Assessing the human risk and the environmental fate of pharmaceutical Tramadol

Abstract Tramadol is a widely used human pharmaceutical and a well-established emerging pollutant and its potential genotoxic and cytotoxic effects on humans as well as its fate in aqueous systems demand full investigation. The present study is a multidisciplinary approach and provides important insights on the potential risks of Tramadol on humans accompanied by its photolytic transformation under simulated solar irradiation. The present study revealed that Tramadol can induce genotoxic and cytotoxic effects under the specific experimental conditions, significantly depended on the tested concentration. In addition, the photolytic transformation of Tramadol was investigated in detail under simulated solar irradiation in two different water matrices: ultrapure water (UW) and treated wastewater (WW). Differences in the degradation rates were observed between UW and WW, being slower in WW. The results showed that more than 70 % of TRA was removed after 240 min in UW ([TRA]=10 mg L-1, I=500 W m-2). After this period, TOC removal was found to be about 40%. Transformation of N atoms into NO3- and NH4+ followed a similar trend reaching up to 38% release. Τramadol degraded mainly by HO• radicals and 1O2 through a self-sensitizing process while direct photolysis was also significant. Hydroxylation, demethylation and N-oxidation of the parent compound were found to be the main degradation pathways confirming the important role of HO• and 1O2 in the photolytic process. Toxicity measurements showed a noticeable increase of the inhibition for Vibrio fischeri at the first stages which coincide with the formation of the major TPs.