Metabolic profiles of nighttime road traffic noise exposure: A multi-cohort study in the European LongITools project

BACKGROUND: Traffic noise has been associated with the risk of cardiometabolic diseases. Identifying internal exposome factors, such as metabolomic biomarkers, associated with traffic noise in the general population may help clarify the pathophysiological pathways linking noise to cardiometabolic outcomes. To address this gap, we investigated the relationships between nighttime road traffic noise and systemic metabolic biomarkers. METHODS: This study included 272,229 European adults, aged 31 years and over, from the UK Biobank (UKBB), the Rotterdam Study (RS), and the Northern Finland Birth Cohort 1966 (NFBC1966). Annual average nighttime road traffic noise was linked to the individual residential address at the time of blood sampling, using national noise maps. We utilized high-throughput nuclear magnetic resonance metabolomics to profile 155 biomarkers (including lipids, lipoproteins, fatty acids, and other low-molecular-weight metabolites). In discovery analyses in UKBB, we applied linear models adjusted for age, sex, education, and fine particulate matter to identify significant biomarkers (Bonferroni P < 0.003125). The associated biomarkers were further assessed using multilevel random-effects meta-analysis across the UKBB, RS, and NFBC1966. RESULTS: From the discovery analysis, nighttime road traffic noise (≥55 dB versus