Lead and Mercury

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Lead and Mercury

• Christine L. Johnson, MD
• Commander, Medical Corps, United States Navy
• Childrens Environmental Health Faculty Champions
  Initiative

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Washington Post Saturday January 22, 2005
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NewsweekMay 2006
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Goals and Objectives

• Lead and Mercury
• Risk factors for exposure
• Clinical significance
• Diagnosis
• Treatment

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Case 2

• An 18 month-old male comes in to your office for
  a well baby visit. He is otherwise well, but
  parents have concern because at previous visits
  his lead level was elevated.
• 12 month visit
• lead 15 micrograms/deciliter
• Education and anticipatory guidance given

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Case 2

• 15 month visit
• Repeat venous lead 18 micrograms/dl
• Family hired private environmental testing
  company to evaluate potential sources of lead.
• No lead paint was found

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Case 2

• 18 month visit
• Repeat venous lead 23 micrograms/dl
• A source of ongoing lead exposure has not been
  identified. What do you do?

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Lead

• A metal found in the earths crust
• Many uses including batteries, ammunition,
  solder, brass and bronze, pipes and ceramic
  glazes

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Lead

• Leaded gasoline additives (tetraethyl and
  tetramethyl lead)
• phased out in the 1980s
• banned as of 1996
• Also used in medical, scientific
• and military equipment

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Lead

• Used in oil based paints as a drying agent
• Phased out in 1950s and 1960s
• Banned in 1978

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Lead

• Exposure
• Eating or drinking contaminated food or drink.
• Spending time in areas where leaded paints are
  deteriorating.
• Occupational exposures.
• Using health-care products or folk remedies.
• Hobbies that involve lead.

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Lead

• Absorption
• Ingested lead is absorbed through the stomach.
• It initially travels to soft organs and most is
  excreted through urine or feces, but what is left
  goes to bones and teeth.

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Lead

• Clinical Effects
• Nervous system
• Hematologic
• Cardiovascular
• ???Cancer

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Lead

• Neurologic
• Long-term exposure
• weakness in fingers, wrists, and ankles
• High levels
• clumsiness, agitation or decreased activity and
  somnolence
• may progress to vomiting, stupor and convulsions

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Lead

• Neurologic
• Fetal and early childhood exposure
• Slow mental development
• Lower IQ
• Abnormal social-behavioral conduct

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Lead

• Hematologic
• Levels gt25 micrograms/dl can interfere with heme
  synthesis leading to anemia

Normal
Hypochromic Microcytic Anemia
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Lead

• Cardiovascular
• May cause elevations in blood pressure
• Cancer
• Animal studies have linked large doses with
  kidney tumors in mice and rats

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Lead

• Treatment
• lt 10 micrograms/dl- no treatment
• 10- 20 micrograms/dl- investigation for source
• gt15 micrograms/dl- environmental and medical
  evaluation
• gt45 micrograms/dl and exposure has been
  controlled, treat with succimer (consult an
  experienced pediatrician)
• gt70 micrograms/dl treat with parenteral EDTA

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Lead

• Canfield et al, NEJM April 2003
• Intellectual Impairment in Children with Blood
  Lead Concentrations below 10 micrograms per
  Deciliter
• 172 children
• Lead levels at 6,12,18,24,36,48,60 months
• Stanford Binet IQ testing at 3 and 5 years
• 101 had blood lead levels lt10 microgram per
  deciliter
• strong inverse relationship between blood lead
  level and IQ at age 3-5 years.

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Case 2- Lead

• At 18 months and a blood lead of 23
  micrograms/deciliter, the pediatrician contacted
  the Department of Health and the local PEHSU.

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Case 3

• Parents come in to your office for a first time
  visit with their 3 year old son who has been
  diagnosed with Autism. They are requesting that
  you draw blood from their son so that they can
  have it tested at an outside lab to confirm that
  he has elevated Mercury levels, before he begins
  chelation therapy.

