Wastewater Surveillance for Benzodiazepines in Wuhu, China: Occurrence, Removal, and Consumption Patterns

Abstract

Benzodiazepines (BZDs), potent sedative and hypnotic drugs widely prescribed in psychiatry, pose a high risk of dependence and are globally abused. This study used wastewater-based epidemiology to investigate the consumption patterns of BZDs across four wastewater treatment plants (WWTPs) in Wuhu, China. A total of 16 BZDs and three metabolites were detected in influents and effluents, with concentrations reaching up to 90 ng/L (quetiapine fumarate) and 18.4 ng/L (diazepam). Most BZDs had a poor removal efficiency except quetiapine fumarate (>98% removal). The consumptions of BZDs in WWTPs ranged from <0.02 (lormetazepam) to 2700 mg/day/1000 people (quetiapine fumarate). Seasonal variation was found in BZD usage, where the consumptions in winter and spring were significantly higher than those in summer and autumn. It was worth noting that nimetazepam may be abused during the sampling campaign. Urban areas with higher housing prices match higher BZD consumption, correlating with greater stress and insomnia rates. This study reveals the relationship between socioeconomic factors and BZD consumption patterns, provide a new path to addressing community public health.