Early Warning from Wastewater: Detection of Emerging Opioid Cychlorphine in Rural Tennessee

High Resolution Image Download MS PowerPoint Slide The rapid succession of synthetic drug waves in the United States─from the rise of fentanyl in 2013 to the xylazine and nitazene adulterants in 2019 and recent emergence of cychlorphine in 2025─underscores the highly dynamic and continuously evolving illicit drug market. Since November 2025, public health authorities have reported the emergence of cychlorphine across multiple jurisdictions despite limited analytical capability. In this study, wastewater collected from 12 catchments in East Tennessee─ an area reporting most cychlorphine-involved overdose cases─was analyzed using a validated liquid chromatography mass spectrometry method. Cychlorphine was detected in seven samples and quantified in four samples from one rural community situated along Interstate 75, with a mean concentration of 8.69 ± 1.60 ng/L. Population and flow normalized mass loads ranged from 2.61 to 5.48 mg/day/1000 people, indicating sustained community-level exposure. To our knowledge, this study provides the first evidence of cychlorphine occurrence in wastewater samples. These findings demonstrate the wastewater-based epidemiology as an early warning system for emerging synthetic opioids. Implementing comprehensive and continuous wastewater monitoring can provide near-real-time insights into drug use trends, enabling proactive public health responses, informing harm-reduction strategies, and strengthening emergency preparedness to mitigate the impact of highly potent synthetic opioids.