Environmental lead exposure and its correlation with intelligence quotient level in children

Abstract

Background: Lead (Pb) is ubiquitous, naturally occurring heavy metal that has a neurotoxic effect on the CNS and causes a range of health problems in humans, including cognitive impairment. Its toxicity remains a worldwide health issue, especially in developing countries. In this study, we tend to investigate the relationship between Pb poisoning and sociodemographic status, intellectual and neurobehavioral capabilities of children.

Methods: The background characteristics of the research subjects were collected via questionnaire. The study involved 43 children, aged from 4 to 12 years. Blood lead (BL) levels were analysed by using anodic stripping voltammeter (ASV). Intelligence quotient (IQ) was another parameter that was assessed via using the Goodenough draw-A-person test in Pb exposed as well as control children. Although sociodemographic information was obtained in a questionnaire pattern from the parents.

Results: The mean of BL level was 19.93 ± 9.22 μg/dL. BL levels were considerably higher with low social status (p < 0.05), maternal employment (p < 0.001) and the maximum time spent outdoors (p < 0.001). Source of water, age of subjects, type of house and kohl used by children was observed to be significantly correlated with BL levels i.e. (p < 0.05). IQ levels were decreased in a concentration dependent manner (p < 0.01). Negative correlations were found between BL levels and IQ levels (r = -0.963, <0.01). Girls were found to be higher IQ level than boys (p < 0.05). Moreover, higher socioeconomic status had a higher IQ level (p < 0.01) as compared to low.

Conclusion: BL levels were significantly associated with IQ levels. Sociodemographic characteristic was also found to be one of the risk factors that influenced the BL levels of children. Our investigations have demonstrated that the exposure of Pb severely affected the learning with memory, and the intelligence quotient of children, that is found inversely proportional in respect to BL levels.

Keywords: Cognitive impairment; Intelligence quotient; Lead; Neurobehavioral capabilities; Sociodemographic characteristic.