Road traffic noise and saliva cortisol levels in adolescents

Abstract

Introduction: Long term exposure to traffic noise is associated with an increased risk of cardiovascular diseases and possibly also metabolic diseases. Stress-related mechanisms could be of importance, which might be monitored by cortisol. We analysed levels of saliva cortisol in relation to residential road traffic noise exposure among adolescents. Methods: Using a radioimmunoassay technique, we measured morning and evening saliva cortisol levels in samples of 646 adolescents (mean age=16.5 years) in the BAMSE birth cohort. For each individual, we assessed exposure to residential road-traffic noise during life-time using a newly developed methodology which has been extensively validated. All individuals responded to an extensive questionnaire, also assessing levels of annoyance to noise from traffic. Linear regression was used to analyse associations between residential road traffic noise exposure and saliva cortisol levels. Results: We observed higher morning saliva cortisol levels in females than in males, with geometric means of 42.3 nmol/l and 33.4 nmol/l, respectively (p<0.001). There was no clear association between traffic noise exposure at home and saliva cortisol levels. More females than males were annoyed by road traffic close to their homes (21 vs 14 %) and significant associations were observed between annoyance to traffic noise and morning saliva cortisol levels.