Abstract 3436: Exposure to long-term traffic-related air pollutants, NO2 and NOX, and breast cancer incidence: The Multiethnic Cohort

Introduction: California has one of the highest levels of air pollution in the nation. Vehicle exhaust contains a mixture of gases and particulate matter that are known to have mutagenic and carcinogenic effects. Our objective was to examine the effects of markers of traffic-related air pollutants on breast cancer risk among the California component of Multiethnic Cohort (MEC). Methods: Residential addresses from baseline, 1993-1996, through 2010 for over 57,000 female California MEC participants were geocoded to latitude and longitude coordinates and used to estimate traffic-related air pollutant exposures of NO2 and NOX, using three complementary approaches: 1) land use regression (LUR) models based on passive diffusion measurements, land use patterns, roadway and traffic data, and satellite information (high spatial but low temporal resolution); 2) Bayesian kriging interpolation of state and national government air monitoring data (low spatial but high temporal resolution); 3) California line source dispersion model, version 4 (CALINE4) based on local traffic emissions, traffic volume, roadway geometry, meteorological conditions (high spatial and moderate temporal resolution). A total of 2,639 incident breast cancer cases (315 Japanese Americans, 830 Latinas, 974 African Americans and 511 whites) were identified by linkage to the California cancer registry. Cox proportional hazard regression was conducted to examine the long-term effects of NO2 and NOX (annual average exposure for up to 18 years), adjusting for age, race/ethnicity, education, health behaviors, established breast cancer risk factors, and neighborhood SES. Results: For NO2, per unit (ppb) increase in the interquartile range, a non-statistically significant association with breast cancer risk was observed with the LUR model among all women (OR = 1.04; 95% CI: 0.99-1.09). A significant positive association was seen in Japanese Americans (OR = 1.20; 95% CI: 1.07-1.34; p = 0.002) that met a conservative Bonferonni significance threshold (p = 0.003), but no associations were seen in African Americans, Latinas, and Whites. For NOx, per unit (ppb) increase in the interquartile range, no significant increased risk of breast cancer was seen with the CALINE4 model among all women, but a positive association was seen in Japanese Americans (OR = 1.10, 95% CI: 1.02-1.19; p = 0.016). NO2 and NOx exposures based on the kriging model were not associated with breast cancer risk among all women or in speci