Indian J Pediatr 1992; 59 : 233-238
The Adverse Effect of Marginally Higher Lead Level on Intelligence Development of Children : A Shanghai Study Shen Xiao-ming, Guo Di, Xu Ji-de, Wang Mei-xian, Tao Su-die, Zhou Jian-de, Gao Xiao-lan, and Lou Hui--qing Shanghai hzstitute for Pediatric Researct~ Shanghai, Chhza 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 ug/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 WPPSl 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.
Key Words: Blood lead; Development; Child; Trace elements; Multivariate analyses. Although no disagreement exists about the deleterious effect of frank lead poisoning in children, opinions on marginally higher lead levels are inconsistent. Previous studies on the potential influence on the development of children failed to provide definitive evidence for or against the occurrence of neurological dysfunction. Sample heterogeneity and Reprint requests :. Dr. Shen Xiao-ming, Shanghai Institute for JPediatricResearch, Shanghai- 200 092, China. 233
inadequate assessment of lead exposure and neuropsychological function could account for discrepancies? In this study, the children were likely to have had been exposed to the same polluted environment, came from similar social backgrounds and locally standardized psychological tests were administered to assess the cognitive functions. Multivariate step-wise regression and multiple analysis of covariance were employed in order to evaluate the true
234
THE INrDIANJOURNALOF PEDIATRICS
relationship between blood lead levels and intelligence. MATERIAL AND METHODS
Subjects All the 189 children came from a day care centre in a lead-polluted area where a smeltry was located. They were enrolled in study with parental consent. The following WHO exclusion criteria 2 were applied and 46 children were excluded: (i) birthweight 0.05 > 0.05
29 29 29
87 _+ 14 90 _+ 17 86 _+ 12
52 52 52
102 _+ 11 104 _+ 12 99 _+. 12
5.1158 4.1405 4.7248
The Adverse Effect of Marginally Higher Lead Level on Intelligence Development of Children : A Shanghai Study Shen Xiao-ming, Guo Di, Xu Ji-de, Wang Mei-xian, Tao Su-die, Zhou Jian-de, Gao Xiao-lan, and Lou Hui--qing Shanghai hzstitute for Pediatric Researct~ Shanghai, Chhza 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 ug/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 WPPSl 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.
Key Words: Blood lead; Development; Child; Trace elements; Multivariate analyses. Although no disagreement exists about the deleterious effect of frank lead poisoning in children, opinions on marginally higher lead levels are inconsistent. Previous studies on the potential influence on the development of children failed to provide definitive evidence for or against the occurrence of neurological dysfunction. Sample heterogeneity and Reprint requests :. Dr. Shen Xiao-ming, Shanghai Institute for JPediatricResearch, Shanghai- 200 092, China. 233
inadequate assessment of lead exposure and neuropsychological function could account for discrepancies? In this study, the children were likely to have had been exposed to the same polluted environment, came from similar social backgrounds and locally standardized psychological tests were administered to assess the cognitive functions. Multivariate step-wise regression and multiple analysis of covariance were employed in order to evaluate the true
234
THE INrDIANJOURNALOF PEDIATRICS
relationship between blood lead levels and intelligence. MATERIAL AND METHODS
Subjects All the 189 children came from a day care centre in a lead-polluted area where a smeltry was located. They were enrolled in study with parental consent. The following WHO exclusion criteria 2 were applied and 46 children were excluded: (i) birthweight 0.05 > 0.05
29 29 29
87 _+ 14 90 _+ 17 86 _+ 12
52 52 52
102 _+ 11 104 _+ 12 99 _+. 12
5.1158 4.1405 4.7248
