Substance flow analysis as a tool for mitigating the impact of pharmaceuticals on the aquatic system

Retention of Ciprofloxacin and Carbamazepine from Aqueous Solutions Using Chitosan-Based Cryostructured Composites

Water pollution is becoming a great concern at the global level due to highly polluted effluents, which are charged year by year with increasing amounts of organic residues, dyes, pharmaceuticals and heavy metals. For some of these pollutants, the industrial treatment of wastewater is still relevant. Yet, in some cases, such as pharmaceuticals, specific treatment schemes are urgently required. Therefore, the present study describes the synthesis and evaluation of promising cryostructured composite adsorbents based on chitosan containing native minerals and two types of reinforcement materials (functionalized kaolin and synthetic silicate microparticles). The targeted pharmaceuticals refer to the ciprofloxacin (CIP) antibiotic and the carbamazepine (CBZ) drug, for which the current water treatment process seem to be less efficient, making them appear in exceedingly high concentrations, even in tap water. The study reveals first the progress made for improving the mechanical stability and resilience to water disintegration, as a function of pH, of chitosan-based cryostructures. Further on, a retention study shows that both pharmaceuticals are retained with high efficiency (up to 85.94% CIP and 86.38% CBZ) from diluted aqueous solutions.

Modelling local nanobiomaterial release and concentration hotspots in the environment

Nanobiomaterials (NBMs) are a special category of nanomaterials used in medicine. As applications of NBMs are very similar to pharmaceuticals, their environmental release patterns are likely similar as well. Different pharmaceuticals were detected in surface waters all over the world. Consequently, there exists a need to identify possible NBM exposure routes into the environment. As the application of many NBMs is only carried out at specific locations (hospitals), average predicted environmental concentrations (PECs) may not accurately represent their release to the environment. We estimated the local release of poly(lactic-co-glycolic acid) (PLGA), which is investigated for their use in drug delivery, to Swiss surface waters by using population data as well as type, size and location of hospitals as proxies. The total mean consumption of PGLA in Switzerland using an explorative full-market penetration scenario was calculated to be 770 kg/year. 105 hospitals were considered, which were connected to wastewater treatment plants and the receiving water body using graphic information system (GIS) modelling. The water body dataset contained 20,167 river segments and 210 lake polygons. Using the discharge of the river, we were able to calculate the PECs in different river segments. While we calculated high PLGA releases of 2.24 and 2.03 kg/year in large cities such as Geneva or Zurich, the resulting local PECs of 220 and 660 pg/l, respectively, were low due to the high river discharge (330 and 97 m³/s). High PLGA concentrations (up to 7,900 pg/l) on the other hand were calculated around smaller cities with local hospitals but also smaller receiving rivers (between 0.7 and 1.9 m³/s). Therefore, we conclude that population density does not accurately predict local concentration hotspots of NBMs, such as PLGA, that are administered in a hospital context. In addition, even at the locations with the highest predicted PLGA concentrations, the expected risk is low.

Role of Models in the Decision-Making Process in Integrated Urban Water Management: A Review

Managing urban water systems in which stormwater, wastewater, and drinking water sectors affect each other is a difficult task that requires the right modeling tools for decision making. Integrated urban water management models (IUWMs) are tools that allow decision makers to demonstrate the effectiveness of various management, operational and design strategies. Although models are useful tools, the wide range of available models with many different capabilities make it challenging for the users to select an appropriate model for their specific objectives. In this review we investigated the capabilities of popular models in IUWM. We developed a comprehensive list of indicators to compare the capabilities of the models. We also analyzed the application of these models in a comparative way and evaluated their input requirements. Finally, we provided a procedure to select the appropriate model in the management environment based on the user’s needs. In summary, the results show that most of the models’ applications are focused on supply and demand, wastewater management, and stormwater management. Very few models consider social factors and policy aspects in IUWM. While each model has its own advantages, we found some of them, such as MIKE Urban, Hydro Planner, and Aqua Cycle, to be more comprehensive. Nevertheless, there are still gaps in the models in areas such as water-energy nexus, evaluating ecosystem services, including socioeconomic factors and sustainability analysis.

