Occurrence and fate of rosuvastatin, rosuvastatin lactone, and atorvastatin in Canadian sewage and surface water samples

Rosuvastatin (RST) and atorvastatin (ATO) are prescription drugs and members in the statin family used for the treatment of elevated cholesterol levels. A method using solid-phase extraction and liquid chromatography–tandem mass spectrometry (LC–MS/MS) for the determination of ATO, RST and its metabolite rosuvastatin lactone (RSTL) in sewage and surface water samples has been developed. In the influent and effluent samples collected from 11 sewage treatment plants located in Ontario, Canada, ATO, RST, and RSTL were detected in all samples with median concentrations of 166 ng L−1 (influent) and 77 ng L−1 (effluent) for ATO, 448 ng L−1 (influent) and 324 ng L−1 (effluent) for RST, as well as 158 ng L−1 (influent) and 41 ng L−1 (effluent) for RSTL. Due to the inter-conversion between RST and RSTL, the total concentration of RST and RSTL in a sewage sample should be reported. The median removal rate by wastewater treatment was 66% for ATO and 22% for RST and RSTL combined. These statins were quite persistent in sewage. After a storage period of 21 and 62 days, there was only a slight decrease in ATO concentration and no change in the total RST concentrations. These three compounds were also detected in a number of surface water samples at low ng L−1 concentrations. This is the first reported occurrence and fate of RST and RSTL in the Canadian aquatic environment.