Prenatal Air Pollution and Newborns' Predisposition to Accelerated Biological Aging EDITORIAL COMMENT

Abstract

Telomere length (TL) is considered amolecular marker of biological aging. Telomeres shorten with each cellular division, and their length is associated with age-related diseases, lifestyle factors such as smoking, and environmental factors that influence the oxidative stress and inflammatory status in humans. Airborne particulate matter (PM) was ranked as the sixth leading risk factor influencing public health worldwide in 2015 by the Global Burden of Disease Study and is proposed to exert its adverse mechanism on human health through reactive oxygen species and inflammation. Long-term exposure to PMhas been associated with decreased TL in adults. However, little is known about the association between prenatal PM exposure and TL at birth. This prospective cohort study aimed to elucidate the association between maternal PM2.5 (particles with aerodynamic diameter <= 2.5 mu m) exposure and TL at birth. Mothers with a singleton, full-term birth were recruited in Flanders, Belgium, between February 2010 and December 2014. Fetal DNAwas extracted from participant's cord blood leukocytes and placental tissue, and quantitative, real-time polymerase chain reactionwas used to calculatemean relative TL. The PM2.5 exposure metric was calculated based on daily PM2.5 concentrations estimated using the mother's home address and a high-resolution spatial-temporal interpolation method (kriging) in combination with a dispersion model. Distributed lag models were used for the association between log10-transformed TL and mean PM2.5 exposures during gestational weeks 1 to 40. Association data were controlled for a priori covariates such as date of delivery, gestational age, maternal body mass index and age, paternal age, sex, ethnicity, parity, maternal education and smoking status, and pregnancy complications. A total of 641 participants were recruited with a mean gestational age of 39.4weeks, a mean maternal age of 29.1 years, and mean relative newborn TL ranging from 0.51 to 1.75 in cord blood and 0.52 to 1.89 for placental tissue. The data showed a nonlinear dose-response correlation. Telomere length from both cord blood and placenta was inversely associated with PM2.5 exposure during midgestation (weeks 12-25 for cord blood, weeks 15-27 for placenta), with the largest negative associations occurring in weeks 19 and 21 for cord blood and placental tissue, respectively. The calculated change in TL (overall, weeks 1-40) for a 5-mu g/m(3) increment in PM2.5 exposure was -8.8% (95% confidence interval, -14.1 to -3.1%) for cord blood and -13.2% (95% confidence interval, -19.3% to -6.7%) for placenta. Cord blood leukocyte and placental TL was negatively associated with PM2.5 exposure throughout the pregnancy and specifically during the second trimester. It is in this phase of fetal development that the maternal-fetal circulatory systembecomes more metabolically active.