

"Salt Iodization and the Enfranchisement of the American Worker" - gwern
http://www.elon.edu/docs/e-web/academics/business/economics/faculty/bednar/MortonSalt_body_aug2013.pdf

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gwern
> 'We study the economic consequences of the rapid nationwide introduction of
> iodized salt in the United States. In 1924, Morton Salt Co., the largest
> salt producer in the US, decided to iodize its salt supply. Through the
> proliferation of fortified salt, access to iodine, a key determinant of
> cognitive ability, increased intelligence quotients in areas where
> deficiency rates were previously high. We compare outcomes for cohorts
> exposed in utero to iodized salt to slightly older, unexposed cohorts,
> across individuals born in states with previously high versus low iodine
> deficiency rates. We find substantial impacts of salt iodization. High
> school completion rose by 6 percentage points, and labor force participation
> went up by 1 point. Analysis of income transitions by quantile shows that
> the new labor force joiners entered at the bottom of the wage distribution
> and took up blue collar labor, pulling down average wage income conditional
> on employment. Our results inform the ongoing debate on salt iodization in
> many low-income countries. We show that large-scale iodized salt
> distribution had a targeted impact, benefiting the worker on the margin of
> employment, and generating sizeable economic returns at low cost.'

