ATS 2013, PHILADELPHIA ─ Living near a major roadway during the prenatal period is associated with an increased risk of respiratory infection developing in children by the age of 3, according to a new study from researchers in Boston.
"The connection between in utero and early life cigarette smoke exposure and adverse infant respiratory outcomes is well-established, but the relation of prenatal ambient air pollution to risk of infant respiratory infection is less well-studied," said lead author Mary Rice, MD, a pulmonary and critical care fellow at Massachusetts General Hospital and Beth Israel Deaconess Medical Center. "Our study extends previous findings by showing that proximity to a major roadway during the prenatal period is associated with increased risk of subsequent respiratory infection in children."
The study results will be presented at the ATS 2013 International Conference in Philadelphia.
The study included 1,271 mother-child pairs enrolled during the first trimester of pregnancy between 1999 and 2002 in Project Viva in eastern Massachusetts. The distance from home addresses to the nearest Federal class 1/2A ("major") roadway was calculated using geographic information system software. Respiratory infections were defined as maternal report of any doctor-diagnosed pneumonia, bronchiolitis, croup or other respiratory infection from birth until age 3.
Statistical analyses of the relationship between exposure to a major roadway and respiratory infection were adjusted for gender, birth weight, maternal education, household income, neighborhood income and education, maternal smoking during pregnancy, postnatal household smoking, breastfeeding, daycare attendance, presence of other young children in the household and season of birth.
Of the 1,271 mother-child pairs studied, 6.4% lived less than 100 meters, 6.5% lived 100 to 200 meters, 33.7% lived 200 to less than 1000 meters and 53.4% lived 1,000 meters or more from a major roadway.
By the age of 3, 678 (53.3%) of the children had had at least one doctor-diagnosed respiratory infection. After adjustment for possible confounders and risk factors for respiratory infection, children whose mothers lived less than 100 meters from a major roadway during pregnancy were 1.74 times as likely as those living 100 meters or more from a major roadway to have had a respiratory infection. Those living 100 to 200 meters from a major roadway were1.49 times as likely to have had a respiratory infection.
"In our study, living in close proximity to a major roadway during pregnancy was associated with an increased risk of respiratory infection in children, adding to the growing body of evidence linking exposure to traffic with adverse effects on health," said Dr. Rice. "Future research will need to clarify whether the apparent harmful postnatal effects of living close to a major road during pregnancy is due to air pollution from traffic or other exposures related to roads. We plan to further explore this connection using a measure of black carbon, a component of traffic-related air pollution. Using black carbon measures, we also plan to disentangle the associations of pre- vs postnatal air pollution exposures with respiratory infection in early life."
* Please note that numbers in this release may differ slightly from those in the abstract. Many of these investigations are ongoing; the release represents the most up-to-date data available at press time.
Exposure To Traffic And Early Life Respiratory Infection: A Cohort Study
Type: Scientific Abstract
Category: 06.01 - Air Pollution: Epidemiology and Mechanisms (EOH)
Authors: M.B. Rice1, S. Rifas-Shiman2, A.A. Litonjua3, E. Oken2, M.W. Gillman2, M.A. Mittleman4, D. Gold3; 1Massachusetts General Hospital - Boston, MA/US, 2Harvard Medical School/Harvard Pilgrim Health Care Institute - Boston/US, 3Brigham and Women's Hospital - Boston, MA/US, 4Beth Israel Deaconess Medical Center - Boston/US
RATIONALE: Case-control and emergency room visit studies suggest that exposure to traffic-related pollutants may increase risk of early life respiratory infection. Using geographic information system (GIS) software to estimate distance from home to the nearest major roadway, we examined whether proximity to a major roadway, a surrogate for traffic-related pollution exposure, increases risk of respiratory infection by age 3 in a pre-birth cohort in the Boston area.
METHODS: We geocoded addresses for each of 1271 mother-child pairs enrolled during the first trimester of pregnancy in Project Viva during 1999-2002. We calculated distance from home address to nearest Federal class 1/2A ("major") roadway by GIS. We defined respiratory infection as maternal report of any doctor-diagnosed pneumonia, bronchiolitis, croup or other respiratory infection from birth to age 3. We used logistic regression models to estimate the association between distance to roadway and odds of respiratory infection comparing 4 exposure categories selected on the basis of prior studies (<100m, 100 to <200m, 200 to <1000m, and >1000 m from a major roadway). To assess trends, we assigned each exposure category the natural log of the median distance to roadway within that category.
RESULTS: Of the 1271 mother-child pairs, 88 (6.4%) lived <100m, 90 (6.5%) lived 100 to <200m, 464 (33.7%) lived 200 to <1000m and 735 (53.4%) lived >1000m from a major roadway. By age 3, 678 (53.3%) had at least one doctor-diagnosed respiratory infection. In logistic regression models adjusted for gender, birthweight for gestational age, maternal education, household income, neighborhood income, neighborhood education, maternal smoking during pregnancy, postnatal household smoking, breastfeeding, daycare attendance, presence of other children aged <12 in the household and season of birth, odds ratios (95% confidence interval) for respiratory infection were: 1.74 (1.02, 2.96) for <100m, 1.49 (0.85, 2.61) for 100-<200m, and 0.90 (0.68, 1.18) for 200-<1000m compared with living >1000m from a major roadway (Ptrend=0.078).
CONCLUSIONS: In this cohort study, living less than 100m from a major roadway during the prenatal period was associated with increased odds of doctor-diagnosed respiratory infection by age 3 years. Further analysis will evaluate whether respiratory infection is associated with traffic-related air pollution estimated by a validated spatio-temporal model for 24-hr measures of black carbon in the greater Boston area.