Gestational Exposure to Urban Air Pollution Related to a Decrease in Cord Blood Vitamin D Levels

Context: Vitamin D deficiency has been implicated in the increased risk of several diseases. Exposure to air pollution has been suggested as a contributor to vitamin D deficiency. However, studies that have examined the effects of air pollution on vitamin D status are few and have never focused on prenatal life as an exposure window. Objective: Our aim was to investigate the associations between gestational exposure to urban air pollutants and 25-hydroxyvitamin D [25(OH)D] cord blood serum level in 375 mother-child pairs of the EDEN birth cohort. Design: The Atmospheric Dispersion Modelling System (ADMS-Urban) pollution model, a validated dispersion model combining data on traffic conditions, topography, meteorology, and background pollution, was used to assess the concentrations of two major urban pollutants, particulate matter less than 10 mu m in diameter (PM10) and nitrogen dioxide (NO2), at the mother's home address during pregnancy. Cord blood samples were collected at birth and were analyzed for levels of 25(OH) D. Results: Maternal exposure to ambient urban levels of NO2 and PM10 during the whole pregnancy was a strong predictor of low vitamin D status in newborns. After adjustment, log-transformed 25(OH) D decreased by 0.15 U (P = 0.05) and 0.41 U (P = 0.04) for a 10-mu g/m(3) increase in NO2 and PM10 pregnancy levels, respectively. The association was strongest for third-trimester exposures (P = 0.0003 and P = 0.004 for NO2 and PM10, respectively). Conclusion: Gestational exposure to ambient urban air pollution, especially during late pregnancy, may contribute to lower vitamin D levels in offspring. This could affect the child's risk of developing diseases later in life. (J Clin Endocrinol Metab 97: 4087-4095, 2012)