The use of other methods of iodization such as iodized bread and iodized water has not proceeded to the mass population level but may be indicated in special situations.
Iodized Bread
Iodized bread has been used in Holland and in Australia, and detailed observations are available from the Australian island of Tasmania. Since 1949 the Tasmanian population has received iodine dietary supplements in the form of weekly tablets of potassium iodide (10 mg) given to infants, children, and pregnant women through baby health clinics, schools, and antenatal clinics whenever possible. The prevalence of endemic goiter fell progressively during the next 16 years but was not eliminated. The failure to eliminate the disease completely was traced to a lack of cooperation by a number of schools in the distribution of the iodide tablets. The distribution through the child health centers to infants and preschool children was also ineffective because of the children’s irregular attendance.
For this reason a decision was made to change the method of prophylaxis from iodide tablets to iodized bread. The use of potassium iodate up to 20 parts per million (ppm) as a bread improver was authorized by the National Health and Medical Research Council of Australia in May 1963, and the necessary legislation was passed by the Tasmanian Parliament in October 1964.
The effects of bread iodization were measured by a series of surveys of palpable goiter rates in schoolchildren. A definite decrease in the visible goiter rate was apparent by 1969. Yet studies of urinary iodide excretion and plasma inorganic iodide in May 1967 revealed no excessive intake of iodide. Correction of iodine deficiency was confirmed by evidence of a fall of 24-hour radioiodine uptake levels in hospital subjects as well as normal plasma inorganic iodine concentration and urine iodine excretion (Stewart et al. 1971).
Thus bread iodization was effective in correcting iodine deficiency in Tasmania in the 1960s. However, today there is a greater diversity of sources for dietary iodine. It is readily available from milk due to the use of iodophors in the dairy industry, and it is also available from ice cream due to the use of alginate as a thickener.
Iodized Water
Reduction in goiter rate from 61 percent to 30 percent with 79 percent of goiters showing visible reduction has been demonstrated following water iodization in Sarawak (Maberly, Eastman, and Corcoran 1981). Similar results have been obtained with preliminary studies in Thailand by Romsai Suwanik and his group at the Siriraj Hospital, Bangkok, and in Sicily (Hetzel 1989). Iodized water may be a more convenient preventive measure than iodized salt and there may be less likelihood of iodine-induced thyrotoxicosis. Certainly this method is appropriate at the village level if a specific source of drinking water can be identified.
World History
