Concentrations of lead in the air remain substantial in developed and developing countries, largely the result of industrial emissions. Even with the decline in lead in gasoline, developed countries, including the United States, still have substantial air lead emissions and in part as a result, blood lead levels in children are high worldwide. In a new study, researchers used data on lead emissions in the air to estimate the effects of air lead concentration on infant mortality. The study found a statistically significant relation between air lead concentration and infant mortality.
Conducted by researchers at Carnegie Mellon University, Boston College, and Hunan University, the study is an NBER Working Paper.
"Although many studies have examined the adverse effects of lead on children's cognitive and behavioral outcomes, few have analyzed the effect of exposure to lead on infants' health, so we know little about the extent of harm to infants' health from airborne lead in settings with modern medical care and at modern exposure levels," explains Karen Clay, professor of economics and public policy at Carnegie Mellon's Heinz College, who led the study.
Lead is known to cause adverse health effects in humans across a range of exposures. In this study, researchers used data on lead emissions from the U.S. Toxic Release Inventory (TRI), which was created in 1986 in response to chemical releases in Bhopal in 1984 and in West Virginia in 1985; the TRI covers 650 chemicals. The causal effect of lead on infant mortality is identified by annual variation in air fugitive lead emissions interacted with wind speed near reporting plants, which together determine local ambient lead concentration.
Researchers also analyzed lead monitor data from the Environmental Protection Agency (EPA)'s Air Quality System, wind data from the National Centers for Environmental Information, and infant health data from the National Vital Statistics system of the National Center for Health Statistics. The study included 127 U.S. counties that have plants with lead emissions within two miles of EPA lead monitors and within 10 miles of a wind monitor.
Higher concentrations of lead in the air caused higher levels of infant mortality in infants' first month and first year, suggesting that both in utero and environmental exposures matter, the study found. In addition, higher lead concentration boosted deaths from low birthweight, sudden unexplained infant death, and respiratory and nervous system causes.
"Back-of-the-envelope calculations indicate that declines in fugitive lead emissions prevented 34 to 59 infant deaths per year, generating benefits of $380 million to $670 million annually," says Edson Severnini, associate professor of economics at Boston College, who coauthored the study.
"In the United States, industrial firms and the aviation industry still emit hundreds of thousands of pounds of lead into the air," notes Xiao Wang, assistant professor of economics and trade at Hunan University, who coauthored the study. "Our new estimates can inform investments in reducing air lead emissions and soil cleanups."
The research was funded by Heinz College at Carnegie Mellon University.
