August 2017

Lead Poisoning in Children – A Pervasive but Preventable Problem

Dr. Joseph E. Graas, Scientific Director
Dr. Edward Moore, Medical Director
Dr. Paul Robandt, Scientific Director

The Flint, Michigan water crisis attracted international attention due to corrosion problems in older lead service lines and the lead corrosion products settling in galvanized iron pipes. 1  Although lead use in plumbing was banned in 1986, older construction may still contain lead pipes, fixtures and solder.  This problem is not isolated to older, industrial cities.  Recent findings show a higher percentage of children with elevated blood levels in areas of California than in Flint at the height of the water crisis, and more recent discoveries of lead in public school water systems in California.2,3 

Adult exposure to lead is usually via workplace exposure and therefore acute.  Most workplaces are aware of the exposure routes and how to mitigate them.  Typical industries working with lead would be mining and smelting operations, battery and electronics manufacturing, and the soldering of equipment.4

However, lower-level lead pollution is pervasive due to environmental contamination from paint manufactured prior to 1978 and lead additives used in gasoline prior to 1989.  Flaking and sanded paint from older construction result in a “halo” of lead contamination around buildings.  Likewise, when leaded fuel was used, the areas of high vehicular traffic deposited lead on the ground near roadways due to emissions.  An estimated 5.9 million metric tons of lead were emitted into the US alone, as 75% of lead additives in gasoline are emitted as exhaust particulates. 5,6  This has left heavily-trafficked urban areas with a persistent lead contamination in soils, which is typically not considered mobile except for dust blown around a contaminated area or transported via direct human intervention. 7 

In children, virtually no organ system is immune to the effects of lead poisoning.  A typical child under the age of 6 ingests 100 to 400 mg/day of dust and soil.8   Children absorb lead much more efficiently than adults, up to 50% of an ingested dose versus 10% in adults.  The organ of most concern is the developing brain.  Any disorganizing influence that affects an individual at a critical time in development is likely to have long-lasting effects, such as inattention, unpredictable disruptive behavior and loss of intelligence.

One of the mechanisms of neurotoxicity appears to be the ability of lead to substitute for other polyvalent cations with a greater affinity than calcium or zinc for protein binding sites.  This can affect many significant processes, not the least of which is the developing central nervous system.9   An increase in blood lead levels from 1 µg/dL to 10 µg/dL results in an average six-point IQ decrement.10

With proper soil, water, household, and blood testing, lead poisoning in children is completely preventable.  The economic and social cost of not testing for lead are more costly than instituting a robust testing program.11

References

  1. Kelsey J. Pieper, Min Tang, Marc A. Edwards. Flint Water Crisis Caused By Interrupted Corrosion Control: Investigating “Ground Zero” Home. Environmental Science & Technology, 2017; DOI: 10.1021/acs.est.6b04034
  2. California Department of Public Health Childhood Lead Poisoning Prevention Branch, Blood Lead Testing Results by Jurisdiction and Zip Code for Children Age < 6 Years; California 2012
  3. San Diego Unified School District webpage (https://www.sandiegounified.org/watersampling) 2017
  4. World Health Organization, Lead Poisoning and Health Fact Sheet, September 2016 (http://www.who.int/mediacentre/factsheets/fs379/en/)
  5. U.S. EPA. Environmental Criteria and Assessment Office. Air Quality Criteria for Lead. Rpt no EPA/600/8-83/028aR. Research Triangle Park, NC: U.S. Environmental Protection Agency, 1986
  6. Statement of the Ethyl Corporation. S 2609 – A Bill to Amend the Clean Air Act with Regard to Mobile Source Emission Control. Hearings before the Committee on Environment and Public Works. U.S. Senate, 98th Congress, 2nd Session. June 22, 1984
  7. Chaney, R.L., H.W. Mielke and S.B. Sterrett. 1989. Speciation, mobility, and bioavailability of Soil Lead. [Proc. Intern. Conf. Lead in Soils: Issues and Guidelines. B.E. Davies & B.G. Wixson (eds.)]. Environ. Geochem. Health 11(Supplement):105 129
  8. World Health Organization, Childhood Lead Poisoning, September 2010 (http://www.who.int/ceh/publications/leadguidance.pdf)
  9. Markowitz M (2000). Lead poisoning. Pediatrics in Review, 21(10):327–335
  10. Surkan PJ et al. (2007). Neuropsychological function in children with blood lead levels <10 microg/dL. Neurotoxicology, 28:1170–117
  11. Gould E (2009). Childhood lead poisoning: conservative estimates of the social and economic benefits of lead hazard control. Environmental Health Perspectives, 117:1162–116