Iodization of salt

Shen Ning, third millennium BC, Hippocrates 460-370BC, Coindet 1820, Boussin-gault, iodization of salt, Chatin 1851... 

Seaweed and sponges against goiter. 1 deficiency —> goiter, iodization of salt... 

The major end-use of iodine is in catalysis (e.g., the Monsanto process for producing acetic acid). Titanium tetraiodide and aluminum iodide are also significant in the dehydrogenation of butane and butene to butadiene, and in the preparation of stereoregular polymers. The second major end-use of iodine is as a stabilizer in the manufacture of nylon, for converting resins, tall oil and other wood products to more stable forms, while the third major use is as additives for animal and human food (iodization of salt and mineral mixtures). 

Iodi2ed salt is the most important source of iodine worldwide, and is also the agreed strategy for achieving iodine sufficiency (WHO/UNICEF/ICCIDD, 2001). Although Norway has never had mandatory iodization of salt, some brands of table salt are fortified with iodine, and regulations permit the addition of 5 pg of iodine per gram of NaCl (Ministry of Health, 2002). Industrial salt used in food production is not supplemented with iodine (Frey, 1986). 

Hazarika and Mahanta, 2004). A very worrying observation in this study was the fact that more than 90% of the heads of households neither considered goiter a health problem, nor had any knowledge of iodization of salt. 

Small producers pose an even greater challenge to educate, because their subsistence operations with small turnovers and modest profits leave little room for additional expenses such as iodization. In addition, their salt is invariably of inferior quality, making iodization less effective. Despite these potential barriers, they should share in the iodine-related information flow and have exposure to educational activities that may improve their iodine knowledge and positively influence their attitude and perspective of iodine nutrition and iodization of salt. 

In countries with voluntary or optional iodization of salt, housewives choice of iodized over noniodized salt is usually based on their perception of the greater health benefit derived from using iodized salt, if there is no price differential. In these countries, varied educational strategies are required to ensme an adequate iodine knowledge level for individuals to choose correctly if given a choice. 

Active prophylaxis (AP) is the provision of iodine supplements to an iodine-deficient population. Beside the individual supplementation of oral iodine and injections of iodized oil, the most common supplementation strategy is the iodization of salt, water and animal feed. Some countries allow only iodized salt to be sold, while other countries allow both iodized and uniodized salt. 

Since the iodization of salt, there has been an increase in the daily consumption of iodine among the population, leading to a decrease in the prevalence of iodine deficiency disorders. In a survey (Toteja et ai, 2004) carried out on 1 45 264 children aged 6—12 years in 15 districts in India in 1997—2000, the goiter rate was found to have decreased to 4.78% as compared to a previous report of 21% in 1984—1986 (IGMR, 1989). Follow-up surveys carried out in the same region of the country over the period have shown a decrease in the prevalence of goiter over the years, as exemphfied by data from the National Capital Territory of Delhi (Table 87.1). 

Iodine deficiency was common worldwide. Some countries in Europe, Asia, Africa and some states of Australia are still iodine deficient despite major national and international efforts to increase iodine intake, primarily through the voluntary or mandatory iodization of salt. 

Monitoring the iodine intake and the occmrence of thyroid disorders in the population (the DanThyr program) consisted of three main parts, all of which were started before the iodization of salt, so as to include a control period (Figure 119.2). 

With the approval of Law no. 6.150, of 3 December 1974, which provided for the mandatory iodization of salt for human consumption throughout Brazil, the responsibility for acquiring iodine and the necessary equipment was shifted to salt producers. The law maintained the lOmg/kg of salt content requirement and provided for the replacement of potassium iodide by potassium iodate, which is a much more stable compound with lower water solubility (Dantas, 1996 Brasil, 1996 Demayer et al, 1979). 

The iodine content of plant and animal foods depends on the environment in which they grow hence, the low iodine content of New Zealand soils results in low concentrations in locally produced foods (Hercus et al., 1925). Prior to iodization of salt in the 1930s, Hercus analyzed a selection of foods (Table 129.1) and estimated daily intake from these values the intake in areas where goiter was endemic was around 26 pg/day while in non-goitrous areas it was around 40 pg/day (20 and 35 pg/day respectively, if fish was not included) (Hercus and Roberts, 1927) (Table 129.2). 

In consequence to iodization of salt in the 1930s, goiter was virtually eliminated by 1953. 

The iodine status of New Zealanders was adequate from the 1960s to 1980s as a result of iodization of salt and contamination of dairy foods with iodine from the use ofiodophors. 

In 1983 salt iodization with 25 mg Kl/kg household salt was started in East Germany. In 1985, KI has been substituted by the more stable KIO3 (32 mg KI03/kg salt). The next and more successful step was iodization of mineral mixtures (18 mg KI03/kg = 11.3 mg I/kg) for pigs which was used countrywide and for cattle (only in the Southern districts). In 1991 iodization of salt in bags started with 20 mg KI03/kg. 

Thanks to a good control of the factors listed in table 1 many countries have successfully used potassium iodide (KI) for iodization of salt, but some, even when technically advanced, have encountered stability problems. In such cases it is preferable... 

In 1986 a iodization of salt started again with the theoretical concentration of 20 mg Kl/kg. During the investigations done in connection with the Chernobyl accident in different parts of Poland it... 

The data presented indicate the magnitude of the goiter endemia. To approach this problem a Polish Council for Control of Iodine Deficient Disorders ( PCC IDD ) was organized in April 1991 and a preliminary program of prophylactic measures was presented to the Ministry of Health. The PCC IDD requested the Ministry to organize the large scale iodization of salt with a concentration of 25 mg Kl/kg. With a salt consumption of about 5-10 g/day this gives a daily iodine intake of 125 - 250 ug. 

Currently the iodide used for iodization of salt is being replaced by iodate which should be completed during 1992-93. 

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