In the mid-1990s, it was estimated that the inhabitants of 130 countries were at risk of iodine-deficiency disorders (IDD)( 1 ). This number has been reducing steadily over the years, to only nineteen in 2016( 2 ). This significant reduction in iodine deficiency has been achieved through universal salt iodization (USI), which is recommended as a safe and sustainable strategy to eliminate IDD( 3 ). The proportion of households consuming iodized salt globally has increased from less than 20 % in the early 1990s( 4 ) to 75 % today( 5 ). Salt iodization has been recognized as a global public health success story( 1 ) and one of the most cost-effective nutrition interventions, with a benefit:cost ratio of the order of 30:1( Reference Horton, Alderman and Rivera 6 ). The WHO recently published a comprehensive systematic review of the effects of salt iodization( Reference Aburto, Abudou and Candeias 7 ) and guidelines on salt iodization, recommending that all food-grade (edible) salt, which is used in households and for food processing, be fortified with iodine for the prevention and control of IDD( 8 ). There is global consensus that strategies for salt reduction and USI are compatible( 9 ).
The importance of legislation for salt iodization, in particular mandatory legislation, has been recognized( Reference Gautam 10 , Reference Hoogendoom, Luthringer and Parvanta 11 ). A database maintained by the Iodine Global Network (IGN) indicates that 130 out of 197 countries have mandatory legislation for the iodization of at least household/table salt or salt for food processing( 2 ). In 2008, UNICEF estimated that globally fifty-five out of 117 low- and middle-income countries had some form of legislation( 12 ). Countries with supportive legislation have shown a greater improvement in household coverage of iodized salt in the last decade: from 49 to 72 % compared with 40 to 49 % in those without legislation( Reference Gautam 10 ). The present paper reports on findings of a review undertaken among Asian and Pacific Island countriesFootnote * on their salt iodization legislation and its impact on USI programme achievements.
Methods
We collected and reviewed draft and existing legislation, relevant programme documentation and policy papers on salt iodization from thirty-six countries in Asia. English translations of the abovementioned documents were obtained from UNICEF country offices in the countries listed in Table 1 in 2012 and updates were requested in 2015/16. An additional search was conducted of the WHO-hosted Global Database of Implementation of Nutrition Actions (GINA) and through WHO regional offices. Key parameters were extracted for analysis from the documents: name, year and nature of legislation, mandatory or voluntary, objective, scope, and whether the salt iodization standard is in the legislation or a separate regulation. Implementation details given in the legislation or supporting documents, such as coordination and enforcement authority, labelling/packaging requirements, internal and external regulatory monitoring requirements, and penalties, were also reviewed. If the country legislation specifies salt for human and animal use, and does not mention exclusion of salt for food processing, it was assumed that the country had USI. Basic information on the current status of the countries’ salt iodization programmes and household consumption of iodized salt data was sought from global WHO, UNICEF and IGN databases and country programme documents.
Table 1 Basic information on iodized salt legislation in the thirty-six countries reviewed
IDD, iodine-deficiency disorders; USI, universal salt iodization; P, production; R, retail; H, household; W, warehouse.
Results
Key information on the status of salt iodization legislation in the reviewed countries is shown in Table 1.
Existence of legislation
Out of the thirty-six countries reviewed, twenty-one had salt iodization legislation, eighteen mandatory. Legislation was voluntary in Brunei and Singapore where a standard for iodized salt is available but it does not apply to all salt. Legislation was also voluntary in Vietnam at the time the review started, although Vietnam passed new legislation on 28 January 2016 that reinstated mandatory salt iodization, effective as of March 2017( 13 ).
Draft legislation
Nine countries currently have draft legislation. These include seven Pacific Island countries that have draft Food (Safety/Control) Standards which include iodine requirements in salt.Footnote † Pakistan has draft national legislation dated 2009 that is awaiting endorsement. The endorsement process has stalled since the power of the Ministry of Health was devolved to the provinces in 2011. In the absence of national legislation, several states and territories have passed their own legislation.Footnote ‡ Timor Leste has draft national legislation dated 2010; limited efforts have taken place since it was drafted to enact it.
