Astewater based on monthly sales data and the PEC model. Second, the fraction of antibiotics originating from hospitals in the total load found in wastewater was examined, again based on monthly consumption. The study considered nine substances ?azithromycin, ciprofloxacin, clarithromycin, clindamycin, metronidazole, norfloxacin, ofloxacin, sulfamethoxazole and trimethoprim ?using data for the city of Lausanne, Switzerland.VS-6063 Materials and Methods The WTP BasinThe study was conducted on the main WTP catchment of Lausanne, Switzerland. This WTP serves 2009000 residents, and is located at Vidy Bay, on the shore of Lake Geneva. The annual total wastewater volume PF-04554878 supplier treated is approximately 40|106 m3. The monthly water volume received at the WTP varies seasonally, as can be seen in Figure 1, which illustrates the dynamics of the monthly dry weather water volume at the Vidy Bay WTP inlet.Antibiotics Origin in WastewaterFigure 1. Monthly variations of dry weather flow at the Vidy Bay WTP inlet. Flow is normalized to the annual mean flow, which is 18|106 m3. The monthly baseflow fluctuates between +40/225 of the mean. doi:10.1371/journal.pone.0053592.gFigure 3. 25331948 Annual antibiotics sales estimated for the city of Lausanne. Blue: ambulatory sales, red: total sales. From one year to the next, the contribution of hospitals to the total load of antibiotics consumed varies little. Likewise, ambulatory sales show little variation. doi:10.1371/journal.pone.0053592.gThese monthly dry weather wastewater data were provided by Lausanne public authorities [28]. A seasonal trend can be observed with higher volumes in summer than in winter. Similar behaviour in WTP dry weather monthly flow volumes was observed in other studies [29,30]. In our approach, we considered only hospitals or clinics performing acute somatic treatments, as such establishments dispense antibiotic prescriptions. Ten hospitals were identified,for a total of 1600 beds. Their spatial distribution on the WTP basin is illustrated in Figure 2.Data SourceThe study is based on data from ambulatory (pharmacies) sales and hospital dispensaries. These data are considered as accurate measures of consumption. Antibiotics are prescription drugs, and are pathology-specific. Thus, the quantities prescribed should match their consumption, and sales should match the amountFigure 2. Schematic view of the Vidy Bay WTP basin considered in this study. The main pipes of the collection system are illustrated with bold lines. Hospitals and clinics for acute somatic treatment are located using grey pentagons. The total number of hospital beds in the basin is about 1600, which corresponds to a total of approximately 8 beds per 1000 inhabitant. doi:10.1371/journal.pone.0053592.gAntibiotics Origin in WastewaterTable 1. Description of the antibiotics sales datasets.Data AmbulatorySource OFACPeriod 2006?Frequency monthlyPopulation concerned Canton of VaudData processing Considered number of affiliated pharmacies To downscale to the Lausanne population Data were upscaled to the Lausanne hospital and bed countHospitalCHUV2006?monthlyCHUV pharmacyAmbulatory data sales were provided by OFAC for the Canton de Vaud. These data were downscaled to the Lausanne population based on pharmacy density. Hospital data were extrapolated based on that provided by the CHUV considering the total number of hospital beds in Lausanne. doi:10.1371/journal.pone.0053592.tprescribed. For antibiotics, this connection is supported by the high patien.Astewater based on monthly sales data and the PEC model. Second, the fraction of antibiotics originating from hospitals in the total load found in wastewater was examined, again based on monthly consumption. The study considered nine substances ?azithromycin, ciprofloxacin, clarithromycin, clindamycin, metronidazole, norfloxacin, ofloxacin, sulfamethoxazole and trimethoprim ?using data for the city of Lausanne, Switzerland.Materials and Methods The WTP BasinThe study was conducted on the main WTP catchment of Lausanne, Switzerland. This WTP serves 2009000 residents, and is located at Vidy Bay, on the shore of Lake Geneva. The annual total wastewater volume treated is approximately 40|106 m3. The monthly water volume received at the WTP varies seasonally, as can be seen in Figure 1, which illustrates the dynamics of the monthly dry weather water volume at the Vidy Bay WTP inlet.Antibiotics Origin in WastewaterFigure 1. Monthly variations of dry weather flow at the Vidy Bay WTP inlet. Flow is normalized to the annual mean flow, which is 18|106 m3. The monthly baseflow fluctuates between +40/225 of the mean. doi:10.1371/journal.pone.0053592.gFigure 3. 25331948 Annual antibiotics sales estimated for the city of Lausanne. Blue: ambulatory sales, red: total sales. From one year to the next, the contribution of hospitals to the total load of antibiotics consumed varies little. Likewise, ambulatory sales show little variation. doi:10.1371/journal.pone.0053592.gThese monthly dry weather wastewater data were provided by Lausanne public authorities [28]. A seasonal trend can be observed with higher volumes in summer than in winter. Similar behaviour in WTP dry weather monthly flow volumes was observed in other studies [29,30]. In our approach, we considered only hospitals or clinics performing acute somatic treatments, as such establishments dispense antibiotic prescriptions. Ten hospitals were identified,for a total of 1600 beds. Their spatial distribution on the WTP basin is illustrated in Figure 2.Data SourceThe study is based on data from ambulatory (pharmacies) sales and hospital dispensaries. These data are considered as accurate measures of consumption. Antibiotics are prescription drugs, and are pathology-specific. Thus, the quantities prescribed should match their consumption, and sales should match the amountFigure 2. Schematic view of the Vidy Bay WTP basin considered in this study. The main pipes of the collection system are illustrated with bold lines. Hospitals and clinics for acute somatic treatment are located using grey pentagons. The total number of hospital beds in the basin is about 1600, which corresponds to a total of approximately 8 beds per 1000 inhabitant. doi:10.1371/journal.pone.0053592.gAntibiotics Origin in WastewaterTable 1. Description of the antibiotics sales datasets.Data AmbulatorySource OFACPeriod 2006?Frequency monthlyPopulation concerned Canton of VaudData processing Considered number of affiliated pharmacies To downscale to the Lausanne population Data were upscaled to the Lausanne hospital and bed countHospitalCHUV2006?monthlyCHUV pharmacyAmbulatory data sales were provided by OFAC for the Canton de Vaud. These data were downscaled to the Lausanne population based on pharmacy density. Hospital data were extrapolated based on that provided by the CHUV considering the total number of hospital beds in Lausanne. doi:10.1371/journal.pone.0053592.tprescribed. For antibiotics, this connection is supported by the high patien.