A review of combined sewer overflows as a source of wastewater-derived emerging contaminants in the environment and their management

Emerging contaminants such as pharmaceuticals, illicit drugs and personal care products can be released to the environment in untreated wastewater/stormwater mixtures following storm events. The frequency and intensity of combined sewer overflows (CSOs) has increased in some areas due to increasing urbanisation and climate change. Therefore, this review provides an up-to-date overview on CSOs as an environmental source of emerging contaminants. Other than compounds with high removal, those chiral species subject to enantioselective changes (i.e. degradation or inversion) during wastewater treatment can be effective markers of CSO discharge in the environment. A proposed framework for the selection of emerging contaminants as markers of CSOs is outlined. Studies have demonstrated that CSOs can be the main source of emerging contaminants with high removal efficiency during wastewater treatment (e.g. > 90%). However, the impact of CSOs on the environment is location specific and requires decision-making on their appropriate management at catchment level. This process would be aided by further studies on CSOs which incorporate the monitoring of emerging contaminants and their effects in the environment with those more routinely monitored pollutants (e.g. pathogens and priority substances). Mitigation and treatment strategies for emerging contaminants in CSOs are also discussed.

Most relevant sources and emission pathways of pollution for selected pharmaceuticals in a catchment area based on substance flow analysis

The release of micropollutants in surface water depends on different sources and on different pathways. Through substance flow analysis, this study estimates the annual load of two pharmaceuticals (carbamazepine and sulfamethoxazole) in a catchment area, due to different emission pathways: wastewater treatment plant effluent, combined sewer overflows, and runoff from sludge and manure amended soil. It emerged that wastewater treatment plant effluent is the main emission pathway for carbamazepine (98.5% referring to the total released annual load) and land runoff (98%) for sulfamethoxazole. The study also investigates the parameters (including manure disposed on the land, removal efficiency and combined sewer overflow flowrate) which mostly influence the results, and those which are affected by higher uncertainty. The most uncertain parameters are those determining the fate of pharmaceuticals once in soil and surface water. The study concludes with a comparison between the predicted concentrations in different points of the receiving water body of the two key compounds, modeled with substance flow analysis, and those directly measured in a dedicated sampling campaign. The main discrepancies were found for sulfamethoxazole. Future research focusing on monitoring campaigns under different weather conditions and in different environmental compartments (soil and water) will certainly provide new insights in this kind of study.

Probabilistic modelling of nanobiomaterial release from medical applications into the environment

Nanobiomaterials (NBMs) are currently being tested in numerous biomedical applications, and their use is expected to grow rapidly in the near future. Many different types of nanomaterials are employed for a wide variety of different applications. Silver nanoparticles (nano-Ag) have been investigated for their antibacterial, antifungal, and osteoinductive properties to be used in catheters, wound healing, dental applications, and bone healing. Polymeric nanoparticles such as poly(lactic-co-glycolic acid) (PLGA) are mainly studied for their ability to deliver cancer drugs as the body metabolizes them into simple compounds. However, most of these applications are still in the development stage and unavailable on the market, meaning that information on possible consumption, material flows, and concentrations in the environment is lacking. We thus modeled a realistic scenario involving several nano-Ag and PLGA applications which are already in use or likely to reach the market soon. We assumed their full market penetration in Europe in order to explore the prospective flows of NBMs and their environmental concentrations. The potential flows of three application-specific composite materials were also examined for one precise application each: Fe₃O₄PEG-PLGA used in drug delivery, MgHA-collagen used for bone tissue engineering, and PLLA-Ag applied in wound healing. Mean annual consumption in Europe, considering all realistic and probable applications of the respective NBMs, was estimated to be 5,650 kg of nano-Ag and 48,000 kg of PLGA. Mean annual consumption of the three application-specific materials under the full market penetration scenario was estimated to be 4,000 kg of Fe₃O₄PEG-PLGA, 58 kg of MgHA-collagen, and 24,300 kg of PLLA-Ag. A probabilistic material-flow model was used to quantify flows of the NBMs studied from production, through use, and on to end-of-life in the environment. The highest possible worst-case predicted environmental concentration (wc-PEC) were found to occur in sewage sludge, with 0.2 µg/kg of nano-Ag, 400 µg/kg of PLGA, 33 µg/kg of Fe₃O₄PEG-PLGA, 0.007 µg/kg of MgHA-collagen, and 2.9 µg/kg of PLLA-Ag. PLGA exhibited the highest concentration in all environmental compartments except natural and urban soil, where nano-Ag showed the highest concentration. The results showed that the distribution of NBMs into different environmental and technical compartments is strongly dependent on their type of application.