Bangladesh, Lao People’s Democratic Republic (Lao PDR), Malaysia and Myanmar are revising or updating their legislation. However, drafts of the new legislation were not made available. It should be noted that while the existence of or plans for revised legislation from several countries was noted in 2012, the situation remained unchanged when the review was updated in 2015/16. In Malaysia, however, the Ministry of Health has advised that nationwide mandatory salt iodization legislation is in the final stages of government approval.Footnote §
Countries without legislation
Six of the thirty-six countries had no existing or draft legislation (Table 1). Although Bhutan does not currently have official legislation for salt iodization, in 1984, the National Assembly (Parliament) banned the importation of non-iodized salt and commissioned the establishment of a salt iodization plant as a joint venture between a private firm and the government (Bhutan Salt Enterprise). All salt is imported into Bhutan already packed and iodized, primarily from India. Inadequately iodized salt is iodized by Bhutan Salt Enterprise.Footnote ‖ In the Democratic People’s Republic of Korea (DPRK), there is no legislation for salt iodization although the government has a policy to produce iodized salt and the State Planning Committee has a plan to amend an existing Salt Law to include requirements to produce sufficient iodized salt to meet national needs.Footnote ¶ The Maldives does not currently have legislation. All salt is imported and the planned focus is on strengthening the quality assurance of imported salt.Footnote **
When legislation was passed
Bangladesh was the first country in Asia to pass national legislation in 1989.Footnote †† Most countries passed their legislation in the 1990s, following the 1990 World Summit for Children which established the goal of virtual elimination of IDD( 14 ) and the 1994 recommendation of WHO and UNICEF for USI( 3 ). Cambodia, Mongolia, Afghanistan and the Solomon Islands passed legislation as late as the 2000s and Kiribati only in 2016. On the other hand, Afghanistan, India, Thailand and Vietnam have already updated their initial legislation; Vietnam issued its third salt iodization legislation at the start of 2016.
Nature of legislation
The thirty countries with draft and existing legislation have utilized different mechanisms to legislate for iodization of salt. The majority (seventeen) have developed mandatory standards or regulations for iodized salt under their Food (Safety) Act/Law. Most of these countries simply amended their salt standard/technical regulation for ‘food-grade salt’ or ‘edible salt’ to specify the iodine content, in addition to other existing criteria such as purity or moisture. For example, in Papua New Guinea, the legislation provides the following specifications for salt:
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(a) ‘is sodium chloride, free from dirt; and
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(b) shall contain, on a water-free basis and –
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I. not more than 1 % of sulphates; and
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II. not more than 0·1 % of matter insoluble …
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III. not more, in total of 0·5 % calcium and magnesium chlorides; and
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(c) shall be iodized.’
Three of the seventeen countries with salt iodization legislation under their Food (Safety) Act/Law have enacted more detailed regulations than a mandatory standard for iodized salt, such as Sri Lanka’s ‘Iodization of Salt Regulation’ and India’s ‘Prohibition and Restrictions on Sales Regulations’ that place restrictions on the sale of common salt unless it is iodized. Malaysia has also placed restrictions on sale of non-iodized salt in two states in its Food Act.
Two countries have developed a regulation under an alternative Act/Law; Afghanistan issued a regulation on iodizing salt under its Health Law and Myanmar issued a notification under its Salt Enterprise Law.
The remaining eleven countries with existing or draft legislation for salt iodization have issued a separate, stand-alone law or equivalent. For example, Indonesia issued a Presidential Decree on ‘Supply of Iodized Salt’, Lao PDR issued the ‘Prime Minister’s Legislation on Salt Iodization’, the Philippines issued ‘An Act Promoting Salt Iodization Nationwide and for Related Purposes’ and Mongolia issued the ‘Law of Mongolia – Salt Iodization and Prevention of Iodine Deficiency’. Such legislation usually has a number of supportive regulations, guidelines or implementing rules that detail how the legislation should be implemented.
