Lead

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Lead is a heavy metal and a widespread environmental pollutant that can cause neurological, haematological and renal effects in exposed populations

Lead as a biomarker

Sample collection and storage

Matrix:

Blood is the best biological matrix to monitor lead exposure

Kinetics:

• Uptake generally through inhalation or ingestion
• Absorbed lead mainly stored in bones. Lead can cross the placenta and the brain- blood barriers
• Lead is mainly excreted via urine and bile
• Elimination follows the kinetics of a three compartment model with half-lives of 35 days (blood), 400 days (soft tissue), and 20 years (bones)

Sampling conditions:

Blood should be collected in containers free of any metal contamination. Samples can be stored at 4°C or frozen

Sample measurement

Analytical aspects:

• Measured through absorption spectrometry (AAS) or ICP-MS
• Sensitivity of measures is 0.05-0.1 µg/l

Performance characteristics:

Analytical reproducibility is 1-2%, inter- and intralaboratory variability is 5-10%

Validation:

Measurement methods are fully validated, intercomparison programs and certified standards and reference materials is available

Confounding factors:

Smoking, alcohol consumption, menopauses and hormone-replacement therapy

Data interpretation

Concentrations reported in literature:

Mean values:

• adults 30-50 µg/l
• children 10-30 µg/l

Critical values for children: 100 µg/l

Occupational biological dose limit: 300 µg/l

Dose-response/effect relationships:

Effects	Pb in blood (µg/l)
	Children	Adults
Cognitive or hearing impairment	50-100
Vitamin D3 reduction	100-150
Erythrocyte porphyrin elevation	150-200	200-300
Reduced haemoglobin synthesis	250-300	500
Increased urinary delta-aminolevulinic acid	400	400
Frank anaemia	700	800
Encephalopathy	800-1,000	1,000-1,200

Time trend, geographical variation, susceptibel groups:

In countries where leaded-gasoline has been banned, concentrations of lead in the blood of general population have rapidly decreased to levels that are now about 70-80% lower than those prevailing in the 1970s

See also

• Toxicokinetics of bone lead [1]
• The development of a stochastic physiologically-based pharmacokinetic model for lead
• Dietary lead intakes for mother/child pairs and relevance to pharmacokinetic models
• Kinetics of lead in bone and blood after end of occupational exposure
• Literature list of lead pharmacokinetics

[2] [3] [4] [5]