I estimate productivity gains from iodine deficiency eradication. I look at the historical experience of Switzerland and the United States, where iodine deficiency was endemic in certain regions, due to their geography. Iodine deficiency was eradicated in the 1920s by providing iodized salt to the population. I use microdata from the 1970 Swiss Census, combined with data on the pre-existing variation of iodine deficiency, and data on the market penetration of iodized salt. I merge this data with information on occupational characteristics. I find that iodization increased the probability of graduating from secondary and tertiary education by around 1 percentage point. The effect is bigger for females, where iodization explains 9-14% of the total change in graduation rates from upper education levels over this period. I also find that cohorts born in previously highly-deficient areas after the introduction of iodized salt self-selected into higher-paying occupations. Furthermore, the characteristics of occupations in those areas changed, and cohorts born after iodization selected into occupations with higher cognitive demands, whereas they opted out of physical-labor-intensive occupations. My results on occupational choice are driven by the effect of iodization on males. In joint work with Professors David N. Weil and James Feyrer, we study the effects of salt iodization in the United States in 1924. We document that right after iodized salt was introduced, there was a spike in thyroid-related deaths, centered on older-age groups and particularly affecting older females. We use data compiled during the WWI draft, which document the geographic variation in underlying iodine deficiency across US localities. We combine that data with military data from the WWII draft, and present evidence that the Air Corps received preferential treatment in its choice of recruits. By treating assignment into the Air Corps as a proxy for above-average cognitive ability, we find that the probability of assignment to the Air Corps jumps by 4-6 percentage points for those born after iodization in highly deficient areas. In a falsification exercise, we find no evidence of such a jump in the case of other disorders.
Politi, Dimitra,
"The Economic Effects of Micronutrient Deficiencies: The case of iodine."
(2009).
Economics Theses and Dissertations.
Brown Digital Repository. Brown University Library.
https://doi.org/10.7301/Z03J3B7X
