Integrated Toxicological, Network Toxicology, and Molecular Simulation Assessment of Inhalation Toxicity and Mechanisms of HFO-1336mzz(E) as an SF6 Alternative Insulating Gas

Abstract HFO-1336mzz(E) is a novel environmentally friendly insulating gas with a low global warming potential and favorable dielectric properties, and it has been regarded as an important potential substitute for sulfur hexafluoride (SF6). However, its systemic toxicological characteristics and underlying mechanisms under inhalation exposure remain insufficiently investigated. To address this issue, the present study, for the first time, systematically evaluated the biological safety of HFO-1336mzz(E) by integrating multilevel toxicological assessment with molecular mechanistic analysis. Acute inhalation toxicity, bone marrow micronucleus, and embryonic developmental toxicity experiments were conducted, and the potential toxic effects and mechanisms were comprehensively analyzed through the integration of molecular docking, functional enrichment analysis, and molecular dynamics simulations. The results showed that the 4-h LC50 of HFO-1336mzz(E) in both male and female rats was approximately 31,600 ppm, which is classified as Category 5 according to the Globally Harmonized System (GHS). Under high-dose exposure, the primary target organs were the lung and liver, characterized mainly by acute tissue responses dominated by congestion. Following low-to-moderate dose exposure, the physiological condition of the animals gradually recovered, and no extensive structural damage to tissues was observed. Under short-term inhalation exposure and repeated exposure during pregnancy, this compound did not induce significant genotoxicity, while only limited developmental toxicity effects were observed under the tested conditions. Further mechanistic analyses suggested that its potential toxic effects may involve disturbances in heme-dependent redox systems and energy metabolism pathways. These effects may be associated with the regulation of oxidative stress and inflammatory signaling pathways, which could subsequently influence local microcirculatory homeostasis and tissue perfusion status. This study systematically provides insights into the biological basis of the acute inhalation toxicity of HFO-1336mzz(E). Moreover, a multidimensional toxicological evaluation and mechanistic analysis framework for novel environmentally friendly insulating gases was established, providing important scientific support for risk assessment, safety standard formulation, and refined management in engineering applications.