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Species of fine particulate matter and the risk of preterm birth
Citation:
Rappazzo, K., J. Daniels, L. Messer, C. Poole, AND D. Lobdell. Species of fine particulate matter and the risk of preterm birth. Presented at Society for Epidemiologic Research, Boston, MA, June 18 - 21, 2013.
Impact/Purpose:
Particulate matter (PM) has been variably associated with preterm birth (PTB), but the roles of PM species have been less studied. This study examined the role of PM species as an exposure and its association with PTB.
Description:
Particulate matter (PM) has been variably associated with preterm birth (PTB), but the roles of PM species have been less studied. We estimated risk of birth in 4 preterm categories (risks reported as PTBs per 106 pregnancies; PTB categories = gestational age of 20-27; 28-31; 32-34; and 35-36) and risk differences (RD(95% confidence intervals)) for PTB categories with change in ambient concentrations of species of PM <2.5 micrometers in aerodynamic diameter: a 0.25 μg/m3 increase in elemental carbon(EC), and 1 μg/m3 increases in organic carbons(OC) nitrates(NO3) and sulfates(SO4). From live birth certificates with clinical estimate of gestation and date of delivery, we constructed a 20-week gestational age cohort of singleton pregnancies between 2000-2005 (n=1,940,213; 8% PTB (approximately 80,000 per 106 for all categories)). We estimated mean EC, OC, NO3, and SO4 exposures for each week of gestation from monitor-corrected Community Multi-Scale Air Quality modeling data. RDs were estimated using modified Poisson linear regression, adjusted for maternal race, marital status, education, age, and ozone. RD estimates varied by exposure window and outcome period. EC was generally associated with increased risks for births between 28-34 weeks (e.g. a 0.25 μg/m3 increase in EC exposure at gestational week 5 RD=84(-5, 172) and RD=97(-50, 243) for birth at weeks 28-31 and 32-34, respectively). OC exposures in late gestation only were positively associated with births between 28-34 weeks. NO3 was not strongly associated with PTB. RDs for SO4 exposure in early and mid gestation were generally positively associated with PTB. Although potential for residual confounding exists, EC and SO4 appear to be influential contributors to of PM2.5’s role in PTB. These results indicate diverse periods of action for the species of PM, along with differing windows of vulnerability for the risk of various degrees of PTB. This abstract does not necessarily reflect EPA policy.