Pharmaceutical Concentrations and Loads in Hospital Effluents: Is a Predictive Model or Direct Measurement the Most Accurate Approach?

The pharmaceutical concentration and load in a hospital effluent may be known through the adoption of predictive models based on medicament consumption data, or through direct measures. Both methods present strengths and weaknesses, and advantages and drawbacks. This chapter presents and compares the predicted and measured concentrations and loads found by different authors for a large number of pharmaceuticals in hospital effluents. It then discusses the main factors influencing the predicted values, as well as those affecting measured ones and estimates the range of variability of each model parameter (pharmaceutical consumption data, excretion factor and wastewater volume). It then presents the results of the sensitivity analysis carried out for the predicted concentrations and the uncertainty analysis for measured ones (in the latter case, by evaluating the contribution due to sampling protocol, chemical analysis and flow rate measurement) and discusses the most critical parameters in both strategies. The study concludes with some recommendations for reducing uncertainties in measured and predicted data, thus improving the accuracy and reliability of the results.