Abstract:

Traditional phthalate esters （PAEs） and their novel alternatives are widely used as plasticizers. Owing to their non-covalent bonding with polymer matrices， these compounds readily migrate from materials and accumulate in indoor dust， posing potential risks to human health. Although their carcinogenic and reproductive toxicities have been extensively studied， their neurotoxicity， particularly that of novel alternatives， remains poorly understood. To address this knowledge gap， this study adopted an integrated approach combining pollution profiling， health risk assessment， and mechanistic investigation to systematically evaluate the neurotoxicity risks and potential mechanisms of PAEs and their alternatives in typical campus microenvironments （classrooms， laboratories， offices， cafeterias， and dormitories）. The contamination profile of target compounds in indoor dust was determined using comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry （GC×GC-TOF MS）. By integrating three exposure pathways （ingestion， inhalation， and dermal contact of dust） with absorption， distribution， metabolism， excretion， and toxicity （ADMET） models， the estimated daily intakes （EDIs） and neurotoxic health risks for different populations were assessed. Furthermore， network toxicology and molecular docking techniques were employed to elucidate the potential toxic mechanisms. Results indicated that dormitories exhibited the highest contents of target compounds， with major components including di-2-ethylhexyl phthalate （DEHP）， di（2-ethylhexyl） tetrahydrophthalate （DEHTH）， acetyl tri-n-butyl citrate （ATBC）， and trioctyl trimellitate （TOTM）. Exposure assessment identified ingestion as the predominant exposure route. Using the ADMET model， toxicity equivalency factor （TEF） and toxic equivalent quantity （TEQ） were quantified for five neurotoxicity-related health endpoints， including phenotypic neurotoxicity， estrogen receptor activity， oxidative stress， mitochondrial dysfunction， and DNA damage. Risk assessment based on TEQ revealed that females aged 18-60 years faced higher neurotoxicity risks than males， although no statistically significant gender differences in EDI were observed across all age groups. Mechanistically， network toxicology identified 59 core targets associated with neurotoxicity， including oncogene， non-receptor tyrosine kinase （SRC）， serine/threonine kinase 1 （AKT1）， estrogen receptor 1 （ESR1）， mitogen-activated protein kinase （MAPK1， MAPK3）， heat shock protein 90 alpha family class a member 1 （HSP90AA1）， and Kirsten rat sarcoma viral oncogene homolog （KRAS）. Functional enrichment analysis showed that these core targets were predominantly enriched in pathways related to endocrine resistance and cancer， suggesting that these compounds may induce neurotoxicity by disrupting cellular homeostasis and signal transduction. Molecular docking supported specific binding interactions between representative compounds and core proteins， validating the predicted associations. Notably， diphenyl phthalate （DPhP） and dicyclohexyl phthalate （DCHP） were identified as the key risk drivers. In contrast， novel alternatives with fewer aromatic rings and ester groups， such as diheptyl， N-nonyl adipate （DHeNoA）， diisobutyl adipate （DiBA）， and diisodecyl adipate （DiDeA）， exhibited lower neurotoxic potential. Structure-activity relationship analysis suggested that the synergistic effect of aromatic rings and ester groups is a critical mechanism inducing neurotoxicity. By integrating environmental exposure profiling， TEQ-based risk assessment， and molecular mechanism analysis， this study not only delineates the neurotoxicity risk profile for specific campus populations but also elucidates the influence of molecular structure on neurotoxicity， providing a scientific basis for the targeted screening of low-neurotoxicity alternatives and informed risk management of indoor environmental health.

Key words: phthalate esters, novel alternatives, indoor dust, occurrence characteristics, neurotoxicity risk, potential mechanisms