AIR POLLUTION AND IMMUNE STATISTICS AT BIRTH

Abstract

ISEE-101 Introduction: The literature on air pollution health effects has not provided firm data on mechanisms for associations with a variety of causes of death. We undertook a study to evaluate the relationship between daily ambient air pollution and immunity in an eastern European setting. Participants were pregnant women delivering between 1994 and 1998 in hospitals located in two districts. One district is characterized by high emissions from power plants and coal home heating; the other has consistently lower outdoor air pollution. Methods: Pregnant women were recruited when they appeared at a hospital in labor. Blood samples were obtained by venipuncture from the mother and the umbilical cord and were transported on dry ice to a laboratory for immunophenotyping to determine percentages of lymphocyte subfractions: CD3+, CD4+, CD8+, CD19+ and NK. Phenotyping was conducted on nearly 1200 deliveries, and interviews were conducted with mothers to obtain confounder information. PM2.5 and PAH’s were measured on a daily basis for five months each year, every third day for four months, and every sixth day in summers. An average exposure to each pollutant was calculated for the 14 days prior to each birth. Multiple linear regression was used to predict lymphocyte percentages from each pollutant separately. Models were adjusted for district, year, mean temperature, length of labor, anesthesia and other medications, passive smoke exposure, maternal age, previous pregnancy history, employment, education, and body mass index. Results: Neither PM2.5 nor PAHs had any noticeable effect on maternal lymphocytes. Both exposures, however, showed significant associations with cord blood percentages of CD3+, CD4+, and CD19+ cells. A 100 ng/m3 increase in 14-day average PAH exposure resulted in a 2.7% decrease in the percentage of CD3+ lymphocytes, a similar effect for CD4+ lymphocytes, and a 2.0% increase in CD19+ lymphocytes. For CD3+ and CD4+, these associations tended to be strongest when temperature was averaged over 3-days. Discussion: In earlier work on a smaller sample, we reported alterations in both maternal and cord lymphocytes in association with 30-day PM10. The current results for 14-day average PM2.5 and PAHs differ in observing no association with lymphocyte percentages in maternal blood. However, cord blood findings are confirmed in this larger sample, and after adjustment for temperature. Thus, this analysis demonstrates robustness of cord blood lymphocyte associations to confounding by meteorologic conditions and suggests that the fetal immune system is affected by ambient air pollutants in the absence of altered immunity in mothers. The clinical significance of these associations is unclear.