lead symptoms and exposure route

Elemental Exposure-General
Truisms

Childhood Lead Poisoning
Why you might be smarter than your parents

• Most are not toxic
• Nutritional = less toxic (Zn, Cd)
Noel Stanton
WI State Lab of Hygiene
2601 Agriculture Drive
PO Box 7996
Madison WI 53707
[phone] [e-mail] – Homeostasis

• Abundance

= toxicity

• Every truism has exceptions

Speciation Considerations
• Can greatly influence toxicity
• Ability to differentiate limited, improving
– Cr+3 = nutrient, Cr +6 = carcinogen
– Toxicity As+3 > As+5 >>organic As

or

Exposure Routes

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Assessment
• Contamination biggest concern
– serum Al: 1970 = 1,000 µg/L, 2002 = 2 µg/L

• Ingestion—most common
• Inhalation—more dangerous

Mechanisms of Action
• Binding to SH groups
– alters protein shape

• Substitution for nutritional element

• Best sample will be element and species dependent
– correlation w/disease often limited
– Blood, urine, serum typical
– Hair is generally NOT valid

• Analytical methods
– Atomic spectrometry (AA, ICP-MS)
– Electrochemical (ion-specific electrodes, ASV)
– XRF

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Lead and Exposure
• Many uses-now~85% batteries
• Widely dispersed in environment
– U.S., huge reservoir in housing

• Well-characterized env. toxin
• Many toxic effects
• Young children most impacted
– Subclinical effects

Major Public Health Success
• Existing blood Pb threshold for action = 10 µg/dL
• 1976-80, mean blood Pb ~14.9 µg/dL (88%>10)
• 2002, mean blood Pb ~1.7 µg/dL (1.2%>10)

But…Still a Big Problem
• Nationally, 1.2% still >10, ~180,000 kids
• WI 4.7% entering school had Pb >10 (2006)
• 2111 kids (2.6% tested) >10, ~5/day (2006)

The Lead-Learning Link
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Low-level Pb effect studies began 1970’s
Linked IQ, cognitive problems with Pb
Studies replicated worldwide
Early study populations still followed
Demonstrated links to delinquency, violence, etc.
• IQ as Pb may be steepest at lower [