Estimating cocaine consumption in the Brazilian Federal District (FD) by sewage analysis

This is the first report on the occurrence of cocaine (COC) and benzoylecgonine (BE) residues in six samples collected from different wastewater treatment plants (WTP) located in the Brazilian Federal District (FD). Concentrations of BE in the influent sewage were used to calculate cocaine consumption (kg year-1 per 1000 inhabitants) for each region attended by the WTP from two sampling campaigns (March and June, 2010). Among the WTP studied, samples from Samambaia showed higher concentrations (from 3866 to 2477 ng L-1 of BE and 805 to 579 ng L-1 of COC) and doses per inhabitants (more than 13 doses inhabitant-1 per year). The extrapolation to the whole FD population points out to an annual consumption reaching 1.0 ton of free base cocaine, or 1.1 tons of cocaine hydrochloride. The work also addresses the influence of the cocaine presentation form (free base or hydrochloride) and the integration with chemical profiling results in a more realistic estimate, mainly concerning the viewpoints of forensics and law enforcement.