Infant Mortality and Air Pollution: A Comprehensive Analysis of U.S. Data for 1990

Abstract

This paper uses U.S. linked birth and death records to explore associations between infant mortality and environmental factors, based on spatial relationships. The IMPLICATIONS Air pollution has been one of many suspected risk factors for SIDS, as well as for other causes of infant mortality. A previous epidemiologic study based on geographic gradients found a relationship between SIDS and PM 10 and speculated that fine particles (PM 2.5 ) might be the real culprit. However, U.S. data on SIDS clearly show a strong geographic gradient from east to west that has existed for decades, with SIDS rates in the mountain states nearly 4 times those in the big population centers of the east coast. Given that east-west air pollution patterns have changed dramatically during this period, it appears that other geographic factors should be considered. This conclusion is also supported by long-term trends in SIDS in the United States and in Scandinavia that show a dramatic increase with a subsequent decrease during a period of improving air quality.Our study considered some of those other factors, and while we confirmed a positive spatial relationship with PM 10 in 1990, we found an even stronger negative relationship with SO 4 2-aerosol, which is often a major constituent of fine particles. Thus, our study provides no support for the hypothesis that SIDS is associated with outdoor ambient concentrations of generic fine particles. Instead, the underlying implication is that epidemiologic studies based on geographic patterns can be misleading if a broad range of alternative hypotheses and candidate confounders is not also investigated. For example, we found that the variability in the association between SIDS and PM 10 due to alternative regression model specification and to the selection of locations to be considered was much larger than the variation obtained using the baseline model with different mortality end points and infant subgroups. SIDS constitutes a source of profound personal tragedy, and it is incumbent upon the research community to use the best possible science to investigate ways that SIDS risks might be reduced with some assurance of certainty.analysis considers a range of infant mortality end points, regression models, and environmental and socioeconomic variables. The basic analysis involves logistic regression modeling of individuals; the cohort comprises all infants born in the United States in 1990 for whom the required data are available from the matched birth and death records. These individual data include sex, race, month of birth, and birth weight of the infant, and personal data on the mother, including age, adequacy of prenatal care, and smoking and education in most instances. Ecological variables from Census and other sources are matched on the county of usual residence and include ambient air quality, elevation above sea level, climate, number of physicians per capita, median income, racial and ethnic distribution, unemployment, and population density. The air quality variables considere...

Air Pollution and Sudden Infant Death Syndrome

“…11 A second study found no increase in daily SO 2 levels on days of SIDS, compared with 1 and 2 weeks before and after, 12 whereas a third study reported a correlation between SIDS and elevated levels of gas pollutants (SO 2 , NO 2 , CO, and hydrocarbons) 7 weeks before the event. 13 Lipfert et al, 5 in reviewing their results and those of others, cautioned against attributing differences in SIDS rates to air pollution when there may be other observable but as yet unexplained differences between regions that influence mortality rates. The present report makes a significant contribution by confirming an adverse effect of air pollution in a large population study using a study design that is not confounded by differences among populations or geographic areas (a potential weakness of previous studies that compared regions).…”

“…SIDS rates were not adjusted for birth weight or income, and gaseous pollutants were not considered in the study. Another cross-sectional study, by Lipfert et al, 5 found an association between levels of particulates, but not gases, and SIDS incidence, with an unadjusted odds ratio of 1.42 (no confidence interval given) between metropolitan statistical areas with low versus high levels of PM 10 pollution (27.5 and 50.9 g/m 3 , respectively). This association persisted after adjustment for several factors including gender, ethnic background, birth weight, mother's aid, adequacy of prenatal care, smoking, and education.…”

“…Many risk factors have been identified and publicized, including the winter season, 2,3 lower social status of parents, 4 environmental tobacco smoke, 1,4 and the prone position. 2 The role of ambient air pollution has received little attention, is controversial, 3,5,6 and is not often considered in epidemiologic studies and reviews of SIDS. 1,2,4 One reason why the influence of air pollution on SIDS has received relatively little attention is related to the challenging methodologic issues involved.…”

Estimating the global abundance of ground level presence of particulate matter (PM2.5)

“…In recent years, researchers are finding it worthy to investigate potential links between PM 2.5 exposure and adverse birth outcomes (Slama et al, 2008;Dadvand et al, 2013), epigenetic alteration (Baccarelli et al, 2008;Salam et al, 2012;Byun et al, 2013;Hou et al, 2013) infant mortality (Woodruff et al, 1997;Lipfert et al, 2000;Dales et al, 2004;Glinianaia et al, 2004) atherosclerosis (Araujo et al, 2008;Araujo, 2011;Kaufman, 2011), stroke (Brook, 2008;Brook andRajagopalan, 2009, 2012;Maheswaran et al, 2010Maheswaran et al, , 2012, rheumatic autoimmune disease (Zeft et Table 1. Particulate matter and health outcomes for PM 10 , PM 2.5 and ultrafine particles (UFPs).…”

Using Machine Learning to Estimate Global PM2.5 for Environmental Health Studies

“…In recent years, researchers are finding it worthwhile to investigate a link of PM 2.5 exposure with adverse birth outcomes, 21,22 epigenetic alteration, [23][24][25][26][27][28][29][30][31][32][33][34][35][36] infant mortality, [37][38][39][40][41][42] athero sclerosis, [43][44][45] stroke, 46-50 rheumatic autoimmune diseases, 51,52 central nervous system disorders, [53][54][55][56][57] and diabetes. [58][59][60] Since many of these health conditions are interlinked, comprehensive studies are required to better understand the impact of PM 2.5 .…”