New Psychoactive Substances Discharged at Rest Areas along Interstate Highway in Kentucky - Wastewater Analysis

New psychoactive substances (NPS) such as synthetic opioids, synthetic cannabinoids, synthetic cathinones, and piperazines are intermittently introduced in the illicit drug supply chain. To monitor this ever-changing landscape of NPS, wastewater-based epidemiology offers a comprehensive, non-invasive, cost-effective, and time-efficient approach. Twenty-three forensically identified NPS were simultaneously analyzed in wastewater samples collected from rest areas along the interstate highway in Kentucky over twelve months using solid phase extraction and ultra-performance liquid chromatography coupled with tandem mass spectrometry. Para-hydroxy methamphetamine and 1-(3-chlorophenyl) piperazine were the most frequently detected NPS (detection frequency, df = 100%). The mean mass load of para-hydroxy methamphetamine (methamphetamine corrected 85.9 mg/d/1000 people) and MAB- CHMINACA (9.06 mg/d/1000 people) were among the highest. Mitragynine and 4-methyl pentedrone have recently been associated with overdose deaths. In wastewater samples, mitragynine and 4-methyl pentedrone were detected (df ≥ 98%) at 36.4 and 28.5 mg/d/1000 people, respectively. This study shows that wastewater surveillance at the rest areas can potentially complement the existing forensic surveillance, such as components of the National Drug Early Warning System, in detecting NPS outbreaks.