Towards control strategies for microplastics in urban water

Microplastics (plastic particles < 5 mm) is a pollution of growing concern. Microplastic pollution is a complex issue that requires systematic attempts to provide an overview and avoid management solutions that have marginal effects or only move the pollution problem. Substance flow analysis (SFA) has been proposed as a useful tool to receive such an overview and has been put forward as valuable for substance management. However, as the research on microplastics has only emerged recently, detailed and reliable SFAs are difficult to perform. In this study, we use three SFA studies for three pollutants (cadmium, copper and pharmaceuticals) to compare flows and strategies to control the flows. This in order to seek guidance for microplastic management and evaluate potential strategies for controlling microplastics. The analysis shows that there has been rigorous control on different levels to abate pollution from cadmium, copper and pharmaceuticals, but where in the system the major control measures have been carried out differ. For microplastics, there are many potential solutions, both in terms of preventive actions and treatment depending on the type of source. When forming management plans for microplastics, the responsibility for each measure and the impact on the whole urban system should be taken into consideration as well as which receiving compartments are particularly valuable and should be avoided.

Risk-management tool for environmental prioritization of pharmaceuticals based on emissions from hospitals

Over the past decade, the health care sector has become increasingly aware of the impact of pharmaceutical emissions to the environment. Yet, it remains unclear which compounds are the most relevant to address and at what point emission control is most effective. This study presents a modelling framework to prioritize pharmaceuticals based on their relative risks for aquatic organisms, using purchase and prescription data from hospitals. The framework consists of an emission prediction module and a risk prioritization module. The emission prediction module accounts for three different routes of intake (oral, intravenous, rectal), for non-patient consumption, and for delayed athome excretion due to relatively long half-lives or prescription durations of selected pharmaceuticals. We showcase the modelling framework with 16 pharmaceuticals administered at two Dutch academic hospitals. Predictions were validated with experimental data from passive sampling in the sewer system. With the exception of metformin, all predictions were within a factor of 10 from measurements. The risk prioritization module ranks each pharmaceutical based on its predicted relative risk for aquatic organisms. The resulting prioritization suggests that emission mitigation strategies should mainly focus on antibiotics and non-steroidal anti-inflammatory drugs (NSAIDs).

Modeling pharmaceutical emissions and their toxicity-related effects in life cycle assessment (LCA): A review

Over the last few decades, worldwide detection of active pharmaceutical ingredients (APIs) in aquatic environments and the associated toxicological effects on wildlife and human health have become a matter of public and scientific debate. While life cycle assessment (LCA) and life cycle impact assessment (LCIA) models are increasingly used to assess the potential eco- and human-toxicological effects of chemical emissions, few studies have looked into the issue of modeling pharmaceutical emissions specifically and their toxicity-related effects in an LCA context. This paper reviews the state of the art to inventory and characterize API emissions in LCA with the goal to identify relevant gaps and challenges. A search for 208 environmentally relevant APIs in 2 life cycle inventory (LCI) databases revealed a meager representation of this group of chemicals. Similarly, the LCIA model USEtox was found to include characterization factors (CFs) for less than 60 APIs. First approaches to model API emissions in LCA were identified on the basis of an examination of 40 LCA case studies in the pharmaceutical sector and in the field of wastewater treatment. Moreover, CFs for 79 additional APIs, expressing their ecotoxicity and/or human toxicity potential, were gathered from literature. An analysis of the variability of API-CFs in different LCIA models showed a variation of about 2-3 orders of magnitude. Based on the review results, 3 main gaps in the modeling and characterization of API emissions in an LCA context were identified: (1) incomplete modeling of API flows and API emissions along the life cycle of human pharmaceuticals, especially during their use and end-of-life phase, (2) limited API coverage in existing LCIA toxicity models, and (3) missing pharma-specific impact pathways (e.g., endocrine disruption and antibiotic resistance) in existing LCIA models. Recommendations to tackle these gaps are provided, and priority action steps are discussed. Integr Environ Assess Manag 2019;15:6-18. © 2018 SETAC.

