Prioritization of Active Pharmaceutical Ingredients in Hospital Wastewater

A large amount of residues from active pharmaceutical ingredients (API) that are currently in use are known to reach aquatic ecosystems and have potentially adverse effects on living organisms. Prioritization methods are useful tools for both regulation and surveillance purposes in the environmental policy of APIs. Their use has largely increased over the last decade, and the different existing methodologies can lead to large discrepancies between the highlighted substances. This chapter aims at discussing studies conducted in the context of hospitals. Perhaps more important than the results themselves, the methodologies with the set of selected criteria are discussed, as well as their advantages and associated uncertainties. A case study of API prioritization applied to a Swiss university hospital is presented with two different approaches: a ranking-based OPBT approach (Occurrence, Persistence, Bioaccumulation, and Toxicity) and an environmental risk assessment (ERA), with the calculation of risk quotient (RQ). The ERA results combined with those of other studies dealing with ERA-based API prioritization in hospitals highlighted several compounds presenting high risks for the aquatic ecosystems (RQ > 1): antibiotics (ciprofloxacin, amoxicillin, piperacillin, azithromycin), anti-inflammatory drugs (diclofenac, mesalazine), as well as the hormone estradiol and the antidiabetic metformin. Nevertheless, only the antibiotic ciprofloxacin was commonly determined as problematic. Finally, the most critical issues for API prioritization in hospitals were identified from the literature overview and the results of the presented case study: handling of the consumption data, involvement of expert judgment, uncertainties linked with the predicted environmental concentration (PEC) calculation, and quality of the hazard evaluation. Although prioritization procedures applied to hospitals can be burdensome to apply in practice and many associated uncertainties remain, they represent essential tools to establish lists of priority molecules to follow via monitoring programs and allow their theoretical risk assessment.