Statewide North Carolina Study Finds Elevated Blood Lead Levels in Children Living Near Airports
On 8/9/2024 an article entitled Association between Residential Distance to Airport and Blood Lead Levels in Children under 6 Living in North Carolina, 1992–2015 was published in the Environmental Health Perspectives journal. This research builds on an earlier study by Marie Lynn Miranda, Rebecca Anthopolos, and Douglas Hastings published in June of 2011. This is the fifth study to find elevated blood lead levels in children living in proximity to airports where piston-engine aircraft continue to use leaded fuel.
The study, which considered the blood lead levels of 943,602 children living within 10 kilometers [6.21 miles] of airports across 100 North Carolina counties, found a "significant adverse effect of avgas use on children's BLLs [Blood Lead Levels]..."
The Introduction to the article appears below.
Even with progress in lead poisoning prevention, research has consistently shown there is no safe blood lead level (BLL) for children. Behavioral and cognitive deficits are associated with lead exposure, even at low levels. Unfortunately, many piston-engine aircraft are still fueled by leaded aviation gas (avgas).
The US Environmental Protection Agency (EPA) estimates that ∼5.2 million people live within 500m of an airport where avgas is used. Our past research in six North Carolina (NC) counties indicates that children living within 500m of airports where avgas is used have ∼4% higher BLLs than children who lived beyond 2,000m (reference group); the association between avgas and children's BLLs was still detectable at 1,000m. Building on this work, this study investigates the relationship between avgas and BLLs in children across all 100 NC counties.
In October 2023, the EPA finalized an endangerment finding as the first step in using its authority to regulate the use of avgas. EPA is now required by the Clean Air Act to propose and promulgate regulatory standards for lead emissions from certain aircraft engines. Moreover, the Federal Aviation Administration (FAA) must propose avgas that will control or eliminate lead emissions. In this paper, we provide evidence that is relevant to the EPA's future regulatory proposals.
To access the entire article click here.
Previous Airport Studies on the Effects of Leaded Avgas on Children's Blood Lead Levels
The new statewide North Carolina study was preceded by four significant studies of children's blood lead levels. The earlier studies are summarized here, with links to the full articles for readers who would like more details.
Reid-Hillview Airport Lead Study (2021)
An 8-3-2021 lead study was commissioned by Santa Clara County in response to concerns about the toxic lead emissions generated by aviation activity at the Reid-Hillview Airport (RHV). The study included an analysis of data from January 1, 2011 to December 31, 2020 of over 17,000 blood lead level samplings of children residing within one and a half miles of the airport at the time the blood draws were taken. The researchers found that "Under periods of high piston-engine aircraft traffic, children proximate to Reid-Hillview airport experience an increase in BLLs [blood lead levels] in excess of what the children of Flint experienced during the FWC [Flint Water Crisis]." The study also revealed that the volume of piston-engine air traffic and the amount of leaded fuel sold on a monthly basis to RHV fixed based operators also contributed to increased blood lead levels.
In the words of Dr. Sammy Zahran, a leading researcher on the study, "The Flint water crisis from start to finish unfolded in less than a year and a half. By contrast at Reid-Hillview, the release of lead into the lived environment is a continuous, non-stop, daily unabated flow of an undeniably harmful toxicant. I remind you that we are talking about more than a thousand pounds of lead released annually on nearby populations."
Michigan Airport Lead Study (2017)
The Effect of Leaded Aviation Gasoline on Blood Lead in Children, published in 2017, involved over 1 million children and 448 airports in Michigan. Dr. Sammy Zahran et al. found that "child BLLs: 1) increased dose-responsively in proximity to airports, 2) declined measurably among children sampled in the months after the tragic events of 9-11, resulting from an exogenous reduction in PEA [piston-engine aircraft] traffic, 3) increased dose-responsively in the flow of piston-engine aircraft traffic across a subset of airports, 4) increased in the percent of prevailing wind days drifting in the direction of a child's residence and 5) behave intuitively and significantly when considering two-way and three-way interactions of our main treatment variables."
As stated in the report, "The consequences of lead exposure in childhood are lasting. Neural-imaging studies find that adults exposed to lead as children have reduced gray matter in regions of the brain known to govern executive judgment, impulsivity and mood regulation... Economists have convincingly linked these intellectual and socio-emotional traits of judgment and impulsivity to long-term life outcomes... persons exposed to lead in early life experience ‘an unfolding series of adverse behavioral outcomes: behavior problems as a child, pregnancy and aggression as a teen, and criminal behavior as a young adult.'"
North Carolina Airport Lead Study (2011)
A Geospatial Analysis on the Effects of Aviation Gasoline on Childhood Blood Lead Levels, by Marie Miranda et al, was published in October of 2011. This study involved the observation of 125,000 blood lead levels (BLLs) in 6 North Carolina counties in proximity to the 66 airports located in these jurisdictions. According to the authors of the study, "Our results suggest that children living within 500 m of an airport at which planes use leaded avgas have higher blood lead levels than other children. This apparent effect of avgas on blood lead levels was evident also among children living within 1,000 m of airports. The estimated effect on blood lead levels exhibited a monotonically decreasing dose–response pattern, with the largest impact on children living within 500 m." In their conclusion they stated, "Our analysis indicates that living within 1,000 m of an airport where avgas is used may have a significant effect on blood lead levels in children."
Colorado Airport Lead Study (2024)
The Association Between Childhood Blood Lead Levels and Proximity to Airports in Colorado published by Springer Link on May 22, 2024, examined blood lead levels in children age 18 years and younger over a 10-year period from January 1, 2011, to December 31, 2020, in relation to 12 unidentified Colorado airports. When comparing their findings to some of the earlier studies discussed above, the researchers pointed out that, "One notable difference between the present study and the three previously published studies is Colorado's relatively smaller sample size of blood lead tests near airports. Low blood lead testing rates, especially in rural areas, are Colorado's most significant challenge to lead poisoning prevention."
Despite the smaller sample size and other limitations discussed in the study, it is significant that researchers found a correlation between blood lead levels and proximity to airports. The report went on to recommend an increase in blood lead testing, "Lowering exposure to lead lowers the risk of health effects, and new research emphasizes the danger of even low levels of exposure. Testing is critical not only to protect children who might have lead exposure but also because it provides valuable public health data needed to investigate less well-studied exposure pathways and how they affect BLLs."
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