Exposure to emerging water contaminants and human health risk: Cytotoxic and genotoxic effects of caffeine and diethyltoluamide (DEET) on eukaryotic cells

Abstract

The presence of emerging pollutants in aquatic ecosystems due to human activities poses substantial concerns. While many studies explore detection and removal techniques for these compounds, conventional treatment methods often fail to address emerging pollutants. Moreover, there is a lack of legislation defining safe thresholds for these substances in water. Consequently, caffeine and N,N-diethyl-meta-toluamide (DEET) persist in surface waters, including treated sources, with limited understanding of their genomic effects on human cells. This study aimed to assess the cytotoxic and genotoxic effects of caffeine and DEET, individually and in combination, at concentrations detected in drinking water, using HepG2 cells. Additionally, through systems biology, we sought to understand the underlying molecular mechanisms of both substances. Cytotoxicity was evaluated using MTT and Trypan Blue assays, while genotoxicity was assessed using the comet assay. The chemoproteomic interaction network was constructed using STITCH and STRING databases, with subnetworks analyzed using Cytoscape plugins (MCODE, CentiScaPe, and BiNGO). Both compounds reduced HepG2 cell viability in a dose-dependent manner in both assays. Caffeine and DEET also induced DNA damage at all tested concentrations, including in co-exposure. Proteins related to the inflammatory response, signaling pathways, and xenobiotic metabolism were the main hub-bottlenecks of the chemoproteomic interaction network. These findings underscore the urgent need for further investigations into the presence of emerging pollutants in drinking water and their potential risks to human health.