ATS 2012, SAN FRANCISCO – The link between prenatal exposure to air pollution and childhood lung growth and respiratory ailments has been established by several studies in recent years, and now a new study suggests that these prenatal exposures can be especially serious for children with asthma.
The study will be presented at the ATS 2012 International Conference in San Francisco.
"In this study, we found that prenatal exposures to airborne particles and the pollutant nitrogen dioxide adversely affect pulmonary function growth among asthmatic children between 6 and 15 years of age," said study lead author Amy Padula, PhD, post-doctoral fellow at the University of California, Berkeley. "This analysis adds to the evidence that maternal exposure to ambient air pollutants can have persistent effects on lung function development in children with asthma."
The study was conducted as part of the Fresno Asthmatic Children's Environment Study (FACES) – Lifetime Exposure initiative, which examines the influence of prenatal exposure to a number of ambient air pollutants on the growth of lung function during childhood and teen years in a high pollution area.
For this analysis, the researchers included repeated evaluations of 162 asthmatic children between the ages of 6 and 15 and their mothers. To determine prenatal exposure levels to pollution, the mothers' residences during pregnancy were geocoded and pollutant concentrations were obtained from the Aerometric Information Retrieval System supported by the U.S. Environmental Protection Agency (EPA).Monthly average pollutant concentrations were assigned from 24-hour averages obtained at a central site monitor and summaries of the entire pregnancy and each trimester were calculated. The researchers looked at several pollutants, including carbon monoxide, nitrogen dioxide, ozone and particulate matter.
To calculate lung function growth, which is determined primarily by changes in lung capacity as a child grows, the researchers used spirometry, a technique which measures the volume and speed of air as it is exhaled from the lungs. For this study, multiple lung function tests were performed and significant changes were noted in four measurements: the FVC, or forced vital capacity, which reflects the volume of air that can be blown out after fully inhaling; the FEV1, or forced expiratory volume in 1 second, which is the volume of air that can forcibly be blown out in one second, after fully inhaling; the FEF, or forced expiratory flow, which reflects the flow of air coming out of the lungs during the middle portion of a forced exhalation; and the PEF, or peak expiratory flow, which is the maximal flow achieved when air is forcibly exhaled immediately after being inhaled.
Measurement models were performed separately for boys and for girls, and were adjusted for height, age, race and socioeconomic status.
At the conclusion of the study, the researchers found that exposure to nitrogen dioxideduring the first and second trimesters was associated with lower pulmonary function growth in both girls and boys in childhood. Among girls, exposure to nitrogen dioxide during the first trimester was associated with lower FEV1 growth and exposure to nitrogen dioxide during the second trimester was associated with lower FEF growth. Among boys, nitrogen dioxide exposure during the first and second trimesters of pregnancy was associated with lower FVC growth. Exposure to particulate matter during the first trimester was associated with lower FEV1 and FVC growth in girls; similar exposures during the third trimester were associated with lower PEF and FEF growth among boys.
"This finding adds to the evidence that current air pollution levels continue to have adverse effects on human health," Dr. Padula said. "Few studies have examined prenatal exposure to air pollution and subsequent lung function in childhood. These results suggest that we need to be doing a better job to reduce traffic-related air pollution.
Dr. Padula said she and her colleagues hope to conduct future studies on the role of genetic susceptibility to air pollution.
"Currently, our studies are examining the associations between prenatal air pollution and adverse birth outcomes," she noted. "It would be useful to know what makes some people more or less susceptible to the adverse affects of air pollution so we might be able to provide more targeted public health advice."
"Exposure To Air Pollution During Pregnancy And Pulmonary Function Growth In The FACES LiTE Cohort" (Session A49, Sunday, May 20, 2012: 8:15 a.m. - 4:30 p.m., Area A, Moscone Center; Abstract 31611)
* 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.
Abstract 31611
Exposure To Air Pollution During Pregnancy And Pulmonary Function Growth In The FACES LiTE Cohort
Type: Scientific Abstract
Category: 06.01 - Air Pollution: Epidemiology and Mechanisms (EOH)
Authors: A.M. Padula1, O. Humblet2, K. Mortimer1, F. Lurmann3, I. Tager1; 1University of California, Berkeley - Berkeley, CA/US, 2University of California, San Francisco - San Francisco, CA/US, 3Sonoma Technology Inc. - Sonoma/US
Abstract Body
Background: Previous studies have found associations between prenatal exposure to air pollution and pulmonary function in childhood. Questions still remain about the impact of these exposures during pregnancy, particularly among susceptible groups such as asthmatic children. The Fresno Asthmatic Children's Environment Study (FACES) – Lifetime Exposure examines the influence of prenatal exposure to a number of ambient air pollutants on the growth of lung function in childhood and teen years in a high pollution area.
Methods: Based on maternal self-report, we geocoded all residences during pregnancy with Tele-Atlas. Pollutant concentrations were obtained from the Aerometric Information Retrieval System supported by the U.S. Environmental Protection Agency. Monthly average pollutant concentrations were assigned from 24-hour averages obtained at a central site monitor and summaries of the entire pregnancy and each trimester were calculated. We used mixed models to estimate the association between air pollutants (carbon monoxide, nitrogen dioxide (NO2), particulate matter <10 microns per cubic meter (PM10), and ozone) and pulmonary function growth as defined by repeated measures of pulmonary function tests (PFTs) (i.e., FEV1, FVC, PEF, FEF25-75/FVC, FEF25, FEF75) between the ages of 6 and 15. Models were performed separately for girls and boys and the natural log of each PFT was regressed on each pollutant during each exposure period. The models were additionally adjusted for the natural log of height, age, race and socioeconomic status.
Results: Our analysis included 162 children with a total of 1192 observations. NO2 exposure during the first and second trimesters were associated with lower pulmonary function growth in both girls and boys in childhood. Among girls, NO2 during the first trimester was associated with lower FEV1 growth and exposure to NO2 during the second trimester was associated with lower FEF25 growth. Among boys, NO2 exposure during the first and second trimesters of pregnancy were associated with lower FVC growth. PM10 exposure during the first trimester was associated with lower FEV1 and FVC growth in girls. PM10 exposure during the third trimester was associated with lower PEF and FEF25 growth among boys in childhood.
Discussion: We found that prenatal exposures to NO2 and PM10 adversely affect pulmonary function growth among asthmatic children between and 6-15 years of age. This analysis adds to the evidence that maternal exposure to ambient air pollutants can have persistent effects on lung function development in children with asthma.
Funded by: American Lung Association and California Air Resources Board.