Prenatal exposure to fine particulate matter and birth weight variations by particulate constituents and sources

Abstract

Background: Exposure to fine particles (PM(2.5)) during pregnancy has been linked to lower birth weight; however, the chemical composition of PM(2.5) varies widely. The health effects of PM(2.5) constituents are unknown.

Methods: We investigated whether PM(2.5) mass, constituents, and sources are associated with birth weight for term births. PM(2.5) filters collected in 3 Connecticut counties and 1 Massachusetts county from August 2000 through February 2004 were analyzed for more than 50 elements. Source apportionment was used to estimate daily contributions of PM(2.5) sources, including traffic, road dust/crustal, oil combustion, salt, and regional (sulfur) sources. Gestational and trimester exposure to PM(2.5) mass, constituents, and source contributions were examined in relation to birth weight and risk of small-at-term birth (term birth <2500 g) for 76,788 infants.

Results: Road dust and related constituents such as silicon and aluminum were associated with lower birth weight, as were the motor-vehicle-related species such as elemental carbon and zinc, and the oil-combustion-associated elements vanadium and nickel. An interquartile range increase in exposure was associated with low birthweight for zinc (12% increase in risk), elemental carbon (13%), silicon (10%), aluminum (11%), vanadium (8%), and nickel (11%). Analysis by trimester showed effects of third-trimester exposure to elemental carbon, nickel, vanadium, and oil-combustion PM(2.5).

Conclusions: Exposures of pregnant women to higher levels of certain PM(2.5) chemical constituents originating from specific sources are associated with lower birth weight.