Examination of the Degradation of the Antineoplastic Drug 5-Fluorouracil by Chlorine at Varying Treatment Conditions

Abstract

Trace-level organic contaminants that belong to the group of chemotherapeutic (antineoplastic) drugs have been detected in municipal wastewaters and, at lower concentrations, surface waters. The presence of even trace levels of these compounds is of concern due to their inherently high toxicity and low biodegradability. In this study, we examined effects of chlorine concentrations, pH and other reaction conditions such as reaction time, ionic strength, and concentrations of bromide and chloride on the removal of 5 &ndash fluorouracil (5 &ndash FU). The experimental procedure was primarily based on the spectrophotometric determination of 5&ndashFU concentrations. The data were processed to obtain pseudo first-order reaction rates of the removal of 5&ndashFU. Apparent rates of 5&ndashFU removal were strongly pH&ndashdependent reaching a maximum at a pH close to 7.3. Variation of bromide and chloride levels resulted in strong changes of pH-dependent apparent kinetic rates. The obtained data allowed estimating half-times of 5&ndashFU in chlorinated water. For a typical chlorine concentration of 1 mg/L, and in the absence of bromide, 50% of 5&ndashFU can be removed within ca. one hour of exposure at pH close to 7.3. The half time decreases rapidly in the presence of even trace levels of bromide. The obtained results show that water treatment conditions play a critical role in the removal of 5&ndashFU and other trace-level antineoplastic agents that may be present in wastewater and drinking water supplies.