Cytostatic Drug Residues in Wastewater Treatment Plants: Sources, Removal Efficiencies and Current Challenges

Abstract

The discharge of pharmaceutical compounds present in wastewater into the aquatic environment has been a source of discussion and concern in scientific and regulatory communities for the last decades. However, cytostatic drugs used in chemotherapy have received less attention than other pharmaceuticals, despite the fact that they may possess cytotoxic, genotoxic, mutagenic, carcinogenic, endocrine-disrupting, and/or teratogenic effects toward several organisms. Hospital wastewater effluents are the major source of cytostatic drugs, while also urban wastewater effluents receive a substantial contribution of excreted drugs as the result of outpatient’s treatment. Their removal efficiency during wastewater treatment processes has been found to vary significantly, depending both on the compounds’ physicochemical properties and on the treatment process applied. In general, biological processes do not achieve high removal efficiencies for these compounds, since many of them are poorly biodegradable. Consequently, they are continuously released into the aquatic and terrestrial environment at trace levels. However, there is still a lack of knowledge regarding both their presence in the natural environment – which depends on consumption patterns, the excretion fraction, and the effectiveness of the wastewater treatment – and the possible risks to humans and to the environment, requiring further investigation toward this direction. The aim of this chapter is to thoroughly review the removal efficiencies and mechanisms of cytostatic drugs in wastewater treatment plants, as well as what is required for future research, in view of the current concerns related to the induction of toxic effects in aquatic and terrestrial organisms by these compounds.