To help schoolchildren in poor countries, reduce lead poisoning

Schoolchildren in poor countries perform worse on standardised tests than those in rich ones. They also have ten times more lead in their blood. In a new working paper researchers at the Centre for Global Development (CGD), an American think-tank, argue that lead poisoning alone accounts for a fifth of the learning gap between rich and poor countries. Kids in poor countries are held back for many reasons, but the cognitive burden of lead poisoning makes learning even harder—and may be the simplest challenge to tackle.

Leaded petrol, which has been banned by every government in the world, is no longer a problem. But lead still lurks elsewhere in poor countries. Half of all children in south Asia and nearly 40% of those in Africa have elevated levels of lead in their blood. Lead exposure, which alters the release of neurotransmitters in the brain and is associated with shorter attention spans, lower intelligence and anti-social behaviour. Using a set of “harmonised learning outcomes” from the World Bank, the researchers show that the learning gap between developing countries and developed ones would shrink by 21% if lead poisoning could be brought to American levels.