October 23, 2017 by Dean Leverett


I have been involved in the UKWIR Chemicals Investigation Programme (CIP) for some considerable time (both while at wca and in my previous roles at the Environment Agency), mainly dealing with technical issues associated with sampling, analysis and PNEC derivation for so-called ‘emerging contaminants’ (primarily pharmaceuticals).

I have contributed to a recently published paper reporting 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 both Phase 1 and Phase 2 of the UKWIR CIP.

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 wastewater treatment works in the UK. The majority of substances studied were removed to a high degree, although with significant variation, both within and between wastewater treatment works. 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 much as 13% of all wastewater treatment works may cause exceedances of estimated riverine PNECs after mixing of their effluents with receiving waters. It is, however, important to note that the overall degree of risk is driven by the PNEC derivation, 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.

The full paper is available in Science of the Total Environment Volumes 613-614, Issue 10 and the full text can also be accessed here (free access to full article until 15/11/2017).