Objective of legislation
Although all salt iodization legislation requires the iodization of salt, existing legislation has three different objectives: (i) non-iodized salt is banned or only iodized salt is allowed; (ii) all salt within the scope of the legislation should be iodized as per national standards; and (iii) guides the production of iodized salt but allows non-iodized salt to be produced. The different objectives guide how the legislation is enforced. Enforcement of legislation with the first objective is focused on identifying and removing non-iodized salt whereas under the second objective, the focus is on ensuring all salt is iodized as per national standards. In many countries where the legislation refers to the iodization of all salt, the focus of enforcement is on controlling the registration of salt producers and ensuring production of quality iodized salt, rather than just ensuring that all salt, regardless of who makes it or its quality, is iodized. In the third category, the legislation guides the iodization of salt, for example who can produce it, but does not emphasize that all salt within the scope of the legislation must be iodized. Of the thirty countries with existing and draft legislation, twenty ban non-iodized salt or allow only iodized salt (first objective), six require all salt to be iodized (second objective) and four guide iodized salt production but do not ban non-iodized salt (third objective). The latter category includes the three countries with voluntary legislation.
Scope of legislation
USI refers to ‘the iodization of all human and livestock salt, including salt used in the food industry’( 18 ). Recent, updated WHO guidelines for the fortification of food-grade salt with iodine emphasize the importance of fortifying salt in food processing( 8 ).
A total of thirteen of twenty-one countries with existing legislation have universal salt iodization by the above definition. Of the thirteen countries with universal scope, six specifically mention the inclusion of the salt for food processing. Remaining countries (eight) exclude either salt for food processing or for animal consumption from existing legislation. Bangladesh specifically excludes salt for food processing and legislation for Indonesia is ambiguous; some documents include it while others do not. Salt for livestock is specifically excluded from the scope of the legislation in Malaysia, Mongolia and Sri Lanka. Indian legislation excludes salt for both food processing and livestock.
The iodization of all salt for human and animal consumption, including salt for food processing, is recommended in order to ensure that all salt is iodized and that iodine intakes are adequate( 8 , 15 ). An increasing amount of salt is consumed as salt in processed foods( 16 ). If this salt is not iodized, it is possible that iodine consumption will be insufficient to achieve adequate iodine intake levels. Animal salt should be iodized because the health and productivity of animals is enhanced by adequate iodine intakes( 17 ) and animal products, such as milk, can be an important source of iodine( 18 ). It is also important to iodize all these types of salt to avoid the availability of non-iodized salt for food processing and animal consumption, which can then leak into the market for household salt.
Salt iodization standards
In 2014, WHO issued updated recommendations for the amount of iodine to add to salt( 8 ). The recommended iodine levels depend on the total amount of salt consumed as table salt and from processed foods. The guidelines assume 30 % losses of iodine from production to household but note that losses could vary widely depending on the iodization process, the quality of the salt and packaging materials, and the climatic conditions. The guidelines also assume a 92 % iodine bioavailability. Taking these assumptions into account, the amounts of iodine recommended are intended to provide the recommended nutrient intake of 150 µg iodine/d. The guidelines further note that salt iodization and salt reduction are compatible, hence they recommend addition of higher levels of iodine for lower intakes of salt and that urinary iodine concentrations should be monitored to guide adjustments of iodine concentrations in salt.
If estimated salt intake is 5 g/d or lower, as recommended to reduce the risks of non-communicable diseases( 19 ), the recommended iodine level is on average 39 mg/kg ±10 % (i.e. 35–43 mg/kg). The previous recommendation for the amount of iodine to add to salt was 20–40 mg/kg using an estimated salt intake of 10 g/d( 15 ).
As noted above, seventeen countries have passed regulations under their existing Food Act/Law. As such, standards or technical regulations for salt, such as iodine, moisture or purity levels, are specified in the existing salt iodization legislation. Eleven countries have ‘stand-alone’ legislation or regulations under an existing alternative law. Of these countries, four (Afghanistan, Bangladesh, Cambodia and Timor Leste) have included salt iodization standards in the ‘stand-alone’ law. Other countries have included iodization standards in a separate standard for salt. This has its advantages as it will likely be easier to change the salt/iodization standard than changing the original law.
