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Household coverage with iodized salt
This indicator describes the percentage of households in a country (or other defined geographic area) with iodized salt at any iodine concentration and what percentage has salt with an iodine concentration ≥15 ppm.
Understanding household coverage of iodized salt is a key performance indicator of a programme’s success. This indicator describes what is actually used in households on a national basis and provides important information about the successful delivery of iodized salt to the consumer as well as about use of non-iodized salt and inadequately iodized salt. Ideally, a goal of the salt iodization programme is that the percentage of food-grade salt with iodine content of ≥15 ppm in a representative sample of households is >90% as determined by rapid test kits and by titration in at least a sub-sample (or by only titration in the entire sample) (1).
These data provide a basis for targeting resources and focusing interventions in areas where they are most needed. Monitoring at this level should be followed by specific action to identify further reasons for non-iodized salt usage, and should result in a range of actions to correct the problem. Salt iodization levels should fall between 15 and 40 ppm at the household level according to international standards while national standards might vary slightly from these limits. Household surveys may also identify problems with iodization levels that are too high and also need to be addressed.
Household coverage of adequately iodized salt:
The numerator is the number of household salt samples collected in the survey with an iodine concentration of ≥15 ppm.
The denominator is the total number of household salt samples collected in the survey.
Divide the numerator by the denominator. Multiply the result by 100 to convert the number into a percentage.
Household coverage of iodized salt:
The numerator is the number of household salt samples collected in the survey with any iodine (>0 ppm).
The denominator is the total number of household salt samples collected in the survey.
Divide the numerator by the denominator. Multiply the result by 100 to convert the number into a percentage.
Considerations for the calculation:
a) The target of the salt iodization programme is that the percentage of food-grade salt with iodine content of ≥15 ppm in a representative sample of households is >90% as determined by rapid test kits and by titration in a sub-sample, or by titration in the entire sample.
b) Where rapid test kits are used alone, it will only be possible to report on the proportion of households using salt with any iodine, and not the proportion using adequately iodized salt.
Household salt, iodine concentration, household survey
Dietary modification
Outcome
Presence (coverage) in household or facility
All
Early childhood development, Emergency setting or displaced population, Lactation, Pregnancy
Iodine
Market-based
Household level monitoring methods are described in Chapter 5 of the WHO, ICCIDD, UNICEF 2007 publication ‘Assessment of iodine deficiency disorders and monitoring their elimination: a guide for programme managers’ – 3rd ed (1). Household monitoring is usually done through surveys or other community- based methods. Questions on iodized salt use and salt testing have been included in the UNICEF Multiple Indicator Cluster Surveys (MICS) (2) and in the Demographic and Health Surveys (3). Some countries have successfully added household salt testing to other national surveys, such as nutrition surveys or surveys that collect key economic and census data.
The ability of the rapid test kits to distinguish iodized salt from adequately iodized salt is limited, and iodometric titration is recommended for at least a sub-sample of salt samples used in monitoring at the household level when using rapid test kits. All laboratories performing iodometric titration should have clearly defined internal quality control procedures in place, and should be opened to external audit. If only rapid test kits are used without titration, then only the proportion of households using salt with any iodine is reported and not the proportion using adequately iodized salt (≥15 ppm). Iodization may be carried out using potassium iodide or iodate or sodium iodate or iodide and it is important to ensure the method selected is appropriate for the compound.
Having 90% or more households in a country using adequately iodized salt is a key target for programmes and one of the main indicators of successful iodization programmes. These indicators are noninvasive and can provide immediate results.
It does not take into account other potential dietary sources of iodine in the household, including iodine or iodized salt used in processed foods and drinking water. Carrying out population based surveys require expertise and costs that might limit the ability to collect this indicator.
A country mandated universal salt iodization (USI) including all salt for human consumption and animal feed. Potassium iodate is added at a level of fortification of 40 ± 15 ppm at the factory level. The use and adequacy of iodized salt in households was monitored three times during the last ten years, in 2001, 2005 and 2010-11. In 2001, a rapid household survey was conducted in five provinces of the country and in the capitol city. The survey design was based on 30 clusters of 30 households each. Household salt (n=900) samples were tested for iodine by rapid test kits. A total of 77.3% of the household salt samples were iodized and 22.7% of all household salt tested had not been iodized. The iodine content was re-measured by titration in a subsample (n=501) of the household samples where the salt was found iodized by the rapid test kit. The average iodine concentration in household salt analyzed by titration was 32.7 ppm (range 15-53 ppm). Overall, 62% of the samples fell between 30 and 50 ppm, confirming adherence with current legislation. The proportions of samples with iodine content <20 ppm or >50 ppm were small, 4% and 2%, respectively. In 2005, a nationally representative household survey reported 92% of samples to be adequately iodized (≥15 ppm) based on titration, which is above the international target of >90% of households with adequately iodized salt. No iodine was detected in 0.3% of the household samples. The 2010-11 survey tested 14, 894 households with the rapid test kit. In the majority of households (85.4%), salt used for cooking was found to contain iodine.
For this indicator (household coverage with iodized salt), while the 2005 survey results showed the country met the international targets for household coverage of iodized salt, the 2010-11 survey showed a small decline in household coverage falling below the international target of 90% or more, and it did not include a subsample with titration.
1. WHO/UNICEF/ICCIDD. Assessment of iodine deficiency disorders and monitoring their elimination. A guide for programme managers, third edition. Geneva: World Health Organization; 2007 (http://whqlibdoc.who.int/publications/2007/9789241595827_eng.pdf, accessed 28 January 2015).
2. Multiple Indicator Cluster Survey (MICS). In: UNICEF/Statistics and monitoring [website]. New York: United Nations Children’s Fund; 2014 (http://www.childinfo.org/mics.html, accessed 28 January 2015).
3. Nutrition. In: The DHS Program. Demographic and Health Surveys [website]. Rockville: ICF International; 2015 (http://dhsprogram.com/Topics/Nutrition.cfm, accessed 28 January 2015).