Children and Leaded Aviation Fuel
"A Geospatial Analysis of the Effects of Aviation Gasoline on Childhood Blood Lead Level": Implications for children living near airports in Oregon?
In July of 2011 Miranda et al. published a study (Miranda 2011 Study) analyzing blood lead levels of children living around airports in six counties of North Carolina. The Miranda 2011 Study, entitled "A Geospatial Analysis of the Effects of Aviation Gasoline on Childhood Blood Lead Level[i]," was conducted by the Children's Environmental Health Initiative, Nicholas School of the Environment, Duke University, Durham, North Carolina.
The Miranda 2011 Study analyzed blood lead surveillance data obtained between 1995 and 2003 which was available for 125,197 children. Of these children, 13,478 lived within 2000 meters of an airport in the six study counties. Blood lead levels were 3.88 ± 2.94 (µg/dL) in the children. [A blood lead level at 2 standard deviations above the mean therefore would be 9.76 µg/dl.] The children's ages ranged from 9 months old to 7 years old. Children living within 500 meters, 1000 meters, or 1500 meters of an airport had average blood lead levels that were 4.4%, 3.8%, or 2.1% higher, respectively, than other children.[ii]
The authors state that, "lead from aviation gasoline may have a small (2.1% - 4.4%) but significant impact on blood lead levels in children who live in close proximity to airports where avgas is used. Importantly, the magnitude of the estimated effect of living near airports was largest for those children living within 500 m [meters] and decreased in a monotonic fashion out to 1500 m [meters]."[iii]
The Miranda 2011 Study concluded, "living within 1000 m [2/3 mile] of an airport where aviation gasoline is used may have a significant effect on blood lead levels in children. Our results further suggest that the impacts of aviation gasoline are highest among those children living closest to the airport."[iv]
It should be noted that in the Miranda 2011 Study "the average estimated lead emissions across airport/heliport facilities was only 0.04 tons."[v] The authors also note that at the Charlotte/Douglas International (CLT) airport, which they note has an estimated lead emission of 0.75 tons per year, a larger discrepancy in average blood lead levels was noted: "We found the largest discrepancy in average blood lead levels between children living within 1,500 m and those whose residence was beyond this threshold (4.39 versus 3.89 µg/dL, respectively)."[vi] This is an 11.4% difference.
According to the Centers for Disease Control, "no level of lead in a child's blood can be specified as safe."[vii]
A work group established in 2002 by the CDC Advisory Committee on Childhood Lead Poisoning Prevention determined that, "The overall weight of available evidence supports an inverse (negative) association between BLLs [Blood lead levels] <10 µg/dL and the cognitive function of children...For health endpoints other than cognitive function (i.e., ...other neurologic functions, stature, sexual maturation, and dental caries), consistent associations exist between BLLs <10 µg/dL and poorer health indicators."[viii]
"In the past, motor vehicles were the major contributor of lead emissions to the air. As a result of EPA's regulatory efforts to reduce lead in on-road motor vehicle gasoline, air emissions of lead from the transportation sector, and particularly the automotive sector, have greatly declined over the past two decades. Major sources of lead emissions to the air today are ore and metals processing and piston-engine aircraft operating on leaded aviation gasoline..."[ix] In 2002 an estimated 622.8 tons of lead were emitted from aviation activity in the United States.[x] This is approximately 45% of total lead emitted in the U.S. in 2002.[xi]
In Oregon, for 2002, the EPA has estimated[xii] lead emissions from landing and takeoff activity of piston-engine aircraft as follows: Hillsboro Airport (0.6 tons / year, 30th highest in nation), Portland International Airport (0.4), Eugene's Mahlon Sweet Field (0.2), Aurora State Airport (0.2), Scapoose Industrial Airport (0.2), McMinnville Municipal Airport (0.2), Troutdale Airport (0.2), Medford's Rogue Valley International Airport (0.2), Deschutes' Roberts Field (0.1), Salem's McNary Field (0.1), Astoria Regional Airport (0.1), Polk County's Independence State Airport (0.1), Clackamas' Mulino Airport (0.1), Klamath Falls Airport (0.1), Umatilla County's Eastern Oregon Regional Airport (0.1), Lane County's Hobby Field (0.1), and the Dalles' Columbia Gorge Regional Airport (0.1). Notably, the estimate of lead emissions neglects lead emitted during the cruise phase of flight.
The Miranda 2011 study[xiii] demonstrates a small but significant increase in blood lead levels in children living within 2/3 of a mile of an airport. In addition, the range of blood lead levels (3.88 ± 2.94 µg/dL) raises concern that, at least in North Carolina, children have worrisome blood lead levels. By comparison, in 1992 Smith et al. estimated pre-industrial blood lead levels of 0.016 µg/dL.[xiv]
If efforts to maximally reduce childhood lead toxicity are to succeed lead pollution from aviation sources must be seriously considered.
[i] Miranda ML, Anthopolos R, Hastings D 2011. A Geospatial Analysis of the Effects of Aviation Gasoline on Childhood Blood Lead Levels. Environmental Health Perspectives (ehp) 119:1513-1516. (7/13/11). http://dx.doi.org/10.1289/ehp.1003231
[ii] Ibid."Results" section.
[iii] Ibid."Discussion" section.
[iv] Ibid."Conclusions" section.
[v] Personal communication with the Miranda Study authors, 10-9-11 email.
[vi] Personal communication with the Miranda Study authors 10-9-11 email.
[vii] "Preventing Lead Poisoning in Young Children", A Statement by the Centers for Disease Control and Prevention, (August 2005), pg. 1. http://www.cdc.gov/nceh/lead/publications/PrevLeadPoisoning.pdf
[viii] Ibid., Appendix. "A Review of Evidence of Adverse Health Effects Associated with Blood Lead Levels <10 µg/dl in Children." pg.iv.
[ix] Lead in Air, Basic Information, Nature and Sources of Lead. U.S. EPA at http://www.epa.gov/airquality/lead/basic.html
[x] U.S. Environmental Protection Agency. Lead Emissions from the Use of Leaded Aviation Gasoline in the United States - Technical Support Document. (EPA20-R-08-020).(October 2008)Assessment and Standards Division Office of Transportation and Air Quality, pgs. 3 and 7, http://www.epa.gov/ttn/chief/net/tsd_avgas_lead_inventory_2002.pdf
[xi] Ibid., page 9.
[xii] Ibid., pages 11- 82
[xiii] Miranda, et al., 2011.
[xiv] Preventing Lead Poisoning in Young Children. A Statement by the Centers for Disease Control and Prevention. (August 2005), Appendix . "A Review of Evidence of Adverse Health Effects Associated with Blood Lead Levels <10 µg/dl in Children." pg. 3. http://www.cdc.gov/nceh/lead/publications/PrevLeadPoisoning.pdf