Persistent threat of lead: medical and sociological issues
Lead exposure is an ancient malady. Its history serves as a useful paradigm through which to understand many other pollutants that our technological society has inserted into the human environment and may guide preventive steps for other agents. Lead poisoning was first recognized in workers exposed to high doses. The discovery of childhood toxicity occurred a century ago in Australia, when children with striking symptoms of paralysis, ophthalmoplegia, or meningitis were found to be highly lead exposed. Encephalopathy generally occurs at blood lead levels of 80 micrograms/dL or more, but unequivocal brain damage has been demonstrated at doses well below this level. At lower doses, the neurocognitive effects of lead are expressed as diminished psychometric intelligence, attention deficits, conduct problems, alterations in the electroencephalogram, school failure, and increased referral rates for special needs. Careful epidemiologic studies, which have controlled for the important confounders, have set the effect level at 10-15 micrograms/dL. Elegant animal studies in which confounding is not an issue have confirmed these findings. Although blood lead levels in the population have dropped over time for a number of reasons, there are some 3-4 million American children with blood lead levels of more than 15 micrograms/dL. Biochemical and functional changes have been demonstrated in the heme biosynthetic pathway and in the renal, cardiovascular, endocrine, immune, and nervous systems. The threshold for effect depends on the sensitivity of the methods used. A no-effect level has not been found. Further, this is not a disease of the poor alone. But the poor are exposed to much more lead than are the more economically favored. Deficiencies in body calcium, zinc, iron, and protein stores are associated with increased uptake. Optimizing nutrition enhances the resistance to lead. 110 references.
- Research Organization:
- Univ. of Pittsburgh School of Medicine, PA (USA)
- OSTI ID:
- 6464813
- Journal Information:
- Curr. Probl. Pediatr.; (United States), Journal Name: Curr. Probl. Pediatr.; (United States) Vol. 18:12; ISSN CPPTB
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ANIMALS
BEHAVIOR
BIOLOGICAL ACCUMULATION
BIOLOGICAL MODELS
CHELATING AGENTS
DOCUMENT TYPES
ELEMENTS
ENVIRONMENTAL EXPOSURE
LEAD
MAMMALS
MAN
METABOLISM
METALS
PREGNANCY
PRIMATES
REVIEWS
TOXICITY
VERTEBRATES