Unveiling Phase-Dependent Genotoxicity of Organic Pollutants in Gaseous and Aqueous Forms

Organic pollutants exist in various physical states within the natural environment, yet it remains unclear how their physical states influence their toxicity characteristics. This study investigated the phase-dependent genotoxicity and combined effects of two organic compounds, tert-butyl hydroperoxide (TBHP) and dimethyl sulfate (DES), in both gaseous and aqueous phases. Given the substantial differences in concentrations for the same compound in gaseous and aqueous environments, we constructed the complete multitoxic and dose-response curves for gene induction in both phases, covering environmentally relevant concentrations. Under the same stress conditions, the genotoxicity of gaseous TBHP was 158.21 ± 33.17% of that of its aqueous form, while gaseous DES exhibited 260.56 ± 12.63% of the genotoxicity of its aqueous form. Notably, while no formation of new reaction products were observed, aqueous-phase mixtures exhibited greater complexity and higher toxicity compared to their gaseous counterparts. These differences were attributed to variations in molecular energy states, free radical generation and diffusion, molecular interaction pathways, and chemical reactivity between the two phases. By elucidating the mechanisms underlying these disparities, this study highlights the critical role of physical states in evaluating the toxicity and risks associated with gaseous organic chemicals.