Occurrence of pharmaceuticals and cocaine in the urban drainage channels located on the outskirts of the São Vicente Island (São Paulo, Brazil) and related ecological risk assessment

“Wealth by the sea and poverty away from the sea breeze” is a metaphor that mirrors what happens along the Brazilian coastal zone, namely in São Vicente Island, São Paulo, Brazil. Due to the high cost of the properties on this shore, the impoverished population started to migrate to the northern outskirts of the island (away from the tourist beaches), potentiating the emergence of poor housing conditions, namely stilt-house slums. Consequently, the urban drainage channels across these outskirts neighbourhoods are potentially contaminated by human wastes. In this context, the occurrence and preliminary ecological risk assessment of eleven pharmaceuticals of various therapeutic classes (including cocaine and its primary metabolite, benzoylecgonine) were investigated, for the first time, in five urban drainage channels whose diffuse loads flow continuously to the estuarine waters of São Vicente Island. The results showed the widespread presence of these environmental stressors in all urban channels analysed, namely losartan (7.3–2680.0 ng/L), caffeine (314.0–726.0 ng/L), acetaminophen (7.0–78.2 ng/L), atenolol (6.2–23.6 ng/L), benzoylecgonine (10.2–17.2 ng/L), furosemide (1.0–7.2 ng/L), cocaine (2.3–6.7 ng/L), carbamazepine (0.2–2.6 ng/L), diclofenac (1.1–2.5 ng/L), orphenadrine (0.2–1.1 ng/L) and chlortalidone (0.5–1.0 ng/L). The overall total estimated load of pharmaceuticals and personal care products flowing to the estuarine waters of São Vicente Island is on the order of 41.1 g/day. The ecological risk assessment revealed a great environmental concern for São Vicente Island, ranging between low (e.g. carbamazepine and cocaine) and moderate to high (e.g. caffeine, acetaminophen and losartan) threats for the aquatic biota. Therefore, initiatives promoting basic sanitation, land-use regularisation and population awareness are highly recommended. GRAPHICAL ABSTRACT: [Image: see text] SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s11356-022-19736-4.