Required levels for iodization at production/import level are shown in Fig. 1. It was found that while all countries have standards for iodization, not all countries specified the level at which the iodization standard should be applied – production/import, retail or household. Figure 1 also illustrates WHO recommended levels for iodization assuming salt intake from table salt and processed foods is 10 g/capita per d or 5 g/capita per d. As Fig. 1 shows, most counties in Asia have significantly higher salt iodization standards than currently recommended by WHO, particularly if salt consumption is closer to 10 g/capita per d.
Fig. 1 Required levels of iodine in salt, based on national standards (
), and WHO recommended (Rec.) iodization levels depending on salt intake (
). *Production/import level specified. Bhutan, India, Indonesia and Nepal have not specified an upper limit; for illustrative purposes, an upper limit of 20 ppm above the lower limit has been used. PNG has standards for two categories of salt: (1)=salt; (2)=table salt. China national standard shown; provinces choose provincial standards within this range (DPRK, Democratic People’s Republic of Korea; Lao PDR, Lao People’s Democratic Republic; PNG, Papua New Guinea)
Other salt standards
The legislation reviewed often also included standards for aspects of salt other than the iodine level, such as maximum levels of insoluble material, contaminants such as calcium or magnesium chloride and calcium sulfate, or heavy metals such as arsenic and mercury. Most standards also specified sodium chloride (NaCl) content and allowable moisture levels. Studies on the stability of iodine in iodized salt have indicated that iodine is lost more rapidly from salt with a high moisture content and from salt with impurities such as magnesium. Iodine retention is better in higher-quality salt( Reference Diosady, Alberti and Venkatesh Mannar 20 ).
Fortificant
The majority of legislation stipulates what iodine compound should be used for salt iodization, either in the original legislation or, more usually, in the salt standard. Most have stipulated potassium iodate but many also allow potassium iodide, sodium iodate and/or sodium iodide. Very seldom does the legislation specify who is responsible for procuring the fortificant. In practice, in many countries either a donor or the government has taken on responsibility for the cost of the fortificant, particularly at the start of the programme. The Ministry of Finance pays for potassium iodate in China, it was provided free by the Hospital of Endocrinology in Vietnam until 2005, and the Food and Drug Administration in Thailand is currently providing it for free on a temporary basis. UNICEF or other donors have provided it for free in numerous countries including Cambodia, DPRK, Lao PDR, Mongolia and Myanmar. Difficulties have been experienced in several countries in ending free or subsidized provision of potassium iodate and in a number of countries, such as Cambodia( Reference Arnaud, Mam and Oeurn 21 ) and Vietnam( Reference Codling, Quang and Phong 22 ), coverage has declined following the withdrawal of donations of potassium iodate.
Coordination and implementation stipulations
Salt iodization requirements legislated through food regulations under Food Acts/Laws indicate standards for salt, including iodization, but implementation details are not included, as routine food control systems apply. Conversely, stand-alone legislation and supporting regulations include varying detail on how salt iodization should be implemented. Implementation details include programme oversight, requirements for salt producers, enforcement responsibilities, regulation on import or transportation of salt, responsibilities for public education and penalties.
Salt iodization achievements in the region
Compared with other regions in the world, the East Asia and Pacific and South Asia regions have the highest proportion of households using iodized salt: 86 and 69 %, respectively( 5 ).
