UMEM Educational Pearls

Lead is a ubiquitous metal in the environment partly due to decades of using leaded gasoline (organic lead) and lead-based paint (inorganic lead). Outside of occupational exposure, children are disproportionately affected from environmental lead exposure.

 

Common route of exposure are:

1. Ingestion (common in children): soil, water, lead-based paint chips, toys, certain folk remedies.
   • Absorption: adult: 3 – 10% vs. children: 40 – 50%
2. Inhalation (mostly occupational exposure): lead dust
   • Absorption: 30 – 40%
3. Dermal (minor): cosmetic products
   • Absorption: < 1%

 

Majority of the absorbed lead are stored in bone (years) > soft tissue (months) > blood (30-40 days) (half-life). Thus blood lead level does not accurately reflect the true body lead burden.

 

Incidence of elevated blood lead level (EBLL > 5 microgram/dL) in children increased from 2.9 to 4.9% in Flint, MI before and after water source change. In the area with the highest water lead level, the incidence increased by 6.6%.

 

Clinical manifestation in children

Clinical severity	Typical blood lead level (microgm/dL)
Severe CNS: encephalopathy (coma, seizure, altered sensorium, ataxia, apathy, incoordination, loss of developmental skills, cranial nerve palsy, signs of increased ICP GI: persistent vomiting Heme: anemia	> 70 – 100
Mild to moderate CNS: hyperirritable behavior, intermittent lethargy, decrease interest in play, “difficult” child GI: intermittent vomiting, abdominal pain, anorexia	50 – 70
Asymptomatic CNS: impaired cognition, behavior, balance, fine-motor coordination Misc: impaired hearing or growth	> 10

 

Evaluation for lead poisoning

1. Blood lead level (BLL)
2. CBC: hypochromic microcytic anemia, basophilic stippling
3. Imaging: abdominal XR – check for foreign bodies in GI tract; long-bone XR – lead lines

 

Management of children with EBLL

1. Removal from exposure
2. Environmental investigation/intervention (BLL: 15 - 44 ug/dL)
3. Chelation
   • Asymptomatic (BLL: 45 – 69 ug/dL): Succimer (PO)
   • Symptomatic (BLL: > 70 ug/dL): Dimercaprol (IM) and CaNa₂EDTA (IV)

References

1. Dapul H, Laraque D. Lead poisoning in children. Advances in pediatrics 2014;61:313-333.
2. Hanna-Attisah M. et al. Elevated blood lead levels in children associated with the Flint drinking water crisis: a spatial analysis of risk and public health response. AM J Public Health 2016;106:283-290.
3. Goldfrank's Toxicologic Emergencies 10th ed.