Abstract
BackgroundChronic exposure to air pollutants is associated with increased risk of cardiovascular disease (CVD) among adults. However, little is known about how air pollution may affect the development of subclinical atherosclerosis in younger populations. Carotid artery intima-media thickness (CIMT) is a measure of subclinical atherosclerosis that provides insight into early CVD pathogenesis.MethodsIn a pilot study of 70 participants from the Southern California Children’s Health Study, we investigated CIMT progression from childhood to adulthood. Using carotid artery ultrasound images obtained at age 10 and follow-up images at age 21–22, we examined associations between childhood ambient and traffic-related air pollutants with changes in CIMT over time and attained adult CIMT using linear mixed-effects models adjusted for potential confounders.Average residential childhood exposures (i.e., birth to time of measurement at 10–11 years) were assigned for regional, ambient pollutants (ozone, nitrogen dioxide, particulate matter, interpolated from regulatory air monitoring data) and traffic-related nitrogen oxides (NOx) by road class (modeled using the CALINE4 line source dispersion model). Traffic density was calculated within a 300-m residential buffer.ResultsFor each 1 standard deviation (SD) increase in childhood traffic-related total NOx exposure, we observed greater yearly rate of change in CIMT from childhood to adulthood (β: 2.17 μm/yr, 95% CI: 0.78–3.56). Increases in annual rate of CIMT change from childhood to adulthood also were observed with freeway NOx exposure (β: 2.24 μm/yr, 95% CI: 0.84–3.63) and traffic density (β: 2.11 μm/yr, 95% CI: 0.79–3.43). Traffic exposures were also related to increases in attained CIMT in early adulthood. No associations of CIMT change or attained level were observed with ambient pollutants.ConclusionsOverall, we observed adverse changes in CIMT over time in relation to childhood traffic-related NOx exposure and traffic density in our study population. While these results must be cautiously interpreted given the limited sample size, the observed associations of traffic measures with CIMT suggest a need for future studies to more fully explore this relationship.
Highlights
Chronic exposure to air pollutants is associated with increased risk of cardiovascular disease (CVD) among adults
Our results suggest that childhood exposure to local traffic-related air pollution is associated with greater rate of yearly change in Carotid artery intima-media thickness (CIMT) from childhood to adulthood, as well as greater attained CIMT levels by age 21–22 with adjustment for adult body mass index (BMI) and personal smoking
We found that residential traffic density and exposure to traffic-related nitrogen oxides (NOx) in childhood were related to greater changes in CIMT over time
Summary
Chronic exposure to air pollutants is associated with increased risk of cardiovascular disease (CVD) among adults. Epidemiological and experimental studies have linked air pollutant exposures to multiple risk factors for CVD [20,21,22,23,24,25,26,27], including carotid artery intima media thickness (CIMT), a widely used measure of subclinical atherosclerosis [28, 29], and carotid arterial stiffness (CAS), a measure of endothelial function indicative of vascular health [30]. Two studies of long-term exposure to fine particulate matter (PM2.5) and traffic-related pollutants found associations with accelerated progression of atherosclerosis, as measured by increases in CIMT over time [32, 35] Together, these studies provide a strong body of evidence supporting a role for ambient and traffic-related air pollutants in the development of CVD by promoting atherosclerosis, the key underlying pathological process that leads to clinical cardiovascular events
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