Variations of Concentrations of Lead, Zinc, Iron, Copper and Cadmium in Urine of Primary School Pupils in Relation to Age, Sex and Academic Performance

Abstract

This study was conducted in order to assess the variations and correlations in the concentrations of lead, zinc, iron, copper and cadmium metals in the urine samples of selected primary school pupils with respect to their sex, age and academic performance. Urine samples were collected from 240 pupils in Dar es Salaam, Tanzania and then digested in concentrated acids and analysed using atomic absorption spectrometry (AAS). Lead, zinc, iron and copper were detected in most of the urine samples. Cadmium was not detected in any of the samples. The mean concentrations of lead, zinc, iron and copper in the samples from different classes ranged between 0.27–0.90, 0.59–0.78, 1.56–2.32 and 0.005–0.01 mg/L, respectively in pupils with high academic performance, and 0.37–0.71, 0.56–0.81, 1.79–2.55 and 0.005–0.01 mg/L, respectively in pupils with low performance. The overall mean concentrations of the metals ranged between 0.01–2.04 and 0.01–2.17 mg/L in males and females, respectively. There were no significant differences in most of the concentrations of the heavy metals in pupils’ urine samples between the two sexes. The findings indicated some significant positive correlations between the pupils’ age and the concentrations of lead and iron in urine samples, while there were no significant correlations for zinc and copper. Some of the concentrations of the heavy metals showed significant negative or positive correlations with the academic performance of the pupils. Therefore, the concentrations of the heavy metals were correlated with age, sex and academic performance in some samples. The concentrations of lead were generally alarming.

Keywords: Heavy metals; children urine; age; sex; academic performance; Tanzania