Airborne PM_2.5 Chemical Components and Low Birth Weight in the Northeastern and Mid-Atlantic Regions of the United States

Keita Ebisu and Michelle L. Bell

School of Forestry and Environmental Studies, Yale University, New Haven, Connecticut, USA

Abstract

Background: Previous studies on air pollutants and birth outcomes have reported inconsistent results. Chemical components of particulate matter ≤ 2.5 μm (PM_2.5) composition are spatially heterogeneous, which might contribute to discrepancies across PM_2.5 studies.

Objectives: We explored whether birth weight at term is affected by PM_2.5, PM₁₀ (PM ≤ 10 µm), and gaseous pollutants.

Methods: We calculated exposures during gestation and each trimester for PM_2.5 chemical components, PM₁₀, PM_2.5, carbon monoxide, nitrogen dioxide, ozone, and sulfur dioxide for births in 2000–2007 for states in the northeastern and mid-Atlantic United States. Associations between exposures and risk of low birth weight (LBW) were adjusted by family and individual characteristics and region. Interaction terms were used to investigate whether risk differs by race or sex.

Results: Several PM_2.5 chemical components were associated with LBW. Risk increased 4.9% (95% CI: 3.4, 6.5%), 4.7% (3.2, 6.2%), 5.7% (2.7, 8.8%), and 5.0% (3.1, 7.0%) per interquartile range increase of PM_2.5 aluminum, elemental carbon, nickel, and titanium, respectively. Other PM_2.5 chemical components and gaseous pollutants showed associations, but were not statistically significant in multipollutant models. The trimester associated with the highest relative risk differed among pollutants. Effect estimates for PM_2.5 elemental carbon and nickel were higher for infants of white mothers than for those of African-American mothers, and for males than females.

Conclusions: Most exposure levels in our study area were in compliance with U.S. Environmental Protection Agency air pollution standards; however, we identified associations between PM_2.5 components and LBW. Findings suggest that some PM_2.5 components may be more harmful than others, and that some groups may be particularly susceptible.

Key words: air pollution, environmental health, epidemiology, low birth weight. 

Environ Health Perspect 120:1746–1752 (2012). http://dx.doi.org/10.1289/ehp.1104763 [Online 20 September 2012]

Address correspondence to K. Ebisu, Yale University, School of Forestry and Environmental Studies, New Haven, CT 06511 USA. Telephone: (203) 432-9869. Fax: (203) 436 9158. E-mail: keita.ebisu@aya.yale.edu

Supplemental Material is available online (http://dx.doi.org/10.1289/ehp.1104763).

We thank K. Belanger, Yale Center for Perinatal, Pediatric and Environmental Epidemiology.

This work was supported by the U.S. Environmental Protection Agency (RD 83479801) and the National Institute of Environmental Health Sciences (R01ES016317, R01ES019560, R01ES019587, and R01ES015028).

The authors declare they have no actual or potential competing interests.

Received 18 November 2011; Accepted 20 September 2012; Online 20 September 2012.