a surrogate for enteric viruses in diverse settings and contexts. Using a reverse transcription quantitative polymerase chain reaction (RT-qPCR) method, PMMoV was compared with other indicators, index surrogates, and reference pathogens for assessing surface water quality in a developed country (Appendix A) and developing country context (Appendix B and C). In addition, the applicability of PMMoV as a (waste)water treatment process indicator was demonstrated in natural treatment systems in developing countries (Appendix C and D) and artificial treatment systems (Appendix E). In all settings, PMMoV always co-occurred with at least one reference pathogen, index organism, and/or indicator; additionally, PMMoV was detected more frequently and in higher concentrations than other reference pathogens and indicators. Three investigations also associated PMMoV detection with predicted human health risks greater than the health benchmark for recreation and water reuse activities (Appendix A, C, and D). Additionally, PMMoV facilitated an improved understanding of virus-particle interactions in wastewater treatment pond systems (Appendix D) and allowed for an improved understanding of virus removal with respect to riverbank filtration systems and wastewater reuse in agriculture (Appendix C). PMMoV was established as a valuable component of the microbial source tracking toolbox in Costa Rica (Appendix B) and appeared to be useful in Bolivia (Appendix C). Finally, a paradigm shift in (waste)water management is occurring, in which routine monitoring is being replaced by a more holistic approach that includes sanitary surveys, targeted water quality monitoring, and exploratory quantitative microbial risk assessment. To support and complement this paradigm shift, field-based, laboratory-free methods are needed to identify and/or infer the presence of enteric viruses (Appendix F). Collectively, all the investigations presented here confirm the use of PMMoV as a surrogate for enteric viruses; however, its utility depends on the context and research question.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第19372号 / 工博第4117号 / 新制||工||1635(附属図書館) / 32386 / 新制||工||1635 / 京都大学大学院工学研究科都市環境工学専攻 / (主査)教授 伊藤 禎彦, 教授 田中 宏明, 教授 米田 稔 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

Yes / This paper presents a study to assess the roof-harvested rainwater (RHRW) in the Ikorodu area of Lagos state, Nigeria, and recommends guidance to minimise the health risk for its households. The types, design and use of rainwater harvesting systems have been evaluated in the study area to inspect the human risk of exposure to Escherichia coli (E. coli). To achieve these objectives, a detailed survey involving 125 households has been conducted which showed that 25% of them drink RHRW. Quantitative microbial risk assessment (QMRA) analysis has been used to quantify the risk of exposure to harmful E. coli from RHRW utilised as potable water, based on the ingestion of 2 L of rainwater per day per capita. Results have revealed that the maximum E. coli exposure risk from the consumption of RHRW, without application of any household water treatment technique (HHTTs) and with application of alum only, were 100 and 96 respectively, for the estimated number of infection risk per 10,000 exposed households per year. This estimation has been done based on 7% of E. coli as viable and harmful. Conclusively, it is necessary that a form of disinfectant be applied to the RHRW before use.

In low-resource contexts, household-level point-of-use water treatment (POUWT) techniques are the final, and sometimes only, barrier against waterborne illnesses, and in these and other water-related applications, health risks can be quantified using one of two methods. Firstly, Escherichia coli (or other indicator organism) counts can be used to monitor water and determine adherence to a health-based limit (i.e. compliance monitoring). Secondly, E. coli can be used to conduct a quantitative microbial risk assessment (QMRA), indicating the level of protection conferred by a given POUWT device by spiking test water with E. coli to ascertain a reduction efficacy relative to that target organism, a process referred to as challenge testing, which is typically carried out in a laboratory context. Although both methods are well established, both have scope for improvement for effective field application in low-resource contexts. Regarding compliance monitoring, I assessed the performance of a new low-cost field kit for E. coli enumeration, which was designed by others. I also assessed the feasibility of re-using some disposable materials, in terms of sterility and mechanical wear. The use of the new low-cost field kit was successful during the fieldwork campaign; however, re-using disposable materials introduced a relatively high occurrence of false positive results during E. coli enumeration. Use of the new low-cost field kit can reduce financial barriers, thus enabling greater water quality testing coverage. Regarding challenge testing, the aim of this study was to adapt current protocols to assess the household performance (as opposed to laboratory performance) of POUWT techniques. I developed a conceptual framework to conduct Field Challenge Tests (FCT’s) on POUWT techniques, using a probiotic health supplement containing E. coli as the challenge organism. I successfully carried out a FCT in Malawi with limited resources, verifying FCT viability. Applications of such FCT’s include quality control practices for manufactured devices, guiding QMRA and recommendations by public health organizations regarding POU device selection, and assessing the impact of user training programmes regarding POUWT techniques. / Graduate

