Health Impacts of PM Emissions from Brake Pad Wear: A Comprehensive Study on Pulmonary, Metabolic, and Microbiota Alterations.

The environmental impact of harmful particles from tire and brake systems is a growing concern. This study investigated the health impacts of PM emissions from brake pad wear on adult C57BL/6 mice. The mice were exposed to brake pad particles via intratracheal infusion, and various health parameters were assessed. The results showed that brake pad particle exposure significantly reduced lung function parameters such as tidal volume, peak expiratory time ratio, and peak inspiratory flow rate, while increasing the apnea index and airway stenosis index. Histological analysis revealed particle deposition, inflammatory damage, and potential fibrosis in the lungs. Additionally, inflammatory markers and fibrosis indicators were elevated in the lung tissue. Metabolomic analysis indicated changes in metabolites related to purine metabolism, protein digestion, nucleic acid metabolism, and pathways involving Caffeine, Xanthine, Inosine, and others. Gut microbiota analysis showed increased abundance of Odoribacter and Tuzzerella, and decreased abundance of Desulfovibrio and Butyricimonas. Correlation analysis further suggested a significant link between the abundance of Odoribacter and plasma metabolic changes. Overall, this study underscores the health risks associated with brake dust pollution, particularly its adverse effects on lung function and induction of lung damage and fibrosis.