Pharmaceutical Residues in Human Urine from Patients Under Antiretroviral Regimens and Self-Reported Healthy Individuals Before and After Three Months’ Storage: Implication for Agricultural Reuse in Pretoria, South Africa

Background/Objectives: Pharmaceutical residues in human urine have raised serious concerns about the safe reuse of urine in agriculture. The current study investigates and compares the concentrations of pharmaceuticals in urine samples collected from male patients undergoing active antiretroviral regimens and self-reported “healthy individuals” at a government hospital in Pretoria, South Africa, and determines how the residues changed during three months of ambient storage, which is the usual recommendation before use in agriculture. Methods: The urine samples were collected in a plastic bottle to prevent fecal contamination, and 15 targeted compounds were analyzed using solid-phase extraction and liquid chromatography–mass spectrometry. The linearity ranged from 0.9910 to 0.9999, 75.5% to 99.1% for recovery, and intra-day and inter-day precision were below 6%. The urine from each group was collected into one pooled sample and then analyzed both pre- and post-storage. Results: Thirteen pharmaceuticals were detected in urine from patients on regular medication before storage; in “healthy individuals”, detections rose from eight to twelve after storage. Concentrations in the composite samples after storage were higher for some of the compounds but lower for others, including caffeine, nevirapine, prednisolone and 17α-ethinylestradiol. Metformin was highest overall at 1186.25 µg/L and remained at 806.68 µg/L after storage. The highest concentration for all the pharmaceuticals was reported for metformin, with a value of 1186.25 µg/L, occurring in the group of patients on a regular regimen. There could be a possibility that the rise can be attributed to the hydrolysis of conjugated metabolites during storage; however, no analysis of conjugates was carried out. Conclusions: This study shows the need for appropriate treatment of human urine prior to its reuse as fertilizer and echoes the importance of further research into human exposure pathways and effective pharmaceutical removal strategies.