Association between GIS-based exposure to urban air pollution during pregnancy and birth weight in the INMA Sabadell Cohort.
BACKGROUND
There is growing evidence that traffic-related air pollution reduces birth weight. Improving exposure assessment is a key issue to advance in this research area.


OBJECTIVE
We investigated the effect of prenatal exposure to traffic-related air pollution via geographic information system (GIS) models on birth weight in 570 newborns from the INMA (Environment and Childhood) Sabadell cohort.


METHODS
We estimated pregnancy and trimester-specific exposures to nitrogen dioxide and aromatic hydrocarbons [benzene, toluene, ethylbenzene, m/p-xylene, and o-xylene (BTEX)] by using temporally adjusted land-use regression (LUR) models. We built models for NO(2) and BTEX using four and three 1-week measurement campaigns, respectively, at 57 locations. We assessed the relationship between prenatal air pollution exposure and birth weight with linear regression models. We performed sensitivity analyses considering time spent at home and time spent in nonresidential outdoor environments during pregnancy.


RESULTS
In the overall cohort, neither NO(2) nor BTEX exposure was significantly associated with birth weight in any of the exposure periods. When considering only women who spent < 2 hr/day in nonresidential outdoor environments, the estimated reductions in birth weight associated with an interquartile range increase in BTEX exposure levels were 77 g [95% confidence interval (CI), 7-146 g] and 102 g (95% CI, 28-176 g) for exposures during the whole pregnancy and the second trimester, respectively. The effects of NO(2) exposure were less clear in this subset.


CONCLUSIONS
The association of BTEX with reduced birth weight underscores the negative role of vehicle exhaust pollutants in reproductive health. Time-activity patterns during pregnancy complement GIS-based models in exposure assessment.
Aguilera
Inmaculada
I
Centre for Research in Environmental Epidemiology, Barcelona, Spain. iaguilera@creal.cat
Guxens
Mònica
M
Garcia-Esteban
Raquel
R
Corbella
Teresa
T
Nieuwenhuijsen
Mark J
MJ
Foradada
Carles M
CM
Sunyer
Jordi
J
D000293:Adolescent; D000328:Adult; D000393:Air Pollutants / Q000633:toxicity*; D001554:Benzene / Q000633:toxicity; D001555:Benzene Derivatives / Q000633:toxicity; D001724:Birth Weight / Q000187:drug effects*; D004781:Environmental Exposure; D005260:Female; D040362:Geographic Information Systems; D006801:Humans; D007231:Infant, Newborn; D016014:Linear Models; D008297:Male; D018811:Maternal Exposure; D011247:Pregnancy; D011264:Pregnancy Trimesters; D014050:Toluene / Q000633:toxicity; D014505:Urban Population / Q000706:statistics & numerical data; D014992:Xylenes / Q000633:toxicity; D055815:Young Adult
D000393:Air Pollutants; D001555:Benzene Derivatives; D014992:Xylenes; D014050:Toluene; D001554:Benzene; C004912:ethylbenzene