Dados mundiais apontam haver uma associação entre o aumento do comércio de vegetais minimamente processados prontos para o consumo (VPC) e o aumento da ocorrência de surtos de enfermidades transmitidas por alimentos. Durante o processamento industrial de VPC, a desinfecção é a principal etapa de inativação de micro-organismos patogênicos presentes, mas nessa etapa também pode ocorrer contaminação cruzada, com transferência de contaminantes de produtos contaminados para não-contaminados. Neste trabalho, foram coletadas informações sobre as práticas empregadas na etapa de desinfecção em dez importantes indústrias produtoras de VPC no Estado de São Paulo, avaliando-se, em seguida, a influência dessas práticas na qualidade microbiológica dos produtos e na inativação de Salmonella Typhimurium, bem como na ocorrência de contaminação cruzada por este patógeno. Um modelo de avaliação quantitativa de risco microbiológico foi elaborado para estimar o impacto da contaminação cruzada durante a etapa de desinfecção no risco de infecção por Salmonella devido ao consumo de VPC. Observou-se que, em todas as indústrias visitadas, a desinfecção dos vegetais era feita com produtos à base de cloro em concentrações de 50 a 240 mg/L, que resultava em redução de até 1,2 log na carga microbiana dos vegetais que entravam na linha de processamento. Ao avaliar a influência das características da água de processamento (pH, temperatura, concentração de matéria orgânica e concentração de dicloroisocianurato de sódio) e do tempo de contato entre a água clorada e os vegetais na redução de Salmonella, observou-se que a concentração do produto à base de cloro foi o parâmetro que apresentou maior influência (p<0.05). Concentrações de dicloroisocianurato de sódio acima de 10 mg/L foram necessárias para controle da contaminação cruzada durante a etapa de lavagem. O modelo de avaliação de risco construído indicou quantitativamente haver uma relação entre a concentração de dicloroisocianurato de sódio na água de desinfecção e o risco de ocorrência de surtos causados por Salmonella em VPC. Cenários simulando uso de dicloroisocianurato de sódio em concentrações abaixo de 5 mg/L indicaram que mais de 96% dos casos preditos de infecção por Salmonella poderiam ser atribuídos à ocorrência de contaminação cruzada, enquanto que em cenários com concentrações acima de 50 mg/L, casos de infecção devidos à contaminação cruzada não foram preditos. Estes resultados mostram que o controle da qualidade da água e o monitoramento da concentração de sanitizante na etapa de desinfecção são essenciais para evitar a ocorrência de contaminação cruzada e garantir a produção de VPC seguros para o consumo. / Surveillance data in several countries show an association between consumption of minimally processed ready-to-eat (RTE) vegetables and increased occurrence of foodborne diseases outbreaks. During RTE vegetables processing, washing-disinfection is the main step aiming to ensure inactivation of pathogenic microorganisms, but also is the step in which cross-contamination may occur, with transfer of contaminants from contaminated to non-contaminated products. In this study, we collected information on the practices employed during the washing-disinfection step in ten RTE vegetables processing plants located in the State of Sao Paulo, Brazil, and evaluated the influence of these washing practices on the microbial quality of the products and inactivation of Salmonella Typhimurium, as well as on the occurrence of cross-contamination by this pathogen. A quantitative microbial risk assessment model was built in order to estimate the impact of cross-contamination during the washing step on the risk of infection by Salmonella due to the consumption of RTE vegetables. In all visited processing plants, the disinfection step was done using chlorine-based products, in concentrations ranging from 50 to 240 mg/L, achieving a reduction of up to 1.2 log in the microbial load of vegetables entering the processing line. When the influence of washing water parameters (pH, temperature, organic load and sodium dichloroisocyanurate concentration) and time of contact between chlorinated water and vegetables on reduction of Salmonella were evaluated, sodium dichloroisocyanurate concentration influenced the most (p<0.05). Concentrations above 10 mg/L were necessary for avoiding cross-contamination during washing step. The risk assessment model indicated quantitatively a relationship between sodium dichloroisocyanurate concentration and the risk of illness caused by Salmonella in RTE vegetables. When simulation was done with less than 5 mg/L of sodium dichloroisocyanurate, most (>96%) of the illnesses arose from cross-contamination. However, when the concentration was 50 mg/L or higher, no illnesses arising from cross-contamination were predicted. These results show that controlling the quality of the water and monitoring the concentration of the sanitizer in the disinfection step are essential to avoid occurrence of cross contamination and ensure production of RTE vegetables that are safe for consumption.

