Pharmaceuticals and iodinated contrast media in a hospital wastewater: A case study to analyse their presence and characterise their environmental risk and hazard

Abstract

This work analyses the presence of twenty-five pharmaceutical compounds belonging to seven different therapeutic groups and one iodinated contrast media (ICM) in a Spanish medium-size hospital located in the Valencia Region. Analysis of the target compounds in the hospital wastewater was performed by means of solid phase extraction (SPE) followed by liquid chromatography-tandem mass spectrometry analysis (HPLC-MS/MS). A screening level risk assessment combining the measured environmental concentrations (MECs) with dose-response data based on Predicted No Effect Concentration (PNEC) was also applied to estimate Hazard Quotients (HQs) for the compounds investigated. Additionally, the environmental hazard associated to the various compounds measured was assessed through the calculation of the Persistence, Bioaccumulation and Toxicity (PBT) Index, which categorizes compounds according to their environmentally damaging characteristics. The results of the study showed the presence of twenty-four out of the twenty-six compounds analysed at individual concentrations ranging from 5ngL^-1 to 2mgL^-1. The highest concentrations corresponded to the ICM iomeprol, found at levels between 424 and 2093μgL^-1, the analgesic acetaminophen (15-44μgL^-1), the diuretic (DIU) furosemide (6-15μgL^-1), and the antibiotics (ABIs) ofloxacin and trimethoprim (2-5μgL^-1). The lowest levels corresponded to the anti-inflammatory propyphenazone, found at concentrations between 5 and 44ngL^-1. Differences in terms of concentrations of the analysed compounds have been observed in all the therapeutic groups when comparing the results obtained in this and other recent studies carried out in hospitals with different characteristics from different geographical areas and in different seasons. The screening level risk assessment performed in raw water from the hospital effluent showed that the analgesics and anti-inflammatories (AAFs) acetaminophen, diclofenac, ibuprofen and naproxen, the antibiotics (ABIs) clarithromycin, ofloxacin and trimethoprim, and the β-blocker (BBL) propranolol were present at concentrations leading to HQ values higher than 10, thus indicating high risk. When applying a factor to take into account potential dilution and degradation processes, only the compound ibuprofen showed a HQ higher than 1. Likewise, the cumulative HQ or Toxic Units (TUs) calculated in the raw water for each of the therapeutic groups studied showed that these three classes of drugs were at concentrations high enough to potentially generate high risk to aquatic organisms while taking into account possible dilution and degradation processes only one of them, the AAFs can be considered to represent high risk. Finally, the environmental hazard assessment performed showed that the AAFs diclofenac and ibuprofen and the ABI clarithromycin have the highest, maximum value of 9 of PBT Index due to their inherent environmentally damaging characteristics of persistence, bioaccumulation and toxicity.The methodology followed in the present case study can be taken as a novel approach to classify and categorize pharmaceuticals on the basis of their occurrence in hospital effluents, their derived environmental risks, and their associated environmental hazard. This classification becomes important because it can be used as a model or orientation for hospitals in the process of developing environmentally sustainable policies and as an argument to justify the adoption of advanced, specific treatments for hospital effluents before being discharged into the public sewage system