Prevalence of selected pharmaceuticals in surface water receiving untreated sewage in northwest Pakistan.

This study investigated the occurrence of four non-steroidal anti-inflammatory drugs (NSAIDs) and four benzodiazepines/anti-depressants (ADs) in municipal wastewater in Mardan city, Pakistan, and in River Kabul and River Indus receiving untreated sewage. Liquid chromatography with a triple quadrupole tandem mass spectrometry (LC-MS/MS) was used for the analysis of paracetamol, diclofenac, ibuprofen, and codeine (NSAIDs) and diazepam, bromazepam, lorazepam, and temazepam (ADs). Except codeine and lorazepam, all the target compounds were observed in sewage and surface water in various concentrations. In sewage, paracetamol was found at the higher end (32.4 µg/L) of the reported ranges in literature for other countries. Results of river samples showed that the target compounds were usually lower in concentration than the respective EC50 values for aquatic organisms. However, the levels for paracetamol and ibuprofen were critical depicting the consequence of untreated disposal. Environmental risk assessment by estimating the risk quotient (RQ) as the ratio of measured environmental concentration and predicted no-effect concentration showed medium to high (RQ > 1 and 0.1 < RQ < 1) risk from paracetamol and ibuprofen to aquatic organisms in River Kabul and Kalpani stream, Pakistan.