ASSESSMENT OF LEAD EXPOSURE AMONG CHILDREN IN SELECTED NURSERY SCHOOLS IN LAGOS METROPOLIS, NIGERIA

Abstract

Lead in the environment comes from paints, petroleum, solder and through various routes such as water, food, air, dust and soil. Children of pre-school age are more exposed to these environmental hazards due to their habits of licking fingers, chewing objects or actually eating contaminated dust, soil and food items. This study was undertaken to assess the sources of lead exposure among children in selected Nursery Schools in Lagos Metropolis. The study was exploratory in nature. For sampling, Lagos Metropolitan schools were divided into three zones as low (Victoria Island), medium (Mile ii) and high density (Ojo) areas reflecting various socio-geographical factors and a school was selected in each zone based on simple random method. A random sampling method was employed in selecting the subjects and collecting environmental samples. A total of 150 children comprising of 77 (51.3%) boys and 73 (48.3%) girls. Two hundred and seven (207) different samples were analyzed, 150 hand washings from 150 children. Twenty six (26) toy washings which comprises of various toys such as balls, telephone, empty beverage tins, cars ranging in diameter from 30cm x 15cm to 5cm x 4cm, 9 soil samples, 9 classroom sweepings, 9 roof top water and 4 eye based cosmetic samples.

Lead and other physical-chemical characteristics of the samples were determined viz pH value, Total Dissolved Solids (TDS), Total Suspended Solids (TSS), Turbidity (FTU) and Conductivity (ms/cm) using standard methods as recommended by American Public Health Association (1998). The mean lead levels of the boys in low, medium and high-density areas were as follows: 0.232± 0. 106mg/hand, 0.044 ± 0.037mg/hand and 0.093 ± 0.076 mg/hand, while that of the girl was 0.126 ± 0.089 mg/hand, 0.036 ± 0.027 mg/hand and 0.070 ±0.070 mg,/hand. A positive statistically significant correlation was found between lead in the hand washings and other physical parameters Lead and to (r = 0.4 p =0.00), lead and TSS, (r = 0.5. p =0.0), Lead and conductivity (r = 0.6. p = 0), lead and TM (r = 0.6, p T 0.0). The man lead values or the toy washings in the low, medium and high density areas were as follows 0.07 ± 0.03 mg/toy and 0.056 ±0.04mg/toy. A statically significant linear correlation was found between lead in toy washings and other physical parameter (r=0.05). There was no significant association between lead and pH (r=0.03 p<0.05). The lead levels in classroom sweeping ranged between 180-615 mg/kg which is above the WHO recommended level of indoor lead of 200 mg/kg. The lead level in the playground samples ranged from 945-3602mg/kg with a mean of 1962 ± 49mg/kg. These observations indicated that the lead levels of the soils were above the Federal Environmental Protection Agency (FEPA) permission limit of 500mg/kg. The lead levels in the roof top water in the three-study area ranged from 0.05-0.25mg/l with a mean of 0.124 ± 0.02mg/l, which is above the WHO, recommended value of 0.01 mg/l of drinking water. The cosmetics samples showed lead levels in the range of 0.19 - 5.76 ug/g and a mean of 2.95 ug/g. The in-depth interview revealed that the level of awareness of the various sources of lead in the environment and its associated health hazards was low among the respondents. Based on these results, the lead levels in school environment is due to lead content from dirt (possibly from automobile emissions) on the children's hands, toys, soil and cosmetics. This study shows that children are unduly exposed to lead from their immediate environment. There is need to control lead levels through legislation and health education.