Blood lead concentrations in sub-Saharan African children below 6 years: systematic review

OBJECTIVE To assess the geometric mean of blood lead levels in children aged below 6 years living in sub-Saharan Africa. METHODS Search strategies were developed in MEDLINE, Web of Science and Google scholar system, supplemented by screening of references from included papers and review articles. Studies including children younger than 6 years residing in sub-Saharan Africa (SSA) were eligible. The studies were assessed for quality of methods for blood collection, for participants' recruitment and for quality control for lead analyses. Data were extracted and synthetised by estimating the mean weighted by sample size. RESULTS A total of 11 148 published papers were identified with only 16 studies conducted in SSA. Only nine of them were relevant of inclusion criteria. The weighted mean of blood lead levels was 13.1 mu g/dl. Five of included studies were classified as being less likely to present selection bias, having performed venipuncture and adequate quality control for lead analyses. The weighted mean from analyses involving only these studies was 16.2 mu g/dl. Six of the included studies reported the prevalence of blood lead levels >= 10 mu g/dl; levels ranged from 7.0% to 70.9%. Only one study reported the prevalence of blood lead levels >= 5 mu g/dl (50%). CONCLUSIONS The geometric mean of blood lead levels in sub-Saharan African children is still elevated relative to the US children. The new standard from the Centers for Disease Control and Prevention (5 mu g/dl) implies that important efforts should be directed towards the initiation (or reinforcement) of prevention programmes and thorough research studies in sub-Saharan Africa.