Crawfurd, LeeTodd, RoryHares, SusannahSandefur, JustinBonnifield, Rachel Silverman2025-08-082025-08-082024-08-16The World Bank Research Observer0257-3032 (print)1564-6971 (online)https://hdl.handle.net/10986/43567Around half of children in low-income countries have elevated blood-lead levels, raising concerns about the role of lead exposure in explaining poor educational outcomes in these settings. This study presents a new systematic review and meta-analysis of observational research on the relationship between lead exposure and learning outcomes. After adjusting for observable confounds and publication bias, the benchmark estimate indicates a −0.12 standard-deviation reduction in learning per natural log unit of blood lead. Since all estimates are non-experimental, the paper also examines the likely impact of unobserved confounding and summarizes findings from a smaller set of natural experiments. The benchmark estimate accounts for over one-fifth of the learning gap between rich and poor countries and suggests that targeted interventions for highly exposed groups could yield moderate learning gains (approximately 0.1 standard deviations), while broader public health campaigns may result in more modest improvements (less than 0.05 standard deviations).en-USCC BY-NC-ND 3.0 IGOLEAD POISONINGCHILD EDUCATIONDEVELOPING COUNTRIESJournal ArticleWorld Bank