Understanding Illicit Drug Use Trends During the Carnival Holiday in the Brazilian Capital Through Wastewater Analysis

Cocaine and cannabis consumption during after the 2019 Carnival holiday were assessed using wastewater-based epidemiology (WBE) in capital of Brazil, Brasília. The substances 11-nor-9-carboxy-?9-tetrahydrocannabinol (THC-COOH), cocaine (COC), benzoylecgonine (BE), cocaethylene (COE) monitored composite samples (24 h) collected entrance North-Wing (NW) South-Wing (SW) wastewater treatment plants (WWTP) for 15 consecutive days, including holiday. Aliquots (100 ml) enriched with isotope-labeled standards, solid-phase extracted analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Results reveal higher (average 2.8 ± 0.7 g/1000inh/day) compared to subsequent period 1.7 0.3 g/1000inh/day). Cannabis (THC) use was also (14 5 but differences not significative (unpaired t -test, 95%) following days (11 3 g/1000inh/day), where remained relatively constant corroborating that overall is less affected occasional abuse. Regarding cocaine, an unusual low noticed weekend immediately Holiday, indicating lower demand or supply issues. Higher observed throughout entire sampling area covered NW-WWTP, probably due proportion young people. This investigation brings first data on Brazil WBE confirms this strategy as a well consolidate tool estimating illicit drug