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Lead exposure in early life: health consequences
1Department of Environmental Health, University of Cincinnati Medical Center, Ohio 45267-0056.
Reviews of Environmental Contamination and Toxicology
|January 1, 1990
Summary
Lead exposure, even at low levels, significantly impacts hemoprotein function and neurodevelopment. Central nervous system effects, including compromised neurobehavioral development, occur at lower lead levels than previously thought.
Area of Science:
- Environmental Health
- Toxicology
- Neuroscience
Background:
- Lead toxicity traditionally linked to hemoprotein dysfunction at higher exposure levels.
- Hemoproteins, essential for hemoglobin and drug metabolism, are affected by lead inhibition of heme synthetase.
- Previous understanding suggested a threshold of 30-40 µg/dL for lead-induced hemoprotein effects.
Purpose of the Study:
- To investigate the impact of lead exposure on hemoprotein function and neurodevelopment.
- To determine the critical lead exposure levels affecting the central nervous system, particularly in vulnerable populations.
- To evaluate the association between low-level lead exposure and neurobehavioral deficits.
Main Methods:
- Review of existing literature on lead toxicity and hemoprotein function.
- Analysis of cross-sectional and prospective studies on lead exposure and neurodevelopmental outcomes.
- Evaluation of circulating lead concentrations (PbB) in adults, children, fetuses, and neonates.
Main Results:
- Lead inhibits heme synthetase, reducing hemoglobin and cytochrome P-450 activity, with a threshold around 30-40 µg/dL.
- Evidence indicates central nervous system compromise at significantly lower lead levels, especially in fetuses and young children.
- Neurobehavioral development is affected by maternal or cord PbB below 10 µg/dL; postnatal exposure as low as 25 µg/dL is linked to cognitive and behavioral deficits.
Conclusions:
- Lead exposure poses a risk to neurodevelopment at levels previously considered safe.
- The central nervous system is a sensitive target for lead toxicity, even at low concentrations.
- Further research is needed to understand the mechanisms underlying lead's neurotoxic effects, potentially related to cell proliferation and differentiation.