Lead
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- The text on this page is taken from an equivalent page of the IEHIAS-project.
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