EEG Neural Networks Reveal Influence of Indoor Toluene on Working Memory at Low Concentration

Toluene is a common domestic air contaminant and a neurotoxic volatile organic compound. However, few previous studies have directly evaluated the health effects of toluene exposure at a low concentration. This study conducted a within-subject experiment to compare working memory during delayed match-to-sample tasks with EEG recording under 0 ppb and 70 ppb toluene exposure. Compared with the the control group (Ctrl group, 0 ppb), power spectral density analysis showed that the alpha and theta bands in the frontal region of the toluene group (Tol group, 70 ppb) increased considerably in both the encoding and maintenance periods (P < 0.01 for theta, P < 0.05 for alpha). The direct transfer function indicated that the functional connectivity of the frontal network in the theta band (P < 0.01), gamma band (P < 0.01) and alpha band (P < 0.01) significantly decreased, while that of the frontoparietal network increased under toluene exposure in the theta (P < 0.01) and alpha bands (P < 0.01) during the maintenance period. Toluene exposure at the ppb level could cause differences in neural oscillation patterns and functional connectivity even in healthy subjects. Although there was no significant difference in task performance, we speculated that individual variations might be larger than changes caused by toluene.Funding: The Tianjin Natural Science Foundation Beijing-Tianjin-Hebei Special Project (18JCZDJC44800) and the National Natural Science Foundation of China (grant number 51978452) supported this project.Declaration of Interest: None to declare. Ethical Approval: The Ethical Review Board of Tianjin Medical University General Hospital, Tianjin, China, approved the experimental design.