<P> According to the 568 / 2002 law signed by the Romanian parliament and republished in 2009, since 2002 iodised salt is distributed mandatory in the whole country . It is used mandatory on the market for household consumption, in bakeries and for pregnant women . Iodised salt is optional though for animal consumption and the food industry, although widely used . The salt iodisation process has to assure a minimum of 30mg iodine / kg of salt . </P> <P> The South African government instructed that all salt for sale was to be iodised after December 12, 1995 . </P> <P> In the U.S. in the early 20th century, goitre was especially prevalent in the region around the Great Lakes and the Pacific Northwest . David Murray Cowie, a professor of paediatrics at the University of Michigan, led the U.S. to adopt the Swiss practice of adding sodium iodide or potassium iodide to table and cooking salt . On May 1, 1924, iodised salt was sold commercially in Michigan . By the fall of 1924, Morton Salt Company began distributing iodised salt nationally . There was a gradual increase in average intelligence of 1 standard deviation, 15 points, in iodine - deficient areas and 3.5 points nationally . </P> <P> A 2017 study found that the introduction of iodized salt in 1924 raised the IQ for the one - quarter of the population most deficient in iodine . These findings "can explain roughly one decade's worth of the upward trend in IQ in the United States (the Flynn effect)." The study also found "a large increase in thyroid - related deaths following the countrywide adoption of iodized salt, which affected mostly older individuals in localities with high prevalence of iodine deficiency ." </P>

When did they start putting iodine in salt