Predicted environmental concentrations: A useful tool to evaluate the presence of cytostatics in surface waters

Cytostatic or anticancer drugs used in chemotherapy are administered in the order of tons per year in European countries. After administration, these compounds are excreted and reach the sewage system. Because of their poor elimination in wastewater treatment plants (WWTPs), a fraction of these compounds are finally released to surface waters and can produce genotoxic and mutagenic effects on aquatic organisms. Given that cancer incidence has increased over the last years and is foreseen to increase, it is anticipated that the consumption of cytostatic drugs will equally increase. Thus, their control in the environment is of utmost importance. Consumption or prescription data have demonstrated to be very valuable to estimate the presence of pharmaceuticals in environmental waters. This approach was first suggested by the European Medicines Agency (EMA) that proposed the calculation of predicted environmental concentration (PEC) based on consumption data, excretion, elimination in the WWTP, and dilution in receiving waters. Further, EMA recommended the evaluation of risk when PEC values in surface water were equal or above the threshold value of 0.01 µg/L. The calculation of PEC results is an extremely useful information to prioritize compounds for further monitoring, to establish the potential incidence of pharmaceuticals in a specific area, and even to assess their risk according to toxicological data. Cytostatic compounds account for an exemplary family to calculate the PECs, as differing from other pharmaceuticals, all the prescribed amounts will be consumed, and thus, PECs are very accurate. The objectives of this chapter are to define the concept of PECs, show how the calculations are undertaken in all its adaptations, provide the raw data for their calculation, and demonstrate its applicability for the assessment of cytostatics in wastewater and river water.