Address for correspondence:
Professor C Eastman
email: ceastman@med.usyd.edu.au

INTRODUCTION
According to the WHO over one billion people living within the Asia Pacific region have urinary iodine excretion concentrations less than the minimum level of 100 µg per litre and are at risk of developing one or more of the adverse effects of IDD (1). The vast geographical expanse of this region, incorporating approximately 40 countries, from tiny Pacific islands to some of the most populous nations on earth, such as India, Indonesia and China, poses a challenge in identifying and addressing the problems of IDD in this part of the world. Poverty and social disadvantage characterise many of these underdeveloped countries. IDD is most commonly, but not always, associated with lack of social and economic development, isolation and mountainous terrain. UNICEF has estimated there are more than 20 million babies born annually within the Asia Pacific region that are not protected from iodine deficiency. The majority of these babies are born in India, Bangladesh and western China

Within the Asia Pacific region, IDD has been recognised as a serious public health problem in India, Bangladesh, Indonesia, Myanmar (Burma), Cambodia, Thailand, China (western provinces including Tibet), Mongolia, North Korea (DPRK) Laos, Malaysia, Papua New Guinea, East Timor and the Philippines. This is not an exclusive list. In some of these countries serious iodine deficiency is limited to remotely located pockets of the population that are difficult to reach with iodised salt on a sustainable basis. Despite all the difficulties, there has been considerable improvement in household iodised salt coverage in most of these countries over the past decade, giving hope to the realisation of the goal of sustainable IDD control within the next decade (Figure 1).

In the South Pacific there have been sporadic reports of goitre being endemic in parts of Vanuatu, New Caledonia, Fiji, Samoa and some of the other smaller islands such as Tuvalu. Because many of the smaller countries in the Asia Pacific region are island states, with large expanses of coastline and presumed easy access to seafood, it has erroneously been assumed that iodine deficiency is not a significant endemic problem in the Pacific. As a consequence, little or no data on IDD has been collected in many of the poorer, smaller nations and a disregard for the crucial role of iodine nutrition has characterised the position of some of the more affluent nations such as Australia and New Zealand (2).

Examples of successful IDD elimination programs
China, Vietnam, Thailand and Indonesia are good examples of countries that have invested enormous effort and resources in IDD elimination programs and are now reaping the social and health benefits of these investments (3). For these reasons we will look at the recent history and achievements of two of these countries, China and Vietnam, with which we have had first-hand experience in combating IDD. Both China and Vietnam have met the overall target of achieving iodised salt coverage in excess of 90% of all households.(Figure 1)

Peoples Republic of China
Goitre has been recognised as a problem in China for thousands of years. Although the role of iodine was unknown until the 19^th century, seaweed and burnt sea-sponge were advocated for the treatment of goitre in China over 4000 years ago. However, it was not until the 1960s that endemic goitre was acknowledged as a nationwide, public health issue. The connection between iodine deficiency and brain damage, that is far more common and subtler in its manifestations than classical cretinism, was first recognised by Chinese scientists (Drs Ma Tai and Lu TZ) three to four decades ago. They called this condition “subclinical cretinism” and drew attention to the fact that severe iodine deficiency could affect whole communities, adversely impacting on the intellectual, physical, economic and social development of the people (4). Over the next two decades numerous surveys conducted in many regions of China revealed that goitre was widespread throughout the country and cretinism and subclinical cretinism were common in severely iodine deficient areas. Before any iodised salt prophylaxis programs were commenced endemic goitre was estimated to be present in 20% to 30% of the population in the majority of provinces, thus affecting millions and millions of people. It is a matter of speculation as to how many tens of millions of the population suffered from some form of brain damage due to iodine deficiency. There are stories of places being labelled “idiot villages” because overt cretinism was common and most of the population suffered from goitre and mental disability (4). The recognition of defective cognitive performance, coupled with impaired child development, elevated the concern about iodine deficiency from an endocrine problem of thyroid dysfunction resulting in goitre to that of a reduction in human resources and constrained economic development (5). A recent meta-analysis undertaken on observational studies in China confirmed an average IQ loss of approximately 12 points in children born in moderate to severe iodine deficient areas and that this loss can be prevented by appropriate iodised salt intervention programs (6). The findings of reduced cognitive performance and lower intelligence in many segments of the population in China, and not the high prevalence of endemic goitre, has provided the impetus for the serious national commitment and effort to eliminate IDD from the country. The story of how this has been achieved is quite remarkable and an inspirational triumph in public health achievements in modern times (4,5).