The situation in Malaysia, Vietnam and India clearly supports global evidence that mandatory legislation is more effective. Salt iodization is mandatory in only two of Malaysia’s sixteen states where IDD was thought to be endemic. A national survey in 2008 found that while 82 % of households consumed iodized salt in the areas covered by mandatory legislation, only 21 % consumed iodized salt in the rest of the country with voluntary legislation( Reference Selamat, Mohamud and Zainuddin 23 ). In Vietnam, salt iodization was mandatory until 2005, at which time 93 % of households were using adequately iodized salt. Under the subsequent period of voluntary iodization (2005–2016), however, the proportion of households using iodized salt rapidly declined to 45 % in 2010( Reference Codling, Quang and Phong 22 ). In India, a federal ban on the sale of common (non-iodized) salt existed under the Food Adulteration Act from 1998 to 2000. In 2000, however, the Food Adulteration Act was repealed and between 2000 and 2006, India had no legislation on salt iodization until the Food Standards and Safety Act of 2006 reinstated the ban on non-iodized salt. A survey in 1998/99, when non-iodized salt was banned under the Food Adulteration Act, found household use of iodized salt to be 49 %. It fell to 30 % in 2002–2004 when there was no ban and rose to 51, 71 and 78 %, respectively, in 2005/06, 2009 and 2014/15 after the Food Standards and Safety Act came into force( Reference Pandav, Yadav and Lakshmy 24 ).Footnote *
Figure 2 shows most recent data on household consumption of adequately iodized salt by country, grouped according to the type of legislation the countries have. Countries with no, draft or voluntary legislation clearly have lower coverage than those with regulations under the Food Act/Law. Relatively high coverage in Bhutan and Pakistan may be attributable to the national policy which bans the importation of non-iodized salt into Bhutan and the existence of mandatory legislation in some provinces of Pakistan. While several countries with stand-alone legislation have high coverage, particularly China, on average, coverage in countries with stand-alone legislation is lower than in those with regulations under the Food Act/Law. Information from the countries with lowest coverage in the stand-alone category indicates problems with enforcement. China and Nepal have rather unique circumstances: the Chinese salt industry was highly regulated by the government until the start of 2017, which has contributed significantly to the success of the salt iodization programme( Reference Sun, Codling and Chang 25 ). Nepal imports all of its salt and iodizes any non-iodized or inadequately iodized salt in a limited number of government-managed iodization factories at the border.
Fig. 2 Proportion of households consuming adequately iodized salt by type of salt iodization legislation. Note: Household availability of adequately iodized salt assessed by quantitative method against national standard. Exceptions are Fiji, Tuvalu and Vietnam which used semi-quantitative rapid test kits. Source of data is most recent national survey (date of survey indicated) with quantitative assessment of iodine content, except Solomon Islands which is non-national (Honiara only) and Thailand which is surveillance data. Malaysia has been included in the None/Voluntary/Draft category as it does not currently have national legislation (DPRK, Democratic People’s Republic of Korea; Lao PDR, Lao People’s Democratic Republic; PNG, Papua New Guinea)
Discussion
The current review found that most countries in the Asia and Pacific regions have mandatory salt iodization legislation. Several others are planning mandatory legislation and some have updated and strengthened existing legislation. Countries have chosen to have stand-alone laws that include extensive implementation details, or have simply incorporated the requirement for iodization into national salt regulations. Data on household coverage with adequately iodized salt in the region suggest that it is higher in countries with salt iodization regulations under the Food Act/Law. It can be argued that stand-alone legislation has the propensity to establish salt iodization as a vertical intervention, with potential constraints on implementation, while requiring fortification through food standards leads to implementation through the routine food control system( Reference Sun, Codling and Chang 25 ). Some authors have argued that regulatory monitoring systems for fortified foods are often not effective( Reference Makhumula, Dary and Guamuch 26 ) but establishing effective monitoring systems within the routine food control system is likely easier than establishing completely new and separate systems, which may occur with stand-alone legislation.
Evidence is clear that mandatory food fortification legislation is more effective than voluntary legislation( Reference Hoogendoom, Luthringer and Parvanta 11 ). Our review suggests that in Asian countries, legislating fortification through food regulations under the Food Act/Law facilitates implementation, in particular external regulatory monitoring and enforcement. It is also clear that legislation alone cannot assure a successful programme. Mandatory legislation for rice fortification has also not assured successful implementation( Reference Luthringer, Rowe and Vossenaar 27 ). Legislation is effective only if consistently and fairly enforced. For this to happen, political commitment, effective coordination systems, effective monitoring and enforcement systems, and a conducive salt industry are needed.
