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This work reports on the variation in wastewater treatment works (WwTW) influent concentrations of a wide variety of active pharmaceutical ingredients (APIs), their removal efficiency, effluent concentrations and potential risks to the aquatic environment. The research is based on data generated from two large UK-wide WwTW monitoring programmes. Taking account of removal of parent compound from the aqueous phase during treatment in combination with estimates of dilution available it is possible to prioritise the APIs of greatest risk of exceeding estimates of predicted no effect concentrations (PNEC) in receiving waters for all WwTW in the UK. The majority of substances studied were removed to a high degree, although with significant variation, both within and between WwTW. Poorer removal (between influent and effluent) was observed for ethinyloestradiol, diclofenac, propranolol, the macrolide antibiotics, fluoxetine, tamoxifen and carbamazepine. All except the last two of these substances were present in effluents at concentrations higher than their respective estimated PNEC (based on measurement of effluents from 45 WwTW on 20 occasions). Based on available dilution data as many as 890 WwTW in the UK (approximately 13% of all WwTW) may cause exceedances of estimated riverine PNECs after mixing of their effluents with receiving waters. The overall degree of risk is driven by the toxicity value selected, which in itself is controlled by the availability of reliable and relevant ecotoxicological data and consequently the safety factors applied. The dataset and discussion, provides information to assist in the future management of these types of chemicals.

Background: A decision tree has been developed for evaluating risks posed by combined exposures to multiple chemicals. The decision tree divides combined exposures of humans and ecological receptors into groups where one or more components are a concern by themselves, where risks from the combined exposures are of low concern, and where there is a concern for the effects from the combined exposures but not from individual chemicals. This paper applies the decision tree to real-world examples of exposures to multiple chemicals, evaluates the usefulness of the approach, and identifies issues arising from the application.

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Reliable ecotoxicity data are required to derive thresholds protective for aquatic life that are scientifically defensible and practically implementable as environmental risk assessment and management tools. Much of the data that have been used to derive thresholds for environmental quality have been collected for temperate species. There are concerns that due to a lack of data for the different species present in tropical ecosystems, they may not be adequately protected by thresholds derived from temperate species. In the present study, chronic ecotoxicity data for nickel and freshwater species from different climatic regions have been collated. Comparisons were performed between tropical and temperate datasets on the basis of the threshold values and overall distributions of the ecotoxicity data, as well as between groups of species and closely related species from different climatic regions. The analysis indicated that the sensitivities of tropical and temperate species cover similar ranges. An approach based on the inclusion of as diverse a range of taxa as possible is recommended to ensure the protection of sensitive species in both temperate and tropical ecosystems. Environ Toxicol Chem 2019;38:1211–1220. © 2019 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals, Inc. on behalf of SETAC.