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Global logo for iodised salt. Logos, such as this one, are placed on salt packages to help consumers identify salt that contains added iodine.

Iodised salt (also spelt iodized salt) is table salt mixed with a minute amount of potassium iodide, sodium iodide or iodate. It is used to prevent and remedy iodine deficiency. Worldwide, iodine deficiency affects about two billion people and is the leading preventable cause of mental retardation. It also causes thyroid gland problems, specifically endemic goiter. In many countries, iodine deficiency is a major public health problem that can be cheaply addressed by iodisation of salt.

Iodine is a micronutrient that is naturally present in the food supply in many regions. However, where natural levels of iodine in the soil are low and the iodine is not taken up by vegetables, iodine added to salt provides the small but essential amount needed by humans.

[edit] Production

Edible salt can be iodised by spraying it with a potassium iodate solution. Two ounces of potassium iodate, costing about USD$1.15, are required to iodise a ton of salt.^[1] Salt is an effective vehicle for distributing iodine to the public because it does not spoil and is consumed by everyone in the population, in fairly predictable amounts.^[2]

[edit] In public health initiatives

Worldwide, iodine deficiency affects two billion people and is the leading preventable cause of mental retardation.^[1] According to public health experts, iodisation of salt may be the world's simplest and most cost-effective measure available to improve health, costing USD$0.05 per person per year.^[1] At the World Summit for Children in 1990, a goal was set to eliminate iodine deficiency by 2000. At that time, 25% of households consumed iodised salt, a proportion that increased to 66% by 2006.^[1]

Salt producers are often, although not always, supportive of government initiatives to iodise edible salt supplies. Opposition to iodisation comes from small salt producers who are concerned about the added expense, private makers of iodine pills, concerns about promoting salt intake, and unfounded rumours that iodisation causes AIDS or other illnesses.^[1] Iodisation programmes are more likely to be successful in areas where most edible salt is produced by a small number of large companies, as opposed to hundreds of smaller companies.

The United States Food and Drug Administration recommends^[3] 150 micrograms of iodine per day for both men and women.

[edit] Kazakhstan

Kazakhstan, a country in Central Asia in which local food supplies seldom contain sufficient iodine, has drastically reduced iodine deficiency through salt iodisation programmes. Campaigns by the government and non-profit organisations to educate the public about the benefits of iodised salt began in the mid 1990s, with iodisation of edible salt becoming legally mandatory in 2002.^[1]

[edit] United States

In the U.S. in the early 20th century, goiter was especially prevalent in the region around the Great Lakes and the Pacific Northwest. Goiter began receiving serious attention as a result of the World War I draft pointing to the problem in Northern Michigan and Wisconsin. At this time, many men were disqualified from military service as a result of the public health problem. This raised questions beyond the ability of these men to serve in the war. Many asked: if they could not do this, how useful were they in everyday civilian life?^[4]

David Murray Cowie pioneered the salt iodation process in America. A professor of pediatrics at the University of Michigan, Cowie was concerned about the widespread problem of goiter in Michigan (nicknamed the "goiter belt" of America). Aware of the Swiss process of adding sodium iodide or potassium iodide to table and cooking salt, Cowie decided that a simple way to address the problem of iodine deficiency would be to merely implement the Swiss solution in America. He had noted that adding iodine to aquatic environments in the Pacific Northwest seemed to decrease the incidence of goiter among fish species. Public opinion also supported his effort in that "important discoveries of vitamins and their roles in food nutrition" were happening during the period. Cowie appealed to the Michigan State Medical Society, a "productive group which concerned itself with the search for answers to difficult medical questions pertaining to the health of the state's residents".^[5]

Incorporating iodine into a regular diet would not be an easy process; the salt producers of America had to be persuaded to incorporate sodium iodide into their production process. It was difficult to prove that people who consumed iodised salt were better protected from simple goiter, a difficulty that contributed to resistance to the movement. Cowie and the Michigan State Medical Society turned to the Michigan Salt Producer's Association in 1923. Soon, an iodised salt committee was formed. After several months of meetings and deliberations with physicians and educators, the Executive Council of the Michigan State Medical Society gave Cowie the authority to endorse and implement the production of iodised salt, and the Michigan salt producers agreed to begin producing iodised table salt with labels reading "contains .01 per cent sodium iodide".^[6]

On May 1, 1924, iodised salt by Diamond Crystal Salt, Mulkey Salt, Inland Delray Salt, Michigan Salt Works, and Ruggles and Rademaker appeared on Michigan grocers' shelves. By the fall of 1924, Morton Salt Company began distributing iodised salt nationally.

Cowie's efforts to improve the public health environment necessitated broad cooperation. Cowie gained support from the medical board and market support from the Michigan Salt Producers Association, and with this scientific backing, the general public accepted the change.

Another person who is also credited for the introduction of iodised table salt to America is Dr. William A. Hudson, who devoted much of his time to the study of iodine levels in the blood while at Washington University, the Royal Victoria Hospital in Montreal, and Ford Hospital in Detroit.

[edit] See also

• History of salt
• Basil Hetzel
• Enriched flour serves an analogous function to "enriched salt."
• Water fluoridation, a similar but much more controversial public health intervention
• Iodine is a trace element, to which vitamins may be compared.

[edit] Notes

1. ^ ^{a b c d e f} McNeil, Donald G. Jr (2006-12-16). "In Raising the World’s I.Q., the Secret’s in the Salt", New York Times. Retrieved on 4 December 2008. 
2. ^ Willyard, Cassandra (June 2008). "Salt of the Earth: The public health community employs a mineral to fight infectious disease". Geotimes. American Geological Institute.. Retrieved on 2008-12-14.
3. ^ 2005 CFR Title 21, Volume 2
4. ^ Markel, When in Rains it Pours, p. 220
5. ^ Markel, When in Rains it Pours, p. 222
6. ^ Markel, When in Rains it Pours, p. 219-224

[edit] References

• Markel, Howard. (1987) When It Rains It Pours: Endemic Goiter, Iodized Salt, and David Murray Cowie MD. American Journal of Public Health, vol. 77 , pp. 219-229.
• 21 CFR 101.9 (c)(8)(iv)
• http://encyclopediaofarkansas.net/encyclopedia/entry-detail.aspx?entryID=364

[edit] External links

• Network for Sustained Elimination of Iodine Deficiency