Universal Salt Iodisation: Lessons learned from Cambodia for ensuring programme sustainability

Abstract Iodine deficiency is the leading cause of preventable intellectual disability in the world, but it has been successfully prevented in most countries through universal salt iodization (USI). In 2011, Cambodia appeared to be an example of this success story, but today, Cambodian women and children are once again iodine deficient. In 2011, Cambodia demonstrated high‐household coverage of adequately iodized salt and had achieved virtual elimination of iodine deficiency in school‐age children. However, this achievement was not sustained because the USI programme was dependent on external funding, and the national government and salt industries had not institutionalized their implementation responsibilities. Recent programmatic efforts, in particular the establishment of a regulatory monitoring and enforcement system, are turning the situation around. Although Cambodia has not yet fully regained the achievements of 2011 (only 55% of tested salt was adequately iodized in 2017 compared with 67% in 2011), the recent steps taken by the government and the salt industry point to greater sustainability of the USI programme and the long‐term prevention of iodine deficiency in children, women, and the general population.


| INTRODUCTION
There has been widespread adoption of mandatory universal salt iodization, the iodization of all salt for human consumption, including salt for food processing, throughout the world since the 1990s, and it is one of the most successful public health programmes in the past 30 years (WHO, 2014). A new global database on food fortification programmes indicates that 108 countries currently have mandatory legislation for salt iodization (Global Fortification Data Exchange, 2018). Today, 86% of households worldwide use iodized salt (UNICEF, 2017), and as a result, out of 139 countries with data on population iodine status from the past 15 years, only 19 countries report insufficient iodine intake (Iodine Global Network, 2017). This compares with 110 countries estimated to have insufficient iodine intake in 1993 (WHO, 1999). Although Cambodia is one of the 108 countries with mandatory salt iodization legislation, most recent data from Cambodia indicates that it is one of the small number of countries remaining in the world with insufficient iodine intake.

| UNIVERSAL SALT IODIZATION AND PREVENTION OF IODINE DEFICIENCY IN CAMBODIA
Cambodia, like many other countries around the world, started to implement a salt iodization programme after WHO and UNICEF recommended universal salt iodization as the main strategy to achieve elimination of iodine deficiency disorders in 1993 (UNICEF/WHO Joint Committee on Health Policy, 1994). In 1996, the Royal Government of Cambodia established the National Sub-Committee for Control of Iodine Deficiency Disorders, with the commitment to achieve iodization of all salt for human and animal consumption, including salt for food processing . In 1997, a national survey reported an average national goitre prevalence in primary school children of 12%, indicating mild deficiency, but moderate deficiency and severe deficiency were found in nine and four of the 20 provinces sampled, respectively (Conkle, Carton, Un, & Berdaga, 2013 Kampot and Kep (SPCKK), establishing a system to coordinate the processing, marketing, and sale of salt, including its iodization. As the majority of Cambodia's salt is domestically produced in Kampot and Kep provinces, the SPCKK is currently the sole domestic supplier of raw salt, and the creation of the SPCKK was a key factor in the subsequent success of the salt iodization programme.
Following the issuance of mandatory salt iodization legislation and the creation of the SPCKK, production of iodized salt increased rapidly, and on average, 82% of households were recorded as having iodized salt between 2005 and 2011 ( Figure 1). Although this achievement was noteworthy, the potassium iodate used to fortify the salt throughout this period was paid for with external funding from UNICEF. In 2010, UNICEF ended its support of the potassium iodate, and the SPCKK committed to maintain iodization and purchase sufficient potassium iodate. Little information was generated by the programme after 2011 until UNICEF collaborated with the Ministry of Planning to undertake a market survey to assess iodization compliance in 2014. The survey collected 1,862 samples of salt from major rural and urban markets in all 24 of Cambodia's provinces and recorded that only 38% of samples contained any iodine (Laillou, Mam, Oeurn, & Chea, 2015). Although not representative of national availability of iodized salt, the market survey was the first confirmation that the once successful salt iodization programme had declined. Figure 1 shows the rise and fall in the proportion of households using iodized salt (i.e., salt with any amount of iodine; not necessarily adequately iodized).

Key messages
• Iodine deficiency has the potential to significantly constrain national social and economic development, through the impairment of early child development.
However, it has been successfully prevented in most countries through universal salt iodization.
• In Cambodia, external funding contributed to significant achievements in universal salt iodization and elimination of iodine deficiency; however, in the long term, it compromised programme sustainability.
• Experience in Cambodia and elsewhere shows that establishing and ensuring appropriate and effective regulatory monitoring and enforcement of mandatory salt iodization legislation is essential. Without government enforcement, programme sustainability is jeopardized, and the commitment of the private sector is at stake.  Table 1). The reason for the continued poor iodine status, despite an apparent rise in the proportion of salt that is iodized, may lie in the level of iodization. Although the 2016 and 2017 Market Surveys found 71% and 84% of tested salt samples to be iodized, only    (Table 1).
Data on the iodine status, based on MUIC values, of school-age children, children 6-59 months, women of reproductive age, and pregnant women are shown in Table 1  This may reflect the fact that after 6 months of age, infants are reliant on dietary iodine intakes rather than iodine stores provided by maternal iodine and breastmilk (Delange, 2004).   Costs of fortification can only be spread across the total national food supply in the context of mandatory fortification that is enforced however, as enforcement creates an even playing field for all producers.
Hence, the best way governments and development agencies can support industries to implement universal fortification is to create a safe and fair environment for fortification through consistent and effective enforcement. Support in the form of free fortificant or donations of equipment may appear to be helpful but simply delays genuine and include external regulatory monitoring data on compliance and production practices at salt and processed food production facilities and points of import, quantitative assessment of iodine content of household salt, and assessment of iodine status of priority target groups with subnational stratification. Such data should be jointly reviewed by programme stakeholders to identify programme weaknesses and make adjustments to programme design and implementation, such as to fine-tune standards for iodization, adjust regulatory monitoring requirements or practices, and to identify communities that are not able to access adequately iodized salt, in order to trace back the causes (e.g., inadequately iodized salt from a single importer or producer) and address them.

| CONCLUSION
Salt iodization has proven a highly effective intervention globally to improve iodine nutrition in the general population (Aburto, Abudou, Candeias, & Wu, 2014). It is intended as a long-term, sustainable strategy and is becoming the industry norm as more and more countries adopt mandatory fortification (Global Fortification Data Exchange, 2018). Iodine deficiency has returned to Cambodia because previous salt iodization implementation was reliant on external funding and is jeopardizing national economic and social development by compromising early child development. Cambodia's experiences are a demonstration that financial contributions of development partners for fortification need to be used strategically to facilitate and institutionalize fortification practices, such as through external monitoring, but not to directly fund them, in order not to jeopardize sustainability and industry and government ownership. Current actions in Cambodia to establish regulatory monitoring systems appear to be working to create a supportive environment for industry to take on their responsibilities in salt iodization with concurrent improvements in availability of iodized salt and hopefully also improvements in iodine status. As key programme actions are no longer reliant on external support, it can be anticipated the programme achievements will be sustained.