Apparent threshold of lead's effect on child intelligence
- Harvard Medical School, Boston, MA (United States) National Taiwan Univ., Taipei (China)
- National Taiwan Univ., Taipei (China)
The developing human brain is perhaps the most sensitive of the many targets of lead toxicity. This particular sensitivity is a driving factor in setting health and environmental standards for lead. A recent compilation of studies of the association between lead and IQ has shown a consistent dose-response pattern across the range of reported exposures. In surveying the neurotoxicity of lead in humans and animals, there has been speculation of the existence of a threshold for these effects which may become apparent at lower lead levels. In that context we examined our data of tooth lead and IQ scores to determine whether there was any apparent threshold for this effect. This cohort's lead levels are among the lowest documented and provide the opportunity to extend downward the range of interest. Family factors are the strongest predictors of a child's intelligence, in particular the parent's intelligence. We therefore followed the model of Perino and Ernhart (1974) by examining whether at various levels of lead there is a disruption of the usual association between family and child intelligence. As noted by Bellinger and Needleman (1983), a difference in the correlations between parental and child intelligence in two groups, high and low lead, may be an artifact of other relationships among the predictor variables. Accordingly, they recommend a more appropriate test that would search for differences in the IQ deficits according to lead level, where the IQ deficit is the difference between a child's observed IQ and the IQ predicted from all available information about the child aside from lead. This is especially appropriate when the lead exposure correlates with the family's educational background. We examined our data this way. 12 refs., 1 fig., 2 tabs.
- OSTI ID:
- 6520203
- Journal Information:
- Bulletin of Environmental Contamination and Toxicology; (United States), Vol. 48:5; ISSN 0007-4861
- Country of Publication:
- United States
- Language:
- English
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CHILDREN
BRAIN
LEAD
BIOLOGICAL EFFECTS
DOSE-RESPONSE RELATIONSHIPS
ECOLOGICAL CONCENTRATION
TOXICITY
AGE GROUPS
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CENTRAL NERVOUS SYSTEM
ELEMENTS
METALS
NERVOUS SYSTEM
ORGANS
560300* - Chemicals Metabolism & Toxicology