The Effects of Lead Exposure on Children
July 26, 2012
Oregon Aviation Watch is highly concerned about the environmental and health impacts of lead emissions from general aviation airports. According to Port of Portland documentation, Hillsboro Airport, in particular, emits 0.7 tons of lead annually into the air. It ranks 21st out of nearly 20,000 airports in the nation in lead emissions. Additional lead is also released by other airports and piston engine aircraft throughout the region. See Aviation Lead Cloud Over Oregon for additional information regarding aviation generated lead in Oregon.
To better understand the effects of lead on the human organism, Oregon Aviation Watch is researching related medical literature. The following commentary, "If Ever A Time for Precaution" by Joel Nigg, Ph.D., was included in an article by Claire Cole and Adam Winsler entitled "Protecting Children from Exposure to Lead".
Cole and Winsler rightly refocus our attention on the once-forgotten story of lead exposure and child health. The story of lead provides an object lesson for policymakers. Decades after lead came into routine consumer and industrial use, scientists are still grappling with its subtle yet extraordinarily costly effects on children's development. It has been horrifying to discover that much of the deleterious effect of lead on cognition and behavior occurs at the beginning of exposure - equivalent to exposures still commonplace in America. The unusual consistency of findings showing that lead is correlated, even at levels still typical in the U.S. population, with lower IQ and attention-deficit/hyperactivity disorder (ADHD) is sobering for a field accustomed to conflicting and ambiguous scientific reports.
The increasingly well-documented effects on ADHD are important because ADHD develops very early and is a precursor to conduct disorder, delinquency, substance use disorders (Mannuzza et al., 2008; Martel et al., 2008), and other outcomes of major concern to society. Attention problems predict academic failure over and above externalizing problems (Breslau et al., 2009). In our data, decrements in attention problems due to lead exposure fully account for decrements in IQ, but not the reverse (Nigg et al., 2008), suggesting that lead damage to regulatory systems in the brain may also account for the well documented impacts on IQ. In short, the cascade of developmental effects beginning early in life that may be related to insults, like seemingly modest lead exposure, is of major concern to society.
Now policymakers, who many believed had dealt with lead a generation ago, have to grapple with two issues. The first is determining whether further reductions in societal lead burden are needed. The even more momentous issue is what to do about future potential neurotoxins. The regulatory policies of the past century have amounted in one sense to a colossal experiment on America's children, not only with lead but hundreds of other substances. What happens to children when exposed to lead? To the hundreds of new chemical compounds permitted in the past decade? To the dozens of new nanotechnologies now coming to market? Policymakers should learn from the lead experience that it may take decades for science to find the unfortunate answers, at enormous economic cost to society. Moreover, medical study of the health effects will never catch up with the pace of compounds being developed. Such an approach wastes scientific time and resources, diverting those efforts from finding cures to other serious disease.
These observations raise serious ethical and policy problems for domestic industry and government. Policymakers and industry need to grapple more honestly with applying a well-defined precautionary principle to potential neurotoxins − both chemical and nano − as is now required prior to the release of pharmaceuticals. Such an approach shifts the burden of proof for a potentially dangerous action from acting until proven dangerous, to waiting until proven safe. Extreme application of the principle can be rightly criticized, but reasonable and effective definitions, justifications, and applications are readily available (Fisher, Jones, & von Schomberg, 2006; Petrenko & McArthur, 2009) and have already been applied in international law and treaty (Fisher et al., 2006). Identifying the appropriate role of a precautionary principle in protecting children's health from potential neurotoxins is a policymaking discussion that is urgently overdue. This should be policymakers' take home realization from the present report.
Breslau, N., Breslau, J., Peterson, E., Miller, E., Lucia, V. C., Bohnert, K., & Nigg., J. (2009). Change in teachers' ratings of attention problems and subsequent change in academic achievement: A prospective analysis. Psychological Medicine, 40(1), 159-166.
Fisher, E., Jones, J., & von Schomberg, R. (2006). Implementing the precautionary principle: Perspectives and prospects. Northampton, MA: Edward Elgar.
Mannuzza, S., Klein, R. G., & Moulton, J. L. (2008). Lifetime criminality among boys with attention deficit hyperactivity disorder: A prospective follow-up study into adulthood using off cial arrest records. Psychiatry Research, 160, 237-246.
Martel, M. M., Pierce, L., Nigg, J. T., Jester, J.M., Adams, K., Puttler, L. I., et al. (2009). Temperament pathways to childhood disruptive behavior and adolescent substance abuse: Testing a cascade model. Journal of Abnormal Child Psychology, 37(3), 363-373.
Nigg, J. T., Knottnerus, G. M., Martel, M. M., Nikolas, M., Cavanagh, K., Karmaus, W., et al. (2008). Low blood lead levels associated with clinically diagnosed attention deficit hyperactivity disorder (ADHD) and mediated by weak cognitive control. Biological Psychiatry, 63(3), 325-331.
Petrenko, A., & McArthur, D. (2009). Between same-sex marriages and the large hadron collider: Making sense of the precautionary principle. Science and Engineering Ethics, Sep 12. [Epub ahead of print]
Professor Nigg is the Director of the Psychology Division in the Department of Psychiatry at the Oregon Health and Science University. "His primary research focus is on causes of ADHD and determinants of altered neural development in children. He conducts experimental studies of cognitive and neuropsychological functioning in ADHD and learning disabilities, as well as studies of genetic and environmental correlates of ADHD in population and clinical samples. He has authored a recent scholarly book on causal mechanisms in ADHD (What Causes ADHD; Guilford Press, 2006) as well as over 100 peer reviewed scientific papers on clinical and causal correlates of ADHD and developmental psychopathology. His empirical research has been funded by the National Institute of Mental Health for the past 12 years."
1. Hillsboro Airport: Parallel Runway 12L/30R Draft Environmental Assessment. Volume 2. Appendices. Prepared for the Port of Portland by CH2MHILL. (October 2009). Section. C-3., pg. 1-2.
2. EPA Memorandum from Marion Hoyer and Meredith Pedde to the Lead NAAQS Docket EPA-HQ-OAR-2006-0735, (11/1810). pg. 2-3.
3. Cole, Claire and Winsler, Adam Protecting Children from Exposure to Lead: Old Problem, New Data, New Policy Needs. Society for Research in Child Development: Social Policy Report. George Mason University. Vol. 24. No. 1. (2010) pg. 24-25.
4. Cole, Claire and Winsler, Adam Protecting Children from Exposure to Lead: Old Problem, New Data, New Policy Needs. Society for Research in Child Development: Social Policy Report. George Mason University. Vol. 24. No. 1. (2010)
5. Ibid. pg. 29.