Degradation and elimination of anticancer drugs by water and wastewater treatment - toxicity and biodegradability before and after the treatment

Anticancer drugs are chemically spoken a broad group of pharmaceuticals especially designed to treat cancer. Many have been widely used for chemotherapy for decades. They are intrinsically toxic. After administration the active compound is excreted together with its metabolites because of incomplete mineralization in the human or animal body. Thereby they end up in hydrosphere and the pedosphere. In the hydrosphere they are present at the microgram per litre range or below. Therefore, they are part of the so-called micropollutants. During the last 20 years, researchers have focused their attention on the environmental fate of anticancer drugs as well as on the risks that these compounds may pose to humans and the environment. In general, these compounds are characterized by a poor environmental biodegradability and often they are not completely removed by conventional wastewater treatments. So called advanced oxidation processes (AOPs), i.e. additional oxidative treatment of wastewater treatment plant effluents has therefore been taken into consideration to solve the problem. Such processes are also used as a final treatment for the treatment of potable water. Among them is the treatment with UV light. Some advanced oxidation processes (AOPs) have been shown to eliminate pharmaceuticals in general at a high degree. However, often incomplete mineralization results in the formation of unwanted transformation products (TPs) of unknown chemical structure, toxicity and fate. In some cases, it was shown that TPs were easier to biodegrade compared to the parent compounds. Nevertheless, it was also found that many TPs are not biodegradable and are more toxic or exhibiting a different toxicity profile than the parent compounds. The present chapter provides an overview of different treatments used (chlorination, ozonation, photo treatment and other nonconventional treatments) to remove anticancer drugs from water (surface, distilled and ultrapure) and wastewater. It evaluates their efficiency based on the degrees of elimination, mineralization, biodegradation and toxicity of the parent compounds as well as possibly formed TPs.