Associations between Environmental Quality across Multiple Environmental Domains and Birth Weight

Abstract

Background: Exposure to environmental pollutants has been associated with both reduced birth weight (BW) through air pollutants and increased BW through endocrine disrupting chemicals. The impact of multiple environmental exposures across several domains in relation to changes in BW are not well understood.Methods: We constructed an environmental quality index at the census tract level (trEQI) to represent environmental quality across five domains (air, water, land, sociodemographic, and built) and overall for 2006-2010 using principal components analysis. The trEQI domains were categorized into quartiles (<25th, or best environmental quality and referent; 25th-50th; 50th-75th; >75th, or worst environmental quality) and linked to 735,507 mother-infant pairs in North Carolina (NC) with births between 2006-2011. Random intercept mixed effects linear regression models estimated the change in BW, in grams (g), presented as β estimate and 95% confidence intervals (CI), adjusted for maternal race/ethnicity, age, marital status, and medicaid status.Results: The worst environmental quality, or highest quartile, was associated with reduction in BW in the air [β: -10.41 g (95% CI: -17.06, -3.75)], water [β: -11.84 g (-18.82, -4.86)], and land [β: -9.17 g (-15.71, -2.65)] domains, compared to the best environmental quality. However, we observed increased BW in association with the sociodemographic [β: 34.82 g (28.44, 41.20)] domain and overall [β: 21.64 g (15.55, 27.73)] trEQI.Conclusions: With increasing interest in how environmental mixtures can influence health, this analysis uses a more spatially resolved exposure index than previously employed (i.e., census tract vs. county) and provides a broad view of how simultaneous environmental exposures across multiple domains can result in reduced or increased BW. This abstract does not reflect EPA policy.