O uso das águas costeiras para fins recreacionais está associado com benefícios à saúde e bem-estar, todavia eventuais impactos negativos podem diminuir estes benefícios. Esses usos variam de acordo com o tipo de atividade desenvolvida, sendo que a recreação de contato primário requer contato direto e prolongado com a água, durante a qual pode ocorrer ingestão acidental. A Resolução CONAMA nº 274/2000 dispõe sobre os critérios de balneabilidade e reza que as condições da qualidade das águas recreacionais devem ser avaliadas através de indicadores microbiológicos de contaminação fecal, e ainda recomenda que seja realizada pesquisa de organismos patogênicos em praias sistematicamente impróprias. Dada a escassez de dados da ocorrência de patógenos em águas costeiras, no período de 2010 a 2012, a CETESB realizou o Estudo de microrganismos patogênicos nas praias do Litoral Paulista pesquisando enterovírus, adenovírus, vírus da hepatite A, Cryptosporidium sp e Giardia sp, no intuito de preencher esta lacuna e gerar dados primários. Assim, o objetivo deste trabalho foi estimar a probabilidade de infecção por Cryptosporidium sp e Giardia sp após exposição a águas recreacionais costeiras usando como ferramenta a Avaliação Quantitativa de Risco Microbiológico (AQRM), como também o risco de doença. As concentrações de (oo)cistos nas águas das praias são oriundas dos relatórios de Qualidade das Praias Litorâneas no Estado de São Paulo da CETESB dos anos de 2011 e 2012. Nesse período foram analisadas 203 amostras coletadas de 12 praias na 1ª fase e de cinco praias na 2ª fase para a pesquisa de ocorrência de (oo)cistos. As amostras de água foram coletadas na isóbata de um metro, com frequência mensal. Giardia sp foi o microrganismo mais frequente, presente em 43 por cento das amostras e Cryptosporidium sp em 13 por cento . O cenário de exposição considerou tipos de atividade, tipos de usuários (crianças, adultos e esportistas), concentração de (oo)cistos, volume de ingestão, duração e frequência da exposição. A probabilidade de infecção foi maior em praias com mais amostras positivas para oocistos e cistos, no grupo dos esportistas e para Giardia sp. Em alguns casos os valores de risco de doença ultrapassaram o risco tolerável pela U.S. EPA (2012) de 3,6 por cento casos de gastroenterite, assim como ultrapassaram os resultados de incidência acumulada encontradas por LAMPARELLI et al. (2015). Os resultados apontaram a necessidade de melhoria nos sistemas de tratamento de efluentes no Litoral Paulista. A AQRM é uma ferramenta capaz de estimar a probabilidade de infecção no cenário das águas recreacionais e pode auxiliar no gerenciamento dos riscos. / The use of coastal water for recreational purposes has been associated with benefits to health and well-being; however some negative impacts can diminish such benefits. The usages can vary according to the type of activity but the primary contact demands physical contact resulting in a high probability in accidental ingestion of water. Brazilian legislation for coastal recreational waters CONAMA 274/2000 establishes criteria for fecal indicator bacteria and furthermore recommends investigation of pathogenic organisms for beaches which classification is systematically as improper. Given the scarcity of data referring to pathogenic presence in beaches´ waters, CETESB carried out a study, in 2010 and 2012, for quantifying enterovirus, adenovirus, hepatitis A virus, Cryptosporidium sp and Giardia sp in coastal waters of São Paulo state in order to obtain data about their occurrence of these pathogens in coastal waters. The objective of this study was to estimate the annual risk of infection and disease for Giardia sp and Cryptosporidium sp by ingestion of water during primary contact recreation using QMRA approach. Concentrations of both parasites were taken from the annual report entitled Quality of coastal beaches in São Paulo state by CETESB (2011 and 2012). In these years were analyzed 203 samples of water for quantifying (oo)cysts of Giardia and Cryptosporidium from 12 beaches in the first year and five beaches in the second year of research. The samples were collected at one meter isobaths, with monthly frequency. Giardia was the most frequent parasite present in 43 per cent of samples and Cryptosporidium sp in 13 per cent . Exposure scenario was built considering types of activity, beach goers (children, adults and athletes), concentration of parasites, ingestion rate, duration and frequency of exposure. The probability of annual infection was higher in beaches in which there were more positive results for parasites for athletes and for Giardia infection. The tolerable risk for gastroenteritis by USEPA, which is 3.6 per cent , was overpassed in some cases. Though the results found in this study overpassed the cumulative incidence reported by LAMPARELLI et al. (2015). The results indicate the need for improvements in wastewater treatment systems in the coastal area of São Paulo. As QMRA is a tool capable in estimating the probability of infection it can help to highlight crucial issues in risk management.