Estimation of lead in urine of school children in south western Nigeria and effect of ascorbic intervention

Abstract

This study was carried out to investigate the level of lead in the air and urine of pupils in selected schools in south western Nigeria and ascertain the effect of ascorbic acid, with a view to providing baseline data on lead levels in children. A total of 197 pupils in schools in urban and rural communities of Ife Central Local Government, Osun State in the south west of Nigeria (that is Sabo, Iremo and Ajebamidele (n = 119) and Kajola and Abagboro (n = 78), respectively), The pupils in both communities were randomised into experimental and control group, the experimental group were placed on 500 mg of ascorbic acid daily for five days. Urine samples were collected on the first, third and fifth day of the study from the pupils in experimental and control groups and analysed for lead using Atomic Absorption Spectrophotometer. Air samples were collected using the LaMotte air sampling pump and analysed for lead using the same method. The cross sectional survey indicated that the mean lead levels in the air in the school environment in the urban communities on the first, third and fifth day of the study were (8.69 ± 0.070, 9.27 ± 0.09 and 9.27 ± 0.09 µg/m³) respectively and significantly higher than lead levels in rural communities (3.73 ± 0.030 µg/m³). The lead concentration in the urine of the pupils in experimental group in urban (5.51 ± 1.07 µg/m³) and rural communities (5.27 ± 0.98 µg/m³) were similar on the first day of the study. The ingestion of ascorbic acid increased excretion of lead in the urine of pupils significantly (11.22 ± 1.48 µg/m³) on the third day and decreased marginally on the fifth day (9.87 ± 1.20 µg/m³) in the urban communities. Similarly in the rural communities there was a significant increase (11.52 ± 1.41 µg/m³) in the excretion of lead in the urine of pupils on the third day but a marginal increase on the fifth day (12.88 ± 2.27 µg/m³) of the ascorbic acid ingestion. The lead level in the air on the first day of the study had no linear relationship with urinary lead level in the urban and rural communities whilst on the third and fifth day of the study, a linear relationship was observed between lead levels in the air and urinary lead levels of the pupils in the urban and rural communities. Key words: Urinary lead levels, air lead levels, school children, ascorbic acid intervention