Assessment of illicit drug use in Seoul, the capital of South Korea for 21 days by wastewater-based epidemiology.

22 illicit drugs were monitored in Seoul, the capital of South Korea for 21 days using wastewater-based epidemiology to assess the drug usage patterns for the first time by region and social status. Among the targeted compounds, 10 were detected, with consistent detection of methamphetamine in samples over the entire sampling period. In addition, ketamine had the highest estimated consumption rate at 47.5 mg/day/1000 people, followed by methamphetamine at 12.5 mg/day/1000 people. Methamphetamine and MDMA(3,4-methylenedioxymethamphetamine) exhibited relatively stable daily patterns, with coefficients of variation of 7.03 %, and 13.4 % respectively. Furthermore, no statistically significant differences were observed between weekends and weekdays for all compounds (Mann-Whitney Rank Sum test, p > 0.05). Statistically significant regional differences in drug consumption were observed for methamphetamine, MDMA, and ketamine (Mann-Whitney Rank Sum test, p < 0.05). These differences were found to be related to average annual income and educational levels.