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Lead is abundant and, when ingested or inhaled, harmful, especially to children. While leaded gasoline is now banned across the globe, lead-acid batteries are an integral part of most road vehicles. It can also be found in pigments, paints, ammunition, toys, and more. Lead pipes, or even pipes soldered together with lead, can also deliver the toxic metal to people. The health impacts of lead are many and well-documented, but a new paper examines if exposure to lead is enough to explain massive differences in educational attainment across the globe.
In “How Much Would Reducing Lead Exposure Improve Children’s Learning in the Developing World?,” authors Lee Crawfurd, Rory Todd, Susannah Hares, Justin Sandefur, and Rachel Silverman look to establish a connection between blood lead levels and performance on IQ tests, as well as standardized tests.
The impact of eliminating lead exposure, especially to children, could have outsized returns for literacy and numeracy, especially in poor countries.
“In a simple model of global learning gaps, this effect size is sufficient to suggest that observed lead levels explain over half of the gap in learning outcomes between developing and developed countries,” write the authors before caveating that reality is more complex than simple models.
Still, the overall effect of lead on test scores is staggering, and the impact of eliminating lead exposure, especially to children, could have outsized returns for literacy and numeracy, especially in poor countries. The researchers examined observed blood lead levels (measured in micrograms per deciliter or 0.5μg/dL) as compared to the World Bank’s Harmonized Learning Outcomes score.
“As an example, the lowest scoring country, the Democratic Republic of Congo, lies 250 points below the global mean of 500, and reducing BLL to 0.5μg/dL would improve scores by 29 points,” write the authors. “On average for these 34 countries, reducing BLL to US levels improves learning by 23 points, equivalent to 21 percent of the 110 point learning gap to the global benchmark of 500 points on the World Bank scale.”
Such sizable gaps suggest even a modest reduction in lead exposure could be meaningful and have a massive return on investment. The end of leaded gasoline also helps. Other actions include cleanup of deeply polluted sites, soil remediation, household cleaning, paint remediation, and the end of leaded pipes. Some of these interventions have already yielded results, like lead paint remediation in the United States and soil capping in Bangladesh.
“Targeted environmental interventions, such as soil remediation in highly polluted areas, have shown large reductions in blood lead levels. However, such interventions are costly and we have limited evidence from developing countries,” write the authors in a companion blog post. “Educational interventions, such as providing information and advice to parents on reducing lead exposure, have led to reasonable reductions in blood lead levels in some countries. Medical interventions, particularly calcium supplementation, have also shown promising results in some contexts.”
Rather than treat this kind of intervention as pie-in-the-sky, the authors point to the successful elimination of lead from high-income countries and conclude, “It’s been done. It’s fairly cheap. And a handful of simple policies could go part way to closing the learning gaps between rich and poor countries.”