Evaluating wastewater surveillance for estimating pharmaceutical use

This study assessed whether measuring active pharmaceutical ingredients (APIs) in untreated municipal wastewater can reliably estimate regional medicine use. Researchers analysed 53 APIs across three wastewater treatment plants in Stockholm (2004–2021) and compared the detected amounts with comprehensive sales data. They developed conversion factors (CFs) linking wastewater concentrations to actual consumption and found that, although CFs varied widely between APIs, the recovered wastewater loads were generally equal to or lower than estimated usage. CF variability was relatively low for most APIs, and predictions for a third treatment plant were accurate within a twofold margin for 68% of substances. Results also aligned well with independent international data. The study shows that wastewater surveillance can estimate medicine use for most APIs with reasonable accuracy, offering a valuable tool for regions lacking pharmaceutical use data—though it may struggle to detect small changes in consumption.