Ecotoxicity and antibiotic resistance of a mixture of hospital and urban sewage in a wastewater treatment plant

Hospital and urban effluents are a source of diverse pollutants such as organic compounds, heavy metals, detergents, disinfectants, pharmaceuticals, and microorganisms resistant to antibiotics. Usually, these two types of effluent are mixed in the sewage network, but a pilot site in France now allows studying them separately or mixed to understand more about their characteristics and the phenomena that occur following their mixing. In this study, their ecotoxicity (Daphnia magna mobility, Pseudokirchneriella subcapitata growth, Brachionus calyciflorus reproduction, and SOS Chromotest) and antibiotic resistance (integron quantification) were assessed during mixing and treatment steps. The main results of this study are (i) the ecotoxicity and antibiotic resistance potentials of hospital wastewater are higher than in urban wastewater and (ii) mixing two different effluents does not lead to global synergistic or antagonistic effects on ecotoxicity and antibiotic resistance potential. The global additivity effect observed in this case must be confirmed by other studies on hospital and urban effluents on other sites to improve knowledge relating to this source of pollution and its management.

Estimation of chemical emissions from down-the-drain consumer products using consumer survey data at a country and wastewater treatment plant level

Deriving reliable estimates of chemical emissions to the environment is a key challenge for impact and risk assessment methods and typically the associated uncertainty is not characterised. We have developed an approach to spatially quantify annual chemical emission loads to the aquatic environment together with their associated uncertainty using consumer survey data and publicly accessible and non-confidential data sources. The approach is applicable for chemicals widely used across a product sector. Product usage data from consumer survey studies in France, the Netherlands, South Korea and the USA were combined with information on typical product formulations, wastewater removal rates, and the spatial distribution of populations and wastewater treatment plants (WWTPs) in the four countries. Results are presented for three chemicals common to three types of personal care products (shampoo, conditioner, and bodywash) at WWTP and national levels. Uncertainty in WWTP-specific emission estimates was characterised with a 95% confidence interval and ranged up to a factor of 4.8 around the mean, mainly due to uncertainty associated with removal efficiency. Estimates of whole country product usage were comparable to total market estimates derived from sectorial market sales data with differences ranging from a factor 0.8 (for the Netherlands) to 5 (for the USA). The proposed approach is suitable where measured data on chemical emissions is missing and is applicable for use in risk assessments and chemical footprinting methods when applied to specific product categories.

Contributions of combined sewer overflows and treated effluents to the bacterial load released into a coastal area

The impact of combined sewer overflow (CSO) on the receiving water body is an issue of increasing concern, as it may lead to restrictions in the use and destination of the receiving body, such as bathing or recreational area closures, fish and shellfish consumption restrictions, and contamination of drinking water resources. Recent investigations have mainly referred to the occurrence and loads of suspended solids, organic compounds and, in some cases, micropollutants. Attempts have been made to find correlations between the discharged load and the size and characteristics of the catchment area, climate conditions, rainfall duration and intensity. This study refers to a touristic coastal area in the north-east of Italy, which is characterized by a combined sewer network including 5 CSO outfalls which, in the case of heavy rain events, directly discharge the exceeding water flow rate into channels which, after a short distance, reach the Adriatic Sea. The study analyzed: i) rainfall events during the summer period in 2014 which led to overflow in the different outfalls, ii) the inter- and intra-event variability with regard to E. coli, Enterococci and conductivity, and iii) the hydraulic and pollutant (E. coli and Enterococci) loads discharged by the local wastewater treatment plant and by all the CSO outfalls. Finally, it estimated the contribution of each source to the released hydraulic and pollutant loads into the receiving water body. Moreover, it was also found that the modest water volume discharged by all CSO outfalls (only 8% of the total volume discharged by the area) contains >90% of the microbial load.

