Environmental release of oseltamivir from a Norwegian sewage treatment plant during the 2009 influenza A (H1N1) pandemic.

During the 2009 influenza type A(H1N1) pandemic, the antiviral drug oseltamivir (OP, Tamiflu®) was extensively used for treatment and prophylaxis after recommendation from World Health Organisation (WHO). Previous studies have indicated that the pharmaceutically active metabolite of OP, oseltamivir carboxylate (OC), is not readily degraded in sewage treatment plants (STPs) and therefore will be released into receiving waters in elevated concentrations during a pandemic outbreak of influenza. A method for analyzing OP and OC in wastewater by UPLC-TOF has been developed and validated. This analytical method has been used to study the release of OP and OC from a sewage treatment plant outside Oslo, Norway during the 2009 pandemic. Daily flow-proportional influent and effluent samples from 11 weeks covering the main wave of the influenza pandemic were analyzed, and the observed trend in OP and OC concentrations closely followed the trend in percentage of medical consultations caused by influenza-like illness. Concentrations in wastewater influent were in the range of 5-529 ng/L and 28-1213 ng/L for OP and OC, respectively. Concentration data from the 54 influent/effluent sample sets suggest STP removal in the range of -0.8% to 8% for OP and -14% to 0.6% for OC. Statistical analysis of the data sets was inconclusive in determining a removal rate different from 0.