Long-Term Fine Particle Exposure in California Linked to Lower Birth Weight and Infant Mortality
A study of California infants who were born full term has shown a small but consistent effect of PM2.5 on birth weight.
Researchers matched air pollution monitoring data with California birth records. The pollution measurements were collected within 5 miles of the mother’s residence, and were averaged for the time period corresponding to the pregnancy. California mothers who lived in areas with the highest PM2.5 exposures during their pregnancy delivered slightly smaller babies, by 30 grams, compared to those with lower exposures, after controlling for demographic factors and carbon monoxide. No associations were observed between carbon monoxide and birth weight.
The authors noted several limitations of their study including difficulty in deciding on an appropriate time period for exposure measurements, and in assigning exposures to each mother based on residence, as well as the lack of data on maternal smoking.
“These findings have important implications for infant health because of the ubiquitous exposure to fine particulate air pollution across the United States,” conclude the authors.
Particulate air pollution has been associated with infant mortality, particularly for respiratory causes and sudden infant death syndrome. A follow-up study by the same research group linked PM2.5 monitoring data to infants born in California in 1999 and 2000 using the addresses of mothers who lived within five miles of a monitor.
Each infant who died was matched to 4 infants who lived to age 1 by birth weight category and date of birth. For each matched set, researchers calculated exposure as the average PM2.5 concentration over the lifetime of the infant who died. The results “add further evidence of a particle effect on respiratory related postneonatal infant mortality,” according to researchers.
Parker JD, Woodruff TJ, Basu R, Schoendorf KC. Air Pollution an Birth Weight Among Term Infants in California. Pediatrics 2005; 115:121-128.
For a copy of the abstract click here.
Woodruff TJ, Parker JD, Schoendorf KC. Fine Particulate Matter (PM2.5) Air Pollution and Selected Causes of Postneonatal Infant Mortality in California. Environ Health Perspec 2006; doi:10.1289/ehp.8484. Online 13 January 2006.
For a copy of the article click here.
