Environmental risk profiling of pharmaceuticals in surface waters in a tropical agro-livestock region of Costa Rica

An environmental risk assessment of pharmaceuticals was conducted in surface waters from a tropical agricultural region in Costa Rica to describe their potential effects in rural ecosystems. The study collected 58 surface water samples from 22 sampling points in an intensive pineapple cultivation area in the Northern Region of the country and analyzed pharmaceuticals using a multiresidue method by Ultra-High Performance Liquid Chromatography (UHPLC) coupled to a triple quadrupole mass spectrometer. Environmental risks were assessed using chronic (Hazard Quotient, HQ), acute (Toxic Units, TU), and antibiotic resistance selection (HQ_Res) risk assessments. Monitoring revealed contamination with 15 different pharmaceuticals, including a predominance of antibiotics and caffeine, which showed the highest concentrations (max 17.5 µg/L). The risk assessment identified that 10 of the 15 detected pharmaceuticals posed a moderate to high chronic risk to aquatic life; specifically, sulfathiazole, clarithromycin, caffeine, and ofloxacin were categorized as high-risk compounds (HQ > 1). Furthermore, ciprofloxacin and clarithromycin posed a high risk for the selection of antimicrobial resistance. Although acute risk was seldom described, it was mainly driven by pharmaceutical mixtures, with clindamycin identified as a high-risk compound for fish in one sample. The findings emphasize the critical need for surveillance and targeted mitigation strategies to address emerging threats, particularly antibiotics, in tropical agricultural landscapes.