Residential Exposure To Traffic Pollution And Congenital Heart Defects, Preterm Births, And Low Birth Weight In Lanzhou, China

Introduction: Some studies have suggested an association of residence near major roads with adverse birth outcomes. However, little is known about this relationship in large Chinese cities, where intra-urban variation in traffic pollution is high due to crisscross major roads adjacent to residential areas. We investigated this relationship in Lanzhou, an important industrial city in China. Methods: To understand the dispersion patterns of traffic pollution, horizontal profile measurements of Nitrogen Dioxide (NO2) and Black Carbon (BC) were conducted within 200m of selected major roads. The study population is 8,558 pregnant women and their children recruited in a birth cohort study during 2010-2012. Residential exposure to traffic pollution was estimated by proximity to nearest major road, and total length of major roads within 200m of residence. The associations of the exposure metrics with Congenital Heart Defects (CHD), preterm births (PTB), and low birth weight (LBW) were estimated using logistic regression models adjusting for infant characteristics (e.g., gender), maternal demographics (age, education, income), health status and lifestyle choices (e.g., smoking, folate acid intake). Results: Concentrations of NO2 and BC decayed linearly by about 40% and 80% by 100m from the edge of a major road and reached a plateau. Compared to women residing far away from a major road (>500m), women residing closest to a major road (≤ 100m), and close to a major road (100-500m) are more likely to have infants with CHD [OR(≤100m): 3.8, 95%CI: 1.1, 13.8; OR(100-500m): 3.7, 95%CI: 1.1, 12.9], respectively. Positive associations between the three outcomes and total length of major roads near residence are consistent but marginally significant. Discussion: The results indicate potential risks of adverse birth outcomes associated with traffic pollution exposure. This work also calls for more research on this issue, and awareness of traffic control in residential area in China.