Exposure to Diesel Exhaust and Plasma Cortisol Response: A Randomized Double-Blind Crossover Study
- DOI
- Language of the publication
- English
- Date
- 2021-03-26
- Type
- Article
- Author(s)
- Thomson, Errol M.
- Filiatreault, Alain
- Williams, Andrew
- Rider, Christopher F.
- Carlsten, Chris
- Publisher
- National Institute of Environmental Health Sciences (NIEHS)
Abstract
Traffic-related air pollution (TRAP) is associated with a variety of adverse health effects. Although a central role has been proposed for oxidative stress, elucidating underlying mechanisms remains an area of active investigation. Experimental work has demonstrated that glucocorticoid stress hormones are potential mediators of pulmonary and systemic pollutant effects of both particulate and gaseous pollutants (Thomson 2019), but direct evidence of TRAP-dependent stress axis activation is lacking. Moreover, although oxidative stress is a regulator of glucocorticoid signaling (Okamoto et al. 1999), involvement in pollutant-induced stress axis activation is unknown. In population studies, nitrogen dioxide was associated with a flattened salivary cortisol profile in adolescents (Wing et al. 2018) and higher awakening cortisol and flattened profile in 45 to 85-y-old adults (Hajat et al. 2019), suggesting potential TRAP-related impacts. The present study evaluated whether short-term exposure to diesel exhaust increases plasma cortisol levels and considered effect modification by sex, asthma status, antioxidant gene variants, and antioxidant treatment.
Plain language summary
Health Canada conducts research to better understand the health impacts of air pollutants. Exposure to traffic-related air pollutants is linked to a variety of health impacts (e.g. cardiovascular disease, asthma, cognitive decline, dementia, depression, diabetes), but research efforts continue to explore how exposure to these pollutants results in such diverse health impacts. In the present study, Health Canada and University of British Columbia scientists evaluated whether short-term exposure to diesel exhaust increased blood levels of the stress hormone cortisol, and examined whether sex, asthma status, genetic variability, or antioxidants modified the effect. For the week prior to exposure, participants took an antioxidant pill or a placebo. On three separate days (minimum of two weeks between exposures), study participants entered an exposure chamber and breathed clean air or diluted diesel exhaust for 2 hours. Participants were not aware of which exposure they were experiencing. Breathing diesel exhaust increased blood cortisol levels. While effects were similar in males and females, they were driven by responses in people diagnosed with asthma, and those with variations in genes important for antioxidant response. Taking antioxidants prior to exposure reduced but did not eliminate the effect. Our results show that breathing diesel exhaust increases stress hormone levels, particularly in those with asthma. The study sheds light on a potential mechanism underlying health impacts of traffic-related air pollutants, and highlights how individual differences in our health and genes may contribute to vulnerability. Such information provides support to risk assessment and management exercises aimed at mitigating the adverse health impacts of air pollutants.
Subject
- Health,
- Health and safety