Relationship between Blood Lead Concentration and Neurobehavioral Function of Children

Park, Kwang Seub; Park, Jae Yong; Sakong, Joon

Abstract

OBJECTIVES
To evaluate effects of lead on the central nervous system of children by measuring blood lead concentration, computerized neurobehavioral function and intelligence of elementary school students.
METHODS
The study was conducted with 208 elementary school students living in the vicinity of Pohang Industrial Complex in October and November, 2005. Data on demographic characteristics, living environments and lifestyle habits were collected from subjects.
RESULTS
Blood lead levels of elementary school students ranged from 0.76-4.97 microg/dl, which is below the 10 microg/dl recommended level of CDC. The blood lead levels were similar with those reported in other domestic and international studies. Neurobehavioral tests revealed that most third grade students reacted slowly and their speed declined in simple reaction time (p<0.05), choice reaction time (p<0.05), symbol digit substitution (p<0.01), finger tapping speed nondominant hand (p<0.05) as blood lead levels increased. Sixth grade students demonstrated significance in test performance, and displayed blood lead levels of 2.00-4.00 microg/dl. Results of intelligence testing showed significantly low performance in IQ (p<0.05), vocabulary ability (p<0.05), reasoning ability (p<0.05), mathematical ability (p<0.05) and perception ability (p<0.05) among third grade students who displayed high levels of blood lead concentration. Sixth grade students showed significantly low performance in vocabulary ability (p<0.05) at high level of blood lead concentration. The difference in mean IQ scores between the group with blood lead level of < or =2.00 microg/dl and the group with blood lead level > or =3.00 microg/ dl was 3.21 in third grade students and 4.28 in sixth grade students. Low academic achievement was observed among third grade students (p<0.05) and six grade students (p<0.05) as the average blood lead level increased. Correlation analysis on the association of blood lead concentration with neurobehavioral tests revealed a positive correlation between blood lead levels and reaction time of choice reaction time and symbol digit substitution in third grade students. A positive correlation was observed between blood lead levels and reaction time of symbol digit substitution and finger tapping speed in sixth grade students. There was a negative correlation between blood lead levels and reasoning ability of third grade students (r=-0.247) and vocabulary ability of six grade students (r=-0.255).
CONCLUSION
There have been few studies on the effects of blood lead on the central nervous systems of children in Korea. The study supports the findings of earlier studies that blood lead has an impact on children. However, the study did not confirm significant association of blood lead concentration with each neurological and motor test conducted for this study due to a small sample size and relatively low blood lead levels of elementary school students. Further studies using a similar assessment methods would be helpful to evaluate the effects of low blood lead levels on the central nervous systems of children.