RESUMO
UNLABELLED: Contamination of natural aquatic environments with human-use pharmaceuticals poses a significant potential threat to local ecosystems. However studies of the risk assessment of this contamination are limited, in part because currently the environmental concentration prediction is logistically and technically difficult to perform. In this study, 1) a strategic method to determine occurrence and risk of pharmaceutical compounds in an aquatic environment is proposed, and 2) this method is applied to study ten human-use pharmaceuticals in Taiwan's Sindian river, which traverses and supplies drinking water for Taipei, a major metropolitan center. In river-water samples collected over a three-week period, concentrations of NSAIDs (acetaminophen, diclofenac, ibuprofen, naproxen, and ketoprofen), steroids (estrone, 17alpha-ethinylestradiol and 17beta-estradiol), the anti-hypertensive agent propranolol, and the lipid regulator gemfibrozil were found at ng/L to microg/L levels; night-time concentrations were often doubled or even greater, compared to day-time levels. With the exception of the estrogens, predicted environmental concentrations (PECs) of the target pharmaceuticals agreed well with measured environmental concentrations (MECs). CONCLUSIONS: In the Sindian river, which is impacted by both regional and hospital discharges, the pattern of pharmaceutical occurrences and concentrations observed here is due to variations in source release rather than to natural attenuation phenomena. In addition, the environmental risk posed by acetaminophen, ibuprofen, and the estrogens was observed to be imminent, while risk from the other drugs targeted was found to be lower, even when maximum MECs were considered.