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| 2. |
- Jarnheimer, Per-åke, et al.
(författare)
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Fluoroquinolone Antibiotics in a Hospital Sewage Line; Occurrence, Distribution and Impact on Bacterial Resistance
- 2004
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Ingår i: Scandinavian Journal of Infectious Diseases. - : Informa UK Limited. - 0036-5548 .- 1651-1980. ; 36:10, s. 752-5
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Tidskriftsartikel (refereegranskat)abstract
- In hospital sewage lines, human faecal bacteria are exposed to antibiotics, posing a risk for selection of antibiotic resistant microorganisms. We constructed a system for continuous sampling in a hospital sewage line that allowed us to study longitudinal establishment of bacteria, concentrations of antibiotics, and selection of bacterial resistance in waste water, sediment and biofilm. The focus in this study was on fluoroquinolones, a widely used group of antibiotics with increasing resistance problems. We found low levels of ciprofloxacin and ofloxacin in waste water but high concentrations in sediment. Despite the high levels of fluoroquinolones bound to sediment, we did not find any development of resistance against fluoroquinolones in Enterobacteriacae spp. and faecal enterococci isolated from sediment.
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| 3. |
- Ottoson, Jakob, et al.
(författare)
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Faecal contamination of greywater and associated microbial risks
- 2003
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Ingår i: Water Research. - 0043-1354 .- 1879-2448. ; 37:3, s. 645-655
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Tidskriftsartikel (refereegranskat)abstract
- The faecal contamination of greywater in a local treatment system at Vibyasen, north of Stockholm, Sweden was quantified using faecal indicator bacteria and chemical biomarkers. Bacterial indicator densities overestimated the faecal load by 100-1000-fold when compared to chemical biomarkers. Based on measured levels of coprostanol, the faecal load was estimated to be 0.04 g person(-1) day(-1). Prevalence of pathogens in the population and the faccal load were used to form the basis of a screening-level quantitative microbial risk assessment (QMRA) that was undertaken for rotavirus, Salmonella typhimurium, Campylobacter jejuni, Giardia lamblia and Cryptosporidium parvum. The different exposure scenarios simulated-direct contact, irrigation of sport fields and groundwater recharge-gave unacceptably high rotavirus risks (0.04
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| 4. |
- Westrell, Therese, et al.
(författare)
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A theoretical approach to assess microbial risks due to failures in drinking water systems
- 2003
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Ingår i: International Journal of Environmental Health Research. - : Informa UK Limited. - 0960-3123 .- 1369-1619. ; 13:2, s. 181-197
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Tidskriftsartikel (refereegranskat)abstract
- A failure in treatment or in the distribution network of a surface water-works could have serious consequences due to the variable raw water quality in combination with an extended distribution. The aim of this study was to examine the theoretical impact of incidents in the drinking water system on the annual risk of infection in a population served by a large water treatment plant in Sweden. Reported incidents in the system were examined and a microbial risk assessment that included three pathogens, Cryptosporidium parvum, rotavirus and Campylobacter jejuni, was performed. The main risk incidents in water treatment were associated with sub-optimal particle removal or disinfection malfunction. Incidents in the distribution network included cross-connections and microbial pollution of reservoirs and local networks. The majority of the annual infections were likely to be due to pathogens passing treatment during normal operation and not due to failures, thus adding to the endemic rate. Among the model organisms, rotavirus caused the largest number of infections. Decentralised water treatment with membranes was also considered in which failures upstream fine-pored membranes would have little impact as long as the membranes were kept intact.
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| 5. |
- Westrell, Therese
(författare)
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Microbial risk assessment and its implications for risk management in urban water systems
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Infectious disease can be transmitted via various environmental pathways, many of which are incorporated into our water and wastewater systems. Quantitative microbial risk assessment (QMRA) can be a valuable tool in identifying hazard exposure pathways and estimating their associated health impacts. QMRA can be applied to establish standards and guidelines and has been adopted by the World Health Organisation for the management of risks from water-related infectious diseases. This thesis aims at presenting a holistic approach for the assessment of microbial health risks in urban water and wastewater systems. The procedure of QMRA is presented, together with the data collected for the case studies, and the results are discussed in a risk management framework.Decentralised drinking water treatment with membranes was shown to be competitive with centralised conventional treatment regarding environmental impacts and health. To attain sufficient die-off of pathogens in order to reduce risks to acceptable levels, facilities that permit the long-term storage of locally collected faeces are required. Issues of operation and mangement are likely to determine the health risks in decentralised systems. While failures in distribution are more likely to result in detectable waterborne disease outbreaks, the number of people at risk of becoming infected with pathogens passing normal treatment, calculated on a yearly basis, can be larger. Site-specific pathogen monitoring of source waters was identified as an important factor for the accurate estimation of risk. Noroviruses, an emerging waterborne pathogen, were shown to have fluctuating concentrations in surface water, with significant peaks during the wintertime. Time series analysis has potential as an early warning system if complemented by regular monitoring to discriminate peaks from random fluctuations. Groups already sensitive to infection, i.e. the elderly, the sick and children, were shown to consume higher volumes of cold tap water than the rest of the population, which may call for special atention in the risk management of drinking water systems. Microbial health risks associated with the handling and reuse of wastewater and sludge were shown to be successfully addressed within the management system Hazard Analysis and Critical Control Points (HACCP). Most exposure points identified could be controlled through easy measures.
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