INCAP studies of endemic goiter and its prevention.

The high prevalence of goiter among adults in its member countries of Central America and Panama was observed as soon as INCAP began field studies. This led to systematic studies of goiter in schoolchildren in all of the countries as described, beginning with Guatemala where the rate was 38% nationally. However, efforts to eliminate the consequences of iodine with iodized salt using the water soluble potassium iodate and a process that had proved successful in Switzerland and the United States could not be used with the crude moist salt of the region. INCAP identified potassium iodate that is insoluble in water, and in four schools (two each in El Salvador and Guatemala) proved that the iodine in this compound was as available as that in potassium iodate. It remained evenly distributed in moist salt. When added to salt in Guatemala, goiter rate dropped to 15% in four years and less than 5% in eight years. Compulsory iodation of salt in other developing countries followed with comparable results. This method is now used in worldwide campaigns against iodine deficiency in developing countries.