At the historic UN Summit for Children held in 1990, China was a signatory to the declaration of the goal of virtual elimination of IDD by the year 2000. With the assistance of international agencies and bilateral aid donors from Australia and Canada, the State Council hosted a high-level advocacy meeting in 1993 involving governors of all provinces, and representatives of government, the salt industry, health care institutions, together with civic leaders and international experts to develop a commitment and plan for the elimination of IDD in China. The State Council approved regulations for mandatory iodisation of all edible salt (Universal Salt Iodisation or USI) and appointed a multi-sectoral leadership and management group to oversee the effort and to provide support for training of personnel and education of the population. A national monitoring program was put in place to support the implementation of this initiative. When the first national survey was performed in 1995 the population coverage of iodised salt was approximately 30% and rose to over 90% by year 2000 to achieve the target for USI. Iodine concentrations in edible salt have been adjusted to prevent excessive intake (4).

IDD in Tibet
While the national targets of household coverage of iodised salt and a goitre rate of less than 5% in schoolchildren have been achieved, there remain some serious problems in several provinces in the remote western region of China. In particular, Tibet continues to suffer from serious iodine deficiency. Goitre rates have been as high as 50%, cretin rates in some villages up to 13% and the average IQ of children being only 85 (7). In 1999 with support from WHO, AusAID, and UNICEF, we undertook a feasibility study for the development of a whole of Tibet IDD elimination program. The project comprised support for the development of an iodised salt industry, development of health education and communication materials, training, capacity building, management support and implementation of an interim iodised oil supplementation program for infants and all women of childbearing age. AusAID contributed over $2 million and WHO provided umbrella support. This program has been successful in reaching over 90% of the target population with the iodised oil supplements. It is estimated that over 170,000 newborn babies have had their brains protected from iodine deficiency through this program (8). We are in the process of transferring all responsibilities to the Tibet government and the Tibet Department of Health who are committed to providing iodised salt to all of their citizens.

Vietnam
The first IDD control programs in Vietnam were established in the early 1970s. The initial focus was on the mountainous provinces in North Vietnam where goitre rates were as high as 55 %. A nationwide survey was undertaken in 1993 and the average goitre rate in children was found to be 22 % and the median urinary iodine excretion was only 32 ug/l. The government of Vietnam responded by establishing a National IDD Control Committee and developed a nationwide network of salt iodisation plants. Australian development aid, through AusAID and Westmead Hospital, provided technical and other assistance in establishing this program. In 1999 the government issued a decree relating to the production and supply of iodised salt for human consumption. Currently, the rate of coverage for adequately iodised salt in Vietnam has risen to over 90%. The Vietnamese government has a policy for subsidising iodised salt for some 12 million ethnic minorities in mountainous areas of the country. There is a very well organised and efficient national IDD committee that oversees monitoring of the IDD elimination program. Provincial IDD committees undertake monitoring surveys three times a year and there is a national survey every second year. There is a central laboratory in the Hospital for Endocrinology in Hanoi that oversees all laboratories monitoring for urinary and salt iodine levels. Information Education and Communication (IEC) activities are well developed. Recently the government strengthened legislation to eliminate non-iodised salt from the marketplace. Vietnam has achieved the USI goal of over 90 % coverage of the population and reduction of goitre rates to less than 10 % (Figure 1)

What are the lessons we have learned in these developing countries?