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MercuryPediatric Annals July 2004
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Mercury

• Elemental Quicksilver
• Inorganic mercury
• Organic mercury
• Methyl
• Ethyl
• Phenyl

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Mercury

• Elemental Quicksilver

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Mercury

• Inorganic mercury

Nelson Textbook of Pediatrics
Rocaz, Linfantile Acrodynie, 1931
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Mercury

• Organic mercury
• Methyl
• Ethyl
• Phenyl

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Mercury
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MercuryScientific Evidence

• Long-term studies in Faroe and Seychelle Islands
  on fish eating populations
• Children closely followed for 14 years with
  specific developmental and neurological screening
  tools

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MercuryScientific Evidence

• Faroe Islands
• Consume small amounts of fish (1-3 meals/week)
• Have episodic feasts of pilot whale
• Subtle adverse
• neurodevelopmental deficits apparent

• Seychelle Islands
• Consume large amounts of fish (12 meals/week)
• No neurodevelopmental deficits apparent

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Mercury

• FDA and EPA Consumer Advisory 2004
• Dont eat shark, swordfish, king macarel or
  tilefish
• Eat up to 12 oz (2 average meals) per week of a
  variety of fish (with lower mercury levels)

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Mercury

• FDA and EPA Consumer Advisory 2004
• Albacore has more mercury than chunk light tuna
• Check local fish advisories
• Follow the same rules when feeding children, but
  serving sizes should be less

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MercuryScientific Evidence

• Institute of Medicine 2004 Report
• Review of scientific evidence
• No link between thimerosal in vaccines and
  autistic spectrum disorder
• Denmark 467,450 children
• US gt100,000 children
• UK gt100,000 children

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Mercury

• Diagnosis
• Identify and remove source of exposure
• Organic mercury compounds can be measured in
  blood or hair
• Elemental and inorganic mercury exposure can be
  measured in 24 hour urine collection

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Mercury

• Treatment
• Controversial and limited
• Chelation- not FDA approved
• D-Penicillamine
• 2,3 DMSA
• N-Acetylcysteine

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Mercury

• Chelation therapy may be harmful!
• D-Penicillamine and 2,3 DMSA enhance urinary
  excretion, but may increase brain concentrations
  of mercury
• N-Acetylcysteine may enhance urinary excretion
  without increasing brain concentrations

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Case 3- Mercury

• What do you do???
• Draw blood for the parents to have sent to a
  private lab?
• Order neurodevelopmental evaluation?
• Discuss with parents the evidence regarding
  mercury links with autism and other
  neurodevelopmental disabilities?

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Mercury Resources

• www.mercuryaction.org
• www.mercurypolicy.org
• www.epa.gov/waterscience/fish
• www.noharm.org/us/mercury/issue
• www.envirohealthaction.org/toxics/heavy_metals/Mer
  cury/
• www.nrdc.org/health/effects/mercury/index.asp
• www.sierraclub.org/mercury/
• www.environmentaldefense.org/subissue.cfm?subissue
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• www.ewg.org/issues/siteindex/issues.php?issueid50
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• www.iceh.org/pdfs/LDDI/PracPrevention/mercury.pdf
  
• Provided by Laura Anderko, RN, PhD, University of
  WisconsinMilwaukee

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Environmental Health Resources

• www.epa.gov
• www.atsdr.cdc.gov
• www.aoec.org
• www.aap.org

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Environmental Health Resources

• AAP Green Book
• 1-866-THEAAP1
• AAP Policy Statements, Clinical Reports,
  Technical Reports, CPGs
• http//aappolicy.aappublications.org/

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Contact Information

• Leyla Erk McCurdy
• Senior Director, Health Environment
• National Environmental Education Foundation
  (NEEF)
• Email mccurdy_at_neefusa.org
• Phone [phone]
• NEEF is tracking pediatric environmental health
• education activities for health care providers
  and requests your feedback
• http//www.neefusa.org/health.htm