An Initial Survey of Targeted Anticancer Drug Residues in Municipal Wastewater of Bangkok, Thailand

The increasing prevalence of cancer in Thailand over the past decade has resulted in a substantial rise in the use of anticancer drugs, which are eventually discharged into municipal wastewater through hospital and domestic effluents. The inability of conventional wastewater treatment systems to completely remove these pharmaceuticals has been widely reported. The continuous release of these emerging anticancer agents into aquatic environments reduces water quality and threatens biodiversity. Even at trace levels, these compounds may act as persistent pollutants capable of impairing ecosystem. This study investigated the occurrence and concentration levels of three widely used chemotherapeutic agents including cyclophosphamide (COP), doxorubicin (DOX), and vincristine (VIN) in Bangkok’s municipal wastewater to evaluate their potential environmental risks. Thirty-two influent and effluent wastewater samples were collected from eight large-scale wastewater treatment plants (WWTPs) from October 2024 to January 2025. Samples were processed using solid-phase extraction (SPE) and analyzed by liquid chromatography–triple quadrupole mass spectrometry (LC–MS/MS). The analytical method demonstrated high precision and reproducibility, with relative standard deviations (%RSD) below the 20% acceptance limit for all compounds. Method accuracy ranged from 81.84% to 107.21%. Results showed the presence of only COP in almost influent and effluent at levels ranging from 0.26 to 2.06 µg/L. In contrast, DOX and VIN levels remained consistently below the limits of quantitation (LOQ) in all WWTP samples. This study establishes the first baseline for COP, DOX, and VIN contamination in Bangkok’s municipal wastewater. Notably, the residue of COP in wastewater suggests that current wastewater treatment facilities in Thailand are insufficient for its removal, posing a potential long-term risk to local aquatic ecosystems.