Search continues for causes of lead toxicity in Nigeria

Combating lead toxicity in children in developing countries seems a distant prospect with the failure of a study to identify the main causes of exposure in urban Nigerian children with high lead concentrations in their bloodstream.

Multivariate analysis confirmed a link between a range of variables and high blood lead concentrations in two mostly Muslim administrative wards in Jos, Nigeria, one with a population with high amounts of lead in the bloodstream and one whose population had lower amounts. These were age ≤5 years; male sex; chipped (lead based) paint in the home; a nearby outfit selling gasoline or a nearby battery smelter; cosmetic use of lead ore eye pencils in children; and, rather surprisingly, parental education. Together they accounted for just 38% of total variance. Living in the “high lead” ward remained significantly related to raised blood lead, suggesting a residual cause not already accounted for. Among adults and children with complete data from 34 households, 137 lived in the high lead (mean blood concentration 37 (SD13) mg/l) and 138 in the low lead (mean 17 (10) mg/l) ward; 92 (34%) had values ≥10mg/l.

Adults and children were questioned about sources of exposure, and lead in the blood was measured from blood spot samples taken from a washed finger.

Seventy per cent of children aged 6–35 months in Jos have raised blood lead concentrations. Lowering lead exposure is a key step in reducing its toxic effects on cognitive development, especially in children, combined with calcium, iron, and vitamin C supplements in developing countries.