Low birth weight and exposure to particles and ozone in Los Angeles County, California

摘要

Background Low birth weight (LBW, ＜2,500 g) is often associated with exposure to particles of coarse (PM10) and fine (PM2.5) size fractions, but their association with ultrafine particles (PM0.1) has seldom been studied. Beside, It is unclear which sources of particles increase the risk of LBW. Studies of ozone (O3) and LBW have reported mixed results. Aims To study the relationships between LBW in term born infants (＞37 weeks gestation) and exposure to particles and ozone in Los Angeles County (California, USA) over period 2001-2006. Methods Primary particulate matter concentrations were modeled at a 4 km*4 km grid resolution, by emission source (high sulfur fuel, diesel, gasoline, wood, cooking, shipping and others), for PM10, PM2.5 and PM0.1. Ambient total PM2.5 and O3 concentrations measured by monitoring stations were interpolated using empirical Bayesian kriging. Birth certificates (n= 726,871) with maternal addresses at delivery were geocoded to parcel level whenever feasible. The associations between LBW and air pollutants concentrations averaged over the whole pregnancy were examined using generalized additive models, adjusting for maternal age, parity, race/ethnicity, education, neighborhood income, gestational age and infant sex. Results In preliminary analyses, LBW (n=17,169) is positively associated with exposure to PM10, PM2.5 and PM0.1 emitted by food cooking and gasoline sources. Marginally significant associations are also observed for total primary PM2.5 (p=0.06) and PM0.1 (p=0.05). No significant association is observed with interpolated total PM2.5 or O3. Conclusions These preliminary results suggest that the risk of LBW is positively associated with exposure to total primary PM2.5 and PM0.1,and with primary PM10, PM2.5 and PM0.1 emitted by food cooking and gasoline. Further analyses are underway to assess the robustness of these findings.