Cracking the code - an integrated wastewater-based approach for a more comprehensive assessment of current trends in cocaine and crack use in Switzerland.

In Switzerland, as in the rest of Europe and beyond, increasing cocaine and crack use, along with related social and health harms, is a serious concern to authorities. The aim of this study was to provide objective data on this complex situation by integrating wastewater analysis, targeting benzoylecgonine (BE) and anhydroecgonine methyl ester (AEME) in 13 Swiss cities from 2021 to 2024, with street-level cocaine purity data obtained from near-infrared spectroscopy analyses, and survey data on user populations and administration routes used to compute a weighted BE excretion rate. Results highlighted strong weekly and spatial trends in BE loads and an overall increase in cocaine consumption, part of which could be attributed to the increase in cocaine purity. Unexpectedly, AEME loads did not increase; however, spatial trends were similar to those of BE, highlighting a correlation between AEME and BE loads. Overall, evolutions of crack cocaine use must be accounted for when monitoring general cocaine consumption through BE wastewater loads due to large differences in excretion rates. Thus, triangulation of multiple data sources allowed for a more comprehensive and nuanced understanding of the cocaine and crack cocaine situation in Switzerland, which is crucial to the implementation of tailored and efficient measures.