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The adverse effect of marginally higher lead level on intelligence development of children: a Shanghai study
Insights
Preschool children exposed to lead pollution in Shanghai showed impaired intelligence development, particularly those over 46 months old. Higher blood lead levels significantly correlated with lower IQ scores, even after controlling for other factors.
Area of Science:
- Environmental Health
- Neuroscience
- Pediatrics
Background:
- Lead exposure is a significant environmental health concern for children.
- Neuropsychological development in early childhood is particularly vulnerable to toxic insults.
- Previous studies suggest a link between lead exposure and cognitive deficits.
Purpose of the Study:
- To investigate the relationship between blood lead levels and neuropsychological functions in preschool children.
- To assess the impact of lead toxicity on cognitive development in a lead-polluted area.
- To identify age-specific effects of lead exposure on child development.
Main Methods:
- Survey of 128 preschool children in a lead-polluted area of Shanghai.
- Assessment of blood lead levels (geometric mean 21.7 µg/dL).
- Evaluation of neuropsychological functions using age-appropriate tests like the Bayley Scales of Infant Development (BSID) and Wechsler Preschool and Primary Scale of Intelligence (WPPSI).
- Statistical analysis including step-wise regression and multiple analysis of covariance to control for confounding factors.
Main Results:
- No significant difference in BSID indices for children under 30 months, though a trend towards poorer scores in high lead group was observed.
- A highly significant negative correlation between WPPSI IQ scores and blood lead levels in children older than 46 months.
- IQ differences remained statistically significant even after controlling for 21 non-lead variables.
Conclusions:
- Children in the investigated area, especially those older than 46 months, suffer from lead toxicity impacting intelligence development.
- The findings support the view that even marginally elevated blood lead levels in children warrant serious attention.
- Lead exposure poses a significant risk to cognitive development in preschool-aged children.
Abstract:
We surveyed 128 preschool children in a lead-polluted area in Shanghai to study the relationship between blood lead level and neuropsychological functions, assessed by age-appropriate psychological tests. The geometric means of blood lead level was 21.7 + -10.8 micrograms/dl. Of 47 children aged below 30 months, there was no significant difference in BSID indices between the high and low lead subjects, although the high lead children tended to have poorer development scores than the low lead ones. On the other hand, of 81 children older than 46 months, the WPPSI IQ scores showed highly significant negative correlation with blood lead level. Step-wise regression and multiple analysis of covariance techniques were employed to find out and control the confounding factors. Even when 21 non-lead variables were considered, the IQ difference between high and low lead groups remained statistically significant. We concluded that the children, especially those older than 46 months, in the area investigated, did suffer from lead toxicity causing impairment in intelligence development. We support the view that marginally higher lead level in children should be taken seriously.