The Association between Long-Term Air Pollution and Urinary Catecholamines: Evidence from the Multi-Ethnic Study of Atherosclerosis

BACKGROUND: Autonomic nervous system effects have been hypothesized as a mechanism of air pollutant health effects, though scant prior epidemiologic research has examined the association between air pollutants and catecholamines. OBJECTIVES: To examine the association of long-term air pollutants with three urinary catecholamines: dopamine (DA), epinephrine (EPI), and nor epinephrine (NE). As a secondary aim, we also examined the association between short-term (or acute) exposure to fine particulate matter [particulate matter with aerodynamic diameter <= 2.5 mu m (PM2.5)] and those catecholamines. METHODS: We used data from the Multi-Ethnic Study of Atherosclerosis (MESA) and two of its ancillary studies, the MESA Air Pollution Study and the MESA Stress Study, to provide exposure and outcome data. DA, EFL and NE from urine samples were collected from 2004 to 2006 from 1,002 participants in the New York, New York, and Los Angeles, California, study sites. Spatimemporal models incorporated cohort-specific monitoring and estimated annual average pollutant concentrations (PM2.5, NO2, NOx, and black carbon) at participants' homes thc year prior to urine collection. Secondarily, short-term PM2.5 was evaluated (day of, day prior, and 2-to 5-cl lags prior to urine collection). Several covariates were considered confounders (age, race, scx, site, socioeconomic status, cardiovascular disease risk factors, psychosocial stressors, and medication use) in linear regression models. RESULTS: A 17 ppb higher annual NOx concentration was associated with 6.3% higher mean EPI level [95% confidence interval (CI): 0.3%, 12.6%]. A 2-mu g/m(3) higher annual ambient PM2.5 concentration was associated with 9.1% higher mean EPI (95% CI: 3.2%, 15.3%) and 4.4% higher DA level (95% Cl: 1%, 7.9%). NO2, black carbon, and short-term PM2.5 exposures were not significantly associated with any of the catecholamines. CONCLUSIONS: We found an association between EPI and long-term concentrations of PM2.5 and NO, and an association between DA and long-term ambient PM2.5. These novel findings provide modest support for the hypothesis that air pollutant exposures are related to sympathetic nervous system activation.