Model-based screening for critical wet-weather discharges related to micropollutants from urban areas

Wet-weather discharges contribute to anthropogenic micropollutant loads entering the aquatic environment. Thousands of wet-weather discharges exist in Swiss sewer systems, and we do not have the capacity to monitor them all. We consequently propose a model-based approach designed to identify critical discharge points in order to support effective monitoring. We applied a dynamic substance flow model to four substances representing different entry routes: indoor (Triclosan, Mecoprop, Copper) as well as rainfall-mobilized (Glyphosate, Mecoprop, Copper) inputs. The accumulation on different urban land-use surfaces in dry weather and subsequent substance-specific wash-off is taken into account. For evaluation, we use a conservative screening approach to detect critical discharge points. This approach considers only local dilution generated onsite from natural, unpolluted areas, i.e. excluding upstream dilution. Despite our conservative assumptions, we find that the environmental quality standards for Glyphosate and Mecoprop are not exceeded during any 10-min time interval over a representative one-year simulation period for all 2500 Swiss municipalities. In contrast, the environmental quality standard is exceeded during at least 20% of the discharge time at 83% of all modelled discharge points for Copper and at 71% for Triclosan. For Copper, this corresponds to a total median duration of approximately 19 days per year. For Triclosan, discharged only via combined sewer overflows, this means a median duration of approximately 10 days per year. In general, stormwater outlets contribute more to the calculated effect than combined sewer overflows for rainfall-mobilized substances. We further evaluate the Urban Index (A_{urban,impervious}/A_natural) as a proxy for critical discharge points: catchments where Triclosan and Copper exceed the corresponding environmental quality standard often have an Urban Index >0.03. A dynamic substance flow analysis allows us to identify the most critical discharge points to be prioritized for more detailed analyses and monitoring. This forms a basis for the efficient mitigation of pollution.

Triclosan: A review on systematic risk assessment and control from the perspective of substance flow analysis

Triclosan (TCS) is a broad spectrum antibacterial agent mainly used in Pharmaceutical and Personal Care Products. Its increasing use over recent decades have raised its concentration in the environment, with commonly detectable levels found along the food web-from aquatic organisms to humans in the ecosystem. To date, there is shortage of information on how to investigate TCS's systematic risk on exposed organisms including humans, due to the paucity of systematic information on TCS flows in the anthroposphere. Therefore, a more holistic approach to mass flow balancing is required, such that the systematic risk of TCS in all environmental matrices are evaluated. From the perspective of Substance Flow Analysis (SFA), this review critically summarizes the current state of knowledge on TCS production, consumption, discharge, occurrence in built and natural environments, its exposure and metabolism in humans, and also the negative effects of TCS on biota and humans. Recent risk concerns have mainly focused on TCS removal efficiencies and metabolism, but less attention is given to the effect of mass flows from source to fate during risk exposure. However, available data for TCS SFA is limited but SFA can derive logical systematic information from limited data currently available for systematic risk assessment and reduction, based on mass flow analysis. In other words, SFA tool can be used to develop a comprehensive flow chart and indicator system for the risk assessment and reduction of TCS flows in the anthroposphere, thereby bridging knowledge gaps to streamline uncertainties related to policy-making on exposure pathways within TCS flow-lines. In the final analysis, specifics on systematic TCS risk assessment via SFA, and areas of improvement on human adaptation to risks posed by emerging contaminants are identified and directions for future research are suggested.

Management of pharmaceutical substances in the environment: Lithuanian case study

Investigation on the sources, discharges and related risks for the environment of the pharmaceutical substance (PhS) diclofenac (DCF) was performed in Lithuania, a country of the Baltic Sea region, for the first time. The investigation only refers to DCF as a PhS for human use; emissions from animal husbandry were not considered. In the first stage of the research, the main sources and pathways of DCF via substance flow analysis were identified within the country. During the second stage, DCF flows along the wastewater treatment plants (WWTPs) in two different cities were measured in order to assess the current levels of pharmaceutical residues in the environment. Furthermore, environmental risk assessment was carried out by taking into account the parameters of consumption data and elimination rate in WWTPs. Then, the assessment of different technical and managerial removal approaches was accomplished in an environmental management model of wastewater containing PhS, based on the framework of environmental systems theory.

Identification of phototransformation products of the antiepileptic drug gabapentin: Biodegradability and initial assessment of toxicity

