Multiple-criteria decision analysis reveals high stakeholder preference to remove pharmaceuticals from hospital wastewater.

Point-source measures have been suggested to decrease pharmaceuticals in water bodies. We analyzed 68 and 50 alternatives, respectively, for a typical Swiss general and psychiatric hospital to decrease pharmaceutical discharge. Technical alternatives included reverse osmosis, ozonation, and activated carbon; organizational alternatives included urine separation. To handle this complex decision, we used Multiple-Criteria Decision Analysis (MCDA) and combined expert predictions (e.g., costs, pharmaceutical mass flows, ecotoxicological risk, pathogen removal) with subjective preference-valuations from 26 stakeholders (authorities, hospital-internal actors, experts). The general hospital contributed ca. 38% to the total pharmaceutical load at the wastewater treatment plant, the psychiatry contributed 5%. For the general hospital, alternatives removing all pharmaceuticals (especially reverse osmosis, or vacuum-toilets and incineration), performed systematically better than the status quo or urine separation, despite higher costs. They now require closer scrutiny. To remove X-ray contrast agents, introducing roadbags is promising. For the psychiatry with a lower pharmaceutical load, costs were more critical. Stakeholder feedback concerning MCDA was very positive, especially because the results were robust across different stakeholder-types. Our MCDA results provide insight into an important water protection issue: implementing measures to decrease pharmaceuticals will likely meet acceptance. Hospital point-sources merit consideration if the trade-off between costs and pharmaceutical removal is reasonable.

Environmental toxicology and risk assessment of pharmaceuticals from hospital wastewater.

In this paper, we evaluated the ecotoxicological potential of the 100 pharmaceuticals expected to occur in highest quantities in the wastewater of a general hospital and a psychiatric center in Switzerland. We related the toxicity data to predicted concentrations in different wastewater streams to assess the overall risk potential for different scenarios, including conventional biological pretreatment in the hospital and urine source separation. The concentrations in wastewater were estimated with pharmaceutical usage information provided by the hospitals and literature data on human excretion into feces and urine. Environmental concentrations in the effluents of the exposure scenarios were predicted by estimating dilution in sewers and with literature data on elimination during wastewater treatment. Effect assessment was performed using quantitative structure-activity relationships because experimental ecotoxicity data were only available for less than 20% of the 100 pharmaceuticals with expected highest loads. As many pharmaceuticals are acids or bases, a correction for the speciation was implemented in the toxicity prediction model. The lists of Top-100 pharmaceuticals were distinctly different between the two hospital types with only 37 pharmaceuticals overlapping in both datasets. 31 Pharmaceuticals in the general hospital and 42 pharmaceuticals in the psychiatric center had a risk quotient above 0.01 and thus contributed to the mixture risk quotient. However, together they constituted only 14% (hospital) and 30% (psychiatry) of the load of pharmaceuticals. Hence, medical consumption data alone are insufficient predictors of environmental risk. The risk quotients were dominated by amiodarone, ritonavir, clotrimazole, and diclofenac. Only diclofenac is well researched in ecotoxicology, while amiodarone, ritonavir, and clotrimazole have no or very limited experimental fate or toxicity data available. The presented computational analysis thus helps setting priorities for further testing. Separate treatment of hospital wastewater would reduce the pharmaceutical load of wastewater treatment plants, and the risk from the newly identified priority pharmaceuticals. However, because high-risk pharmaceuticals are excreted mainly with feces, urine source separation is not a viable option for reducing the risk potential from hospital wastewater, while a sorption step could be beneficial.

QSAR analysis and specific endpoints for classifying the physiological modes of action of biocides in synchronous green algae.

We propose the use of additional physiological endpoints in the 24h growth inhibition test with synchronous cultures of Scenedesmus vacuolatus for the classification of physiological modes of toxic action of chemicals in green algae. The classification scheme is illustrated on the example of one baseline toxicant (3-nitroaniline) and five biocides (irgarol, diuron, Sea-Nine, tributyltin (TBT) and norflurazon). The well-established endpoint of inhibition of reproduction is used for an analysis of the degree of specificity of toxicity by comparing the experimental data with predictions from a quantitative structure-activity relationship (QSAR) for baseline toxicity (narcosis). For those compounds with a toxic ratio greater than 10, i.e. a 10 times higher effect in reproduction than predicted by baseline toxicity, additionally the physiological endpoints inhibition of photosynthesis, cell division and cell volume growth were experimentally assessed. Depending on the relative sensitivity of the different endpoints the chemicals were classified into five different classes of modes of toxic action using a flow chart that was developed in the present study. The advantage of the novel classification scheme is the simplicity of the experimental approach. For the determination of the inhibition of reproduction, the cell size and numbers are quantified with a particle analyzer. This information can be used to derive also the physiological endpoints of cell volume growth and inhibition of cell division. The only additional measurement is the inhibition of the photosynthesis efficiency, which can be easily performed using the non-invasive saturation pulse method and pulse-modulated chlorophyll fluorometry with the Tox-Y-PAM instrument. This mechanistic approach offers a great future potential in ecotoxicology for the physiological mode of action classification of chemicals in algae, which should be a crucial step considered in the risk assessment of chemicals.