In silico environmental risk assessment of fate and effects of pharmaceuticals and their TPs generated and treated by coupling tertiary processes in hospital wastewater

Abstract

The solar photo-Fenton process leads to the formation of transformation products (TPs) that are new compounds with an unknown chemical, physical, and biological characteristics. There are no commercial analytical standards for these new TPs. Due to this difficulty, ecotoxicity studies have been able to provide only limited information, while intrinsic features of the samples (such as complexity and matrix effects), as well as issues related to the sensitivity of the test organism, can further hinder investigations in cases where TPs coexist in mixtures. However, a viable option is to carry out in silico studies that do not use analytical standards or living organisms and do not require long testing periods to reach endpoints. In the present work, 90 chemical compounds (pharmaceuticals and their TPs generated by the solar photo-Fenton process) were evaluated using freely available software to assess the following endpoints: biodegradability, carcinogenicity, mutagenicity, and PBT (persistence, bioaccumulation, and toxicity). Chemometric analyses (HCA and PCA) were also applied to enhance the interpretation of the results. The main findings were that flutamide, chloramphenicol, and nimesulide, together with their TPs, were mostly non-biodegradable compounds that could be potentially mutagenic and carcinogenic. Therefore, these drugs and their TPs should not be released into the environment. The results indicated that it could be important to improve the solar photo-Fenton process or to couple this Advanced Oxidation Process with additional physicochemical treatment in order to efficiently remove these organic microcontaminants.