• Framing the message of iodine deficiency around brain damage, loss of IQ and impaired mental and physical development is far more powerful and persuasive than advocating iodine prophylaxis programs for endemic goitre
• Advocacy at government level is essential to influence those that have the power to make decisions. IDD is a “whole of government” issue affecting social and economic development and not simply a public health problem. Obtaining and maintaining high-level political commitment to eliminating IDD is essential.
• Acceptance at a national level that USI (mandatory fortification of all edible salt with iodine) is the most appropriate vehicle for normalising iodine nutrition within a community and that acceptance of USI must be followed by implementation of legislation and regulations underpinning this initiative.
• Multi-sectoral involvement is a prerequisite for success. The salt industry is as an important player as the health sector in achieving USI and must accept responsibility to ensure supply of iodised salt.
• Education of the public is necessary to create demand for iodised salt and sustainability of optimal iodine intake.
• A vital component of successful outcome is the implementation of a program for regular monitoring of the population iodine intake and the quality assurance of iodised salt at production and retail level with mandatory public reporting of the data.
• Where iodised salt cannot be provided to all citizens, and in particular children and women of childbearing age, an iodised oil supplementation program is an effective means of protecting the brains of the newborn and the growth and development of infants and children and should be employed as an interim strategy.

Re-emergence of Iodine Deficiency in Australia and New Zealand
Mild iodine deficiency has re-emerged in Australia and New Zealand over the past decade and poses a significant health risk to future generations of these countries (9,10). Median urinary iodine excretion (UIE) levels in Australia have decreased from over 200 ug/l in 1990 to less than 100 ug/l by 1999 (9). Iodine deficiency has resurfaced after more than half a century of iodine sufficiency because of changes in work practices in the dairy industry and because consumers do not purchase iodised salt and the food industry does not use iodised salt in food preparation. The dramatic decline in iodine intake in the Australian population has been attributed to the major decrease in iodine concentrations in dairy milk (2,11). Since the early 1960s the major source of iodine in the Australian diet has been from iodine contamination of milk by iodophores used as sanitising agents in the dairy industry. These chemicals have been replaced by chlorine-based disinfectants. Because Australia has not had an ongoing iodine nutrition monitoring program (except for the island state of Tasmania), the problem of iodine deficiency has only come to light through the efforts of researchers interested in IDD (2). Health authorities have shown little or no interest in addressing the problem because mild iodine deficiency has not seen as a threat to human health.

Sales of iodised table salt represent less than 20 % of the edible salt market sales in Australia. There is no legislation mandating the use of iodised salt in the food industry and there is little awareness among the public of the problems of IDD. The situation in New Zealand is very similar to that in Australia. Both countries share a common food standards authority (Food Standards of Australia and New Zealand FSANZ) so any changes to legislation regarding mandatory salt iodisation will need to be agreed between them before we can expect change.

A National Iodine Nutrition Study has recently been completed in Australia to obtain a snapshot of urinary iodine levels and thyroid size in 8 to 10 year old schoolchildren. The median urinary iodine level is under 100 ug/l, and there is increased size of thyroid glands by ultrasound measurement, consistent with mild iodine deficiency (11). Similar results have been obtained in studies of New Zealand children.

Conclusions
The goal of achieving USI, and virtual elimination of IDD, within the Asia Pacific region by end of 2010 remains a formidable challenge, and is most likely not achievable. Unless IDD elimination efforts can be reinvigorated in a number of countries, where there has been little or no progress in recent years, the goal is not attainable in the foreseeable future. The commitment and achievements in countries such as China, and more recently Vietnam, provide inspiration to others that sustainable IDD elimination can be realised throughout the Asia Pacific region.

More information is needed from properly constructed surveys within the smaller island states of the Pacific to define the extent and severity of iodine deficiency in these countries. Government intervention banning the importation of all non-iodised edible salt would provide an immediate solution to the problem. Within the more affluent countries such as Australia and New Zealand education of the public is needed to create a demand for iodised salt and to lobby governments for implementation of mandatory salt iodisation. In the interim there is a good case to be made for all pregnant and breastfeeding women in these countries to be taking daily iodine supplements to ensure optimal iodine nutrition during critical times of human development.