South Korea detects 31 illegal drugs in wastewater, synthetic cannabinoids most prevalent

South Korea's Ministry of Food and Drug Safety (MFDS) released results of its 2025 illegal drug usage survey, analyzing wastewater from 60 sites—including 34 major treatment plants, 16 urban sewer zones and 10 locations near nightlife venues. The analysis identified 31 different illegal substances, with synthetic cannabinoids accounting for 68% of detections (21 distinct variants). Methamphetamine, known locally as philopon, was found in all 34 treatment plants, leading the agency to estimate an average daily consumption of 85 mg per 1,000 residents (roughly one user per 10,000 people). During the Halloween period, samples taken near clubs revealed eight “club‑drug” substances—including cocaine, MDMA (ecstasy) and ketamine—double the four substances detected in regular weekend samplings.

The survey expanded the range of analytes from 15–22 to 243, meaning the rise in detected drug types does not necessarily indicate a surge in overall use. MFDS plans to share the location‑specific findings with police, prosecutors and local governments to aid prevention and enforcement, and will continue to broaden sampling in urban and high‑risk areas.