Informing pharmaceutical regulation in China: Risk-based priority ranking across nine river basins.

Pharmaceuticals are widely detected in surface waters, posing significant ecological and human-health risks. China is a major producer and consumer of pharmaceuticals, and widespread contamination has been reported in its surface waters. Regional differences in topography, hydrology, land use, and socioeconomic conditions can shape patterns of pharmaceutical exposure and risk, calling for priority lists tailored to individual river basins. However, previous studies mainly focused on national-scale assessments, selected river basins, or specific pharmaceutical classes. In this study, we systematically reviewed 226 peer-reviewed articles and compiled 8628 occurrence records for 158 pharmaceutical compounds. A multi-criteria prioritization framework that integrated both hazard and exposure potential was used to identify priority pharmaceuticals across nine river basins. Antibiotics were the most frequently detected class of pharmaceuticals, although most had low or moderate priority scores. Erythromycin, roxithromycin, and azithromycin were notable exceptions and ranked highly. Among nonantibiotic pharmaceuticals, estrone and ibuprofen ranked highly in all nine basins. Beyond these shared priorities, several pharmaceuticals showed distinct basin-specific priority pattern. Psychotropic medicines, including diazepam, fluoxetine, sertraline, and citalopram, were identified as priorities in highly urbanized basins, particularly the Haihe and Yangtze River basins. In the Yellow River Basin, the lipid modulator gemfibrozil was prioritized, while in the Pearl River Basin, the veterinary antibiotic salinomycin was prioritized. Combining the rankings with uncertainty estimates showed that high-priority compounds with low uncertainty should be considered for stringent monitoring and control, whereas compounds with high uncertainty require additional occurrence and toxicity data. These findings underscore the importance of basin-scale prioritization in capturing regional differences and provide a basis for tiered monitoring and management in China.