"In 2022, generally very low levels of ketamine residues in municipal wastewater were reported by 15 cities, with the highest mass loads being detected in cities in Denmark, Spain, Italy and Portugal (see the figure Ketamine residues in wastewater in selected European cities, 2022, below)."
Source
European Monitoring Centre for Drugs and Drug Addiction (2023), European Drug Report 2023: Trends and Developments, last accessed July 9, 2023.
