Seasonal monitoring, ecological risk assessment, and prioritization of pharmaceuticals in a tropical semi-enclosed bay (Santos, São Paulo coast, Brazil)

Research on the occurrence and seasonal monitoring of pharmaceutically active compounds (PhACs) in estuarine and coastal waters has intensified recently. However, few studies have been conducted with PhACs flowing into the marine waters of South America (such as Brazil). Against this backdrop, the aims of this study were: (i) evaluate, for the first time, the seasonal occurrence throughout a year and the potential ecological risks of ten selected PhACs in marine bathing waters from Santos Bay, São Paulo, Brazil (a tropical low-wave energy semi-closed bay); and (ii) develop a list of high-priority PhACs for the monitoring based on "occurrence, persistence, bioaccumulation, and toxicity" criteria (OPBT). Four water sampling campaigns were carried out throughout the four seasons of the year. The results showed that: (i) ten PhACs (namely, caffeine/CAF (87.20–567.23 ng/L); carbamazepine/CAR [below the limit of quantification (<LOQ) to 3.42 ng/L]; citalopram/CIT (<LOQ to 2.98 ng/L); acetaminophen/ACE (<LOQ to 4.00 ng/L); diclofenac/DIC (<LOQ to 5.17 ng/L); orphenadrine/ORP (<LOQ to 3.92 ng/L); atenolol/ATE (<LOQ to 2.98 ng/L); losartan/LOS (<LOQ to 3.98 ng/L); enalapril/ENA (<LOQ to 2.23 ng/L); and furosemide/FUR (<LOQ to 3.24 ng/L), were found in Santos Bay; (ii) the "mass gathering" in Santos city during New Year holiday contributed significantly to increase the mass load of nine PhACs in marine waters; (iii) the ecological risk assessment revealed great environmental concern for the aquatic ecosystem, since the results suggest low to moderate risks of CAF, followed by LOS > ACE > DIC and CAR to algae, crustaceans, and fishes; (iv) Finally, regarding the OPBT ranking, the DIC was the highest-priority PhAC in Santos Bay, followed by: ORP > LOS > CIT > CAR > FUR > ATE > CAF > ACE > ENA.