Intelligence quotient level of the children living in high lead areas in Zanjan province

Background and Objectives : Considering the effect of heavy metals (particularly lead) on intelligent quotient level , It was measured in children living in high lead areas in Angouran district of Zanjan province .

Material and Methods : In this historical cohort study all( n=64 ) grade – one students living in Angouran village were selected as case group. 62 other students living in low lead areas , but with similar socio – economic , cultural and racial conditions were selected as the control group. In a double blind study using the wechler’s intelligence scale for children – revised ( WISC-R) the IQ level of both groups were  calculated . This test is regarded as the most accurate test with 80-90% reliability . The IQ of 90 or more is considered normal and less than this is low. By using chi-square the IQ of the two groups living in high and low – lead areas were compared . The T-test and P- value with 95% reliability and the relative risk of decrease of IQ due to living in high – lead areas were calculated .

Results :The average IQ level in 64 children living in high lead area was 86.64+/-9.68 with 40 ( 62.5% ) having less than normal level. In comparison in the other group the average IQ level was 91.98+/-10.26 with 24 of the children (38.7%)having less than normal level . The IQ level in children living in high-lead area was significantly lower than children living in low- lead area( P<0.0031 ).

Discussion: Although the serum level of lead was not determined but the results of this study are strongly in favor of the relationship between living in high-lead areas and low IQ levels. Preventive and therapeutic precautions are necessary in theses areas.