Iodized Salt and U.S. Development

The importance of micronutrients in human development has received increasing attention both in medical science and in economic policymaking. Iodine de…ciency is one of the most discussed issues related to micronutrients in the context of less developed countries. Given that systematic evidence of the e¤ectiveness of iodine supplementation in developing countries is still lacking, my study evaluates the e¤ects of the introduction of iodized salt in the United States in 1924, thereby …lling some of this gap. Using U.S. census data and exploiting geographic variation in iodine de…ciency before 1924, as proxied by the prevalence of goiter, I …nd that the introduction of iodized salt led to improvements in schooling among children, greater income gains among adults, and better long-term economic outcomes. Many of these estimated bene…ts are attributable to postnatal exposure to iodized salt, further demonstrating the importance of iodine supplements, which had previously been demonstrated only in utero. The estimated economic bene…ts are especially impressive when contrasted with the extremely low cost of salt iodization, which is merely 2 to 9 US cents per person/year. Such cost-e¤ectiveness is of particular relevance to low-income countries, given the limited funds that are typically available for large-scale public health interventions. I am very grateful to Mark Duggan, Jeanne Lafortune, and Judy Hellerstein for their advice and support. I thank Raymond Guiteras, Soohuyng Lee, John Shea, and seminar participants at the Microeconomics Seminar Workshop at the University of Maryland for their comments. All errors remain my own.