FOLLOWING THE DEMONSTRATION (1) that colloid goiter could be prevented or cured by use of small doses of iodine given during childhood and adolescence there arose a suspicion that universal use of iodine by the population in the ‘goiter belt’ might be dangerous. This was because of fear that an induced thyrotoxicosis would follow (2) in a significant number of adults. This fear has been dispelled in most quarters (3, 4) by the experience of the past quarter century. During this time iodine has been used on personal prescription, administered in tablet form to school children in large groups, and has been made available to the entire population of certain urban areas by iodization of water supplies. The most popular form of iodine supply has become the iodized table salt which is now provided by most manufacturers of salt as an alternate form of boxed or bag salt. Two further criticisms of this form of iodine supply have been expressed, that the iodine content of such salt may be variable and unstable (5) ...