The anticonvulsant drug Gabapentin (GAB) is used for the treatment of various diseases (e.g. epilepsy, bipolar disorder, neuropathic pain) and is being consumed in high amounts. As GAB is not metabolized and shows a weak elimination in sewage treatment plants (STPs), it has been detected in surface water and even in raw potable water. Moreover, the confirmed teratogenic effects of GAB indicate the need for further investigations regarding options for the elimination of GAB in the water cycle. Little is known about the behavior of GAB during treatment with UV light, which is normally used for the disinfection of potable water and discussed for advanced wastewater treatment. In this study, GAB was exposed to polychromatic UV irradiation at different initial concentrations in aqueous solution. Afterwards the structures of the resulting phototransformation products (PTPs) were identified and elucidated by means of high-resolution mass spectrometry. GAB and photolytic mixtures were submitted to the Closed Bottle Test (CBT; OECD 301 D) to assess biodegradability. Furthermore, the toxicity of GAB and its photolytic mixtures was initially addressed on screening level using a modified luminescent bacteria test (LBT) and the umu-test (ISO/FDIS 13829). Environmentally realistic concentrations of GAB were disclosed by predicting STP influent concentrations (24.3 and 23.2 μg L(-1)). GAB with initial concentration of 100 mg L(-1) was eliminated by 80% after 128 min of direct UV irradiation, but just 9% of non-purgeable organic carbon (NPOC) was removed indicating the formation of dead-end transformation products (TPs). Structures of different PTPs were elucidated and several identical PTPs could also be identified at lower initial treatment concentrations (20 mg L(-1), 5 mg L(-1), 1 mg L(-1) and 0.1 mg L(-1)). GAB was classified as not readily biodegradable. Moreover, photo treatment did not result in better biodegradable PTPs. With increasing UV treatment duration, photolytic mixtures of GAB showed an increased inhibition of both, the bacterial luminescence emission as well as the growth in the modified LBT. In the umu-test no significant induction of the umuC gene as an indicator of genotoxicity was observed. Our results show that UV irradiation of GAB containing water would lead to the formation of recalcitrant PTPs. Considering that GAB was found in raw drinking water, the formation of toxic PTPs during drinking water treatment with UV light might be possible. Therefore, further studies should be conducted regarding the fate and effects on human health and the environment of GAB and the PTPs identified within this study.

Prioritization methodology for the monitoring of active pharmaceutical ingredients in hospital effluents

The important number of active pharmaceutical ingredients (API) available on the market along with their potential adverse effects in the aquatic ecosystems, lead to the development of prioritization methods, which allow choosing priority molecules to monitor based on a set of selected criteria. Due to the large volumes of API used in hospitals, an increasing attention has been recently paid to their effluents as a source of environmental pollution. Based on the consumption data of a Swiss university hospital, about hundred of API has been prioritized following an OPBT approach (Occurrence, Persistence, Bioaccumulation and Toxicity). In addition, an Environmental Risk Assessment (ERA) allowed prioritizing API based on predicted concentrations and environmental toxicity data found in the literature for 71 compounds. Both prioritization approaches were compared. OPBT prioritization results highlight the high concern of some non steroidal anti-inflammatory drugs and antiviral drugs, whereas antibiotics are revealed by ERA as potentially problematic to the aquatic ecosystems. Nevertheless, according to the predicted risk quotient, only the hospital fraction of ciprofloxacin represents a risk to the aquatic organisms. Some compounds were highlighted as high-priority with both methods: ibuprofen, trimethoprim, sulfamethoxazole, ritonavir, gabapentin, amoxicillin, ciprofloxacin, raltegravir, propofol, etc. Analyzing consumption data and building prioritization lists helped choosing about 15 API to be monitored in hospital wastewaters. The API ranking approach adopted in this study can be easily transposed to any other hospitals, which have the will to look at the contamination of their effluents.

Substance flow analysis and assessment of environmental exposure potential for triclosan in mainland China

Triclosan (TCS) is a widely-used antimicrobial agent in many consumer products around the world, and China is a major producer and consumer of TCS. In this study substance flow analysis (SFA) was used to construct a static model of anthropogenic TCS metabolism in China in 2008. The systematic SFA results were used to determine possible exposure pathways and trends in environmental exposure potential through different pathways. TCS discharged in wastewater mainly flowed into surface water sediment, ocean, and soil, where it accumulates in aquatic and agricultural products that may pose a higher risk to human health than brief exposure during consumption. Only 22% of TCS discharged was removed in the built environment with the remainder discharged into the natural environment, indicating that anthropogenic TCS metabolism in China is unsustainable. Per capita TCS consumption increased 209% from 2003 to 2012, resulting in increased discharge and accumulation in the environment. If current trends continue, it will increase to 713 mg capita(-1) yr(-1) in 2015 and 957 mg capita(-1) yr(-1) in 2020. Accordingly, annual environmental exposure potential will increase from 388 mg capita(-1) in 2008 to 557 mg capita(-1) in 2015 and 747 mg capita(-1) in 2020, indicating an increasing trend of exposure to environmental TCS. Results of Pearson correlation analysis suggested that feasible countermeasures to reduce environmental exposure potential for triclosan would include encouraging the development of small cities, raising awareness of health risks, nurturing environmentally-friendly consumer values, and improving the environmental performance of TCS-containing products.

