Wide-scope screening of pharmaceuticals, illicit drugs and their metabolites in the Amazon River

Only a limited number of households in the Amazon are served by sewage collection or treatment facili-ties, suggesting that there might be a significant emission of pharmaceuticals and other wastewater con-taminants into freshwater ecosystems. In this work, we performed a wide-scope screening to assess the occurrence of pharmaceuticals, illicit drugs and their metabolites in freshwater ecosystems of the Brazil-ian Amazon. Our study included 40 samples taken along the Amazon River, in three of its major tribu-taries, and in small tributaries crossing four important urban areas (Manaus, Santarem, Macapa, Belem). More than 900 compounds were investigated making use of target and suspect screening approaches, based on liquid chromatography coupled to high-resolution mass spectrometry with ion mobility sep-aration. Empirical collision-cross section (CCS) values were used to help and confirm identifications in target screening, while in the suspect screening approach CCS values were predicted using Artificial Neu-ral Networks to increase the confidence of the tentative identification. In this way, 51 compounds and metabolites were identified. The highest prevalence was found in streams crossing the urban areas of Manaus, Macapa and Belem, with some samples containing up to 30 -40 compounds, while samples taken in Santarem showed a lower number (8 -11), and the samples taken in the main course of the Amazon River and its tributaries contained between 1 and 7 compounds. Most compounds identified in areas with significant urban impact belonged to the analgesics and antihypertensive categories, followed by stimulants and antibiotics. Compounds such as caffeine, cocaine and its metabolite benzoylecgonine, and cotinine (the metabolite of nicotine), were also detected in areas with relatively low anthropogenic impact and showed the highest total prevalence. This study supports the need to improve the sanita-tion system of urban areas in the Brazilian Amazon and the development of follow-up studies aimed at quantifying exposure levels and risks for Amazonian freshwater biodiversity. (c) 2021 Elsevier Ltd. All rights reserved.

Automated summary

A study conducted in the Brazilian Amazon revealed a significant presence of pharmaceuticals and contaminants in freshwater ecosystems, with urban areas showing higher prevalence of compounds such as analgesics and antihypertensives. It highlights the need to improve sanitation systems in urban areas and calls for further research on exposure levels and risks to Amazonian freshwater biodiversity.