Lead exposure in children: Levels in blood, prevalence of intoxication andrelated factors

Lead is a highly toxic metal, the main source of which is contamination fro m combustion of unleaded petrol. The aims of this work were to detect the d egree of lead exposure in a large sample of children; determine the relatio nship between blood lead levels (BPb) and age, sex, habitat and season of t he year; and correlate BPb with zinc protoporphyrin (ZPP) values. A cross-s ectional study was carried out. Blood from routine extractions drawn at our centre was used. BPb and ZPP were measured by atomic absorption spectropho tometry and haematofluorimetry, respectively. We analysed 1158 blood sample s from children. BPb (mean +/- SEM): 0.22 +/- 0.04 mu mol l(-1). Correlatio n BPb-age: BPb = 0.19 + 0.086 x age (months), r = 0.129, P < 0.0001. BPb wa s greater in boys (0.23 +/- 0.007 versus 0.20 +/- 0.006 pmol l(-1), P < 0.0 002), No differences were observed between habitats (urban versus rural). B Pb were higher in the warm months (0.24 +/- 0.013 versus 0.21 +/- 0.007 pmo l l(-1), P < 0.0001). Prevalence of lead intoxication (BPb > 0.48 mu mol l( -1)) was 4.2%. No differences in prevalence were found among the different groups. The correlation between BPb and ZPP showed r = 0.0969, P = 0.0024. Utility for screening: sensitivity of 53.7% and specificity of 59.3% (cut-o ff point of 60 mu mol ZPP mol-l haem). We can conclude that lead exposure i n children in our sample was in the range reported in similar studies in of her areas and countries, and below the toxic limit. None of the factors an alysed significantly influenced lead intoxication prevalence. There was no good correlation between ZPP and BPb in our sample and the ZPP cut-off poin t used did not present good specificity and sensitivity values.