A framework for the assessment of the environmental risk posed by pharmaceuticals originating from hospital effluents

The consumption of pharmaceuticals is increasing in both hospitals and households. After administration, many compounds enter the water cycle as parent compounds or their metabolites via excretion. Conventional municipal wastewater treatment plants are unable to efficiently remove all the different compounds found in sewage and, consequently, treated effluents are one of the main sources of persistent micropollutants in the environment. Hospital patients are administered relatively high quantities of drugs and therefore hospital wastewaters can consistently contribute to treatment plant influent loads, with the magnitude of environmental risk posed by pharmaceuticals originating from hospital effluents largely unknown. This study has therefore developed a framework to enable authorities responsible for hospital management and environmental health to evaluate such risk, considering site-specific information such as the contribution of human population and hospital sizes, wastewater treatment removal efficiency, and potential dilution in the receiving water body. The framework was applied to three case studies, that are representative of frequent situations in many countries, and findings demonstrated that the degree of risk posed by any compound was site-specific and depended on a combination of several factors: compound concentration and toxicity, compound removal efficiency in the wastewater treatment plant and dilution factor. Ofloxacin, 17α-ethinylestradiol, erythromycin and sulfamethoxazole were identified as compounds of concern and might require management in order to reduce risk.

Industrial metabolism of chlorine: a case study of a chlor-alkali industrial chain

Substance flow analysis (SFA) is applied to a case study of chlorine metabolism in a chlor-alkali industrial chain. A chain-level SFA model is constructed, and eight indices are proposed to analyze and evaluate the metabolic status of elemental chlorine. The primary objectives of this study are to identify low-efficiency links in production processes and to find ways to improve the operational performance of the industrial chain. Five-year in-depth data collection and analysis revealed that system production efficiency and source efficiency continued increasing since 2008, i.e., when the chain was first formed, at average annual growth rates of 21.01 % and 1.01 %, respectively. In 2011, 64.15 % of the total chlorine input was transformed into final products. That is, as high as 98.50 % of the chlorine inputs were utilized when other by-products were counted. Chlorine loss occurred mostly in the form of chloride ions in wastewater, and the system loss rate was 0.54 %. The metabolic efficiency of chlorine in this case was high, and the chain system had minimal impact on the environment. However, from the perspectives of processing depth and economic output, the case study of a chlor-alkali industrial chain still requires expansion.

Comparison of measured and predicted concentrations of selected pharmaceuticals in wastewater and surface water: a case study of a catchment area in the Po Valley (Italy)

The aim of this study is to compare measured and predicted concentrations of 11 antibiotics and the antiepileptic carbamazepine in wastewater and surface water and to discuss the accuracy and usefulness of applied predictive models in assessing their concentrations. The occurrence (exposure assessment) of the target compounds was monitored in the influent and effluent of a large municipal wastewater treatment plant, and in its receiving water body, situated in the Po Valley, Italy. Information on the consumption and sales of pharmaceuticals in Italy, along with data related to their excretion and removal during wastewater treatment, were used to predict the concentrations of the selected pharmaceuticals for the studied site. The measured and predicted concentrations were compared for all three sampling points, and according to a criterion available in literature and already adopted in similar studies, the prediction was considered "acceptable" when the ratio of predicted and measured concentrations was between 0.5 and 2. The results show that the concentrations were accurately predicted for ciprofloxacin in wastewaters, and for azithromycin, trimethoprim and carbamazepine in surface water. For all the other compounds and sampling points, the difference between the measured and the predicted concentrations was very high. Possible reasons for these discrepancies are discussed and the main potential factors that influence both measured and predicted concentrations are identified by means of an assessment of the uncertainties in the measured values and sensitivity of all the parameters required for predicting concentration ones. The potential factors are sampling mode for measured values and dilution factor, removal and excretion for predicted ones.