Wastewater surveillance to assess cocaine and methylenedioxymethamphetamine use trends during a major music festival in Brazil.

Wastewater-based epidemiology was applied in northeastern Brazil during a dance festival, revealing that cocaine consumption doubled during the event days. The daily drug loads were 0.95 ± 0.03 to 11.4 ± 0.4 g/day for BE, 1.8 ± 0.4 to 7.6 ± 0.3 g/day for COC, 0.04 ± 0.02 to 0.19 ± 0.02 g/day for COE, and 0.08 ± 0.02 to 0.80 ± 0.02 g/day for MDMA.