In Asia, legislation that bans non-iodized food-grade salt or requires all food-grade salt to be iodized is more effective than legislation which tries to legislate how all or some salt should be iodized. In particular, it is suggested that setting conditions for salt iodization hinders iodization of all salt. For example, requiring salt producers to register or have a licence can be counterproductive as such requirements provide a loophole for all those who choose not to register or do not qualify for a licence. If governments choose to try to control the industry in this way, the political commitment and enforcement capacity must exist to close all facilities not registered or licensed; there is no evidence in any of the countries reviewed that this is happening. Similarly, several Asian countries have established standards for salt that appear to be higher than the domestic salt industry can achieve, particularly in relation to NaCl and heavy metal content. Enforcement of such standards would drive many salt producers out of business and reduce the availability of domestic salt. In reality, it appears that these standards are not being enforced, which again creates a loophole for salt processors; if they are not required to meet standards for say NaCl or moisture content, why would they be expected to meet standards for iodization?
Changes in eating patterns and salt consumption highlight the importance of iodizing the salt used in food processing, in addition to table salt. Salt used in food processing may be particularly important in the East Asia region where use of salty condiments such as soya sauce, fish sauce, fermented fish, soyabean paste, etc., instead of table salt, is widespread. Limited data from Vietnam found that 35 % of total sodium intake was from seasonings, 32 % was from fish sauce and 8 % was from instant noodles, with only 6 % from table salt( Reference Codling, Quang and Phong 22 ). It is worrying therefore that some countries exclude salt for food processing, while it is ambiguous or not specified in others.
Comparison of salt iodization standards in the region with WHO recommended levels suggests that iodization standards should be lowered in several countries. It is likely that standards have been set high to compensate for losses of iodine from low-quality salt. However, WHO guidelines have assumed 30 % loss of iodine between production and consumption( 8 ). It is likely that iodine losses in the region are considerably less than assumed, especially if the salt is appropriately packaged. Countries should use median urinary iodine data to assess whether salt iodization levels are appropriate, including looking at sub-population groups consuming salt with different levels of iodine. Such data on iodine status should be used to evaluate the impact of salt iodization programmes, to ensure all population groups have adequate iodine status and none have excess.
Conclusions
In line with global data which indicate that the majority of countries have mandatory legislation for at least some types of salt( 28 ), the current review found the majority of countries in the Asia region to have mandatory salt iodization legislation. Our review highlights the importance of having legislation to achieve higher coverage at household level. Legislation under national food laws of the country appears to have facilitated higher coverage of adequately iodized salt in Asia, apparently because it has helped to establish requirements for iodization and systems of enforcement into the routine food control system. On the other hand, stand-alone legislation tends to establish salt iodization as a vertical programme and implementation modalities of some programmes in the region are hindering enforcement and sustainability. Standards for salt and salt iodization appear to be higher than the global norm or recommendations.
Adequate and appropriate salt iodization legislation can facilitate a successful intervention, but the impact will be limited if legislation is not adequately enforced. Additional facilitating factors are needed including adequate political commitment, necessary capacity and support to the salt industry, and monitoring and evaluation systems that identify constraints and problems and guide programme strengthening.
Acknowledgements
Acknowledgements: The authors would like to thank UNICEF nutrition specialists in the South Asia and East Asia and Pacific regions for contributing with documents and technical expertise to this review. Financial support: F.B., C.R. and K.C.’s time was supported by UNICEF Regional Office for East Asia and the Pacific and UNICEF Headquarters. J.P.P.-R.’s time was supported by WHO. The findings and conclusions of this article are those of the authors and do not necessarily represent the official position, decisions, policy or views of UNICEF, WHO or the IGN. Conflict of interest: K.C. serves as the regional coordinator of the IGN for Southeast Asia and the Pacific. This network is a non-profit, non-governmental organization for the sustainable elimination of iodine deficiency worldwide. The authors have no relevant interests to declare. Authorship: F.B. and K.C. conceptualized the analysis. K.C., F.B. and C.R. compiled the information and data used for this analysis and J.P.P.-R. provided critical inputs. K.C. wrote the first draft; all authors critically reviewed the content and approved the final manuscript. Ethics of human subject participation: Not applicable.
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